;\

Jl

THE LIBRARY

OF

THE UNIVERSITY
OF CALIFORNIA

PRESENTED BY

PROF. CHARLES A. KOFOID AND
MRS. PRUDENCE W. KOFOID

THE NEW SYDENHAM SOCIETY.

INSTITUTED MDCCCLVIIL

VOLUME CXXXII.

MICRO-ORGANISMS

WITH SPECIAL REFERENCE TO THE

ETIOLOGY OF THE INFECTIVE DISEASES,

DR. C. FLUGGE,

O. 0. Professor and Director rf the Hygienic Institute at Gottingen.

Translated from the

SECOND AND THOROUGHLY REVISED EDITION OF " FERMENTE
UND MIKROPARASITEN."

BY

W. WATSON CHEYNE, M.B.,

SURGEON TO KING'S COLLEGE HOSPITAL.

WITH 1 -i -i 3D K, .A. W I IT G S.

THE NEW SYDENHAM SOCIETY.
MDCCCXC.

K-QRH

©o flic

O

J.

M358416

PEEFACE.

THE first edition of the present work formed a part of the
Handbuch der Hygiene, edited by von Ziemssen and von
Pettenkofer ; the description, however, there given was incom-
plete, because it was intended to supplement it by articles by
other authors on " Air," " Soil," and " Common Diseases." As,
however, the appearance of these supplementary articles has been
greatly delayed, and as also, on account of the great divergence
of the views on the subject of micro-organisms, uniformity of
description was scarcely possible, I have preferred to publish the
second edition of " Micro-organisms " in a separate form, and to
add chapters on the subjects which were not treated of in the first
edition.

Apart from these additions, the chapters of the previous edition
have been fully revised and in great part re- written.

There are two leading ideas which have guided me in the pre-
paration of the present edition. In the first place, I desired to
give a practically useful classification of bacteria. For this pur-
pose I have described as fully as possible the culture characteristics
of the individual forms, and have provided a key for the diagnostic
separation of the different species of bacteria in each of the three
chief groups.

I have not made any attempt to give a scientific classification
of the bacteria, and the characteristics described are only of use
practically in enabling the reader to obtain a general idea as regards
the species already known, and to recognise new species should
he meet with them, &c. In this way material will be collected,
which may, perhaps, at a future period be of use in leading us to
a truly scientific classification.

VI PREFACE.

Our knowledge of micro-organisms is as yet so imperfect that
for the present we absolutely require some such rough method of
making ourselves mutually intelligible. The attempts to classify
bacteria according to other principles, and with reference to their
ontogenetic and phylogenetic development are doubtless justified,
but in view of the small number of definite observations are
premature, and at any rate for practical purposes are in the mean-
time completely useless.

Xor can we form a practical classification on the basis of spore
formation, because in the case of most species it is very difficult
to decide whether, under what conditions, and how they fructify.

On the other hand, by careful attention to the characteristics
of growth on certain soils, it is comparatively easy, as the
experience of several years has taught us, for the beginner to
find his way in the labyrinth of the forms of bacteria, and we are
certainly justified in the meantime in joyfully trusting ourselves
to this Ariadne thread, always bearing in mind that the indica-
tions so obtained are provisional and only pave the way for more
thorough knowledge.

For the diagnostic summary attempted here it was necessary
to give names as far as possible to the individual species of
bacteria. The culture characteristics have for the most part
formed the bases for these names, and hence they have, like the
classification itself, only a provisional importance, and are only
justified in so far as they render mutual understanding easier for
the present. Should some authors be dissatisfied with the names
which have here been chosen for the bacteria first described by
them, they may excuse my action when they remember the
necessity for a terminology, the provisional character of the
names, and the possibility of altering them at any time.

Some of the more common forms of saprophytes collected in
this Hygienic Institute are only described incompletely, and with
almost exclusive reference to the characters which are of use in
differentiating them. A more complete study of these forms is
proposed at a later time. I am deeply indebted to the workers
at the Institute, Drs. Oberdiek, Henrijean, Guarncri, Kreibohm,

PREFACE. Vll

&c., but in particular to my assistants, Dr. Deneke and Dr.
Praussnitz, for the help which they have given me in this
arduous work.

The second idea which guided me in altering the former
edition has reference to the etiology of the infective diseases.

As to the mode of spread of these diseases we have as yet
received explanations almost entirely from the experiences of
medical practice, and from statistical observations. The
number of definite results obtained in this way has, however,
been extremely small, and where a law such as the peculiar local
and seasonal distribution of typhoid and cholera epidemics is
recognised we are, with regard to the significance and expla-
nation of the phenomena, thrown back on a series of more or less
probable hypotheses.

The bacteriological investigations of the last few years have
produced a complete change in this respect. By the discovery
of numerous disease germs, and of the methods of their pure
cultivation, it has become possible to study experimentally the
conditions of life of the infective organisms, their mode of life,
their relation to their surrounding, their transportability, and the
mode of their entrance into man, and thus to obtain information
as to the causes of the peculiar mode of spread of epidemic dis-
eases, in a manner incomparably quicker and more trustworthy
than by empirical and statistical methods.

I have as far as possible in the present work made use of
these advances of the most recent scientific investigations, the
bearing of which is decidedly underrated, and have attempted
to explain the mode of spread of infective diseases, more espe-
cially of cholera, by reference to the facts ascertained by experi-
ment as to the characteristics of the causal agents.

It must be evident that we have already gained in this
way, in the case of a number of infective diseases, a deeper
insight into their mode of spread and the prophylactic measures
necessary in combating them. In the case of many diseases we
do not as yet fully understand their mode of spread ; nevertheless
by the aid of the results of bacteriological investigations we can

Ylll PREFACE.

at least understand what are the points which will eventually
lead to the elucidation of the peculiarities in this respect ;
and we can recognise most clearly that it is not correct to
regard in a one-sided manner the soil or the water as the only
important factor. In every case we may hope that a continued
experimental investigation carried on with a definite aim will
lead us most quickly to an increase of our knowledge, and to a
rational method of prophylaxis against the epidemic diseases.

Many other duties have prevented me from finishing the
publication of this hook as quickly as I could have wished. I
have not heen able to utilise completely the literature of 1885,
and only the most important of the works which have appeared
in the present year have been added while the book was passing
through the press. The yearly report of micro-organisms lately
published by Baumgarten, and written with as much care as
knowledge, relieves me, however, of the necessity of giving in an
appendix a notice of the more recent works.

C. FLUGGE.

GdlTINGEX,

August 24th, 1886.

LITERATURE,

TEXT-BOOKS, HAND-BOOKS, REVIEWS, &c.

KHRENBERG, die Infusionsthierchen als vollkommene Organismeu.

Leipzig, 1838.

DU.IARDIN, Histoire naturelle des zoophytes. Paris, 1841.
HKNLE, Pathologisclie Untersuchungen, 1840. Handbuch dor

rationellen Patliologie, 2 Band. 2 Abth., 1853.
BONORDEN, Handbuch der allgemeinen Mykologie, 1851.
BAIL, Die wichtigsten Satze der neueren Mykologie. Jena, 1 361 .
HALLIER, Die pflanzlichen Parasiten. Leipzig, 1836. Parasito-

logische Untersuchungen. Leipzig, 1868. Phytopathologie, ib.

1868.
DE BARY, Morphologic und Physiologic der Pilze &c. 2 Br1. 1

Abth. von Hofmeister's Handbuch der physiologischen Botanik.

Leipzig, 1866.
EIDAM, Der gegemviirtige Standpunkt der Mykologie, 2 Ann.

Berlin, 1872.

SACHS, Lehrbuch tier Botanik, 4 Aufl. Leipzig, 1874.
PFEFFER, Pflanzenphysiologie, ein Handbuch, &c., 2 Bde. Leipzig.

1881.
LEUNIS, Synopsis der Pnanzenkunde ; 3 Abth., Kryptogameu,

bearb. von Frank. Hannover, 1877. 3 Aufl, 1883 (in the

press).
RABENHORST'S Kryptogamenfloi-a, 1 Bd. Pilze, von Winter.

Leipzig, 1881.

ROBIN, Histoires des vegetaux parasites.
VAN TIEGHEM, Traite de botaniquc, 1883.
GROVE, A Synopsis of the bacteria and yeast-fungi and allied

species.

MAGNIN, Les bacteries. Paris, 1878.
References by Richter and Birch-Hirschfeld in Schmidt's Jalir-

biichern der ges. Medicin especially, Bd. 159, S. 169 ; 1875, Bd.

166, S. 169; Bd. 163, S. 57.

LEX, in Roth und Lex, Militargesundheitspflege, I., S. 167, and 48.0.
ZIEGLER, LehrK der patholog. Anatomic, 3 Aafl. Jena, 1885.

1

•2 LITERATURE.

KLEHS, Beitrage zur Anatomic der Schusswunden. Leipzig, 187*2
—1873. — Article " Ansteckende Krankheiten " in Eulenburg's
Realency lopadie .

DUCLAUX, Ferments et Maladies. Paris, 1882.

PERRONCITO, Parassiti dell* uomo e degli animali iitili : delle qui
comuni malatti da essi prodotte : profilasi e cnra relativa. Milano,
1882.

ROCIIAS, Les schizophytes parasites de 1'homme. Bale, Lyon,
Geneve, 1884.

FOL, Les microbes. Geneve, 1885.

WOODHEAD and Hare, Pathological Mycology, 1 Section. Edin-
burgh, 1885.

CORNIL et Babes, Les Bacteries. Paris, 1885.

ZOPF, Die Spalt-pilze, 3 Aufl. Breslau, 1885.

DE BARY, Vergleichende Morphologic, u. Biologic der Pilze. Myce-
to/oen n. Bacterieii. Leipzig, 1884.

FISCH, Die systematische Stellung der Bakterien. Biolog. Centralbl.,
Bd. 5, 1885.

TOMMASI-CRUPELI, Instituzioni di Anatomia patologica. Torino,
1884.

($ee also under u Production of Disease"}

GENERAL LITERATURE.

COHN, TJntersuch. iiber d. Entwickelungsgesch, d. microscop. Algen
u. Pilze, Nov. Act. Leop., Vol. 24, 1853.
— , Beitrage zur Biologie der Pflanzcn, I. Band 1875 ; II. Band

1877 ; III. Band 1879-1880.
DE BARY u. WORONIN, Beitrage z. Morpliol. u. Physiologic der

Pilze. Frankfurt-a-M. 1864, 1866, 1870.
HOFFMANN, Mykologische Berichte. Giessen, 1870 — 1872.
NXGKLI, Beitrage z. wissenschaftlichen Botanik, Heft. II. (1860).
— , Die niederen Pilze in ihren Beziehnngeii zu den Infections-
krankheiten. Miinchen, 1877.

— , Unteimtehungen iiber niedere Pilze. Miinchen, 1882.
REINKB u. BERTHOLD Die Zersetzung der KavtofFel durch Pilze.

Berlin, 1879.

ClENKOWBKl, Zut- Morphologic der Bakterien. Petersburg, 1876.
ZOPF, Zur Morphologic der Spaltpflanzen. Leipzig, 1882.
— , Zur Kem-fcniss des Phykomyceten I. Halle, 1884.
— , Zur Morphologic u. Biologie der niederen Pilzthiere (Mona-
dinen). Leipzig, 1885.

LITERATURE. O

ZOPF, Die Pilzthiere oder Schleimpilze. Breslau, 1885.
DAVAINE, Recherches sur les Vibrioniens. Compt. "rend., 1884,
. T. 59, p. 629.

PASTEUR, Animalcules infusoires, -&c. Compt. rend., LII., 1861.
JOUBERT ET CHAMBERLAND, La thoorie des germes et ses applications

a la medicine et chirurgie. Compt. rend. 1878, Vol. 86, p. 1037

-1043.

KLEBS, Beitrage zur Anatomic der Sehusswtmden. Leipzig, 1872.
BiLLROTH, Untersuchnngen iiber die Vegetationsformen d. Cocco-

bacteria septica. Berlin, 1874.

LIONEL BEALE, Disease germs, their nature and origin, 1872.
KLEIN, Experimental Contribution to the Etiology of Infections

Diseases, with special reference to the Doctrine of Contagium

vivum. Proceed, of the Roy. Soc. of London, Febr., 1878, Vol. 27.
AUPRECHT, Pathologisehe Mitthoilungen., I. Heft. Magdeburg,

1881, bei Faber.
BAUMGARTEN, Ueber pathogene pfllanzliche Organismen, II. Die

pathogenen Sehizomyceten. Berlin, 1884.
MITTHEILUNGEN des kaiserlichen Gresundheitsamts, Bd. I., 1881,

Bd. II., 1884.
AHBBITEX aus dem kaiserl. Gesumlheitsamt., Bd. I., 1885.

«t

SPONTANEOUS GENERATION.

. . (See also " Fermentation''')

SOHULZK, Gilbert's Annalen der Physik u. Chemie, 1838, Bd. 33,

S. 487.
PJ.HRENHF.II. r, Abhdl. der Konigl. Akad. d. Wissench. zu Berlin,

Jahrg. 1830, 1832, 1834-1835. Uebersicht der seit, 1847,

fortgesetzten Untersuchungen iiber das von der Atmosphare

unsichtbav getragene reiche organische Leben. Aus den Abhdl.

d. Kgl. Akad. d.Vissensch. z. Berlin, 1871, C, Vogfc.
SCHWANX, Gilbert's Annalen der Chemie u. Physik, 1837, Bd. 41,

S. 184.
SCHRODER u. v. Dusc n, Annalen der Chemie u. Pharm., 1854, Bd.

89, S. 232-243; 1859, Bd. 109, S. 35—52; 1861, Bd. 117, 8.

273—294.

F. SCHULZE, Ami. d. Phys. u. Chem., 1836, Bd. 39.
POUCHET, Heterogenie ou traite de la generation spontanee. Paris,

1859.

POUCHET ET HOUZEAU, Compt. rend, de 1'Acad. des sc., 1858, Bd. 47.
PASTEUR, Compt. rend, de 1'Acad. des sc., 1860, Bd. 50 u. 51.
HUIZINGA, Arch. f. d. ges. Physiologic, 1873, 1874, 1875.

4; LITERATURE.

BASTIAN, Centralbl. f. d. med. Wissenschaften, 1876, S. 521.
— , Compt. rend., Bd. 83, No. 8.
— , On Fermentation and the appearance of Bacilli, Micrococci,

and Torulae in Boiled Fluids. London, 1877.
CHETNE, Antiseptic Surgery, 1882.

ascHEiDLEN U. PuTZEYS, Pfliiger's Arch., 1874, Bd. 9, S. 163—174.
SAMUELSON, Pfliiger's Arch., Bd. 8, S. 277, 288
BURDON-SANDERSON, Nature, Bd. 8, S. 478.
NuESCH,Die Nekrobiose inmorphologischerBeziehung. Schafhausen,

1875.

ARNDT, Untersuchungen iiber die Entstehung von Coccen u.
. Bacterien in organischen Substanzen. Virch. Arch., 1880, Bd.

82, S. 119—146.
TASCHENBERG, Lehre von der Urzengung sonst uiid jetzt. Halle,

1883.
BE"CHAMP, Les Microzymes dans leurs rapports avec I'heterogenie,

<fcc. Paris, 1883.
WIGAND, Entstehung und Fermeiitwirkung der Bacterien. Marburg,

1884.

On the Existence of Germs ini Living Tissues.

VAN DEN BROCK, Ann. f. Chemie u. Pharm., 1860, S. 115, 175.
PASTEUR, Compt, rend., 56, S. 738, 1194, 1863, Bull, de 1'acad. de

med., 1875. Etudes sur la biere, 1876, p. 46.
GAYON, Recherches sur les alterations spontanees des ceufs. Paris,

1875, p. 45.

• — -, Compt. rend., 1873, Jan.
LfiDERS, Arch. f. mikr. Anat., 8,. S. 317, 1867.
SAMUEL, Arch. f. exp. PathoL, 1873, Bd. 1.

STERNBERG, John Hopkin's Univ. stud. biol. Baltimore, Vol. 2.
LEWIS, Quart. Journ. of Microsp. sc., 1879, Vol. 19.
HENSEN, Ibid., p. 342. . .
RINDFLEISCH, Virch. Arch., 54, S. 39, 1872,
CHAUVEAU, Compt. rend., 76, p. 1092, 1873.
PASCHUTIN, Virch. Arch., 59, S. 490, 1874.
KOLACZEK, Centralbl. f. Chirurgie, 1875, S. 197.
TIEGEL, Virch. Arch., 60, S. 453, 1874.
KOUKOL-YASNOPOLSKI, Pfliiger's Arch., 12, S. 80. 1876.
SERVEL, Compt. rend., 79, p. 1270, 1874.
BURDON- SANDERSON, Thirteenth report of the Medical Oflice of tho

Priv. Counc., p. 63 ; Quarterly Journ. of Microscop. sc., 1871 ;

The British Medical Journ., 1878, p. 119.
NRSCKI u. GIACOSA, Journ. fiir pract. Chemie., N. F., Bd. 19 u. 20.

LITERATURE. i>

ROBERTS, Philosophical Transactions, 1874, p. 457.

CAZENEUVE ET LIVON, Compt. rend., 45, p. 571, 1877.

BILLROTH, Arch. f. klin. Chir., 20, S. 432, 1877. Coccobacterift

septica, p. 59 ff.

WEISSGERBER u. PERLS, Arch. f. exp. Pathol., Bd. 6.
LISTER, Journ. of Microsp. sc., 1878, p. 179.
WATSON CHEYNE, Path. Soc. Transactions, 1879, and Antiseptic

Surgery, 1882.
CHIENE AND COSSAR EWART, Journ. of Anat. and Phys., 1878, April.

p. 448.
KOSENBACH, Ueber einige fundamental Fragen in der Lehre yon

den chirurgischen Infectionskrankeiten ; Deutsche Zeitschr. f.

Chirurgie, Bd. 13, S. 334, 1880. There also detailed reference

to Meissner's experiments.
ZAUN, Virchow's Archiv, Bd. 95.
LEUBE, Zeitschr. f. klin. Med., 1881, Bd. 3.
FIRKET, Annal. de la soc. med. chir. de Liege, 1879, Vol. 18.
HORSLEY AND MOTT, Journ. of Physiolog., 1880, Vol. 3.
HAUSEK, Arch. f. ges. Physiol., Bd. 33.
v. HOFFMANN, Untersuchungen iiber Spaltpilze im menchslichen

Blute. Berlin, 1884.
MARCHAND, Sitzungsber. d. Ges. zur Beforderung d. ges. Naturwis-

senchaften zu Marburg 1885, Marz.

GENERAL LITERATURE ON MOULD FUNGI.

LEUNIS, RABENHORST, DE BARY, p. 1.

BREFELD, Botan. Untersuchungen iiber Schimmelpilze, I. — IV.

SIKBENMANN, Die Fadenpilze. Wiesbaden, 1883.

VAN TIEGHEM, Sur le developpement de quelques Ascomycetes

(Aspergillus). Bull. soc. bot. de France, 1877.
— , Recherches sur les Mucorinees. Ann. sc. nat., 1873, 1875, 1878.
ZIMMERMANN, Das Genus Mucor. Chemnitz, 1871.
BREFELD, Landw. Jahrb. V. 1876 (Mucor racemosus).
For further facts see Leunis und de Bary.

DISEASES OF PLANTS DUE TO MOULD FUNGI.

TULASNE, Memoire sur les Ustilagin. compar. aux Uredin. Annal.
des sc. natur., 3 ser., T. 7, 1847; T. 2, 1854. Mem. sur
1'Ergot. Ibid., T. 20.

DE BARY, Untersuchungen iiber die Brandpilze, 1853. Untersuch-
ungen iiber Uredineen. Monatsber. d. Konigl. Acad. d. Wiss. zu
. Berlin, 1864r— 66.
— , Annal. de Landwirthschaft., 23 Jahrg., 1865.

6 LITERATI; EK.

DE BARY, Recherches sur le developpement do quelques champig-
nons parasites. Ann. des. sc. nat. 4 ser. II., 1865.

r»E BART u. WORONIN, Beitrage zur Morph. u. Phys. der Pilze. III.
Frankfurt, 1870.

KUHN, Die Kranklieiten der Culturgewachse. Berlin, 1858.

WILLKOMM, Die mikroskopischen Feinde des Waldes. Dresden.
1866.

HOFFMANN, Botanische Untersuchungen, herausgeg. von Karstcn,
1866.

FISCHER u. WALDHEIM, Jahrb. f. wiss. Botanik von Pringsheim,
Bd. 7, 1869.

BEES, Die Rostpilzformen der deutscheii Coniferen. Halle, 1869.

HARTIG, Wichtige Krankheiten der Waldamne.
— , Untersuchnngen ans dem forstbotan. Iiist. zu Miinchen,

I.— III.
— -, Ueber die durch Pilze bedingtcn Pflanzeiikrankheiten.Vortrage

im arztlichen Verein zu Miinchen, 1881.
— , Die Zerstorung des Bauholzes durch Pilze, I. Berlin, 1885.

SORAUER, Landwirthsch. Versuchsstationen, Bd. 25, 1880. Botan.
Zeitung, 1882.

WOLFF, Thiel's Landw. Jahresber, 1872.

MOULD FUNGI AS ANIMAL PARASITES.
In Caterpillars.

ROBIN, Histoire naturelle des vegetaux, qui croissent sur 1'honime

et les animaux vivans. Paris, 1848, 1853.
DE BARY, Zur Kenntniss insectentodtender Pilze, Botan. Zeit.,

1867, 1869.

BAIL, Ueber Pilzepizootien der forstverhereenden Raupen. Danzig,
. 1869.

In Flics.

GOTHE, Hefte zur Morphologic, I. 292.

NEES Y. ESENBECK, Nov. Act. Acad. Caes. Leop. Car. Nat. Cur.,

Bd. 15, 1831.
COHN, Empusa muscae u. die Krankheit der Stubenfliege. Breslau,

1865.

LEBERT, Abh. der naturforsch. Ges. in Zurich, 1856.
FRESENIUS, Abh. d. Senckendorff'schen. naturf. Ges., Bd. 2, S. 201.
BREFELD, Unters. iiber die Entwickl. der Empusa muscae and

Emp. radicans. Halle. 1871.
PEYRITSCH, Sitzungsber der k. k. Akad. der Wiss. in Wien., Bd. 64,

1871.

MTERATURK. 7

In Man and Higher Animals.
ROBIN, 1. c.

FRIEDREICH, Virch. Archiv, Bd. II.
COHNHEIM, Ibid., Bd. 33.
FURBRINGER, Ibid., Bd. 76.
ROSENSTEIN, Berl. klin., Wochenschr., 1867.
WAGNER, Jahrb. f. Kinderheilkunde, 1868.
ZENKER, Jahresb. der Ges. fiir Natur- u. Heilk. in Dresden, 1861 —

62.

GROHE, Berl. klin. Woch., 1871.
BLOCK, Ueber Pilzbildung in thierischen Geweben. Diss. Stettin,

1871.

LEBER, Aerztl. Intelligenzbl., 28 Jahrg., Nr. 7.
BEZOLD, In den Vortragen im arztlichen Verein zuMiinchen, 1881.
KITT, Deutsche Zeitschr. f. Thiermedicin., Bd. 7.
GRAWITZ, Yirchow's Archiv, Bd. 70, 1877 ; Bd. 81, 1880.

— , Berl. klin. Woch., 1881, Nr. 45 u. 46.
KRANNHALS, St. Petersb. med. Woch., 1881.
SIEBENMANN, Die Fadenpilze. Wiesbaden, 1883 (See there the

older literature).

GAFFKY, Mittheilungen des Kais. Ges.-Amts., 1 Bd., S. 80.
LOFFLER, Ibid., S. 134.
KOCH, Berl. klin. Woch., 1881, Nr. 52.
LEBER, Berl. klin. Woch., ]882, Nr. 2.
LICHTHEIM, Berl, klin. Woch., 1882, Nr. 9 u. 10.
— , Ueber pathogene Mucorineen. Zeitschr. f. klin. Medicin.,

Bd. 7, H. 2.
SCHUTZ, Ueber das Einclringen von Pilzsporeii in die Athmungs-

wege. Mitth. a. d. Kais. Ges.-Amt., Bd. II.
— , Ueber den Pilz des Hiihnergrinds, Ibid., Bd. II.
HUCKEL, Zur Kenntniss der Biologic von Mucor corymbifer.

Beitr. zur path. Anat. u. Phys. von Ziegler u. Nauwerck., Heft.

I. Jena, 1884.

KLEINHANS, Die parasitiiren Hautaffectionen. Erlangen, 1864.
PICK, Unters. iiber die pflanzlichen Hautparasiten. Verhandl. d.

zoolog. botan. Ges. in Wien., Bd. 15, 1865.
PEYRITSCH, Beitrag. zur Kenntniss des Favus. Wien. inedicin.

Jahrb., Bd. 17, 1869.
BIZZOZERO, Ueber die Mikrophyten der normalen Oberhaut dea

Menschen. Virch. Arch., 98.

BABES (Oidium subtile cutis) Biolog. Centralbl., Bd. 2.
FRIEDREICH, Virchow's Arch., Bd. 30, 1864.

; LITERATURE,

ENGLISCH, Centralbl. f. Chirurgie, Bd. 15, 1883 (Schimmelpilze an

dexn Praeputium von Diabetikern).
BEHREND, Herpes tonsurans u. Favus. Viertelj. f. Dermatol u.

Syphilis, 1884.

KUNDRAT, Ueber Gastro-enteritis favosa. Wien. medic., Bl., Nr. 49.
BAUMGARTEN, Die pathogenen Hyphomyceten. Deutsche Medicinal -

Zeitung, 1874.— Berl. klin. Woch., 1882.
BALZER, Contribution a 1'etude de 1'erytheme tricophytiquo

(Herpes circimiatus), Arch, de Phys., 1883, Bd. 1.
ROECKL, Ueber Pncumonomykosen. Deutsche Zeitschr. f. Thiermed.

X., S. 122.

ACTINOMYCES.

BOLLINGER, Centralbl. f. d. Med. Wissensch., 1877.

PONFICK, Die Actinomykose. Berlin, 1881 (See there the older

literature) .
ISRAEL, Virchow's Arch., Bd. 74.— Bd. 78.— Bd. 95 u. 96.

Klinische Beitrage zur Kenntniss der Actinomykose des

Menschen. Berlin, 1885.

JOHNE, Deutsche Zeitschr. f. Thiermed., 1881.
HINK, Centralbl. f. d. med. AYiss., 1881, 1882.
PFLUG, Centralbl. f. d. med. Wiss., 1882.
G-ANNET, Boston Med. and Surg. Journ., 1882.
FLEMING, Actinomycosis, London, 1883.
TREVES, Lancet, 1884, p. 107.
FIRKET, Rev. de Med., Paris, 1884.
PUSCH, Arch. f. wiss. u. gr. Thierheilk, 1883.
BANG, Tidskrift far Veterinaerer, 1883. Ref. in Fortschr. d.

Medicin, II., Heft 6.

ZEMANN, Wien. Med. Jahrb., 1883, S. 477.
VIRCHOW, Virchow's Archiv, Bd. 95.
MITTELDORPF, Deutsche Medic. Woch., 1884.
KARSTEN, Ibid., 1884.
CHIARI, Prager med. Woch., 1834, N"r. 10.
BOSTROM, Verh. d. Congr. f. innere Med. Wiesbaden, 1885.
MAGNUSSEN, Beitrage zur Diagnostiku. Casuistik der Actinomykose.

Dissertation. Kiel, 1885.

BUDDING FUNGI -YEAST.
(For Fermentation, see p, 45.)

CAGNIARD-LATOUR, Memoire sur la fermentation vineuse. Ann. de.

chim. et de phys., 2 ser., T. 68, p. 206.
SCHWANN, Annal. d. Phys. u. Cbemie., 1837, T. 41, p. 184.

WTERATUKE. 1)

KUTZING, Journ. f. prakt. Chemie., Band 11, S. 385.
REES, Botan. Unters, iib. d. Alkoholgahrungspilze. Leipzig, 1870,
— , Ueber den Soorpilz. Sitz-ber. der phys. med. Ges. zu Erlangen,
• Juli, 1877, u. Januar., 1878.
BOXORDEX, Abh. der naturf. Ges. zu Halle, 1864.
CIENKOWSKI, Die Pilze der Kahmhaut. Melang. biolog. Acad. Imp.

de St. Petersbourg, T. 8.

GRAWITZ, Virchow's Arcli., Bd. 70, 1877, and Bd. 73, 1878.
PASTEUR, Memoire stir la fermentation alcoolique. Ann. Chim.

Phys, T. 58.

— , Etudes sur la biere. Paris, 1876.
SCHUTZEXBERGER, Unters. uber die Bierhefe. Ber d. Chem. Ges, 27,

S. 192. Compt, rend, 1879, p. 383.
FITZ, Ber d. Chem. Ges, Bd. 6, 1873.
BREFELD, Mueor racemosus und Hefe. Flora, 1873.
— , Thiel's Landw. Jahrb, 1875—1878.
— , Botanische Unters. liber Hefepilze (Leipzig, 1883).
FISCHER, Die systematische Stellung der Hefepilze. Biolog.

Centralb, Bd. 4, 1884.

HAIXSEX, Meddedelser fra Carlsberg-Laboratoriet, Band I.
— , Botan. Centralb, Bd. 17.
— , Neue Untersuchungeii iiber Alkoholgahrungspilze. Ber. d.

deutsch. botaii. Gesellsch, 1884, Bd. II. — Zeitschr. f. d. ges.

Brauwesen, 1884.
BOHX, Article " Soor " in Gerhardt's Handb. d. Kinderkrankheiten.

Tiibingcn, 1880.
KEHRER, Ueber den Soorpilz. Heidelberg, 1883 (See there the

older literature).
MARTIN, Soor beim Truthahn. Jahrb. d. k. Theierarzneisch. zu

Miinchen, 1882—1883.
PLAUT, Beitrag zur systematischen Stellung des Soorpilzes.

Leipzig, 1885.
PFELFFER, Ueber Sprosspilze in der Kalberlymphe. Weimar, 1885.

GENERAL LITERATURE ON BACTERIA AND
INFECTIVE DISEASES OF WOUNDS.

KOCH, Wundinfectionskrankheiten. Leipzig, 1878. — Mittheil. d.

Kais. Ges.-Amts, Bd. I.
WOLFF, Virchow's Arch, Bd. 81, Bd. 92.
PERRET, De la Septicemie. Paris, 1880.
SEMMER, Virchow's Archiv, Bd. 83.
RIXDFLEISCH, Lehrb. der pat hoi. Gewebelehre, 1 Auf. 1866, S. 204^

10 LITERATURE.

vox RECKLINGHAUSEN, Verb, der Wiirzb. phys.-med. Ges., 1871.
BiRCH-HmscHFELD, Untersuchungen liber Pyamie. Leipzig, 1878.
KLEBS, Beitr. zur. pathol. Anat. der Scbusswundeii. Leipzig, 1872.
— , Arcb. f. exper. Pathol. u. Pharmakol. Leipsig, Band I., 187M.
III. 1875, IY. 1875, Y. 1876, X. 1879.
— , Centralb. f. d. med. Wissenscb. Berlin, Bd. 6, 18G8.
BiRCH-HiRSCHFELD, References in Scbmidt's Jahrbuchern, Bd. 166,

S. 169, as to tbe literature during the years 1872—1874.
YIRCHOW, Embolie u. Infection. Gesamm. Abbdl. 1857, S. 656.
WALDEYER, Zur pathol. Anatomic der Wundinfectionskrankheittii.

Yirchow's Arch., Bd. 40, 1867.
— , Mikrokokkencolonieii in den parenchymatiscbeii Organen.

Yortrag. i. d. med. Ges. zu Breslau, 4 Aug., 1871.
STICK, Charite-Annal., 1852.
WEBEE, Deutsche Klinik., 1864-65.
BILLROTH, Arch. f. klin. Chir., Bd. 6, 265.
BILLROTH UND EnRLiCH, Ibid., Band 20. 1876.
BILLROTH, Coccobacteria sept. Berlin, 1874.
FISCHER, Centralblatt f. d. med. Wissench., 1868.
TIEGEL, Ueber den fiebererregenden Eigenschaften des Microsporon
septicum. Bern. 1871, Diss.
— , Yirchow's Archiv, Bd. 60, 1874.

ZAHN, Zur Lehre von den Entziindungeii, &c. Heidelberg, 1872.
HEIBERG, Die puerpalen u. pyamischen Processe. Leipzig, 1873.
OUTH, Yirchow's Arch., Bd. 59, 1874.
— , Arch. d. Heilk. Leipzig, Bd. 13, 1872.
— , Yirchow's Arch., Bd. 58, 1873.

— , Arch. f. wissensch. u. prakt. Thierheilk. Bd. 3, 1877.
— , Berliner klin. Wochenschr., Bd. 9, 1872.
COZE ET FEI/TZ, Recherches experimentales. Strassburg, 1866.
LACASSAGNE, De la putridite morbide et de la septicemie. Paris,

1872.

DAVAINE, BOULEY, BE"HIER, YULPIAN, COLIN, HAYEM, Bull. d. 1'Acad.
de med., 1872-1873.— Ibid., 1862, 1879, 1881.
— , Compt. rend. Soc. de biol. Paris, 1874.
NASSILOFP, Yirchow's Arch., Bd. 57, 1873.
KIJKRTH, Zur Kenntniss der bakterischen Mykoseii. Leipzig, 1872.

-, Med. centralblatt. 11, S. 8, 32. 1873.
— , Yirchow's Arch., Bd. 57, 1873.
— , Ibid., Bd. 77, 1879.
, Ibid., Bd. 80, 1880.
LEBEE, Med. Centrlbl., Bd. 11, 1873.
HEIBERG, Med. Centrlbl., Bd. 12, 1874.

LITERATURE; II

, Med. Centrlbl., 1873, 45.
HUETER, Allgem. Cliirurgie. Leipzig, 1873.

— , Deutsche Zeitschr. f. Chirg., 1872.
HUBER, Deutsches Archiv f. klin. Med. Leipzig, Bd. 25.
LANDAU, Arch. f. klin. Chir. Berlin, 27, 1874.

— , Verhandl. d. deutschen Gesell. f. Chirurgie, Band 2, 1878.
SCHULLER, Deutsche Zeitschr. f. Chir. Leipzig, Bd. 6, 1875.
NEPVEU, Ueber die Bedeutung der niederen Organismen bei

chirurgischen Affectionen. Gaz. de Paris, 1875.
FELTZ, Compt. rend. Acad. d. sc. Paris, T. 76, 1873.— Ibid.,

T. 79, 1874.
LETZERICH, Arch. f. exper. Path. u. Pharmakol. Leipzig, Band 7,

1877.

— , Virchow's Arch., Bd. 68, 1876.

CHAUVEAU, Compt. rend. Acad. d. sc. Paris, T. 76, 1873.— Ibid.,
T. 92, 1881.

— , Gaz. hebd. de med. Paris, T. 12, 1875.
— , Gaz. d. hop. Paris, 1881.
COLIN, Bull. Acad. de Med. Paris, T. II., 1873.— Ibid., T. 4, 1875.

— , Ibid., T. 7, 1878.— Ibid., T. 8, 1879.— Ibid., T. 10, 1881.
BJ-:UT, Compt. rend. Soc. de biol. Paris, T. 2, 1875.— Ibid., T.

5, 1878.— Ibid., T. 7, 1880.

BALFOUR, Edinburgh Med. Journ., Vol. 23, 1877.
PASTEUR, Bull. Acad. de med., Paris, T. 9, 1880.
— , Compt. rend. Acad. d. sc. Paris, T. 85, 1877.— Ibid., T. 87,

1878.

PUKY, Virchow's Arch., Bd. 69.
BECK, Rep. Med. Off. Local Gov. Board, 1879.
TSKAEL, Virchow's Archiv, Bd. 74, 1878.

— , Berl. klin. Wochenschr., Bd. 15, 1878.
LrrrEN, Berl. klin. Wochenschr., 1878.

— , Zeitschr. f. klin. Med., 1880.
DIJYSDALE, Pyrexia. London, 1880.
TILLMANNS, Vcrhdl. d. deutschen Gcsellsch. f. Chirurgie, Band 7,

1878.

TOUSSAINT, Compt, rend. Acad. de sc. Paris, T. 91, 1880.
TVXDALL, Essays on the Floating Matter of the Air in relation to

Putrefaction and Infection. London, 1881.
ZWEIFEL, Zeitschr. f. physiol. Chemie. Strassburg, Band 6,

1882.

MIKULICZ, Arch, fur klin. Chir. Berlin, Band 22, 1878.
LISTER, Lancet, Vol. 2, 1867.
— , Med. Times and Gazette, Vol. 2, 1877.

12 LITERATURE.

LISTER, Quart. Journ. Micr. Sc. London, Vol. 13, 1873. — Ibid., Vol.

18, 1878.— Ibid., Vol. 21, 1881.

KLEIN, Rep. Med. Off. Local Board (1881) London, 1882.
BRAIDWOOD AND VACHER, Brit. Med. Journ., Vol. I., 1881.
OERTEL, Zur Aetiologie der Infectionskrankheiten, 1881.
OGSTON, Brit. Med, Journ., Vol. I., 1881.

— , Journ. of Anat. aud phys., Vol. 17, 1882.
RAYNAUD, Bull. Acad. de med. Paris, T. 10, 1881.
ROSZAHEGYI, Practitioner, London, Vol. 38, 1882.
ROSENBERGER, Verhdl. der phys. med. Ges. zu. Wiirtzburg, 1882.
STERNBERG, Am. Journ. Med. sc. Philad., Vol. 84, 1882.

-*— i John Hopkins Univ. stud. biol. lab. Baltimore, Vol. 2, 1882.
NAUNYN, Berl. klin. Wochenschr., Bd. 20, 1883.
EWART, Proc. Roy. Soc. London, Vol. 32, 1881.
(TUSSENBAUER, Sephthamie, Pyohamie, undPyosephthamie. Deutsche

Chirurgie von Liicke und Billroth. Stuttgart, 1882.
DOWDESWELL, Proc. Roy. Soc. London, Vol. 34, 1883.

— , Quart, Journ. Micr. Sc. London, Vol. 18, 1878.
CORNIL ET BABES, Arch, de physiol. norm, et path., T. 2, 1883.
BABES, Compt. rend. Acad. de sc. Paris, T. 97, 1883.
ARLOING, Compt. rend. Acad. de sc. Paris, T. 98, 1884.
CHEYNE, Trans, path. Soc. London, Vol. 30, 1879.— Ibid., Vol. 3.",

1884. Brit. Med. Journal, 1884, 1886, 1888, &c.
SUTTON, Trans. Path. Soc. London, Vol. 34, 1813.
STRANGE, Brit. Med. Journ., Vol. 2, 1883.
STEVENS, Glasgow Med. Journ., Vol. 22, 1884.
ROSENBACH, Mikroorganismen bei den Wundinf ektionskrankheiten

des Menschen. Wiesbaden, 1884.
PASSET, Fortschritte d. Medicin, Bd. 3, 1885.
ARLOING, Recherches sur les septicemies, Lyons, 1884.

SUPPURATIVE INFLAMMATION OF THE CELLULAR

TISSUE.

PASTEUR, Le furoncle. Bull, de 1'Acad. de Med., Ser. 2, T. 9,

1880.

LOWENBERG, Le furoncle de 1'oreille. Paris, 1881.
ROSENBACH, Mikroorganismen bei den Wuiidinfectionskrankheiten

des Menschen. Wiesbaden, 1884.
PASSET, Ueber Mikroorganismen der eitrigeii Zellgewebsentziin-

dung des Menschen. Fortschritte d. Med., 1885, No. 2.
GARRE", Zur Aetologie acut eitriger Entziindungen. Fortschritte

de Med., 1885, 165.

LITERATURE. 13

UUCLAUX (Bouton d'Alep. et de Biskra), Bull, de 1'Acad. de

medecine, 1884, 10th June.
CHEYNE, Brit. Med. Journal, 1884, 1886, 1888.

OSTEOMYELITIS.

COLLMANN, Bakterien im Organismus eines an einer Vei letzung am

Oberschenkel verstorbenen Madchens. Gottingen, 1873.
EBERTH, Virchow's Arch., Bd. 65, 1875.
FRIEDMANN, Fall von primarer infectioser Osteomyelitis. Berl.

klin. Wochenschr., XII. 4, 5, 6, 1876.
SCHULLER, Zur Kenntniss der Mikrokokkeii bei acuter infectioser

Osteomyelitis. Mikrokokkenherde im Gelenkknorpel, Cen-

tralbl. f. Chir., 1881., No. 12.
BECKER, Vorl. Mitth. iiber den die acute infectiose Osteomyelitis

erzeugenden Mikroorganismus., D. Med. Wochenschr., Nov.,

1883.
KRAUSE, Ueber einen bei der acuten infectiosen Osteomyelitis vor-

kommenden Mikrokokkus, Fortschr. d. Med., Bd. 2, 1884.
ROSENBACH, Vorl. Mitth. iiber die acute Osteomyelitis beim Men-

schen erzeugenden Mikroorganismen. Centralbl. f. Chir., 1884,

No. 5.

PEYROUD, Compt. rend., 1884, October.
HODET, Etude experimentale sur rosteomyelite infectieuse.

Compt. rend., T. 99, p. 569.

ERYSIPELAS.

HECKLINGHAUSEN u. LANKOWSKI, Ueber Erysipelas. Virchow's

Archiv, B. 60, 1874.

LUKOMSKY, Virchow's Archiv, Bd. 60, 1874.
HL-TER, Med. Centralbl., No. 34, 1868.
ORTH, Archiv f. exper. Pathol. u. PharmacoL, Bd. 1, 1873.
RAYNAUD, Union Med., Paris, 1873.
TROSIER, Bull. Soc. anat. de Paris, 1875.
BAADER, Zur Aetiologie des Erysipels. Schweiz. naturf. Gresellsch.

Basel, 1875.

KLEBS, Archiv f. exper. Pathol u. Pharmakol, Bd. 4, 1875.
EHRLICH, Langenbeck's Archiv, Bd. 20.
TILLMANNS, Verhandl. d. deutsch. Ges. f. Chirurgie, 1878.
— , Experimentelle u. anatomische Unters, &c., Archiv f. k^in.

Chirurgie. Band 23, 1879.
WOLFF, Virchow's Archiv, Bd. 81.

14 LITERATURE.

, Reserches cliniques et experimentalcs sur la pathogvnie
d. 1'erysipele. Paris, 1881.

FEHLEISEN, Die Aetiologie des Erysipels. Berlin, 1883.
— , Deutsche Zeitschr. f. Chirargie. Band 16, 1882.
--, IJeber den Erysipelaspilz. Wiirzburger phys. med. Gcs.

Aug., 1881.
JANICKE.U. NEISSER, Exitus lethalis nach Erysipelas. Centralbl.

f. Chir., 1884, No. 25.

RHEINER, Beitr z. path. Anat. des Erysipels bei Gelegenheit der
Typhusepid. in Ziirich, 1884. Virchow's Arch., Bd. 100, Heft 2.

EMBOLI AND METASTASES.

BURKART, Ein Fall von Pilzembolie. Berl. klin. Wocheiischr..

XI., 1874.

MARTINI, Deutsche Ges. f. Chirurgie, 19 April, 1873.
ORTH, Mitth. ii. d. Mikrokokkenembolieen in den Capillarcn.

Sitzung der Niederrh. Ges. f. Natur- u. Heilkunde. Bonn.

Marz., 1879.

PERLS u. WEISSGERBER, Archivf. exper. Pathol. n. Pharmakol.,Bd.O.
RECKLIXGHAUSEN und LANKOWSKY, Verhandl, der physik. mod.

Ges. Wiirzburg, Bd. II., 1871.
WASSILIEFF, Beitr. zur Frage iiber die Bedinguugen zur Entwick-

lung von Mikrokokken in den Blutgefassen. Centralbl. f. d.

med. Wissensch., Nr. 52, 1881.
PARENSKI, Ueber embolische Darmsgeschwiire. Med. Jahrbiicliej'.

III. Heft, 1876.
RIBBERT, Eine mikroparasitare Invasion der ganzen Geliirnrinde.

Virchow's Arch., Bd. 80.

LETZERICH, Encephalitis bacteritica. Virchow's Arch., Bd. 65.
FOA, Mycose d. Pancreas. Giorn. Internal;, della sc-ient. medica, III..

1841.
LETZERICH, Ueber Mycosis oesophagi. Arch. f. exper. Pathol.,

Bd. 7, 1877.
LITTEN, Einige Fiille von mycotischer Nicrenerkrankung. Zeitschr.

f. klin. Med., 6.
KRAUSE, Ueber die acute katarrhal. Gelenksentziindung bei

klcinen Kindern und den dabei vorkommenden Kettenkokkus.

Berl. klin. Wochenschr., 1884, Nr. 43.
HEUBNEB u. BAHRDT, Zur Kenntniss der Gelenkeiterungen bei

Scharlach. Berl. klin. Wochenschr., 1884, Nr. 44.
FLEISCHHAUER, Acuter Geleiikrheumatismus mit. miliaren Absccs-

sen. Virchow's Arch., Bd. 62, 1875.

LITERATURE. 15

PUERPERAL FEVER.

MAYRHOFEU, Vibrionen als Kraiikheitsursache des Puerperalfiebers.

Monatsschr. f. Geburtsk. u. Fraueiikrankheiten. Bd. 25, 1865.
\VALDEYER, Ueber Vorkonimen von Bakterien bei der diphtheri-

tischen Form des Puerperalfiebers. Arch, fiir Gynakologie,

1872, III.
IIciBERG, Die puerperaleii und pyamischen Processe. Leipzig.

1873.
— , Om pyaemia og puerperalfieber. Norsk. Magaz. for

Lagevelsk, Bd. 11.

ORTH, Virchow's Arch., Bd. 58, 1873.
LAFFTER, Gehirnerweichungsherde durch Mikrokokkenembolieen bei

puerperaler Pyamie. Bresl. artztl. Ztg., 1879.
KAREWSKI, Exper. Unters. liber die Einwirkung puerperaler

Secrete auf den thierischen Organismus. Zeitschr. f. Geburtsh.

u. Gynakologie, Bd. 7, 1881.
DOLERIS, La fievre puerpenile et les organismes infect. Paris,

1880.

PAST BUR, Bull, de 1'Acad. de med., 1880, T. 9.
AUFRECHT, Die exper. Erzeugung der Endometritis diphtherica

puerperalis. Naturforsch. Versamml., 1884.

ENDOCARDITIS.

MAIKR, Virchow's Ai-ch., Bd. 62.

EBERTH, Virchow's Arch., Bd. 57, 62, 65.

KOESTER, Virchow's Arch., Bd. 72.

BiRCH-HiRSCHFELD u. GfiRBER, Archiv d. Heilkunde, 1876.

LITTEX, Zeitschr. fiir klin. Med., Bd. 2.

WEIQERT, Virchow's Arch., Bd. 84.

O. ROSEN BACH, Ueber artificielle Herzklappenfehler. Archiv fiir

exper. Pathol., Bd. 9, 1878.
HEIBERG-HJALMAR, Virchow's Arch., Bd. 56.
WEDEL, Berl. klin. Wochenschr., 1877.
KLEBS, Archiv f. exper. Pathol., Bd. 9.

HAMBURG, Ueber acute Endocarditis, Berlin, Inaug.-Diss., 1880.
LEYDEX, Zeitschr. f. klin. Medicin., 1881.
BRAMWELL, Diseases of the Heart. Edinburgh, 1884.
OBERBECK, Casuistische Beitrage zur Lehre von der Endocarditis

nlcerosa. Inaug.-Diss. Gottingen, 1881.

KUNDRAT, Sitz.-Ber. d. Kais. Acai. d. Wissensch. zu Wien, 1883.
WYSOKOWITSCH, Centralbl. f. d. med. Wissensch., 1885, Nr. 33.

T6 LITERATURE.

MALIGNANT CEDEMA AND TETANUS.

DAVAIXE, Ball, de 1'Acad. de Med., 1862, Sept,

PASTEUR, TJeber d. Vibr. septique. Bull de 1'Acad. de Med., 1877,

1881.

KOCH, Mitth. aus dem Ges.-Amt., I., S. 54.
GAFFKY, Ibid., S. 88.

BRIEGER, u. EHRLICH, Berl. klin. Wochenschr., Nr. 44, 1882.
LEBEDEFF, Versiiche uber Desinfection bei malignen Oedembacillen.

Arch, de phys. norm, et path., 1882, 6.

TRIFAUD, De la gangrene gazeuse foudroyante. Rev. de chir., III.
CHAUVEAU ET ARLOING, Bull, de 1'Acad. de Med., 1884, 6 May— 19

August.
.LUSTIG, Zur Kenntniss bakteriamischer Erkrankungen bei Pferden

(Malignes Oedem). Jahresber. d. K. Thierarzneischule zu Han-
nover, 1883-4.
KITT, Unters. iiber malignes Oedem. und Rauschbrand bei Haust-

hieren Jahresber. der K. Thierarzneischule zu Miinchenr 1883-4,
HESSE, W. and R., Ueber Ziichtung der Bacillen des Malignon

Oedems. Deutsche med. Wochenschr., Nr. 14, 1885.
CARLE & RATTONE, Studio sperimentale sull' etiologia del tetano.

Giorn. della R. Acad. di Medicina di Torino, Marz, 1884.
NICOLAIER, Deutsche med. Wochenschr., 1884, Nr. 52.
VOGEL, Drei Falle von infectiosem Tetanus. Deutsclie med.

Wochenschr., 1885, Nr. 31.

PUTRID INTOXICATION, PTOMAINES.

HKMMER, Exper. Studien. uber d. Wirkung faulendei- Stoffe.

Miinchen, 1866.
Sen \VENINGER, -Ueber d. Wirkung faulender org. Substanzen, &v.

Miinchen, 1866.
v. RAISON, Zur Kenntniss der putriden Intoxication, <&f. Diss.

Dorpat, 1866.
FRESE, WEIDENBAUM, SCHMITZ, PETERSSKX, SCHMIDT, v. BBKHM,

Dissertationen iiber d. putride Gift, &c. Dorpat, 1866 — 72,
HKRGMANN, Das putride Gift, &c. Bd. I. Dorpat, 1866.

— , Deutsche Zeitschr. f. Chirurgie, Bel. I., 1872.
BERGMANN u. SCHMIEDEBERG, Med, Centralbl., 1868, S. 397.
ZULZER U. SONNENSCHEIN, Berl. klin. Wochenschr., 1869.
PAXUM, Virchow's Arch., Bd. 60, 1874.

cii, Exper. Studien, lib. d. Verbreitungd. Faulnissorganismen,
Erlangen, 1874.

LITERATURE. 17

BAVITSCH, Zur Lehre von der putriden Infection, &c. Berlin, 1872.
HILLER, Centralbl. f. Chirurgie, 1876.
— , Die Lehre von der Faulniss. Berlin, 1879.
NENCKT, Ueber die Zersetzung der Gelatine, &c. Bern, 1876 —

Journ. f. prakt. Chem., Bd. 26, 1882.
CLEMBNTI & THIN, Unters. lib. d. putride Infection. Wien. med.

Jahrb., 1873, S. 292.

KEHRER, Archiv f. exper. Pathol., Bd. I., 1874.
BLUMBERG, Bxperimenteller Beitrag zur Kenntniss der putriden

Intoxication. Virch. Arch., Bd. 100, S. 377.
SELMI, Chemische Ber., Bd. 6, 7, 12. — Sulle ptomaine ad alcaloide

cadaverici. Bologna, 1878.
BOUCHARD, Compt. rend, de Biol., 1882, Aug.
GAUTIER, C. B. de 1'Acad. d. sc., T. 94, 2. '

— , Journalde 1'anat. et de la phys., T. 17.
GAUTIER ET ETARD, C. B. de 1'Acad. de sc., T. 94.
BROUARDEL ET BOUTMY, C. B. de 1'Acad. de sc., T. 92, p. 1056.

— , Annal. d'hyg. publ., 3 ser., T. I.
TANRET, Ibid., 92 T., publ. 1163.
SCHIPPER, Arch. f. Anat. u. Physiol. Abtheil., 1882.
Bocci, Ctrlbl., f . d. med. Wiss, 1882.

GROEBNER, Beitrage z. Kenntniss Der Ptomaine. Dorpat, 1882.
GUARESCHI ET Mosso, Arch. ital. de Biolog., 1883.
SALKOVVSKI E. & A., Ber. d. Chem. Ges., Bd. 16.
SALOMONSON, Nordisk. Archiv, Bd. 13.
MAAS, Ueber Faiilnissalkaloide des gekochten Fleisches und des

Fischfleisches. Fortschr. d. Med., II. 729.
VANDEVELDE, Les ptomaines. Arch. d. Biol. par van Beneden. Gent,

1884.

WILLGERODT, Ueber Ptomaine. Freiburg, 1884.
HUSEMANN, Arch. d. Pharmac, 1880, 1882, 1883.
KONIG, Massenerkrankung von Menschen nach dem Geiiuss von

Fleisch einer an piitrider Metritis verendeten Kuh (Putride

Intoxication). Ber. lib. d. Yeteriiiiir-Wesen im Konigreich

Sachsen, 1881.
BERGMANN & ANGERER, Das Verhaltniss der Fermentintoxication

zur Septicamie. "Wurtzbiirger Jubil Festschr., 1882.
SCIIMIEDEBERG u. HARNACK, Arch. f. exp. Pathol., Bd. 16.
BRIEGER, Zur Kenntniss der Faiilnissalkaloide. Zeitschr. f.

physiol. Chemie., Bd. 7, 1883.— Ber. d. Deutsch. Chem. Ges.,

1884, Bd. 17.
— , Ueber Spaltungsproducte der Bakterien, Zeitschr. f.

physiol. Chemie, 1884, Band 8, Heft 4.— Bd. 93 Heft 1.

2

18 LITERATURE.

BRIEGER, Ueber giftige Producte cler Faulnissbakterien. Berl.
klin. Wochenschr., 1884, No. 4.

— , Ueber Ptomaine. Berlin, 1885.

— , Weitere Untersuchungen iiber Ptomaine. Berlin, 1885.
BACKLISCH, Ber. d. deutsch. chem. Gesellsch, Bd. 18, 1885.
CAPPOLA, Arch, ital. de biolog., Bd. 4.
FOA & PELLACANI, Arch. ital. de biolog., Bd. 4.
OFFINGER, Die Ptomaine. Wiesbaden, 1885.
OTTO, Anleitung zur Ausmittelung der Grifte. Braunschweig, 1884.

DIPHTHERIA.

OERTEL, Deutsch. Arch. f. klin. Med., Bd. 8, 1871.

— , von Ziemsscn's Handb. der spec. Pathologic u. Therapie,
Band II.

— , Zur Aetiologie der Infectionskrankheiten. Miinchen, 1881.
HUETER & TOMASSI, Centralbl. f . d. med. Wissensch., 1868.
TRENDELENBURG, Arch. f. klin. Chirurgie, Bd. 10.
NASSILOFF, Virch. Arch., Bd. 50.
ZAHN, Beitrage zur Pathol. u. Histol. der Diphtheric. Leipzig,

1878.

CORNIL, Arch, de physiol., 1881.
KLEBS, Arch. f. exp. Pathol., Bd. 4, 1875.
LETZERICH, Virchow's Arch., Bd. 52, 55, 61, 68.

— , Mikrochemische Erscheinungen des Diphtheritispilzes. Berl.
klin. Wochenschrift, XI., 1874.
EBERTH, Der diphtheritische Process. Med. Ctrlbl., XI., No. 8,

1873.

EVERETT, Med. and Surg. Reporter. Philadelphia, 1881.
WOOD AND FORMAD, Nat. board of health Bull. Wash., 1882.
TALAMON, Bull, de la soc. anat. de Paris, T. 56, 1881.
SALISBURY, Gaillard's Med. Journ. New York, 1882.
FRIEDBERGER, Ueber Croup u. Diphtheritis beim Hausgefliigel.

Deutsche Zeitschr. fiir Thiermed. u. vergl. Pathol., 1879.
NICATI, Compt. rend., 1879, Bd. 88.

NEUMAYER, Neue Thesen zur Diphtheritisfrage. Freising, 1880.
FURBRINGER, Virch. Arch., Bd. 91, 1883.
HEUBNER, Die experimentelle Diphtheric. Leipzig, 1883.
(IKKHARDT u. KLEBS, Verhandl. d. Congresses f. inn. Med. Wies-
baden, 1883.

LOEFFLER, Mittheil. a. d. Kais. Ges.-Amt., Bd. II.
FRANCOTTR, La Diphtheric. Liege, 1883.

LITERATURE. 19

EMMERICH, Ueber die Ursacheii der Diphtherie des Meiischen und

der Tauben. Deutsche med. Woch., 1884, S. 614.
— , Compt. Rendus et Memoires du V. Congres internal d'Hygeine.
la Haye, 1884, p. 247.

RLVOLTA, Die Diphtherie der Hiihner im Vergleich zu der des
Meiischen. Griornale de Anat. Fisiol. c Patol. delli anim., 1884.

GONORRHOEA, OPHTHALMOBLENNORRHCEA, AND
SYPHILIS.

BLENNORRH(EA.

XmssER, Centrlbl. f. d. medicin. Wiss., 1879, Nr. 28.

BoivAi, Ueber das Contagium der acuten Blennerrhoe. Allgem.

med. Centralzeitung, 1880, Nr. 74.

BOKAI AND FINKELSTEIN, Prager med. chir., Presse, 1880.
BUCKER, Ueber Polyarthritis gonorrhoica Diss. Berlin, 1880.
AUFRECHT, Pathologische Mittheilungen, 1881.
\Vri:iss, Le microbe du pus bleniiorrhagique. These de Nancy,

1880. Ann. de Dermatol., I., 1881.
HAAB, Corresp. f. Schweizer Aerzte, 1881.

— , Der Mikrokokkus der Blennorrhoea neoiiator. Weisbaden, 1881.
HiRSCiir5ER!i u. KRAUSE, zur Pathologic der ansteckenden Augen-

krankheiten. Centralblatt f. pract. Augenheilk, 1881.
KRAUSE, Die Mikrokokken der Blenorrhoea neonator. Ibid., 1882.
LKISTIKOW, Ueber Baktere in bei den venerischen Krankheiten.

Charite-annalen, 7 Jahrg., S. 750, 1882.
10 !\ LUND, Sur les microbes de la blennorrhagie. Haarlem, 1882. —

Ref. in Schmidt's Jahrbiichern, Bd. 197, S. 139.
13oc;aiART, Beit-rag z. Aetiologie und Pathol. des Harnrohren-

trippers. Viertelj. f. Dermatol und Syph., 1883. Sitzungsbericht

d. phys. med. Ges. zu. Wiirzburg. Sept., 1882.
MARTIN, Rech. sur les inflamm. metast. a la suite de la gonorrhee.

(ierieve, 1882.

ARXINII, Gonokokken bei Bartblinitis. Vierteljschr. f. Der-
matol. u. Syph. 1883, S. 371.
BSCHBAUM, Beitr. zur Aetiologie der gonorrh. Secrete. Deutsche

med. Woch., 1883, S. 187.

NEWBERRY, Maryland Med. Jourii. Febr., 1883.
CAMPONA, Italia Medica., 1883.
AUFRECHT, Mikrokokken i. d. iniieren Organen bei Nabelvenenent-

ziindung Neugeborener. Centralbl. f. d. med. Wiss., 1883,
. Nr. 16.

20 LITERATURE .

PETRONE, Sulla natura dell' artrite blennorragica Kivista clin.

1883, No. 2.

ZWEIFEL, Zur aetiol. der Ophthalmoblennorrhoea neonator. Arch.
' f. Gyn. XXII., S. 318.

BUMM., Gonorrhoe d. weibl. Genitalien. Ibid. XXIII., S. 328.
WELANDER, Sur les microbes pathogenes de la blennorrhagie.

Gaz. medicale, 1884, u. Nord. med. Arkiv. Bd. 16., Nr. 2.
LEOPOLD u. WESSEL, Beitr. z. Aetoil. u. Prophylaxe der Ophthal-

nioblennorlioea neonat. Arch. f. Gyn. XXIV., S. 92.
CHAMERON, Progres medical., 1884, 43.
STERNBERG, Med. news., Bd. 45, 1884, Nr. 16.
KAMMERER, Ueber gonorrh. Gelenkentziindung. Centra Ibl. f.

Chirurgie, 1884, Nr. 4.
K.RONER, Zur Aetiol. der Ophthalmoblennorrhoea neonator. Natur-

fosschervers. in Magdeberg, 1884, Arch. f. Gyn. XXY., S. 109.
SANGER, Ueber gonorrh. Erkrankung der Uterusadnexe. Ibid.,

S. 126.

OPPENHEIMER, Ibid., XXV., S. 51,
ERANKEL, Deutsch. med. Wochenschr., 1885, S. 22.
BUMM, Der Mikroorganisnius der gonorrhoischen Schleimhauter-

krankungen. Weisbaden, 1885.

LUNDSTROM, Studien liber Gonococcus. Dissert. Helsingfors, 1885.
E. FRANKEL, Mikrokokken bei Colpitis. Deutsche med. Wochen-
schr., 1885, No. 2.

SYPHILIS.

LOSTORFER, Arch. f. Dermat. u. Syph., 1872.

KLEBS, Arch. f. exp. Pathol., Bd. 10, 1879.

AUFRECHT, Centralbl. f. d. med. Wissensch., Bd. 19, 1881.

MARTINEAU ET HAMONIC, De la bacteridie syphilitique. Compt.

rend., 1882, p. 443.
MORISON, Maryland Med. Journ. Baltimore, 1882.— Ibid., 1883.—

Weiner Med. Wochenschr., 1883.
BiRCH-HiRSCHFELD, Bakterien in syphilitischen Neubildungen.

Centralbl. f. d. med. Wissensch., 1882, Nr. 33, u. 34.
PESCHEL, Centralbl. f. Augenheilk, 1882.
LE'TNIK, Wien. med. Wochenschr., 1883.
PETRONE, Gaz. medica Ital. Lomb., 1884.
TORNERY ET MARCUS, C. R. de 1'Acad.. d. sc., 1884, p. 472.
LUSTGARTEN, Wein. med. Wochenschr., 1884, Nr. 47.
KONIGER, Deutsche med. Wochenschr., 1884, S. 816.
LUSTGARTEN, Die Syphilisbacillen. Wien, 1885.
DOUTRELEPONT u. ScHUTZ, Deutsche med. Wochenschr., 1885, No. 19.

LITERATURE ; 21

DE GIACOMI, Neue Farbnngsmethode der Syphilisbacillen. Corre-

spondenzbl. f. Schweizer Aertze, Bd. 15.
GOTTSTEIN, Fortschr. d. med., Bd. 3, S. 543.
ALVAREZ ET TAVEL, Bull, d, 1'Acad. de med., 1885, August.

TUBERCULOSIS.

VILLEMIX, Etude sur la Tuberculose. Paris, 1868.
COHNHEIM, Uebertragbarkeit der Tuberculose. Berlin, 1877.
KLBBS, Arch. f. exp. Pathol. u. Pharmakol., Bd. 1., 1873.— Ibid.,
Bel. 17, 1883.

— , Virchow's Arch., Bd. 44, 1868.

TOUSSAINT, Compt. rend. Acad. de sc., Paris, T. 93, 1881.
KOCH, Die Aetiologie der Tuberculose. Berl. klin. Wochenschr.,

1882.

— , Mittheilungen aus dem Kais Ges.-Amt, Bd. II., 1884.
— , Kritische Besprechung der gegen die Bedeutung der Tuber-
kelbacillen gerichteten Publicationen. Deutsche med. Wochen-
schr., 1883, No. 10.

BAUMGARTEX, Berl. Klin. Wochenschr., Bd. 17, 1879.
— , Centralbl. f. d. med. Wissensch. Berlin, Bd. 19, 1881.— Ibid.,
Bd. 20, 1882.— Ibid., Bd. 21, 1883.— Ibid., Bd. 22, 1884.
— , Deutsche med. Wochenschr, Bd. 8, 1882.
— , Zeitschr f. klin. Med., Bd. 6, 1883.
AUFRECHT, Centralbl. f. d. med. Wissensch., Bd. 21, 1883.
BOLLINGER, Ibid., Bd. 21, S. 600, 1883.
OJIEYNE, Brit. Med. Journ., Vol. 1, 1883 and 1885.
— , Nature, Vol. 27, 1883.
— , Practitioner, London, Vol. 30, 1883.
BOCK, Virchow's Archiv, Bd. 91, 1883.
BALOGH, Wien. med. Wochenschr., 1882.
KiissNER, Beitr. z. Impftuberculose, Deutsche med. Wochenschr.,

1883, Nr. 36.

ANDREW, Lancet, Vol. 1, 1884.
BIEDERT, Virchow's Archiv, Bd. 98.
ALBRECHT, Arch. f. Kinderheilk, Bd. 5, 1884.
SCHOTTELIUS, Zur Kritik d. Tuberculosefrage. Virchow's Archiv,

Bd. 91, 1883.
TSCHERXTXG, Inoculationstuberculose beim Meiischen. Fortschr d.

Med., III., 65.
WAHL, Zur Tuberculosefrage, Deutsch. med. Wochenschr., 1882,

Nr. 46.

VAX ERMENGEM, Le microbe de la tuberculose. Ann. de la Soc. beige
de Microscopic, 1882.

22 LITERATURE.

KILLER, Deutsche med. Wochenschr., Bd. 8, 1882.
RAYMOND, Arch. gen. de med. Paris, Bd. 11, 1883,
BOULEY, La nature vivante de la contagion, contagiosite de la

Tuberculose. Paris, 1884.
BABES ET CORNIL, Note sur les bacilles de la Tuberculose. Journ.

de 1'Anat. et de la Physiol. norm, et patliol., 1884.
DETTWEILER, Berl. klin. Wochenschr., Bd. 21, 1883.
FORMAD, The bacillus tuberculosis. The Philad. Medical Times,

1882, Nov.

SPINA, Studien iiber Tuberculose. Wien, 1883.
CRAMER, Sitzungsber. d. phys. med. Soc. zu Erlangen, 1883.
MARCHAND, Deutsche med. Wochenschr., 1883, Nr. 15.
HERON, Lancet, Vol. 1, 1883.
GREEN, Brit. Med. Journ., Vol. 1, 1883.

— , Lancet, Vol. 1, 1882,— Ibid., Vol. 2, 1882.
KUNDRAT, Wien. med. Presse, 1883.
LANDOUZY ET MARTIN, Rev. de med., T. 3, 1883.
CHIARI, Wien. Med. Presse, 1883.

COCHET, Compt, Rend. Soc. de biol., Paris, T. 5, 1883.
PFEIFFER, Berlin klin. Wochenschr., Bd. 21, 1883.
DOUTRELEPONT, Die Aetiologie des Lupus vulgaris. Vierteljahrschr f .

Dermatologie u. Syphilis, 1884.
CORNIL & LELOIR, Recherches etc. sur la nature du lupus. Arch.

de physio] . norm, et pathol., 1884.

LEUBE, Sitzungsber. der phys. -med. Soc. zu Erlangen, 1883.
CREIGHTON, Brit. Med. Journ., Vol. 1, 1885.
— , Lancet, Vol. 1, 1885.
— , Trans. Path. Soc. London, Vol. 33, 1882.
DE'JE'RINE, Rev. de Med. Paris, T. 4, 1884.
GAFFKY, Verhalten der Tuberkelbacillen im Sputum. Mittli. a. d.

Kaiserl. Gesund-heitsamt, Bd. 2.
NEGRI, Colorations des spores dans les bacilles de la tuberculose.

Journ. de Microsc., T. 8, 1884.

RINDFLEISCH, Phys. med. Ges. zu Wiirzbnrg, 1882, Nr. 8.
LEYDEN, Klinisches iiber Tuberkelbacillen Zeitschr. f. klin. Med.,

1884, VIII.
ZIEHL, Bedeutung der Tuberkelbacillen fiir Diagnose und Prognose.

Deutsche med. Wochenschr., 1883, Nr. 5.
DIEULAFOY ET KRISHABER, Arch, de physiol. norm, et path., T. I.,

1883.
MALASSEZ ET VIGNAL, Ibid., T. II., 1883.— Compt. rend., T. 97,

1883. — Sur le microorg. de la tuberculose zoogloe'ique. Compt.

rend., T. 99, p. 200.

LITERATURE. 23

VIGNAL, Compt. rend. Soc. de biol. Paris, T. 5, 1883.

GIBBES, Lancet, Vol. 1, 1883.

EWART, Brit, Med. Jonrn., Vol. 1, 1882.

— , Lancet, Vol. 1, 1882.

EHRLICH, Deutsche med. Wochenschr., Bd. 8, 1882.— Ibid., Bd. 9, 1883.
LUSTIG, Ueber Tuberkelbacillen im Blut bei an allg. acuter

Miliartub. Brkrankten. Wien. Med. Wochenschr., 1884, Nr. 48.
LEVINSKY, Deutsche med. Wochenschr., Bd. 9, 1883.
LICHTHEIM, Fortschr. d. Med., Bd. 1, 1883.
WEST, Lancet, Vol. 1, 1883.

— , Trans. Path. Soc. London, Vol. 34, 1883.
DAMSCH, Die Impfbarkeit der Tuberculose als diagnostisches

Hiilfsmittel bei TJrogenitalerkraiikungen. Deutsches Arch. f.

klin. Med., Bd. 31.

— , Deutsche Med. Wochenschr., 1883, Nr. 17.
BABES, Der erste Nachweis des Tuberkelbacillus im Harn. Cen-

tralbl. f. d. med. Wissensch, 1883.
ROSENSTEIN, Centralbl. f. d. med. Wissensch, 1883.
JOHNE, Eiii zweifelh. Fall von congcnitaler Tuberculose. Fotschr.

d. Med. III., 198.

WEIGERT, Deutsche med. Wochenschr., 1883. Nr. 24, ff,
NAUWERCK, Ibid., 1883.
SCHAFFER, Ibid., NT. 21, ff.

CELLI & GUARNERI, Arch, pour les sciences medic. 1883.
FRANTZEL u. PALMERS, Berl. klin. Wochenschr., 1882, 1883.
DE GIACOMI, Fortschr. d. Med. I., 1883, S. 145.

SCHUCHARDT U. KfiAUSE, Ibid., I., 277.

MULLER, Ueber den Befund von Tuberkelbacillen bei fungoseii
Knochen u. Gelenk-affectionen. Centralbl. f. Chir., 1884, 3.

BROUILLY, Note sur le presence des bacilles dans les lesions
chirurgicales tuberculeuses. Rev. de chir., T. 3, 1883.

SCHLEGTENPAL, Fortschr. d. Med., I., 1883.

SCHILL u. FISCHER, Mitth. a. d. Kaiserl. Ges.-Amt., Bd. II.

SMITH, Bristol Med. Chir. Journ., Vol. I., 1883.

WILLIAMS, Lancet, Vol. 2, 1883.

VERAGUTH, Arch. f. exp. Path. u. Pharmakol. Leipzig, Bd. 16, 1883.

VOLTOLINI, Ueber Tuberkelbacillen im Ohr. Deutsche med.
Wochenschr., 1884, Nr. 31.

STRASSMANN, Virchow's Archiv, Bd. 96, 1884.

FUTTERER, Ueber das Vorkommen u. die Verfcheilung der Tuber-
kelbacillen in den Organen. Virch. Arch., Bd. 100, Heft 2.

PUTZ, Ueber die Beziehnngen der Tuberculose des Menscheii xu
der der Thiere. Stuttgart, 1883.

24 LITERATURE.

ESSER u. SCHUTZ, Zur Casuistik der Tuberculose bei Thiere

Arch. f. wiss. u. prakt. Thierheilk, XI.
BOLLINGER, Munch, arztl. IntelligenzbL, 1883, Nr. 16.
JOHNE, Die Geschichte der Tuberculose. Leipzig, 1883.
— , Zur Aetiologie der Hiilmertiiberciilose. Deutsche Zeitschr. f.

Thiermed. u. vergl. PathoL, Bd. X., S. 155.
— , Ber. iib. d. Yeterinarwesen im Konigr. Sachsen, 1883.
ZIPPELIUS, Wochenschr. f. Thierheilk., Bd. 20.
DEMME, 20 Jahresber d. Jenner'schen Kinderspitals. Bern. 1883.
LYDTIN, Badische thierarztl. Mittheil, 1883.
RIBBERT, Ueber d. Yerbreitungsweise der Tuberkelbacillen bei

Hiihnern. Deutsche med. Wochenschr., 1883, xir. 28.
BANG, Ueber Eutertuberculose der Milchkiihe. Deutsche Zeitschr.

f. Thiermed. u. vergl. PathoL, Bd. XI.
SUTTON, Trans. Path. Soc. London, Vol. 35, 1884.
WEICHSELBAUM, Wien. med. Jahrb. 1883 (Tuberkelbacillen im

Blut.).

MEISELS, Wien med. Wochenschr., 1884, Nr. 39 u. 40.
DOUTRELEPONT, Fall von Meningitis tuberculosa nach Lupus, Tuber-
kelbacillen im Blut. Deutsche med. Wochenschr., 1885, Nr. 7.
SPINA, Casopis lekaru ceskych, 1885, Nr. 4.
OBRZUT, Prof. Spina's neue Farbungsmethode der Faulnissmikro-

organismen uiid ihre Beziehung zu den Tuberkelbacillen.

Deutsche med. Woch., 1885, Nr. 12.

LEPROSY.

NEISSER, Breslauer arztl. Zeitschr., 1879.

— , Jahresber. d. schles. Ges. fur vaterl. Cultur., 1879.

— , Yirchow's Archiv, 1881, Bd. 84.
KOBNER, Virchow's .Arch., 1882.

HANSEN, Armauer, Yirchow's Arch., Bd. 79. — Ibid., Bd. 90.
CORNIL ET SUCHARD, Ann. de dermat. et syph. Paris, 1881.
GAUCHER ET HILLAIRET, Progres med. Paris, 1880, T. 8. Societe

de biolog., 1881.

JOHN HILLS, On leprosy in British Guiana. London, 1881.
KAPOSI, Wiener med. Wochenschr., 1883.
HILLIS, Trans. Path. Soc. London, 1883, Yol. 34.
BABES, Etude comparative des bacteries de la lepre et de la tuber-.

culose. Compt. rend., 1883, T. 96.
YIDAL, La lepre et son traitement. Paris, 1884.
ARNING, Ueber das Yorkommen der bacillus leprae bei, Lepra
anaesthetica s. nervorum. Yirchow's Archiv, Bd. 97.

LITERATURE.

HOLLER, Deutsches Archiv f. klin. Med., Bd. 34, 1884.

DAMSCH, Uebertragungsversuche von Lepra auf Thiere. Yirch.

Arch., Bd. 92, 1883.

— , Centralbl. f. d. med. Wissensch., Bd. 21, 1883.
KOBNER, Uebertragungsversuche von Lepra auf Thiere. Vir->

chow's Arch., 1882.
CAMPANA, Sur la transmissibilite de la lepre aux animaux. Arch.

ital. de biolog., T. 5. fasc. 2.
Vossrus. Uebertragungsversuche von Lepra auf Kaninchen. Ber;

iiber d. Ophtalmologencongress in Heidelberg, 1881.
VTRCHOW, Berl. klin. Wochenschr., 1885, Nr. 12.
UNNA, Ueber. Lcprabacillen. Deutsche med. Wochenschr., 1885,

Nr. 32.

GLANDERS.

LOFFLBR u. SCHUTZ, Ueber den Rotzpilz. Deutsche med. Wochen-
schr., 1882, Nr. 52.

ISRAEL, Berl. klin. Wochenschr., 1883, Nr. 11.
BOUCHARD, CAPITAN ET CHARRIN, Bull de 1'Acad d. sc. 1882, Nr.

51 (27 Decbr.).

WASSILIEFF, Deutsche med. Wochenschr., 1883, Nr. 11.
MOLKENTIN, Zur Sicherstellung der Diagnose von Rotz. Inaug.-

Diss. Dorpat, 1883.
GRUNWALD, Zur Differentialdiagnose des Rotzes. Oesterr. Mona-

tsschr. fiir Thierheilk, 1884, Nr. 4.
WEICH.SKLBAUM, Zur Aetiologie der Rotzkrankheit des Menschen.

Wiener med. Wochenschr., 1885, 21—24.
FROHNKR, Rotzige Elephantiasis des Kopfes beim Pferde. Rep. d.

Thierheilk, 1883-4.
KITT, Versuche iiber d. Ziichtung des Rotzpilzes. Jahresber d.

Miinchen Thier-arzneisch., 1883-84.

ANTHRAX.

(Ccantpare also p. 53, "Immunity and Protective Inoculation")

POLLENDER, Vierteljahrsclir. f. ger. Med., Bd. 8, 1855.
BRAUELL, Virchow's Arch., Bd. 11, 1857.— Ibid., Bd. 14, 1858.
DAVAINE, Compt. rend Acad. de sc. Paris, T. 57, 1863. — Ibid.,
T. 59, 1863 ; T. 60, 1865 ; T. 61, 1866; T. 77, 1873.
— , Rec. de med. vet., T. 4, 1877.

— , Compt. rend. 1877 (Review of Davaine's Publications in
Cornil et Babes' Handbuch, p. 493).

26 LITERATURE.

PASTEUR, Bull. A cad. de med. Paris, 1877, 1879, 1880 (Earth
Worms).

— , Compt. rend. Acad. de sc. Paris, T. 84, 1877; T. 90, 1880;
Ibid., T. 91, 1880; T. 92, 1881 ; Ibid., T. 95, 1882.
COLIN, Bull. Acad. de mc'd. Paris, T. 2, 1873 ; Ibid., T. 7, 1878.

Ibid., T. 8, 1879 ; Ibid., T. 9, 1880; Ibid., T. 10, 1881.
FELTZ, Sur la role des vers de terre dans la propagation du

charbon. Compt. rend., 1882, T. 95.
BERT, Compt, rend. Soc. de biol., T. 4, 1877; Ibid., T. 5, 1878;

Ibid., T. 6, 1879.

BOLLINGER, v. Ziemssen's Handbuch der spec. Pathol. n. Therapie.
Bd. III.

— , Centralbl. f. d. med. Wissensch., 1872, Bd. 10.
TOUSSAINT, Reclierclies experimentales sur la maladie charbonneuse.
Paris, 1879.

— , Compt. rend. Acad. de sc., T. 85, 1877, 1878, 1880.
CHAUVEAU, Compt. rend. Acad. de sc., T. 90, 1880; T. 91, 1880;

T. 92, 1881 ; T. 94, 1882; T. 96, 1883.
BOULEY, Bull. Acad. de Med. Paris, T. 9, 1880; Ibid., T. 10, 1881.

— i Compt. rend. Acad. de sc., T. 92, 1881. Ibid., T. 93, 1881.
KOCH, Beitrag znr Biologic der Pflanzen. Breslaii, 1876, Bd. 2.
Heft 2.

— , Wundinfectionskrankheiten. Leipzig, 1878.
— , Mitth. aus d. Ges.-Amt., Bd. I., 1881.
OEMLER, Archiv f. wissensch. u. pract. Thierheilk., Bd. 4, 1878.

-Ibid., Bd. 5, 1879 ;— Bd. 6, 1880.
SCHMIDT, Milzbrand bei Wildschweincn. Deutsche Zeitsclir. f.

Thiermed. u. vergl. Pathol., 1879.
EWART, Quart. Journ. of Microsc. Sc., April, 1878.
RODET, Compt. rend., T. 94, 1882.
— , Contribution a 1'etude experimentelle du Charboii Bacfceridien.

Lyon, 1881.
WACHENHEIM, Etude experiinentelle sur la septicite et la virulence

du sang charboniieux. Nancy, 1880.
STERNBERG, Am. Monthly Micr. Journ., Vol. 2, 1881.
HUBER, Deutsche med. Wochenschr., Bd. 7, 1881.
GREENFIELD, Proc. Roy. Soc. London, Vol. 30, 1880.
— , Quart. Journ. Micr. Sc. London, Vol. 20, 1879.
KLEIN, On the relation of Pathogenic to Septic Bacteria, as illus-
trated by Anthrax Cultivations. Rep. of the Medical Officer of
the Local Government Board for 1881, ff.

— , On a Morphological Variety of Bacillus Arithracis. Quart.
Journ. Micr. Sc. n. s., Vol. 23/1883.

LITERATURE. 27

FOKKER, Virchow's Archiv, Bd. 88, 1882.
— , Centralbl. f. d. med. Wissensch., Bd. 18, 1880.— Ibid., Bd. 19,

1881.
SEMMER, Centralbl. f. d. med. Wissensch., Bd. 18, 1880.— Ibid., Bd.

22, 1884.

— , Der Milzbrand und das Milzbrandcontagium. Jena, 1882.
ROLOFF, TJeber die Milzbrandimpfung und d. Entwicklung d.

Milzbrandbakterien. Archiv f. wissensch. u. pract. Thier-

lieilk., Bd. 9, 1883.
— , Der Milzbrand. Berlin, 1883.

ARCHANGBLSKI, Centralbl. f. d. med. Wissensch., 1882, 1883.
DOWDESWELL, Rep. Med. Off. Local Gov. Board, 1883.
To UPPER, Die neueren Erfahrungen iiber d. Aetiologie d. Milzbrands.

Jena, 1883.
BUCHNER, Ueber die cxper. Erzeugnng des Milzbrandcontagiums

aus den Heupilzen, Miinchen, 1880.
— , Versuche iiber die Entstehung des Milzbrands durrli

Einathmung. Sitzungsber. d. K.bayer, Akad. d. Wissensch., 1880.
— . Vortrage im arztl. Verein zu Miinchen, 1881.
— , Die Umwandlung der Milzbrandbakterien in unschadliclie

Bakterien. Virchow's Arch., Bd. 91, 1883.
PKA/.MOWSKI, Acad. d. wissensch. in Krakau, 1884 (polish).
— , Biol. Centralbl., Bd. 4, 1884.

SZPILMAX, Zeitschr. f. physiol. Chemie. Strassburg, Bd. 4, 1880.
FUIEDRICH, Zur Aetiologie des Milzbrands. Miinchen. Inaug-Diss.

Leipzig, 1885.
ESSER & SCHUTZ, Zur Casuistik des Milzbrands. Mitth. a. d. K.

preuss. amtl. Yet. Sanitatsbericht, 1882-1883.
BOLLINGER, Zur Aetiologie des Milzbrands. Sitzungsber. d. Gres. f.

Morphol u. Physiol. zu Miinchen, 1885, 10 Febr.
KITT, Ibid., 1885, Febr.
BLEULER, Milzbrand beim Menschen. Correspondenzbl. d. Schwei/.

Aerzte, 1884.
SCHRAKAMP, Zur. Aetiologie des Milzbrandes. Archiv. f. Hygiene,

Bd. 2, 1884.
V. CHELCHOWSKY, Zur Charakteristik des Milzbrandvirus. !)<•!•

Thierarzt, 1884.

TYPHOID FEVER.

KLEBS, Arch. f. exper. Pathol. u Pharmakol., Bd. 12, 13, 15. 1880-

81.
BiRCH-HiRSCHFELD, Unters. zur Pathologic des Typhus abdominalis,

Zeitschr f. Epidemiologie, I., 1874.

28 LITERATURE.

KLEIN, Med. Centralbl., XII., 1874.

SOKOLOFF, Virchow's Archiv, Bd. 66.

FELTZ, Compt. rend., 1877, T. 85.

EPPINGER, Beitr. zur pathol. Anatomic aus d. patholog. Institut.

Prag., 1880.

LETZEEICH, Virchow's Archiv, Bd. 68.
— , Archiv f. exper. Pathol., Bd. 9, 1878; Bd. 10, 1881.
— , Experimeiitelle Untersuchungen iiber die Aetiologie des

Typhus abdominalis. Leipzig, 1883.
WERNICH, Zeitschr. f. klin. Med., Bd. 6, 1882.

FISCHEL, Ueber das Yorkommen von Mikrokokken in einigen
Organen bei Typhus abdominalis. Beitr. zur Pathol. Anat. aus
d. pathol-anat. Last. Prag., 1880.

TIZZONI, Studi. di pat. sperim. sulla gen. d. tifo. Milano, 1880.
RAPPIN, Contrib. a 1'etude des bact., de la bouche, a 1'etat normal

et dans la fievre typhoide. Paris, 1881.
MARAGHANO, Centralbl. f. d. med. Wissensch., Bd. 15, 1882.
BRAUTLECHT, Pathogene Bakterien im Trinkwasser beiEpidemieen.

Virchow's Arch., Bd. 84, 1881.

ALMQUIST, Typho'idfeberus-Bakterie. Stockholm, 1882.
CROOKE, Brit. Med. Journ., Juli, 1882.

BOENS, Acad. roy. de Med. de Belgique. Bull, 1883. 3. Ser., T. 17.
EBERTH, Der Typhus-Bacillus und die intestinelle Infection.
Volkmann, klin. Vortrage, 1883.

— , Arch. f. pathol. Anat., Bd. 81, 1880. -Ibid., Bd. 83, 1881.
MEYER, Unters. iiber den Bacillus des Abdominaltyphus. Inaug.-

Diss. Berlin, 1881.
GAFFKY, Zur Aetiologie des Abdominaltyphus. Mitth. a. d. Ges.-

Amt., Bd. 2, 1884.

COATS, Eberth's Typhoidbacillus. Brit. med. Journ., Marz, 1882.
TAYON, Le microbe de la fievre typhoide de l'homme. Compt.

rend., T. 99, p. 331 ; T. 101, No. 6.

PFEIFFER, Ueber den Nachweis der Typhusbacillen im Darminhalt
u. Stuhlgang. Deutsche med. Wochenschr., 1885, Nr. 29.

RELAPSING FEYER.

OBERMEIER, Yorkommen f einster, eigene Bewegung zeigender Faden
im Blute von Recurrenskranken. Med. Centralbl., 1873. — Berl.
med. Ges., Marz, 1873. Berl. klin. Wochenschr., 1873.

EXCEL, Ueber die Obermeier'schen Recurrensspirillen. Berl. klin.
Woch.,1873.

WEICERT, Deutsche med. Wochenschr., 1876.

LITERATURE. 29

MOCZUTOWSKY, Deutsch. Archiv f. klin. Med., Bd. 24.

BIRCH-HIRSCHFELD, Ibid., Bd. 13, 1874.

LAPTSCHINSKY, Centralbl. f . d. .med. Wissensch., Bd. 13, 1875.

ALBRECHT, St. Petersb. med. Wochenschr., 1879, Nr. 1.

COHN, Deutsche med. Wochenschr., 1879.

HEYDENREICH, Der Parasit des Riickf all typhus. Berlin, 1877.

— , St. Petersb. med. Wochenschr., 1876.
KOCH, Deutsche med. Wochenschr., 1879..
GUTTMANN, Virchow's Arch., 1880.
MUHLHAUSER, Virchow's Arch., Bd. 97, 1884.
v. JAKSCH, Wien. med. Wochenschr., 1884, Juli.

CHOLERA.

KOCH, Ueber die Cholerabakterien. Deutsche med. Wochenschr.,

1884.
VERHANDLUNGEN* der Conferenz zur Erorterung der Cholerafrage.

Berliner klin. Wochenschr., 1884, Nr. 31, ff. Deutsche med.

Wochenschr., 1884, S. 504 ff.— 2. serie : 4. May, 1885, and the

following days. Deutsche med. Wochenschr., 1885, Nr. 19, 20 ;

37a, 38, 39.
VAN ERMENGEM, Recherches sur le microbe du cholera asiatique.

Paris-Bruxelles, 1885.
— , Conclusions pres a la Soc. Beige de Microsp. dans la seance

du 26 Oct., 1884.
— , Note sur Finoculation des produits de culture du bacille-

virgule. Bull de 1'Acad. roy. de med. de Belgique. 3 Ser., XVIII.
GIBIER ET VAN ERMENGEM, Rech. exper. sur le Cholera. Compt. rend.,

T. 101, 1885.
PFEIFFER, Ueber die Cholera in Paris. Deutsche med. Wochenschr.,

1885, Nr. 2.
JOHNE, Einiges iiber die sogen. Choleracurse im K. Ges.-Amt.

Deutsche Zeitschr. f. Thiermed., Bd. XI. — published separately

by Vogel, Leipzig.
BIANCHI, Lancet, Vol. 2, 1884.
MACNAMARA, Brit. Med. Journ., Vol. 1, 1884.
HUNTER, Ibid., Vol. 1, 1884.
CARTER, Lancet, Vol. 2, 1884.
CAMERON, Brit, Med. Journ., Vol. 1, 1884.
STRAUSS, Roux, THUILLIER ET NOCARD, Compt. rend. Soc. de biol.

Paris, T. 4, 1883.
DOYEN, Mikroorganismen in Leber und Niere von Choleraleichen.

Soc. de Biol. de Paris, 13 Dec., 1884.

30

LITERATURE.

BUCHNER, Ueber Cholerabacillen. Miinehn. arztl. Intelligenzb.,

1884, S. 549.

KLEBS, Ueber Cholera asiatica. Basel, 1885.
SCHOTTELIUS, Zuin mikrosk. Nachw. v. Cholerabacillen in Dejec-

tionen. Deutsche med. Wochenschr., 1885, Nr. 14
BOCHEFONTAINE, Exper. pour servir a 1'etude des phenomenes deter-
mines chez I'homme par I'ingestion stomacale du liquide diarr-

he'ique du cholera, Compt. rend., T. 99, p. 845 : and T. 100, p.

1148.

KLEIN, Brit. Med. Journ., Vol. 1, 1885.
— , Lancet, Vol. 2, 1884. Ibid., Vol. 1, 1885.
— , Proc. Roy. Soc. London, Vol. 38, 1885.
FINKLER u. PRIOR, Unters. iiber Cholera nostras, Deut. med.

Woch., 1884, Nr. 36.
— , Ueber den Bacillus der Cholera nostras und seine Cultur.

Naturforscherversammlung Magdeburg, 1881.
— , Ueber die Kommabacillen. Kolnische Zeit. (!), 1884, 11

Novbr.
— , Forschungen iiber Cholerabakterien. Ergiinzungshefte zuiu

Centrabl. f. allg. Gesundheitspflege, Bd. 1, Heft 5 u. 6.
DENEKE, Ueber eine neue den Choleraspirillen iihnliche Spaltpilz-

art. Deutsche med. Wochenschr., Nr. 3, 1885.
MILLER, Kommaformiger Bacillus aus der Mundhohle. Deut. med.

Woch., 1885, Nr. 9.
EMMERICH, Die Cholera in Neapel. Deutsche med. Wochenschr..

Nr. 50, 1884.
FLUGGE, Kritik der Emmerich'schen Untersuclmngen iiber Cholera.

Deutsche med. Wochenschr., Nr. 2, 1885.
CHEYNE, Brit. Med. Journal, 1885.
DRASCHE, Allg. Wien. med. Zeit., 1885.

BRUNETTI, Fatti Considerazioni Conclusioni sul colera Padua, 1885.
NICATI ET RIETSCH, Arch, de phvsiol., 1885. Compt. rend., T. 9i>.

p. 928.

— , Revue d'hygienc, 1885.
— , Revue de medecin, T. 5, 1885.
TRANSACT, of the Royal Medical and Chirurgical Society of

London, March — April, 1885.
VILLIERS, Sur la formation des ptomaines dans le cholera. Compt.

rend., T. 100, p. 91.
PFEIFFER, Der bisherige Verlauf der Cholera in Thiiringen etc.

Corresp. Bl. des allgem. arztl. Ver. in Thiiringen, 1884, Nr. 9.
FERRAN, Sur 1'action pathogene et prophylactique du bacillus-

virgule. Compt. rend., T. 100, p. 959.

LITERATURE. 31

HERICOURT, Sur la nature indifferente des bacilles-virgules. Ibid.,

p. 1027.
VAN ERMENGEM, Die Ferran'schen Impfungen. Deutsche med.

Woohenschr., 1885, Nr. 29. Compare. Bull, de 1'Acad de med.

Seance du 13 Juillet, 1885.

PNEUMONIA.

KUHX, Die Uebertragbarkeit endemischer Piieumonieformen auf

Kaninchen. Berl. klin. Wochenschr., 1881, Nr. 38.
— , Die contagiose Pneumonic. Deutsch. Arch. f. klin. Med.,

1878.

FRIEDLANDER, Virchow's Arch., Bd. 87, 1882.
— Fortschr d. Med., Bd. 1, 1883, S. 715. Ibid., Bd. 2, 1884, 8.

333 u. 652
— , Beste Farbung zur Darstellung der Kapseln der Pneumo-

niekokken. Fortschritt, III., 92.
MATRAY, Wien. med. Pressc, 1883, Nr. 23.
ZIEHL, Ueber das Vorkommen der Pneunioriiekokken im pneumo-

nischen Sputum. Centralbl. f. d. med. Wissensch., 1883, 1884.
JURGENSEN, Berl. klin. Wochenschr., 1884, Bd. 22.
MENDELSSOHN, Zeitschr. f. klin. Med., 1884, Bd. 7.
EMMERICH, Pneumoniekokken in der Zwischendeckenfiillun^.

Archiv f. Hygiene, Bd. 2, Heft 1.
GERMAIN-SEE, Compt. rend. Acad. de sc. Paris, 1884.

— , Des maladies specifiques du poumon. Paris, 1885.
SALVIOLI u. ZASLEIN, Ueber den Micrococcus und die Pathogenese

der crouposen Pneumonie. Centralbl. f. d. med. Wissench.,

1883.

— , Arch, pour les so. med., Bd. 8, 1884.

PLATONOW, Ueber die diagnostische Bedeutung d. Pneumonie-
kokken. Inaug.-Diss. Wiirzburg, 1884.
MAGUIRE, Brit. Med. Journ., Vol. 2, 1884.
GILES, Ibid., Vol. 2, 1883.
TALAMON, Progr. medic., 1883.

AFANASSIEW, Compt. rend. Soc. de biol. Paris, T. 5, 1884.
KORANYI u. BABES, Pester med. chirurg. Presse, 1884.
A. FRANKEL, Verhandl. d. Congr. f. innere. Med., 1884. — Fortschr.

d. Med., 1884, Nov.

BRIEGER, Zeitschr. f. physiol. Chemic., Bd. 8.
KLEIN, Centralbl. f. d. med. Wissensch., 1884.
NAUWERCK, Ueber morbus Brightii bei crouposer Pneumonie.

Beitr. zur pathol. Anat. von Ziegler. Jena, 1884.

82 LITE R AT u KB:

RIBBERT, Zur Farbung d. Pneumoniekokken. Deut. med. Woehen-

schr., 1885, Nr. 9.
DRESCHFELD, Ueber Wander pneumonie n. ihre Beziehung zur

epidemisclien Pnenmonie. Fortschr. d. Med., III., 389, 1885.
SCHOU, Untersucliungen iiber Vaguspneumonie. Fortschr. der

Medicin., Bd. 3, Nr. 15, 1885.

MALARIA.

KLEBS u. TOMMASI-€RUDELI, Arcli. f . exp. PathoL, Bd. 2, 1879.
TOMMASI-.CRUDELI, Der Bacillus Malariae im Erdboden von Seli-

nunte ti. Campobello. Arch. f. exp. PathoL, Bd. 12.
— , La production naturelle de la malaria. Conference faite a

la 8 sess. dn congres intern, med. a Copeiihague, 1884.
— , Die Malaria von Bom. Deutsch von Schuster. Miinchen,

1882.
LAVERAN, Les parasites da sang dans rirnpaluclisine. Compt.

rend., No. 17, 1882.

— , Traite des fievres palustres. Paris, 1884.
RICHARD, Compt. rend., No. 8, 1882.
MARCHAND, Znr Aetiologie der Maleria. Virchow's Archiv, Bd. 88,

1882.

ZIEHL, Deutsch. med Woch., Nr. 48, 1882.
ROSZAHEGYI, Yon der Ursache des Wechselfiebers. Biol. Ctrlbl.,

Bd. 2, 1882.
KOTELMANN, Der Bacillus Malariae im Alterthum. Virchow's

Arch., Bd. 97, 1884.
STERNBERG, Nat. Board of Health. Bull. Suppl., Washington,

1881.

CUBONI UND MARCHTAFAVA, Atti della, R. Acad. dei Lincei., 1881.
- — , Neue Studien lib. d. Natur der Malaria. Arch. f. exp. PathoL.

Bd. 13.
CECI, Ueber die in den malarischen und gewolmlichen Bodenar-

ten enthaltenen Keime und niederen Org'anismen. Arch. f.

exp. PathoL, Bd. 15 u. 16.
MARCHIAFAVA u. CELLI, Neue Untersucliungen iiber die Malariain-

fection. Fortsch. d, Med., III., 339.
— Blutveranderung bei Malaria. Arch. ital. de biologic, Bd. T>,

fasc. 2.

— , Atti della R. Academia dei Lincei, 1884.
v. SEHLBN, Fortschr. d. Med., Bd. II., 1884.
LEONI, Gazetta medica di Roma, 1884, Dec.
GERHARDT, Zeitsclir. f. klin. Med., Bd. 7, 1884.

LITERATURE. 33

MARRIOTMI & CIARROCCHI, Lo sperimentale, Bd. 54, 1884.

TORELLI, La malaria in Italia. Roma, 1883.

MAUREL, L'etiologie et la nature du paludisme. Ann. d'hygieuc,

1883.
BARBELS, Gaz. des hopit., 1882.

EYE AFFECTIONS.

E BERTH, Ueber Entziindung der Hornhaut nach Trigeminus-

Durchsneidung. Med. Centralbl., XI., 1873.
FRISCH, Die Milzbrandbakterien und ihre Vegetationen in d.

lebenden Hornhaut. Acad. d. Wiss., Bd. III., 1876.
SciiMiDT-RiMPLER, Ueber Hornhautimpfungen mit Beriicksichti-

gung eiteriger Keratitis beim Menschen. Marburger Sitzungs-

ber., 1876, III.

LEBER, Ueber Entziindung der Hornhaut durch septisclic Infec-
tion. Med. Centralblatt., XI., 1873.
BALOGH, Sphaerobakterien in der entziindeten Hornhaut. Med.

CentralbL, XIV., 1879.
DOLSCHENKOFF, Impfung faulender Sabstanzen auf die Kaninchen-

hornhaut. Med. CentralbL, ]873.

HORNER, Keratitis mycotica. Monatsbl. f. d. Augenheilk, XIII.
ROTH, Retinitis septica. Virchow's Archiv, Bd. 55.
KAHLER, Ueber septische Retinitis. Prager Zeitschr. f. prakt.

Heilk., Bd. I., 1882.
FORSTER, Pilzmasse im unteren Thranenkanalchen. Arch. f.

Ophthalm., XV., 1.
GRAFE, Ibid., Bd. XV., 1.
COHN, Ibid., Bd. 15.
v. REUSS, Pilzconcretionen i. d. Thranenrohrchen. Wien. med.

Presse, 1884.
GOLDZIEHER, Streptothrix Foersteri im unteren Thranenrohrchen.

Centralblatt f. prakt. Augenheilk, 1884, Febr.
HERZOG VON BAYERN, Zur Kenntniss der beim Menschen vorkom-

menden Bacillen. Ibid., 1880, October.
SATTLER, Unters. iiber das Trachom. Ber. lib. d. Ophthalmologen-

Congress zu Heidelberg, 1882.
KRONER, Zur Aetiologie der Ophthalmoblennorrhoe. Verh. d.

Naturforscher Vers. Magdeburg, 1884 (for the rest of the

literature see under " Gonorrhoea ").
KUSCHBERT u. NEissER, Zur Pathologic und Aetiologie der Xerosis

conjunctivae. Bresl. arztl. Zeitschr., 1883, Nr. 4.
KUSCHBERT, Deutsch. med. Woch., 1884, Nr. 21.

3

34 LITERATURE.

LEBER, Ueber die Xerosis der Bindehaut. v. Graefe's Arch. f.

Ophthalmologie 29, 3.
SCHLE-ICH, Verb, des Ophthalmologen-Congr., zu Heidelberg,

1883.
BOCK, Ueber die miliare Tuberkulose der Uvea. Virchow's

Arch., 1883, Bd. 91.

MICHEL, Graefe's Archiv f. Augenheilkunde, Bd. 1, 1882.
DEUTSCHMANN, Zur Pathogenese der sympathischen Ophthalmic.

v. Graefe's Arch., 30, 2 Abthl.
ABRAHAM, Dublin Journ., 73. Febr., 1882.
DE WECKER, Die Jequirity'sche Ophthalmie. Klin. Monatsbl. f .

Augenheilkunde Jahrg., 20 u. 21.
SATTLER, Ueber d. Natur der Jequirity- Ophthalmie. Zehender's

klin. Monatsblatt, Juni, 1883.
— , Wien. med. Woch., 1883. Nr. 17.

SATTLER ET DE WECKER, L'Ophthalmie jequiritique. Paris, 1883.
CORNIL ET BERLIOZ, Sur rempoisonnement par le Jequirity.

Compt. rend, de I'Acad. d. sc., 1883, Sept,
NEISSER, Fortschr. d. Med., Bd. II., S. 73.
SALOMONSON, Ibid., Bd. II., S. 78.
KLEIN, Centralbl. f. d. med. Wiss., 1884, Nr. 8.
VENNEMANN ET BRUYLANTS, Le jequirity et son principe pathogene.

Bruxelles, 1884.
SATTLER, Ibid., II., S. 501.

Yossius, Berl. klin. Wochenschr., 1884, Nr. 17.
DE WECKER, v. Graefe's Arch., Bd. 30, Abth. 1.

— , Archiv. f. Augenheilkunde., Bd. 14.
KNAPP, Klinische Beob. iiber die Anweiidung von Jequirity bei

Trachom. Arch. f. Augenheilk., XIV.

OTHER INFECTIVE DISEASES OF MAN.

VARIOLA, VACCINIA.

KEBER, Virchow's Arch., Bd. 42.

CHAUVEAU, Compt. rendus., 1868, Februar.

COHN, Virchow's Archiv, Bd. 55, 1872.

LUGINBUHL, Der Micrococcus der Variola. Verhdl. d. phys.-med.

Ges. in Wiirzburg, 1873.
ZULZER, Berl. klin. Wochenschr., 1872.
WEIGERT, Anat. Beitr. z. Lehre v. d. Pocken., 1874.
PISSIN, Berl. klin. Wochenschr., 1874.

KLEBS, Arch. f. exp. Path. u. Pharmakol. Leipzig, Bd. 10, 1878.
PoiiL-PiNCUR, Vaccination. Berlin, 1882.

LITERATURE. 35

TAPPE, Aetiologie u. Histologie der Schafpocken. Berlin, 1881.
PLAUT, Das organis. Contagium der Schafpocken. Leipzig, 1883.
CORNIL ET BABES, Soc. medicale des hopitaux, 1883, 10 August.
QUIST, St. Petersburg medic. Woch., 1883, Nr. 46.
FURST, Corresp.-Blatt. d. arztl. Kreis- u. Bez.-Vereins. in Sachsen.

Leipzig, Bd. 33.

HAMERIXK, Ueber die sog. Vaccination u. 'Variola. Prag., 1884.
PFEIFFER, Ueber die Riickimpfung auf Kiihe und Kalber. Jahrb.

f. Kinderheilk, 1882, Bd. 19.
— , Ueber Sprosspilze in der KUlberlymphe.
M. WOLF, Zur Impffrage. Berl. klin. Wochensch'r., 1883, Nr. 4.

SCARLATINA.

COZE ET FELTZ, Les Maladies infectieuses, 1872.
POHL-PIXCUS, Centralbl. f. d. med. Wiss., 1883.
HEUBNER LT. BAHRDT, Zur Kenntniss der Gelenkeiterungen bei

Scharlach. Berl. klin. Woch., 1884, Nr. 44.
CROOKE, The Lancet, 1883, March.
ROTH, Miinchener arztl. Intelligenzbl., 1883.
J^OKAI, Orvosi hetilap. 1882 u. 1885. (Arthritis scarlatinosa ; s.

Cornil u. Babes' Handbuch, S. 537.)

YELLOW FEVER.

DOMINGO* FREIRE, Recherches sur la cause, <tc., de la fievre jauiie.

Rio de Janeiro, 1884.
DOMINGOS FREIRE ET REBOURGEOX, Compt. rend., T. 99, p. 804.

1884.
BABES, Sur les microbes trouves dans le foie et dans le rein

d'individus morts de la fievre jaune. Compt. rend. 1883. 17

Sept.
BOULEY, L'inoculation preventive de la fievre jaune. Compt.

rend., Bd. 100, p. 1276.

CEREBROSPINAL-MENINGITIS.

LEYDEN, Die Mikrokokken der Cerebrospinal-Meningitis. Cen-
tralbl. f. klin. Med., 1883, Nr. 10.
LEICHTENSTERN, Deutsche Medic. Woch., 1885, Nr. 23 u. 31.

INFLUENZA.

SEIFERT, Uel:er Influenza. Volkmann's Sammlung klin. Vortrage,
Nr. 240.

36 LITERATURE.

ACUTE YELLOW ATROPHY OF THE LIVER.

EPPINGER, Prag. Viertelj., 1875.
HLAVA, Prag. med. Wochenschr., 1882.

HEMOPHILIA NEONATORUM.

KLEBS u. EPPINGER, In Klebs' Beitr. zur pathologischen Anat., 1878.

RABIES.

COLIN, Bull. Acad. de med. Paris, T. 10, 1881.
DOLE"RIS, Gaz. med. de Paris, T. 3, 1881.

— , Tribune med. Paris, T. 14, 1881.
PASTEUR, Compt. rend. Acad. de sc., 1881 — 83.

— , Nouvelle communication sur la rage. Ann. de med. veterin,

1884, Part 5.
PASTEUR, CHAMBERLAND, Roux ET THUILLER, Nouveaux faits pour

servir a la connaissance de la rage. Compt. rend., 1882, T. 95.
BERT, Contribution a 1'etude de la rage. Compt. rend., 1882.
GIBIER, Ibid., T. 96, 1883.

RHINOSCLEROMA.

CORNIL, B. de la soc. anatom., 1885, 15 Febr.

CORNIL ET ALVAREZ, Sur les micro-organismes du Rhinosclerome.
Acad. de Med., 1885, March.

OZAENA.

E. FRANKEL, Virchow's Arch., Bd. 90, 1882.
LOWENBERG, Deutsche med. Woch., 1855, Nr. 1.

LUNG AFFECTIONS (Pneumonia, see p. 31).

JAFFE u. LEYDEN, Ueber Organismen bei Lungengangriin (Lepto-

thrix). Med. Centralzeitung 1866. Deutscli. Arch. f. klin.

Med., II.

TRAUBE, Leptothrix im Sputum. Deutsche Klinik., 1853.
HEIMER, Ueber Pneumonomycosis sarcinica. Deutches Arch. f.

klin. Med., 1877 (vgl. Sarcina, S. 29).
BURGER, Der Keuchhustenpilz. Berl. klin. Wochenschr., 1883,

Nr. 1.

GOITRE.

KLEBS, Studien iiber Kretinismus. Prag, 1877.
BIRCHER, Der endemische Kropf. Basel, 1883.

LITERATURE. 37

SKIN AFFECTIONS.

RINDFLEISCH, Mycosis fungoides. Deutsche med. Woch., 1885.
AUSPITZ, Granuloma fungoides. Viertlj. f. Dermat. u. Syph.,

1885.
v. SEHLEN, Mikrokokken bei Area Celsi. Fortschr. de Med., Bd. 1,

1883.— Virch. Arch., Bd. 99, S. 327.— Bd. 100, S. 361.
MICHELSON, Ibid., Bd. 99, S. 572.— Bd. 100, S. 576.
THIN, British Medic. Journ., 1882, S. 304.

DISEASES OF THE MOUTH AND TEETH.

(As to Leptothrix see also p. 24, Furster, ff., 8. 26, Jaffe u. Ley den ff ;
as to Thrush, *., 8. 9.)

LEBER, Berl. klin. Wochenschr., 1867, Nr. 16.

LEBER u. ROTTENSTEIN, Unters. iiber Caries der Zahne. Berlin, 1867.

SATTERTHWAITE AND CURTIS, Rep. of the New York Board of Health,

1877.
MILLER, Der Einfluss der Mikro-organismen auf die Caries der

Zahne. Arch. f. exp. Path., XVI., 1882.

— , Deutsche med. Woch., 1884, Nr. 25 u. 36.

— , Correspdzbl. f. Zahnarzte., Bd. 13, 1884.

— , Ueber einen Zahnspaltpilz Leptothrix gigantea. Ber de

deutsch. bot. Ges., 1883, Heft 5.

v. UBISCH, Leptothrixbildung im Munde. Berl. klin. Wochen-
schr., 1875, Nr. 52.
ARNDT, Beob. an Spirochaeta denticola. Arch. f. pathol. Anat.,

Physiol. u. klin. Med., 1880, Bd. 79.
PASTEUR, Bull, de 1'Ac. de med., 1881, Januar.
RAYNAUD ET LANNELONGUE, Bull, de 1'Acad. de med., 1881, Febr.
VULPIAN, Ibid., 1881, Marz.
KUHN, Berl. klin. Woch., 1881.

A. FRANKEL, Deutsche med. Wochenschr., 1884, Nr. 25.
RAPPIN, Des bacteries de bouche a 1'etat normale et dans la fievre

typho'ide. Paris, 1881.
RASMUSSEN, Om Drykning af Microorganismer fra spyt of sunde

mennesker. Kopenhagen, 1883.
KLEIN, Centralbl. f. d. med. Wiss., 1884, Nr. 30.
LOFFLER, Mittheilungen aus dem kais. Ges.-Amt., Bd. II., S.

449 u. 480.
ROSENBACH, Microorganismen dei den Wundinfectionskrankheiten.

Wiesbaden, 1884, S. 77 (Zahncaries).

38 LITERATURE.

DISEASES OF ANIMALS.

GENERAL LITERATURE.

ROLL, Die Thierseuchen. Wien, 1881.

ZURN, Parasiten in und auf dem Korper der Haussaugethiere, 1874.
PUTZ, Die Seuchen- nnd Herdekrankheiten der Hausthiere.
Stuttgart, 1882.

HYDROPHOBIA, see p. 36.

RAUSCHBRAND.
(Symptomatic Anthrax, Black leg. &c.)

BOLLINGER u. FESER, Wochenschr. f. Thierheilkunde., 1878.
ARLOING, COBNEYIN ET THOMAS, Compt. rend, de 1'Acad de sc.

1880—83.

— , Revne de med., 1881, 1883, 1884.
— , Du charbon bacterien. Paris, 1883.
— , Bull, de 1'Acad. de Med., 1881.
BABES, Journ. de 1'anatomie, 1884, Janvier.
NEELSEN u. EHLERS, Ueber den Rauschbrand. Ber. d. Naturforsch.

Ges. zu Rostock., Jannar, 1884.
EHLERS, Unters. iib. d. Ranschbrandpilz. Iiiaug.-Diss. Rostock,

1884.

KITT, Unters. iiber malignes Oedem und. Rauschbrand bei Haus-
thieren. Jahresber der K. Thierarzneisch. in Mlinchen, 1883-84.

RINDERPEST.

SEMMER u. ARCHANGELSKI, Ueber das Rinderpestcontagium uud
dessen Mitigation. Centralbl. f. d. med. Wiss., 1883.

SEMMER, Rinderpestahnliche Erkrankungen nnd die Mikro-
organismen bei denselben. Dentsche Zeitschr. f. Thiermed. XI.,

S. 77.

PLEURO-PNE UMONI A.

SUSSDORPF, Ueber d. Lnngensenche des Rindes. Deutsche Zeitschr.

f. Thiermed. u. vergl. Pathol., 1879.
MAYRWIESER, Ueber infectiosen Bronchialcroup bei Bindem.

Wochenschr. f. Thierheilk n. Viehzucht., 1884, 19.
PASTEUR, Note snr la peripneiimonie contagieuse des betes a

cornes. Recueil de med. vet., 1882.

CORNIL ET BABES, Arch, de physiol. norm, et path., 1883, T. 2.
POLS u. NOLEN, Centralbl. f. d. medic. Wissensch., 1884, Nr. 9.

LITERATURE. 39

SWINE ERYSIPELAS.

PASTEUR, Sur le rouget, ou mal rouge des pores. Compt. rend.,

T. 95, 1882.

CORNIL ET BABES, Arch, de physiol., 1883, August.
KLEIN, Rep. of the Med. Offic. of the Privy Council, 1877-78.
— , Die Bakterien der Schweineseuche. Virchow's Archiv, Bd.

95.

EGGELING, Reference in Fortschr. d. Med. I., 793.
PASTEUR ET THUILLIER, Bull, de 1'Acad. de med. de Paris, 1883.

Compt. rend., Bd. 97, 1883.
LOFFLER, Experimentelle Untersuchungen iiber Schweinerothlauf.

Arbeiten aus dem kaiserl. Gesundheitsamt, Bd. 1, 1885.
SCHUTZ, Ueber den Rothlauf der Schweine und die Impfung des-

selben. Ibid., S. 56.
LTDTIN u. SCHOTTELIUS, Der Rothlauf der Schweine. Wiesbaden,

1885.

CHICKEN CHOLERA.

ZiJRN, Die Krankheiten des Hausgefliigels. Weimar, 1882.

ME"GNIN, Maladies des oiseaux.

IOANNES ET M^GNiN, Journ. d'acclimatation, 1877.

SEMMER, Hulmerpest. Deutsche Zeitschr. f. Thiermed. u. vergl.

Path., 1878.

PASTEUR, Sur la cholera des poules. Compt. rend., T. 90, 1880.
— , Hiihnercholera. Uebersetzt von A. Schuster. Arch. f. exp.

Pathol., Bd. 12.
PERRONCITO, Ueber das epizootische Typhoid der Huhner. Arch.

f. wiss. u. prakt. Thierheilk, 1879.
CORNIL, Arch, de physiol., 1882, Bd. 10.
BABES, Compt. rend, de 1'Acad. d. sc., 1883, Sept.

- Arch, de physiol., 1883, Juli.
KITT, Mittheilungen iiber die Typhoidseuche des Gefliigels. Allg.

deutsche Gefliigel-zeitung, 1885, 15 Febr.
PETRI, Centralbl. f. d. med. Wissensch., 1884.
BARTHE"LE"HY, De I'mcubation des oeufs d'une poule atteinte du

cholera des poules. Compt, rend., 1883, T. 96, No. 18.

DISEASE OF PARROTS.

EBERTH, Virchow's Archiv, Bd. 80.
WOLFF, Ibid., Bd. 92, 1883.

40 LITERATURE.

DISEASE OP SILKWORMS. — PEBRINE.

CORNALIA, Bapp. della Comissione per le studio della mallattia dei

briochi. Milano, 1877.
— , Ueber Pebrine. Monographia del Bombice del Gelso.

Milano, 1856.
LEBERT, Verein zur Befb'rderung d. Seidenbaues d. Prov. Bran-

denb., 1856-57.
FREY u. LEBERT, Ueber Panhistophyton. Vierteljahrschr. d. natur-

wissensch. Ges. -Zurich, 1856.

OSIMO & VITTADINI, Giorn. Instit. Lombard, Bd. 3.
— , Becherches sur les maladies des vers a soie. Padua, 1859.
NAGELI, Ueber Nosema bombycis. Bot. Zeitg., 1857.
PASTEUR, Etudes sur les maladies des vers a soie. Paris, 1870.

FLACHERIE.

LEYDIG, Ueber Gattine. Du Bois-Beymond's u. Beichert's Archiv,

1863.
BiscHAMP, Ueber Micrococcus bombycis. Compt. rend., 1867, Bd.

64.

PASTEUR, Ibid., Bd. 64.
VERSON ET VLACOVITSCH, Becherches sur la gattine et la flacherie.

Publ. de la station sericicole de Montpellier, 1874.
FERRY DE LA BILLONE, Compt. rend, du congres internat. sericicole,

1878.

SAPBOPHYTES.

(See also References in the Text.)
BACTERIA WHICH PRODUCE PIGMENT.

EHRENBERG. Micr. prodigiosus. Yerhandl. d. Berl. Acad., 1839.
SCHROTER, Ueber einige von Bakterien gebildete Pigmente.

Cohn, Beitr. z. Biol. der Pflanzen, Bd. L, Heft 2.
ERDMANN, Bildung von Anilinfarben aus Proteinkorpern. Journ.

f. pract. Chemie., Bd. 99, 1866.
LANKESTER, On a Peach-coloured Bacterium. Quart. Journ. of

micr. sc., Vol. 13, 1873 ; Ibid., Vol. 16, 1876.
— , An experiment on the destructive effect of heat upon life of

Bacteria and their germs. Nature, 1874, IX.
KLEIN, Quart. Journ. of micr. sc., Vol. 15, 1875.
WERNICH, Cohn's Beitrage zur Biol. d. Pflanzen, III., Heft 1.
GIARD, Bevue des sc., T. 5, 1877.
FRANK (Bacillus ruber), Cohn's Beitr. z. Biol. d. Pflanzen, Bd. L,

Heft 3.

LITERATURE. 41

COHN u. MIFLET (Bact. erythrosporus), Ibid., Bd. III., Heft 1.

VAN TIEGHEM, Bull, de la Soc. bot. de France, 1880.

LUCKE, Arch. f. klin. Chir., 1862 (blue pus).

GIRARD, Unters. iiber blauen Eiter. Chirurg. Centralbl. II., 1875.

E BERTH, Centralbl. f. d. med. Wissensch., 1863 (Idem).

— , Yirchow's Archiv, Bd. 72, 1875 (Idem).
FORDOS, Compt. rend, de 1'Acad. de sc., T. 51 (Idem).
GESSARD, De la pyocyanine et de son microbe. These de Paris,

1882.
CHARRIN, Communication faite a la Societe anatomique, 1884,

December (Blauer Eiter).
BABES, Vom rothen Schweiss. Biolog. Centralbl., Bd. 2, 1882.

PHOSPHORESCENCE.

BANCEL ET HUSSON, Sur la phosphorescence de la viande dehomard.

Compt. rend., 1879, T. 88.
NUESCH, Ueber das leuchtende Fleisch gestorbener Thiere.

Cosmos les Mondes, Revue hebdom. des sciences, 1878.
LASSAR, Pfliiger's Archiv, Bd. 21, 1880.
LUDWIG, Micrococcus Pfliigeri. Hedwigia, 1884, Nr. 3.
— , Ueber die spectroscopische Untersuchung pathog. Pilze.

Zeitschr. f. Mikrosk., Bd. 1, 1884.

SARCINA.

GOODSIR, Edinb. Med. and Surg. Journ., 1842.

OERSTED, Naturhist. Tidsskrift., Bd. III., 1840.

WELCKER, Ueber Sarcina. Henle's Zeitschr. f. ration. Med., 3

Ser., Bd. 5.

E BERTH, Virchow's Archiv, 1858, Bd. 13.
COHN, Beitr. z. Biol. d. Pflanzen, Bd. 1, Heft 2.
ITZIGSOHN, Virchow's Archiv, Bd. 13.
CASPARY, Schriften der physik. okon. Ges. zu. Konigsberg, Bd. 15,

1874.

VIRCHOW u. COHNHEIM, Virchow's Arch., Bd. 10 u. 33.
SURINGAR, Arch. Neerland, 1866.

— , Ueber den Zellenbau der Sarcina. Bot. Zeit., 1866.
HELLER, Heller's Arch. f. Chemie., 1847 (Harnsarcine).
WELCKER, Zeitschr. f. ration Med., 1859 (Idem).
MUNK, Virch. Arch., Bd. 22, 1861.— Med. Centralbl., 1864 (Idem).
PASTEUR, Ann. de chim. et de phys., T. 6i, 1862.
LOSDORFER, Med. Jahrb,, 1871, Heft 3.

k> LITERATURE!.

FRIEDREICH, Beitrage zur Kenntniss der Sputa. Virch. Arcli., Bd.

30.
HEIMER, Ueber Pneumonomycosis sarcinica. Deutsch Arch. f. klin.

Med., 1877.
FALKKNHEIM, Arch. f. exp. Patholog. u. Pharmakol, Bd. 19.

OTHER SAPROPHYTES.

LtJDERS, Ueber Abstammung u. Entwicklung des Bacterium termo.

Bonn, 1867.

EVVART, Proceedings of the Roy. Soc. of London, 1874.
DALLINGER, Journ. of the Roy. Microscop. Soc., London, 1878.
DALLINGER AND DRYSDALE, The Monthly Microsc. Journ., 1875.
EIDAM, Cohn's Beitr. zur Biol. d. Pflanzen, Bd. 1, Heft 3.
VAX TIEGHEM, Sur les pretendus cils des bacteries. Bull, de la

Soc. bot, de France, 1879.
KXGELMANN, Bacterium photometricum. Unters. aus d. phys. Laborat.

7.n Utrecht, 1882.— Pfliiger's Arch. f. d. ges. Physiol., Bd. 30,

S. 95, 1882.
KURTH, Bacterium Zopfi. Ber. d. deutsch. bot. Ges. Botanische

Zeitg., 1883.
ZOPF, Bacterium merismopedioides. Sitz.-Ber. d. Botan. ver. d.

Prov. Brandenb., Juni., 1882.
BREFELD, Bacillus subtilis. Ges. nat. Freunde, Berlin, 1878, u. in

Schimmelpilze, Heft 4.
VANDEVELDE, Studien zur Chemie des Bacillus subtilis. Zeitschr. f .

phys. Chemie, Bd. 8, 1884.

As to Leptothrix s., pp. 24, 37, 53.
GEDDES AND EWART, On the Life-History of Spirillum. Proceed.

of the Roy. Soc. of London, 1878.

MUIILHAUSER, Ueber Spirillen. Virch. Arch., Bd. 97, 1884.
KUTZING, Sphaerotilus natans. Linnaea 8, 1883.
EIDAM, Schles. Ges. f. vaterl. Cultur., 1876.
WEISSE, Monas Okenii. Bull, phys.-mathemat. de St. Petersbourg,

III., 1845.
COHN, Ueber d. Brunnenfaden. Beitr. z. Biol. d. Pflanzen, Bd. I.,

Heft 1.

ZOPF, Ueber Crenothrix polyspora. Berlin, 1879.
LANKESTER, Quarterly Journal of Microscop. Sc., 1873 and 1876.
ENGLER, Pilzvegetat. des weissen oder todten Grundes in der Kieler

Bucht. Ber. d. Comm. zur Erforschung deutscher Meere,

1881.
BILLET, Sur la formation des spores chcz le Cladothrix dicho-

toma. Compt. rend., T. 100, p. 1251.

LITERATURE.

43

GIARD, Sur le Crenothrix Kuhniana. Compt. rend., 1882.
ZOPP, Zur Morphologic der Spaltpflanzen. Leipzig, 1882.
COHN, Ueber zwei neue Beggiatoen. Hedwigia, 1865, p. 81 — 83.
CIENKOWSKI, Zur Morphologic der Bakterien. St. Petersburg, 1876.
BICHTER, Ibid., 1884.

BIOLOGY OF THE BACTERIA.

GENERAL.

COHN, Beitr. z. Biol. d. Pflanzen. Breslau, 1875, and following years.
NAGELI, Die niederen Pilze. Miinchen, 1877.

— , Unters. iiber niedere Pilze. Miinchen, 1882.
NEXCKI, Beitr. z. Biologic d. Spaltpilze. Jonrn. f. prakfc. Chemie.,

N. F., Bd. 19, 20, 23.
— , Virchow's Archiv, 1879.
WIESNEB, Sitz.-Ber. d. Kaiserl. Akad. d. Wissensch. zu Wien. I.

Abthlg., 1873, April.
EIIUM, Cohn's Beitr. zur. Biol. d. Pflanzen, Bd. I., Heft 3.

ANALYSES.

RAULIN, Compt. rend., T. 56.
GAYON, Bull, de la Soc. Chim., T. 35.
SIEBER, Journ. f. prakt. Chemie. (2) 23, p. 412.
NAGELI, Sitz.-Ber. d. K. bayer. Akad. d. Wissensch., 1878, Mai.
MARTIN u. Low, Journ. f. prakt. Chemie., Bd. 17.
NENCKI, Beitrage zur Biol. der Spaltpilze. Leipzig, 1880.
— , Ueber das Eiweiss der Milzbrandbacillen. Ber d. deutschen
chem. Gesellsch., 1884, p. 2605.

NUTRIENT MATERIALS.

RAULIN, Compt. rend., T. 56.

BUCHHOLTZ, Arch. f. exp. Pathol., Bd. 7.

MAYER u. KNIERIM, Landwirthsch. Versuchsstat., Bd. 16.

COHN, 1. c.

NAGELI, Untersuchungen iiber niedere Pilze. Miinchen, 1882.

v. JAKSCH, Zeitschr. f. physiol. Chemie., Bd. 5, 1881.

See under Fermentation, page 45 ; Pasteur, Duclaux, Schiitzen-

be»ger, Mayer, Nageli.

(Nutrient Materials of Yeast.)

INFLUENCE OF OXYGEN.

PASTEUR, Compt. rend. 52, p. 340, 1260, T. 56.— T, 75.— T. 80,
LIEBIG, Annal. d. Chem. u. Pharm., 1870, T. 153.

44 LITERATURE.

SCHUTZENBERGER ET QUINQUAUD, Compt. rend., T. 77.

A. MAYER, Landwirthsch. versuchsstat., 1873, Bd. 16.— Ibid., 1880,

Bd. 25.

— , Poggendorf's Annalen., 1871.

— , Zeitschr. f. Biol., Bd. 5.
MUNTZ, Ann. de Chim. et de Phys., 1876, Bd. 8.
BREFELD, Landwirthsch. Jahrber., 1874, Bd. 3.— Ibid., 1876, Bd. 5.

— , Verhandl. d. Wiirzburger physik.-med. Ges., 1873.
HUFNER, Journ. f. prakt. Chemie., 1876, Bd. 13.
PASCHUTIN, Virchow's Arch., Bd. 59.

GROSSMANN u. MAYERHAUSEN, Archiv f. phys., 1877, Bd. 15.
GUNNING, Chem. Centralbl., 1878, P. 799.— 1880, P. 9.— Ibid., 20,

P. 418.

TRAUBE, Ber d. chem. Ges. 1874, P. 875.
NENCKI, Beitrage z. Biologic d. Spaltpilze., 1880.
— , Journ. f. prakt. Chemie., 19, P. 337.
— , Ueber die Zersetzung der Gelatine. Bern, 1876.
LECHARTIER ET BELLAMY, De la fermentation des fruits. Compt.

rend., T. 69, 75, 79, 81.

POPOFF, Pfliiger's Arch. f. Physiol., 10, P. 135.
JEANNERET, Journ. f. prakt. Chemie., N.F. 15, P. 353.
HOPPE-SEYLER, Ueber d. Einfluss des Sauerstoffs auf Garungen.

Strassburg, 1881.
— , Die Einwirkung von Sauerstoff auf die Lebensthatigkeit-

niederer Organismen. Zeitschr. f. phys. Chemie., Bd. 8, 1884.
GROSSMANN u. MAYERHAUSEN, Das Leben der Bakterien in Gasen.

Pfliiger's Arch., Bd. 15.
SI'ILMANN, Verh. d. Milzbrandbacillen in Gasen. Zeitschr. f. physiol.

Chemie., Bd. 4.
PAUMES, Rech. sur la respiration de la lecure. Ref. Fortschr. d.

Med., Bd. 2, p. 53.

INFLUENCE OF LIGHT, ELECTRICITY AND ATMOSPHERIC PRESSURE.
ENGELMANN, Botan. Zeitg.,1882. — Arch. f.d. ges. Physiologic, Bd. 26.
JAMIESON, Transact, of the Roy. Soc. of Victoria, Vol. 20.
STRASBURGER, Wirkung des Lichts und der Warme auf. Schwarm-

sporen, 1878.

DOWNES AND BLUNT, Ibid., Bd. 20. *

COHN u. MENDELSOHN, Ueber Einwirkung des elektrischen Stromes

auf die vermehrung d. Bakterien. Beitr. z. Biol. d. Pflanzen.,

Bd. III., Heft 1.
DUCLAUX, Influence de la lumiere du soleil sur la vitalite des

germes de microbes. Compt. rend., Nr. 2, 1885.

LITERATURE. 45

CORTES, De Faction des hautes pressions sur les phenomenes de
la putrefraction, etc. Compt. rend., T. 99, p. 385.

REGNARD, Rech. sur 1'influence de tres hautes pressions sur les
org. vivants. Compt. rend., T. 98, p. 744.

INFLUENCE OF MOVEMENT.

HORVATH, Arch. f. d. ges. Physiol., Bd. 17.

REINKE, Ibid., Bd. 23.

TUMAS, St. Petersb. med. Wochenschr., 1881.

FERMENTATION.

(For Yeast, seep. 8.)

FERMENTATION IN GENERAL AND THE ALCOHOLIC FERMENTATION.

BRACONNOT, Ann. de Chim. et Phys., T. 47, 59.
SCHUBERT, Poggendorf's Annalen., Bd. 69 u. 77.
BERZELIUS, Lehrbuch der Chemie, Bd. 8, P. 84.
— , Jahresberichte, 1839, 1840.
SCHONBEIN, Journ. f. prakt, Chemie, Bd. 63, P. 323.— Bd. 89,

P. 323.
— , Verhandl. d. Baseler naturf. Ges., [Bd. 4, P. 797.— Bd. 5,

P. 1—5.

— , Zeitschr. f . Biol., Bd. 1, P. 273.— Bd. 3, P. 140.— Bd. 4, P. 367.
MITSCHERLICH, Monatsber d. Berl. Akad. d. Wiss., Dec., 1841.
— , Poggendorf's Annalen., 1842, Bd. 55.— Ibid., 1843, Bd. 59.
LIEBIG, Yerhandl. der Miinchener. Akad. d. Wiss. 9 Mai, 1861 u.

5 Nov., 1869.

— , Annalen der Pharmacie, Bd. 30, P. 250.

— , Die Chemie in ihrer Anwendung auf Agricultur u. Physio-
logic. Braunschweig, 1846, P. 374—584.
— , Ueber Gahrung, Quelle der Muskelkraft und Ernahrung.

Leipzig u. Heidelberg, 1870.
PASTEUR, Etudes sur le vin., 1866.
— , Etudes sur la biere, 1876.
— , Annal. de chim. et de phys., 1860, III. sir., T. 58, Ibid., T.

64, 1862.

— , Compt. rend., 1857, T. 45— Ibid., 1861, T. 52.— Ibid., 1863,
T. 56.— Ibid., 1864, Jan.— Ibid., 1871, Dec.— Tbid., 1872, T.
75 ff.

TRAUBE, Chem. Ber., 8, P. 776.
— , Poggendorf's Annalen., 1858, Bd. 103, P. 331.
— , Theorie der Ferment wirkungen. Berlin, 1858.

46 LITERATURE..

DUMAS, Compt. rend., 1872, T. 75, Nr. 6.

— , Ann. de chim. et de phys., 1874.
HELMHOLTZ, Miiller's Archiv, 1843, P. 453.

— , Journal f. prakt Chemie, Bd. 31, P. 429.
TURPIN, Compt. rend., T. 7, 1838.

— , Annal. d. Chemie u-. Pharmacie, 1839, T. 23, P. 100.
LUDERSDORFF, Poggendorf s Annalen, Bd. 67, P. 408.
C. SCHMIDT, Annal. d. Chemie und Pharm., T. 61, P. 168.
BLONDEAU, Journ. de Pharm., 1846, T. 12, Pp. 244 u. 336.
WAGNER, Journ. f. prakt. Chemie, Bd. 45, P. 241.
BERTHELOT, Compt. rend., 1857, T. 44.
HOFMANN, Aerztl. Verein. zu Wieii., Mai, 1873.

— , Allgem. med. Centralbl., 1873, P. 605.
DDCLAUX, Theses presentees a la faculte de Paris, 1865.
DUBRUNFAUT, Compt. rend., 1871, T. 73.
LEX, Centralbl. f. d. med. Wiss., 1872, P. 291.
PANUM, Nbrd. med. Ark., 10, P. 4.
MOSLER, Mykologische Studien am Hiihiierei. Virch. Arch..

Bd. 29, P. 510.

HUFNER, Journ. f. prakt Chemie, K F. 10, P. 148.
COLIN, Annal. d. Chim. et Phys., 28, p. 128 ; 30, p. 42.
HOPPE-SEYLER, Arch. f. Phys., 12.
— , Medic, cheni. Untersuchuiigen, 1871, H. 4.
— , Zeitschr. f. physiolog. Chemie, Bd. 2.
BAUMANN, Ibid., Bd. 5, P. 244.
FLECK, Ber. d. chem. Centralst. Dresden,' 1876.
KARSTEN, Chemismus der Pflanzenzelle. Wien, 1869.
HALLIER, Gahrungserscheinungen. Leipzig, 1867.
SCHUTZENBERGER, Die Gahrungserscheinungeii, 1874.
A. MAYER, Lehrbuch der Gahruiigschemie, 2 Aufl., 1876.
HARZ, Grundziige der alkoholischen Gahrungslehre. Munchcn, 1877.
NAGELI, Theorie der Gahrung. Miincheii, 1879.
BREFELD, Landwirthsch. Jahresber, 1874, Bd. 3. — Ibid., 1875, Bd.

4.— Ibid., 1876, Bd. 5.

FITZ, Berichte d. chem. Ges., 1873, Bd. 6, P. 48.— 1878, Bd. 10,

P. 276.— 1879, Bd. 11, P. 42 u. 498. ; Bd. 12, P. 474.— 1880,

Bd. 13, P. 1309.— 1882, Bd. 15, P. 857.— 1883, Bd. 16, P. 844.—

1884, Bd. 17, P. 1188.

PRAZMOWSKI, Untersuchuiigen iiber die Eiitwicklungsgeschichte

und Fermentwirkung einiger Bakterien. Leipzig, 1880.
TYNDALL, Essays on the floating matter of the air in relation to

putrefaction and infection. London, 1881 .
ERIKSSON, Unters. aus d. botan. Institut in Tubingen, 1881, Heft 1.

LITERATURE. 4-7

POPOFF, Botan. Jahresber, 1875.

KONIG, Berichte d. deutsch. chem. Gesellsch., B. 14,

LACTIC ACID FERMENTATION.

BOUTRON ET FRE"MY, Ann. de chim. et de phys. (3), T. 2.

PASTEUR, Ibid. (3), T. 52.

LEBOLT, Journ. f. prakt. Chemie, Bd. 77.

PROUST, Ann. de chim. et de phys. (2), T. 10.

LISTER, The cause of the putrefaction and lactic fermentation.

The Pharmac. Journ. and Transact., 1877.
BOUTROUX, Snr la fermentation lactique. Compt. rend., T. 86,

1878.

RICHET, Compt, rend., T. 88, 1879.
HUEPPE, Mitth. a. d. Ges. Amt., Bd. 2. — Deutsche med. Wocli.,

1884, Nr. 48.

BUTYRIC FERMENTATION, FERMENTATION OF CELLULOSE.

PASTEUR, Compt. rend., T. 52, 1861.

TRKCUL, Bacillus Amylobacter. Compt. rend., 1865, T. 61.— 1867,

T. 65.

— , Ann. des sc., ser. 5, T. 7, 1867.
VAN TIEGHEM, Developpement du Spirillum amyliferum. Bull.

de la Sos. bot. de France, 1879.

— , Sur la fermentation de la cellulose. Ibid., 1879, p. 25 — 30.
— , Compt, rend., T. 89, 1879.

— , Sur le Bacillus Amylobacter. Compt, rend., 1879, T. 88.
— , Identite du Bacillus Amylobacter et du Vibrion butyrique

de Pasteur.— Ibid., Compt. rend., 1879, T. 89.
— , Sur le ferment butyrique a 1'epoque de la houille. Ibid.,
1880.
— , Ueveloppement de 1'Amylobacter dans les plantes a 1'etat et

vie normale. Compt. rend., 1884, No. 6.
TAPPEINER, Celluloseverdauung. Fortschr. d. Med., I., 151 ; II.,

377, 416.

PRAZMOWSKI, Unters. iib. d. Entwicklungsgeschichte und Ferment-
wirkung einiger Bakterien. Leipzig, 1880.

AMMONIACAL FERMENTATION.

VAN TIEGHEM, Compt. rend., T. 58, 1864, p. 210.
FELTZ ET HITTER, Journ. de 1'Anat. et Phys., 1874.
PASTEUR, Compt. rend., T. 50, 1860.

48 LITERATURE.

PASTEUR, Ann. de chim. et de Phys., T. 64, 1862.

— , Bull, de 1'Acad. de med., 1876, No. 27.
TYNDALL, Compt. rend., T. 58, 1864.
MULLER, Journ. f. prakt. Chemie, Bd. 81.
COLIN, Bull, de 1' Acad. de med., 1875.
MUSCULUS, Ber. d. chem. Ges., 1874, P. 124.

— , Archiv. f. Phys. 12, P. 214.
HILLER, Centralbl. f. d. med. Wiss, 1874, P. 53.
BE"CHAMP, Compt. rend., 60, p. 445.
DUBELT, Arch. f. exp. Pathol. 5, P. 195.

PASTEUR ET JOUBERT, Compt. rend, de 1'Acad. d. sc., T. 83, 1876.
— , Ber. d. chem. Ges. 9, P. 1130.
V. JACKSCH, Studien iiber den Harnstoffpilz. Zeitschr. f. physiol.

Chemie, Bd. 5, 188].
GUIARD, These de Paris, 1883.
LUPINE ET Roux, Compt. rend., T. 101, 1885.
LEUBE, Ueber die ammoniakalische Harngahrung. Virch. Arch.,

Bd. 100, P. 540.
LADUREAU, Sur le ferment ammoniacal. Compt. rend., T. 99,

p. 877.
BILLET, Sur le bacterium urea. Ib., T. 100, p. 1252.

MANNITE FERMENTATION.

PASTEUR, Bull. de. la soc. chim., 1861.
MONOYER, These de Strassburg, 1862.
BE"CHAMP, Compt. rend., T. 93.

DEXTRAN FERMENTATION.

VAN TIEGHEM, Leuconostoc mesenterioides. Ann. d. sc. nat., 6

si'r., T. 7.

- — , Sur la gomme de sucrerie. Ibid.
SCHEIBLER, Ueber die Natur des Froschlaich. Zeits. f. Riiben-

7Aickerindustrie, 1874.

CIENKOWSKI, Die Gallertbildungen d. Zuckerriibensaftes. Charkow,
1778.

PUTREFACTIVE FERMENTATION.

(See " Putrid Intoxication, Ptomaines," p. 16).

HOITE-SEYLER, Zeitschr. f. phys. Chemie, Bd. 2.

— , Arch, f . d. ges. Physiol., Bd. 12.
BAUMANN, Ibid., Bd. 5—7.

NRXCKI, Uber den chemischen Mechanismus der Fauliiiss. Journ.
f. praktische Chemie, Bd. 17.

LITERATURE. 49

NENCKI, Ueber die Zersetzung der Gelatine und des Eiweisses bei

der Faulniss mit Pancreas. Bern., 1876.
SALKOWSKKI, Zur Kenntniss der Eiweissfaulniss. Ber. d. deutsch.

chem. Ges., XII., 107, 648 ; XIII., 189.
— , Zeitschr. f. physiol. Chemie, V., 424. ; IX., 8, 491.
BRIEGER (see p. 17).
SALOMONSEN, Die Faulniss des Blutes. Kopenhagen, 1877

(Danish), Just, Jahresbericht fiir 1877, P. 222.
KAUFMANN, Zersetzung des Blutes durch Bacillus subtilis. Journ. f.

prakt. Chemie, Bd., 17, 1878.
ROSENBACH, Giebt. es verschiedene Arten von Faulniss ? Deutsche

Zeitschrift fiir Chirurgie, XVI., P. 342, 1882.
ETARD ET OLIVIER, De la reduction des sulfates par les etre

vivants. Compt. rend., 1882, p. 846.
BIENSTOCK, Ueber die Bakterien der Faeces. Zeitschr. f. klin.

Med., Bd. 8.
ESCHERICH, Die Darmbakterien des Neugeborenen und Sauglings.

Fortschritte der Med., Bd. 3, P. 515.
HAUSER, Ueber Faulnissbakterien. Leipzig, 1885.
TAPPEIXER, Medic. Centralbl., 1884.

DECOMPOSITION OF MILK (See p. 47).
HiippE, Unters. lib. die Zersetzangen der Milch durch Mikroorganis-

men. Mitth. a. d. Ges. Amt., Bd. 2, 1884.
— , Deutsche med. Wochenschr., 1884, Nr. 48 ff.
DUCLAUX, Ann. de 1'Institut agronomique, 1882.
FUCHS, Zur Kenntniss der gesunden und fehlerhaften Milch der

Hausthiere. Gurlt's u. Hertwig's Mag. f. d. ges. Thierheilk., Bd.

7,2.

HERMSTADT, Ueber die blaue und rothe Milch. Leipzig, 1833.
STEIXHOFF, Ueber das Blauwerden der Milch. Neue Ann. d.

meklenb. laiidw. Ges., 1838.
CHABERT et FROMAGE, D'une alteration du lait de vache, designee

sous le nom du lait bleu. Paris, 1850.
GIELEN, Mag. f. ges. d. Thierheilkunde., Bd. 18, 1852.
MOSLER, Ueber blaue Milch und durch deren Genuss herbeige-

fiihrte Krankheiten. Virchow's Archiv, Bd. 43, 1868.
NEELSEX, Cohn's Beitr. z. Biologic d. Pflanzen., Bd. III., Heft 2.
HUGUES, Le lait bleu. Echo veterinaire. Liege, 1884.
ScHMiDT-MuHLHEiM, Unters. liber fadenziehende Milch. Arch. f.

die ges Physiol., T. 27, P. 490—510.
KERX, Ueber ein neues Milchferment aus dem Kaukasus. Bull.

de. la Soc. Imp. des Naturalistes de Moskau, 1881, No. 3.

4

50 LITERATURE.

KERN, Dispora caiicasica, eine neue Bakterienform. Biolog. Cen-

tralbl., Bd. 2, P. 137.
MANDOWSKY, Deutsche med. Woch., 1884.
KRANNHALS, Ueber das kumysahnliche Getrank Kephir. Deutsches

Arch. f. klin. Med., Bd. 35, 1884.

OTHER DECOMPOSITIONS.

GAYON, Sur les alterations des oeufs. Compt. rend., 1877, T. 85.
BE"CHAMP ET EUSTACHE, Ibid., 1877, T. 85, p. 854—857 ; p. 1290—

1292.
MARCANO, Fermentation de la fecule. Presence d'un vibrion dans la

graine de mais qui germe et dans la tige de cette plante. Compt.

rend., 1882, p. 345.
PRILLIEUX, Corrosion de grains de ble colores en rose par des

Bacteries. Bull, de la Soc. Bot. de France, 1879, p. 31.
— , Ibid., p. 187—189.
JOLY, Etudes nouvelles tendant a etablir la veritable nature de la

glairine ou baregine. Compt. rend., 1882, T. 95, No. 24.

UNORGANISED FERMENTS.

MAYER, Die Lehre von den chemischen Fermenten. Heidelberg,

1882.

BARANETZKY, Die starkenmbildenden Fermente, 1878.
KRAUCH, Landwirthsch. Versuchsstation, 1879, Bd. 23.
SCHUTZENBERGER, Die Gahrungserscheinungen, 1876.
MAYER, Landwirthsch. Versuchsstation, 1871, Bd. 14.
GAYON, Compt. rend., 1878, T. 86, p. 52.

— , Bull. soc. chim., T. 35.
DUCLAUX, Compt. rend., T. 91.
DONATE, Ber. d. chem. Ges., 1875, p. 286.
BARTH, Ibid., 1878, p. 474.

NAGELI, Sitzber. d. Bayr. Akad. d. Wisp., 1878, H. 2, S. 177.
BERTHELOT, Compt. rend., 50, p. 890.
HOPPE-SEYLER, Ber. d. chem. Ges., 4, p. 810.

— , Arch. f. Phys., Bd. 12.

v. GORUP-BESANEZ, Ber. d. chem. Ges., 1874, Bd. 7.— 1875, Bd. 8.
A. SCHMIDT, Ueber Emulsie., &c. Diss. Tubingen, 1871.
v. D. HORST, Chem. Centralbl., 1878, P. 279.
KRUKENBERG, Unters. des physiologischen Institnts zu Heidelberg.

2, P. 273.

WURTZ ET BOUCHUT, Compt. rend., 89, p. 425; 90, p. 1379.
BODCHUT, Compt. rend., 91, p. 67.

LITERATURE. 51

DUCLAUX, Compt. rend., T. 91, p. 731.

KUHNE, Unters. aus dem phys. Institut z. Heidelberg, Bd. 1.

— , Centralbl. f. d. med. Wiss., 1878, P. 357.
v. NEXCKJ, Ber. d. chem. Ges., 9, P. 295.

SCYMANSKI, Zur Kenntniss des Malzpeptons. Chem. Ber., Bd. 18.
WORTMANN, Ueber das diastatische Ferment der Bakterien. Ztschr.
f. physiol. Chemie, 1882, Bd. 6.

— , Biol. Centralbl., Bd. 3.

PRODUCTION OF DISEASE.

GENERAL LITERATURE.
LI, Die niederen Pilze. Miinchen, 1877.

BUCHNER, Die Nageli'schen Theorie der Infect ionskrankheiten.

Leipzig, 1877.
KOCH, Unters uchungen liber Wundinfectionskrankheiten. Leipzig,

1878.

BILLROTH, Coccobacteria septica. Berlin, 1874.
KLEBS, Beitrage zur Anatomic der Schnsswunden. Leipzig,

1872-73.— Arch. f. exp. Pathol. n. Pharm., Bd. 1 — 16.—

Artikle ; " Ansteckende Krankheiten " in Eulenbnrg's Real-

Encyclopadie.
WKKXICH, Die Entwicklung der organisirten Krankheitsgifte.

Berlin, 1880.
Bn.-HNER, BOLLINGER, SOYKA u. A., Vortrage a. d. arztl. Verein in

Miinchen, 1881.
VIRCHOW, Krankheitswesen u. Krankheitsursachen. Virchow's

Archiv, Bd. 79.

HILLER, Berl. klin. Wohnschr., 1877.
FRISCH, Experimentelle Studien iiber Verbreitung der Faulniss-

organismen in den Geweben. Erlangen, 1874.
BKLFIELD, On the Relations of Micro-organisms to Disease. The

Mod. Rec., Vol. 23, 1883, No. 9—16.
RAM>H, On the Occurrence of Bacteria in Living Plants. Trans-

act. of Roy. Soc. of Victoria, T. 20, 1884.
TRAUBB u. GSCHEIDLEN, Ueber Faulniss u. den. Widerstand der

lebenden Organismen gegen dieselbe. Schles. Ges. f. vater-

liindische Cultur, 1874.
RIHBERT, Die Schicksale der Osteomyelitiskokken im Organismus.

Deutsche med. Woch., 1884, P. 682.
Co UN, Rech. exper. sur la conservation temporaire des virus dans

1'organisme des animaux ou ils .sont s.ins action. Compt. rend.,

T. 99, p. 759.

52 LITERATURE.

v. BERGMANN, Ueber eine Blutveranderung bei den acuten In-

fectionskrankheiten. Yerhandl. des Chirurgencongresses, 1882.
BOSSBACH, Mikrokokken nach Papayotin-Einspritzungen. Centralbl.

f. die med. Wiss., 1882.

SALOMONSEN, Pseudoinfection bei Froschen. Fortsclir. d. Med., II., 617.
SCHOU, Untersuchungen iiber Vaguspneumonie. Fortsclir. d. Med.,

III., Nr. 15, 1885.

ROSENBERGER, Centralbl. f. d. med. Wissensch., 1882.
METSCHNIKOFF, Ueber die Beziehung der Phagocyten zu den

Milzbrandbacillen. Virchow's Arch., Bd. 97, P. 502—526.—

Ibid., Bd. 96, P. 177.
VIRCHOW, Der Kampf der Zellen rind der Bakterien. Vircli.

Arch., Bd. 101, Heft 1.
RIBBERT, Ueber das Vorkommen von Spaltpilzeii in der normalen

Darmwand des Kaninchens. Deutsche med. "VVochenschr., 1885,

Nr. 13.
— , Weitere Untersuchungen iiber das Schicksal pathogener

Pilze im Organismus. Deutsche med. Wochenschr., 1885, Nr. 31.
FALK, Verhalten von Infection sstoffen im Verdauungskanale. Arch .

f. pathol. Anat. u. Phys. u. f. klin. Med., 93, 1883, Nr. 2.
NEPVETJ, Uebergang von Bakterien durch die Darmwand bei

Darmstrictur. Soc. de biol., 1883.
ESCHERICH, Bakteriolog. Unters. iiber Frauenmilch. Forts, d. Med:,

III., 231, P. 93a.

TRANSMISSION OF BACTERIA TO THE F<EITS.
STRAUSS ET CHAMBERLAND, Passage de la bacteridie charbonneuse

de la mere au foetus. Compt. rend., 1882, T. 95, Nr. 25.
KOUBASSOFF, Compt. rend, de 1'Acad. d. sc., 1885, Juli.
KOCK, Mitth. a. d. k. Ges.-Amt., Bd. II. Berl., 1884, P. 86.
LANDOUZY ET MARTIN, Faits cliniques et experimentaux pour servii-

a 1'histoire de 1'heredite de la tuberculose. Revue de med.,

1883, Dec.
JOHNE, Ein zweifelloser Fall von congenitaler Tuberkulose.

Fortschr. d. Med., Bd. 3, P. 198.

PASSAGE OF ORGANISMS INTO THE URINE (Microc. Urea?., See p. 47).
GTRAWITZ, Virchow's Arch., Bd. 70 (Schimmelpilzsporen).
KANNENBERG, Zeitschr. f. klin. Med., Bd. 1, 1830.
BABES, Wien. med. Wochenschr., 1884.
PASTEUR, Compt. rend., Vol. 56, 1863.
CAZENEUVE ET LivdN, Compt. rend., Vol. 85, 1877.
MEISSNER, Deutsche Zeitschr. f. Chir., Bd. 13, P. 344.
CHEYNE, Brit. Med. Journal, 1883.

LITERATURE. 53

LISTER, Transactions of the Roy. Soc. of Edinb., 1875.

NEXCKI u. GIACOSA, Journ. f. pract. Chem., N. F., Bd. 20.

LEUJ3E, Zeitschr. f. klin. Med., Bd. 3, 1881.

STRAUSS ET CHAMBERLAND, quoted in Centralbl. f. Gynakol, 1883

(Anthrax bacilli).
DUCLAUX, Bull, de 1'Acad. de Med., 1884, Ni\ 24 (Micrococci of

clou de Biskra).

WALTER, Bayer. Intelligenzbl., 1884 (Cocci in Diphtheric).
BALOGH, Wien. med Wochenschr., 1882 (Cocci in Scharlach).
EKLUND, Bayer. Intelligenzbl., 1884 (Cocci in Scharlach).
MARCKWALD, Inaug.-Diss. Konigsberg, 1872 (Bacteria in Septi-

cemia).

SENETZ, Petersb. med. Wochenschr., 1883 (The same).
WELCKER, Zeitschr. f. ration. Med., 1859 (Sarcina).
MUNK, Virch. Arch., Bd. 22, 1861.— Med. Centralbl., 1864 (Sarcina).
KUESSNER, Berl. klin. Wochenschr., 1876, P. 278 (Leptothrix).
HUBER, Deutsch. Arch. f. klin. Med., 1879 (Leptothrix).
WILSON, Centralbl. f. klin. Med., 1885 (Bacilli in Chylnria).
BENDA, Deutsche med. Wochenschr., 1884, P. 154 (Tubercle

bacilli in urine).

DITTEL, Centralbl. f. Chir., 1883 (The same).
DAMSCH, Deutsch. Arch. f. klin. Med., 1882 (The same).
BAUMGARTEN, Centralbl. f. d. med. Wissensch., 1883, P. 753 (The

same).

BOSENSTEIN, Ibid., P. 65 (The same).
BABES, Ibid., P. 9 (The same).
PHILIPOWICZ, Ueber das Auftreten pathogener Mikroorganismen

im Ham. Wien med. BL, 1885, Nr. 22 u. 23.

IMMUNITY AND PROTECTIVE INOCULATION.

TOUSSAINT, Bull, de 1'Acad. de Med., 1880, Juli— Sept.
— , Gazette Medicale de Paris, 1881, Nr. 32.
— , Compt. rend., 1880-81.
— , PASTEUR, Schutzimpfung bei Hiihnercholera, Bull, de 1'Acad.

de Med., 1880.— Gaz. Med. de Paris, 1880, Nr. 18.
— , Sur la Vaccination charbonneuse. Compt. rend., 1883.
— , La Vaccination charbonneuse. Paris, 1883.
— , Reponse au Doct. Koch. Revue Scientifique, 20 Jan., 1883.
CHAUVEAU, De la predisposition et de rimmunite pathologique.

Compt. rend., T. 89, 1879.
— , Du role de 1'oxygene de 1'air dans 1'attenuation quasi

instantanee des cultures virulentes par Faction de la chaleur.

Ibid., 1883, T. 96, Nr. 11.

54 LITERATURE.

CHAUVEAU, Ibid., 1883, T. 96, Nr. 10.
— , Ibid., 1883, T. 96, Nr. 9, p. 553—557.

— , De 1' attenuation des cultures virulentes par 1'oxigene corn-
prime. Gaz. hebdom. de med. et de chir., 1884, 22.
OLLIVE, Sur la resistance des moutons de la race berberirie a

1'inoculation du charbon. Compt. rend., 1879, T. 89.
PERRONCITO, Sull'attenuazione del virus carboiichioso. Atti R.

Ace. d. Lincei., Bd. 8, 1882-83.
CHAMBERLAND ET Roux, Compt. rend., 1883, T. 96, Nr. 15, p.

1088—1091.
CHAMBERLAND, Le charbon et la vaccination charbonneuse d'apres

les travaux recents de M. Pasteur. Paris, 1883.
MASSE, Des inoculations preventives dans les maladies virulentes.

Paris, 1883.

OEMLER, Arch. f. Wissensch. u. pract. Thierheilk, 1876 — 1881.
LOEFFLER, Zur Immunitatsfrage. Mitth. a. d. Ges.-Amt., Bd. 1.
KOCH, GAFFKY u. LOEFFLER, Exper. Studien iiber. d. kiinstl.

Abschwachung der Milzbrandbacillen. Mitth. a. d. Ges.-Amt.,

Bd. II.

KOCH, Ueber die Milzbrandimpfung. Cassel u. Berlin, 1882.
ROLOFF, Ueber die Milzbrandimpfung, &c. Arch. f. wissensch.

u. pract. Thierheilkunde, Bd. 9.
EGGELING, Die Resultate der nach der Pasteur' schen Methode

auf der Domane Packisch angestellten Milzbrand-Impfversuche.

Deutsche landwirthsch. Presse, Jahrg., 10.
BLAZEKOVIC, Zur Praventiv- Inoculation Pasteur's. Oesterr. Monat-

schr. f. Thierheilk, 1884.
ROSZAHEGYI, Ueber die mit Pasteur'scher Schutzimpfung gegen

Milzbrand in Ungarn ausgefiihrten Versuche. Pester, med., chir.

Presse, 1882.

FRANK, Jahresber. d. K. Thierarzneischule in Miinchen, 1882-83.
PUTZ, Vortrage f. Thierarzte, Ser. 7, Heft. 1, 1884.
HESS, Vorl. Mitth. ii. die Schutzimpfung gegen Milzbrand im

Kanton Bern nach der Methode Chauveau. Schweiz. Arch. f.

Thierheilk, Bd. 27.
ARLOING, CORNEVIN ET THOMAS, Du charbon bacterien ; Pathogen ie

et inoculations preventives. Paris, 1883.
STREBEL, Zur Rauschbrandimpfung. Schweiz. Arch. f. Thierheilk,

1885, 1.

SEMMER, Virchow's Arch., Bd. 83.

SEMMER u. KRAJEWSKI, Centralbl. f. d. med. Wissensch., 1880.
PASTEUR, Vaccination des Schweinerothlaufs. Bull, de 1'Acad. de

med., 1883.

LITERATURE. 55

GRAWITZ, Die Theorie der Schutzimpfung. Virchow's Arch., Bd.

84, 1881.
BUCHNER, Eine neue Theorie iiber Erzielung v. Immunitat gegen

Infectionskrankheiten. Miinchen, 1883.
WOLFFBERG, TJnters. znr Theorie des Impfschutzes, sowie iiber die

Regeneration der Pockenanlage. Erganz. Hefte z. Centralbl. f.

allgem. Gesundheitspflege I., Heft 4 ; Ibid., I., Heft 1.
FELTZ, De la duree de 1'immunite vaccinale anticharbonneuse chez

le lapin. Compt. rend., T. 99, p. 246, 1884.
BOULEY, L'inoculation preventive de la fievre jaune. Compt. rend.,

T. 100, p. 1276.

DISTRIBUTION OF THE MICRO-ORGANISMS.

V. FODOR, Hygienische Unters. iiber Luft, Boden, u. Wasser.

Braunschweig, 1882.

SMART, Germs, Dust, and Disease. Edinburgh, 1883.
KOCH, Vortr. a. dem. 11 deutschen Aerztetag, Juni, 1883.
NAGELI, Unters. iiber niedere Pilze. Miinchen, 1882.
BUCHNER, Die Bedingungen des Uebergangs von Pilzen in die

Luft. Zur Aetiologie der Infectionskrankheiten, Vortrage im

iirztl. Verein zu Miinchen, 1881.

WERNICH, Cohn's Beitrage z. Biol. d. Pflanzen, Bd. 3, 1879, p. 105.
SOTKA, Sitz.-Ber. der K. bayr. Akad. d. Wiss. Math. Physik.

Classe, 1881.

— , D. Vierteljsch f. off. Ges., Bd. 14, 1882.
— , Vortrage im arztl. Yerein in Miinchen. Miinchen, 1881.
PASTEUR, Compt. rend, de 1'Acad. d. sc., T. 50, 52, 56, 85.
— , Ann. de chim. et de phys., 3 ser., T. 64.
TYNDALL, Med. Tim. and Gaz., 1870.
— , Brit. Med. Journ., 1877.

— , Essays on the floating matter of the air. London, 1881.
POUCHET, Compt. rend., T. 47.
LEMAIRE, Ibid., T. 57.

MADDOX, Monthly Microscop. Journ., Vol. 3.
LIECHTENSTEIN, Berl. klin. Wochenschr., Bd. 11.
CUNNINGHAM, Microscopical Examination of the air. Calcutta, 1874.
TISSANDIER, Compt. rend., T. 78.
MIFLET, Unters. iiber die in der Luft suspendirten Bakterien.

Cohn's Beitr. z. Biol. d. Pflanzen, Bd. III.
EMMERICH, Ueber die Bestimmung der entwicklungsfahigen Luft-

pilze. Archiv f. Hygiene, Bd. 1, Heft 2.
KLEBS u. TOMMASI-CRUDELI, Unters. der Luft auf die Mikro-

organismen der Malaria. Archiv f. exper. Path., Bd. 11, 1879.

M> I 1 IKRATURK.

V. SBHLEN, Fortachr. d. Mod., Bd. 2, P. 585.

HESSE, Ueber quantitative Best, der in der Luft onthaltenen

.MikroorpinisnuMi. Mittli. ;i. <1 Crs Ami , 1M. II.

— , Ueber Abscheidung d. Mikroorganiamen aua d. Luft. Deutsche
mod. Wochensohr., 1884, 2.
— , Weitere M i u 1 1 . ii 1 >or Luf ttiltration. Deutsche ined. Wochensohr.,

1884, Nr. 51.

MKH-KI.. rompt. iviul.. T. Sl>.

— , Do la prtaenco daiw 1'air da ferment de 1'uree. Bull, do 1ft
Soc. chini., 1878.
— , Ann. d'hygiene, 1879.

—, Annuaire de rObservat. de Montsouris, 1877 — 82.
— , Lea organiames vivanta de I'atmosphere. Paris, 1883.
QIACOSA, Let corpusc. organ, do 1'air dos hautos montagnes. Arch.

ital. de Biol., T. 3.

MiguKL KT FRKUDKNRKICH, La somaine m^dicale, 1884.
OLIVIER, Lea germes de 1'air. These. Rov. scientif., 1883.
MOKKAU KT PLANTYMAUSION, La semaiue Medicale, 1884.
FRBUDKNBEICH, Lea microbes de 1'air dea montagnes. Rev.

scientif., II., p. 384

KOCH, Verhandl. der Cholei«aoonferenz., 1884 u. 1885.
v. PKTTENKOPKR, Verhandl. der Choleraconfei^enz., 1885.
LBTEERICH, Kxp. Unters. iib. die Aetiologie des Typhus mit bes.

Borucksiohtigung der Trink- u. Gebrauchswiisscr, 1883*
ZANDER, Centralbl. f. allg. Ges., 1883, 2.

ANGUS SMITH, On the examination of waters. Soc. Hep. to the
Local Government Board. London, 1884.
— , Sanit. Record, 1883, Febr.
GUNNING, Beitr. z. hygienischen Untersuchung des Wassers. Arch.

f. Hyg., 1883, 3.
WINNACKER, Ueber die in Rinnsteinen beobacht. nied. Or.<rnnisinen.

Gdttinger Inaug.-Diss. Frankfurt a. M., 1882.
DIKW.VSSKKVIMJSOU. ; N \.'\ 7.u;K-u./.i;.-ii'li, lSs:>. ^Hoivin a

by C(«mvr M to the presence of bacteria in various watoi-
BKOKER, Reichsmedicmalkalender, 1985.
FOL ET DUNANT, Aix;h. del sc. phys. et natur. Bibliothoipio nuivor-

selle de Geneve, T. 13, 1885, Febr.
CHAMBKRLAND, Sur un filtre donnant de 1'eau physiolo^iquoment

pure. Compt. rend., T. 99, p. 247.

HESSE, Ueber Wasaerfiltration. Deutsche med. Woch., 1885, Nr. 5.
WOLLNY, Ueber die Thatigkeit niederer Oi'ganismen im Bodeu.

Vierts f. off. Ges., 1883, P. 7u,V

l:uul\%irlhsohaftl. Tivssr, Inl J>.

LITERATURE. 57

Ueber d. chem. Vorgange im Boden u. Grand-

wasser u. ihrc hygienische Bedentung. Arch. f. off. Gesdhtepfl.

in Lothringen, 1883.
SOYKA, Die Lebensthatigkeit niederer Organismen bei wechselnder

Bodenfeuchtigkeit. Prager med. Woch., 1885, Nr. 4.
K'I';II, Milzbrandbacillen im Boden. Mitth a. d. Ges.-Amt., Bd. 1,

P. 65 ff.

S* HKAKAMP, Archiv f. Hygiene, Bd. 2, 1884.

CK<;J, Maluriakeime im Boden. Arch. f. exp. Pathol., Bd. 15 u Ifi.
TOKKLLI, La malaria in Italia. Roma, 1883.
EMMERICH, Die Vemnreinignng der Zwischendecken unsrer Wohn-

riiume. Ztschr. f. Biol., Bd. 18.
— , Pneumoniekokken in der Zwischendeckenfullang. Arch, fur

Hyg., Bd. 2, Heft 1.
(fKA^si, 1 malefizi delle mosche (Distribution of bacteria by

Flies). Gaz. degli Ospitali, 1883.
MAiti'MANN, Die Verbreitung von Spaltpilzen durch Fliegen. Arch.

fur Hygiene, Bd. 2, Heft 3.

Hu.i.:.::, Sojiti.-.r-he Infection durch Insekten. Inaug.-Diss. Tubin-
gen, 1883.
Di :CLAUX, PASTEUR, Stoffwechsel bei Ausscliluss von Mikroorganis-

men. Compt. rend., 1885, Nr. 1.

DISINFECT i -»N.
General.

LEX, Roth u. Lex, Militargesundheitspflege.
, Vierteljahrschr. f. offentl. Ges., Bd. 4.
I']-' jiKii, Article " Desinfection " in the Neuen Handworterbuch

der Chemie.

WKRMCH, Grundriss der Desinfectionslehre. Wien u. Leipzig, 18^ >.
NAGELI, Die niederen Pilze. Miinchen, 1877.
S ••Jiicoi ut, Cohn's Beitr. zur Biol. der Pflanzen, Bd. I., Heft 3.
KM.JH, Ibid., Bd. II., Heft 2.

— , Ueber disinfection. Mittb. a. d. Ges.-Amt., Bd. 1, P. 234.
I .~iia< no.vs FOIJ Disrv! ijjnoN, prepared for the ^National Board of

Health, New York, 1879.
PLAUT, Desinfection der Viehstalle. Leipzig, 1884. Verl. v. H.

Voigt.

STEINMEYKK, Ueber Desinfectionslehre. Braunschweig, 1884.
W. CHEYXE, Antiseptic Surgery, its principles, practice, history.

and results. London, 1882.
FORSTER, Wie soil der Arzt seine Hande reinigen ? Centj-albl. f.

klin. Med., 188.5, Nr. 18.

58 , LITERATURE.

MILLKR, Die Anwendbarkeit einiger Antiseptica bei der Behandlung
der Krankheiten der Mundhohle u. d. Zahne. Deutsche med.
Wochenschr., 1885, Nr. 32.

MIQUEL, Antiseptiques et bacteries. Semaine medicale, 1883.
— , Annuaire de 1'observatoire de Montsouris pro 1884.

CHAUVEAU, Compt, rend., 1883, 1884.

CHAMBERLAND ET Roux, Ibid., 1883.

PERRONCITO, Sur la tenacite de vie du virus charbonneux. Arch,
ital. de biol., 1883.

TALLIN, Traite des disinfectants et de la disinfection. Paris, 1883.

RATIMOFF, Revue Scientif. I., p. 797.

BUCHOLTZ, Antiseptica u. Bakterien. Klebs' Archiv f. exp. Path.,

Bd. 2 u. 4.

— , Ueber das Verhalten von Bakterien zu einigen Antisepticis.
Dorpat, 1876.
— , Arch. f. exp. Pathol., Bd. 7, 1877.

HABE-RKORN, Das Verhalten von Harnbakterien gegen einige Anti-
septica. Dissert. Dorpat, 1879.

DE LA CROIX, Das Verhalten der Bakterien d. Fleischwassers gegen
einige Antiseptica. Arch. f. exp. Pathol., Bd. 13, 1881.

SCHWARTZ, Sitzungsber. d. Dorpater Naturf.-Ges., 1879.

WERNICKE, Diss. Dorpat, 1879.

MEYER, Ueb. d. Milch saureferment u. sein Verhalten gegen Anti-
septica. Dorpat, 1880.

SCHOTTE u. GARTNER, Viertelj. f. off. Ges., 12, 337.

SALKOWSKI, Viertelj. f. ger. Med., 23, 375.

SOYKA, Ber. d. Bayr. Akad. d. Wissensch, 1879, Mai.

TOUSSAINT, Bull, de 1'Acad., 1880.

SCHILL u. FISCHER, Ueber die Desinf ection des Auswurf s der Phthi-
siker. Mitth a. d. Kaiserl. Ges.-Amt., Bd. II.

LEBEDEFP, Desinfectionsversuche am malignen Oedem. Arch. de.
physiol. norm, et pathol., 1882.

COLIN, Desinf. versuche mit Blut v. Cholera des poules. — Thieren.
Compt. rend., T. 99.

CHAIRY, Action des agents chimiques sur les bacteries du genre
Tyrothrix., ib., p. 980.

MODES OF DISINFECTION IN DETAIL.

HEAT AND COLD.
FRISCH, Ueber den Einfluss nied. Temp. auf. d. Lebensfahigkeit

der Bakterien. Sitzungsber. d. Wiener. Akad., Bd. 75 u. 80.
PICTET ET YO.UNG, De 1'action du froid sur les microbes. Compt.

rend., T. 98, 1884, p. 747.

LITERATURE. 59

EIDAM, Einwirkung versch. Temperaturen a. d. Entwicklung yon

Bacterium termo. Cohn's Beitr. zur Biol., Bd. 1, Heft 3.
LEBEDEFF, Arch, de phys. norm, et patliol., 1882, No. 6.
HEYDENREICH, Sur la sterilisation des Liquides au moyen de la

marmite de papin. Compt. rend., 1884, T. 98.
MERKE, Virchow's Archiv, 1880, Bd. 81.

— , Yiertelj. f. ger. Med., Bd. 37.
TYNDALL, Philos. Transact, of the Roy. Soc., 1877.
TALLIN, Ann. d'hyg., 1877.

HORNEMANN, Hygiejnske Mededelser, Ny. Baekke., III., 1.
MORSCHELL, Deutsche med. Wochenschr., 1880.
LASSAR, Ibid.

PASTEUR, Ann. d'hyg., 1880.

ARLOING, CORNEVIN ET THOMAS, Lyon medical., 1883.
KOCH u. WOLFFHUGEL, Unters. iib. die Desinfection mit heisser

Luft. Mitth. a. d. Kaiserl. Ges.-Amt.,Bd. I., P. 301.
HUEPPE, Ueber das Verhalten ungeformter Fermente gegen hohe

Temperatur. Mittheilg. a. d. Kaiserl. Ges.-Amt., Bd. I., P. 341
— , Ueber die Hitze als Desinfectionsmittel. Deutsche mili-

tararztl. Zeitschr., 1882.
KOCH, GAFFKY, u. LoFFLER, Versuche iiber die Verwerthbarkeit

heisser Wasserdampfe zu Desinfectionszwecken. Mitth. a. d.

Kaiserl. Ges.-Amt., Bd. I., P. 322.
VALLIN, Les nouvelles etuves a desinfection. Revue d'hygiene,

1883.

— , Ann. d'hygiene, 1877, 1884.
ROCHEFORT, HERSCHER, Revue d'hygiene, 1884.
M. WOLFF, Zur Desinfectionsfrage. Centralbl. f. d. med. Wissensch.

1885, Nr. 11.

SULPHUROUS ACID.

WOLFFHUGEL, Ueber den Werth der schwefligen Saure als Desin-
fectionsmittel. Mittheilg a. d. Kais. Ges.-Amt., Bd. I., P. 188.

LAILLIER, Du gaz acide sulfureux. Ann. d'hygiene, 1883.

DUJARDIN-BEAUMETZ, Bull, de 1'Acad. de med. de Paris, 1884,
September.

LEGOUEST, Ibid.

MARIE"-DAVY, Revue d'hygiene, 1884.

CHLORINE AND BROMINE.

FRANK, Bericht der 56 u. 57 Naturforscherversammlung.
— , Ueber Desinfection von Abtrittsgruben. Berlin, 1885,

Verlag. der deutschen Medicinal-Zeitung.
FISCHER u. PROSKAUER, Mitth. a. d. Kaiserl. Ges.-Amt., Bd. II.

60 LITERATURE.

WOLFFHUGEL U. KNORRE, Zu der verschicdcnen Wirksamkeit von

Carbolol u. Carbolwasser. Mitth. a. d. Kaiserl. Ges.-Amt., Bd.

L, P. 352.
WERNICH, Die aromatisclien Faulriissproduete in ihrer Einwirkung

auf Spalt. und Sprosspilze. Yirchow's Archiv, Bd. 78, 1879.
RENAUDOT (Borphenyl acid), Rev. sclent., II., p. 318.
BREMOND (Vapour of Turpentine Oil), Ann. d. hygiene, 1884, p. 344.
ROSSBACH, Einfluss des innerl. Naphtalingebrauchs auf die Harn-

faulniss. Berl. klin. Wochenschr., 1884.
-~, Fortscher. d. Med. Beilage, 215.
FISCHER, Uiiters. iib. d. Wirkung des Naphtalins. Berl. kliu.

Wochenschr., 1883.
REPOND (Salicylresorcinketon, &c.), Corr. f. Schweizer Aerzte.,

1883, Nr. 8.
REINL, Zur Theorie der Heilwirkung des Franzensbader Moores.

Prager med. Wochenschr., 1885, Nr. 10 u. 11.
ROHAT (Sulphate of Iron), Compt. rend., 1883.
CREDE (2% Arg. nitr. against Blennorrhoea neonat.), Arch. f.

Gynakol., Bd. 21.

LEWIN, Die Borsaure. Inaug. Diss., Bonn, 1883.
SCHEDE, Die antiseptische Wuiidbehandlung mit Sublimat.

Sammlung klin. Vortrage, Nr. 251, 1885.
KONIG, Sublimatdampfe. Chirurg. Centralbl., 1885.
LARRIVE", L'eau oxygenee. These de Paris, 1883, Jan.
MALY u. EMICH, Antisept. Wirkung der Gallensauren. Sitzungsber.

d. kais. Akad. d. Wiss. zu Wien., 1883, Jan.
SCHULTZ, Die antiseptischen Eigenschaften der Citronensaure.

Deutsche med. Wochenschr., 1883, NY. 17.
HOFFMANN, Experimentelle Untersuchungen iiber die Wirkung der

Ameisensaure. Dissertat. Greifswald, 1884.
THOL, Ueber d. Einfluss nicht aromat. organ. Sauren auf Faulniss

u. Gahrung. Dissertat. Greifswald, 1885.
SCHULZ, Die Ameisensaure als Antisepticum. Deutsche med.

Woch., 1885, Nr. 24.
SCHNETZLER, Les proprietes antiseptiques de 1'acide formique.

Archiv de Geneve, Jan., 1884.

CONSTANCY AND VARIABILITY OF THE VARIOUS
SPECIES OF BACTERIA.

BILLROTH, Unters. iib. d. Vegetationsformen der Coccobacteria
septica. Berlin, 1874.

LITERATURE. 61

KLEBS, Article "Ansteckende Krankheiten " in Eulenburg's Real-
Encyclopadie, and numerous other articles in the Archiv f. exp.
Pathol.
NAGELI, Die niederen Pilze, 1877.

— , TJnters. iiber niedere Pilze. Miinchen, 1882.
BUCHNER, Sitzungsber. d. Ges. f. Morphol. u. Physiol. zu Miinchen,
1855, Heft I.

— , Virchow's Arch., Bd. 91.

— , Vortrage im arztl. Yerein. zu Miinchen, 1881.

— , Die JSTageli'sche Theorie der Infectionskrankheiten. Leipzig,

1877.

GRAWITZ, Virchow's Archiv, Bd. 81.

ZOPF, Ueber den genetischen Zusammenhaiig von Spaltpilzformen.
Sitzungsber. d. Berl. Akad. d. Wissench., 1881.

— , Zur Morphologic der Spaltpflanzen. Leipzig, 1882.

— , Deutsche med. Wochenschr., 1885, Nr. 4.
ZOPF u. MILLER, Arch. f. exp. Pathol., 1882.
MILLER, Archiv f. exp. Pathol., Bd. 14.

— , Deutsche med. Wochenschr., 1884, Nr. 36.
NEELSEN, Cohn's Beitr. z. Biol. d. Pflaiizen, Bd. 3.

— , Neuere Ansichten iib. d. Systematik d. Spaltpilze. Biolog.

Centralbl., III., Nr. 18.

VANDEVELDE, Zeitschr. f. physiol. Chemie, Bd. 8.
ROLOFF u. ARCHANGELSKI, Centralbl. f. d. med. Wiss., 1882, 1883.
FOKKER, Ibid., Bd. 18, 19.
V. JACKSCH, Zeitschr. f. phys. Chemie, Bd. 5.
VAN TIEGHEM, Compt. rend., 1879.
HAUSER, Ueber Fiiulnissbakterien. Leipzig, 1881.
KOCH, Mitth. a. d. Kaiserl. Ges.-Amt., Bd. I., P. 49.
GAFFKY, Ibid., Bd. I., P. 80.

FLUGGE, Deutsche med. Wochenschr., 1884, Nr. 46.
HUEPPE, Fortschr. d. Med., 1883, Nr. 6.
BIEDERT, Virch. Arch., Bd. 100, P. 439.

METHODS.

{For further Literature, tee Hueppe's " tifethodik")
MICROSCOPIC EXAMINATION.

KOCH, Untersuchungen iiber Wundinfectionskrankheiten. Leipzig,

1878.

— , Verfahreii zur Untersuchung, zum Conserviren und Photo-
gi-aphiren der Bakterien. Cohn's Beitr. z. Biol. d. Pflanz., Bd.
II., 3. Heft, 1877.

62 LITERATURE.

KOCH, Zur Untersuchung von path. Orgaiiismen. Mitth. a. d.

K. Ges.-Amt,, Bd. I., 1881.
WEIGERT, Schnittpraparate. Virchow's Arch., Bd. 84, 1881.

— , Sitzungsber. d. Schles. Ges. f. vaterl. Cultur., 10 Dec., 1875.
ABBE", Ueber Stephenson's System der homogenen Immersion.

Sitzungsber. d. Jenaischen Ges. f. Med. u. Naturw., 1879, 10 Jan.
EHRLICH, Zeitschr. f. klin. Med., Bd. I., 1880, P. 553.— Bd. II.,

Heft 3.

— , Deutsche med. Wochenschr., 1882, NT. 19.
SCHWARZE, Ueber eosinophile Zellen. Dissert., Berlin, 1880.
WESTPHAL, Ueber Mastzellen. Dissert., Berlin, 1880.
GRAM, Ueber die isolirte Farbung der Schizomyceten. Forts, d.

Med., II., 1884, NT. 6.

FRIEDLANDER, Mikroskopische Technik, 2 Aufl., 1884.
BUCHNER, Ueber das Verhalten der Spaltpilzsporen zu den Anilin-

farben. Aerztl. Intelligenzbl., 1884, NT. 33.
BAUMGARTEN, Beitr. zur Darstellnngsmethode der Tuberkelbacillen.

Zeitschr. f. wissensch. Mikrosk., I., 1884, p. 51.
— , Ueber Untersnchungsmethoden zur Unterscheidung von

Lepra und Tuberkelbacillen. Zeitschr. f. wissensch. Mikrosk.,

Bd. I., Heft 3.
FUTTERER, Ueber eine Modification der Ehrlich'schen Farbeme-

thode fur Tuberkelbacillen. Virch. Arch., Bd. 101, 1885.
PLAUT, Farbungsmethoden znm Nachweis der Mikroorganismen.

2 Aufl. Leipzig, 1884.
BEHRENS, Hilfsbuch zur Ausfiihrung mikroskopischer Untersuch-

ungen, 1883.

HUEPPE, Die Methoden der Bakterienforschung. Wiesbaden, 1885.
BIZZOZERO ET FIRKET, Manuel de Microscopic clinique. 2 ed., Paris-

Bruxelles, 1885.

METHODS OF CULTIVATION.

KLEBS, Ueber fractionirte Cultur. Archiv f. exp. Pathol., Bd. I.,

1873.
KOCH, Zur Untersuchung von pathogenen Organismen. Mitth. a.

d. Kaiserl., Ges.-Amt., Bd. I., 1881.

— , (Blood serum) Berl. klin. Wochenschr., 1882, NT. 15.
— , Mitth. a. d. Kaiserl. Ges.-Amt., Bd. 2, 1884.
BREFELD, Methoden z. Unters. der Pilze. Verhandl. d. physik med.
Ges. in Wiirzburg. 1ST. F., Bd. 8, 1874-75.

— , Kulturmethoden z. Untersuchung der Pilze. Bot. Unters.
iiber Schimmelpilze, Bd. IV., 1881.

LITERATURE. 63

BREFELD, Die kiinstl. Kultur parasitischer Pilze. Bot. Unters.

iiber Hefepilze, Bd. 5, 1883.
FEHLEISEN, Ueber neue Methoden der Untersuchung u. Cultur

pathogener Bakterien. Physik. med. Ges. zu. Wiirzburg, 1882, p.

113—121.

PASTEUR, Etudes sur la biere, 1867.
BUCHNER, In Nageli's Untersuchungen iiber niedeie Pilze. Miin-

chen, 1882.
SALOMONSEN, Znr Isolation differenter Bakterien. Bot. Zeitg.,

1879, Nr. 39.
— , Eine einfache Methode z. Reincultur versch. Faulnissbak-

terien. Ib., 1880, Nr. 28.
JOHNE, Ueber die Koch'schen B/eincnlturen und die Cholerabacil-

len. Leipzig, 1885.
As to Anaerobiosis see p. 43. For the investigation of air, water,

and soil, see under "Distribution of the Micro-organisms," p. 55.

INTRODUCTION.

IN the outer world with which mankind is in daily con- Significance
tact, and which forms the subject of hygienic research, organisms.
the attentive observer finds micro-organisms widely dis-
tributed and only just visible with the aid of the best
optical means; these bodies, however, on account of
their silent yet widespread and energetic activity, play
an important part in the economy of nature and in the
existence of mankind. They occasion the destruction
of dead organic material, they cause the oxydation of
substances otherwise very resistant, and constantly pro-
vide new nutriment for chlorophyllous plants ; they set
up the most varied fermentations, and are indispensable
aids in the preparation of our ordinary nutritious and
savoury food ; on the other hand they attack our plants
as parasites, bringing degeneration and death to their
hosts ; at times they cause the severest diseases in the
lower and higher animals, and threaten even man with
fatal epidemics. In no department of hygiene is their
influence missed ; in the air, in the water, in the soil,
in our immediate surroundings, in our dwelling, and
in our food, the same minute organisms are present
as constant companions, and at times as dangerous
foes.

The majority of these important yet minute bodies Synonyms.
are plants of the most elementary structure and with
the most simple mode of propagation, but yet with
extraordinary powers of multiplication. They are
grouped together under the headings "micro-organisms "
or "microbes"; at times they are designated a^
"lower fungi" or as "bacteria." Further, various
terms are applied to particular groups of these organ-
isms according to the particular mode of action to
which attention is directed. Thus, from the physio-

5

G6 INTRODUCTION.

logical chemical standpoint, they have heen termed
"organised ferments"; on the other hand, from the
special pathological point of view, " parasitic plants "
or "micro-parasites."

The object of the present work is to describe the form
and vital characteristics of these micro-organisms in so
far as they have a direct or indirect interest from a
hygienic point of view.

The method The plan of this work embraces in the first place a
n' short historical sketch of the development of our know-
ledge with regard to the ferments and parasites during
the last few years. Then follows a description of the
form and mode of development of those micro-organisms
which are important from a hygienic standpoint, and also
a short morphology and classification, a knowledge of
which is indispensable for the comprehension and the
further successful study of these bodies, so difficult
to recognise and to distinguish one from the other.
Nor is the biology of the micro-organisms less instruc-
tive; hence the third part deals with the general
conditions of life of the lower fungi ; in the fourth are
described the results of their life, their tissue change,
and energy, as well as their action as exciting agents of
fermentation and of parasitic diseases; and the fifth
chapter deals with the conditions of decay of the micro-
organisms and with the means which cause their
enfeeblement or death.

In the sixth and seventh divisions the points which
are of special interest in hygiene are referred to ; in the
sixth the distribution of the various micro-organisms in
our surroundings, in air, soil, water, food, and dwelling ;
and in the seventh there is given a digest of the
conclusions to which we must come with regard to
the etiology and prophylaxis of the infective diseases.
The contents of this chapter include the discussion of
the external sources of infection, of the local and
seasonal predisposition to infective diseases, of the
mode of entrance of the infective agents into the
organism and their fate in the body, of the means by
which it is possible to obtain protection against the

INTRODUCTION. 67

clanger of infection and to overcome it, of immunity
and protective inoculation, of the general prophylactic
rules, and of the modes of disinfection suitable in
practice.

Finally, in the last chapter there is added a sketch of
those methods of investigation which are most useful
in the study of this most difficult department of hygiene.

PART I.

THE PROG11ESS OF KNOWLEDGE WITH REGARD TO THE
FERMENTS AND MICRO-PARASITES DURING RECENT YEARS.

THE first undoubted observation as to the existence of The earliest

-,.... . _. observations

small microscopical living beings in our surroundings was with regard
made by Ehrenberg, who found numerous organisms
in water and in dust, and designated them " Infusion
animals (Infusionsthierchen, 1828)." Eight years later
the vegetable nature of yeast was discovered by Caignard-
Latour and Sclnvann, although the cell form had been
seen much earlier (first by Leeuwenhoek, 1680), and
their organised and vegetable character had been sus-
pected by several investigators (Thenard, Persoon).
Schwann also, in the year 1837, asserted as the result
of experiments, that the atmospheric air was constantly
laden with fermentative and putrefactive germs, and also
that certain fermentative processes were dependent on
the access of living organisms.

From that time dates the lasting and active interest
in micro-organisms, and the development of the subject
has chiefly taken two different directions : on the one
hand, the problem investigated was the relation between
the fermentative germs and the processes of fermentation
and putrefaction ; on the other hand, the attempt was
made to demonstrate a causal connection between similar
minute living bodies and infective diseases in man and
animals, a connection which various hypotheses and
analogies rendered probable. It is only possible to
follow the numerous controversies with regard to the
significance of the micro-organisms by tracing separately
the gradual development of knowledge, on the one hand
with regard to fermentation, and on the other with regard
to parasitic growth.

70 FERMENTS AND MICRO-PARASITES.

I. MICRO-ORGANISMS AS THE EXCITING AGENTS OF
FERMENTATION AND PUTREFACTION.

Gradual Development of the Vitalistic or Germ Theory.

Before Schwamrs discovery the essence of the ferment-
the°organic ative process — and especially of the alcoholic or vinous
yeast ° fermentation in which sugar is broken up into alcohol

and carbonic acid — was by some not at all associated
with the yeast, which was looked on as only an acci-
dental accompaniment ; by others the role of the yeast
was regarded as an etiological one, but only in the sense
that the mass of these cells acted as a porous body
which easily condensed the oxygen, passed it over to the
other substances, and thus occasioned the decomposition
of the sugar (Braconnot, 1831), or that the yeast pos-
sessed catalytic properties, and thus had the power of
splitting up the fermentescible substances in the same
way as peroxide of hydrogen is decomposed by finely
divided platinum, &c. (Berzelius, 1827). Up to this
time no one had held the view that the process of fer-
mentation was closely connected with the living multi-
plying yeast cells, and was in fact the result of their
life, and no one could hold such a view previously,
because the organised nature of yeast w<as not yet
known. Schwann was the founder of the vitalistic or
germ theory. As the result of new experiments he
asserted that the cause of the fermentation was the
vegetation and multiplication of the living yeast in the
fermentescible fluid, that the yeast cells took from it
the materials necessary for their growth, and that the
elements which were not taken up by the yeast became
grouped together principally in the form of alcohol.
Schwann's experiments were repeated several times in
the course of the next few years, and the results were
confirmed and extended ; among the more immediate
advances it is only necessary to mention the proof
furnished by Liidersdorff that triturated yeast cells are
inoperative, and that only intact cells can produce fer-
mentation, and also the observation by Blondeau that

GRADUAL DEVELOPMENT OF THE GERM THEORY. 71

different fermentations are caused by different kinds of
micro -organisms.

The strict proof that living yeast cells or minute Evidence re-
organisms similar to yeast are the only cause of every prove^he cb-
fermentation, could however only be furnished by a pendence of

y r fermentation

series of experimental investigations, which must have on living
for their aim the following questions : — •

1. In the first place it was necessary to show that i. Living cells
germs are present in all fermenting and putrefying fnan'fennent-
fluids. This was proved by all the investigators who in£ fluids-
busied themselves with the question of fermentation

after Schwann, and in fact it was the constant presence
of definite microscopical organisms which formed the
starting point of the vitalistic theory. The fact itself
was much less disputed by the adversaries of this theory,
than its meaning. Not till later years were here and
there observations published which asserted the exist-
ence of putrefying and fermenting media without micro-
organisms — observations which will be considered in
detail later.

2. From the constant concurrence of putrefaction and 2. Fermen-
micro-organisms the causal role of the latter did not stances do not

of course directly follow; that must on the

be proved by special experiments. The behaviour of of living yeast

ferinentescible substances without micro-organisms was vented.

therefore tested in the first instance ; and for this

purpose the attempt was made to kill any germs which

might be present in the substances themselves, in the

vessels, &c., by a temperature of at least 100° C., care

being then taken to protect the materials against the

entrance of fresh germs, either by suitable methods of

closing the vessels, or by subjecting the entering air to

the action of means which could kill the germs.

These experiments also date back to an early period.
In 1836 F. Schulze showed that no decomposition
occurred in putrescible materials when he boiled them,
thus killing any germs which might be present, and then
prevented the access of air, as for example by inter-
posing a layer of oil, or conducted the entering air
through sulphuric acid, which detained and destroyed

72 FERMENTS AND MICRO-PARASITES.

the germs. Schwann also in 1837 made similar experi-
ments ; he freed the entering air from the organisms by
heating it .strongly. At a later period Schroder and von
Dusch attempted to remove the putrefactive germs from
the air by simple mechanical means, for example by
filtering the air through cotton wool; this was com-
pletely successful, and no putrefaction occurred in
vessels containing boiled putrescible materials and
plugged with cotton wool. Hoffmann, and later Chev-
reuil, and in 1862 Pasteur obtained the same result by
drawing out the neck of the flask used for the experi-
ment, and bending it several times acutely.

The weight of all these experiments was much
enhanced by the fact that control experiments were
made in which the same fermentescible fluids were
employed, and treated in the same way (by prolonged
boiling, &c.)i only with this difference, that the air
entered the vessels without being previously deprived of
its germs by filtration or by destructive agents. In
these control-experiments fermentation or putrefaction
always occurred ; and the same result was obtained if
the protective arrangements were subsequently removed
from vessels which had been preserved free from germs
for a long time, and the entrance of germ-laden air
was permitted, or when germs were intentionally sown
from other putrefying fluids.

These experiments were repeated later on a gigantic
scale in the preservation of articles of food ; scarcely any
biological experiment has been so extensively carried out,
and has furnished such a uniform result. If fermen-
tescible substances are treated by methods which are able
to destroy existing organised germs, and if the entering
air, and everything that will eventually come in contact
with these substances, is treated in such a way that no
organised living germs can enter, neither fermentation
nor putrefaction occurs ; if any of these precautions are
omitted, and the entrance of germs is allowed, then
fermentation takes place. It is true, as may be remarked
here in passing, that at a later period contradiction of
these experiments and their results was not wanting.

GRADUAL DEVELOPMENT OF THE GERM THEORY. 73

Some investigators asserted that in spite of the most
careful isolation of the fermentescible substances, and m
spite of the most thorough destruction of existing germs,
putrefaction and fermentation nevertheless occurred.
These experiments will he discussed helow, hut I may
here point out that a contradictory result must be
obtained when even one of the many necessary precau-
tions is omitted during the experiment, and that
therefore a certain percentage of unsuccessful attempts
at preservation is something quite intelligible.

The more experienced the experimenter, the more
rarely do the experiments fail ; the more the methods of
preserving food have been developed, so much the more
successful are the results. The best experimenter must
register a series of failures when he begins to busy him-
self with these questions, in which the sources of error
are so numerous, and in which unusual precautions are
required. But for this very reason a few of these con-
tradictory experiments, in which putrefaction and fermen-
tation occurred, in spite of the apparently complete
exclusion of all germs, cannot be used as a proof against
the vitalistic theory.

If we assume, for the present, that the result of the
most numerous and carefully conducted of these experi-
ments is that by the exclusion of organisms putrefaction
and fermentation are prevented in fermentescible sub-
stances, there at once arises another old matter of dis-
pute, namely, that with regard to abiogenesis (generatio
(equivoca). Seeing that no development of organisms
occurs in substances which under ordinary conditions
offer a most admirable soil for their development, when
the access of living organisms is rendered impossible,
and seeing that the most active life at once appears as
soon as even the smallest number of living organisms
enters, tha conclusion is justified that the living cells
cannot be formed from unorganised material, but that
they always originate from another organised cell.

The experiments referred to admitted, however, of
two valid objections, and hence they required to be
further modified if they were to prove absolutely the

74 FERMENTS AND MICRO-PARASITES.

vitalistic theory of fermentation, or the improbability of
abiogenesis. Thus a possible objection to some of the
experiments was that the deficiency of oxygen in the
boiled and hermetically sealed vessels hindered the
development of organic life; but this objection was
already met by the fact that the experiments with air
filtered through cotton wool permitted an undiminished
supply of oxygen, and that nevertheless the develop-
ment of organisms was prevented. It was much more
difficult to answer the other objection; it was said that
the heating of the fermentescible substances which were
employed for the experiments altered them in such a
way that so-called chemical ferments which were pre-
viously present, and were able to cause their decom-
position without the intervention of organisms, were
destroyed by the heat, and that it was for this reason
that decomposition did not occur. Had the heating
not taken place these substances would have undergone
fermentation under the influence of those ferments even
without the entrance of organisms. The advocates of
spontaneous generation also put forward a similar plea,
assuming that as the result of the action of the heat an
alteration of the material occurred, and that it thus
became unsuitable for the generation of cells. These
objections gave rise to a large number of new experi-
ments with unboiled and quite unaltered organic
materials. Van der Broek, Pasteur, Bindfleisch, Lister,
and many others, more recently Meissner, Leube,
Hauser, Marchand, Cheyne, were able to preserve for
years a great variety of fermentescible substances with-
out the occurrence of any fermentation or putrefaction
if only they were not previously exposed to the danger
of contamination by organisms, and were protected
from the entrance of new germs and kept in absolutely
pure vessels. In this way success was obtained with
grape juice, yolk of egg, blood, milk, the most various
animal organs, £c. These experiments, which we must
discuss more fully at a later period, and as compared
with which a few experiments in which the attempt to
preserve materials by the same method failed have of

GRADUAL DEVELOPMENT OF THE GERM THEORY. 75

course no value, are of the greatest importance for the
questions of abiogenesis, and of the role of the
organisms in fermentation and putrefaction. It was
only as the result of these experiments that it could be
absolutely maintained that spontaneous generation does
not take place, and that fermentation and putrefaction
do not occur without the aid of minute organisms.

3. If organisms are the constant cause of fermentation 3. Fermenta-

T /.,• i • i ,1 t> , tive organisms

and putreiaction, one must, bearing m mind tne tact occur every-
that decomposition of putrescible materials occurs at all ta^feraient-
places and at all times (provided that no special means escible sub-

Sl&HCGS

are employed to prevent it), come to the conclusion that alway
these lower putrefactive organisms are extremely widely
distributed, and that thus there is always and every- provided that
where opportunity for the infection of putrescible organisms are
materials. The further efforts of the advocates of the
vitalistic theory were therefore directed to the demon-
stration of the presence of organised ferments in all oar
surroundings. Investigations which were begun by
Ehrenberg, and then continued by Pouchet, Tyndall,
Pasteur, Cohn, &c., demonstrated with certainty that
the air always contains the germs of fermentation and
putrefaction, that dust consists in part of micro-organ-
isms, and that water, soil, and in fact all our surround-
ings are always contaminated by these minute cells. In
recent times the methods, more especially of aeroscopy,
have been perfected on the view that the air is the most
frequent carrier of the germs, and is the medium which
leads most frequently to the infection of fermentescible
substances. Later investigations (Sanderson, Rind-
fleisch, Cohn, Hiller, Brefeld) have, however, shown that
the air in most places contains relatively few active
germs, and that the active agents of fermentation are
conveyed by solid substances, water, &c., which are
contaminated with germs, more frequently than through
the medium of the air ; but by this alteration in
the views as to the part played by the different media
in setting up fermentation there is no change in the
doctrine of Pansperinism and of the universal distri-
bution of germs in our surroundings.

76 FEEMENTS AND MICRO -PAKASITES,

The causal connection between micro-organisms and
fermentation and putrefaction is definitely demonstrated
by tbe investigations to which we have referred. It
was found that organisms were present in all putrefying
and fermenting substances; the same organisms were
shown to be widely distributed in our surroundings ;
it was demonstrated that without these organisms no
fermentation or putrefaction occurred even when the
fermentescible substances were left otherwise unaltered,
the entrance of the organisms being alone prevented,,
and that these changes only occurred when living germs
had been introduced by contact with the impure
surroundings.

Modeof action But there remained the further question, viz., in what
cells in the way the action of these organisms on the fermentescible
substances was to be explained ; and the further experi-
ments and researches with reference to the etiology of
the process of fermentation were made with the view
of ascertaining whether fermentation and putrefaction
were to be regarded as a vital process, as a manifestation
of the life and activity of the causal organisms, and
what were the intimate changes that took place.

Even shortly after Schwann's discovery definite views
were formed as to the mode of action of the organisms.
Schwann himself asserted that the fermentative process
went on pari passu with the growth of the yeast, and
that fermentation occurred by the yeast plant with-
drawing from the nutritive substratum certain materials
necessary for its growth, and at the same time inducing
the formation of alcohol from the elements which
were of no use for nutrition. The contemporaries of
Schwann expressed views which were similar but on
the whole more speculative, and not sufficiently based
on experiment. The vitalistic theory was in reality first
elaborated by Pasteur. It is true that Pasteur did not
succeed in finding at first a suitable explanation of the
process of fermentation, or one which was permanently
adopted; on the contrary, his teaching has undergone
most important modifications in the course of time, and
as the result of further experiments and better know-

GRADUAL DEVELOPMENT OF THE GERM THEORY. 77

ledge; but in such a complicated question, and one
requiring the whole efforts of more than one investigator,
a definite conclusion was not at first possible, and too
rigid a deduction would only have impeded the develop-
ment of knowledge.

In 1857 Pasteur demonstrated that fermentation was Pasteur's
most intimately bound up with the life and the growth T1
of the yeast cells, and was thus a result of the action of
these cells. The growth of the yeast takes place at the
expense of the constituents of the fermentescible fluid,
and therefore all the sugar cannot be broken up into
alcohol and carbonic acid ; on the contrary a portion
(about 5 per cent.) is employed for building up the cell
constituents and for the formation of bye-products.
The fermentescible materials form the nutriment of the1
yeast, and these cells employ a portion for the formation
of new cell substance, while the other and much larger
portion is transformed in the yeast cell into alcohol and
carbonic acid. As the yeast cells consist also of nitro-
genous material and mineral substances Pasteur assumed
that traces of both these materials must be present in
the fermentescible fluids if the yeast was to develop and
break up the sugar. Pasteur found at a later period
that 3'east could develop in pure sugar solutions free
from nitrogenous materials, and could there excite fer-
mentation ; but the further development in this case
takes place at the expense of a reserve stock of nitro-
genous material which fresh yeast cells usually contain;
In like manner old dead yeast cells seem to be able to
furnish new nutritive material for young cells ; and
under certain circumstances, namely, when yeast is
mixed with fluid free from sugar, the non-nitrogenous
substance (cellulose ?) of the old yeast cells can take the
place of the sugar, produce alcohol and carbonic acid,
and so give rise to a fermentation of the yeast itself.

In the year 1860 Pasteur showed that it was not
essential that the nitrogenous nutriment of the yeast
should consist of albuminous materials, but that salts
of ammonia could take their place. Such salts along
with mineral substances (which are most easily added in

78 FERMENTS AND MICRO-PARASITES.

the form of ashes of yeast) and sugar form the only
necessary ingredients for a cultivating fluid for yeast,
and in solutions of this simple composition fermentation
goes on well. These experiments were completely con-
firmed by Cohn, Duclaux, &c., and they render it quite
impossible to ascribe to the albuminous materials in the
fermenting fluids such an important role in the fermen-
tative process as Liebig, for example, has done. (See
below.)

The following observations on its relation to oxygen
were also very important for the knowledge of the tissue
change of the yeast. Pasteur found that the fermentative
organisms during their growth took up a large quantity
of oxygen and gave off carbonic acid ; this fact was con-
firmed by Schiitzenberger, who further ascertained that
the more oxygen was used the more active was the
vegetation of the yeast cells. Several other investiga-
tions led to similar results (Traube, Brefeld), and
thereby the biological behaviour of the fermentative
organisms seemed to have been made clearer and the
direct dependence of fermentation on the nutritive
processes of yeast rendered more certain.

But further investigations by Pasteur led to very
different results. He found that if the access of air
were hindered alcohol was formed in large amount,
while if oxygen was admitted but little sugar was broken
up. Pasteur made the same observation in the case of
other fermentative processes, for example in butyric
fermentation and in putrefaction ; active fermentation
only occurred where the amount of oxygen was deficient ;
the admission of oxygen seemed in fact to be detri-
mental to the fermentative processes, although growth
and multiplication of the yeast cells could take place.
Certain exciting agents of fermentation and putrefaction
did not however seem to be able to exist without free
oxygen ; Pasteur distinguished these organisms as
aerobes from the anaerobes which are killed by free
oxygen, or at any rate are active only in the absence of
oxygen.

Deficiency of oxygen seemed to Pustear to be the

GRADUAL DEVELOPMENT OF THE GERM THEORY. 79

most necessary condition of fermentation ; lie looked on
it as practically an indispensable condition for every
fermentation, and formulated his views by saying that
fermentation occurred as soon as any living cell was
compelled to grow in the absence of oxygen, and that
wherever fermentation was found there also the oxygen
was deficient. More especially in the case of the
alcoholic fermentation Pasteur assumed that the yeast
cells, owing to the deficiency of oxygen, took it from the
sugar molecule, and thus caused the latter to break up.

Numerous later investigations have shown that
Pasteur's results are only in part correct; the majority of
fermentative organisms can, it is true, live and grow with-
out free oxygen, and it is especially those organisms which
can exist without oxygen which possess the property of
exciting fermentation. But, and in this the more recent
views differ somewhat from Pasteur's, these organisms
are as a rule also able to thrive when oxygen is admitted,
destruction or hampering of their development by
oxygen only rarely happens, and the vegetative life and
the fermentative action of the most typical fermentative
organisms occurs most actively in the presence of
oxygen.

Pasteur's view as to the more exact manner in which
decomposition of the fermentescible materials by the
micro-organisms takes place has not, therefore, held its
ground, and other investigators have only as yet been
able to suggest more or less probable hypotheses as to
the nature of the physiological process of fermentation,
and none of these views can be looked on as free from
objection. (Compare the remarks in the fourth part.)
But the numerous experiments which have been under-
taken as proof of the one or the other hypothesis have
always shown that the most intimate relations exist
between the living micro-organisms and the ferment-
ations, and that fermentation must undoubtedly be
looked on as a physiological act of the micro-organisms.
In favour of this view we have, besides the numerous
experiments of Schwann and his followers, the fact that ^
the intensity of the fermentation runs parallel with the yeast cells

80 FERMENTS AND MICRO-PARASITES.

development' of the micro-organisms in the fermenting
mixture, that the fermentations go on best at that tem-
perature which corresponds with the optimum of tem-
perature for the growth and the other vital functions of
the micro-organisms, and that the typical physiological
poisons, such as chloroform, ether, and hydrocyanic acid,
are able even in small doses to prevent the ferment-
ation. It has also been demonstrated by accurate
chemical analysis of the products of fermentation, that
the breaking up of the fermenting material during
fermentation implies such a profound transformation
of the molecules, and such an intense displacement of the
atoms, that an approximately similar alteration could
only be obtained by our strongest chemical agents. And
as such chemical means do not come into play, we are
thrown back on the physiological actions, the profound
effects of which are everywhere evident.

Specific excit- Of greater importance for the further develop -
fermentation, ment of the vitalistic theory of fermentation was
the demonstration of the fact that different sorts of
micro-organisms gave rise to diverse and specific
actions. At the time when the germ theory was
founded, one only spoke of organised ferments in
general. The course and the products of fermentation
and putrefaction were studied under varying conditions,
without paying special attention to the species of fer-
mentative agents present, and without ascertaining
whether one definite species alone, or a mixture of
different fungi, were concerned in the decomposition of
the fermentescible materials. And yet rigid observation
of this kind was absolutely necessary in order to learn
accurately the conditions of the life of the organisms,
and the relation between their life and nutritive pro-
cesses and the phenomena of fermentation. In this
" direction also Pasteur's researches formed the real
foundation. He distinguished with striking perspicuity
a definite form of micro-organism which set up lactic
acid fermentation, another which furnished butyric
acid, &c., and he laid stress on the necessity for further
differentiation. It was thus that the advantages of

OBJECTIONS TO THE GERM THEORY. 81

experimenting with pure cultures of the fermentative
organisms were understood, and by the help of the
results so obtained a more accurate knowledge of the
products of fermentation and of the equation according
to which the material was broken up in the individual
fermentations was gained. These questions even now
form the subject of the most active discussion and work,
and it seems as if, by the aid of the most recent and
important improvements in the methods of pure culti-
vation of the micro-organisms, we may arrive at a pre-
cise knowledge of the different fermentative processes,
such as Pasteur and numerous other supporters of the
germ theory have striven for a long time to obtain.

Objections to the Germ Theory.

In what has gone before, the vitalistic theory has
been represented as a completed whole, of which the
development seemed to be steady, and with scarcely a
trace of fundamental objections and attacks. This, Objections to
however, has by no means been the case ; on the contrary,
from an early period adversaries of the new teaching
have appeared, have laid] bare with much acuteness all
its weak points, and have sought to upset the propositions
of Pasteur and his followers by numerous experiments.

The following were the chief objections : —

1. Various observers found that fermentation and i: Fermenta-
putrefaction occurred in numerous experiments, even
when the entrance of micro-organisms was completely ^GT™ °f
prevented. In the interior of dead bodies, in the contents organisms.
of hatched but uninjured hens' eggs, in dead embryos of
man and animals, intense putrefaction was often present.
Under similar conditions lactic, acetic, and butyric fer-
mentations were also repeatedly observed (Colin, Billroth,
Hiller, Schroder, Hoppe-Seyler, Kuhne). Numerous
experiments were also made by Hoppe-Seyler, Billroth,
Tiegel, Servel, Paschutin, Sanderson, Nencki, and others,
in which putrescible materials were kept for a long time
with such precautions that entrance of organisms ap-
parently could not occur ; nevertheless, in many cases,

' 6

82 FERMENTS AND MICRO -PARASITES.

putrefaction was observed. In the same way in urine,
kept with certain precautions, an alkaline reaction and
commencing putrefaction were observed after some time
(Colin, Billroth, Hiller, &c.)» Attempts were also
made to kill the organisms by the action of heat (Bastian,
Huizinga, &c.), or by the addition of a moderate amount
of carbolic acid (e.g., urine 0'5 per cent. — Hoppe-Seyler).
Nevertheless putrefaction sometimes occurred. Finally,
attempts were made to remove the organisms from
putrefying or fermenting fluids by filtration ; but here,
also, putrefaction or fermentation of the fluid thus
filtered, and free from organisms, occurred in several
cases (Helmholtz 1843, Fleck, and others).

In all these cases when the putrid fluids were ulti-
mately examined the observers found either no trace of
organisms, in which case the fermentation could only
have occurred under the influence of chemical ferments,
the existence and activity of which would lower the role
of the micro-organisms to a subordinate position ; or in
spite of all the precautions against the entrance of
organisms, they were found in the putrid substrata, and
then the supporters of abiogenesis saw therein a new
proof of the accuracy of their views. Even in quite
recent times Bechamp and Wigand have supported with
the greatest energy, and after many experiments, the
theory of the spontaneous generation of minute organ-
isms from the dying cell-protoplasm of higher organic
beings. They observed the origin of moving and
multiplying micro-organisms from the minutest consti-
tuents of dead animal and vegetable cells, and when all
external germs had apparently been completely excluded,
putrefaction and fermentation occurred under the influ-
ence of these organisms.

Sources of In spite of the large number of observers and

e"eriment8S° experiments, the germ theory is however not in any
way upset by these contradictory results. Sufficient
weight cannot be laid on the fact stated above, that in
these observations and experiments the results which
are unfavourable to the vitalistic theory always coincide
with possible errors of experimentation, or with want of

OBJECTIONS TO THE GERM THEORY. 83

accuracy in the observations. In view of the very wide
distribution of the micro-organisnis, and of their
relatively great resisting power to noxious agents, it is
not easy to devise faultless experiments in which the
entrance of organisms into the fermentescible substances
will be prevented with certainty. It is only recently
that the degree of heat which will kill micro-organisms
in all cases has been accurately determined ; and we can
now assert definitely that the earlier observers admitted
sources of error in that the vessels and utensils employed
were not freed from germs adhering to them by exposure
to a sufficiently high temperature. Those experiments
are of course especially difficult in which exposure to
high temperatures, and in fact any alteration of the
fermentescible material, must be avoided, in order not to
interfere with any possible abiogenesis, or with the power
of the chemical ferments. It is only after great practice
and many failures that one is able to carry out such a
series of experiments with uniform results. If one is
contented with a small number of experiments, and is
not completely master of the methods, all or the majority
of his preparations will without doubt contain organisms,
and show putrefaction or fermentation ; and if the sources
of error are overlooked, and if it is believed that in
every case the precautions were sufficient to exclude
micro-organisms, every erroneous experiment will furnish
proof of abiogenesis, or of the occurrence of putrefaction
without organisms. It is clear that it is only possible
to attach weight to such results when they are uniform in
all cases and when we are justified in assuming that the
experimenter possesses the necessary skill in mycological
work. On the contrary, it is known that several investi-
gators— for example, Marchand, Meissner, and others —
have obtained a large number of results which support
the germ theory; substances of a putrescible nature
have been preserved without alteration for years, simply
by absolute exclusion of organisms, and indeed an
increase in the percentage of successes is distinctly
evident in these experiments in proportion to the
increasing skill of the experimenter.

84 FERMENTS AND MICRO -PARASITES.

As the result of more accurate knowledge of the
conditions of the life and death of the lower fungi, it is
at the present time easy to repeat at will the same experi-
ments with similar results, and only he who continues
to hold completely false ideas as to the "biological
peculiarities of the micro-organisms, and who is not
intimately acquainted with the more recent experimental
methods, can at the present day ohtain results which
may be used in proof of the doctrine of ahiogenesis.
The experiments recently published by Wigand have
been made with complete disregard of our present
knowledge. Wigand starts with the view that the dis-
tribution of the micro-organisms, and the danger of
their entrance from without, is not particularly great,
and he does not consider it necessary to test this assump-
tion in the same precise manner as others have done.

The striking result also at which many of the above-
mentioned observers arrived as the result of their
fermentation experiments, viz., that in spite of the
existence of putrefaction or fermentation no organisms
could be found in the fluids in question, rests, as we
can now assert with certainty, on an error. Under
certain circumstances it is a difficult task to recognise
micro-organisms — perhaps degenerated and altered — in
an albuminous fluid which has putrefied for a long time,
and at all events it seems essential to employ in all
cases the special methods which have been recently
.devised, such as drying, staining, &c. ; in former times
these methods were unknown, and as a matter of fact
micro-organisms were not found. But that by no means
justifies us in saying that in reality no organisms were
present at any period of the experiment ; for in more
recent experiments on this point they have never been
missed, if care was taken to examine the fluid at a
sufficiently early stage of putrefaction.

2. Presence of 2. In contrast to the experiments in which putrefaction
found without micro-organisms, it was observed on
other hand that numerous micro-organisms could
without fer- take up their abode in fermentescible substrata, without
mentation. reguiting decomposition, fermentation, or putrefac-

OBJECTIONS TO THE GERM THEORY. 85

tion. Results of this kind were obtained by Hiller, for
example, in his experiments with urine. Further,
living micro-organisms were found by several observers
in organs which had been taken from the freshly killed
animal body, and their presence was therefore pre-
sumably unaccompanied by any alterative action.

These objections and experiments are, however, now
only of historical interest. They date from a period
at which little or nothing was known of the various
species of micro-organisms, and of their very different con-
ditions of life and mode of action. It is now self-evident
that it is not every organism which is able to grow
actively in every nutritive substratum, and further that
the development of certain organisms is not necessarily
accompanied by the formation of stinking gases, in short,
by the ordinary symptoms of putrefaction. To find
organisms without accompanying putrefaction or fer-
mentation is therefore not surprising, and proves nothing
against the vitalistic theory.

3. In several series of experiments it was observed 3. Difficulty in
that albuminous solutions were only slowly or not at all tion of

broken up by the micro-organisms sown in them, that the
latter, in fact, like the higher plants, build up their micro-

,„,,., . T ., organisms.

protoplasm from the simplest organic compounds, and
hence only grow and multiply with difficulty in the living
animal tissue, and in cultivation experiments in eggs,
for example. It was therefore concluded that it was
impossible that they could take any important part in
such intense decomposition of albuminous materials as is
the characteristic of the putrefactive process. (Billroth,
Hiller, Hoppe-Seyler, Paschutiri, and others.)

These observations could only be puzzling at a time
when the marked biological differences between the
different species of fungi were as yet unknown or dis-
regarded. Now we know with the most complete cer-
tainty that some micro-organisms occasion a profound
decomposition of the albuminous molecules, and thus
set up the putrefactive process, while on the other hand
a large number of the lower fungi do not possess any
such power, and therefore we cannot deduce from experi-

86

FERMENTS AND MICRO-PARASITES.

4. Ferment-
by so-called
ferment?

ments with any unknown kind of micro-organisni that
no species is able to cause the putrefactive decomposition
of albumen.

4. More weighty objections, which have held their
ground up to the most recent times, were brought
forward by those investigators who sought a more
directly chemical explanation of the processes of fer-
mentation, and did not regard the vitalistic theory as
clearing up, but on the contrary as obscuring what it
was desired to unravel. Liebig, more especially, and at
a later date Hoppe-Seyler took part in this opposition ;
Colin, Billroth, Hiller, Fleck, and others joined them.

As early as the year 1839 Liebig had endeavoured to
explain the phenomena of fermentation and putrefaction
by assuming the existence in yeast of a soluble proteid
substance, which in breaking up excited the decompo-
sition of the sugar exactly in the same way as numerous
well-known chemical bodies when uniting or breaking
up are able to excite a similar movement of the atoms
in other bodies. This breaking up of the soluble
proteid substances is not an act of the living yeast
cells, but on the contrary is a correlative phenomenon
of their death. It is a peculiarity which may be
noticed in many chemical actions, that relatively small
quantities of the body which is breaking up are able to
set up the decomposition of large quantities of the other
body; thus Liebig instanced the decomposition of
oxalic acid, oxamid, and water in which a small quantity
of oxalic acid is sufficient for a large amount of oxamid ;
he also pointed out the similar fact in the decomposition
of cyanogen by aldehyde in the presence of water. The
difference between the alcoholic fermentation and the
putrefactive process can be easily explained on Liebig's
view. In putrefaction the decomposition is transmitted
by the decomposing albuminous material itself, so that
the process once begun continues by its own movement
even after the original cause which set it going has be-
come inactive ; in fermentation, on the other hand, the
sugar (the substance here undergoing decomposition) is
unable to transmit its own movement, and hence a

OBJECTIONS TO THE GERM THEORY. 87

foreign cause, a ferment, is necessary, not only for the
commencement, but also for the continuance of the
movement.

Liebig's view was, however, evidently a purely hypo-
thetical one ; the decomposing proteid substance which
was supposed to be the cause of the fermentation was by
no means demonstrated to be really present ; the only
experimental support of this supposition was the fact
that in the so-called self-fermentation of yeast which
takes place without the addition of sugar, and entirely
at the cost of the yeast substance, much more alcohol is
formed than could be derived from the amount of
cellulose in the yeast cells, and that thus some other
complex substance contained in the cells must furnish the
materials for the formation of the alcohol. This analy-
tical proof was, however, shown to be erroneous by Nageli
(Theorie der Gcihrung, p. 3), but at a much earlier period
Liebig had been compelled to modify his theory con-
siderably by the numerous experiments which absolutely
proved the direct dependence of the fermentative process
on the life of the yeast cells.

In 1870 he declared that the living yeast cells con- Later
tained and produced the supposed ferment-like substance, S
and that therefore the formation of the ferment depends view
on the life of the cell ; the fermentative act, however, de-
pends on an unorganised ferment, and the yeast cells in
producing the ferment do nothing more than numerous
other cells do. Just as man produces diastatic ferment,
pepsin and trypsin, so all other animals and plants have
their ferments ; but the organisms are not identical with
these ferments, and the fermentative action cannot be
looked on as the direct work of the cells. If it were
possible to separate the ferments from the cells the
latter would then be no longer necessary for the com-
mencement and continuance of the fermentative process.
Similar views were taught by Traube in 1858 ; and in
1876 they were defended by Hoppe-Seyler. They rested
in part on the analogy between the fermentative and putre-
factive process, and the splitting up and decomposition
caused by unorganised ferments. The micro-organisms

88 FERMENTS AND MICRO-PARASITES.

according to this view are not the primary and immediate
cause of the decompositions of organic substances occur-
ring in fermentation and putrefaction ; on the contrary,
it was assumed that a transformation of the fermentescible
materials usually occurs at first from causes present in
the substances themselves — by soluble chemical ferments,
and that it is only when the material has undergone a
certain amount of alteration that multiplication of those
organisms occurs, which on account of the wide distri-
bution of their germs always of course gain access to
these substances ; the nature and constitution of the
fermentescible substrata, and especially the first changes
that occur in it, determine what particular species of
organism chiefly develop and flourish. From that point
these organisms aid as a rule in the decomposition of the
substance ; but they are not absolutely necessary even for
its further splitting up, and the decomposition does not
go on by any means parallel with their development.

On this view accordingly by far the most important
role is ascribed to the unorganised soluble ferments.
Lately we have become acquainted with a large number
of such ferments, and in accordance with this knowledge
the probability of their great activity in the ordinary
processes of fermentation and putrefaction seems to
increase. The action of diastase, of emulsine, of
myrosine, of the inverting ferment of yeast, of ptyalin
and pepsin, the energetic action of the pancreas, and of
the trypsin isolated from it, offered the most important
analogies, and the support of the " chemical" theory of
Differences fermentation. As a matter of fact the supporters of the
action6ofth< germ theory have never disputed the influence and the

ac^on °^ chemical ferments, but an exact analysis of the
the organised decomposition caused by chemical ferments on the one
ageiits^f hand, and of the marked alterations in fermentation
fermentation. and pUtrefaction on the other, lead us of necessity to
the conviction that it is quite inadmissible to designate
these two processes as sufficiently analogous and similar
to warrant the inference that both are due to a similar
cause. The chemical ferments only set up hydrolytic
decompositions ; their place can be taken by so-called

OBJECTIONS TO THE GERM THEORY. 89

contact-substances, and also by dilute sulphuric acid
and various other agents ; the amount of the chemical
ferments remains the same or becomes diminished during
the process ; the best temperature for their action is
about 60° C., and they are not affected by powerful
physiological poisons. In fermentation and putrefaction,
on the other hand, there is always a complex alteration
in the grouping of the atoms, a separation of carbonic
acid, and often of other atomic groups ; the number of
the causal organisms increases in proportion to the
intensity of the fermentation ; they are most active at
a temperature between 25° and 40° C., and their action
ceases under the influence of physiological poisons.
Thus the nature and action of the chemical ferments,
and of the fermentative organisms, are sharply separated
from one another, and a relation between them only
exists in so far as in the more complex fermentative
processes, and especially in putrefaction, both agents
are often at work in such a manner that chemical fer-
ments which are in part produced by the micro-organisms
lead to the solution of the fermentescible substance, and
so prepare the soil for its subsequent profound alteration
under the influence of the specific organised ferments.

If, however, we assume with Liebig that in the latter
instance the transposition of the atoms in fermentation
and putrefaction occurs as the result of the action of a
ferment-like group of atoms which can only be produced
by living micro-organisms, and are practically bound up
with the life of the cells, we cannot regard this view as
an essential objection to the vitalistic theory; it is, on
the contrary, a recognition of it. This view corresponds Recognition o
entirely with the vitalistic theory in the immediate de- t£e0Yrytalistic
pendence of the fermentative process on the life of the
yeast cells ; it only seeks to define more precisely the
mode in which the living cells occasion the decomposition
of the fermenting or putrefying substance. But the exist-
ence of such a ferment is a pure hypothesis, as is evident
from the fact that it has as yet been found impossible to
isolate the supposed ferment from the yeast cells ; this
failure being excused on the idea that the ferment is at

FERMENTS AND MICRO-PARASITES.

once destroyed when the yeast cells die, or even when
their life is interfered with.

As the result of the preceding historical sketch of the
development of the views on fermentation and putrefac-
tion, we may take it as absolutely certain that minute
living organisms are the direct cause of the processes
commonly grouped together under these terms, and
that these processes are intimately dependent on the life
of the organisms.

II. MICRO-ORGANISMS AS PARASITIC EXCITING AGENTS
OF DISEASE.

Even at an early period of scientific observation and
research on the subject of the infective diseases, we meet
with the belief that the immediate cause of these de-
vastating affections is an entity endowed with vital
Earlier hypo- properties, a contagium animatum. This view was
the organised clearly expressed by Hufeland ; but at first all sorts of
fantastic notions as to the more intimate nature and
mode of action of this supposed entity, endowed with
vital properties, were added to these leading ideas. Soon,
however, there was evolved from this cloud of phantasies
the definite view that the transmission of the infective
diseases depended on the growth of independent minute
organisms (Kircher, Linne, Wichmann, and others). In
fact it was extremely tempting to refer the characteristic
phenomena in the occurrence of the infective diseases to
such organisms, and to draw a certain parallel between
these diseases and the processes of fermentation and
putrefaction, which are likewise caused by similar fungi.
The sudden appearance of epidemics in various isolated
places, their relatively slow spread, and the fact that
they often remain localised to a particular locality, must
exclude the idea of an evanescent, gaseous agent. The
mode of their spread, the unlimited development of the
infective material through a large series of individuals,
the transport of the infective material over considerable
distances, its adherence to the most heterogeneous ob-
jects, the stage of incubation, the typical cyclical course

MICRO-ORGANISMS AS EXCITING AGENTS OF DISEASE. 91

of the disease, and the subsequent immunity, pointed
more or less distinctly to the organised nature of the
causal agents, and could be explained by the mode of
development of these supposititious beings. The anxiety
to find a relation between the phenomena of infective
diseases and those of fermentation and putrefaction, is
shown by the fact that by some pathologists the whole
group of infective diseases was designated by the term
" Zymotic diseases."

These views, which have continuously gained ground
during the last forty years, did not, it is true, at first
rest on clear knowledge, and were wanting in an experi-
mental basis. They were only based on speculations ;
but these speculations were made with such acuteness,
and with such logic, that they led to almost the same
results as were arrived at forty years later by elaborate
experimental investigations. It was more especially Henie's

TT, , . ,. * n m • -i • T» 7 T • T deductions.

Henle who, in the year 1840, in his Pathologischen
Untersuchungen, and later, in 1853, in his Handbuck
der rationellen Pathologie, sketched with wonderful pre-
cision the relation of micro-organisms to the infective
diseases, and defined the intimate nature, the vital pro-
perties, and the mode of action of the micro-organisms,
as well as the dependence of the individual phases and
symptoms of the diseases in question on the behaviour of
the parasites, almost as accurately as has subsequently
been done as the result of direct observations with optical
aids, at that time unknown, and of numerous experiments.
The great influence which Henie's views have exercised
on the further development of knowledge on the subject
of the parasitic exciting agents of disease renders it
necessary for us to reproduce at this place some of the
most important of these views in his own words : —

" If we trace the miasmatic contagia in their action on the
animal organism, we find at once, although with many in-
dividual differences, a general and characteristic property
which can only be ascribed to living matter, namely, that of
multiplying at the cost and by the assimilation of foreign
organic material. This conclusion is supported by the course
of the great majority of miasmatic contagious diseases. They

92 FERMENTS AND MICRO-PARASITES.

belong to the group of diseases which I have termed typical,
whose sharply defined stages indicate a development of the
cause in accordance with definite laws, such as we only find
among living beings.

" What was stated above with regard to the properties of
the cause of miasmatic diseases in general holds good as
regards the multiplication of contagia by assimilation. It
can, however, only be absolutely proved in the case of the
inoculable diseases where we are able to define accurately
both the point of entrance and the quantity of material
taken up, and the proof becomes the more insufficient the
more in any given epidemic the number of the cases produced
by miasma exceeds those arising by contagion. That the
cause of the disease has multiplied in the region affected
by the epidemic is probable whenever the latter spreads
gradually from small beginnings and attains large dimensions.

"It is only when its development and reproduction in the
diseased body is demonstrated that we are justified in de-
signating the material which occasions epidemic diseases as
a contagium, and the analogy of these contagia with parasites,
the analogy of the miasmatic contagious diseases with the
results of the deposit of parasitic organisms in living bodies
previously referred to becomes at once evident. This analogy,
as I have indicated above, has led to the discovery of parasites
as the cause of many affections formerly termed contagious
diseases. There are, however, a number of diseases in the
contagium of which nothing has been found which recalls the
forms of known species of animals and plants. Nevertheless,
this negative result is not so certain that we can, therefore,
absolutely refuse to reckon the contagia among these micro-
scopic parasites. It is not necessary to assume that the
organisms which act as contagia are too small for our optical
means. But the smallest animals can only be distinguished
from the cells, nuclei, and granules which occur in so many
tissues and excreta^ especially in pus, by their movements, and
the smallest plants only in certain stages of their develop-
ment by the arrangement of their elementary constituents.
The granules of which the Botrytis bassiana consists behave
exactly like pigment granules or the molecules of pus. It is
possible, therefore, that bodies of very various and of great
significance may be concealed among the molecules which
occur in every microscopical object. It is scarcely necessary
to add that these speculations are as yet only hypothetical,
but they are not superfluous even in the cases where animal
or vegetable parasites have been, or will yet be discovered in
the contagium. The question will, however, still remain,
whether the parasite is an accidental inhabitant of the con-

MICRO-ORGANISMS AS EXCITING AGENTS OF DISEASE. 93

tagium and of the diseased body, or whether it is the important
active constituent. Much has already been gained by these
views which, though they may only represent a transitional
period in our knowledge, will prove a lasting gain. In place
of the unintelligible view that the diseased body, or the
disease itself, forms the contagious material, we have the
opinion that the formation of the contagium is a reproductive
process, and that the disease is the result of the reproduction
of this extraneous being in the organism and at its expense.
From this point of view we must interpret the symptoms of
the miasmatic contagious diseases.

" While we must hold that the cause of the miasmatic con-
tagious diseases is a material endowed with independent life,
which can reproduce itself after the manner of animals and
plants, can increase by assimilation of organic materials, and,
growing parasitically on the infected body, can give rise to
the symptoms of the special disease, yet the question arises
of what the as yet unseen body of this parasite is composed,
the result of whose life is so evident and so devastating. It
is one of the laws of human phantasy that we must ascribe to
the contagium, as soon as we reckon it to be something living,
one of the forms which the known organic world presents to
our senses; hence in the earlier childish times of research
one thought of insects, and when the microscopic animals
were discovered, the infusoria could, with still better grounds,
be accused of being contagium and miasma. At the present
time, since the conclusions that have been arrived at with
regard to the fungus of muscardine and similar diseases, it
seems more likely that the contagium belongs to the vegetable
world, because the extensive distribution, the rapid multipli-
cation, and the tenacity of life of the lower microscopical
vegetable beings, as well as the mode of their action on the
bodies which they have selected as the seat of their vegetation,
present in fact the most remarkable analogies with the infec-
tive material of the miasmatic contagious diseases. Muscar-
dine also arises in stagnant marshes, apparently independently,
as if it were due to miasma ; under the influence of heat and
drought it becomes epidemic and contagious. Towards the
cessation of the epidemic its contagiousness diminishes, and
ultimately becomes lost. Currents of air carry the contagium
over long distances, so that the disease appears again in
another place, under the aspect of a miasmatic affection. The
contagium is an aeriform, and at the same time a fixed, body
It retains its power for years in a dry state. An imponderable
and incommensurable quantity of it is sufficient to set up the
disease, and even to produce devastating epidemics."

94

FERMENTS AND MICRO-PAKASITES.

The earliest

<hscovery of

parasitic ex-

Hauler's
discoveries

Actual facts in support of the theory of the develop-

« ... , . . f-

ment oi disease by micro-organisms were first ob-
tained *>y tne study of a number of diseases of plants
and insects. As far back as 1835 Bassi demonstrated
that a fungus was the cause of muscardine, a fatal
disease of silkworms ; other diseases of insects were
shortly afterwards demonstrated with certainty to be
due to similar fungi ; in like manner Tulasne, de Bary,
and Kiihn explained a number of devastating diseases
of various kinds of grain, of potatoes, &c., by the
entrance and parasitic development of fungi. Also in
the case of the higher animals and man positive proof
was soon obtained that minute vegetable bodies were the
cause of certain diseases. Apart from numerous dis-
coveries of fungi which could not with certainty be
demonstrated to be the cause of the accompanying
diseases, favus, thrush, and various affections of the
skin were shown to be dependent on parasitic micro-
scopic fungi. Of especial importance was the discovery
that anthrax was characterised by the appearance in the
blood of minute rod-shaped organisms, and that these
organisms could be shown experimentally to be the
cause of the disease (Pollender, 1855 ; Davaine, 1863).

On the one hand the constantly increasing frequency
of severe pestilences which led to the earnest desire to
solve the etiological questions, on the other hand the
convincing deductions of Henle, the numerous analogies
with diseases of plants and animals, and the discovery
of the contagium of anthrax, gave rise to a period of
research which was characterised by an excess of zeal
and by a large number of imperfectly proved discoveries
which were of no real advantage to the parasitic theory.

It was Hallier more particularly who became a too
enthusiastic apostle of the parasitic theory. As the
result of numerous researches he asserted that the
various micro-organisms only represented special vege-
tative forms of known mould fungi, arising in conse-
quence of the external conditions of life ; that these
vegetative forms gave rise to all sorts of diseases, but
that under suitable conditions one could always cultivate

MICRO-ORGANISMS AS EXCITING AGENTS OF DISEASE. 95

from them the corresponding mould, and could in this
way demonstrate the true cause of the disease. By the
investigation of and cultivation from a great variety of
diseased organs and excreta Hallier obtained a series of
different fungi which he proclaimed to be the causes of
the diseases ; and in a short time scarlet fever, measles,
as well as cholera, typhoid fever, and all other diseases
of this class, were referred to their supposed cause.

The reaction to this period of fantastical exaggeration Reaction
was inevitable. Authorities on fungi like de Bary yf<?^!
showed that Hallier's investigations were quite value-
less, because they were conducted with totally insufficient
precautions against the entrance of extraneous organ-
isms. De Bary's objections could not be upset, the
structure of Hallier's teaching on parasitic diseases fell,
and at the same time a serious blow was given to the
whole parasitic theory ; even up to the present day
there are those who, as the result of the overthrow of
these errors, look on the development of disease by
micro-organisms as an erroneous and exploded view.

Further positive discoveries with regard to parasites
which have been made by numerous investigators in
recent years tended, however, to restore the lost faith.
These discoveries had chiefly reference to the infective Micro-
diseases of wounds ; Rindfleisch, Waldeyer, and von fn
Recklinghausen (1866, 1870) were the first who directed
attention to the micro-organisms which occurred in
pyaemic processes ; similar Observations were made in
erysipelas, in phlegmon, in diphtheria, and in puerperal
fever (Hiiter, Orth, Oerftel, and others). The pathogenic
nature of the micro-organisms found was confirmed by
numerous experiments on animals (Coze and Feltz,
Davaine, Hiiter, Eberth, Leber, Frisch, Klebs, and
others) .

The striking results of Lister's antiseptic treatment of Lister's
wounds had a most important influence on the recogni- treatment of
tion of the parasitic theory ; carried out with the definite wounds-
aim of preventing or hindering the action of the infective
organisms, and followed by astonishing results, it spread
widely the knowledge and importance of the micro-

96 FEBMENTS AND MICRO-PARASITES.

parasites, and the number of sceptics and opponents
have diminished from year to year. — It is true that the
difficulty of these investigations, which only permitted
an extremely slow advance, and one but little satisfying
to the earnest desire for rapid enlightenment, led some
observers to overstep the limits of exact investigation,
and to attach too far-reaching speculations to the results
of the experiments : it was natural and pardonable that
at times conclusions as to the origin of the diseases
were drawn from the mere presence of micro-organisms
in the dead bodies or in pathological secretions, and
that these organisms were at times prematurely and
erroneously proclaimed to be the exciting agents of the
disease. On the other hand many investigators recog-
nised that it was only by detailed study of the different
forms of micro-organisms which came under observation,
by the investigation of the conditions and results of their
life, by improvement of the methods of microscopical
observation, and by faultless experiments on animals that
a basis could be obtained on which an accurate and sure
insight into the r6le of the parasitic agents of disease
could be founded. Based on the recognition of these
facts the more recent methods of mycological investiga-
tions were built up. Before it was possible to obtain
exact and unequivocal results it was necessary to have
Pasteur's and Cohn's systematic cultivations, Koch's
method of microscopical investigation and pure cultiva-
tion of the fungi, Weigert's and Ehrlich's valuable
researches on the employment of dyes for demonstrating
the micro-organisms, Brefeld's contributions to the
methodical study of the lower fungi, and Nageli's work
as to the conditions of life and the tissue change of the
lower fungi.

The objections which are raised against the parasitic
theory are derived almost entirely from former times,
and are now scarcely heard. Apart from the views of
some stubborn adversaries, who only believe the contra-
dictory results of their own experiments, the doubts raised
against the recent work on tee parasitic theory have to
do chiefly with individual cases and special diseases.

MICRO-ORGANISMS AS EXCITING AGENTS OF DISEASE. 97

Thus from time to time authors have denied that
micro-organisms act as exciting agents of the infective
diseases of wounds, their views being based more espe-
cially on the statements made by several observers,
that after mechanical removal of the organisms from
infective fluids the filtrate, which is devoid of organisms,
exerts pathogenic action. More accurate experiments
have however shown that this action depended solely on
an intoxication, on a poison in solution, and that there-
fore it could not be at all compared with an infective
process (Panum, Hiller, Koch, and others). — The Billroth's ob-
results of Billroth's investigations attracted special at-
tention for a considerable time ; he repeatedly found theory,
micro-organisms in subcutaneous suppurations, where
there was no external wound ; he likewise found them
in living organs; and he concluded, therefore, that
living germs were always present in the body, but that
they were not able to develop in the healthy body, and
could not utilise the tissues of the living body as
nutritive material. It was not till a " phlogogenous
ferment" (Phlogistisches zymoid) had been formed as
the result of decomposition, which ferment could of
itself cause inflammation, that the conditions were
suitable for the development and multiplication of the
micro-organisms ; and under favourable conditions these
organisms can become carriers, and lead to the multi-
plication of this ferment. According to Billroth the
micro-organisms originate from a single plant, the
Coccobacteria septica, which is characterised by the
multiplicity of its vegetative forms, and according to
the external conditions appears now in one, now in
another morphological form.

It is easy at the present time to refute Billroth's
objections. In the first place, we know from numerous
experiments that bacterial germs are not present in the
normal living organism in recognisable numbers, and
that the numerous organisms in the diseased living body
can only be referred to entrance from without — to an
infection. An objection might, however, be made that the
facts made out, as to the absence of pre-existing germs

7

98 FERMENTS AND MICRO-PARASITES.

in animal organs, do not of necessity apply to man, and
it was therefore necessary, when possible, to bring
forward experimental facts which would undoubtedly show
that micro-organisms are the direct and only cause of
certain diseases, and are not merely accidental com-
panions of other noxious materials.
Definite proof Experiments were formerly performed with this aim
tne following manner : inoculations were carried out

micro- with infective substances, an effort being made at the

organisms by - . ,

isolating them same time to free the organisms from other materials

infective ex- adhering to them, which might possibly cause the

periments. disease. In some cases an attempt was made to isolate

the organisms by the addition of distilled water, in

which the organisms would sink to the bottom, or by

filtration ; but in these attempts it was always question-

able whether the noxious materials by possibility present

in solution were really removed, and on the other hand

whether the organisms were not injured by the washing

isolation by and by the great osmosis. Filtration in the living

body, obtained by studying the relation of the foetus to

the infected maternal organism, did not lead to a definite

result, as it was only in certain instances (anthrax) that

the foetus remained free from infection, while in other

cases it also became attacked by the disease.

By dilution of Experiments were then made by dilution of the
matSiaf.tlve infective material, on the assumption — undoubtedly
correct — that only a contagium dependent on a living
organism capable of multiplication could be diluted to
an extreme degree without losing its activity. Such a
dilution was in reality obtained when one animal was
successfully inoculated from an infected one, a third from
the second, and so on through a whole series of animals ;
nevertheless there was always the possible objection in
this case that the cells of the body might take part in
the regeneration of the poison.

On the other hand all doubt as to the pathogenic
properties of certain micro-organisms is removed in the
face of the proof obtained during the last few years, that
the infective material can be diluted outside the body
to an extraordinary extent, without thereby losing its
activity. Thus Koch was able to dilute infective blood

MICRO-ORGANISMS AS EXCITING AGENTS OF DISEASE. 99

to such a degree that one-millionth part of a cubic
centimetre injected into the animal caused the same
typical disease, fatal in eighteen hours, as was obtained
by the injection of undiluted blood. The dilution can,
however, be carried to a much greater extent by the
aid of the methods of cultivation. Pasteur and By cultivation
Klebs were the first to show that micro-organisms, sup-
posed to be pathogenic, could be cultivated outside the
animal body in artificial nutritive material ; that then
after the growth of a cultivation a minimal quantity
could be placed on a new nutrient material, that a trace
of the colonies which then developed could be inoculated
on a third soil, and that thus the micro-organism could
be cultivated through a whole series of generations.
Koch then gave us methods by which it is possible Koch's pure

,-1 ••,. .• /• . . cultivations.

to prepare the cultivations of any given organism
in such a way that no other organism grows along with
it, and that on further transplantations on new soil only
the same organism appears. Thus we could for the
first time study with certainty, and in an unaltered
condition, the organism suspected as the cause of the para-
sitic disease, and that for a long time, and in spite of a
large series of new transplantations. When an organism
has in this way been cultivated through fifty or a hundred
generations, it is self-evident that the last generation
does not contain any of the materials which adhered toj
the original organisms ; it is easy to see that the dilution
must be reckoned by trillions, and must ultimately he-
incalculable ; any poisonous material originally mixed
with it, however intense its action may be, cannot be
present in the last cultivation in appreciable amount, and
therefore when infection is obtained with the last culti-
vation it can only be because the micro-organisms them-
selves, which are constantly reproduced at the expense
of the nutritive materials, are the real noxious agents.

As a matter of fact, inoculations with the minutest
quantity of the hundredth pure cultivation succeed quite
as well as with the original material. In the case of
antbrax, of various forms of septicaemia, of glanders, of
tuberculosis, &c., Koch was able to carry on pure

100 FERMENTS AND MICRO-PARASITES.

cultivations through a long series; if he introduced a
trace of the last cultivation into an animal, the disease
in question appeared with all its characteristic symptoms
after the typical incuhatiou period ; death followed after
a definite time. The results of the autopsy were always
the same ; organisms of the same form, and with the
same characters as those introduced, were found in
enormous numbers in the hlood and tissues ; and traces
of the hlood containing the organisms when inoculated into
other animals, caused in them the same fatal disease.

In the case of these diseases the causal connection of
the micro-organisms was therefore proved with complete
certainty ; and it was natural to draw similar conclusions
with regard to the other numerous infective diseases
which had the same characters. Nevertheless it is best,
and will contribute more to the development of knowledge
with regard to the micro-parasites, if we proceed with the
greatest caution, avoid generalisations, and only proclaim
a disease as parasitic when we succeed in finding micro-
organisms with well-marked morphological character-
istics, in demonstrating their presence in such numbers
and with such a distribution that all the phenomena of
the disease can thereby be explained, in transmitting them
to other higher animals, or if possible in cultivating them
for several generations on an artificial soil, and repro-
ducing the characteristic disease by inoculation of
animals with minute quantities of these cultivations.

That these minute organisms act as parasitic exciting
agents of disease, is as much beyond question as is the
function of similar minute beings in exciting fermenta-
tion and putrefaction. And it is to this fact that the
•great and many-sided importance of micro-organisms
in relation to hygiene and public health is due. It was
the processes of fermentation and putrefaction of organic
substances in our surroundings which first awakened
uneasiness and distrust, and called the efforts of modern
hygiene into being, and the most important, and also
the most difficult part of the hygienic investigation of soil,
water, air, and dwellings, lies in ascertaining those
conditions which favour the development and spread of
the exciting agents of disease.

101

PART II.

MORPHOLOGY AND CLASSIFICATION OF THE MICRO-
ORGANISMS.

The micro-organisms which have as yet been The micro-

., organisms

recognised as exciting agents of fermentation and which interest

putrefaction, or of disease, belong almost entirely ^
to the lower fungi. Certain preliminary observations fungi.
render it probable that organisms which belong to other
classes of plants or animals, for example the algae, the
iiagellata, and the protozoa, may also occasionally act as
parasites, and become of hygienic interest ; but in the
meantime the known facts are too few for a systematic
review of this part of the subject, and it is therefore
sufficient to include here only those micro-organisms
which are of special importance for us, and which
belongto the lower fungi.

In order to indicate the place of the lower fungi in the
system of the plants the following short sketch is given,
and the botanical handbooks, more especially the paper
by Frank on the Cryptogams in Leunis's Botany, and
de Bary's Comparative Morphology and Biology of
the Fungi, will furnish further details.

The fungi, mycetes, belong to the cryptogams, that Place of the
great division of the vegetable kingdom which is vegetable
characterised by propagation by means of spores, in kin?clom-
contrast to the other great division of the phanerogams.
The phanerogams bear flowers and produce seeds, in
which the various parts corresponding to the future
structures of the plants are already distinguishable ;
the cryptogams are flowerless, and propagate by means
of the spores just mentioned, that is to say, by small
cells, which show no differentiation and, when present in
large numbers, resemble one another. The cryptogams

102 CLASSIFICATION OF THE MICRO-ORGANISM? .

are divided into the stem-forming cryptogams, and the
thallophytes, or leafy plants, in which only a leaf or
ihallus is formed, which does not in any way follow the
laws of growth of the higher stem-forming plants.
Former sub- The thallophytes wrere formerly divided into three
SjjjfSJjJ" sub-classes—fungi, algae, and lichens. The fungi
and lichens, were defined as cells devoid of chlorophyll, which can
only obtain nutriment from previously formed organic
compounds, and hence can only live as saprophytes on
organic substances undergoing decomposition, or as para-
sites in living plants and animals. Alga? were described
as cells always containing chlorophyll, which obtained
nutriment from inorganic materials, and for the most part
lived in water. Lichens were defined as a mixture of
cells, some containing chlorophyll and others without it,
which could obtain nutriment from inorganic materials,
and for the most part lived in the air.

Untenabiiity At the present time very little value is attached to
catk)n.elaSSifi" tliese distinctions, which are based chiefly on the pre-
sence or absence of chlorophyll. Even among the
phanerogams there are many plants which are devoid
of chlorophyll (orchids, monotropaceae), but which are
not on that account struck out of the families or orders
to which from their morphological characters they
belong. If also in the case of the thallophytes the chief
stress is laid on the mode of propagation, and on the
morphological characters, the fungi and algae show a
great deal that is common to both. And with regard
to the lichens the latest investigations have shown with
considerable certainty that they consist of a fungus and
an alga, the first of which preys upon the second, so that
they cannot be looked upon as an independent class.
Hence it is best to give up the former division into
fungi, algas, and lichens, and to choose for the whole
of the thallophytes a principle of classification in con-
formity with that employed for the other plants.

Opinions vary greatly as to the most suitable and
natural mode of classifying the thallophytes, but we
need only refer here to de Bary's classification (Vcr-
fflcichende Morphologie und Biologic dcr Pilze, page

GENERAL MORPHOLOGY. 103

142), to Brefeld's subdivision (Untersuchungen ilber
Schimmelpilze, Heft 4), and to Frank's classification
in the third edition of Leunis's Botany, page 398. The
present description will be based chiefly on Frank's
classification, because Leunis's Synopsis is an indis-
pensable book of reference for anyone who studies the
thallophytes minutely.

Among the thallophytes only the fungi are at present
of hygienic interest, hence the algae and lichens are not
at all referred to in the following pages, and with regard
to the forms of algae, morphologically similar to the
fungi, reference must be made to Leunis's Synopsis and
to Colm's Beitrage zur Biologic der Pflanzen, Bd. 1,
H. 2.

From the hygienic standpoint it seems most practical Subdivision of
to depart from the botanical arrangement and divide a practical*01
the fungi into four chief groups, of which the first
comprises the true fungi, or mould fungi ; the second the
mycetozoa ; the third the yeast fungi, or blastomycetes ;
and the fourth the fission fungi, or schizomycetes.

I. THE FUNGI PROPER (MOULD FUNGI).

General Morphology.

The fungi consist of small microscopical cells, in Nature of the
which we can distinguish a membrane and protoplasmic fun°u*
contents. The cell membrane is composed of a sub-
stance similar to cellulose but not identical with it,
and does not show any violet colouration with iodine.
In the protoplasm there are as a rule no nuclei, no
starch granules, and no chlorophyll ; on the other hand
there are frequently vacuoles, oil globules, various
colouring materials, and at times crystals of oxalate of
lime which are however deposited especially on the
outer surface of the cell wall in the form of small
needles and prickles.

The growth of the fungi takes place by elongation of Hypha>.
the cells. Thus a series of threads or hyphae are
formed. Usually the hyphae are divided into segments

104 CLASSIFICATION OF THE MICRO-ORGANISMS.

by transverse divisions ; and the threads are almost always
branched, either by the formation of a branch at some
part or other of a segment, or by the terminal cell
becoming divided dichotomously during growth. The
group of hyphae, whether they are present in small
numbers or quite single, or whether they are united in
masses, is termed the thallus of the fungus.

Varieties of In the thallus we have to distinguish mycelium, and
the mycelium. later fruit.bearing hyphaa. Before the development of
the fruit-bearing hyphae the mycelium is identical with
the thallus, which signifies the more or less diifused
and branched hyphae which have grown on an organic
substratum. As a rule by uniform spread of the
threads in all directions and by continued branching a
flocculent mycelium is produced. At times membranous
parenchymatous layers or fibrous bands are formed by
the close union of numerous hyphae. Under certain
circumstances the mycelium of many fungi assumes the
form of the so-called sclerotia, tuberous fleshy bodies
which develop secondarily from an ordinary mycelium.
In the sclerotium we can distinguish a cortical and a
medullary substance, the latter consisting of interwoven
hyphae, the former of the terminal cells of the hypha)
firmly bound together and surrounded by dark mem-
branes. The sclerotium must be regarded as a resting
form, from which a development of fluid-bearing hyphae
only occurs after a long time, and when the surround-
ings are constantly moist.

The hyphae of the mycelium penetrate with great
energy into the nutritive substratum. In the case of
dead portions of plants the hyphae can bore through
the cell membrane, the molecules of the membrane in
contact with them being broken up. But even in the
case of living plants the parasitic fungi not only spread
on the surface, but the hyphae grow in between the cells
of the plants and send short projections, so-called
haustoria, into the interior of the cells ; or they pene-
trate through the cell walls, as in the case of dead plants.
In like manner animal membranes do not offer any
marked resistance to the penetration of the growing

GENERAL MORPHOLOGY. 105

liyphaB of many fungi, and even teeth and bones may
become infiltrated with fungus threads.

The propagation of the fungi occurs usually by means Varieties of
of spores, i.e., cells, which can give rise to one or several tion.
germinating tubes, and thus to a new vegetative body
similar to the original one. In rare cases some of the
cells of the mycelium themselves form the spores ; as a
rule, however, certain hypha3 grow from the mycelium,
take on another form and show other conditions of
growth, and are termed fruit hypha3, or fruit-bearers. If
a large number of fruit hyphae lie together, a so-called
fruit body is formed, and this is more especially the case
in the higher fungi. The modes in which the spores
develop on the fruit-bearers, and the manner in which
they are distributed after ripening, are very diverse, and
these differences in fructification furnish in the main the
principles on which the usual classification of the fungi
is based.

With regard to the development and dissemination of
the spores we distinguish —

a. Intercalary formation. Along the course of the
growing hyphae certain cells are marked off, assume
a somewhat distinct form, and become spores or spore-
bearing cells. These formations are frequently termed
(jcmmcc.

b. Acrogenous segmentation. The terminal portions
of the fruit hyphae are separated by transverse division,
and act as spores. The thin stalks or fruit-bearers are
termed baMia. If from the ends of these hyphae thin
stalk-like branches proceed, on which the spores are
formed by strangulation, these spore-bearing stalks are
termed sterigmata. As to the mode in which the trans-
verse division of the terminal cells occurs only one spore
may be formed ; or a number of buds may arise at the
same time on the summit of the basidium; or several
spores may be separated one after the other from one
basidium. The freeing of the spores takes place either
by disappearance of the stalk, or by strangulation, where
a zone disappears, or softens in the transverse division
between sporo and fruit-carrier, or by being hurled away.

100 CLASSIFICATION OF THE MICRO -ORGANISMS.

The last mode of separation of the spore, which, is very
peculiar, occurs in this way : the spore cell rests on the
apex of a tube-like basidium, which, in consequence of
continued absorption of water, becomes more and more
turgescent, while it possesses at the same time a very
clastic membrane ; immediately beneath the transverse
division the cohesion of this membrane is less than
elsewhere, and here, therefore, as soon as the turgescence
has reached a certain degree, a ringlike rupture occurs ;
at once the elastic wall contracts, and a large part
of the contained fluid is forcibly driven out of the rent,
and carries the spore with it.

The spores formed by acrogenous segmentation are
termed basidiospores, or acrospores, or simply conidia.
At times this mode of spore formation occurs in fruit
bodies, the so-called spermogonia and pycnida. These
fruit bodies contain a cavity, on the inner wall of which
is a thick layer of basidia which give off numerous spores.

c. Endogenous spore formation. The spores arise in
the interior of mother cells, the walls of which persist
as sporangia till ripening has occurred. The sporangia
are for the most part acrogenous cells ; spore formation
occurs in them by division of the plasma without the
formation of walls. The sporangia have often a club-
shaped or tube- like form, and are then termed asci ; in
these eight ascospores are usually formed. The asci arc
often formed in small round or flask-like fruit bodies, the
perithecia, which enclose a cavity, and the club-shaped
tubes spring from the bottom of this cavitj7.

The ripe spores escape either through an opening in
the sporangium which is formed by sudden and great
swelling of a small circumscribed portion of the wall ;
or the largest and upper portion of the wall of the
sporangium becomes converted into a deliquescent
substance ; or, in the case of the asci, the above-
mentioned ejaculation of the spores is not uncommonly
observed.

d. The spore formation is often preceded by a sort of
sexual fructification. This may consist of the so-
called copulation, in which two hypha?, each with a club-

GENERAL MORPHOLOGY. 107

shaped protrusion, grow towards one another, unite after
absorption of the opposing walls, and form a zygospore.
For the most part, however, well-marked male and female
sexual organs are formed. The female is attached to a
mycelium thread in the form of a glohular swollen cell,
and is termed oogonium ; the male, antheridium, is a
long or club-like swollen cell which attaches itself to the
oogonium and becomes separated from its hypha ; at
times the antheridium sends a so-called fertilising tube
into the interior of the oogonium. After fertilisation,
the oosporcs, which are globular cells provided with a
cellulose membrane, are formed in the oogonium. Such
anastomoses between hyphre do not, however, in all cases
indicate a sexual copulation.

The ripe spores are for the most part simple, often, structure of
however, composite, cells of very varying forms ; usually *
they are spherical or oval ; at times, however, they have
the form of long thin rods. The wall consists of an
external, and often coloured sheath, the episporium, and
an inner, more delicate, colourless layer, the cndosporium.
The contents consist of protoplasm, and oil globules
are frequently present. The general distinctive cha-
racteristic of the spores is that they either become
converted into the mother cells of new spores, sporangia,
or send out one or more germinating tubes from which
the mycelium threads may again develop.

The swarming spores and the resting spores behave
somewhat differently. The former are round, naked pro-
toplasmic bodies without a firm cellulose envelope, pro-
vided with two cilia, and thus capable of movement; they
arise endogenously from the spores by division of the spore
contents, and become free by swelling of the sheath of the
sporangium. They are only formed and liberated under
water. After the mobile, naked stage has lasted for a
short time, the swarming spores come to rest, surround
themselves with a cell wall, and then, like other spores,
send out a germinating tube. By resting spores we
understand those spores which are not able to germinate
immediately after their formation, but require first a
period of rest, e.g., a whole winter. Zygospores and

108

CLASSIFICATION OF THE MICRO-ORGANISMS.

Different
modes of
spore form-
ation in the
same fungus.

oospores are the forms which usually behave as resting
spores.

These different kinds of fructifying organs occur at
times together or in succession on one and the same
thallus ; the same fungus can under certain conditions
furnish hasidiospores, and under other conditions asco-
spores ; thus there is frequently a polymorphism of the
fructifying organs. In addition an alternation of genera-
tion often occurs ; the thallus of one fungus bears only
one form of fructifying organ ; the spores so developed
grow to form a thallus whicfris different from the original
thallus and gives rise to another fructification, often
indeed not growing on the same host, but requiring
another species of plant for its development. From the
spores formed on the second thallus, the original my-
celium with its characteristic fructification is again
developed.

Sketch of the
classification
of the fungi.

Classification of the True Fungi.
(After Frank in Leuriis's Synopsis).

First order : Ascomycetes. — Highly developed form of
fungus ; at the height of vegetation ascospores are
formed. A formation of prot ospores often precedes this
fructification, these bodies appearing in the form of
conidia-carriers and conidia or spermogonia. The
protospore forms of the ascomycetes, such as Eurotium
aspergillus, Erysiphe oidium, &c., which occur much
oftener in nature than the higher forms of fructification,
were formerly described as particular species of fungi,
and have only recently been associated with the ascospore
forms.

Families : PerisporiaceaB, Pyrenomycetes, Tuberaceae,
Discomycetes, Gymnoasci.

Second order: Basidiosporece. — In these the spore
formation always occurs by acrogenous segmentation,
even when the fungi have reached the acme of develop-
ment. Almost all form fructifying bodies, which carry
in their interior a hymenium layer of basidia.

CLASSIFICATION OF THE TRUE FUNGI. 109

Families : Gasteromycetes, Hymenomycetes, Tremel-
lini, ^Ecidiaceae or Uredineae, Entomophtoreae, Ustila-
gineae.

Third order: Zygomycetcs. — These form zygospores,
as the highest form of fructification ; these spores arising
by copulation. A non-sexual formation of spores by
sporangia, or by separation of conidia, usually precedes
this fructification.

Families : Mucorineae, Chaetocladiaceae, Piptocepha-
Iidea3.

Fourth order : Phy corny cetes. — These are unicellular
thallophytes. The cell is tubular, and forms the spores
at the end of some of its branches. In the non-sexual
fructification these spores are swarming spores or conidia;
oospores are also often formed.

Families : Saprolegniaceae, Peronosporeae, Chytri-
diacese.

Of the various orders and families mentioned, I Description of
have only selected for more detailed description those interesting* Y
which are of directly hygienic interest, in that they at fungi-
times appear as parasitic exciting agents of disease in
man and the higher animals ; or those which demand
attention on account of their wide distribution as ordinary
mould fungi, and on account of their constant occurrence
in all practical mycological work. In addition, some of
the forms which attack lower animals and plants are
described shortly where the mode of appearance and
distribution of the diseases excited by them furnish
analogies with human infective diseases. For all other
details the botanical text-books mentioned above must be
consulted.

A. The following forms, which are parasitic on plants
or the lower animals, may be mentioned : —

1. Ustilagineae. The fungi of various forms of blight Blight fungi,
(order : Basidiosporeae). These are parasitic on the
organs of plants, especially on various kinds of grain.
The fine mycelium threads grow between and transversely
through the cells of the plants. At certain spots the

110 CLASSIFICATION OF THE MICRO-ORGANISMS.

hyph» multiply, become segmented, and break up into
spores, which then occupy the place of the tissue destroyed,
in the form of dark, dust-like masses. The short
germinating tube (promycelium) branches in single
segments (sporidia), which become detached from the
promycelium, and can again grow in the form of germina-
ting tubes. Different species of these fungi attack different

parts of the plant,
n now the flower,

now the stalk and

of

Fig. 1.— Ustilago carbo X 400.

A, ripe spores.

, forming promycelium

flower, and now
the root. The
detection of the
disease depends
chiefly on the
presence of the
dark masses of

spores. Continued moisture is necessary for the germi-
nation of the spores, and for the penetration of the
germinating tubes into the host. The disease is pre-
vented by diminution
of the moisture, or by
disinfection of the
grain, e.g., by means
of sulphate of copper.

Ustilago carbo (brand,
smut). — A black powder
on the ears and panicles
of wheat, barley, and oats.
Atthetime of harvest the
brand mass,whichrapidly
breaks up, is removed by
wind and rain, and hence
there is no contamina-
tion of the meal. Spores
brown, spherical (fig. 1);
cpisporium smooth;
sporidia composed of
longish cells (fig. 1, B).
About 30 varieties.

Tilletia, caries (smut).
—A blackish brown
powder in the grains of

Fig. 2.— Tilletia caries X 400.

sp, ripe spores.

PPi sprouting spores, at a commenc-
ing development of the sporidia ;
at s fully formed sporidia united
in pairs.

x, germinating tube of a sporidium.

s1, secondary sporidia.

CLASSIFICATION OF THE TRUE FUNGI.

Ill

wheat and spelt which smells of herring brine. The grains do
not fall to pieces, but remain closed ; hence the brand mass
contaminates the meal, and imparts to it a disagreeable smell.
Spores spherical, pale brown ; episporium, with highly de-
veloped reticular thickenings. When the spores sprout there
is formed at the end of the promycelium a whorl of thread-
like sporidia, which at the lower half become united in pairs
by a transverse branch, and drop off while thus united ; these
send out at some point or other a thread-like germinating
tube, in which there is frequently a separation of secondary
sporidia in the form of longish oval cells, which can again
sprout (fig. 2).

When grown in saccharine solutions the Ustilaginca?, ac-
cording to Brefeld's recent investigations, form a continuous
series of vegetative forms, the promycelium either continuing
to develop in the form of buds, or the germinating tube of the
resting spore growing to form a thread-like mycelium, which
gives rise to spores by segmentation, either in the fluid or
on branches rising into the air.

2. Entomophtorea3 (order: BasidiosporeaB).
organisms grow
parasitically on in-
sects, and cause
the death of their
hosts; they are the
ciuse of certain
epidemic diseases
of insects.

Empusa muses?. —
Parasitic on house
flies. The flies which
are killed by this
fungus hang on the
walls with their legs
extended; three
white belts (the
basidia) project be-
tween the segments
of the swollen pos-
terior part of the
body; the fly is sur-
rounded by a broad
white area of dust,
which consists of
spores which have
been thrown off . The

These Empusa
muscse.

Fig. 3.— Empusa muscae X 30 J.
(AfterBref3ld.)

A, ripe spores surrounded by protoplasm.

B, a portion of the skin of a fly with germi-

nating1 spores.

C, a hypha formed in the interior of the

body, the swollen end of which is do-
veloping into a basidium.
Z>, portion of a similar thread with the spore
already evident

112 CLASSIFICATION OF THE MICRO-ORGANISMS.

spores (O'Oll mm. in diameter) sprout readily on the skin of
the abdomen of healthy flies, send out a germinating tube
which penetrates under the skin and there forms, by budding,
short round cells, which become detached and spread in the
blood (the germinating tube possesses a very sensitive mem-
brane which is at once dissolved in water, but not in salt
solution). These cells ultimately develop into tube-like hyphae,
of which one end projects through the skin of the posterior
part of the body, in the form of a club-like basidium. The
upper end of the basidium then forms spores by the production
of a pocket, into which plasma flows; this pocket, the future
spore grows, and finally becomes cut off by segmentation
from the basidium. Large vacuoles are then formed in the
latter, it takes up more and more moisture, and becomes
swollen; finally it bursts, and the contents spouting out, hurl
away the spore with considerable force. The empty tube
shrinks, and in its place a new one appears, in which the
same process is repeated. In this way the dusty layer of
spores around the flies is formed; the round spores (fig. 3) are
surrounded by a layer of plasma, which favours their adhesion
to the body of other flies. To this group also belong Empusa
radicans, observed in the caterpillars of the common white
butterfly, and Farichium megaspermum in the caterpillars
of Noctua segetum (Winter -saateule).

Fungus of 3. Peronosporeae (order : Phycomycetes). Parasites

on living plants ; the mycelium present between the
cells sometimes sends haustoria into their interior. All
these fungi can fructify asexually, fruit hyphae projecting
from the surface of the plant, and giving rise to conidia by
segmentation. The ripe conidia can at once germinate,
either by the direct formation of a germinating tube, or
by division of their contents into a number of portions,
which grow into swarming spores ; these ultimately
sprout like the other spores. Many peronosporeae,
however, possess in addition a sexual fructification.

Species Peronospora ; about 40 varieties, attacking a num-
ber of phanerogams; mostly on green parts, the conidia
bearers being situated by preference on the under surface of
the leaves. The parts attacked become prematurely yellow
or brown, and die ; the conidia bearers form a fine, grey,
mould-like covering on the surface. Peronospora infestans :
fungus of the potato dis-ease ; mycelial tubes O005 mm. thick,
without haustoria; conidia bearers with 1 — 5 branches, thin
towards the top, with ellipsoid or egg-shaped conidia (fig. 4).

This fungus has been known in Germany since 1830, and
was very destructive between 1845 and 1850; since then it

CLASSIFICATION OF THE TRUE FUNGI.

113

has only been present when there was a large amount of
moisture. From the end of June brown spots appear on the
leaves, the under surface of which shows the mould-like
border of conidia bearers ; this is soon followed by the death
of the plant. Decom-
position of the tubers
then takes place;
dirty brown patches
indicate the develop-
ment of the my-
celium. On the dead
tubers two forms of
mould fungi fre-
quently develop :
Fusisporium solani
and Acrostalagmus
cinnabarinus, which
however have nothing
to do with the disease.
The infective fungus
lives through the
winter in the tubers,
reaches the field with
the seed, and deve-
lops by preference
during extreme
moisture ; it is only
young parts with
delicate membranes
which permit the
entrance of the ger-

Fig. 4. — Peronospora infestans.
(After de Bary.)

A, Young twig of the fungus.

B, Formation of swarming spores.

(7, Swarming spores which have bored through
the epidermis of a potato stalk.

D.

a. The conidia (c) forms a secondary one (s) .

b. Sprouting of conidia.

minating tubes.
Disinfection experi-
ments have as yet been without result; but the local pre-
disposition may be influenced by avoidance of moisture, the
individual predisposition by the selection of resistant, tough-
walled kinds of potatoes, and the seasonal predisposition by
preserving the seed in a dry state and sowing late, a slow deve-
lopment of the fungus and a rapid growth of the potato being
obtained in all these ways. Other kinds of peronospora occur
on leguminous plants — clover, vines, leaves of beet-root, &c.

4. Pyrenomycetes (order : Ascomycetes). They Jive
partly as saprophytes and partly as parasites, on plants or
insects. There are usually two modes of fructification :
conidia and ascospores, the latter formed in perithecia.

Claviceps purpurea, the fungus of ergot, occurs in the fruit

8

114 CLASSIFICATION OF THE MICRO-ORGANISMS.

Fungus of
ergot.

of grasses. The fungus develops in the first place on the bloom,
in the form of a conidia-bearing stroma, which looks like a
dirty white, cheese-like mass (sphacelia, see below). The
numerous conidia project from the bloom, and are covered
Mrith a saccharine sticky juice (honey-dew) secreted by the
fungus. The fungus is spread directly by means of the
conidia; the mycelium becomes gradually converted into a
black sclerotium, which assumes a horn-like form (1 — 3 cm.
long), projects from the bloom, and carries at first on its
apex the dead and dried remains of the mycelium, like
a cap of a dirty yellow colour. This sclerotium lasts during
the winter, germinates in spring on moist soil, and develops

Fig. 5. — Claviceps purptirea.

A, sprouting sclerotium (c) with fruit-bearers (W).

jB, longitudinal section of the upper part of a fruit-bearing hypha ;

cp, perithecia more highly magnified.
C, section through a perithecium ; sh, external layer of tissue ;

hyt network of hyphse ; cp, orifice of perithecium.
7), ascus torn and giving exit to the thread-like spores sp.
J'J, ear of rye with ergot c ; s, remains of the sphacelia.

perithecial-bearing stromata in the form of small stalked red-
dish heads. The perithecia are embedded in the surface of
the head ; the spores are thread-like, unicellular. The sclero-
tium which has the form of a cylindrical, dark violet body
with long sulci, and is in its interior white or reddish, and

CLASSIFICATION OF THE TRUE FUNGI.

115

hard and wax-like, is known as ergot (Secale cornutum). It
occurs most frequently in the bloom of rye, more rarely in
barley and wheat. Damp situations favour its appearance.

To this group belong also Cordyceps isaria; fungi, whose
conidia bearers (isaria) develop parasitically on living larvae
and caterpillars, while the perithecial fructification develops
on the dead animals in the form of club-like stromata (cordy-
ccps). — Also Fumago and pleospora, which are parasitic on
ants, and laboulbenia on insects, but often without any
serious disturbance of health.

Botrytis, grape mould. — Fruit hyphae divided at the apex
into little short closely aggregated branches, on which the
unicellular spores are seated. The proper fructification by
ascospores is unknown in most of the varieties. Mould-like
fungi occurring on putrefying portions of plants, but also
parasitic 011 insects.

Botrytis Bassiana, the muscardine fungus. — As was first Bassi's mus-
recognised by Bassi in the year 1835, this fungus is the cause
of the fatal disease of silkworms, called muscardine or calcino.

Fig. (5. — Botrytis Bassiana. (After de Bary.)

A, spore-bearing portions of the fruit hyphas X 390.

5, spore-bearing twigs, at b most of the conidia have fallen off X 700.

C, fungus threads from the inner part of the skin of a caterpillar,
at c numerous cylindriform conidia are being given off by stran-
gulation X 300.

This disease formerly caused great devastations, but for some
years has almost entirely disappeared. This fungus also
occurs on various indigenous butterfly caterpillars and
insects. It penetrates through the skin into the body, the
germinating tubes pass deeply among the muscular bundles
and fat lobules, where they give off cylindrical conidia from
their sides and apices. These conidia multiply in the blood,
and form a widely distributed mycelium by longitudinal
growth and transverse segmentation. From this mycelium

116 CLASSIFICATION OF THE MICRO-ORGANISMS.

the numerous fruit hyphae grow, clothe the stiff mummy-
like corpse with a snow-white mould, and bear on their sides
several spore capsules, with colourless spherical spores. The :
latter germinate in various nutrient solutions, and are thus
capable of artificial cultivation.

iiust fungi. 5. Uredineae, or ^EcidiaceaB (order: Basidiosporece) .
Parasites on plants. The thread-like mycelium grows
between the cells of the plant which acts as host, and the
organs of fructification which arise under the epidermis
burst through it in the form of small, often reddish
dust-like masses or patches, which consist of closely
packed basidia. In most cases there is well-marked
alternation of generation ; formerly the different fructi-
fying forms were described as distinct species of fungi—
uredo, puccinia, recidium — while at the present time
these former specific names are only used for the
particular spore form of these species of fungi.

As an example we may mention Puccinia graminis,ihe rust
of grain, which occurs on many grasses. It forms on its
mycelium, which grows under the epidermis of the plant, club-
shaped masses of basidia, which give rise to spores by segmen-
tation, break through the epidermis, and set free the spores
in the form of oval cells, in whose protoplasm an orange red
oil is present, and whose episporium is colourless and rough.
These spores, the so-called uredospores, or summer spores,
sprout rapidly, and develop always the same mycelium and
the same fructification during the whole summer. In the
autumn, however, club- shaped spore cells develop on the
basidia, which consist of two superimposed cells with thick,
dark brown membranes, smooth 011 the outside; these so-
called telcutospores, or winter spores, germinate in the
following spring, but the germinating tube does not penetrate
into a plant, but sends out only a few thin branches, at the
end of which roundish, colourless cells are formed by segmen-
tation. The sporidia so formed germinate quickly, not on
grasses, but on the leaves of the barberry bush, through the
epidermis of which the germinating tubes of the sporidia
penetrate. The thallus developed in the barberry is called
^Ecidium bcrberidis ; from it short basidia are developed in
flask-shaped organs (ajcidium flasks, the covering of which
is called peridia), and burst through the epidermis on the
under surface of the leaves. On the basidia long rows of
simple roundish cells are formed, containing reddish-yellow oil
drops. The BBcidinm spores germinate as soon as they arc

CLASSIFICATION OF THE TRUE FUNGI.

11'

ripe, but the germinating tubes only continue to grow when
they can penetrate into the stomata of the leaves of grasses.
Here the original my-
celium, with its uredo-
spores, is then developed,
and thus the peculiar
cycle of development of
this fungus is completed.

Along with the aecidia
another fructifying ap-
paratus, the spermogonia,
always occurs ; these are
small jug-like capsules,
which project by prefer-
ence on the upper surface
of the leaves, and shed
their spores even before
the £ecidia are ripe ; the
germination of these
spores has not yet been
observed.

In some uredineas all
three generations occur

on the same host. In Fig> 7.— Bust of grain,

many rust fungi one or ^> Puccinia graniinis. A portion of the
« ,1 i • £ basidiuni with uredospores ( «/•) and

two of the chief genera- a teleutospore (<) X 390. «•

tions are absent. When they only possess the teleutospore
stage these spores germinate as soon as they are ripe, and com-

TT* _ ^^»/i

Fig-. 8.

A, JScidium berberidis. Section through a thickened portion

of the leaf containing Eecidium flasks (a) and spermogonia (sp.)
At a the under surface of the leaf.

B, section through an aecidium in a young condition.

118 CLASSIFICATION OF THE MICRO-ORGANISMS.

mence the development again ; if only the aecidia exist, the
development begins likewise directly they are ripe, and the
process of germination is similar to that of the teleutospores.
The species of the uredineee are described according to the
teleutospores because these show distinct differences, while
the uredo and aecidium fructification essentially coincide in
all the species. The rust fungi occur extensively on the most
various kinds of phanerogams, on grasses, shrubs, and trees.
Moisture of the ground and of the air favours their develop-
ment. In the case of many rust fungi the actual alternation
of generation is not yet certain, and hence the independence
of many forms as yet reckoned as particular species is doubt-
ful. Where it is known it is often possible to prevent the
infection by preventing the development of one of the stages
of fructification. Thus corn-fields may be protected against
infection with rust by extirpating the barberry bushes in the
neighbourhood on which the a3cidium generation occurs.

B. The following mould fungi, which are interesting
either from their frequent occurrence, or from attacking
at times higher animals, and even man, in the form of
pathogenic parasites, are worthy of note : —

PerisporiacesB. 1. Some forms of the Perisporiaceae (order : Ascomy-
cetes). In the fungi belonging to this family the spore
tubes are formed in the interior of a capsule-like fruit
body, the perithecium ; the latter lias no preformed
opening, but tears open when ripe. The perithecia are
very small round bodies, seldom more than 1 mm. in
size, and commonly immediately surround the mycelium
in large numbers ; their walls are for tlio most part
coloured, and often covered with hairs or hair-like pro-
cesses. In many cases the origin of the perithecium by
sexual fecundation may be demonstrated. In eurotium,
for example, short twigs develop from single mycelium
cells and become twisted like a screw (fig. 9, c) ; this
screw represents the female organ, the ascogonium.
From the lower part of this thread branches then grow
outwards along the side of the screw as far as its end,
and one of the branches and the upper turn of the screw
apply themselves to each other and exchange their con-
tents ; after this fecundation the male branches, the
jollinodia, divide and branph frequently, and thus form
a covering which becomes the wall of the perithecium.

EUROTIUM — ASPERGILLUS. 119

Some observers look on this supposed sexual copulation
as only an unimportant anastomosis of hyphae.

Besides the perithecia many perisporiacese present a
second asexual fructification on the same mycelium ;
simple fruit hyphae are formed which give rise to spores,
or conidia, by fission. This asexual fructification is
extremely widely spread, and very frequently it is the
only form ; it is only the presence of a large amount of
nutriment which predisposes to the formation of peri-
thecia. Thus the most common mould fungi usually
form only the asexual fructification, and their connection
with the perithecial forms is for the most part only
recognised at a later period. Hence the conidia forms
of these fungi were described as particular species, while
from recent researches they can only be looked on as
secondary fructifying forms of the ascomycetes. The
conidia germinate readily immediately after they are ripe,
form a mycelium, and again develop conidia bearers ;
on mycelium arising in this way from conidia, peri-
thecia can also presumably develop under suitable con-
ditions, but this has not as yet been directly observed.
The ascospores are as a rule only -able to germinate
after a period of rest ; in the case of some of them it is
certain that they develop to form a conidia-bearing
mycelium. The most important species are —

Eurolium—afpcrgillus.

We distinguish (after Siebenmann) the so-called true Aspergillus.
aspergilli (Asp. clavatus, fiavus, fumigatus, niger,
ochraceus, albus), and the two eurotium forms proper
(Eurotium aspergillus glaucus and Eurotium repens).
In the former the higher form of fructification is repre-
sented by a form of sclerotium, the formation of which
is completed in two periods. In the first period a rest-
ing fruit (Dauerfrucht) is formed consisting of the
centrally placed ascogonium, which is for the time
being inactive, and the store material originating from >
the carpogonium. This condition persists so long as
the sclerotium is in a dry surrounding. On a moist

120

CLASSIFICATION OF THE MICRO-ORGANISMS.

substratum the second period at once begins ; after
absorption of the store material the ascogonium enlarges
and sends out branches which finally develop into
asci containing spores. In the eurotium forms, on the
other hand, very delicate perithecia .form in the place
of the tough sclerotia, and present the appearance of
refracting clear yellow or sulphur yellow transparent
bodies of the size of a grain of sand with an enveloping
membrane which is very easily crushed.

The sclerotia of the true aspergilli are found in old

Fig. 9. — Aspergillus glaucus. (After de Bary.)

yJ, portion of a mycelium thread (m) with a conidia bearer (c) and a

young Eujotium perithecium (F) X 190.
2?, £', conidia bearer with basidia and conidia. J5, some of the basidia

more highly magnified.

C, ascogon surrounded by the pollinodia.

D, young perithecium cut longitudinally ; w, the future wall ; f, the

store material X 250.

E, an ascus with spores from a perithecium X 600

cultivations (for example on brown bread) arranged in
nests in those places where there is incomplete access
of air, and where therefore conidia bearers do not grow ;
they form granules 0*5— 1'5 mm. in diameter, and of
irregular form. Usually, however, only the conidial

EUHOTIUM— ASPERGILLUS.

121

fructification is met with. Fruit-bearing hyphae, not
branching and 0'3 — 10 mm. in length, arise from a
colourless mycelium consisting of delicate hyphae.
These fruit hyphas are globular at their upper end, or
dilated in the form of club-shaped bladders, on
which thin projections or sterigmata are arranged
radially. It is only in the eurotium forms that the
sterigmata are separated by septa from the bladders of
the fruit-bearers. The sterigmata give off at their
apices a succession of conidia, consisting of round or
somewhat oval cells 1 — 6 //. in diameter. Some asper-
gilli (A. clavatus, flavus, fumigatus) have unbranched
sterigmata; in the other three on the contrary they
are branched. The latter forms are also described as
stcrigmatocystis.

Asp. flavus or flavcscens. — Yellow or greenish
brown masses of fungi.
Conidia yellow or brown
Avith a fine warty surface ;
5 — 7 fju in diameter.
Sclerotia very small,
black. Grows best at
about +28° 0.

Asp. famigatus. —
Greenish, often bluish-
grey masses very like
penicilliurn . Short conidia
bearers, curved forwards
to form a hemispherical
bladder, 8 — 20 //, in
diameter. Closely packed
awl-shaped sterigmata on
the hemispherical cup. Conidia round, smooth, with
single contour, for the most part colourless, 2'5 — 3 //,
in diameter. Sclerotia unknown. Thrives best at 37°
—40° C.

Asp. nif/er. — Dark brown masses. The knob of the
fruit hypha completely spherical. Sterigmata 20 — 100
l*> in length, branched like a hand. Conidia round,
when ripe blackish-brown ; diameter 3 '5 — 5 /u, Sclerotia

Fig. 10.— Aapergillus flavus X 300.
(After Siebenmann.)

122

CLASSIFICATION OF THE MICRO-ORGANISMS.

brownish red, of the size of a rape seed. Best tempera-
ture 34°— 35° C.

Fig. 11.— Aspergillus fumi-

gatus X 300.
(After Siebenmann.)

Asp. ochraceus. —
At first of a flesh colour,
later ochre yellow; sphe-
rical heads ; branched
sterigmata.

Asp. CllbllS. Pure v^nco. »jicueimiH,iiii.;

\V h i t, P in oil t\ n v t o • -^ *ke lower part on the left side
all p a 1 1 S , the sterigmata have been removed
iviomfltn.. artificially.

12.— Aspergillus niger X 300.
(After Siebenmann.)

the left side

branched sterigmata. artificially.

Asp. clavatus. — Greenish; club-shaped bladders on
very long and strong fruit hyphae ; very small conidia.

-ja^/^ft^

Fig. 13.— Eurotium aspergillus
glaucus X 300. (After Sie-
bonmann.)

Fig. 14.— Eurotium repens X 300.
(After Siebenmann.)

The eurotium forms possess mycelium and conidia
bearers like the true aspergilli. The perithecia, the

EUROTIini ASPERGILLUS.

123

formation of which corresponds with the general descrip-
tion given above, appear to the naked eje as brightly
refracting, very small, round granules ^ — j mm. in
diameter, arising from the aerial mycelium, which is of a
sorrel colour in this stage of fructification.

Eurotium aspergillus glaucus. — Bluish-green or
yellowish-green ; heads regularly round. Conidia round,
warty or knobby ; 9 — 15 p, in diameter. It occurs in
fruit juice, moist wood, frequently on damp walls, but
only in very cool places — about 10° — 12° C.

Eurotium rcpens. — At first white, ultimately dark
green ; heads often fringed ; conidia oval, smooth,
colourless or greyish-green, 5 — 8*5 p in largest
diameter. Occurs on preserved fruits, bread, &c. ; the
best temperature is 10°— 15° C.

The aspergilli have of late excited special interest Pathoge
because some of them (Asp. fumigatus, Asp. flavus,
and Asp. niger) are able to grow in the bodies of warm-
blooded animals.

This pathogenic property was first ascertained by Action of
studying the result of the injection of mixtures contain-
ing spores into the blood
stream of animals, es-
pecially of rabbits. When
the number of spores
injected was ver}7 large
the animals died in a few
d ays, and numerou s small
deposits of fungus my-
celium which had de-
veloped from the spores
were found in the in-
ternal organs. If smaller
quantities of spores were
employed, the animals
lived, but if they were
killed after two or three
days a small number of
mycelial deposits were

spores.

Fig. 15. — Microscopical section
from the kidney of a rabbit
killed 36 hours after the
injection of spores. (After
Grawitz.)

found ; at later periods these had disappeared, so that when

124

CLASSIFICATION OF THE MICRO-ORGANISMS.

ill small numbers they were evidently quickly destroyed
and were only able to occasion the death of the animal
when in enormous quantity. The mycelia formed from
the spores are not equally distributed in all the organs.
The kidneys are attacked by preference; then the
cardiac and other muscles ; at times numerous masses
are found in the liver. After the injection of the
spores of Asp. fumigatus there are very peculiar dis-
turbances of equilibrium, the animals lying on one side
with the head placed obliquely, the one cheek looking
upwards, the other downwards ; the eyes are directed
towards the same side. If one attempts to raise the
animals from this position they resume it at once ; if
one places them on the opposite side they remain at
first in this position, but soon assume the old posture
with violent rotatory movements around the long axis.
Lichtheim found that the explanation of these symptoms
was the localisation of the fungi in the membranous
labyrinth.

The success of the infective experiments is most certain
with Asp. fumigatus, and then with Asp. flavus. The
spores of Asp. niger do not appear to have by any means
such an intensely malignant action ; the other species of
aspergillus and eurotium are on the other hand entirely
without effect, even when injected in large quantities.

It is not only by artificial infection that growth
of these aspergillus forms is observed in the animal
body, a natural infection seems to occur not uncommonly.
Mycotic diseases have been known for a long time to
occur in the ear passages of birds ; in these cases
we have to do with the growth of aspergilli. Schiitz
has recently demonstrated by exact experiments that
the spores of these mould fungi can as a matter of fact
set up severe pneumonic affections. If healthy pigeons,
geese, and smaller birds were exposed for only a few
minutes to air containing numerous spores of Asp.
fumigatus the animals died of pneumonia as late as the
fifth day afterwards. Numerous mycelial threads were
then found in the bronchi, and in the cases where the
disease had lasted longest extensive necrosis was present.

EUROTIUM — ASPERGILLUS. 125

An affection of the air passages also occurred when
masses containing spores were swallowed. The pneumo-
nornycosis aspergillina is caused most often by Asp. fumi-
gatus, more rarely by Asp. niger ; the spores of the latter
do not form a luxuriant mycelium, but only germinate
imperfectly, while Asp. fumigatus can even fructify in the
larger bronchi when there is a plentiful supply of free
oxygen to the mycelium. In zoological gardens extensive
epidemics of these mycoses have also been observed.
In the case of mammals also, for example in cows, In mammal.-',
similar conditions have been seen in the lungs, and
aspergillus mycelium has been often observed in human
sputum and in the bronchi of dead bodies. Hence it is
not impossible that the inhalation of similar spores
have also occasionally set up pneumonic affections
in man.

Deposits of aspergilli have been found on two parts in man.
of the surface of the human body. Leber observed,
after abrasion of the cornea by an ear of corn, that an
abundant development of aspergillus mycelium took
place in the cornea accompanied by severe suppurative
keratitis. On inoculation of the spores of the fungus
cultivated pure in an artificial soil, on the cornea or
into the anterior chamber of the eye of rabbits, growth
of the fungus occurred. Further, the aspergilli develop
not uncommonly in the external auditory meatus ;
nevertheless only when diseased conditions are already
present, such as perforation of the tympanic membrane
with degeneration of the wall of the tympanic cavity,
and when there is a layer of serum which can act as a
suitable nutritive substratum. In that situation suppu-
rative and putrefactive processes interfere with the deve-
lopment of the aspergilli, while the use of astringent
remedies as a rule favours it ; the introduction of oil
readily sets up eczema, and thus favours the growth of
the fungus, or at any rate of the mycelium, while the
formation of conidia is hindered.

It is noteworthy that it is only those aspergilli whose Temperature
temperature optimum is high and approaches the body iSfe™™0**11
temperature, that can grow in the bodies of warm-blooded aspergilli.

126 CLASSIFICATION OF THE MICRO-ORGANISMS.

animals. Friinkel* was unable to diminish their patho-
genic properties hy the continued action of abnormally
high temperatures. He cultivated Aspergillus fumigatus
for half a year at 51° C., numerous re-inoculations
being made; under these circumstances the fungus
formed only a sterile mycelium, and it was necessary to
continue the cultivations from this mycelium. When
however it was placed at a temperature of 37° C., the
fungus at once began again to fructify, and the spores
formed proved to be as virulent as others cultivated
Distribution in the ordinary manner. — All these fungi appear to
agpergiUi. be very widely distributed in our climate. According
to Siebenmann, it is only necessary to expose freshly
baked brown bread to the air for a short time, to place it
then in a moist chamber and to regulate the temperature at
various heights ; according to the temperature, it is found
that either on the surface or in the interior of the piece
of bread one or other form of aspergillus has developed.

Erysiphe oidium.

Erysiphe forms the mould-like covering on living
plants which is known as mildew. Summer and winter
spores are developed ; the former have the appearance of
oval unicellular conidia which are formed by segmenta-
tion on single upright fruit hyphffl ; the winter spores
are formed in the perithecia which arise at a late period
on the same mycelium, and they are only able to ger-
minate after a period of repose. The fructification by
conidia was formerly described as a separate species of
fungus under the name oidium. In the case of some
forms of oidium the corresponding perithecial fructifi-
cation has not yet been found. Mildew attacks the
most various kinds of plants, and the different species of
plants have their particular forms of mildew. The plants
which are attacked droop and die early. Damp weather
in the latter part of summer and autumn and moist
situations are favouring conditions.

Two important kinds of oidium whose perithecia are
as yet unknown belong to this group.

* Deutsche rued. Wochenschrift, 1885, No. 31.

EEYSIPHE 01DIUM.

127

\

Oidium Tuckeri, the fungus of vine disease. — A whitish
mildewy layer appears on brownish patches of the leaves and
twigs of the vine, and also attacks the young berries, whose
epidermis dies and bursts. The ^

longish round conidia are placed
singly on the fruit hyphae.

Oidium lactis. — Fruit hypha3,
single, upright, colourless ; form a
terminal chain of spores; at times
apparent formation of branches, the
fruit hyphae growing upwards along-
side the terminal chain of spores
already formed. Spores short, cy-
lindriform, 0'0077— O'OIOS mm. long
(fig. 16). Very widely distributed,
forming a whitish mouldy coating
on milk, bread, dung, &c. Flourishes
best between 19° and 33° C. (Hausen).

In some parasitic skin affections
of man development of fungi lias
been for a long time observed,
and these fungi appear to have a
certain resemblance to the my-
celium and fructification of oidium.
Grawitz has in fact attempted to
prove by cultivations that the favus
fungus (Acliorion Schonleinii), the
fungus of Tinea tonsurans (Trico-
pbyton tonsurans), and the fungus
cf Pityriasis versicolor (Micros-
poron furfur) are identical with Oi-
dium lactis. According to Grawitz
the conidia of this fungus, when cul-
tivated artificially, form one or
several germinating tubes ; these
soon become segmented and send
out lateral branches which elong- Fig. l6.-0idium lactis.
ate by apical growth. The growth ^, older, B younger, fruit
ceases often after a very short,
often again after a longer time, and
segmentation of the threads into
conidia begins ; these conidia are
at first almost cubical cells, but later assume a lonoish ovi

Oidium as tho
cause of Favus
and Tinea
tonsurans.

hyphas.
s, chains of spores in the
neighbourhood of which
the fruit hyphas (h) con-
tinue to grow like a la-
teral branch. X 200.

128

CLASSIFICATION OF THE MICRO-ORGANISMS.

form by rounding off of the borders. Certain threads
give off lateral branches almost at right angles ; where
the growth is luxuriant, certain of the lateral branches
become large refracting globes, which are cut off, ai:d
are again capable of growth. The mycelium of the

Fig. 17.— Favus and Tinea fungus. (After Grawitz.)

A. gf rminating tube cultivated in gelatine solution.

11, breaking up of a germinating tube into sirgle conidia (in con-
centrated solution).

C, formation of fruit ; « formation of buds ; b, formation of gemmae.

/>, tinea fungus ; mj'celial threads with fructification.

E, conidia of Oidium lactis (in dilute acid nutrient solution, from
which thin germinating tubes are growing out) X 350.

tinea fungus, &c., is very delicate in comparison with
the much thicker conidia of the Oidium lactis growing
on milk ; but on alteration of the nutrient substratum
Grawitz was able to obtain great varieties in this respect,
^o that, for example, a large conidia sent out a much

ERYSIPHE 01DIUM. 129

more delicate thread, which then gave off a cell of one-
fourth of the diameter of the original one.

Grawitz's experiments were performed at a time when
there were no trustworthy methods of isolating individual
fungi from a mixture of organisms, such as are usually pre-
sent 011 the affected skin, and hence they urgently require
repetition with better methods, and the asserted identity is
rendered very doubtful by the result of experiments made
with other mould fungi. Oidium lactis flourishes only com-
paratively imperfectly at the body temperature, and therefore
its parasitic existence on the surface of the body is improbable.

In the lower animals affections occur very similar to Fungus of
favus in man, and in these the causal agent has of late
been cultivated pure. Such are the fungus of tinea galli
and that of the so-called favus of mice. The first has
been studied by Schiitz ; it leads to the formation of
whitish grey round patches on the comb and wattles of
fowls, which gradually merge together and spread on to
the neck, breast, and trunk. By continued cultivation
on nutrient jelly Schiitz succeeded in obtaining pure
from the scales on diseased combs a fungus which forms
a white mycelium, gradually liquefies the gelatine and
causes it to assume a reddish colour. It grows also
on potatoes, bread paste, &c., and best at a tempera-
ture of about 30° C. Microscopically the mycelium
consists of segmented and often branched threads of very
various dimensions ; not uncommonly these threads
show small warty or pedunculated projections ; some of
the segments are also globular, while others are lying free,
and occasionally provided with processes. Again, in some
cases fine shoots are seen on the sides of the rnycelial
threads, these shoots bearing one or two globular
greyish coloured bodies. Whether these or the spherical
bodies, or neither of them, are to be regarded as spores
is as yet uncertain ; the position of the fungus is there-
fore doubtful, and it is only the microscopical similarity
of the mycelium and the simple separation of the cells
supposed to be spores that has led to its provisional
inclusion among the forms of oi'dium. Inoculation of
pure cultivations of the fungus gave rise to the charac-

9

180 CLASSIFICATION OF THE MICRO-ORGANISMS.

teristic morbid symptoms in fowls; mice, rabbits, and
various other animals were not affected.

Mouse favus has been repeatedly studied, and quite
recently in the author's laboratory. Nicolaier demon-
strated that the disease could be transmitted by the appli-
cation of scales to patches of the skin of healthy mice
previously scraped with a knife and denuded of epider-
mis. After about eight days a crust is formed about
the size of a lentil, whitish yellow, and pitted in the
middle; this crust constantly enlarges till it finally
comes to occupy the whole forehead and ears, spreads over
the eyes and covers the head of the animal with a

Fig. 18.— Cultivation of Mouse Favus.
«, mycelial threads X 300 ; b, a thread more highly magnified X 700,

whitish grey dry mass of a laminated character which
forms a thick layer on the skin. Small crusts planted
on acid nutrient agar, or on potatoes impregnated with
tartaric acid, and kept at 30°— 35° C., give rise after
repeated recultivations to a pure cultivation of a fungus
which forms a thick low mycelium, at first of a pure white
colour, with very closely packed, delicate hyphse, so that
the whole mass (particularly on potatoes) looks like a
crust of sugar. At a later period the surface of the
mycelium assumes a red or reddish-brown colour. In
microscopical preparations of the favus crusts, or of cul-

ERYSIPHE OlDIUiT. 131

tivations, we see a maze of jointed threads which are
terminated by oval cells somewhat flask-shaped, or in
some cases more spherical.

Special spore-bearing hyphae or distinct spore forma-
tion have not as jet been observed. Inoculation of mice
with small quantities of cultivations carried through a
considerable number of tubes gave rise in all cases to the
peculiar disease just described; inoculation of a cock
was tried without result.

Cultivations made from human favus furnished
appearances on the whole microscopically and macro -
scopically similar, but not identical ; the investigations
on this point are not yet concluded. All these three
fungi probably belong to one species, and are in some
respects closely allied to the oidium fungi, but they
appear to differ among themselves as well as from the
Oidium lactis, as shown, for example, by the differences
in their temperature optima.

The fungus of thrush was formerly described under the
name of Oidium albicaiis, and placed among these fungi.
Recent investigations render it, however, probable that the
thrush fungus belongs to the yeast fungi.

2. Mucorineae (order : Zygomycetes). Very widely
distributed ; on putrefying substances they form white
or brown patches of mould, which consist of delicate
mycelium and fruit hyphae given off at right angles.
At the apex of the latter a globular sporangium is
formed, the protoplasm of which breaks up into a large
number of spores. The membrane of the sporangium is
at first colourless, but later it usually becomes blackish,
and when the sporangium is ripe it dissolves in water.
Many mucorineae form zygospores by the copulation of
two mycelium branches ; there is often also a formation
of gemmae.— Among these we may mention: Mucor Saprophytic
mucedo. Fruit hyphae colourless, simple or branched, forms of
V— 13 cm. long; sporangia yellowish- brown to black ;

182 CLASSIFICATION OF THE MICRO-ORGANISMS.

Fig. 19. — Mucor mucedo.

ripe sporangium.

the same, represented as transparent; e, columella; s, the space

filled with spores,
almost ripe sporangium, the membrane having been removed by

artificial pressure.

fruit hypha with naked columella (c) X 70.
an old mycelium thread which has formed an end cell which has

become converted into a gemma X 350.
spore of Mucor racemosus which has sprouted in a sugar solution.

to a germinating tube, and has formed spherical yeast-like cells

(/•) X 350.

EBYSIPHE 01DIUM. 133

membrane smooth, or closely covered with acicular
cjstals of oxalate of lime (fig. 19). . Longish spores
(0*008 mm. long, 0'0037 mm. broad). Very widely
distributed on all sorts of nitrogenous substances. —
Mucor racemosus, much more delicate fruit hyphse, at
most 1*5 cm. long ; sporangia yellowish to light brown ;
spores roundish. Grows extensively on substances rich
in carbo-hydrates. When the mycelium is old, or when
the spores germinate under water, so-called gemmae or
brood cells (that is to say, pear-shaped swollen spots,
which develop thick membranes and a protoplasm rich
in oil) are formed in the hyphae. — On continued culti-
vation in saccharine fluids the germinating tubes become
constantly shorter, and show yeast-like budding ; the
spherical segments are termed spherical or segmentation
yeast (Kugel- or Gliederhefe). These spherical yeast
cells readily lead to deficiency of oxygen in the nutritive
medium, and can then break up any sugar which is
present into alcohol and carbonic acid — in other words,
set up fermentation. The rising bubbles of carbonic
acid usually however carry the yeast cells to the surface,
where they again form normal mycelium, so that the
setting up of fermentation, and the production of C02,
seem to be the means by which the fungus returns to its
normal conditions of life.

Mucor stolonifer. — Mycelium, with branches rising in arches
and again sinking, and attached by root hairs; sporangia
deep black and warty ; spores brownish, almost spherical,
10 — 20 mikrom. in diameter ; zygospores dark brown.

Further : M. macrocarpus ; M. fusiger ; M. aspergillus ; M.
phycomyces, rare.

M. Melittoplitorus. — Found in the stomach of bees ; colour-
less hyphas, with egg or pear-shaped sporangia ; colourless
elliptical spores.

Lichtheim has recently discovered two new species of Pathogenic

, . , . species of

mucor which exert a pathogenic action : mucor.

M. rkizopodi/ormis. Mycelium at first snow-white,
then mousy grey; mycelial threads colourless;
brownish mycelial branches rise and sink in an arched
manner on the surface of the substratum, giving rise at
the point of contact to short branched rhizoids, with

134 CLASSIFICATION OF THE MICRO-ORGANISMS.

straight pointed branches which run downwards, and
to sporangia bearers which pass upwards, very like M

Fig. 20A. — Mucor rhizopodiformis. (After Lichtheim.)
Zeiss A, eye-piece 5.

stolonifer, but
with shorter
sporangial stalks;
the egg - shaped
columella is
arched forwards
in a dome -like
manner, and di-
minishes in size
towards its base ;
spores colourless,
and only 5 — 6 p
in diameter.
M. corymbifer. —

Fig. 20s. — Mucor rhizopodiformis after Mycelium whitish
rupture of the membrane of the sporan-
gium. (After Lichtheim.) g*&J \ Sporangia

Zeiss E, eye-piece 2. bearers not pass-

ing upwards at right angles, but stretched lengthways,
branched in an umbelliferous manner, and forming at
the end of the branches a number of grape-like, um-
belliferous, closely packed sporangia; the latter are
also colourless when ripe, rounded off at their apex,
jointed, top-shaped and gradually narrowing as they pass

ERYSIPHE 01DIUM.

135

Fig. 21 A.— Mucor corymbifer. (After Lichtheim.)
Zeiss C, eye-piece 4.

Fig. 2lB. — Mucor corymbifer. After rupture of the wall of the
sporangium. (After Lichtheim).

Zeiss E, eye -piece 5.

136 CLASSIFICATION OF THE MICRO-ORGANISMS.

into the stalk ; spores colourless, very small, longish,
3 n long, 2 fjb broad.

These two forms were obtained from ordinary white
bread kept at the body temperature. M. corymbifer
was also found by Hiickel in a plug in the auditory
meatus in man. — When the spores are injected into the
blood stream in rabbits, both forms cause the death of
these animals after 48 — 72 hours, the incubation period
lasting 24 hours. On post-mortem examination fungus
mycelium is found chiefly in the kidneys, then in the
mesenteric glands and in Peyer's patches, more especially
in the lower part of the small intestine. The patches
show marked swelling and ulceration. — Injections into
the peritoneal cavity also give rise to the same symptoms.
Dogs are entirely immune, while aspergillus spores pro-
duce disease, though only when present in large numbers.
It is also noteworthy that of the mucor forms only those
can exert a pathogenic action which grow well at the
body temperature. On the other hand it is evident that
this is not the only or a sufficient condition for the
malignant action of mould spores on warm-blooded
animals, for M. stolonifer also flourishes well at high
temperatures, but the spores of this fungus cultivated at
that temperature cause no effect when injected.

In Aspergillus glaucus, Oidiurn lactis, Mucor mucedo,
and Mucor racemosus, we have four of the most widely
spread mould fungi, with which every one who works
with pure cultivations of fission or mould fungi becomes
unintentionally acquainted. There is only one fungus
which excites even greater interest from this point of
view, because it occurs extremely frequently, and is the
The common most common mould fungus : this is the pencil mould,
Pen^c^um) which belongs to the tuberaceae (order :
Ascomycetes).

The higher form of fructification, a kind of truffle, is only
observed very rarely, and under special conditions of cultiva-
tion. It presents the appearance of a small yellow, sand-like

ERYSIPHE 01DIUM.

137

protuberance, and behaves like a thick- walled sclerotium,
and probably, like the perithecia, owes its origin to a sexual
act. On suitable cultivation an ascus-bearing fungus grows
out of this sclerotium, and the ordinary mycelium and fruc-
tification can again be got from the ascospores thus ob-
tained.

Otherwise it is only the conidia fructification of penicil-
liuni which is observed. The fruit hyphse are segmented
and branched like a tree, and a whorl of upright branches
projects like a pencil from the uppermost cell, each
branch bearing either a chain
of spores or another whorl of
branches, terminating in spore- >
chains. Spores spherical, u
cellular. — PenicilliumglaucwTi,
the most common mould fungus
(fig. 22), gives risetoaflocculent
mould growth, at first white, but
later bluish-green. It grows
on the most various nutritive
substrata ; it occurs everywhere,
and hence its spores very often
gain access to cultivations. It
does not seem to flourish at high
temperatures (38° — 40° C.).
The diameter of the spores is
0-0035 mm. ; that of the hyphse
varies according to the food be-
tween 0'004 and 0*00071 mm.
The very stunted forms are un-
branched, and bear only a single
chain of conidia; when the de-
velopment is most luxuriant
several fruit hyphoe become
united to form a thick stem

. \ Fig. 22. — Pemcillium glaucum.

(coremium), at the upper end m? myceiiai hypha with a fruit
of which they again separate hypha passing upwards,
and form chains of conidia, in the manner described
above.

Penicillium spores may be injected into rabbits and other

138 CLASSIFICATION OF THE MICRO-ORGANISMS.

Development animals in large numbers without causing any bad effects.

by cultivation According to Grawitz, however, malignancy can be produced
of malignant t , , ,. . . . . „ , ? , „ J . «.,-•,»•

properties in ^J gradual acclimatisation ot the mould fungi on nuid alkaline

mould fungi, substrata, and at the temperature of the animal body. This
view rests on an error, for Grawitz evidently worked with a
mixture of spores of Asp. flavescens and penicillium : when he
cultivr.t3d this mixture at a low temperature (15° C.) only the
penicillium, which was quite harmless, grew; when, however, he
employed temperatures of 35° — 37° C., the luxuriantly grow-
ing aspergillus overpowered the penicillium, which grows only
imperfectly at this temperature, and the aspergillus cultiva-
tion, which was quite similar in appearance to the penicillium
cultivation grown in the cold, furnished spores of a malig-
nant nature.

Addendum: Actinomyces, Ray Fungus.

A peculiar parasite, the relationship of which was
till recently quite doubtful, may find a place here
provisionally ; I refer to the so-called ray fungus. The
disease set up by this fungus is most frequently observed
Morphological in the jaws of cattle. It forms there a whitish tumour,
theray ' which springs from the alveoli of the molar teeth, or
from the spongy tissue of the bone, expands the latter,
erodes it, and finally bursts outwards, or in rare cases
inwards. The substance of this new formation, which
is in the main soft and juicy, shows on section a large
number of yellowish, abscess-like foci, from which
peculiar bodies are obtained on scraping, about the size
of a hemp seed, of a sulphur yellow colour, and with a
fatty feel. Similar deposits are found in the pharynx,
in the larynx, in the corresponding lymphatic glands,
&c. On closer examination these yellow bodies are
found to present a coarsely granular, often mulberry-like
appearance, and consist of numerous closely interwoven
threads. On slight pressure the round gland-like
bodies break up into a number of fungus masses ; these
are groups of bifurcated threads, like hyphse, which,
gradually spreading out from the centre, end in club or
flask-like swellings (Bellinger). The threads are usually
straight, more seldom slightly wavy, or even spiral, and
they swell more and more towards the periphery. As

ACTINOMYCBS, RAY FUNGUS.

139

they spread out in all directions from a central point,
the resulting struc-
ture resembles that
of a closely packed
bunch of flowers, or
of a druse of crystals.
Since more atten-
tion has been direct-
ed to this peculiar
fungus it has been
often found, chiefly
in cattle and swine.
In cattle it causes
abscesses in the ex-
ternal soft parts of
the head, in the
tongue, and in the
bones of the jaws.

In swine it has
,

been often found in

the Crypts of the

tonsils, without any
accompanying mor-
bid appearances.
Several cases of
actinomycosis of the
lung, and some of
peritonitis, due to
actinomyces, have
also been observed in
cows and swine. In
some instances in-
deed actinomycotic
diseases have appear-
ed endemically; thus
there was an endemic
in Denmark, which
attacked 30 cattle on

One farm. In this Fig. 24.— Actinomyces druse. Section from

case the only thing

Occurrence of
the ray fungus

g. 23.— Druse of actinomyces (ray fungus) in animals-
with an isolated branched thread passing
upwards. (After Ponfick.)

a tumour X 300.

140 CLASSIFICATION OF THE MICEO-ORGANISMS.

that could be suspected as a common source of the disease
was fodder obtained from a newly tilled field (Bang). —
Duncker has also found bodies in pork similar to the ray
fungus, which however are not, according to Johne,
identical with actinomyces.

Occurrence in Masses of actinomyces have been at times observed n
the crypts of the tonsils in man, but here also without
any morbid symptoms. Also in various affections
accompanied by suppuration, such as abscesses in the
neighbourhood of the jaw, in concretions in the lachrymal
duct, in severe suppurations which present the clinical
picture of a prevertebral phlegmon, or of a peripleuritis
with suppuration and metastasis, or of a chronic pysernia.
Lately also five cases of peritonitis of actinomycotie
origin (per. chronica, parametritis, perityphlitis) have
been described by Zemann. In the latter affections the
usual point of entrance must be the intestine, in the wall
of which fresh nodules and scars can be found, or at times
also the Fallopian tubes and the genital apparatus ; in
the case of actinomycosis localised on the face and
neck, carious teeth, injuries to the jaw, inflammatory
processes in the pharynx and tonsils, &c., predispose to
the affection. In all the above mentioned cases, different
as they were in their clinical picture, the same masses of
actinomyces could always be demonstrated in the pus.

to1 animiision ^at ^ ^ungus *s in reality the exciting agent of the
disease is rendered much more certain by the inoculation
experiments which have been performed with isolated
and carefully purified actinomyces masses. The disease
has in several instances been reproduced in calves, by
introduction of the grains into the subcutaneous tissue,
but feeding the animals with them has had no result.
Dogs appear to be insusceptible to the disease ; rabbits
have recently been successfully inoculated in the peri-
toneal cavity by Israel.

Former cuiti- Repeated attempts have been made to cultivate the
fungus, first by Harz, then by Johne, and then by
Israel on solidified blood serum, which was intentionally
made of soft consistence. The results of these cultiva-
tion experiments agree but little with each other, and

ACTINOMYCES, RAY FUNGUS. Ill

these authors do not appear to have succeeded in
cultivating the fungus on artificial substrata through a
long series of generations. Hence we were up till
recently entirely without any guide as to the place
occupied by the ray fungus in the vegetable kingdom.
Lichtheim observed in his investigations on aspergillus
and mucor that a stunted mycelium, closely resembling
the ray fungus, was at times formed in the animal body ;
and this was the only fact, though in truth a very feeble
one, on which a relation of actinomyces with the mould
fungi was provisionally based.

Lately Bostrom has made a preliminary communica- Bostrom's
tion, from which we seem to be approaching an elucidation °l
of the behaviour of the ray fungus in cultivations, and of
its place in the vegetable world. Bostrom employed for
his cultivation experiments not the refracting, club-like
processes, which cannot be cultivated, but the central
network. The grains were placed in gelatine, which
was poured out on plates ; the slow growth of the mass
in the gelatine was not however awaited, but after a few
days the grains which had remained free from contami-
nation were taken out of the gelatine, crushed between
glass plates, and then employed for stroke inoculations
on ox blood serum and agar. These strokes soon acquire
a finely granular, whitish appearance, having become in
the first two days broader and thicker ; then there- appear
in the centre small yellowish red nodular patches, the
borders of which are occupied by extremely delicate,
branched processes, growing from the line of inoculation
at definite distances. These yellowish red masses become
gradually confluent, and covered with a delicate downy
white layer ; at the periphery similar masses are subse-
quently formed. The cultures require seven to eight
days for this stage. The temperature optimum is
between 33° and 37° C. The gelatine is not liquefied by
the actinomyces. The inoculation of such cultivations
on various animals has been repeatedly carried out with
positive results by Bostrom.

Microscopically the cultivations show in the first two
days threads with true dichotomous branching. At

142 CLASSIFICATION OP THE MICEO- ORGANISMS.

first they are segmented at wide intervals, the segments
afterwards become shorter, and when the yellowish red
masses appear in the cultivations numerous very short
rods and some more coccus-like structures are found
lying free and mostly surrounded by a membrane. In
the deeper layers, and on those places where the nutritive
soil is exhausted, the well known club-shaped swellings
appear in connection with the colonies.

According to these results the actinomj'ces does not
belong to the mould fungi, but to the fission algae,
and must be looked on as a branched species of
cladothrix. The place here assigned to the ray fungus is
therefore a provisional one, and can only be maintained
till the publication of more detailed and confirmatory
communications.

II. THE MYCETOZOA.

The mycetozoa, which are as yet but little known,
include the myxomycetes, or slimy fungi, the acrasia,
and the monadina. It is very difficult to define with
certainty the place of the mycetozoa in the vegetable
kingdom on account of their morphological and biological
peculiarities ; they are classified among the fungi because
they form reproductive organs, which resemble fungus
spores ; on the other hand the division of the monadina,
more especially, is placed by some botanists in the
animal world, usually among the rhizopoda, with which
they show many resemblances.

Morphology The myxomycetes have no mycelium; in the young
men^of the*" s^e ^ey ^orm naked protoplasmic bodies, plasmodia,
myxomycetes. of a slimy consistence and of variable form. At the
period of fructification they become converted into
sporangia, in which spores are developed by the forma-
tion of cells. When germination occurs, movable swarming
bodies are developed from the spores, and by the fusion
of large numbers of these bodies a plasmodium is again
formed. The plasmodia form for the most part brightly
coloured voluminous masses, which develop on putrefying
vegetable substrata, on trunks of trees, &c. ; they often

THE MYCETOZOA.

143

flow upwards to higher levels, and send out and again

withdraw simple or branched processes. Und^r favour-

able conditions, of moisture

groups of sporangia are formed

from the plasmodia with con-

siderable rapidity, presenting

the appearance of large pedun-

culated or sessile bladders, only

a few millimeters in size. The

spores fill the interior of the

ripe sporangium in the form of

a dusty powder ; they are simple

roundish cells, with a coloured

membrane ; when they germi-

. i n i

imte they do not send out a cetes (trichia varia) a not

Fig1. 25. — Spores of a myxomv-
cetes (trichia varia) a not

germinating tube, but the pro- £Xlf Son o"f *&

toplasm passes OUt of the Spore amoeboid swarming body.
, ,, f c (AfterdeBary.)

membrane in the form of

swarming spores, which are round or egg-shaped bodies,
with a swinging cilium at their anterior end ; at this end
of the swarming spore lies a cell nucleus, while the other
part contains one or two vacuoles, which alternately con-
tract and dilate, and contain watery fluid. The swarming
spores sometimes swim freely, rotation round ths axis
and side to side movements being caused by the activity
of the cilium ; at other times they creep like amosbae,
protoplasmic processes being sent out and retracted.
The swarming spores multiply by segmentation ; they
finally unite together in constantly increasing numbers,
and thus form again a plasmodium.

The acrasice differ from the myxornycetes only in that Tho acrasiee.
tli3 swarming spores do not fuse together to form
plasmodia, but become closely aggregated and then each
forms a spore.

Themonadina, or the lower mycetozoa, form swarming The monadina.
spores, amoebae, plasmodia, and spores in the same way
as the higher mycetozoa ; they are distinguished chiefly
by the fact that the result of the differentiation of the
plasma in the sporangia is the production of reproductive
cells in the form of mobile swarming spores or amoebae ;

144 CLASSIFICATION OF THE MICRO-ORGANISMS.

the monadina thus form" so-called zoocysts in contrast to
the sporocysts in which resting spores develop (Zopf).

The more highly organised mycetozoa obtain their
nourishment entirely from dead organic materials,
chiefly vegetable, more rarely animal. A large amount
of moisture is a necessary condition for their develop-
Parasitic ment. — The lower mycetozoa, on the other hand, play an
oa" important part as parasites. They chiefly attack aquatic
plants, alga3, fungi, &c., and in consequence of their
rapid development and the ease with which their germs
can spread the diseases of the algae caused by them have
often an epidemic character. But they seem also to be
able to act as parasites on higher plants as well as in
the animal body. Animals which seek their food in
marsh water and in mud seem to be most readily
affected. In the intestine of man also amoebae have
been found, but their characteristics are not accurately
known. It is therefore very readily conceivable that the
monadina, which it would be very difficult to recognise
in the animal body, may deserve marked attention from
a hygienic standpoint on account of their role as
infective agents.

Forthe present only 2 monadinoe need be specially mentioned.

1. Plasmiodopliora, brassicds. — This organism lives as a
parasite in the roots of cruciferae, especially in certain
varieties of cabbage, and causes marked swelling at the part.
Large cells with amoeboid movements are found in the
markedly enlarged cells of the roots, these ultimately become
motionless and divide into a large number of spores, without
previously forming a special membrane. A ciliated swarming
spore escapes from the spore into the water, and eventually
penetrates through the young epidermis of the root into a-
new host.

2. Haplococcus reticulatus. — This organism has been fre-
quently found by Zopf in the muscles of swine. It forms
zoocysts 16—22 /* in diameter, almost spherical, with smooth
membranes. In these 6 — 15 amoebae arc formed at the period of
ripening, and these pass out of thin and ultimately completely
gelatinous places in the membrane. The spores have the form
of spheres, or tetrahedra, with markedly rounded surfaces and
borders, and a diameter of 25 — 30 /* ; on the surface there are
often band-like elevations. In the contents of the ripe spore
there is a large drop of reserve plasma. The mode of sprout-

THE MYCETOZOA.

145

ing of the spores and the further behaviour of the amoebae
have yet to be ascertained. — Flesh, in which the parasites are
present in large numbers, presents a perfectly healthy
appearance; the muscular fibres seem only pressed together,
or pushed out of their position here and there by the parasitic
deposits. Nor is anything abnormal observed in the living
swine. The distribution of the, fungus, which is probably
taken up with the food, seems to be very wide ; Zopf found
that 25 — 72 per cent, of the swine examined were affected.
For further details as. to mycetozoa see Zopf and de Bary.*

Fig. 26. — Plasmiodophora brassicae. (Af ber Zopf.)
-•1 . X 90. Transverse section throug'h a young root of a cabbage seed-
ling. In the epidermic cells (a) amoeboid or plasmodia-like condition
of the parasite.

B, X 90. Section through the lamina of a cabbage leaf ; cells (a, b)
filled with the spores of the parasite.

C, a spore which is just emitting its swarming spore X 600.

/', swarming spores becoming transformed into amoebae X 600.
E, portion of the root of a young cauliflower which shows swelling?
caused by the parasite. Natural size.

* Zopf, Die Pilzthiere oder Schleimpi/ze, Breslau, 1885. " Ueber

Haplococcus reticulatus," Blolorj. C'entralblatt, 1884, No. 22. " Ueber

Plasmiodophora": Woronin, Pringsheim's Jahrb., xi., p. 548. See also

de Bary, Morph. u. Biologic der Pilze ; Mycetozoen u. Baklerien. -Leipzig

1884.

10

146 CLASSIFICATION OF THE MICRO-OKGANISMS.

III. THE YEAST on BUDDING FUNGI.

A common characteristic of all forms of budding fungi
is that they consist of microscopical cells which multiply
by budding, the cell membrane bulging out like a bladder
at one or both ends of the cell, this projection becoming
filled with a part of the contents of the mother cell,
gradually assuming the same size and form, and
finally becoming separated from the mother cell by
a transverse division at the point of attachment of
the bud.

Toruiagrowth A similar yeast-like mode of growth is seen in a
fum??uld number of fungi which under other conditions assume
quite different developmental forms. This is the case
in Exoascus taphrina, where as a rule asci, arranged side
by side in a palisade-like manner, are formed from a
thread-like mycelium ; the ascospores expelled when
ripe germinate in water or in nutritive solutions, and
grow by typical and often repeated budding. This is
also the case with Mucor racemosus when it is culti-
vated below the surface of saccharine fluids (see p. 133) ;
also with Exobasidium, a family belonging to the hymeno-
mycetes, in which the spores developed from basidia
send out yeast-like buds when they germinate. Accord-
ing to Zopf fumago behaves similarly ; and so, according
to de Bary, does Dematium pullulans, which probably
belongs to fumago or pleospora; and this also occurs,
according to Brefeld's most recent investigations, in the
tremellini and ustilagineas (see p. 109).

Budding- fungi This mode of growth by budding is specially developed
proper. jn a cjagg of fungjj which are termed, therefore, budding

or yeast fungi. To this class belong the ordinary yeasts,
the vinegar plant, and the fungus of thrush. It is
probable that they must all be classed among the lower
ascomycetes, and are most nearly allied to the species
exoascus, mentioned above; at least in some typical
yeast fungi a form of fructification has been found in
which spores are formed within the cells corresponding
exactly to the process known in connection with asci.
In the cas3 of other yeast fungi this higher form of

THE YEAST FUNGI. 147

fructification has not yet been observed; nevertheless
the position above indicated may be assigned to the
whole class of the yeast fungi.*

Many of the yeast fungi excite fermentation, and are
able to set up alcoholic fermentation in saccharine
solutions. Nevertheless there are typical budding fungi,
such as the pink torula, &c., which are not able to set
up fermentation ; and on the other hand the yeast-like
developmental forms of mucor, and of other of the above
mentioned higher fungi, have a certain though restricted
power of exciting fermentation.

The peculiar mode of multiplication of the yeast fungi Muitipiica-
goes on to an almost unlimited extent so long as all budding.
the conditions of existence are favourable; the new
formed cells which arise by budding develop fresh
daughter cells which either soon become separated and
continue to grow as independent individuals, or remain
united to the mother cell for a time, and thus give rise
to chains and masses. The cells have a spherical or
oval form, are surrounded by a thin colourless membrane,
and contain a granular protoplasm, in which are vacuoles
filled with cell juice.

By a special mode of cultivation it is possible to By spore for-
obtain multiplication by ascospores in various forms of m
yeast (beer and wine yeast, mycoderma of wine) . If the
yeast is cultivated, after being washed and freed from
adhering wort, on solid moist soil which provides little
nourishment, e.g., on slices of potato or carrot, two or
more round cells appear within the mother cell by free cell
formation just as in spore tubes, these young cells being
surrounded by a thick membrane and becoming free
after some time by solution of the wall of the mother
cell ; in other cases the cell contents contract so as to
form a single spherical body. The spores thus formed
germinate in sugar solution, and develop in the form
of ordinary yeast.

At times a tendency to form mycelial threads is Formation of
observed. If the yeast is cultivated on the surface of

* De Bary 1. c., p. 292. Compare the contrary views of Brefeld in
Botan. Unferstichungen uber Rtfepilze. Leipzig, 188?.

148 CLASSIFICATION OF THE MICRO-ORGANISMS.

solid substances with free entrance of air the yeast-lik
buds lose their distinctness, the strangulations become
less deep, and the whole chain takes on more the form
of an elongated hypha-like cell with thicker and thinner
places. The cellular chain then represents a mycelial
hypha with the apical growth periodically interrupted,
but we never find the formation of a complete mycelium
consisting of true hyphae, or of typical fruit-bearing
hyphae. A marked formation of threads was observed
by Grawitz in the cells of mycoderma vini, and the less
the amount of sugar present in the nutritive fluid the
longer were the threads that were formed ; but constric-
tion of the apex or a subsequent segmentation were
never noticed,

Pasteur's Pasteur and Hansen describe under the name of torula a

group of yeast fungi which do not form ascospores or
mycelial threads even on the most various solid substrata,
but multiply only by budding as in saccharine fluids. They
also occasion very slight or 110 alcoholic fermentation in these
fluids, nor do they lead to the formation of a scum on the
surface. These torulae, of which Hansen describes five
different kinds, are in some places very widely distributed,
and can easily be confused with true yeast, because a mor-
phological distinction between the two budding forms is not
possible. With regard to these torulae it is most probable
that they are only development stages of other fungi.

It has not as yet been possible to distinguish in a
satisfactory manner between the different kinds of yeast
fungi by morphological and biological character "»,
because there was no method of cultivation by which we
could isolate them, and thus obtain with certainty a
pure cultivation of the individual forms. It is only
lately that such a separation and classification has been
attempted by Hansen and other investigators, but up to
the present these attempts Lave not been sufficiently
satisfactory to be of use for a handbook. Of the species
formerly distinguished from one another, the following
may be mentioned here : —

The most im- Sciccharomyces cerevisia (Cryptococcus cer.), the
yeast of beer or brandy. Cells spherical or oval, 8—9

THE YEAST FUNGI,

X49

/A* iii length, single or with hranches composed of
short chains. Three or four spores in the mother cell,
1— 5 /Lt in diameter. Employed in the brewing of beer ;
in the low fermentation which goes on slowly between
4° and 10° C., the yeast is deposited at the bottom of
the vessel (unter-hefe) , and the cells are for the most
part single, or united in small numbers. In the high
fermentation, which takes place between 14° and 18° C.,
the stream of carbonic acid carries up the yeast to the

Fig. 27. -Saccharoinyces cere visile

(yeast).

A, slightly enlarged.

H, low yeast highly magnified.

C, upper yeast highly magnified.

Fig. 28. — Spore formation in
saccharomyces cerevisiffi.

(After Rees.)

a, b, cells with several vacuoles.
c, cell with uniform granular

contents.
(I, four plasma portions.

e, young spores arising from

these.

f, the same with double con-

tours.
<7, free spores after solution of

the membrane.
A, commencing sprouting of the

spores.

surface of the fluid, and this upper yeast (dber-hefe)
contains branched bands composed of several buds. — The
upper yeast is employed in baking to raise the dough ;
it further serves for the formation of the compressed
yeast. — On plates of nutrient gelatine the colonies form
after two days small white points, so long as they are
beneath the surface ; as soon as they reach the surface
they form somewhat more extensive white drops, or dry
masses. Under a low power the colonies appear
yellowish-grey in colour, and with a rough contour, like

* The mark M, which is much used in the following pages, signifies
a micromillimeter=0'001 of a millimeter.

150 CLASSIFICATION OF THE MICRO-ORGANISMS.

mulberries or bramble berries ; here and there we see
irregular processes which look like fine knotted strings.
Under a somewhat higher power it is evident that these
colonies are composed of a number of individual cells.
In test tube cultivations they grow similarly and more
luxuriantly on the surface than in the substance of the
jelly, and send out relatively thick processes.

Sacch. cllipsoideus, wine yeast. Cells elliptical, as a
rule 6 ft in length, single or in short-branched chains ;
usually 2 to 4 spores in a mother cell, 3 to 3 J ^ in
diameter. — This is the chief fungus of spontaneous
fermentations, especially of the fermentation of wine
juice, hence it is present everywhere. — Sacch. conglom-
eratus. Cells round, bound together to form balls. It
occurs on decomposing grapes, and at the commence-
ment of the vinous fermentation. — S. exiguus. Cells
conical or circular, 5 //, long, up to 2' 5 p thick* It
appears in beer yeast during the after fermentation.—
S. pastorianus. Cells oval or club-shaped. The
colonies consist of primary club-shaped joints 18 to 22 ju,
in length, which form secondary lateral roundish or
oval daughter cells 5 to 6 p in length. It forms 2 to
4 spores. It occurs in the after fermentation of wine
and cider, and in the fermentation of beer. — S. apicu-
latus. Cells citron-shaped, with short points at each
end, 6 to 8 p in length, 2 to 3 p in breadth; its buds
are only at the pointed ends. Seldom united in
colonies. Spores unknown. Occurs along with other
forms of yeast in various spontaneous fermentations.
— S. sphcericus. The basal cells of the colony are
oblong or cylindrical, 10 to 15 //, in length, 5 ^ in
breadth ; the other cells are spherical, 5 to 6 fj, in
diameter, united in branched families. Spores un-
known.

Sacch. mycoderma (Mycoderma cerevisiae et vim,
Kahmpilz). Cells oval, elliptical, or cylindrical, 6 to
7 p long, 2 to 3 IJL thick ; form chains with numerous
branches. The spore-forming cells may be as long as
20 p ; 1 — 4 spores in every mother cell. Forms a scum
on fermenting fluids, and grows on the surface without

THE YEAST FUNGI. • 151

exciting fermentation ; it is found especially on wine,
then on beer, juice of fruits, sauerkraut, &c.

Formerly it was supposed that this organism caused acetic
fermentation in fermented fluids ; but according to Nageli
the relation of the fungus to acetic fermentation is not a
causal one. It is found especially on the surface of markedly
acid fluids, e.g., wine poor in alcohol ; in that case it occasions
no formation of acetic acid, the latter is due rather to
specific fission fungi, which, however, cannot vegetate in
markedly acid fluids. This fungus acts in the first place like
a covering of mould, it leads to the combustion of the acid,
and diminution of the amount of acid in the fluid. Thus it
prepares the soilfor the reception and multiplication of the
fission fungus which produces acetic acid; the occurrence
of this scum is therefore a necessary preparation for the
acetic fermentation. Nageli distinguishes the following
scums on fermented fluids : 1. Acetic mother (Essigmutter),
a very thick, tough, glue-like scum, with a smooth surface ;
oxidises the alcohol to acetic acid, consists of bacteria=
Mycoderma aceti. 2. Acetic skin (Essigliautclieri), thin,
slimy, smooth, or finely wrinkled, oxidises the alcohol to
acetic acid, consists of bacteria=Mycoderma cerevisiae. 3.
Mesentcric skin (KaJimliaut, Gekrosehaut) , comparatively Composition
strong and firm, folded like the mesentery, consists of yeast
fungi (Saccharomyces mesentericus), which destroy the fruit
acids. At a later period the acetic fungus (bacterium)
appears in the material, and oxidises the alcohol to acetic
acid = Mycoderma vini. 4. Smooth skin (Falsclie Kahmhaut,
Glatthaut), comparatively strong, but without folds, of a
loosely granular composition, consists of yeast fungi, does
not destroy the fruit acids to any marked extent, and does
not permit the acetic fungus to settle in the fluid. 5. Acetic
ether skin (Essiyatlierlidutclieri), thin, not folded. Composed
of yeast fungi (Saccharomyces sphaericus) and of bacteria
(acetic fungus), the combined action of which converts a part
of the sugar into acetic ether. — The acetic mother and acetic
skin are formed on alcoholic fluids, which contain few fruit
acids, but on the other hand may contain a good deal of acetic
acid; for example, on beer, on vinegar, to which wine or
beer is added, seldom on slightly acid wine. The other
skins, on the other hand, appear constantly on fluids which
contain a certain quantity of fruit acids, the mesenteric
skin on fermented wine juice and other fruit juices, the
smooth skin at times on similar fluids which are altered by
the addition of sugar and other materials. — More recent
investigations by Hansen 011 the membranes occurring on

152 CLASSIFICATION OF THE MICKO-ORGANISMS.

beer have given the following results : if the surface is grey
and dull, Sacch. mycoderma is exclusively or chiefly present,
and numerous air bubbles appear between the groups of cells ;
if the surface is glistening and slimy, the membrane consists
of microbacteria, and the fluid is then muddy and discoloured.
Under a membrane consisting exclusively of Mycoderma
aceti, Mycoderma Pasteurianum (see description of both
among the bacteria), or Sacch. mycoderma, the fluid is always
clear and unaltered in colour. A temperature between 30°
and 34° C, is particularly favourable for Myc. aceti and
Pasteurianum. Sacch. mycoderma grows best at 15° C., at
higher temperatures it is difficult for it to hold its own against
the bacteria; above 26° C. this becomes practically im-
possible.

If this fungus is compelled to vegetate beneath the
surface of fluids, a small quantity of alcohol is formed,
but the fungus soon dies.

In watery, acid fluids, poor in sugar, the cells often
form long tubes, which then send out further buds,
become transversely divided, and finally break up into
single cells. The latter again bud in a similar manner
The fungus of (Cienkowsky). — This structure is most pronounced in
the case of Sacccharomyces albicans, the fungus of
thrush (formerly described as Oidium albicans). Accord-
ing to Rees and Grawitz this fungus resembles very
closely the S. mycoderma, if, indeed, it is not identical
with it, Cells partly spherical, partly oval or cylin-
drical, 3*5 — 5 //. in thickness ; the cylindrical cells are
10 — 20 times as long as thick. The budding colonies
consist for the most part of rows of cylindrical cells,
from the ends of which rows of oval or spherical cells
sprout out ; spores single, formed in roundish cells.
Occurs as thrush on the mucous membrane of the
mouth, especially in suckling children, and forms
greyish-white patches which contain also epithelium,
schizomycetes, yeast cells, and mycelia of different
mould fungi. The thrush fungus is easily cultivated on
solid or in fluid nutritive substrata, which contain,
besides sugar, tartrate of ammonia and inorganic salts ;
according to the amount of sugar present, the cells
either sprout out to form long threads, or, in strong
saccharine solutions, 4 — 8 daughter cells project from

THE YEAST FUNGI. 153

one mother cell in various directions, these daughter

Fig. 29.— The thrush fungus, Saccharomyces mycoderma.
(After Grawitz.)

A, sprouting spores highly magnified.

B, branched mycelium with a few .lateral buds, cultivated in dilute

nutrient solutions.
<\ at a the yeast stage, at b the mycelium stage of the thrush fungus.

cells being for the most
part round and arranged
in roll-like rows. — The
fungus is able to set up a
very mild alcoholic fer-
mentation. Spore forma-
tion has not as yet been
observed.

As the result of more re-
cent investigations, Plaut
does not regard S. myco-
derma and the thrush fun-
gus as identical ; the first sets up only minimal fermentation

©

o

Fig. 30.— Pure cultivation of the
thrush fungus on a nutrient soil
containing sugar. (After Plaut) .

154 CLASSIFICATION OF THE MICRO-ORGANISMS.

with simultaneous death of the cells ; further, it readily
forms spores, its cells approach more and more the form
of spindles or ellipses, and are not ahle to cause thrush
when inoculated on fowls. The thrush fungus, on the
other hand, sets up marked fermentation with simul-
taneous luxuriant vegetation, forms no spore^, the cells
are more spherical, and it causes distinct thrush when
pure cultivations are inoculated on the crop of fowls.
The experiments on animals require to he extended and
completed, in them more especially lies the decision of
the question of identity.
Rose-coloured Pigment-producing yeasts are also known :

Saccharomyccs glutinis (Cryptococcus gl.) Cells
spherical, oval or short cylinders, 5 — 11 /A long, 4 /A
broad, isolated or united in pairs. Cell mernhrane and
contents colourless in the fresh state, when dried and
again moistened they show a faintly reddish nucleus
in the centre. Spore formation unknown. — Forms rose-
coloured slimy coatings on slices of potato, nutrient jelly,
&c. In the latter, when inoculated by pushing a needle
into the substance of the gelatine (puncture cultivation) ,
the growth beneath the surface has the appearance of
white threads shooting out on all sides ; marked growth
and the production of colouring matter only take place
on the surface. The colouring matter is not altered by
acids and alkalies. The pink torula is apparently very
widely distributed ; in our neighbourhood one or more
colonies appear on every jelly plate exposed to the air
for a short time. According to Hansen there are three
different varieties of pink torula, of which one forms
ascospores, while a second gives rise to germinating
tubes of peculiar form when the nutriment is insuffi-
cient.

A brownish-black yeast is also at times present in
water and air; a more detailed description cannot as
yet be given.

THE FISSION FUNGI. 155

IV. THE FISSION FUNGI, SCHIZOMYCETES.

Under the fission fungi or bacteria* is included a
large group of minute, unicellular, spherical, or thread-
like organisms, which multiply by fission. As they are
ordinarily devoid of chlorophyll, they are, like the fungi,
compelled to lead a parasitic or saprophytic existence.
Multiplication and assimilation of nutriment usually
occur with such energy that intense alteration and
destruction of the nutritive substratum is the result of
their development ; they are often able to increase this
decomposition still more by setting up fermentation,
and in the cases where they lead a parasitic existence
they are wont to bring disease and death to their host.

1. General Morphological Characters.

The fission fungi exhibit great varieties in external General
form. Some grow as spheres or oval cells ; this form o
growth is termed micrococcus ; if the spheres form

Fig. 3lA. — Various vegetative forms X 700.

a, micrococcus, isolated. b, in the act of subdivision (diplococcus.)
c, streptococcus, torula. d, zooglaea.

chaplet-like chains the organism is termed streptococcus
or torula; if arranged in irregular masses it is dis-

* De Bary prefers the term Bacteria because some varieties contain
chlorophyll, and are thus not true " fungi." The term " Bacterium"
was formerly employed for a division of the fission fungi; as, however,
this division can no longer be maintained, there is no objection to
de Bary's suggestion. Other names for this class are: Microbes,
Champignons, Torulacees, Bacteries (Pasteur); Mikrozymas(Bechamp) ;
Spalthefe (Niigeli) ; Mikrosporinen, and Monadinen (Klebs) ; Cocco-
bacteria — with the subdivisions Mikro- Meso- Meg-acoccus, Mikro-
Meso- Mega-bacteria — Gliacoccus, Petalococcus, &c. (Billroth).

156 CLASSIFICATION OF THE MICRO-ORGANISMS.

Various

vegetative
forms.

Spores.

tinguished from the former as staphylococcus. Other
fission fungi grow in the form of rods, the longitudinal
diameter being markedly greater than the transverse;
for this form the term bacillus is employed. (Formerly
a distinction was made between the shorter rods,
bacterium, and the longer rods, bacillus, in which the
one diameter is more than two or three times greater

t f*

Involution
forms.

r-o ,

:,*

Fig. 3lB.— Various vegetative forms X 700.

«, bacilli ; b, clostridium ; c, threads, pseudo-threads ; d, apparent
branching ; e, vibrio ; f, spirillum ; g, spirochaete ; h, spores.

than the other.) Bacilli which are swollen in the middle
or spindle-shaped have the special name clostridiiuu.
Where the bacilli are much elongated we have true
threads, or where several bacilli are arranged in a longi-
tudinal direction so-called pseudo-threads ; this thread
form is sometimes termed leptothrix. The threads and
pseudo-threads never show true branches like the hyphae
of the mould fungi ; at the most pseudo-branches are
formed by the peculiar apposition of several threads
(fig. 31, I). In many forms the bacilli or threads are
regularly wavy or corkscrew in form, and these represent
the vegetative form termed spirillum or spirocli&te. If
the turns of the corkscrew are not markedly developed,
and if the spirilla appear more elongated, the organism is
termed vibrio. Loops of threads, the ends of which are
wound around each other like a plait of hair, are
termed spirulina.

Another form which the fission fungi not uncommonly
assume is that of spores. These are spherical or oval
cells which serve only for the diffusion and the main-
tenance of the species, and always sprout and form again
organisms similar to the mother forms from which they
arose.

Further, the fission fungi when grown in exhausted
soil and under various other conditions present all sorts

GENERAL MORPHOLOGICAL CHARACTERS. 157

of aberrant forms which are due to their involution and
decay; flask-like swellings may be associated with
stunted, shrunken, and broken up forms.

It is a characteristic of many
fission fungi that they only occur
under one form of growth, e.g., only
in the form of micrococci. Other
varieties of fission fungi present
various forms of growth through Fis- 32.— Involution

... i • T -I i • forms.

which each individual passes in a
definite order during its development; thus many bacilli
grow to threads ; in the threads spores are formed, and
from the spores bacilli are again developed. The bacillar
thread and spore forms belong therefore to the cycle of
development of this bacterium.

Besides the general characters of the vegetative forms
which have been described, some slighter morphological
differences characteristic of the one or other species
can be made out in spite of the small dimensions of the
fission fungi. Either it is the size of the individuals Morphological

,.,.,.. ,, . , differences in

which is ol importance, the one form growing only as the same
very large cocci (megacoccus) , which have a diameter f03|mtatlve

Fig. 33A.— Morphologically Fig. 33s.— Morphologically

different cocci X 700. different bacilli X 700.

of 1J to 2 ft or more ; other kinds forming very small
micrococci 0*1 to 0*2 //. in diameter, &c. Still more Morpholog-i-
manifold and typical differences are found among the specie"
bacilli; those of one species may be lank and thin,
those of another short and thick ; the one very large,
the other extremely fine and delicate ; or the one may
have the ends rounded off or almost pointed, while the
other are sharply truncated or even somewhat concave.

Individual differences in form may also occur in one Individual
and the same species of bacterium. In this respect the tia^ame^
age of the individual is of the greatest influence ; young 8Pecies-
bacilli appear shorter than older forms ; cocci just
formed by fission are often smaller tb^n those which

158 CLASSIFICATION OF THE MICEO-OBGANISMS.

are about to undergo fission. The nutriment has also a
certain influence ; according to the medium in which
the species in question is cultivated, and according to
the more or less favourable state of all the conditions of
life, slight differences in size and thickness appear, and
fully developed or stunted individuals are formed. As

a I c d e f g

Fig. 34. — Individual morphological differences dependent on age
and nutriment X 700.

f, cocci. Various conditions of age and nutrition of the same species.

b c, various conditions of age of two species of bacilli.

d e, modifications of one species of bacillus dependent on the nutritive
conditions.

/ ff, modifications of another species of bacillus dependent on the nutri-
tive conditions.

these factors, however, are of relatively slight intensity,
none of them as a rule destroy the peculiar morpho-
logical character of the species ; in spite of the modi-
fications induced by age and food, certain character-
istics, as for example the relations between longitudinal
and transverse diameter, the form of the ends of the rod,
&c., are so completely preserved in the majority of the
individuals that they are thereby sufficiently characterised
morphologically.

structure of All bacteric cells consist of cell membrane and cell
the fission* contents. The latter have the appearance of ordinary
fungi. protoplasm, are as a rule colourless, except income forms

recently discovered by van Tieghem, which contain
chlorophyll, as well as some putrefactive organisms
stained red by the so-called bacterio-purpurin. Small
oil globules are often observed in the cells ; at times also
dark, highly refracting bodies, which consist of sulphur
(beggiatoa and red putrefactive organisms). Some
bacteria assume a blue colour on the addition of iodine,
and thus show the presence of granulose ; this reaction
is especially marked in the stage preceding the forma-
tion of spores. Nuclei are not found. When the cells
degenerate and die a marked turbidity and granular
degeneration of the protoplasm occurs.

The cell membrane, which must be very extensile in

GENERAL MORPHOLOGICAL CHARACTERS. 159

the mobile forms, is in some species impregnated with
colouring matter. On the outside a further gelatinous
sheath may be recognised which is developed to a very
variable degree in different species of bacteria. At
times it is very distinct, especially after the use of
staining materials, and surrounds the individual cells
as a broad zone, the outer contour of which corresponds
to the form of the cell ; at times the existence of the
sheath can only be suspected from the spaces left
between the closely packed cells.

Some vegetative forms and species of bacteria are independent
always at rest ; thus the spherical cells, and all those
species which only occur in the form of micrococci, bacteria,
exhibit only a trembling movement with very slight
alteration of position which may be referred to unavoid-
able agitation and currents ; they are never seen to
travel over considerable distances. Other forms, bacteria,
bacilli, and spirochaete are sometimes at rest, sometimes
in active movement. This movement consists partly in
rotation around their long axis and partly in bending
and stretching; in many cases the action of flagella
seems to be the cause of the commencement and main-
tenance of the movement. These flagella can be demon-
strated with complete certainty in some
spirilla and bacilli ; but even in them
they can only be seen with the best
lenses, and after special treatment
of the preparation (drying and staining

.., , • • i , -ii Fig. 35. -Bacilli and

with gentian violet, or better with con- gpfriiia with flagella.
centrated watery solution of hoBmatoxy-
lin). At times their presence is only betrayed by the
peculiar whirling movement of the fluid surrounding the
ends of the cells. The movement of the swarming bacteria
takes place forwards and backwards in the direction of
the long axis ; at times it is slow, oscillating and roll-
ing, at times active and dcarting, so that the field of the
microscope is traversed in a moment. Various alter-
ations of the external conditions, such as change of
temperature, exclusion of oxygen, &c., cause slowing
and cessation of the movement.

160 CUL8&IFIC1TIOS OF THE MICRO- OK,.

In the quiescent state the fission fun^i either remain
isolated or aro united in threads, or in extensive da:

massive colonies. In the latter cases the daughter cells
which arise l>y fission do not become separated, but remain
united by their gelatinous capsule; ultimately lar^o con-
glomerations of cells are formed which are all ui'.itod by
gelatinous intercellular substance. This form is termed
toogl&a; it is most frequent in the microoocei and
bacteria, but it is also observed in short bacilli and
spirochftte. The external form of the aoogl*ea masses
is >ery various: sometimes they are spherical, some-
times tuberous, sometimes lobate ; at times a Yery
peculiar tree-like branching occurs; in certain cases
thick cartilaginous capsules are formed. As a whole
the loogl&a formation is closely similar to the forma-
tion of gelatinous capsules in some families of alg»
(phycochromacese) .
r The multiplication of the bacteria by fission takes

pl*se us * ruk continuously in the same direction, so
that if the new formed cells remain attached to each
other, a chain (streptococcus) or a thread is formed. It
is only in some mierococci (mikr. tetragonus, sarcina)
that simultaneous or subsequent division in two or three
different directions may be observed, leading to the
formation of flat groups of four or packets of at least eisrht
cells ; the former are designated by Zopf by tl
name merismopedia, the term sarcina being reserved
for the latter. In the spherical bacteria the div
may occur in any diameter, in the rod-shaped ce -
the other hand only in the transverse diameter. K
division Aft cells increase in length ; then as a rule
a distinct constriction appears in the middle, and finally
the two halves separate at this spot. These two inde-
pendent individuals can either undergo further
mentation apart from each other, or they remain r.
by delicate gelatinous material and form chains and
pseudo-threads, the transverse division always occr.
in the same direction ; or lastly, they take p;
formation of loogliea masses, gelatinous material tvini:
produced in considerable quantities ; in the interior of

PROPAGATION BY SPOT 161

this zoogkea mass the division of the individual cells
can continue, leading to a denser accumulation in the
zooglaea. — The fission is as a rule completed very
rapidly ; at 35° C. complete division was observed in the
bacilli at the end of 20 minutes ; external and individual
influences may cause variations as regards the time, but
it is evident that the the fission fungi can multiply to
an enormous extent in one or a few days. If we start
with a single bacterium and assume that each indi-
vidual requires an hour to grow and divide, we find tha
in the course of a day about 16 million organisms
have been formed, while by the end of the following
day the number has reached several billions.

2. Propagation by Spores.

Besides multiplication by fission we find a true fructi-
fication, a spore formation, in many fission fungi under
special circumstances, chiefly, but not exclusively, when
the nutriment is becoming exhausted. Fructification
by endospores and by arthrospores may be observed ; of
these the first is the most important and most definitely
ascertained mode of spore formation. This occurs in
various bacilli, and perhaps in some spirilla, but the
process varies in different species. In many cases the
bacilli grow to ^^

long threads be- ^r ^ \

fore the forma- f * . ft %t &

tionof spores;) J'/Hj /, I JV
under favourable "I I • fl I*

conditions they ywr M —SOOT* <<—n~- s. ,r«4~., t^u ^

J -*• *& * <W*- £?JA/TV I CrKTHBUCm Tm W1QW jEDKMf Off

may attain even wan x 7*t.

in a— 4 hours 20 times the length of the original
bacillus. The threads may be nrach twisted, united in
bundles or interworen to form a thick network, and they
have pale homogeneous contents. After some hours the
segmentation of these pseudo-threads begins and becomes
more distinct; at the same time the contents become
turbid and less in amount, and highly refracting granules
appear in the threads at regular inteirals. Afterabooi

II

162 CLASSIFICATION OF THE MICRO-ORGANISMS.

20 hours highly refracting spores with dark contours,
and for the most part egg-shaped, are formed from these
granules, and the threads present a moniliform appear-
ance ; the latter become gradually dissolved, and the
spores are liberated and sink to the bottom of the fluid.
In another mode of spore formation the bacilli do not
grow out in the form of long pseudo-threads, but become
broader; they thus assume spindle, elliptical, or tadpole
'forms, while at the same time the whole plasma becomes
denser, and the membrane thickened. The contents then
become turbid, and highly refracting largish drops are
differentiated and transformed into the spores (spore
formation in Clostridium butyricum according to Praz-
mowski). In other cases 2, 3, or more small spherical
refracting points, which represent the spores, appear in
the bacillus without the latter having undergone any
marked alteration ; or a spherical or oval spore which
often markedly exceeds in diameter the parent bacillus1
develops at one etid of the rod. If a similar spore
formation occurs at both ends of the bacillus, bodies are
formed of a dumb-bell appearance. At times the spores
bulge out the contour of the bacillus in a remarkable
manner, so that the latter appears as if covered with
small swellings.

The spores formed in this way within the cells appear
when isolated as spherical, generally however longish
egg-shaped cells of 1—2*5 JJL in longitudinal diameter,
and 0*5 — 1 ^ in transverse diameter. Their marked
refracting power is very striking ; it gives the impression
as if their contents consisted of a bright oil globule. At
the same time the refraction is not altered by boiling
with ether, so that the contents cannot be regarded as
fat, but rather as condensed protoplasm. The thickness
Of the wall is well-marked ; at times two layers, an exo-
sporium and an endosporium, can be differentiated, and
there is often a peculiar clear area around it, which is
sometimes regarded as a spherical clear mass in which
the cells are embedded, sometimes however only as an
optical appearance due to the high refracting power of
the spore.

PROPAGATION BY SPORES. 163

The spores can germinate and form bacilli in suitable Germination
nutrient solutions and at a proper temperature ; but this
seldom occurs in the same solution in which the spores
were formed, nor till after a considerable period of rest.
According to Koch, when the process of germination
begins the clear spherical mass in which the spores
are embedded becomes egg-shaped, and then elongated,
while the spore becomes pale and finally disappears.
According to Prazmowski and Brefeld the spores swell
in the first place, become pale and lose their dark
contour and the clear area around; then half-moon
shaped dark shadows either appear at each end, and the
spore, which is in a state of trembling, dancing move-
ment, sends out a projection on one side like a papilla
which subsequently grows out to form a rod ; or in other
cases the germinating tube .so\ ^

passes out in the direction of ~ c c? &$ ° ° °

the long axis of the Spore, Fig 37.- Germination of spores

the spore membrane having x 80°-

become uniformly thickened in its whole circumference.

The endosporium then becomes the cell wall of the

young shoot, while the discarded exosporium usually

remains for a considerable time near the newly formed'

rod.

In the case of the bacteria which form arthrospores so-called
the fructification simply occurs by individual members arthrospores.
of a chain or of a mass of bacteric cells showing greater
vitality than the rest ; there is often no morphological
difference to be noted between them and the other
-bacteria in the same chain, while at other times the .cells
destined for the maintenance of the species appear to*
become somewhat larger, thicker walled, and filled with
denser and more highly refracting protoplasm. While
the remaining cells of the group die, these segments
form the commencement of new groups (de Bary).

Most spores, especially those formed endogenously, Besisting-
have the character of resting cells, which are more re- power of tllc'

true spore.

sistant than the vegetative cells of the same species.
Some are extraordinarily resistant, can even withstand
boiling in fluids for several minutes, and are only slowly

164 CLASSIFICATION OF THE MICRO-ORGANISMS.

and incompletely destroyed by the most various chemical
agents. It is clear that on account of these properties
the spores possess a special hygienic interest; for
example, the possibility of exterminating a pathogenic
fungus from the surroundings of man by disinfecting
means depends chiefly on whether or not the fungus
in question forms resistant resting spores. — All resting
spores do not show the same high degree of resisting
power; different spores have apparently very different
powers of resistance, but a certain increased power of
resistance, notably the capability of retaining their
vitality for a long time in a dry state, must be held to
be a necessary characteristic of spores. Bearing this in
mind, we require better reasons than have as yet been
brought forward for assuming the existence of the
so-called arthrospores. — The micrococci and most of
the spirilla are probably characterised by complete
absence of resisting spores ; at any rate if we examine
strongly heated mixtures of bacteria to see what forms
have retained their vitality after exposure to a tempera-
ture of 80°— 100 C., we find only the bacilli which form
resting spores, and none of the other vegetative forms.

3. Characteristics of the Cultivations of the Fission
Fungi.

When in considerable masses, whether these consist
i8ticsCof rthe simply of apposed organisms and swarm formation, or
cultivations of Of zooglaea, the bacteria become visible even to the naked
the fiss-.on ° « .1 ,-, -,i T^V -, -,

fungi. eye. In fluids they cause either diffuse or cloudy mud-

diness, or they cover the surface in the form of thin or
thick scums ; or the zooglaea masses form swimming
flakes; or a powdery deposit of bacteria forms at the
bottom, especially when the nutritive materials in the
fluid are exhausted and are no longer able to supply
food for a further multiplication of the organisms.
Some species of bacteria can also undergo extensive
multiplication in fluids or on solids without anything
becoming noticeable to the naked eye. — The appear-
ance of the colonies of bacteria on solid substrata,

CHARACTERISTICS OF CULTIVATIONS OF FISSION FUNGI. 165

containing much water, is especially characteristic.
Solid substrata have of late been employed by preference Advantages of
for the cultivation of the bacteria, and they are useful chiefly foVthe reeog?
because they permit a completely independent develop-
rnent of each individual bacteric colony, while in fluids
the individual species do not grow at a definite spot, but
become mixed with any other species which may happen
to be present. It is therefore only on solid substrata
that the characteristic appearances of the colonies formed
by any given species of bacteria can be observed, while
it is just the external appearances of the isolated pure
colonies which are of the greatest importance, because
they differ in almost every species of bacteria, and be-
cause we can thus obtain much more important charac-
ters and better distinctive marks than we get with the
help of the microscopical differences in form. For this
reason the appearance of the isolated colonies is of special
service in the diagnosis of the species of bacteria, a thing
which is otherwise often very difficult.

As suitable solid substrata we employ either potatoes,
bread-paste, &c., on which the bacteric colonies appear,
sometimes as slimy white, yellow, or reddish drops,
sometimes as drier whitish films, sometimes as diffuse,
gelatinous layers of various colours, and sometimes as
delicate, scarcely noticeable skins ; or we use the so-
called nutrient jelly (see culture methods), which is
prepared by adding so much gelatine to a good nutrient
solution, that the mixture forms a transparent mass,
which is solid below 25° C. This nutrient jelly is
employed for plate cultivations, in which a very small
portion of the bacteric mixture to be investigated is
added to a quantity of the nutrient jelly, which is
liquefied by placing it at 30° C. : after the admix-
ture is complete it is then poured out on a horizontal
glass plate, so that the latter is covered by a layer a few
millimetres deep. The jelly solidifies quickly ; each Character of
individual bacterium in the mixture is thus fixed at a
definite spot, and grows there to form a colony. If the plates.
experiment is successful, i.e., if too many bacteria
have not been mixed with the quantity of jelly, and if

166 CLASSIFICATION OF THE MICRO-ORGANISMS.

they are not sown too closely on the plate, each colony
develops apart from the others, and then shows distinctive
characteristics, sometimes so marked that with some
practice the species of bacteria present may be easily
diagnosed in the development cither of small gelatinous

6 O

©

J O o
O

# »•

^ ^ o

O Q

Fig. 38. — Various colonies on a gelatine plate.

coloured drops, white, yellow, rose-coloured, red, or
violet (fig. 38, a) ; or of very small white or yellow
circumscribed, almost point-like heaps; or of flat, mucous
layers peculiarly bulged out at their borders (fig. 38, I,
e) ; or of branching and twisted threads of surprising
fineness, which run out from a centre for a longer or
shorter distance into the jelly (fig. 38, /, y, //). Or the
organisms in the colony in question have the power of
gradually liquefying the gelatine, in which case a ditch-
like depression is slowly formed around the colony, the
periphery of which surrounds the colony in the form of
a ring (fig. 38, d) ; or a funnel is quickly formed which
is filled with fluid, at the bottom of which the original
colony lies, and which often extends rapidly over large
study of the areas of the plate. Thus the contour, colour, size, mode
low poewe^th of liquefaction, &c., furnish special characteristics foi
each bacteric colony ; and the sum of these distinguish-

Fig. 39. — Youngest colonies of bacteria in gelatine X 80.

ing features increases very considerably when the colonies
are examined with a low power (x 80). It can then

CHARACTERISTICS OF CULTIVATIONS OF FISSION FUNGI. 167

be seen that one colony presents a completely smooth,
sharp outline, another is bulged out or dentate at its
margin, or is provided with small outgrowths, or shows
wavy threads, which run out from the colony and back
to it again. The surface of the former colonies appears
smooth, that of the latter granular ; one is dark, almost
black, another brown, a third light yellow ; some can
scarcely be distinguished from the surrounding jelly by
their colour.

If by this means of distinguishing and recognising
the species of bacteria it nevertheless turns out that
certain species do not differ in their growth on plates,
the growth along strokes, or along a puncture, may
show something characteristic. This is ascertained by Char .icteric-
pouring the nutrient jelly into test tubes, and allowing puncture
it to solidify in some of the tubes in an upright position,
and in others in an oblique or almost horizontal layer.
Then a small quantity of the colony which has grown
on the plate is picked up on the point of a pieco

Fig. 40. — Puncture cultivations in gelatine.

of platinum wire, and long scratches are made on the
surface of the oblique gelatine, while in the other tubes
punctures are made with the wire to the depth of about
4 cm. Along the punctures we either find only small

168

CLASSIFICATION OF THE MICRO-ORGANISMS.

isolated punctiform colonies (provided that the quantity
inoculated was minimal) ; or a thin confluent layer
is formed along the course of the puncture, so that
the line of puncture appears as a thread, while a
delicate layer spreads out at its upper end towards
the periphery of the jelly (fig 41, b) ; or a thick opaque
mass is formed,, filling the channel completely and

Fig. 41. — Puncture cultivations in gelatine.

forming a markedly prominent kiioh at the orifice
of the puncture (figs. 40, a, and 41, a) ; or liquefaction
occurs, beginning slowly at the top and confined to
the vicinity of the puncture, or energetically and
from the first occupying the whole area of the tube
(fig. 41, c). At times a turbidity spreads through
the gelatine, starting from the line of puncture, which
however is not very distinct ; in some cases the jelly
appears smoky, or cloudy, in others the growth is
more in the form of rays, or of a network of threads
Charactcris- (fig. 40, I, c). Where the stroke method is employed
stroke culti- we see whether separate little drops form, whether
rations on these are glassy and transparent, or white and opaque ;
further, whether the growth remains limited to the

gelatine.

DISTINCTIVE CHARACTERS OF THE BACTERIA. 109

line, or whether it spreads more or less rapidly from
it towards the periphery ; whether the spreading margin
is straight or irregular, sinuous or jagged, &c.

In the case of many organisms which liquefy gela-
tine energetically, we may now and then employ with
advantage a mixture of the nutritive solution with agar-
agar, which remains solid at 37° C. ; nevertheless this
cultivating medium does not on the whole show such
characteristic differences in growth. Some bacteria

Fig. 42. — Stroke cultivations on gelatine.

grow only on solidified blood serum at the body tempera-
ture, and may form very characteristic colonies ; finally,
some only grow to visible colonies when free oxygen
is excluded, and can therefore only be cultivated with
special precautions, to be afterwards described.

4. Classification and Distinctive Characters of the
Bacteria.

A systematic classification of the bacteria is a matter
of very great difficulty, because they are so minute
that even by the use of the highest powers of the
microscope only the external form, and not the differ-

170 CLASSIFICATION OF THE MICRO-ORGANISMS.

ences in the structure of the individual cells, can be
recognised ; nor can any marked differences be made out
in the process of fructification, and yet it is that process
which furnishes the most important principle of classifi-
cation in other plants and in the higher fungi. In view
of the extremely numerous species of bacteria which are
already known, and the number of which is rapidly
increasing, an enumeration and classification of these
organisms appears to be indispensable, in order that we
may at least be able to obtain a general view of the
known species, to settle the identity of any species
which may in future come under observation, and to
include new species in the system of classification. This
Necessity for necessity for a definite classification, and for a key for
claSoSa tne diagnosis of the bacteria, is so great, that in view of
of bacteria, the impossibility of forming a classification on the
ordinary scientific principles, we must for the present
put up with some kind of systematic division, although
the principle of the classification may not be founded on
the developmental history, nor have analogies in the
other departments of botany. Just as in the first begin-
nings of a botanical classification any striking external
characters which were of use for diagnosis were employed
as aids for the distinction and classification of the plants,
so we must in the present state of our knowledge with
regard to bacteria employ as means of distinction any
properties of the bacteria, their morphological and
biological characters, their external form, their mode of
growth on certain nutrient substrata, their relation
to oxygen, their behaviour with regard to stains, &c.,
provided that these properties are constant and cha-
racteristic for the individual species, and enable us to
distinguish them readily. We may hope that with the
advances in our optical means, and with the further know-
ledge of the processes of fructification, we may gra-
dually obtain for the bacteria a groundwork on which a
true classification can be built, and we must therefore
thoroughly realise the provisional character of our
present attempts at classification. But to abstain
entirely from these attempts would be in the highest

DISTINCTIVE CHARACTERS OF THE BACTERIA. 171

degree unpractical, and would retard for a long time,
and practically prevent, the further progress of our
knowledge with regard to the bacteria.

In the present state of our knowledge it is best to em- Morphological

, , -, . T . -i i characters of

ploy both the morphological and the biological characters the four chief

of the bacteria for their classification and distinction. -roni)S-

Four great divisions are in the first place made by

selecting a single vegetative form or a definite and

limited cycle of vegetative forms which are common

to a large number of species of bacteria. To the first

belong all those bacteria which only occur in the

vegetative form, micrococcus. In the second we include

the bacilli which occur in the form of rods, at times

fclso in that of threads or spores. The third division -

is composed of the spirilla, which are only met with

in the form of spirals, or of fragments of spirals.

The fourth includes those bacteria in whose cycle

of development a variety of vegetative forms occur.

The chief characteristics of these four divisions are the

following : —

DIVISION I. — MICROCOCCI.

Spherical or egg-shaped cells multiplying by fission, Morphological
and always forming spherical cells ; they do not show the micro-
spontaneous movement. (The micrococci often exhibit, c<
as above mentioned, a trembling molecular movement,
and frequently also an alteration of situation due
to imperceptible currents of fluid. On closer observation
these can, however, be very easily distinguished from
true spontaneous movement.) Further, in the micro-
cocci endogenous spore formation does not occur;
we either observe no spore formation at all (in most
cases), or else so-called arthrospores are present and
are distinguished from the other cells by their size and
refracting character. In some micrococci the cells
are not accurately isodiametric, but the one diameter
exceeds the other to such an extent that an oval or
egg form results. Further, the spherical form is often

172 CLASSIFICATION OF THE MICRO-OfcGANIbAIS.

not distinctly marked when the act of fission has
begun, and while the two cells still adhere to one
another and the constriction is incomplete (diplococcus) .
The cells which are undergoing division are under
these circumstances elongated with a sharp and more
or less deep constriction in the centre, so that they
resemble a short rod. A comparison with neighbour-
ing individuals not yet undergoing division, or with
those in which the division has proceeded further and
led to distinct formation of two spheres, is as a rule
sufficient in such a case to enable the diagnosis to be
made as against bacilli. After the division is complete,
the micrococci either remain isolated or they assume
short bacill:-. the various arrangements mentioned on page 156,
staphylococcus, streptococcus, merismopedia, sarcina,
zooglsea. If in the zooglaea formation the intercellular
substance is very tough, so that cartilaginous masses are
formed enclosed in the general mass, the group is termed
ascococcus; if the gelatinous masses of such groups
become dissolved in the interior, so that only a thin ex-
ternal layer surrounds a hollow cavity filled with fluid,
the arrangement is termed clathrocystis.

Distinction

DIVISION 2. — BACILLI.
Morphological Rods in which the longitudinal diameter is 2, 3, or

characters of ... f , •, m-i

the bacilli. many times in excess of the transverse. The organ-
isms belonging to the class of the bacilli for the most part
pass through a definite cycle of forms, so that they do
not appear exclusively in the vegetative form, bacillus ;
many can form threads, and in these spores ; in others
there is only well-marked thread formation ; others pro-
duce spores in their middle, at the end, or at several
places, according to the modes described on p. 161 ; most
of them form at times all sorts of involution forms.
We may also meet with these bacteria under many
different forms ; but it is characteristic for all the thread
forms, and round or oval cells, occurring in connection
with the bacilli, that they have been developed from
cells having the vegetative form of bacillus, and that if

DISTINCTIVE CHARACTERS OF THE BACTERIA. 173

they are at all capable of development they again grow

into hacilli under favourable conditions, either directly

or after an intermediate stage. The bacilli occur either

in a quiescent stage, in which case they are often

arranged in threads, heaps or zooglsea, or in a swarm-

ing stage. In many forms, however, the latter stage

has not yet been observed. Now and then a mis-

take may be made between rods and micrococci when

the rods are in an upright position and present their

circular transverse section to the observer's eye ; a

correct conclusion may usually be arrived at by care-

ful examination with repeated alteration of the fine

adjustment of the microscope, and by comparison with

neighbouring individuals. It is at times uncertain Distinction

whether an elongated cell constricted in the middle is mlcTococci

a diplococcus or a rod. The sharp, acute-angled con- bacimortLro

striction which is noticeable after the division of a which arc un-

coccus, and the round form of the two halves, may serve dhXk^ or

as a means of distinction when contrasted with the those which

U»r6 pleLCOCl HL

less acute constriction of the rod, and the fact that the right angles

,.,.,,, • i> . • T-I i to the field of

single individuals are never isodiametric. Even here, vision.
however, it is only after comparison with other reigh-
bouring cells, or after continued observation of the
further development of the individual cell, that an
absolute conclusion can be arrived at. Young br c'lli,
which have just been formed by fission, or by the
sprouting of a spore, often show a very slight excess of
one diameter over the other, and thus approach the
vegetative form, micrococcus, but are easily distin-
guished from it by their further development, and
by the presence at the same time of older forms.
Finally, in the spore form a confusion between bacilli Distinction
and micrococci could also occur, if it were not
that the higher refracting power of the spores, and the
feeble manner in which they take up aniline colouring
matters, formed good points for their recognition ; the
diagnosis is rendered certain by the study of the further
behaviour of the two cells, the sprouting of the one to
form a bacillus, and the multiplication of the other by
division to form fresh spherical colls.

174 -CLASSIFICATION OF THE MICRO-ORGANISMS.

DIVISION 3. — SPIRILLA.

Morphological The typical forms are spirally twisted threads, which
)Ch-ma0f Pr°duce new spirals by fission, and which are for the
most part mobile and often united in swarms. As
to the existence of a cycle of forms in the spirilla
there is very little known, but they seem to have a
special tendency to the formation of involution forms.
In the case of some spirilla it can be distinctly seen
that the spirals are composed of short, curved rods ;
under certain circumstances these rods form the pro-
minent vegetative form, while under other conditions
they become fused together, and spiral threads are
developed. A precise differentiation of these rod-shaped
spiral elements from true bacilli, which often show
a slight curvature in microscopical preparations, i^
frequently very difficult ; and it will probably be im-
possible, as our knowledge increases and transitional
forms are discovered, to uphold the genus spirillum as
an independent division. In the meantime, however, it
appears desirable on practical grounds to group together
m the genus spirillum those curved bacilli in which a
development of spiral threads and a multiplication in that
vegetative form is observed.

DIVISION 4. — FISSION FUNGI WITH VARIABLE VEGETATIVE
FORMS.

Characters of The aquatic fungi studied by Zopf (formerly described
as fission algae) — cladothrix, beggiatoa, crenothrix — can-
not be included in any of the foregoing divisions. In

forms. these fungi, according to Zopf, a manifold cycle of

forms occurs, so that one and the same fungus may
appear in micrococcal, bacillar, and spirillar vegetative
forms. It is possible that in course of time other
bacteria may become known in which an equally exten-
sive series of forms occur. The species which can at the
present time be included with certainty in this group
are comparatively easily recognised and distinguished

DISTINCTIVE CHARACTERS OF THE BACTERIA. 175

by their great tendency to the formation of various
vegetative forms, as well as by a number of other
characteristics.

The external form of a bacteric cell does not of itself afford Necessity for
information as to the species to which the vegetative form a copect con-

j -i-ii • -i • P • ception ana

under observation belongs, but at times admits 01 various designation of

conceptions and interpretations. If, for example, we find a an7 given
spherical cell, it may be a micrococcus, a spore, or an 1%^*
involution product. The cell can only be designated as a
micrococcus when it can be proved that it arose by fission
from a similar spherical 'cell, and that, under suitable circum-
stances, it may again give rise by fission to another spherical
cell. For it is characteristic of the vegetative form, micro-
coccus, that the same spherical vegetative form repeats itself
through a shorter or longer series of cells. If, on the other
hand, the round cell has arisen not by fission but by spore
formation from another bacteric cell, and if it is not capable
of multiplying by direct fission, but must first sprout and
form an individual similar to the mother cell, this spherical
cell must be looked on as a spore. And, finally, if the
spherical form of the cell has arisen from a cell of another
shape only when it began to decay, if this spherical remnant
is no longer able to multiply or propagate itself in any way,
then we have a dead involution structure before us, to which
the term micrococcus cannot be applied.

To take another example: if a twisted or spiral thread
comes under observation, the question arises whether it has
developed by fission from a cell of the same form, and
whether it can again give rise to a cell of a similar shape,
It is not till this is demonstrated that we are justified in say-
ing that we have to do with the vegetative form spirillum
or spirochoete. If this is not the case, it is possible that we
have before us a portion of a thread accidentally twisted, or
some phenomenon of decay which has arisen under abnormal
conditions. It is very important to be clear from the first as
to the meaning and the proper designation of these various
vegetative forms, as otherwise confusion and mistakes
readily occur.

The subdivision of the four chief groups cannot be made Employment
exclusively according to the morphological characters ;

the various species of bacteria which occur in the micro- °f growth for

coccal form more especially show scarcely noticeable distinction" of

ifferences of shape under the highest powers, and even the bactena-

the arrangement of the cocci in chains or masses pre-

176 CLASSIFICATION OF THE MICRO-ORGANISMS.

sents so many transitional appearances that they cannot
be employed as decisive distinctive characters. Here it
is evidently of importance to make use of the manifold
and valuable distinctions described above, those, namely,
which the bacteria show when growing on certain sub-
strata, especially on nutrient jelly. When sub-classes
have been successfully formed by the help of these
differences, the further subdivision of the relatively
small number of bacteria in any small group may be
made by the help of morphological characters, of be-
haviour with staining re-agents, of relation to oxygen, or
of the power of exciting fermentation or disease, and
thus we are ultimately able to recognise a given species by
the study of its various characters as compared with
other species. Of course the species thus formed can-
not in the slightest degree be regarded as natural
species or varieties; they have an entirely provisional
character, and are only meant to serve as a means
of rendering the further recognition of the bacteria
easy, and of paving the way for a natural classification ;
they have only arisen from, and are only suitable for the
Practical practical necessities. Hence the classification given
tiiaSioing the ^ere res^s on that practical method which almost every
bacteria. one now employs who wishes to ascertain what bacteria
are present in any unknown mixture of fungi. The
first step is always an attempt at isolation by means
of gelatine plates ; the colonies which have developed on
the plates can then be easily investigated by making a
.__ microscopical preparation with a small quantity, and ascer-

taining whether the colony consists of micrococci, bacilli,
or spirilla. It is almost always easy to decide this point,
because when we have a large number of similar indivi-
duals all at the same stage of development we have none of
those uncertainties mentioned above which might render
the diagnosis of an individual cell a matter of great diffi-
culty. When the chief division to which the species in
question belongs is thus ascertained, the appearance of
the colonies, both macroscopically and under low powers
of the microscope is investigated^ and then with the help
of a simple table (see p. 178) the relation of the species

DISTINCTIVE CHARACTERS OF THE BACTERIA. 177

to a small group of similar species of bacteria is fixed.
The distinction of these closely similar species is then
easily made by the aid of some very characteristic
reagent, or is a complicated study, and can only be
done by observing the appearance of the growths in
stroke or puncture cultivations, by studying the action
of the cultivation on animals, &c.

Formerly Cohn made the attempt to distinguish a large Cohn's former
number of species of bacteria on the basis of their morpho- c aj| sincatior
logical characters. But exactly similar morphological pecu- schizophytes.
liarities occur in the lower algae ; and it |is essentially only
the absence of chlorophyll which separates the fungi from the
vilgae ; on this point however, as has been said above, no
special weight is now laid. And thus when special attention
is paid to the morphological characters, the resulting classi-
fication of the " schizophytes," must include fission fungi
•and fission alga3. Such a classification is certainly admirably
adapted for placing in correct light certain similarities and
differences between the lower algae and fungi, but it is not
•sufficient for the number of species now discovered, and it no
longer meets practical wants, more especially because a
number of heterogeneous organisms of unequal value from
<i hygienic standpoint are mixed together. In the former
edition of this handbook the author attempted by omitting
the algae to transform Cohn's classification in the following
manner so as to be useful for a circle of readers composed
chiefly of medical men : —

12

178 CLASSIFICATION OP THE MICRO-ORGANISMS.

I Is

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s

o o &

?a la |

'?. ST. 8 «

s c ^

Is 3

o 1>

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S!

<D i^

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s -s

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1 - 1 1 1*1

3 1 -2 *s> §a|

§ § &1 0D "S<£/'&«

f§ (§ ,_; cq cc 02

... Strcptothrix
Cladothrix.
... Myconostoc.

P- : : i i

3 £ :

g S s

ped together to form few loosely united or amorphous families

Threads straight, f Threads short, distinctly segm
Threads
unbranched. j Threads long, r Threads very
1 segments not I
distinct. \ Threads thick

[ Short, stiff
Threads wavy or spiral ;
^ Long, flexile

Threads with false branch formation
i ronndish o-olatinous masse-.-*....

8 ^ Sf

§ I'll

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31

DISTINCTIVE CHARACTERS OF THE BACTERIA. 179

Bearing a doubtful relation to the fission fungi are : Creno-
tlirix, sphserotilus, spiromonas, rabdomoiias ; monas Okenii,
Warmingii, vinosa.

It was frequently stated in the previous edition that this Necessity for
classification is in many points impracticable, that many of the^ormer
the genera cannot be upheld as independent forms, and that classification,
it would have to give place to one more in accordance with
practical requirements. In fact it, has become more and more
evident in the course of the last few years that certain of the
genera up till recently reckoned as independent forms only
represent vegetative and colony forms of various species
belonging to other groups, and that the presence, of gradual
transitional forms greatly increases the difficulty of diag-
nosis. Thus a deposit within a tough gelatinous mass which
was held to justify the classification under ascococcus occurs
more frequently than was formerly supposed, and in bacteria
of different vegetative forms (leuconostoc, clostridium,
polymym, &c.) Again, sarcina cells are spherical micrococci
before the characteristic division into 8 occurs, and often exist
for a very long time as isodiametric cells before the division
into 4 or 8 is apparent ; other micrococci usually occur as
single cells or as diplococci, at times, however, in a meris-
mopedia-like arrangement ; hence this character can be em-
ployed at the most only in a small group of micrococci. As
regards the method of arrangement, clathrocystis closely, re-
sembles the genus ascococcus. Further, a distinction between
bacterium and bacillus is impossible, because there are too
many transition forms which may be placed with as much
right in the one class as in the other. The genera leptothrix
and streptothrix represent a vegetative form which is seen in
many bacilli as an occasional stage of development. Similar
difficulties attend the diagnosis between spirillum and spiro-
chaste as between bacterium and bacillus. Finally, beggiatoa
and cladothrix, on account of their great mutability of form as
discovered by Zopf, must be entirely excluded from a classi-
fication based on the constancy of morphological characters.

Cohn, also, has always regarded his classification as a De Bary's
provisional one, and one only intended as a general guide till c^assification.
a suitable classification is obtained analogous to that of
the higher plants, in which special regard is paid to the
peculiarities of fructification, and to the natural process of
development. Attempts have already been made from the
botanical side to form such a classification. Thus Van Tieghem
and de Bary make 2 great divisions — bacteria which form
endospores, and those which form arthrospores ; but this
division is of little service for practical purposes, because it
is just the mode of spore formation which is most difficult to

180 CLASSIFICATION OF THE MICliO-OEGANISMS.

ascertain in investigating a fungus, while on. the other hand
this subdivision only indicates the first beginnings of a
scientifically correct classification.

Zopf 's classifi- Another classification of the bacteria has been made by
bacteria* ^ Z°Pf> He extended tne doctrine of pleomorphism which he
had observed in the aquatic fungi mentioned above to the
other bacteria, original observations, and some made by other
observers, having demonstrated in several cases a change
of form from cocci into bacilli, threads, and spirilla. Zopf is
of opinion that variability of the vegetative forms occurs in
all bacteria, and that though in the case of many bacteria
the comple'te cycle of forms appertaining to them is not yet
known, we may expect that even in the organisms as yet
known only in a micrococcal form, thread-forming stages,
&c., will yet be discovered.

Zopf divides the bacteria according to these views into
4 groups : —

1. Coccacea?. These are as yet only known in the coccus
form. To these the following genera belong: streptococcus
(cocci arranged in threads like strings of beads) ; merismo-
pedia, tablet cocci (division in two directions, leading to the
formation of tablet -like flat layers of cells) ; sarcina, packet
cocci (division in three directions, leading to the formation of
bale-like colonies) ; micrococcus (division in one direction, the
cocci becoming aggregated together in irregular heaps) ; and
ascococcus (the heaps of cocci accompanied by marked forma-
tion of gelatinous material).

2. Bacteriaceae. These possess chiefly coccus, rod, and
thread forms ; the former may also be absent ; in the latter
there is no contrast between base and apex. Threads straight
or screw-like.

Genera: Bacterium, forms cocci and rods, or only rods
which are arranged in rows to form ordinary threads ; spore
formation absent or unknown. Spirillum, threads screw-like,
formed only of rods, or of rods and cocci ; spore formation
absent or unknown. Vibrio, threads screw-like, spore forma-
tion in the longer or shorter joints. Leuconostoc, forms cocci
and rods, spore formation in cocci. Bacillus, cocci and rods,
or only the latter in the form of simple or twisted threads ;
spore formation present, occurring in rods or in cocci. Glos-
tridium, resembles bacillus, but the spore formation occurs in
peculiar dilated rods.

3. Leptothrix. Coccal, rod, and thread forms ; the latter
show a contrast between base and apex ; threads straight or
screw-like ; spore formation not demonstrated.

Genera : Crenothrix, threads enclosed in a sheath, cells with-
out granules of sulphur; inhabitants of water. Beggiatoa,

DISTINCTIVE CHARACTERS OF THE BACTERIA. 181

threads without a sheath, cells with sulphur granules ; inha-
bitants of water. Phragmidiothrix, threads without sheaths,
successive divisions very extensive ; cells free from sulphur ;
inhabitants of water. Leptothrix, threads with or without
sheaths, divisions not very extensive ; cells devoid of sulphur.

4. Cladothrix. Show coccus, rod, thread, and spirillar
forms. The thread form is provided with pseudo-branches.
Spore formation not demonstrated. Genus : Cladothrix.

A priori the possibility of the mutability of form of the Disadvan-
bacteria asserted by Zopf, and to which expression is given in |" ^e
the foregoing classification, must at any rate be admitted ; adoption of
but before we accept it as a matter of fact, and as so general, §°]^ nyp°-
we must demand complete proof, and we must insist the more
strenuously on a satisfactory proof, as we Avould be deprived,
by the admission of extensive changeability of form, of an
important diagnostic aid which is of great value to us in
medical and hygienic practice. We know now a number
of exciting agents of disease which occur, for example, in the
form of characteristic bacilli ; we are able to make a diagnosis
of tuberculosis by the discovery of the tubercle bacillus, and
of cholera by the demonstration of the cholera bacilli. If the
characteristic bacilli are absent on careful and repeated in-
vestigation, and if we find only bacilli or cocci of other form,
we consider ourselves justified in denying the existence of
tuberculosis or of cholera. Further, we frequently undertake
the investigation of some object, which is suspicious from a
hygienic point of view, for the presence of typhoid bacilli, of
anthrax bacilli, &c., and we can only hope for a result because
we search in all cases for an organism of definite and charac-
teristic form. If, however,' Zopf's view is correct, and if these
bacilli often occur in a coccal form, investigations of this
kind must obviously be without result ; it is impossible to
recognise by the microscope organisms in the coccal form, and
hence any extraneous innocent coccus might lead us to the
diagnosis of tuberculosis or typhoid fever just as well as the
supposed coccal form of these pathogenic bacilli. We should
also meet with great difficulties in isolating organisms by
cultivation if the colonies of, for example, the typhoid bacillus
could occasionally contain only coccus forms. We should
then find it very difficult to decide with regard to a group of
cocci whether they should be included in the genus spirillum,
or beggiatoa, or micrococcus, or bacterium, and also to what
species of these genera they belonged.

Complete proof of the accuracy of Zopf's views has certainly Absence of
not been furnished with regard to the great majority of the univerfa?10
fission fungi. Our most skilled microscopists and bacteriolo- applicability

gists have never as yet been able to demonstrate a trans- ?* ZoPf8-

hypothesis.

182 CLASSIFICATION OF THE MICRO-ORGANISMS.

formation of micrococci into bacilli or vice versa. The positive
observations which furnish support to Zopf's views proceed
almost entirely from investigators who have not had a long
and special instruction and experience in bacteriological re-
search. These, however, are the investigators who are most
liable to fall into errors which lead to a mistaken assumption
of an alteration in form, and which are only avoidable by long
practice and particularly careful observations. In the first
place, it may easily happen that any roundish body which is
like a coccus maybe mistaken for a true coccus. Such a mis-
take is possible, for example, with spores and with involution
forms (see p. 175) ; further, young bacilli just formed by fission
show often only a very slight excess of the long diameter (see
Sources of P- 173) ; bacilli standing upright and seen in transverse
error in the section resemble cocci ; by the use of staining materials — a
proof. method to which we owe the most beautiful facts, but which

in unskilled hands is a dangerous means and often leads to
mistakes — a coccus form may be produced by staining very
old bacilli which no longer take up the colouring matter in
their whole extent, or by heating too strongly, or by employ-
ing differentiating materials for too long a time, so that again
only a partial staining results. In investigating cultivations
also, the possibility of contamination from without is never
absolutely excluded, and abnormal forms must always in the
first place be closely tested on the suspicion that they may be
derived from contamination with other fungi; it is only
when we repeatedly obtain similar results after employing
all precautions for maintaining pure cultivations that we can
conclude that all the forms observed have arisen from one
and the same species.
Eefutation of These numerous sources of error certainly justify us in

some state- exercising a certain reserve with regard to the statements as

ments made . « . «

in support of to an extensive alteration in form of the bacteria. Many of

Zopf's these statements have already been shown to be undoubtedly

hypothesis. erroneous . thus Kurth has, in the case of the bacterium
Zopfii which is according to Zopf a striking example of the
great mutability of form of the fission fungi, seen, according
to his own description, spores, but not cocci, originating from
the bacilli ; for these " cocci " did not multiply by fission, but
grew directly to rods in fresh nutritive solutions, and were less
sensitive to external influences than the rods. In like manner
the bodies which Hauser of late saw arising from bacilli, and
which he erroneously termed cocci, do not produce new cocci
by fission; while the spirulina of the same author represent
simple bending and irregular intertwining of threads such
as occurs in every long flexible thread. To mention another
example, we may refer to dc Bary's bacillus megaterium.

MICEOCOCCI PATHOGENIC IN MAN. 183

which is said to occur in coccus forms; this form was
observed " when the cultivations were rendered impure by the
presence of other small bacteria, the species under discussion
retaining, however, the upper hand; the torula-like chain
form can then by purer cultivation be again transformed
into that of the smooth rods." Undoubtedly such a trans-
formation in very impure cultivations is not free from objec-
tion.— Thus a number of apparent proofs of the mutability of Constancy of
form of the fission fungi have been refuted or recognised as un- !P°e™t ma'^orit
certain, while on the other hand we convince ourselves daily of the
how extraordinarily constant the most various saprophytie bacteria,
and pathogenic species of bacteria are when full attention is
paid to all the sources of error. On the ground of these ex-
tensive and daily observations one may now with justice assert
that variation in form does not occur to any large extent in
the majority of the bacteria; that on the contrary most
bacteria pass through only the limited cycle of forms which
are easily observed and permit a diagnosis of the individual
varieties. Should, however, new and unobjectionable investi-
gations demonstrate an extensive mutability of form in one
or other species, these species must then be classed with the
fungi included in the last division of this provisional classi-
fication ; we would, however, be compelled to regard such a Express
state of matters rather as the exception than the rule, and the^s^ibnit
would not be warranted in deducing a law applicable to all of exception*
other bacteria from such exceptional cases, seeing that mani-
fold investigations have always proved the contrary.

I. MICKOCOCCI.

(For characteristics, see p. 171.)

A. MICEOCOCCI PATHOGENIC IN MAN.

Staphylococcus pyogenes aureus.

First observed by Ogston ; cultivated by Rosenbach,
later by Krause and Passet. Small isodiametric cells
about 0*87 ^ in diameter (Passet). Often grouped as
diplococci, at times in 4's, and also in short chains of 3
or 4 individuals, generally, however, in larger irregular
masses. Ketains the aniline stain after treatment with
Gram's fluid (iodine and iodide of potassium solution
and alcohol). — Grows on gelatine plates,* and forms in

* Where we speak of nutrient jelly in the following pages we always

184 CLASSIFICATION OF THE MICRO-ORGANISMS.

Growth on

gelatine

plates.

In puncture
cultivations.

Growth on

two days at the temperature of the room punctiform
colonies, which under a low power of the microscope
present the appearance of light brown circular balls,
dark in the centre and with smooth borders. On the
second or third day the colonies have generally increased
to such an extent that they reach the surface of the
gelatine ; they then assume a characteristic appearance,,
presenting a yellow colour from this time forward, and
also slowly liquefying the gelatine in their neighbour-
hood. The liquefaction becomes evident by the occur-
rence of a very shallow depression around the colony which
is marked off from the rest of the gelatine by a sharp
border. With suitable illumination a number of abso-
lutely circular depressions, 5 — 10 mm. in diameter, are
seen on such a plate, and in the centre lie the yellow
colonies of at the most 1 mm. in diameter. At a later
period the liquefaction extends further, the individual
liquefying centres coalesce, and the colonies break up
into fragments. — The puncture in nutrient jelly shows at
first a white confluent layer along the track of the
needle; liquefaction quickly occurs, beginning at the
surface, and soon, as a rule, occupying the whole tube
up to the glass ; after a few days the yellow coloration
appears, and increases somewhat in intensity up to the
eighth day. The whole contents of the test-tube ulti-
mately become liquid, and at the bottom lies the golden
yellow mass of the deposited colonies.

If agar-agar is employed as the solidifying material
instead of gelatine, no liquefaction occurs, and the
growth of the colonies on the plates can be watched for
a long time, but the very characteristic appearance due
to the slow liquefaction of the gelatine is absent. In
strokes and punctures the agar cultivations have the
appearance of whitish masses, which after a few days
present at the surface a golden yellow colour. The

refer to the mixture containing 5 — 8 per cent, of gelatine described in
detail in the chapter on the methods ; it is only in such a mixture that
the characters of growth of the various bacteria present the appear-
ances described here. Further, a temperature of 20°— 22° C. is generally
employed for gelatine cultivations.

MICROCOCCI PATHOGENIC IN MAN. 185

staphylococcus grows on potatoes in the form at first of
a bright yellow, and later of a thick soft golden yellow
layer. — When inoculated into milk, coagulation occurs
after one to eight days in consequence of the production
of one or several acids, among which lactic acid has the
preponderance. A peculiar sour smell also becomes
evident after some time in the cultivations on potatoes
or agar.

The yellow colouring matter is only formed where Products of
the colony is in contact with free air ; under a layer of gl
oil the cultivations remain white. It is probable from
the peculiar and energetic action of the fungus on the
living tissue of warm-blooded animals that poisonous
irritating materials are produced, and hence it would be
very desirable to obtain a more accurate knowledge of
the products of their growth. Brieger has recently
(Weitere Untersiichungen uber Ptomaine, p. 73) iso-
lated an organic base from staphylococcus which had
been grown in meat infusion. This base does not appear
to be identical with any of the ptomaines as yet known,
and thus seems to be a specific product of the growth of
the staphylococcus ; it did not however prove to be
poisonous to the animals experimented on.

The staphylococcus is remarkable on account of its
relatively great resisting power to external agents ; the
cultivations in gelatine or agar are active after more
than a year.

The action of the staphylococcus on animals varies Action on
greatly according to the mode of application. Subcu- ai
taneous inoculation is without result in mice, guinea-
pigs, and rabbits ; when inoculated on the cornea of
rabbits a small greyish white infiltration occurs, accom-
panied by inflammation which subsides on the fourth day.
After subcutaneous injection the pyogenic properties of
the fungus become evident. It is only in mice, and after
the injection of relatively large quantities, that death
occurs early ; in guinea-pigs and rabbits, on the other
hand, an abscess forms in the first instance, and this
can either heal and the animal recover, or a general
infection may ultimately occur. Intraperitoneal and

186 CLASSIFICATION OF THE MICRO-ORGANISMS.

Renal
deposits.

No physio-
logical excre-
tion through
the urine.

Occurrence in
man.

intravenous injections usually kill the animals after from
two to nine days. On post-mortem examination the
most characteristic alterations are found in the kidneys,
which present the appearance of a septic embolic
nephritis ; whitish yellow masses from the size of pin
points up to that of peas are present, and at times large
wedges which infiltrate the kidney like pyramids. Many
capillaries are completely blocked with thrombi consist-
ing of cocci, as are also the smaller arteries in the cortex
as well as a few straight tubules. Further, purulent
metastases often occur in joints, in the muscles, and,
where fractures have been recently made, in the medulla
of the injured bones ; frequently, however, the latter
situation escapes, although recent fractures are present.
Small quantities of the fungus are at times without
effect, even when injected into the veins ; nevertheless
in these cases also deposits appear to form in the kidneys,
but remain limited and heal.

The deposits in the kidneys do not arise as the result
of the excretion of the staphylococcus by the kidneys,
nor does the localisation occur here in connection with
any protective excretion; on the contrary, it has been
demonstrated by the experiments of Wysokowitsch*
that not a single coccus appears in the urine during
the first six hours after the injection of large quantities
of staphylococcus, and that when cocci can be cultivated
from the urine deposits are always demonstrable in the
kidneys. The cocci introduced into the blood are
deposited in various organs, especially in the spleen, in
the medulla of bone, &c., and they either soon die or
remain for a long time capable of development.

Staphylococcus occurs very frequently in man ; it is the
most common pyogenic organism. The experiments of
Rosenbach and Passet, repeated recently with great care,
have shown that materials mechanically and chemically
irritating (turpentine and mercury) can only excite sup-
puration in extremely exceptional cases, when micro-
organisms are not present at the same time. In almost
all the cases of suppuration which come under observa-

* Gottinger hygien. Tnstitut.

MICROCOCCI PATHOGENIC IN MAN.

187

Fig. 43. — Pus containing
staphylococcus X 800.

tion in practice bacteria are the causal agents, and some
forms of suppuration are more especially caused by
staphylococcus aureus. This organism causes rapid
suppurative destruction of the
tissue, and it excites suppura-
tive phlegmons which spread
more in the tissue than in the
lymphatic vessels. Hence it
is found more especially in
acute abscesses, in empyema,
and in boils ; further, in acute
osteomyelitis, although the
above mentioned experiments
in animals have not demon-
strated with absolute certainty the causal role of this
fungus in that disease. Lastly, it occurs at times in
some severe diseases, accompanied by metastases, in
pyaBmia, and in ulcerative endocarditis. According to
the point of entrance of the fungus into the body, and
according to the numbers which enter, affections of very
different severity may follow. That in reality the staphy-
lococcus cultivated from pus from osteomyelitis is also
the exciting cause of furuncular inflammation has been
proved recently by an experiment made by Garre on
himself, where a culture of staphylococcus, originating
from the pus from osteomyelitis, was rubbed into the com-
pletely intact skin of the arm, and where the organisms
penetrating through canals of the cutaneous glands,
set up furuncles over a large extent of the surface.

Staphylococcus pyogenes albus.

Found frequently by Rosenbach in pus along with
staphyl. aureus. Corresponds in microscopical appear-
ance, in the characters of its cultivations, and in its
relation to animals, with staphyl. aureus, the only
difference being that its colonies remain white even
after a long time ; in old gelatine cultivations a white
deposit is seen at the bottom of the liquefied mass.
According to Passet, staphyl. albus occurs more fre-

188 CLASSIFICATION OF THE MICRO-ORGANISMS.

quently in man than aureus ; according to Rosenbach, on
the contrary, less frequently, and usually mixed with
aureus. In many animals (rabbits) the staphyl. albus
seems to be decidedly the most frequent.

*

Staphylococcus pyogencs citreus.

Found by Passet in a few cases (in 10 per cent, of the
cases) in the pus of acute abscesses. Differs from the
foregoing only in the bright citron yellow colour of its
cultivations, the difference as contrasted with the dark
yellow orange-coloured pigmentation of staphyl. aureus
being distinctly evident, especially in old cultivations.

Micrococcus of the " Clou de Biskra "

By the term "Clou de Biskra, or Bout on d'Alep/'
is meant an endemic disease occurring in Aleppo, Bagdad,
Biskra, and Tunis, characterised by tubercular swellings
on the face and extremities, which develop in the course of
a year, burst, and finally cicatrise. Duclaux has found
micrococci in the blood of these patients, which were less
than 1 n in diameter, occur in the form of diplococci or
zooglaea (thus belonging to the staphylococci), and can be
cultivated in neutralised veal infusion. Twenty drops of
the cultivation injected subcutaneously into rabbits excite
extensive gangrene, but the animals ultimately recover.
Large doses injected into the blood of rabbits kill them
within 16 hours, and on post-mortem examination peri-
carditis, pleuritis, haemorrhagic infarcts in the lungs, &c., arc
found. After the intravenous injection of small doses, a
chronic disease, which gradually gets well, begins after an in-
cubation period of 10 days ; this disease is characterised by the
occurrence of numerous small ulcerating nodules distributed
over the skin of the whole body, and recalling exactly the
disease in man. A confirmation of this observation by the
investigation of other cases of Clou de Biskra must be
awaited.

Duclaux has made a striking observation with regard to
the cultivations of these micrococci. Old cultivations gra-
dually lose their virulence, so that after standing for two
months the cultivations were inactive, even in large doses.
But if fresh infusion was inoculated from these old inactive
cultivations, the new cultivation was as virulent in the first
few days as the former young cultivations, and according to
the dose employed it set up the whole series of morbid symp-

MICROCOCCI PATHOGENIC IN MAN. 189

toms described above. As, however, the experiments were
made only with fluid media there is no absolute certainty
that in these experiments impurities in the cultivations did
not lead to mistakes.

Micrococcus pyogenes tennis.

Found by Kosenbach in a few instances (in 10 per cent,
of the cases examined) as the only micro-organism pre-
sent in the pus of unopened abscesses. Irregular cocci,
somewhat larger than staphylococci, showing in con-
trast to the latter, but little tendency to the formation
of masses. Two dark poles with clear intermediate
substance are frequently observed in the micrococci ; the
cultivations on agar have the appearance of thin deposits
spreading out from the line of inoculation, almost as
clear as glass ; in puncture cultivations a somewhat
thick and slightly opaque layer is formed. No experi-
ments on animals have as yet been made.

Streptococcus pyogenes.

First recognised by Ogston from its microscopical Pyogenic
appearance ; cultivated from pus by Kosenbach, then by 8
Krause and Passet. — Spherical cocci, about 1 //- in dia-
meter, larger than the staphylococci. Eetain the stain
in Gram's method. What is very characteristic, and the
origin of the name of this species, is the tendency of the
cocci to divide continuously in the same direction and to
form chains of 4, 5, or even 10, or
more cocci; these chains are fre-
quently united in delicate loops to
form larger heaps. Besides the chain
form, the fungus often appears as a
diplococcus. At times one or other
cell in a chain is larger than the rest;
it is not certain whether this indi-
cates the formation of arthrospores. — -p[g. 44.— Pus contain-
The streptococcus grows on gelatine ins streptococcus Growth on

i , . ,-, /. ?i x yo°- gelatine

plates in the form of very small punc- plates.

tiform colonies which spread out on the surface as very

190 CLASSIFICATION OF THE MICRO-ORGANISMS.

In puncture
cultivations.

In stroke
cultivations.

Effect on
animals.

small, slightly prominent transparent drops, about J mm.
in diameter. Even after several days there is no
extension of these colonies and no liquefaction of the
gelatine. Under a low power the youngest colonies
present the appearance of round, seldom oval, yellow
spots, with regular contours and finely granular surface.
Later they become somewhat darker, almost brown,
and the border is here and there interrupted by pro-
jecting chains of cocci, which either terminate in a
free end, or form loops ; the growth is somewhat more
marked on agar plates, the colonies are rather broader
and opaque. — Along the track of the puncture in
gelatine a delicate layer appears, which consists, either
entirely or in part, of isolated colonies ; these are of a
faintly whitish appearance, almost transparent, very small;
only a few attain the size of a pin's head. In stroke culti-
vations the streptococcus seldom forms continuous lines,
it usually occurs in discrete centres ; on agar the growth
is thickest in the middle, and becomes gradually thinner
in a terrace-like form towards the periphery ; at the peri -
phery punctiform masses of the organisms can be seen here
and there. — On solidified blood serum the growth is similar
to that on agar; it does not seem to grow on potatoes.

In mice in the majority of cases (about 80 per cent.)
no effect follows the subcutaneous inoculation of small
quantities ; at times slight suppuration occurs at the
point of inoculation, at times the animals die without
the presence of any marked pathological change or of
micro-organisms in any of the organs. If rabbits arc
inoculated on the ears marked redness and swelling
occurs on the following day, but disappears on the
second or third days ; subcutaneous and even intra-
venous injection of considerable numbers of the strepto-
cocci cause as a rule no apparent effect in healthy rabbits.
It is only when the animals are artificially weakened, as
for example by the injection of toxic substances, that death
occurs from marked growth of the micrococci; the animals
also died after 2 — 5 days from extensive endocarditis, with
numerous deposits of streptococci, if the aortic valves
had been injured before the injection (Wysokowitsch).

MICUOCOCCI PATHOGENIC IN MAN. 191

Streptococcus pyogenes is frequently found in pus Occurrence in
from man (in 40 — (50 per cent, of the kinds of pus m
examined) . It occurs by preference in the inflammations
which have their chief seat in the lymph tracks ; it does
not as a rule cause such rapid suppuration and de-
struction of the tissue as the staphylococcus, but it can
penetrate further into the tissue and infiltrate it before
suppuration and destruction occurs. Also in severe
affections, in spreading gangrene, in several cases of
pyremia, cultivations from the pus have yielded only the
strept. pyogenes (compare the following streptococci).

Streptococcus erysipelatosus.

Proved by Fehleisen by cultivation and re-inoculation streptococcus
on man to be the causal exciting agent of erysipelas ; °
the streptococci had already been demonstrated micro-
scopically by other observers. It can scarcely be dis-
tinguished from the preceding either microscopically (also
by Gram's method) or by its behaviour in cultivations.
It is only in the case of the stroke cultivations that Growth in
a noticeable difference at times occurs in so far that Cl
the colonies have a
somewhat greater ten-
dency to run together,
appear more whitish
And opaque, and show ^ . V

at the periphery nu- -•-••: '•£('' • '

merous out -growths / .. ^''•••f^ijSj^

which consist of pro- : -;:/-:

footing chains, and give ^i-'":^^
to the cultivation the - ^Wj-jp^^ ir

appearance of a fern
leaf. Nevertheless
these characteristics
are not sufficiently Fig 45._Erysipeias cocci x 700.

constant to furnish a Section through a lymphatic vessel of

trustworthy point of

distinction between the two cultivations.

Experiments on animals show a slight difference

192 CLASSIFICATION OF THE MICKO-OKGANISMS.

Action on between the two forms of streptococci. Subcutaneous
inoculations in mice are always without effect, the
wounds almost always healing without suppuration. In
rabbits inoculation on the cornea sets up keratitis, as in
the case of streptococcus pyogenes ; inoculations on the
ear cause in the majority of cases an erysipelas which is
recognised by redness and elevation of temperature of
the ear ; it appears later, and is not accompanied by such
intense redness as is the case with the inflammation due
to the streptococcus pyogenes. A sharply limited red-
ness appears in the neighbourhood of the point of inocu-
lation within 36 to 48 hours ; and this extends in the
direction of the veins as far as the root of the ear. In
sections of the affected ear the lymphatic vessels are
filled with micrococci in numerous places. The animals
recover completely after a few days ; intravenous injec-
tions of large quantities of the organisms are also borne
without bad effect.

Occurrence in "While thus only very slight differences can be made
out between these two streptococci as the result of
cultivations and of experiments on animals, they
apparently differ to a marked degree in their action on
man. Strept. pyogenes is present in about the half of
all kinds of suppuration, while the streptococci of ery-
sipelas only occur in this relatively rare contagious
disease, and are able to set up this disease in healthy

Cultivation of people. They can be best obtained, according to

manC°CC1 fr°m Fehleisen, from erysipelas in man. by excising a small
piece of skin from the sharply defined border of an
erysipelas marginatum (not from the earlier affected parts,
in which, as a rule, no living cocci can be found), and
introducing it into a tube containing nutrient jelly ; the
tube is then kept for two hours at about 40° C., so that
the gelatine becomes liquid, and comes into intimate
contact with the piece of skin ; it is then kept at 20° C.,
or better, the contents of the tube are poured out on a
glass plate in the usual manner. After two or three days,
numerous punctiform colonies can usually be found in
the neighbourhood of the piece of skin.

Fehleisen has inoculated these cultivations on man after

MICROCOCCI PATHOGENIC IN MAN. 193

a number (17 and more) of successive cultivations on new Artificial
nutrient jelly, and in these cases typical erysipelas has 3°thea X
resulted. The experiments were carried out on patients
who were suffering from malignant tumours, which
could not he operated on (lupus, carcinoma, sarcoma),
and this was done hecause former experience has shown
that these tumours often improve in a remarkable
manner, or entirely disappear after recovery from an
accidental attack of erysipelas. Such an "erysipele
salutaire " has several times during the last few years been
induced by inoculation of pure cultivations, and often
with good therapeutical results. The incubation period
in the cases observed by Fehleisen extended from 15 to
61 hours ; the disease always commenced with an initial
rigor, elevation of temperature, and disturbance of the
general health. Individuals who had suffered from an
attack of erysipelas a short time (up to some months)
before the inoculation proved to be immune.

Streptococcus pyogenes malignus.

Cultivated by the author from necrotic masses in a
leucaemic spleen. Not distinguishable microscopically
from the streptococci previously described, the cultiva-
tions are also very similar in appearance; the colonies
on gelatine plates and in puncture cultivations appear
somewhat smaller and grow more slowly, so that they do
not begin to be visible till after about 48 hours. The
stroke cultivations resemble most closely those of
Strept. pyog. — Experiments on animals yield results
which differ in an important manner from those attained
by the other streptococci ; mice inoculated subcu-
taneously with small quantities of the cultivation die
almost without exception after 3 — 5 days; a large
collection of pus is found at the place of inoculation, a
moderate number of diplococci and short chains of cocci
in the blood and especially in the spleen, at times also
deposits of micrococci in the internal organs. The
disease may be transmitted to other mice by small
pieces of the tissue, or by the blood, if not in too small

13

194 CLASSIFICATION OF THE MICRO-ORGANISMS.

quantities. Rabbits, after inoculation on the ear, show
at first almost the same appearances as after inoculation
with Strept. pyog. and with Strept. erysip. ; but after
two or three days a general infection occurs, and death
follows on the fourth day ; the post-mortem appearances
are similar to those found in mice ; some of the joints
are also frequently affected, and filled with pus contain-
ing numerous cocci. It is probable that the Strept.
pyog. described by Krause, and which differed in it&
malignant effects on animals from the coccus isolated
by Rosenbach and Passet, is identical with this organism.

Streptococcus articulorum.

Loeffler has observed chain-forming micrococci on and
in the diseased mucous membrane in various forms of
diphtheria ; these organisms probably do not bear any
causal relation to the diphtheria itself, but appear to be
accidental accompaniments which may give rise to
secondary complications either local or general. If
these cocci are cultivated on nutrient jelly, small light
greyish drops, as clear as water, are noticed in about
three days, their borders showing with a low power small
curly lines composed of chains of cocci. The chains
may contain up to 100 individuals, some of which attract
attention by their size, and at times the whole of the
chain consists only of these large cocci ; on closer ex-
amination indications of transverse division can be seen
in these organisms. — On subcutaneous inoculation or
injection of the cultivations into mice a considerable
number, more than half, of the animals usually die ;
streptococci are found in the spleen and in other organs.
After inoculation on the ear an erysipelatoid inflamma-
tion occurs in the case of rabbits; if, however, cultivations
are injected into the veins, affections of the joints occur
in 4 — 6 days, the joints becoming filled with pus con-
taining streptococci, and the disease in most cases
gradually ending in the death of the animals. Similar
joint affections occur in connection with the streptococci
already described, but here only as part of a general

MICBOCOCCI PATHOGENIC IN MAN. 195

infection running a rapid course. Further, after injection
of erysipelas cultivations Loeffler obtained joint affections
in two cases, but the author was unable to confirm this
result in a larger number of experiments.

Heubner and Bahrdt have recently found similar
streptococci in the pus in a fatal case of scarlatina, accom-
panied by suppuration of joints. They were able to show
that the cocci entered the jugular vein through a purulent
canal extending from the original diphtheritic affection
of the tonsil, and then, just as in Loeffler's experiments,
set up the suppurative inflammations of the joints.*

Streptococcus septicus,

Although this organism has not as yet been observed
in man it may be mentioned here, because in its whole
behaviour it shows a great resemblance with the other
streptococci. — Strept. sept, was repeatedly found by
Nicolaier, and afterwards by Guarneri, in impure earth. f
It cannot be distinguished microscopically from the other
streptococci, but it has not such a marked tendency to
form chains under all circumstances ; it occurs especially
in the tissues, and usually in the form of diplococcL
Where, however, masses are present, which are com-
posed of larger balls of the organisms, the chain-like
arrangement becomes distinctly marked, especially at
the borders, and it is also well developed in cultivations
in hanging drops, on plates, &c. — The colonies on gela-
tine grow even more slowly than those of the other
streptococci — not till after 3 or 4 days do they become
evident as fine points; in puncture cultivations also
distinct colonies are first seen on the 5th or 6th day.
Mice die without exception in 48 — 72 hours after sub-
cutaneous inoculation of minimal quantities of a cultiva-
tion. During the last 24 hours a distinct motor and
sensory paralysis of the hinder extremities is present.
On post-mortem examination large numbers of diplo-
cocci are found in the blood and organs, at times in large
masses, which completely fill the vessels. Inoculations

* Berl Tclin. Woch., 1884, No. 44.
f Gottinger hygien. Institut.

196

CLASSIFICATION OF THE MICRO-ORGANISMS.

on other mice succeed with the minutest quantities of
blood or splenic juice. In rabbits after inoculation on
the ear there occurs in the first instance a local redness,
then a general disease, and death after 2 or 3 days.
In the internal organs a marked accumulation of micro-
cocci is found everywhere, at times leading to plugging
of the vessels and the formation of necrotic foci. This
tendency to the formation of foci leads in the case of
rabbits to transmission of the coccus to the foetus, as
shown by Oberdiek ; * nevertheless in the latter there
are always markedly fewer micrococci, because the lesion
of the placental tissue evidently occurs only towards the
termination of the life of the mother.

Comparison
and distinc-
tion of the
various
streptococci.

In connection with the species of streptococci just
described we meet with the striking fact that five
organisms, scarcely distinguishable from each other
microscopically or by cultivation, are so markedly different
in their action on man and the lower animals. The
resemblances on the one hand, and the differences in
pathogenic effect on the other, have been accurately
ascertained by Guarneri in a special series of experi-
ments in which particular attention was paid to any
possible deception or confusion. More especially any
possible immunity of the animals as the cause of the
inefficiency of the pyogenic and erysipelas streptococci
was excluded, because the same animals which had
resisted one or several inoculations with the Strept.
pyog. without effect, at once died from inoculation with
Strept. pyog. malign us.

From this result we may assume that streptococci of
very different virulence occur in the various infective
diseases of wounds in man, and that the symptoms and
the result of the disease caused by streptococci are due
not only to the mode of invasion, or the functions of the
organs attacked, but also to the specific characters of
the organism. In order to recognise the latter it is

* G6tting2r hygien. Institut.

MICBOCOCCI PATHOGENIC IN MAN. 197

evident from what has gone before that the character-
istics observable by the microscope or by cultivation are
not sufficient, but that experiments on animals must
also be made, and in many cases even these are not
sufficient for a diagnosis.

Tn a series of diseases in man streptococci have been found,
but we have not been able to decide whether we have to do
with specific organisms peculiar to the disease in question,
or with one of the forms of streptococci previously mentioned.
Thus in—

Endocarditis ulcerosa. — The masses of micrococci
found in the vessels show for the most part a chain-like
arrangement of the cocci ; nevertheless staphylococci
may present similar appearances in the tissues, and in
one cultivation experiment with the micrococci of endo-
carditis only staphylococci grew (Wysokowitsch). Accord-

Fig. 46. — Endocarditis ulcerosa X 700.
Section from the cardiac muscle. (After a photograph by Koch.)

ing to the author's experiments referred to above, it is
at all events unnecessary to assume the existence of a
specific organism in order to explain the origin of an
endocarditis. Further, in many cases of pyaemia and
pyaemic metastasis, also in puerperal metritis as well
as in cerebrospinal meningitis, streptococci have been

198 CLASSIFICATION OF THE MICRO-OBGANISMS.

demonstrated microscopically, and have been assumed to
be the causal agents of the disease (Lit., pp. 15 and 35).

Micrococcus gonorrhoea.

Gonorrhoea Observed by Neisser in 1879 in gonorrhoeal secretions,

and later termed gonococcus ; cocci which almost

Morphological always occur in the form of diplococci. The elongated

peculiarities. , -,,,., ... , . . . •,

body of the diplococcus in stained specimens shows in
the middle a clear line (best seen in preparations stained
with fuchsin), which with the highest powers appears
as a distinct partition ; this line divides the coccus
into two halves, and gives it the roll (biscuit) form. As
a rule the two halves are not true half circles ; at
times a slight concavity is present on the opposed and
flattened surfaces of the hemispheres. Cocci not under-
going division are only exceptionally seen. The average

length of the diplococcus
is about 1*25 /z. ; its long
diameter varies between 0'8
and 1*6 /*., its transverse
diameter between 0*6 and
0'8 /j,. — The cocci in the
Fig. 47.— Micrococciis of gonorrhoea ffonorrhceal secretion lie

X 800. (After Buinm.) , . a . ,, ,,

a, free cocci. ?hie% °n °.r m the PUS Cells

b, cocci in pus cells. in small irregular heaps.

o, epithelial cell containing cocci. mi

They are not in contact

with the cell nuclei, but that they really lie in the proto-
plasm of the cells appears certain from the fact that in
carefully prepared specimens they do not extend beyond
the margin of the protoplasm ; a similar inclusion in the
protoplasm is not observed in the case of the other non-
specific rnicrococci, which are also often present in
considerable numbers in gonorrhoeal secretion. The
number of cells containing cocci is greatest not so much
in the early period after infection, so long as the
secretion still remains serous, as in the later suppurative
stage of the gonorrhoea. — The cocci become decolourised
in Gram's method.

cultivation In cultivation experiments with the gonorrhoeal cocci,
experiments. ^e saprophytic organisms present in the secretion have

MICROCOCCI PATHOGENIC IN MAN. 199

often led to mistakes. By the elaborate researches of
Bumm it seems to be definitely ascertained that no
growth of the specific cocci occurs on nutrient jelly or
on the other ordinary nutritive substrata, or at the
temperature of the room. Positive results under these
circumstances have always been due to saprophytes
morphologically very similar to the gonorrhoea! cocci.
According to Leistikow and Loefiler blood serum
gelatine is a very suitable soil for the gonorrhceal cocci ;
according to Krause and Bumni solidified blood serum
is the best. Bumm obtained the best cultivations with
moderately firm blood serum, the surface of which was
protected from drying by placing the tubes in a moist
chamber, and at about 32° C. If he inoculated the
secretion containing cocci on such blood serum, a fine
layer spread over the surface from several spots along
the inoculation stroke ; this layer attained a breadth of
1 — 2 mm., ultimately presented the appearance of a
very thin greyish yellow layer with moist smooth sur-
face, and then ceased to grow, and was found to consist
of closely packed masses of cocci. Further cultivations
can be carried on through several generations when the
reinoculations are made as early as possible. The
growth is always very imperfect ; the line of inoculation
increases in breadth by scarcely 1 mm. in the course of
a day, and the organisms frequently die without any
apparent reason.

Animals have proved completely immune to the inoculation on
gonorrhceal cocci. In dogs, rabbits, horses, monkeys, ammalH-
&c., neither the fresh secretion, nor cultivations inocu-
lated on the conjunctival or urethral mucous membrane
have caused inflammation. On the other hand, the On man.
attempt has been made in two cases by inoculation of
cultivations on healthy human beings to demonstrate
the etiological role of the cocci in gonorrhoea. In
the first case Bockhart introduced a large quantity
of a cultivation in peptonised nutrient jelly into the
urethra of a lunatic who died some time afterwards from
an accidentally acquired pneumonia ; during life typical
gonorrhoea had developed, the secretion being full of

200 CLASSIFICATION OF THE MICEO-ORGANISMS.

cocci, and in the sections through the urethral mucous
membrane numerous cells filled with cocci were found.
This case is not quite free from objection, because later
experiments have shown that no growth of the cocci
occurs on nutrient gelatine ; perhaps, therefore, the
positive result was obtained by cocci which had not
grown in the cultivation but had been carried over
in the inoculations, and had remained alive; this is
not at all improbable, because large quantities were
employed in the inoculation from the pus, and in
the subsequent reinoculations, and also because the
fourth generation was employed for the infection ex-
periment. A second inoculation experiment was made
by Bumm on the healthy urethral mucous membrane
of a woman, and in like manner with a positive
result ; the second generation of a cultivation on blood
serum was employed. Here also, in spite of the
fact that pus cells could not be found in the cultiva-
tion on microscopical examination, the objection is
possible that perhaps cocci were carried over from the
secretion, especially as the first inoculation on the
artificial soil was always made with relatively large
quantities.*

Occurrence of The occurrence of the gonorrhoea coccus is, according
coccus!™ a to the opinion of all trustworthy observers who are ac-
quainted with the saprophytic forms similar to the gono-
coccus, limited to gonorrhoeal affections of the urethra
or bladder, of the cervix uteri, &c., and to the specific
blennorrhoea of the conjunctiva. The characteristic
cocci were also found in the purulent effusion into a
knee joint in a case of gonorrhreal inflammation of the
joint (Petrone and Kammerer).

Micrococcus sulflavus.
(Yellowish-white diplococcus of Bumm.)

Micrococcus Similar to the foregoing, frequently observed in the
similar to the lochia and in vaginal secretions, and perhaps also

gonorrhoea

coccus. * Bumm has since obtained a successful result by inoculation of a

twentieth cultivation.

MICROCOCCI PATHOGENIC IN MAN. 201

pathogenic for man. A diplococcus 0*5 — 1'5 p.. in
diameter ; it shows a central division, and is composed
of two hemispheres like the gonococcus ; in contrast to
that organism M. subflavus retains the aniline dye after
treatment with Gram's iodine solution. Twenty-four
hours after inoculation on nutrient jelly whitish points
develop and grow to whitish-grey, later yellowish, and
finally ochre-coloured confluent masses ; after a few
days nutrient jelly and blood serum become liquid in
the neighbourhood of the cultivation. — Inoculation ex-
periments on various mucous membranes susceptible to
the gonorrhoeal contagium was without result. On the
other hand, according to Bumm, an abscess, varying from
the size of a pigeon's egg to that of a man's fist, and con-
taining numerous diplococci, follows the injection of these
bacteria into the subcutaneous cellular tissue in man.

Besides the lochia this organism was also found in
the urine in some cases of catarrh of the bladder and
also in the contents of the bullae in pemphigus neonat.,
and in the pus of a mammary abscess. Further,
Friinkel has found the same diplococcus, along with
another coccus to be mentioned under the saprophytes,
in the vaginal secretion in a large number of children
suffering from colpitis, but not infected with gonorrhoea.

Micrococci in Zoonotic Finger Erysipeloid.

Cocci were found by Kosenbach* in a mild disease of
the skin, not associated with general disturbance, which
is characterised by a bluish brown red, sharply defined
infiltration of the skin of some fingers and of the hand
very similar to erysipelas. These organisms formed,
when inoculated on agar, very delicate and elegant
colonies which were scarcely visible without magnifica-
tion. Inoculation of the cultivations on the upper arm
of a healthy man reproduced the affection.

Corduaf has studied 127 cases of the same disease.

* Mikroorganismen bei den Wundlnfectionskrankheiten. Wiesbaden,
1S84, p. 117.
f Deulsche medicin. Wochenschrift, 1885, No. 33.

202 CLASSIFICATION OF THE MICRO-ORGANISMS.

The individuals chiefly affected were those who had to
do with animals and animal tissues, such as tanners
butchers, &c. Cordua was able to cultivate cocci from
the affected portions of skin, and they formed in 24 — 86
hours on agar at 36° C. luxuriant chalk-white colonies,
with slightly facetted margins. Inoculations on animals
were without result, but here, also, he was successful in
setting up the affection on his own arm from a cultiva-
tion. Probably Kosenbach and Cordua have been dealing
with cultivations of the same organism which presented
different appearances only in consequence of differences
in the nutritive substrata. Further investigations must
be awaited.

Imperfectly
known patho-
genic micro-
cocci.

Micrococci have also been described as causal exciting
agents in numerous other diseases in man, but they have
been demonstrated either by microscopical investigation
alone, or the infective and cultivation experiments are
not free from objection, and therefore further con-
firmation appears to be necessary. To these belong * —

Variola. — Cohn, Weigert, Koch, and others, found
micrococci in the pustules and in various internal organs
in persons who died of smallpox. Cultivations have not
yet been made.

Vaccinia. — In the lymph in the vesicles micrococci
have been frequently observed; cultivations of cocci
have also been repeatedly obtained from the lymph, but
all the micro-organisms as yet cultivated are evidently
only impurities for the most part of a saprophytic
character, as a vaccine pustule has never been produced
by inoculation of the cultivations. The recent cultiva-
tion experiments by Wolff do not seem to have given
a better result.

Scarlatina, Measles. — Micrococci found, but of no
importance (see Lit., p. 35).

Diphtheria. — In the former investigations by Klebs,
Oertel, and others, these authors evidently did not work

As to the Micrococcus pneumonice see under " bacilli."

MICBOCOCCI PATHOGENIC IN MAN. 203

with specific organisms. As to Loeffler's streptococcus
see above (p. 194) ; as to bacilli in diphtheria see below.

Cerebrospinal meningitis. — Leyden, and more recently
Leichtenstern, have found cocci in the purulent exudation
on the pia mater; these were sometimes enclosed in
white blood cells, sometimes they lay outside them.

Influenza. — According to Seifert numerous micrococci
1'5 — 2 fi. in length and 1 /*. in breadth, are embedded
in the tenacious mucus composing the greyish-white
clumps present in the sputum and in the nasal
secretion at the height of the fever. They are mostly
arranged in long chains ; their numbers markedly
diminish as the number of cells in the secretion
increases. In control examinations of the secretion in
bronchitis, &c., the cocci were not found.

Ozcena. — Frtinkel found various micrococci in the
secretion, Loewenberg chiefly only one kind. The
cultivation and infection experiments do not sufficiently
establish their significance.

Cocci have been demonstrated in Hamophilia neona-
torium, and in acute yellow atrophy of the liver.

In yellow fever Domingos Freire has found a micro-
organism which he terms Cryptococcus xanthogenicus
and which he regards as the cause of that disease ; the
observation, however, is evidently based on gross errors.
Cornil and Babes recently found in one case that the
capillaries of various organs contained long chains of
diplococci, but they could not find these organisms in
five cases investigated subsequently. As to bacilli in
yellow fever see below.

In trachoma of the conjunctiva Sattler has found cocci
in the secretion and in the trachoma nodules ; he was
able to cultivate these organisms on nutrient jelly, and
when inoculated on the normal conjunctiva they set up
vesicular-like granules without pathological secretion or
subjective symptoms. We must await repetition of
these experiments with more typical results before con-
cluding that these cocci are the causal agents.

In area Celsi, Buchner, and later von Sehlen,have found
micrococci somewhat less than 1 /u. in diameter, and

£04 CLASSIFICATION OF THE MICRO-ORGANISMS.

have cultivated them in nutrient jelly. Michelson has
however asserted that von Sehlen's case was not one of
true area Celsi (see Lit., p. 37). .

Rindfleisch found numerous plugs of streptococci in
the cutaneous capillaries in a case of mycosis fungoides
or grannloma fungoides (spongy nodular out-growths
of the skin consisting of granulation tissue) ; these
organisms stain well with Gram's method. Auspitz
has also seen cocci in a similar case.

B. MICROCOCCI PATHOGENIC IN THE LOWER ANIMALS.

Micrococci have been stated to be the cause of some
important infective diseases of domestic animals (mam-
malia), nevertheless the proofs as yet brought forward
are insufficient.

Rinderpest. — In Russia, and in some parts of Austria,
a widespread epidemic contagious disease exists among
cattle ; it is characterised by general prostration, in-
creased secretions, fluid, slimy, or bloody stools, and
quickly terminates in death. On post-mortem exami-
nation the appearances are those of an intense gastro-
enteritis with hypertrophy or ulceration of the solitary
follicles, and of Peyer's patches. Sernmer asserts that
he has cultivated micrococci from the dead body, and
that he has caused the disease by inoculation of these
organisms. These investigations are however open to
the same objections as the other bacteriological work of
the same author.

Pleuropneumonia in cattle (ptripneumonie contagieuse
du gros letail). An epidemic pleuropneumonia of cattle
which causes death in a fourth of the cases. Poels and
Nolen have isolated cocci from the pulmonary exudation
which resemble Friedlaender's pneumonia bacteria mor-
phologically, and in their growth in cultivations. Cornil
and Babes found a mixture of various bacteria in the exu-
dation, as to the special etiological significance of which
nothing has as yet been settled. The fluid flowing from

MICROCOCCI PATHOGENIC IN THE LOWER ANIMALS. 205

the cut hepatised lung has heen frequently employed for
protective inoculations ; it is injected subcutaneously
into the tail, and causes at the most a local affection, and
after this has passed off immunity is said to be attained.

Swine erysipelas (pig typhoid, &c.). Pasteur and
Thuillier have found micrococci in the blood and in the
exudations, and have ascribed io them a causal signifi-
cance. Loeffler and Schiitz, Lydtin and Schottelius
have, however, described bacilli as the true causal agents
of this disease (see later).

A number of well characterised pathogenic micrococci
have been observed in various of the animals ordinarily
employed for experiment. To these belong, besides the
above-mentioned staphylococcus, which can be inoculated
on lower animals with success, streptococcus malignus
and septicus.

Micrococcus tetragenus.

First described by Gaffky.* It is not uncommonly Micrococcus
found in human sputum, and is especially observed
in the sputum and in the walls of the cavities in cases of
pulmonary tuberculosis. Micrococci about 1 /*.. or Microscopic
more in diameter, dividing into four individuals which appea
remain united by a gelatinous envelope. In cultivations
we find some large spherical cells undergoing division,
but the greatest number consist of cells in which the
division has been completed. The round gelatinous
envelope stains faintly, the microccoci strongly with
aniline dyes ; the colour is retained in Gram's method ;
the appearance recalls that of sarcina, but the division
in the third plane and the formation of many-celled
packets is absent. — On gelatine plates M. tetragenus Cultivations,
forms in 24 — 48 hours small white points which under
a low power present the appearance of circular or citron-
shaped yellow masses, with a granular, mulberry-like
surface, and regular, but somewhat rough, jagged

* "Klinische, experimentelle u. botanische Studien iiber die Be-
deutung des Torfmulls als Verbandmittel." Von Dr. Neuber, Dr.
Gaffky, u. Dr. Prahl, v. Langenbeck's Arch./. Chir., vol. 28, Heft 3.

206

CLASSIFICATION OF THE MICBO-ORGANISMS.

Experiments
on animals.

borders. When they have reached the surface they
form white raised thick drops on the gelatine 1 — 2 mm.
in diameter. In the inoculation puncture the colonies

Fig. 48. — Micrococcus tetragenus. Section of lung X 800.

become confluent, so that a thick white gelatinous mass
is formed along the line of puncture, and fills any
cracks or cavities in connection with it ; on the surface
a thick layer 4 — 5 mm. in breadth is formed.

The minutest quantity of the cultivation inoculated
subcutaneously into white mice causes in all cases a
fatal disease. The first 2 days
pass by without noticeable symp-
toms ; then the animals become
still and somnolent, and after
8 — 6 days death occurs. The cocci
are only present in the interior
of the blood vessels ; in the blood
of the heart they are relatively
few in number, they are present
in larger numbers in the splenic
•juice and in sections of the lungs,

Fig. 49.— Micrococcus tetra- J.

genus. Section of, spleen in the glomeruli of the kidneys,

x 600' in the liver, &c. Grey house

mice are almost without [exception immune against M.

MICROCOCCI PATHOGENIC IN THE LOWER ANIMALS. 207

tetragenus; guinea-pigs show either local abscesses
or septicaemia; rabbits and dogs are unaffected by
large quantities injected subcutaneously or into tbe
veins. Whether in man the presence of M. tetragenus in
the tuberculous lungs is accompanied by any secondary
injurious results must be ascertained by further investi-
gations. In the meantime M. tetragenus is of import-
ance to us as it is a micro-organism admirably adapted
for experiments on account of its morphological pecu-
liarities and of the ease with which it can be cultivated.

The following are imperfectly known: Streptococcus Organism of a

. AT T-II ,1 i disease of

permciosus psittacorum. According to Ebertn and parrots.
Wolff parrots imported into Europe die in large numbers
from a disease in which nodules are formed on the sur-
face of the lungs, spleen, kidneys, &c. Cocci of medium
size with a tendency to the formation of chains are found
in the vessels, in the nodules, and in the blood of the
heart.

Streptococcus Charrin. — Found by Charrin* in the Chamn's
bodies of rabbits which had died of anthrax. Oval micro-
cocci 1 to 2 p. in diameter, with a tendency to form
chains composed of as many as twenty cocci. They are
present in large numbers in the vessels of all the organs.
The micrococcus kills rabbits within eighteen to forty-
eight hours after subcutaneous inoculation. On post-
mortem examination we find great swelling of the spleen
and oedema at the seat of injection. Besides rabbits,
sparrows and cats are also susceptible, the latter, how-
ever, not always ; dogs and fowls are immune. This
septicaemia is termed " septicemie consecutive au char-
bon." It is probably identical with Koch's coccal sepsis
(p. 211).

Streptococcus lombycis (Mikrozyma bombycis, Be- Silkworm
champ.) Oval cells at most 1*5 /*. in diameter, single or
united in pairs or chains of 4 — 8, or even longer straight
or curved chains ; causes the lethargy (flacherie, flacci- Lethargy.
dezza, maladie de morts-blancs) of the silkworms which
appeared about 15 years ago, and since then has broken
out with great violence from time to time.

* Societe de biologie, Seance du 2 Aout, 1884.

208 CLASSIFICATION OF THE MICRO-ORGANISMS.

The living animal shows diminished appetite, and becomes

languid ; soon after death the bodies become soft and almost

fluid ; after 24 — 48 hours they present a dark colour, and

become filled with gases and blackish brown putrid fluid.

The disease appears to develop "spontaneously" under

unfavourable hygienic conditions^-bad ventilation and food,

&c. ; it is also propagated by infection. The disease can be

set up in healthy animals by feeding them with dust from

affected localities. In the digestive tube of the diseased and

dead animals, especially in the juice of the stomach, these

Oo o micrococci are constantly present in

no00 o large numbers, and other bacteria also

ooo0o °°0o^ appear shortly before death. Never-

^oo0oc*so theless there is no proof that all the

0 \ morbid symptoms can be explained by

0 %ooc °* the distribution of the micrococci in the

Fig. 50.— Micrococcus bod^' or that the minutest number of

bombycis (afterCohn) the isolated organisms can induce the

x 60°- disease ; there is, therefore, a possibility

that other bacteria more difficult to demonstrate are the true

exciting agents of the disease.

Febrine Nosema bombycis (Micrococcus ovatus, Panhistophyton ovatum,

corpuscules du ver a sole), the cause of the pebrine (Oattine,

Fleckenkrankheit, maladie des corpuscules) of the silkworms

a may be included here, although

0""'c\ o from the size and form of the

* *& %&- b organismsJ as wel1 as from the

^ 0 ?• ® Q> imperfect knowledge of their

a Q °0 ^ 8 b developmental history, we are

Q ° still doubtful as to their proper

Fig. 51.— Nosema bombycis Place- In the blood and in a11

X 500. the organs of the diseased worms

a, Nosema cells. we find highly refracting oval cells,

' b, urates which are usually 3^ long< 2 ^ broad; for the

present in the prepara- . ° ^ . ' .

tions. (After Duclaux.) most part isolated, at times united

in pairs or masses. They were

first discovered by Cornalia, and subsequently described by
Lebert, Nageli, and Pasteur. Recently Metschiiikoft' has
supported the supposition formerly entertained, that the
exciting agents of pebrine belong to the psorospermese.

The disease is characterised by the appearance of blackish
patches on the skin of the caterpillars. At the same time the
appetite diminishes and the worms become more slender and
watery ; the silk organ swells up in a garland form, becomes
opaque, and the diseased worms furnish no coccooiis, or only
very weak ones ; finally, they die after a short time. The
whole organs then appear to be infiltrated with the " micro-

MICEOCOCCJ PATHOGENIC IN THE LOWEE ANIMALS. 209

cocci"; the organisms are also found iiithe eggs of the butter-
flies, and by means of these infected eggs the hereditary
transmission and the continuance of the disease is provided
for ; for otherwise, on account of the slight resisting power of
the micrococci, they would be in danger of disappearing.
Pasteur has demonstrated experimentally that the disease
may be transmitted by micrococci contained in the food, or
by their penetration through injured parts of the skin, and
that currents of air, handling by the breeder, &c., may lead to
the spread of the infective germs. — As prophylactic means
the plan introduced by Pasteur is now generally adopted ;
the butterflies which are laying eggs are separated in pairs,
and after copulation and the laying of the eggs, are examined
as to the presence of the characteristic "micrococci." If
the latter are found the eggs are destroyed, and not employed
for breeding.

To this group also belong some infective wound dis- Koch's micro-

, , . , . , . , , p ,, cocci in the

eases in animals which were investigated as fully as infective

possible by Koch by microscopical observation at a time Jgea!seS of the
when no trustworthy methods of cultivation were known, lower animals.

Micrococcus of Progressive Necrosis of tissue in Mice. —
Round cells, 0*5 /*. in diameter,usuallyarrangedin beautiful
and regular chains, at times
massed together in thick
groups (fig. 52), causes ne-
crosis of the tissue ; as far
as the micrococci reack no
blood or connective tissue
cells remain intact, and even " .......

the cartilage cells are de-

stroyed. The gangrene ex- Fig. 52.— Micrpcocci of progressive

tends from the point of SSSf"

inoculation, and SOOn causes «, cells of the cartilage of the ear.
death (in about 3 days); ^ ^hain forming micrococci.

the blood and internal organs remain free from micro-
cocci. From their behaviour we must assume that a
soluble noxious material is produced by the vegetation of
the cocci. — The disease was obtained by Koch by inocula-
tion of putrid material on the ear of mice ; at the same
time, however, bacilli which caused septicaemia were always
inoculated, and led to the death of the animal ; it was
not till field mice, which are immune against the

14

210 CLASSIFICATION OF THE MICRO-ORGANISMS.

bacillar septicaemia, were inoculated, that the course of
the disease could -be observed undisturbed by the pre-
sence of other bacteria.

Micrococcus of Progressive Abscess Formation in
Rabbits. — Minute cells, only about 0'15 p. in diameter,
generally in thick cloud-like zooglsea masses (fig. 53).
It was obtained by injection of putrefying blood into

Fig. 53. — Micrococcus of progressive abscess formation in rabbits
(after Koch) X 700.

Border of a cheesy abscess : —

er, cloud-like masses of zooglsea.

b, smaller colonies of micrococci.

c, nuclei.

rabbits ; an extensive abscess formed at the seat of
injection, and caused the death of the animals in about
12 days. No bacteria are present in the blood ; a finely
granular mass is found in the cheesy contents of the
abscess; the wall of the abscess is formed of a thin
layer of micrococci united in dense zooglsea masses ;
towards the interior of the abscess the zooglaea appears
to degenerate and die. Nevertheless the contents of
the abscess are infective, and set up the same disease
in healthy rabbits.

Micrococcus of Pycemia in Rabbits. — Round cells,
0'25 p. in diameter, for the most part single or united
in pairs ; they tend to surround and enclose the blood
corpuscles in a characteristic manner (fig. 54). The
disease in question was obtained by injection of fluid
used for maceration ; on post-mortem examination there
was great infiltration around the seat of injection, peri-

MICROCOCCI PATHOGENIC IN THE LOWER ANIMALS. 211

tonitis, metastatic deposits in the lungs and liver — in
short the appearances of pyaemia. In the capillaries of
all the organs investigated dense micrococcal masses,
with enclosed blood corpuscles,
were found ; likewise in the me-
tastatic deposits, where they had
passed out of the vessels and at-
tacked the neighbouring tissues.
In the blood of the heart and of
the larger vessels numerous micro-
cocci were likewise present, but,
in consequence of the numerous
thrombi, they were not so numer-
ous as in other septicaemic diseases.

TT ,,, , , .. . f . n Fig. 54.— Micrococcus of

Healthy rabbits were infected sue- pysemia in rabbits
cessfully by inoculation of blood ir C^ter Koch) x TOO.

J J Vessel from the cortical

from the heart, &c., but larger

part of the kidney : —
u. nuclei of the vascular

wall.
b, micrococci.

doses (1 — 3 drops) caused death

more rapidly (40 hours) than

small quantities (TV) drop), on account of the relatively

small numbers of cocci in the circulating blood.

Micrococcus of Septiccemia in Rabbits (compare above
Streptococcus Charrin). — Oval cells, 0'8 — 1*0 /*. in
greatest diameter. They do not cause coagulation in
the blood, and never enclose the blood corpuscles, but

Fig. 55.— Micrococcus of septicaemia in rabbits (after Koch) X 7CO.

Part of a glomerulus : —

At a the capillary vessel with micrococci.

push them to one side (fig. 55). The disease was
obtained by Koch by injection of meat infusion ; after

212 CLASSIFICATION OF THE MICRO-ORGANISMS.

death slight oedema was found at the seat of injection,
small extravasations of blood, marked enlargement of
the spleen; no embolic processes, no peritonitis. Masses
of micrococci were found obstructing the capillaries of
various organs, more particularly in the glomeruli of the
kidneys. Inoculation of the blood of the heart trans-
mitted the disease to rabbits and mice, but only when
considerable quantities (2—10 drops) were used.

C. SAPROPHYTIC MICROCOCCI.

Some micrococci set up fermentations, or peculiar
decomposition products, when growing in suitable media.
To these belong : —

Micrococcus Urea.

Leube's Micrococci 0'8 — I'D p. in diameter, often grouped

micrococcus together in the form of diplococci and tetrads, fre-
quently also in longer chains. In plate cultivations,
according to Leube, white mother- of-pearl-like spots
about the size of a hemp-seed, with smooth surfaces
and sharply defined margins, are formed on the gelatine
within 24 hours. In 10 days the colonies have attained
the size of about a 20 pfennig piece (about the size
of a sixpenny piece). They project somewhat above the
surface, and resemble a drop of stearine which has fallen
on the gelatine. The circular colony gradually breaks up
into several portions divided by fissures, and each of these
forms a zooglasa, which gradually increases in size. —
Under a low power the border of the colony
appears finely granular ; further towards

19 oSb*®0* ^C centre ** *s completety opaque.— The
Fig 56 —Micro- gelatine is not liquefied. Along a punc-
coccus ureae x ture in gelatine the cocci form a thin
tenacious thread. In old cultivations a
heavy paste-like smell is developed.

If a small quantity of the cultivation is introduced
into urine, or into a solution of urea, an energetic decom-
position of urea into ammonium carbonate occurs.
Pasteur and van Tieghem regarded micrococci as the

SAPROPHYTIC MICROCOCCI. 213

active causes of this dehydration, and gave to this
organism the name of M. urea; Leube has recently
shown that a large number of bacteria (such as sarcinae
from the lungs, and several bacilli which are found in
ammoniacal urine— see under " bacilli") can set up
the same decomposition with, to some extent, the same
energy. In the author's laboratory another coccus was
isolated from decomposing urine, which, like the preced-
ing, causes an energetic fermentation of urea, but shows
certain differences in the characters of growth ; more
especially it liquefies the gelatine.

Micrococcus urece liquefaciens.

Spherical cells, 1*25 — 2 //. in diameter, single or Amicrocpccus
forming chains of 3 — 10 individuals or irregular groups. Hq^fi^the
On gelatine plates they form in two days small white gelatine,
points, which under a low power appear as dark-
grey circular discs, with sharply defined borders.
When they reach the surface the colonies become
markedly larger; when magnified 80 times they have
the appearance of dis^ss of a yellowish-brown colour,
which often contain in their middle a dark nucleus —
the deeper portion of the colony; the surface of the
discs is distinctly granular ; the borders gradually
assume a wavy character, at the same time gradual
liquefaction of the gelatine occurs. In the puncture
cultivation a white confluent layer is at first formed along
the needle track, then liquefaction of the gelatine soon
occurs, and extends to the wall of the glass ; finally, the
half or the greater portion of the tube becomes filled with
a whitish turbid fluid, at the bottom of which a thick
whitish-yellow deposit lies.

It might appear doubtful which of the two cocci described
above was the one referred to in the observations published
formerly at a time when a definite isolation of the individual
species was not possible. Nevertheless, the circumstance
that in Leube's elaborate experiments the organism first
described was chiefly met with in the great majority of cases, Biological
is in favour of the view that former observers were working properties of
with it. — From the numerous contributions to the biology

214 CLASSIFICATION OF THE MICRO-ORGANISMS.

of tliis organism which have been furnished by Pasteur
van Tieghem, Musculus, v. Jaksch, and others, we learn that
the alkaline reaction which occurs in no way interferes with
the development of the organism. The fermentation con-
tinues till about 13 per cent, of carbonate of ammonia has
been formed. Artificially prepared solutions of urea, to
which the necessary salts have been added, are rapidly
decomposed in the same manner. According to v. Jaksch
the best artificial cultivating fluid consists of 3 grammes of
urea, 5 grms. of tartrate of potash and soda, O12 grms. of
monophosphate of potash, O06 grms. of magnesium sulphate,
dissolved in 1,000 ccm. of water. The best temperature for
development lies between 30° and 33° C. — Musculus has
attempted to show that the ferment of the ammoniacal fer-
mentation can be separated from the micrococci which pro-
duce it, just as the inverting ferment can be separated from
the yeast. By precipitation of urine containing much mucus
from cases of catarrh of the bladder by means of absolute
alcohol, and subsequently drying and pulverising the pre-
cipitate, Musculus obtained a substance soluble in water
which converts urea very energetically into carbonate of
ammonia. Leube was able, nevertheless, to show that pure
cultivations of Microc. ureee filtered through plaster cells are
inactive, that thus the ferment whidh was isolated is not
produced by the organisms, but has perhaps some other
source of origin.

According to v. Jaksch and Billet the micrococcus shows
a great variety of vegetative forms in that it can also give
rise to rod-shaped forms, which again become changed into
chains of cocci. These observations were made on cultiva-
tions in which there was no guarantee for their purity, and
could not be confirmed either by Leube or in the author's
laboratory.

Leuconostoc mcsenterioides.

Recognised by Cienkowski and van Tieghein as the
cause of the so-called frog-spawn fermentation (Froscli-
laichgahrung) of the beet juice and molasses in sugar
factories. Forms chains of cocci, which are surrounded
by a thick tenacious gelatinous envelope ; large compact
gelatinous masses ultimately arise by union of numerous
chains. When the nutritive materials are becoming
exhausted, the majority of the cells die ; some however,
which appear to be larger, with thicker walls and more

SAPROPHYTIC MICROCOCCI.

215

highly refracting, remain as arthrospores, and develop
in fresh nutritive solutions to new coccus chains.

The organism grows on the surface of carrots or beet-
root in the form of thick massive gelatinous cakes, of
cartilaginous consistence. It also flourishes in solutions
of grape and cane sugar, to which nitrates and phos-
phates have been added. Cane sugar is in the first
place converted into glucose, by a ferment formed by the

Fig. 57.

Leuconostoc mesenterioides. (After Zopf .)

1, 2, 3, 4. Successive stages of division of the cocci and formation of
the gelatinous material. 5. A collection of small zooglaea. 6. Section
through an older zooglaea mass, containing fairly long torula-like
threads. 7. Chain of cocci, showing spores here and there, the spores
being larger than the cocci.

organisms. When the organisms develop luxuriantly,
enormous quantities of sugar can be assimilated in a
relatively short time and converted into the substance of
the organisms, chiefly into the gelatinous material. This
material is described by Scheibler as " dextran," and the
whole process, which may be very hurtful to the manufac-
turers of sugar, is included under the term " dextran fer-
mentation." Nothing is as yet known as to the growth
of the organism on the ordinary solid nutritive media.

216 CLASSIFICATION OF THE MICRO-ORGANISMS.

Micrococcus viscosus.

Pasteur* has found a micrococcus which seems to be
the cause of viscosity in wine (vinfilant) ; the diameter
of this organism is only 0*2 p., and it is arranged chiefly
in the form of chains. It grows in the most various
saccharine fluids, and converts them into a viscoid and
tenacious mass ; a form of gum is constantly developed,
to which Bechampf has given the name of viscose.
Nothing is definitely known as to the morphology and
characteristics on cultivation of this organism. Cocci
have been found by Schmidt-Miilheim J in tenacious
milk, which were possibly the cause of this abnormality.
The cocci measure about 1 /*., and often lie in chains
like strings of beads, containing 15 or more individuals.
The decomposition does not appear to be the same as in
the case of the viscous wine, for no mannite and no car-
bonic acid are formed ; the mucus is closely allied to
that of plants. Cultivation experiments are wanting.

Micrococcus Pfliigeri.
(Bacterium Pfliigeri, Ludwig.)

Micrococci | to 1 p. in diameter, for the most part in
zooglasa masses. They were first observed by Pfliiger,
later by Lassar, Ludwig, and Niie^sch, on phosphorescent
meat (from slaughtered animals, fish, &c.), the surface
of which was covered with a luminous slime. The
cocci are also saift to grow on boiled white of egg and
potatoes, on which they also develop their peculiar
luminosity. Further statements as to the conditions
of cultivation, &c., are wanting.

Micrococcus fcetidus.

Found by Kosenbach in carious teeth. Very small
oval somewhat irregular cocci which stain badly with
aniline dyes. They could not be cultivated in stroke
cultivations on agar jelly, but on the other hand grew

* Bull, de la Soc. Ch., 1861, 30.

f Compt. rend., T. 93.

I Pfliiger's Archiv, 1882, vol. 27, p. 490.

SAPROPHYTIC MICROCOCCI. 21?

on exclusion of air at the bottom of nutrient agar, the
growth being accompanied by the development of gas
and foul smell.

Micrococci of Putrefaction.

Besides the forms already mentioned there are pro-
bably a number of micrococci which play some part in
the ordinary processes of putrefaction. At the com-
mencement of putrefaction more especially, and also
when it occurs at a moderate temperature, micrococci of
varying size and arrangement are always observed in
enormous numbers in the substrata ; they multiply
actively for some time, and must exert some preparatory
or direct action. Isolation of these organisms, and the
determination of their special action and the part they
play in the process of putrefaction, must be the subject

Fig. 58A.— Micrococci of various sizes Fig. 58s.— Micrococci
from putrefying blood X 700. arranged in tetrads

X 700.

of subsequent investigations. Fig. 58A shows some of
these micrococcus forms from blood which had stood
for 4 days at about 10° C. ; fig. 58B shows micrococci
arranged in fours which had developed in wound secre-
tions in man (both after Koch).

Some saprophytes are of interest to us because they
are frequently found as accidental colonists on the jelly
plates and on other nutritive substances ; they are evi-
dently very widely distributed in our surroundings, and
can enter the cultivations from the air or by contact
with a great variety of substances. Hence the forms
described here represent only a small selection from the
micrococci which have been met with in the Laboratory
at Gottingen. A more complete description will shortly
be published in another place.

218 CLASSIFICATION OF THE MICRO-ORGANISMS.

Micrococcus candicans.

Moderately large micrococci, completely round ; unite
together to form irregular masses. In gelatine plates
the colonies lying in the substance of the jelly present
after two days the appearance of white discs with a
tendency to yellow 0*4 — 0*5 mm. in diameter ; those
which lie on the surface form within the same time pure
milk white flat colonies like drops of varnish, and with
a diameter of 2 mm. or more. Under a low power the
deep colonies are quite circular, with smooth margins,
and of a dark blackish brown colour with indications of
a granular surface ; the superficial colonies present
irregular contours, often indented and sinuous ; the sur-
face is finely granular, and in correspondence with this
shows under a somewhat higher power (100 diameters)
a finely jagged border. In the middle the colonies are
dark brown, but become clearer towards the border,
which is quite transparent. In puncture cultivations
there are confluent white masses and a knob-like eleva-
tion (nail cultivation) on the surface at the entrance of
the canal. — An extremely frequent impurity on plates,
&c.*

Micrococcus cinnabar eus.

Large spherical micrococci often in the form of diplo-
cocci, each half however being completely round ; often
arranged in threes and fours. — Grows extremely slowly ;
after 4 days the colonies lying in the depth are puncti-
form and just recognisable, while those placed super-
ficially have attained a diameter of 0*5 — 1 mm. ; after
about 8 days the latter are elevated above the gelatine
in a knob-like form. The colonies appear at first of a
light wax-red colour, later cinnabar red. Under a low
power the youngest deep colonies are egg or lentil-
shaped, with sharp contour, and of a dark reddish-brown
colour. The superficial colonies are light brown, trans-
parent at the margins, round but with a somewhat
irregular contour, due to projecting heaps of cocci. — In

* Gottinger hygienisches Institut.

SAPEOPHYTIC MICROCOCCI. 219

the puncture cultivation white colonies, which remain
isolated, form in the deeper parts after 4 or 5 days ;
on the surface there is a moderately large knob, at first
rose-coloured, and later of a cinnahar tint. The gela-
tine is not in the least liquefied. The growth is some-
what slower on potatoes. — It occurs frequently as an
impurity on old cultivations.

Micrococcus flavus liquefaciens.*

Comparatively large cocci, arranged for the most part
in twos or threes, or also in masses. They form small
yellow colonies on gelatine plates after two days, around
these a shallow depressed zone can be seen (similar to
the Staphyloc. aureus). The youngest colonies are
(as seen under a low power) circular or oval, or also at
some parts irregular ; their surface is finely granular ;
their contour sharp but finely toothed ; their colour
yellowish brown. The superficial colonies, which are
already causing liquefaction, and are distinctly yellow,
still show the remains of the deep colony in the centre ;
the border forms a ring with a sharp outline which is
here and there interrupted by heaps of cocci, and ulti-
mately several neighbouring colonies coalesce. The
ring is separated from the centre by a broad clear zone,
in which we see isolated, radially arranged lines of
cocci. The whole colony has in this stage a diameter
of 4 — 6 mm., and resembles microscopically the wheel
of a waggon. — In test tubes spherical yellow colonies
appear in two days along the puncture track ; these
become confluent, and soon liquefy the jelly, so that
after 8 days the tube contains an upper zone filled
with clear fluid with the yellow masses of organisms
at the lower part. — It is comparatively common.

Micrococcus flavus tardigradus.^

Large spherical cocci, showing at times peculiar dark
poles ; for the most part arranged in masses. Grows
extremely slowly. After 6 days the deep colonies in

* Gottinger hygienisches Institut. f Ibid.

220 CLASSIFICATION OF THE MICRO-ORGANISMS.

gelatine plates Lave attained the size of 0*4 — O6 mm.,
are of a dark chrome yellow colour, round or oval ; the
superficial ones have a smooth wax-like surface, measure
ultimately J — 1 mm., and project at their middle some-
what above the gelatine. Under a low power the deep
colonies present a sharp, smooth contour, and a uniform
dark olive green colour ; in the superficial ones the
colour becomes lighter and more of a greyish yellow
tinge towards the margin. — In the puncture it is not
till after 6 — 8 days that a row of minute yellow colonies,
which form balls and remain isolated, can be noticed.
The gelatine is not at all liquefied. — Less common than
the forms mentioned before ; often occurs along with
M. cinnabareus.

Micrococcus coronatus.*

Cocci somewhat more than 1 /*. in diameter, single
or arranged in short chains or masses.^-On gelatine
plates the colonies appear on the second day as whitish
yellow points ; those which lie superficially project some-
Avhat above the gelatine, and are surrounded by a sKghtly
depressed zone. The deep colonies appear, when magni-
fied 80 times, as very dark opaque sharply defined plates.
In the superficial ones the remains of the deep colonies
are altered in a peculiar manner ; at two or three places
of the disc, which was formerly circular, short pointed
processes project at equal intervals frorn the periphery ;
the remains of the deep colonies which have become
broadened out in this peculiar manner are of a dark
colour, but are now surrounded by a broad yellowish-
brown border, the superficial extension of the cocci.
On the following day the gelatine is liquefied in the
neighbourhood of this border ; a ring has formed at a
certain distance from the dark centre, and surrounds
the original colony like a crown or halo. At times the
colony lies somewhat excentrically in the ring, which is
then more of an oval form. Between the ring and the

* Gottingcr hygienisches Institut.

SAPBOPHYTIC MICROCOCCI. 221

original colony there is clear fluid. A low power shows
at this stage that the contour of the original colony is
no longer quite sharply denned, the ring having an
irregular margin and granular surface. — In the puncture
cultivation the growth and the liquefaction of the gela-
tine does not present much that is characteristic. — The
organism was several times met with in examinations
of air.

Micrococcus radiatus.

Micrococci under 1 p. in diameter, at times arranged
in short chains, more frequently in small masses. —
Even in 24 hours they form visible colonies ; after two
days they are almost 1 mm. in size. They have a white
appearance with a yellowish green lustre ; under a low
power they are yellowish brown with sharply defined
contours, granular, round, or with somewhat irregular
borders ; at times they form a series of out-growths,
so that they appear like star-fish. In the middle a
small remnant of the deeper part of the colony usually
persists as a dark centre. At this stage the colonies
sink a little into the gelatine, which has become gra-
dually somewhat liquid, and after one or two days more
a very delicate regularly arranged circle of rays has
been formed from the out-growths; from the centre
thickly packed delicate threads project with a radial
arrangement, and these increase somewhat in breadth
towards the periphery, and thus almost run together to
form a ring ; a true sharply defined ring is however not
formed, but the irregular ends of the rays lie more
regularly near one another. After two or three days
more a secondary circle of rays has developed from the
periphery of the first, and eventually a third is formed ;
the radial rays are then however shorter, and the
arrangement more irregular. The whole colony occupies
at this stage a circle 1 to 1*5 cm. in diameter.

This organism also grows in a characteristic manner
in test tubes, and here also the formation of rays be-
comes noticeable. Along the course of the line of ino-
culation isolated centres form from which projections

222 CLASSIFICATION OF THE MICRO-ORGANISMS.

extend in a horizontal direction, so that the line has a
pinniform appearance. At the same time a funnel-
shaped area of liquefaction forms at the upper part, but
this is very pointed and spreads relatively slowly.

Micrococcus flavus desidens.

Yellow Small cocci for the most part arranged as diplococci,

BUCTOOOOCTLB, hut also in triangles and short chains. — After two days
the colonies on nutrient jelly present the appearance of
whitish yellow points, which, under a low power, appear
as oval plates often projecting on one side, yellowish
brown, finely granular ; those which lie superficially have
a lighter zone towards the margin. After four days the
deeply lying colonies have undergone but little alteration,
they have only become more distinct. The superficial
ones are now 5 — 10 mm. in size, but present a round
form with various projections and a dull yellow colour
passing into brown; they form a smooth mucous
layer on the gelatine, and they neither project above it
nor lie markedly below the surface. It is only on
touching it that it becomes evident that the gelatine is
softened and has become pulpy in the neighbourhood of
the colony; after two days more this also becomes evident
by a moderate sinking in of the colony, which is then
surrounded by a very flat depressed ring 2 — 4 mm. in
breadth (hence the name desidens = slowly sinking in).—
In tubes a confluent mass of porcellanous white appear-
ance is formed in the depth of the puncture canal ; on
the surface a yellowish brown slimy deposit, which does
not however reach to the walls of the glass. After eight
days the gelatine below the deposit is so far softened
that a cylinder filled with thick fluid has been formed
3 — 4 mm. in height, and of the diameter of the super-
ficial deposit, to the bottom of which the latter then
gradually sinks down. — Repeatedly observed as an
accidental contamination on plates.

Micrococcus versicolor.
Versicoloured Small cocci arranged in pairs or in masses. They

micrococcus.

SAPROPHYTIC MICKOCOCCI. 223

form white points on gelatine plates after 24 hours;
after two clays, yellow colonies, spherical when lying
deeply, up to 1 mm. in size, circular under a low power,
with sharp contours of yellowish green colour, opaque,
finely granular. The colonies which lie superficially
form flat deposits 2 — 6 mm. in size, increasing even to
10 mm. after four or five days, of irregular form, often
almost quadrilateral, as a rule approaching this form
very closely, and with an irregular outline. The deposit
is gelatinous, glistening at the surface, and yellowish
green, but according to the illumination there is a
greenish arid bluish shimmer like mother of pearl. In
the middle of the deposit there is often a somewhat
projecting knob, the remains of the deeper part of the
colony. Along an inoculation puncture small spherical
colonies of a yellow colour are formed ; on the surface
a deposit with irregular margins as if eaten out and
changing colour like mother of pearl. — Common.

Micrococcus viticulosus.*

Micrococci with a very peculiar mode of growth Micrococcus
observed by Katz in the Hygienic Laboratory at Gottin-
gen. They are somewhat oval, and measure about 1*2 p.
in the largest and 1 /*. in the smallest diameters ; they
always form thick zooglsea masses, but without parti-
cularly marked development of gelatinous material. On
gelatine plates their growth is quite different according as
the colonies develop in the substance of the material or
on the surface. In the first case fine hair-like tendrils
develop from a centre, which soon however becomes
scarcely noticeable, and these- form an extremely fine
and delicate meshwork and extend widely. Under the
microscope we see that these processes do not have
smooth contours, but are markedly bulged out ; they
consist of numerous spherical large or small zooglsea
masses arranged in rows like a string of beads. — If the
threads reach the surface, or if from the first the colonies
lie near the surface, a thin deposit is formed of a muddy
white appearance and gelatinous consistence, and spreads

224 CLASSIFICATION OF THE MICRO-ORGANISMS.

very rapidly. This deposit often spreads along the
threads which run in the deeper part of the gelatine,
or sends here and there fine threads into the deeper
layers of the gelatine. — In the puncture and stroke culti-
vations the same appearance is repeated ; in the deeper
part a delicate network of threads is formed, but this is
soon obscured by the more quickly growing superficial
layer; this network spreads out from the inoculation
track in the form of rays like the plume of a feather. —
This organism has as yet only been met with once, and
then as an accidental impurity.

Pigment- Some rarer cocci which attract attention by the pro-

mfcrococci Auction of colouring material may also be mentioned
here, although they are for the most part as yet insuffi-
ciently known, and do not perhaps all belong to the
micrococci. (M. cinnabareus, flavus, &c., see above ;
Micrococcus prodigiosus, see Bacillus prodigiosus.)

Micrococcus luteus* — Cells about I/*, in diameter, elliptical,
highly refracting. Form yellow drops, 1 — 3 mm. in diameter,
on slices of cooked potato; on fluid substrata they form thick,
yellow, wrinkled skins. The pigment is insoluble in water.

Micrococcus aurantiacus. — Oval bodies, 1 — 5 p.. in diameter,
occurring singly or united in pairs, in fours or in zooglaea
masses. Orange-yellow spots, which finally form an unin-
terrupted layer, especially on boiled white of egg ; a thick,
golden-yellow layer on nutrient solutions. Colouring matter
soluble in water.

Micrococcus chlorinus. — Occurs in the form of a finely
granular zooglsea ; forms yellow or greenish layers on nutrient
solutions and boiled eggs. Colouring matter soluble in
water, decolourised by acids.

Micrococcus cyaneus. — Elliptical spheres, giving to nutrient
solutions and slices of potato an intense blue colour. The
colouring matter is very similar to that of litmus ; it is
soluble in water, becomes red with acids, and again assumes
the blue colour on neutralisation of the acid by ammonia.

Micrococcus violaceus. — Elliptical cells, larger than Mio.
prodigiosus, often united in chains, form violet blue gela
tinous clumps and patches on boiled potatoes.

* All described by Schroter, Cohn's Beitrdge zur Biologic der Pflanzen.
Bd. 1, Heft 2.

SAPROPHYTIC MICROCOCCI. 225

Micrococcus fulvus. — Spherical cells 1'5 ju. in diameter,
frequently united in pairs, with tough intercellular sub-
stance. Form rusty red drops of firm consistence and about
•5 mm. in diameter on horse dung (Cohn, Beitrage, Bd. 1.
Hft. 3).

To the pigment-producing micrococci belong also —

Micrococcus Juzmatoides.

Discovered by Babes as the cause of red sweat (sueur rouge). Micrococcus
Micrococci 1 /j.. in length and 0'6 p. — 0*8 fi. in breadth, united °f red sweat.
by a gelatinous zooglaea mass of a uniform red colour. These
zooglaea masses surround the hairs on those parts of the body
where the red sweat is formed, e.g., the axilla. The cocci
can be stained by Gram's method; they grow on white of
egg at 37° C., and here also produce the red colouring matter,
which has similar reactions to that formed by Bacillus
prodigiosus.

Sarcina lutea.*

Bound cells more than 1 P. in size, which divide in Yellow
three axes ; the daughter cells remain united together, s£
and thus packet-like colonies are formed resembling
corded bales of goods ; these again may be united
together in larger packets. When sown on gelatine

•&

Fig. 59.— Sarcina X 600. Fig. 60.— Sarcina X 650.

Drawn as if lying in one plane. Diagrammatic picture.

plates the colonies form in two days yellow points which
lire just visible, and which under a low power present
the form of irregular plates in part lobate and furnished
with projections grey in colour but transparent towards
the margin. In punctures and strokes on gelatine,
agar, and slices of potato, a slowly growing yellow
confluent mass is formed. It is not uncommonly
obtained from the air as an accidental impurity.

* Hygienic Laboratory at Gottingen.

15

Orange-
coloured
sarcina.

226 CLASSIFICATION OF THE MICRO-ORGANISMS.

Sarcina aurantiaca.

Observed in Koch's laboratory, and frequently employed
in disinfection experiments. (Mitth. a. d. Kais. Gcs.
Ami, vol. 2). On nutrient jelly it forms slowly grow-
ing orange yellow colonies with gradual liquefaction of
the gelatine. A more detailed description is wanting.

Sarcina
ventriculi.

Cultivation
experiments.1

Sarcina ventriculi.

Discovered by Goodsir in 1842. Is found in the
contents of the stomach in man and animals, and
especially in the vomit ; is most frequently observed
in those cases where there are intense fermentative
processes favoured by retention of the contents of
the stomach ; colourless or yellowish brown, round or
slightly oval cells, with an average size of 2'5 /M.,
united in groups of eight forming small cubes rounded
at the angles ; these are bound together to form larger
packets.

Falkenheim has recently obtained cultivations of this
sarcina on gelatine plates ; they formed after 36 to
48 hours roundish, for the most part prominent,
colonies of a yellowish colour. On microscopical ex-
amination colourless spherical cocci 1*5 p. in diameter
were found in these cultivations, as well as numerous
diplococci and tetrads, but no cubical packets. Growth
also occurred on other nutritive media, potatoes, blood
serum, &c., but the arrangement of the cocci charac-
teristic of sarcinse was not present. On the other hand,
this arrangement was well marked in cultivations in
neutralised hay infusion, which showed after 24 hours
brownish flocculi and a scum consisting of small brownish
scales. In the scum as well as in the flocculent deposit
were numerous sarcina packets with a distinctly cubical
arrangement. On the addition to the hay infusion of
2 per cent, of cane or grape sugar growth was very
luxuriant.

If the hay infusion was decolourised with animal
charcoal, and then a solution of litmus added, it became

SAPROPHYTIC MICROCOCCI. 227

evident that an acid reaction was produced by the
vegetation of the sarcinae. Falkenheim was also able Iodine
to confirm the observation made by former writers, that
the outer membrane of the sarcina cells gives a cellulose
reaction with iodine and sulphuric acid, or with a solution
of iodine and chloride of zinc. If a little fluid contain-
ing sarcinae is placed on a slide, and a drop of Schultze's
solution of iodine and chloride of zinc is added to and
mixed with it, and if a cover glass is placed on the
fluid, the outer membrane of the cells is seen after some
time to present a distinctly reddish violet colour. Aniline
dyes, which are as a rule very greedily taken up by the
sarcinae, and must therefore be employed in very dilute
solutions, stain the contents of the cells. Nuclei cannot
be demonstrated in the cells.

For the present it is doubtful whether this Sarcina
ventriculi is identical with the Sarcina lutea described
above, and which is everywhere present. Comparative
cultivations and comparative measurements of the size of
the individual cells are as yet wanting ; the fact that in
Sarcina lutea distinct cubical arrangement of the cells
occurs in gelatine and potato cultivations, points for the
present against any such identity.

There are many statements (varying somewhat with Occurrence of
regard to the size of the cells and the composition of
the packets,) as to the occurrence of sarcinae in other
parts of the human and animal body, in the sputum and
pulmonary tissue, in the urine, in the blood, &c., as
well as outside the body on the most various nutritive
substrata. In the first mentioned cases it is probable
that micrococci arranged in fours, especially micrococcus
tetragenus, have been mistaken for sarcinas. Whether
in the other cases other species of sarcinae than those
described here have been present cannot in the mean-
time be decided. — Zopf has found in the caecum of Zopf's Sarcina
domestic fowls a species called by him Sarcina in- mtestinalis-
testinalis, the colonies of which, however, do not form
cubical packets, but plates composed of tetrads corre-
sponding to the vegetative form merismopedia, but
eventually arranged in several superimposed layers and

228 CLASSIFICATION OF THE MICRO-ORGANISMS.

Sarcina then representing a true sarcina. — The Sarcina lito-

lis, &c. ra-fag Reitenlachii hyalina, formerly reckoned here, has
apparently only a merismopedia-like arrangement of
the cells, and its other characters as well as its relation-
ship to the algae or to the hacteria are as yet doubtful.

In pus, secretions, &c., of the human body, the
following micrococci have also been occasionally observed
as saprophytic parasites ; their characteristics must
however be more fully worked out.

Micrococcus cereus albus.

Cocci 1'16 /n. in diameter, single or in groups, at
times also arranged in short chains. They form white
points on gelatine plates during the first few days ; these
subsequently spread out on the surface and ultimately
attain a size of 1 — 2 mm. In stroke inoculations a white,
dull stearin or waxy-like layer is formed with somewhat
thickened, irregular margins. On blood serum a greyish
white dull line appears along the line of inoculation ;
on potatoes a greyish white layer of medium thickness. —
Found by Passet on pus, but probably without pyogenic
properties, as injections and inoculations of the culti-
vations into animals produced no results.

Micrococcus cereus flavus.

Microscopical characters and growth in cultivations
like the foregoing, only the colour of the colonies soon
passes from the original white to a dark citron yellow. —
Also isolated by Passet from pus ; without pyogenic
action.

Micrococcus citreus conglomerates.

Observed by Bumm in pus from blennorrhoea, and
also in dust from the air. Forms firmly agglomerated
masses which resemble tuberculated knobs ; if these are
crushed and diluted with much water we see diplococci,

SAPROPHYTIC MICROCOCCI. 229

which have the tendency to unite in fours, and which
very much resemble the micrococcus of gonorrhoea.
The average size is 1*5 /*. — Forms citron yellow
colonies on gelatine, which extend over the gelatine like
a tongue, and are raised like a wall at the margins ; the
surface is at first moist and slimy, later cracked and
scaly. — Inoculation on animals produces no effect.

Micrococcus lacteus faviformis.

Frequently found by Bumm and Bockhari in the
vaginal secretion, also in the secretion from the cervix,
in sputum, &c. In these materials it usually forms
isolated diplococci ; preparations from cultivations, on
the other hand, present a peculiar honeycomb appearance
(hence the term faviformis), the individual diplococci
lying side by side with their long diameter in the same
direction. Each diplococcus measures on an average
1'25 p. and consists of two hemispheres which are
separated by a fissure ; the latter is narrower than in
the gonococcus, but otherwise there is a great morpho-
logical similarity between the two cocci. — It grows
readily on the most various soils at the ordinary
temperature, and forms small points in the stroke
inoculation, which gradually develop to milk white con-
fluent colonies. — Not infective.

Micrococcus albicans ampins.

Found at times by Bumm in vaginal secretion. Diplococci,
which are similar in form to the gonococcus, but are dis-
tinctly larger. "Before division the hemispheres may attain
the size of 2'28 /*. Grows on nutrient jelly at the tempera-
ture of the room in the form of greyish-white lines.

Micrococcus roscus.

Obtained accidentally on nutritive substrata from the
dust of the air (Bumm). Diplococci like the gonococcus, but
with a broader division between the hemispheres ; size=l —
1*5 /*. Grows luxuriantly on nutrient jelly at the ordinary

230 CLASSIFICATION OF THE MICRO-ORGANISMS.

temperature without causing liquefaction; forms in stroke
cultivations broad raised stripes, with a moist, shiny, granular
surface, and wall-like raised margins. The colour of the
colonies is a distinct rosy red.

Diplococcus albicans tardissimus.

Cocci which are morphologically completely identical with
the micrococci of gonorrhoea ; the concave form of the division
in the diplococci is also present. They stick together some-
what more readily than the gonococci, and form small masses.
They grow extremely slowly on nutrient jelly, the inoculated
track only attaining the breadth of 1 mm. after some weeks.
On blood serum at the body temperature whitish points
develop after 2 or 3 days, which finally form thin greyish-
white, spots, with jagged contours and slightly moist surface.
— Cultivated on several occasions by Bumm from pus from
the urethra, but quite harmless.

A diplococcus has also been cultivated by E. Frankel* from
vaginal secretion which forms on nutrient agar a delicate
layer consisting of bundles branching off at right angles from
the line of inoculation ; it never grows in the deeper parts.
More detailed statements are as yet wanting.

Miller has isolated a coccus from carious teeth which occurs
singly or in chains, and forms in nutrient jelly luxuriant
spherical colonies, in the neighbourhood of which the gelatine
becomes pulpy ; also another which forms irregular masses,
and very quickly liquefies the gelatine so that a funnel-shaped
depression appears in the tubes 4 — 6 hours after the inocu-
lation, and after 36 hours a broad canal filled with fluid
reaches to the bottom of the glass. See below.

We may also mention —

Ascococcus Billrothii.

The small spherical cells (micrococci) are united to form
peculiar colonies. On the surface of nutrient solutions it
forms a creamy skin in which numerous bodies of spherical
or oval shape can be distinguished even macroscopically.
Under the microscope it is evident that each of the bodies
consists of an extremely resistant envelope 10 — 15 jt. in thick-
ness, jelly-like and cartilaginous ; one or several spherical
* Deutsche med. Woch., 1885, No. 2.

SAPROPHYTIC MICROCOCCI.

231

or elliptical bodies are enclosed in it, 20—70 and more
/*. in diameter, consisting of closely aggregated spherical
bacteria, and an uncommonly firm scanty intercellular sub-
stance (fig. 61).

It was first ob-
served by Billroth
on putrid meat in-
fusion, then by
Cohn on ordinary
nutritive solutions ;
in the latter it gives
rise to a cheesy
smell, converts the
original acid reac-
tion into a markedly
alkaline one, and
leads to the deve-
lopment of consi-
derable quantities of
ammonia. It develops also on slices of turnip, in the
form of a whitish-green slimy mass; in beetroot juice
it sets up a viscous fermentation.

A development of the gelatinous enveloping substance
to the degree as yet reckoned as characteristic of asco-
coccus has been also observed in various cocci and
bacilli (as in Leuconostoc, in Mic. citreus conglom.,
Clostridium polymyxa, and in various other bacteria not
yet isolated pure). It is doubtful whether the produc-
tion of this marked gelatinous mass is constantly present
in the species mentioned ; at all events, on account of
its extensive distribution, it does not appear sufficient of
itself to serve as the distinguishing characteristic of an
individual species or family.

Fig 6L_Ascococcus Billrothii x 65.

Large tuberous cell families surrounded

fc}^ T^61 ones' al! °? them *?eing em~

bedded in masses of micrococci.

232 CLASSIFICATION OF THE MICRO-ORGANISMS.

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234

II. BACILLI.

(For the characters of the genus, see p. 172.)
A. BACILLI PATHOGENIC ix MAX.

Bacillus anthracis.
(Bacteridie du charbon, Milzbrandbacillus.)

Morphological Kods 5 to 20 p. in length, and 1 to 1*25 p.. in breadth,
anthrax which divide when they have grown to about double their

length. Bacilli are frequently found with a commencing
transverse division in the middle; many are bent at
this place, or are loosely connected, the two segments
forming an angle with each other. — The rods present
somewhat different appearances in preparations which
have been made by drying a thin layer of blood,
of the pulp of the spleen, &c., and subsequent
staining. The chains of bacilli are then dis-
tinctly segmented ; the individual bacilli do
not show any difference in length and breadth,
"ri 62 kut are truncated at the ends, not rounded
off; the segments are not divided by a trans-
verse line, but the clear line of division has a small
swelling in its middle, and the point of union between
the two segments presents a slightly knob-like thicken-
ing. Flagella have not been observed ; the rods are
always motionless. — On cultivation on different media
the thickness of the rods may vary somewhat, without
the characteristic form being otherwise altered. Mani-
fold involution forms occur under unfavourable circum-
stances. (See page 157.)

On suitable soil, and at a temperature of about 36°
C., the bacilli form long threads, which may be much
twisted, and often attain 100 times the length of
the original bacilli. After some time small, highly
refracting granules appear at regular intervals in the rod,
and develop into roundish spores, while the threads

BACILLUS ANTHRACIS.

235

become gradually dissolved. The spore has an egg-
shaped form, and is embedded in a spherical transparent
mass. When the spores germinate this mass loses at
first its spherical form, then the swollen external
envelope splits at one pole, and the germinating tube

A M

Fig. 63A.— Anthrax bacilli (after Koch) X 650.

A , from the blood of a guinea-pig.

B, from the spleen of a mouse after being cultivated for three

hours in aqueous humour.

taCjc/ / r.2r-.

/? , V, ^ X

/

Fig. 63s. — Anthrax bacilli ; spore formation and spore germination.
(After Koch.)

A , from the spleen of a mouse after cultivation for twenty-four hours
in aqueous humour. Spores arranged like strings of beads in the
threads X 650.

B, germination of the spores X 650.

C, the same more highly magnified X 1650.

shoots out in the direction of the long axis of the spore ;
the latter at first remains attached to one end of the
young rod.

The anthrax bacilli are easily cultivated on artificial
nutritive substrata, on slices of potato, on gelatine, on

'236

BACILLI PATHOGENIC IN MAN.

Growth on

gelatine

plates.

seeds of plants containing starch, on juicy roots ; they
may also be cultivated and form spores at a suitable
temperature in alkaline urine, in neutralised hay infu-
sion, in meat infusion. They belong to the aerobes, in
so far that they only grow imperfectly when oxygen is
excluded ; attention must also be paid in cultivations to
the great sensitiveness of the anthrax bacilli to an excess
of acid in the nutrient substrata. — In plates of nutrient
jelly they form after 24 to 36 hours small scarcely visible
points; under a low power, however, a characteristic
appearance can be seen at this stage ; the round, dark,
greenish-black colonies have an irregular wavy contour.

Fig. G4. -Anthrax colony in gelatine.
a, after 24 hours. b, after 48 hours X 80.

This wavy margin becomes more and more marked as
the growth of the colony increases, and at once becomes
much more distinct and spreads out more quickly on all
sides when the colony has reached the surface of the gela-
tine. Under a low power the dark remnant of the deeply
placed colony can only be seen in the middle ; around
this centre, however, there is a light-brown or light-grey
shiny mass, which consists of numerous wavy, curly
bundles, recalling the appearance of the locks of hair on

BACILLUS ANTHRACIS. 237

the head of a medusa. Ultimately individual threads,
or bundles of threads, hranch off from the irregular
periphery, and grow over the gelatine in various direc-
tions. At the same time the gelatine is liquefied over
a small area ; the colonies, which have now a diameter
of 2 to 4 mm., hegin to float and break down at their
margins under the action of the fluid formed. — In punc- Puncture
ture cultivations in gelatine a delicate whitish line is Cl
formed along the needle track, from which fine threads
run off at right angles, and grow in a ray-like form into
the jelly, extending furthest on and near the surface, to
a less extent at the deeper parts of the puncture ; here
also slow liquefaction begins after two or three days, in
such a way that the radiating branches at first remain,
and it is only in the course of eight days that the
colonies sink to the bottom of the liquefied area, which is
now more extensive. — On the addition of a small quantity
of agar to the nutrient jelly, no liquefaction occurs. On Growth on
slices of boiled potatoes the anthrax bacilli form greyish- J
white elevated gelatinous deposits with a rough surface;
these deposits do not extend over the whole surface of
the potatoes, but only spread for 3 to 5 mm. from the
line of inoculation. On blood serum they form whitish
layers ; in meat infusion they cause a cloudy turbidity,
which develops by preference at the bottom of the
vessel.

When introduced even in minimal quantities into the Action on
blood of living animals or man by intravenous injection JJ^Jflals and
or subcutaneously, the bacilli cause anthrax, which either
takes the form of local symptoms, anthrax carbuncles,
and then not uncommonly ends in recovery, or appears
as a septicaamia, and then usually rapidly ends in death.
Anthrax was the first case in which an infective disease
occurring in man was proved with certainty to be due to
a vegetable micro-parasite, the organism being at the
same time inoculable on various animals, and being thus
suitable for experimental study. The smallest trace of
a cultivation of anthrax bacilli inoculated on mice,
rabbits, guinea-pigs, hedgehogs, sparrows, sheep, and
horses, causes the illness or death of the animals from

238

BACILLI PATHOGENIC IN MAN.

anthrax, death occurring in the case of mice after
about 20 hours, and in that of rabbits after 42 hours.
After death the bacilli are found in largest numbers in
the swollen spleen, and also in all the capillaries,
especially in the lungs, liver, kidneys, and intestine ; in
the larger vessels, on the other hand, often only single
bacilli are met with. — Certain races of sheep (Algerian),
white rats, dogs (especially adults), and frogs, are
entirely, or to a certain degree, immune against anthrax.

:;SP W ||'f.;WWS \

L'/lHiff I /

Fig. 65. — Anthrax, section from the liver X 700.

Cattle are comparatively slightly susceptible to anthrax
after inoculation, but on the other hand readily succumb
to the natural infection, which generally spreads in the
case of sheep and cattle from the intestine as the result
of infection by the food. Non-spore-bearing bacilli do
not appear to be able to retain their vitality in the intes-
tine ; on the other hand, it has been shown with regard
to spores that they can sprout in the intestine of sheep,

BACILLUS ANTHRACIS. 239

and penetrate through the uninjured mucous mem-
brane.

In the body of living animals the bacilli multiply only Conditions of

,„. J, 5> r™ • j j 8P°re t'orma-

by fission, and never form spores. These arise on dead tion.
nutritive substrata, but only under definite conditions,
among which a suitable temperature is the most impor-
tant. The highest limit of temperature is about 43°
C. ; the lowest from 12° to 18° C. ; below 12° C. neither
growth of threads nor spore formation seem to occur.
Hence if the bodies of animals which have died of
anthrax are buried very deeply in the soil, where in our
climate there is a constant temperature below 12° C.,
spore formation does not occur, and the bacilli them-
selves speedily die without having passed into a resting
form. Pasteur's assertion that the bacilli or their spores
are preserved in the buried bodies, and that they are
then brought up to the surface of the soil by means of
worms, is thus wholly improbable. On the contrary, we
have to explain the occurrence of an epidemic of anthrax,
according to Koch, in the following manner : the germs Mode of
which are distributed since ancient times in marshy anthrax*
regions, on banks of rivers, &c., can again develop on bacilli-
suitable vegetable substrata, and there form new spores ;
these are carried to pasture lands by floods, and
thus become mixed with the fodder. — This mode of
spread also explains the infection from the intestine,
which is much the most frequent mode observed.
Recently Schrakamp and Friedrich have mentioned the
possibility that the growth and development of the
anthrax bacilli may also occur in the upper layers of the
soil ; while Kitt regards cattle dung as the chief nutritive
substratum in which the development and spore formation
of the bacilli occurs in the regions infected by this dis-
ease. (See the chapter on the exciting agents of disease.)

Of great scientific value is the discovery by Toussaint Artificial
and Pasteur that the anthrax bacilli can lose their patho-
genie properties by the moderate action of abnormally bacilli-
high temperatures, or of small doses of poisonous sub-
stances, while their morphological and biological cha-
racters remain otherwise unaltered. On the mode in

240 BACILLI PATHOGENIC IN MAN.

which the means used for the attenuation are employed
depends apparently the answer to the question whether
and within what time the hacilli can regain their viru-
lence on subsequent continued cultivation under favour-
able normal conditions. The degree of attenuation can
he modified with precision to any desired extent by the
method described by Koch. — The inoculation of suffi-
ciently attenuated bacilli sets up in the case of sheep,
cattle, &c., a mild disease ending in recovery, after which
the animals in question are immune for a considerable
time against the virulent anthrax bacilli (Pasteur's
protective vaccination) .

Buchner's According to Buchner the anthrax bacilli are extremely

experiments, variable in morphological and biological characters, and by
variations in the cultivations can be transformed, after pass-
ing through a series of intermediate stages, into the closely
allied hay bacilli (Bacillus subtilis), and in like manner the
latter can be converted by suitable cultivations into true-
anthrax bacilli. Buchner in the first place cultivated the
anthrax bacilli for many generations in a nutritive solution
containing extract of meat, peptone and sugar ; after a short-
time these cultivations were only virulent in large doses, but
the bacilli again regained their full virulence in the animal
body ; ultimately they entirely lost their pathogenic pro-
perties, but grew and behaved exactly like hay bacilli. Koch
has shown in the most convincing manner that this supposed
transformation can only have been due to contamination and
the gradual displacement of the anthrax bacilli by the hay
bacilli. Had it been a case of gradual loss of pathogenic-
properties, there must have been, in the first place, just as in
the case of the anthrax bacilli cultivated at high tempera-
tures, a less severe and no longer fatal disease ; in Buchner's
experiments there was no effect after small doses, while after
large doses there was the complete fatal action ; this circum-
stance, as well as the increase of virulence after passage
through the animal experimented on, corresponds entirely
with the behaviour of impure nutritive substrata containing
only a few infective organisms from which by the culti-
vation in the body the pathogenic organism is again isolated
.and cultivated pure. — Buchner tried to carry out the trans-
formation of the hay bacilli into anthrax bacilli by cultivating
the former in the first place in white of egg with a little meat
infusion, and then in fresh rabbit's blood which was con-
stantly shaken up with air but not sterilised. From such
blood cultivations further cultures were made in meat in-

BACILLUS ANTHRACIS. 241

fusion, and by the injection of large quantities of the spores
formed in this medium a fatal disease was obtained in some
cases which Buchner looked on as anthrax. Since it has,
however, been demonstrated that among the so-called hay
bacilli various pathogenic organisms are present which
resemble the anthrax bacilli and give rise to similar diseases
(see page 242), and that in meat infusion and putrefying blood
spores of these pathogenic bacilli often occur, Buchner's
experiments cannot be regarded as convincing; the disease
which was finally obtained was possibly not anthrax, but
malignant oedema or some other affection. This possibility
becomes a probability when we consider how extraordinarily
constant anthrax bacilli and hay bacilli have proved to be
under the most varied conditions of cultivation in the
hands of those investigators who rightly estimate the magni-
tude of the sources of error in cultivations in fluid substrata.
— Further, Buchner states that he has been able to obtain a
transformation of anthrax bacilli in the first place into an
intermediate form, and then into true hay bacilli within a
very short time (24 hours) by cultivating them at 36° C. in
nutrient solutions composed of meat infusion, yolk of egg
(from old eggs preserved in lime water), and a little alkali.
The yolk of egg was not sterilised, and the inoculation was
made from the spleen of an animal which had died of
anthrax ; thus there were two possible modes of entrance of
extraneous germs, and that such an unintentional contamina-
tion had in all probability taken place is likely from the
totally different results obtained in numerous other cultiva-
tion experiments with anthrax. — Recently Prazmowski has
in so far supported Buchner's views that he has also in
cultivations made by Buchner's method obtained a scum-
forming non-pathogenic motile bacillus which he looks on as
the result of the transformation of the anthrax bacilli. On
the other hand he ascertained that this organism was not
identical with Bacillus subtilis, which is totally different from
the anthrax bacillus in the mode of the sprouting of its
spores, and in its other constant characters. Experiments
which the author has set a-going with regard to Buchner's
views have only led to the conviction that the development of
extraneous organisms is a very frequent and scarcely avoid-
able occurrence in the method of experimentation described,
and that there was in no case any guarantee that the bacilli
ultimately obtained had been developed from the anthrax
bacilli inoculated. — Kurth comes to a similar conclusion as
the result of his own experiments in his work on "Bact.
Zopfii."

A great variability in morphological form has also been
wrongly attributed to the anthrax bacilli by various observers.

16

242

BACILLI PATHOGENIC IN MAN.

Thus more especially Buchner, Zopf, Fokker, Archangelski,
and Roloff have observed cocci as a vegetative form of the
anthrax bacillus both in cultivations and in diseased animals.
Numerous careful examinations by those observers who are
thoroughly acquainted with microscopical technique, and
who know how to avoid the sources of error mentioned above
(page 182), have demonstrated the inaccuracy of this assertion,
— De Bary states that he has observed in certain cultivations
(peptone solutions) a breaking up of the threads of the
anthrax bacilli into round bodies which become aggregated
in the form of grape-like or irregular groups, but which with
doubtful exceptions proved to be dead. It is evident that
these degenerative forms, which are very various, have not
the slightest claim to be designated as cocci.

therede
bacillus.

Bacillus osdematis maligni.

Discovered by Koch as the exciting agent of malignant
oedema, a fatal disease of mice, guinea-pigs, and rabbits ;
formerly termed by Pasteur vibrion septique. Malignant
oedema has recently also been observed in domestic
animals and in man.

Morphological The oedema bacilli, which are morphologically similar
to ^ne anthrax bacilli, are rods 8 — 3' 5 p. in length and
i — I'l pt jn breadth ; usually two or three bacilli remain

united together, and then
the thread is two or three
times longer; indeed one
may frequently find long
pseudo-threads 15 to 40
/*. in length. The threads
scem to be comparatively

r

stiff, and are often broken or

bent ; at times also they are
ITT.

looped and twisted around

each other En stained preparations they frequently
present a somewhat granular appearance, owing to
irregular deposit of the colouring matter. Anthrax
bacilli differ from the oedema bacilli by their somewhat
greater breadth, their truncated ends, and their peculiar
segmentation in stained preparations. Further, one
does not find in fresh anthracic blood the numerous

Fig. 66.-Baciiiu8 of malignant

oadema (vibrion septique), after

Koch, x 700.

A, from the spleen of a guinea-pig,

B, from the lung of a mouse.

BACILLUS (EDEMATI6 MALIGNI. 243

long threads of the oedema bacilli, and the oedema bacilli
are sometimes, though not always, motile, while the
anthrax bacilli are always motionless. The most marked
morphological difference between the two is, however, the
mode of spore formation. In the oedema bacilli this does not
occur in the threads in the same way as in
the anthrax bacilli, but the individual bacilli $ $ ff ^
show before the spore formation a slight j /> ^j /
swelling in the middle or at one end, so f g

that a spindle or tadpok form results,

, . , . , , , Fig. 67.— Spore

and in this swollen part the large oval formation in the
spore, at first dull, but later highly re- ^f^eSfx
fracting, is formed, and when its forma- 700.
lion is complete the colourable remains of the bacilli
gradually disappear.

There is considerable difficulty in cultivating the Cultivation of
oedema bacilli, because they are marked anaerobes, so bacilli.61
much so that they only form visible colonies when
oxygen is pretty completely excluded. They do not
grow at all on gelatine plates, even in the deeper layers ;
nor do they grow along the inoculation track on gelatine,
agar, or blood serum. On the other hand they can
grow when they are inoculated at a certain depth in
tubes containing nutrient agar or blood serum, in such
a manner that the canal of inoculation becomes tightly
closed over the material introduced. As Hesse first
observed, a diffuse muddiness of the nutritive material
consisting of bacilli appears in the nutrient agar, with
here and there more markedly muddy lines or clouds. At
the, same time gas bubbles are formed within the inocu-
lation canal, which penetrate into the agar in various
directions, often divide it transversely, and drive up the
separated portion as high as the cotton wool plug, and
at the same time so compress the agar that a muddy
fluid is separated which collects at the bottom of the
glass, and contains numerous bacilli. The escaping gas
has a slight, somewhat heavy smell. — Blood serum is
quickly liquefied by the bacilli, and there is at the
same time marked development of gas ; in a few days,
when kept in an incubator at 37° C., the whole mass

244

BACILLI PATHOGENIC IN MAN.

of the blood serum is converted into a yellow fluid,
at the bottom of which there still lie some pieces
of the serum with eaten away, shreddy margins. — In
nutrient gelatine a spherical layer, 5 — 10 mm. in
diameter, forms at the bottom of the inoculation punc-
ture, around the material inoculated, the periphery of
which shows fine radiating markings, and the contents
consist of liquefied and somewhat turbid jelly. The
oedema bacilli grow best in a nutrient jelly which con-
tains 1 — 2 per cent, of grape sugar ; and very charac-
teristic cultivations are obtained in test tubes if the
gelatine is fluid when inoculated, and the material well
distributed through the whole jelly by shaking it before
it is allowed to solidify. After two or three days a
number of small spheres, J — 1 mm. in diameter, and
filled with fluid, form in the lower part of the tube, and
these show under a low power the radiating marking of
the periphery. The colonies extend from the bottom of
the vessel to about 2j cm. below the surface. The
upper 2J cm. of the gelatine remain completely unal-
tered. By pouring on oil,
introduction of carbonic
acid, &c., one can arti-
ficially raise the upper
limit within which visible
colonies are formed.*

The best temperature
for growth is about that
of the human body ; but
luxuriant growth also oc-
curs at 18°— 20° C., es-
pecially in jelly contain-
ing sugar. Spore forma-
tion has also been observed

Fig. 68. — Cultivations of the bacilli , , -. • , •,

of malignant oadcma in gelatine, at this temperature, but

it occurs more readily and

plentifully at the higher temperature. In the animal
body only bacilli and threads are found immediately after

* After observations by Dr. Liborius in the Hygienic Institute at
Gottingen.

BACILLUS (EDEMATIS MALIGNI. 245

death, but no spores; the latter are, however, observed
when the body has lain for some time after death at a
high temperature.

? The oedema bacilli are apparently extremely widely
distributed in our surroundings. They appear to be phyticife of
present in almost all decomposing substances in greater bacimdema
or less numbers, and they perhaps also take a definite
though limited part in the putrefactive process. As is
shown by the behaviour of the pure cultivations, the
oedema bacilli have the power of energetically peptonis-
ing albumen, and possibly also of further breaking up
the albuminous molecule. A more accurate analysis
of the nature of the decomposition is as yet wanting, at
all events the oedema bacilli can pass through their
characteristic cycle of development as saprophytes. In
accordance with this we find them in the most various
putrid substances, in the bodies of nnimals which have died
of suffocation and have then been kept at a high tempera-
ture, in the faeces, and in the intestinal contents ; their
spores are present in every specimen of earth which has
. been impregnated with putrid fluids, &c. ; they are also
found in the dust of rooms, in the dust of rags, of hay,
&c.

At the same time, also, the oedema bacilli possess Pathogenic
pathogenic properties, and by means of these their pre- fhe^edenaa°
sence can be most easily demonstrated, and they can be bacilli-
most readily isolated from the mixture of other sapro-
phytes. If not too small an amount of garden earth or
hay dust is introduced under the skin of a guinea-pig
(this is best done by making a small cut with scissors
through a fold of skin over the abdomen, and then
loosening the subcutaneous cellular tissue with the
handle of the scalpel so that a small pocket is formed,
which is then filled with earth and the wound closed
with one or two stitches), the animal becomes ill very
soon, and dies in 24 to 48 hours. On post-mortem
examination the most striking appearance is an extensive
subcutaneous oedema extending from the seat of inocu-
tion,the oedematous fluid being clear and red, and contain-
ing numerous bacilli and a few gas bubbles. The internal

246 BACILLI PATHOGENIC IN MAN.

organs are but little altered, the spleen is for the most
part enlarged and of a dark colour, and the lungs have
a pale greyish-red appearance. Immediately after death
few or no bacilli are found in the blood of the heart ; on
the other hand they are plentiful in the juice from the
various organs, and also more especially in and on the
serous coats of the organs. (In this point also this
organism differs in an important manner from anthrax.)
If some time has elapsed since the death of the animal
the bacilli are found everywhere, eyen in the blood of
the heart, in large numbers ; thus they are apparently
able to multiply actively in the dead body. In mice,
however, the bacilli are not uncommonly found imme-
diately after death in the blood of the heart and in the
blood vessels of the organs ; here therefore it is easily
possible to mistake the disease for anthrax. As a
rule, in mice the bacilli are only seen in the crushed
spleen, on the pleural covering of the lungs, and most
beautifully in preparations of the mesentery, obtained
by spreading out a loop of intestine over a cover glass,
loosening the mesentery at the margin of the cover glass,
and subsequently treating it like the ordinary cover glass
preparations (drying, heating, staining). In mice the
osdema is for the most part not very marked ; the aninicils
die very quickly — on an average 16 — 20 hours after
inoculation. — Horses, sheep, and swine are liable to
malignant oedema; on the contrary, according to the
researches of Arloing and Chauveau, cattle are not
affected. — The animals cannot be infected with such
small quantities of bacilli as in the case of anthrax ; to
transmit the disease from one animal to another it is
best to employ small pieces of spleen, or one or two drops
of oedematous fluid, or a portion of the subcutaneous
tissue ; from cultivations it is best to impregnate a silk
thread with a little of the fluid containing bacilli, and
then place this under the skin. The wound also must not
be too trivial, it must really penetrate through the cutis ;
it is only then that the conditions necessary for the
existence of this anaerobic organism are obtained.
Scarcely noticeable symptoms follow the intravenous

BACILLUS (EDEMATIS MALIONI. 247

injection of relatively large doses, 1, 5, 10 drops.— In How to obtai
order to obtain cultivations from the dead body of an f^m the
animal the skin is washed as soon as possible after animal body»
death with sublimate solution, and then with sterilised
water, or the hair is completely singed off at the part ;
then small portions of spleen, diaphragm, or of the
cedematous dorsal muscles, are taken with heated instru-
ments, and introduced into tubes of jelly containing
sugar, and kept at the temperature of 30° C. ; these are
then allowed to solidify.

Kecently several cases of malignant oadema have Malignant
been observed in man. This disease has commonly man.
been designated by surgeons as progressive gangrenous
emphysema (gangrene gazeuse) ; it seems to have been
comparatively frequent before the introduction of anti-
septic methods ; it is now chiefly observed after compound
fractures or deep wounds, into which earth or other
material containing osdema bacilli has passed. A cre-
pitating emphysema of the skin spreads in these cases
from the wound, accompanied with the development of a
very putrid smell ; the muscles are at the same time
converted into a peculiar reddish-brown, loose, frothy
mass, full of gas bubbles ; and death generally occurs in
a few days with comatose appearances and gradual spread
of the oedema. Lately the identity of this gangrene
with malignant oedema has been repeatedly ascertained
by inoculation of animals and by cultivations (Chauveau,
Aiioing,* Brieger, and Ehrlich).

Chauveau and Arloing have observed that animals which Experiments
recover from the disease are immune; injection into the on immunity,
veins produces a similar immunity, which, however, cannot
withstand repeated inoculations. Subcutaneous inoculations
of small quantities produce, according to Loeffler's experiments,
no noticeable disease, but also no immunity (Mitth. a. d. Kais.
Ges. Ami., Bd. I.).

* Bull, de YAcad. de Med., May, 1884, and August, 1884.

248

BACILLI PATHOGENIC IN MAN.

Bacillus typhi abdominalis.

Eberth, Klebs, and Koch were able to demonstrate
in the spleen, lymphatic glands, and Peyer's patches of
patients suffering from typhoid fever, peculiar short,
plump bacilli which were not met with in other diseases.
According to Klebs, long threads develop from these
bacilli, and in these rows of spores are formed ; this
statement was not confirmed by the other two authors,
and probably rests on error owing to the accidental
presence of putrefactive organisms. Meyer and Gaffky
have subsequently confirmed Eberth and Koch's results.
Occurrence of Gaffky found the characteristic bacilli 26 times in 28
bacilli cases of typhoid fever investigated ; and recently similar

Fig. 69.— Typhoid bacilli ; section from spleen X 800.

observations have been made by a number of investiga-
tors. This constant occurrence of the bacilli, which
are limited, as can be shown, only to typhoid affections,
renders it highly probable that they are causally con-
nected with the disease.

The bacilli are present in the diseased parts of the
intestine, in the mesenteric glands, in the spleen and

BACILLUS TYPHI ABDOMINALIS. 249

liver, but not so numerous in the kidneys. They
are not diffusely distributed in these organs, but
always occur in the form of small isolated deposits.
This renders the microscopical investigation especially
difficult ; it is often only after the examination of a large
number of sections that one or a few of these deposits
are found. The masses occur in the form of groups with
irregular outlines lying usually in the capillaries or
smallest blood vessels, these groups being resolved at
their margins into individual bacilli (see fig. 69).

The latter appear as rods 2—3 P. in length, and Morphological
about three times less in breadth. Their ends are
distinctly rounded off. In many cases undoubted spores
are found in the bacilli, presenting the appearance of
round unstained portions occupying the whole breadth
of the rod. — Aniline dyes are slowly taken up, but quite
sufficiently when the staining process is continued for
a considerable time ; the best stains are gentian violet,
Bismark brown, and especially alkaline methylene blue.
With Gram's method the typhoid bacilli are very readily
and completely decolourised.

Gaffky was the first to cultivate these bacilli on suit-
able soil from the organs of patients who had died from
typhoid fever. Former attempts by other investigators
did not lead to a pure culture of the typhoid bacilli.
Gaffky succeeded in 13 cases in obtaining pure cultiva-
tions of the bacilli, by planting on nutrient jelly minute
portions of tissue taken with all precautions from the
interior of the spleen. These cultivation experiments
showed that even in the cases where on microscopical
examination it was only with difficulty and in a small
proportion of the sections that bacilli could be demon-
strated, every minutest portion of the juice of the
organ gave rise to several colonies of bacilli, so that
it was evident that the best idea of the number of
bacilli present, and of their distribution, could be
obtained by the cultivation method. — Cultivations of the
typhoid bacilli have since been repeatedly made ; they
are invariably successful from the organs of fresh typhoid
bodies. Pfeiffer has recently succeeded in isolating

250

BACILLI PATHOGENIC IN MAN.

Characters of
the cultiva-
tions of
typhoid
bacilli.

Growth on
potatoes.

the characteristic bacilli by means of plate cultivations
from typhoid stools, and from the intestinal contents of
typhoid bodies.

When sown on gelatine plates the colonies of the
typhoid bacilli form, after about 86 hours, minute white
points ; when magnified 80 times these appear as irre-
gular, oval, and even whetstone or citron-shaped plates
of a light yellow or yellowish-green colour, with sharp,
smooth borders, and an indistinct granular character.
In the course of 86 to 48 hours more the colonies have
spread out to form a roundish greyish-white flat deposit
1 to 1J mm. in diameter ; these do not form any knob-
like elevation, and project very slightly above the gelatine.
The contour of this layer is irregular, indented, and at
times distinctly branched ; under a low power the
colony, with the exception of the central part, is colour-
less, and shows on the surface numerous lines and
furrows. Liquefaction of the gelatine does not occur at
any stage. — On agar plates at a higher temperature the
characters are similar ; after about 20 hours the young
colonies have the appearance under a low power of pear-
or citron-shaped brownish plates with sharp borders.

In puncture cultivations in gelatine a thin whitish
thread forms along the line of puncture ; at the surface
a greyish-white flat layer is constantly formed, at first
small, but later reaching almost to the margin of the
glass; the outline of the growth shows in the later
stages numerous projections and irregularities. — In
stroke cultivations a similar greyish-white layer forms
on the surface of the gelatine.

The typhoid bacilli can also grow on blood serum,
fluid and solid, in meat infusion, and on other nutrient
substrata. In milk the bacilli grow actively but with-
out causing any noticeable alteration of the milk. —
Their growth on boiled potatoes is extremely charac-
teristic, and of special importance for the distinc-
tion of the typhoid bacilli from all other forms of
bacteria as yet known. Slices of potato inoculated with
small quantities of typhoid bacilli appear almost com-
pletely unaltered after two or three days ; at the most

BACILLUS TYPHI ABDOMINALIS. 251

»

the surface in the neighbourhood of the track of in-
oculation has acquired a somewhat moist, more shiny
appearance. If this part of the potato is touched with
a platinum wire it gives the impression as if the surface
was covered with a resistant skin ; and if we examine
microscopically a minute portion from the surface we can
easily see that this skin consists of masses of bacilli
which have taken possession of the soil over a great
extent, often over the whole surface. If the inocu-
lated potato is kept at 85° C. the development of the
layer of bacilli occurs more rapidly, while otherwise
the appearance of the potato remains the same.

In all these cultivations the bacilli appear under the Morphological
microscope as short, thin rods similar to those observed thTcuitl™ted
in the tissue. Nevertheless long pseudo-threads are bacilli.
almost always formed in the cultivations, and there are
also marked differences in length corresponding to the
various stages of growth. It is also possible to stain
culture preparations with aniline dyes, but it is more
difficult than the stainiDg of other bacilli (e.g., Bacillus
anthracis). — Further, the bacilli taken from the culti-
vations show distinct and often fairly active move-
ments. Spore formation can not be
observed in cultivations kept at 15° —
18° C. ; at 20° C. a few spores are
formed, and between 80° and 42° C.
the spore formation is plentiful. The
spores are situated at the end of the cultivation x
rods, and only one spore is formed showing on the

in each rod in the form of a highly

refracting round body, occupying the and free spores.
whole breadth of the bacillus. Where two bacilli are
joined together it is always the two ends not in contact
which bear the spores.

Inoculation experiments on animals have as yet been Experiments
without result, whether the material used was typhoid on ammals-
stools or the pure cultivated bacilli. Those few experi-
ments in which a typhoid disease was said to follow
inoculation or feeding have evidently been made with
impure material containing other active bacteria. It is

252 BACILLI PATHOGENIC IN MAN.

known that a group of fairly widespread organisms,
which, however, differ totally from the typhoid bacilli,
have this property in common, that when introduced
either hy intravenous or subcutaneous injection, they
kill animals with the symptoms of a gastro-enteritis,
often with marked swelling and ulceration of Peyer's
patches. It is probably to these organisms that we
must ascribe the apparent positive results which certain
authors think they have obtained by inoculation of the
typhoid bacilli ; this remark applies more especially to
the typhoid cultivations isolated by Tayon, and tested
with apparent success on animals and man, for these in
no respect correspond to the characters of pure cultiva-
tions of the characteristic bacilli which constantly occur
in typhoid fever. — Recently numerous experiments have
been made by Gaffky (and also in the laboratory at
Gottingen) with the view of setting up a corresponding
disease in animals with pure cultivations of the typhoid
bacilli. Besides rabbits, guinea-pigs, and rats, calves
and monkeys have also been employed in these experi-
ments ; infection has been attempted by continued feed-
ing, in some cases along with simultaneous employment
qf various medicinal substances, by subcutaneous and
intravenous injections, and by inhalations, but as yet
without any positive result. However, there is always
the possibility that some preliminary preparation of the
animals may render them susceptible to an infection.
The success of such experiments would be of great
importance in completing the proof that the bacilli
described are really the causal exciting agents of typhoid
fever, although the constancy of their occurrence and
their exclusive presence in this disease leaves scarcely
any real doubt as to their significance.
Occurrence of Typhoid bacilli have never as yet been demonstrated
with certainty outside the human body with the excep-
. tion of pfeiffer»s demonstration of their presence in
the dejecta of typhoid patients. It is true that there
are statements by Brautlecht and Klebs as to the suc-
cessful demonstration of typhoid bacilli in suspected
drinking water ; but according to the description which

BACILLUS TYPHI ABDOMINALIS. 253

these authors give of the bacilli found by them it is
certain that neither of them were dealing with typhoid
bacilli. Brautlecht's bacilli were very thin, slender
bacilli ; those isolated by Klebs from the water supply of
Ziirich were not decolourised by Gram's method, they
showed another mode of spore formation, were infective
for rabbits, and were therefore certainly not identical
with the bacilli of Eberth and Gaffky.*

The most distinctive character of the typhoid bacilli
is their peculiar mode of growth on potatoes ; and when
we have to diagnose these organisms the potato cultiva-
tions must be employed as the distinctive criterion.
With the help of this aid to diagnosis it will now per- Modes of
haps be possible to follow more closely the distribution
of the typhoid bacilli in our surroundings and the modes bacilli-
in which it causes infection. What has as yet been
done in this direction rests only on deductions and on
practical experience and statistical facts which are in
many respects open to question, and are in part contra-
dictory. The following views may be deduced from the
knowledge which we have gained during recent years as
to the specific exciting agents of typhoid fever.

We may perhaps conjecture that the seat of entrance
of the infective agents is by preference the digestive
tract ; in favour of this we have the observations as to
the distribution of the typhoid bacilli in the body of the
patient as well as the analogy with many other diseases
which are chiefly localised in the intestine (swine ery-
sipelas, cholera). Nevertheless, in spite of these obser-
vations and analogies, the possibility of some other seat
of invasion is not excluded (see the chapter on the causa-
tion of disease). — Further, from the mode of spread of
typhoid epidemics we may probably draw the conclusion
that a certain preparation of the intestine for infection

* Kleb's article, "Bacillen," in Eulenburg's Realencyclopcedia. —
Lfc'ure on the drinking water supply of (he town of Zurich and its suburbs.
Auasersihl, 1885. — Compare the refutation by Cramer in Die Wasser-
venorguny von Zurich, Zurich, 1885 ; and Die Wasserversorgung von
Zurich und Ausgemeinder ; Entgegnung der erweiterten Wasser-com-
mission auf die Angriffe von He,rrn Prof. Klebs. Zurich, 1885.

254 BACILLI PATHOGENIC IN MAN.

must always take place, that a condition of irritation, a
hyperaemia and detachment of epithelium, such as occurs,
for example, in animals after the injection of putrid
mixtures, prepares a spot for the entrance of the true
infective agents.

If the view as to the important role played hy the
intestine in the production of infection is correct, it be-
comes probable that the transport of the typhoid bacilli
to the seat of infection occurs most frequently through
the food ; and very various articles of food are not less
suitable as vehicles than the drinking water which is
commonly blamed in a somewhat one-sided manner.
Transport by Articles of food and drinking water can evidently be

articles of . . , .., , .... » , , . -, , .„.

food. impregnated with large quantities of typhoid bacilli or

spores in the most various ways; of great importance
for the continued existence and development of the
typhoid bacilli outside the body is, on the one hand, the
fact that many typhoid bacilli leave the body of the
patient in the form of resistent spores, and on the other
hand that their development can occur on the most
various nutrient materials at the ordinary temperature,
and that without any alteration of the nutrient material
noticeable to the naked eye. Thus the channels for the
spread of the infective material from the dejecta of
typhoid patients to articles of food are extremely nu-
merous, and are in a marked manner subject to chance,
which at one time follows no apparent rule, at another
time may present a deceptive appearance of law. It is
necessary to refer in illustration of this to the fact that
the dejecta containing spores are ultimately deposited on
garden earth, on fields, or on meadows, that the un-
altered spores may be thence transported to the dwellings
by fruit, man, &c., and by unforeseen actions and
accidents reach a suitable nutrient medium where they
can multiply plentifully, and from whence further
infection may eventually occur.

It is necessary to bear in mind these numerous and
complex ways in which an infection may possibly occur
in order to some extent to meet the prevailing tendency
to treat these etiological questions in a schematic manner.

BACILLUS PNEUMONLE. 255

In numerous typhoid epidemics a local and seasonal
pre-disposition can be recognised, and Pettenkofer has, as
is well-known, observed that the moisture of the soil plays
an important part in this pre-disposition. How far this
view can be brought into harmony with the biological
characters of the typhoid bacilli will be discussed more in
detail in the chapter on the causation of disease.

Bacillus pneumonia (Friedlander).

The infectious, and at times epidemic character of
certain forms of pneumonia has been repeatedly pointed
out by various observers, — for example by Kiihn,
Jurgensen, and others, — this character leading to the
belief that micro-organisms may be the exciting agents
of the disease. In 1883, Friedlander and Frobenius, as
a matter of fact, found and isolated by cultivation bacteria
in a large number of cases of pneumonia, the organisms
presenting infective properties.

The bacteria were at first only found on post-mortem Occurrence of
examination, especially in the alveolar exudation, mlSH^S"01"*
cover glass preparations of the juice, and in sections;
they were also present in the pleuritic and pericardial
exudation. The same bacteria have also been found by
Ribberfc, Ziehl, and others in the rust-coloured sputum,
and by Friedliindcr, in one of six cases examined, in the
blood obtained by cupping.

These micro-organisms present, under the microscope, Morphological
the form of oval cells ; it is difficult to say whether these characters-
are to be regarded as oval micrococci, or as very short
rods with rounded ends. Friedlander has described
them as micrococci, but in every preparation a relatively
large proportion of the individuals shows such a pre-
ponderance of the longitudinal diameter that they
cannot be reckoned among the cocci ; further, iso-
diametric cells never occur, or only in so far as they are
seen in preparations, where the cells stand at right angles
to their long diameter ; and as also under high powers
of the microscope, even the shorter forms show dis-
tinctly parallel and longitudinal limiting lines, it seems
more correct to designate the organisms as bacilli.

256 BACILLI PATHOGENIC IN MAN.

In this species we not uncommonly find that the youthful
stages only appear as oval, egg-shaped cells, and that
under certain conditions, where the multiplication is very

rapid, these young cells prepon-
derate; but the simultaneous
presence of older individuals

, ,. , ,

showing a distinct rod shape,
enables us to determine that
Fig. 71.— Pneumonia bacilli all the cells are bacilli, for if
x 70°- we had to do with the forms

a. from cultivations. i • i j j

ft, from exudation showing which we are accustomed to
capsules. designate as cocci, we should

only find round, or at most very slightly oval cells.

The short bacilli grow very frequently in chains of two
to four members ; these forms are apparently the more
numerous, the more rapid is the multiplication, and
hence in these preparations the short forms show a
marked preponderance.

In preparations which are obtained from the animal
body, but not in those taken from cultivations of the
bacilli, the organisms are surrounded by a sort of
staining of capsule. Each bacillus lies embedded in a gelatinous
the capsule. gkeath which is evidently composed of a substance
similar to mucine, as shown by its solubility in dilute
alkalies, and its insolubility in acetic acid ; the sheath
stains faintly when treated in a certain manner with
gentian violet or fuchsine, and is thus rendered very
distinct. In order to demonstrate the capsules dis-
tinctly in sections, Friedlander recommends the follow-
ing method : place the sections for twenty-four hours
in acid gentian violet solution (concentrated alcoholic
solution of gentian violet 50 parts, distilled water
100 parts, acetic acid 10 parts), then decolourise in
*1 per cent, of acetic acid for one to two minutes ;
then treat with alcohol, oil of cloves, &c. Ribbert
employs for cover glass preparations a staining fluid
composed of 100 parts of water, 50 parts of alcohol, 12 £
of glacial acetic acid, saturated, when warm, with dahlia ;
the preparations are immersed in this solution only for
a very short time, then washed in water and examined.

BACILLUS PNEUMONLE. 25

The sheath has exactly the form of the bacillus which it
surrounds, and hence it usually presents the appearance
of an elongated ovoid ; two to four bacilli in chains are
often present in one capsule ; in other cases the division
is complete, and each of the new bacilli has its own
capsule. The breadth of the sheath is at least as great
as the transverse diameter of the bacilli ; at times, how-
ever, it is two to three times greater. This capsule
formation is not at all peculiar to the pneumonia bacilli,
in which, however, the enveloping substance which is
present in a very large number of bacteria is particularly
well formed ; this material is also quite as great in some
other species.

Cultivations of Friedliiuder's bacilli are readily obtained Cultivations,
on very various nutrient substrata. On gelatine plates
white points appear after twenty-four hours, and under
the microscope present the form of round, sharply-
defined discs, with a dark granular centre, and a narrow
olive-coloured border ; at a later period a white por-
cellaneous deposit is formed on the surface of the
gelatine, like a very prominent convex knob. In cultiva-
tions made by plunging the needle into the gelatine, a
thick, white, confluent mass is formed along the track
of the needle, and this mass extends into any fissures
which may communicate with this track ; here, also, we
iind a convex knob on the surface. In stroke cultivations
& thick, white, creamy layer is formed. — The bacillus
also grows well on agar, blood serum, and potatoes. On
the latter whitish-yellow gelatinous masses are formed,-
which may extend over the whole surface of the potato,
presenting a glistening surface and showing at times a
•development of gas and formation of bubbles. — The rod
shape of the bacilli is particularly evident in micro-
scopical preparations of cultures, especially when the
growth has occurred at a low temperature and the
individual organisms have attained their full size before
dividing. The formation of spores has not as yet been
observed with certainty.

Friedliinder and Frobenius have performed inocula- r

, • . . , . . . Inoculation on

tion experiments on animals with pure cultivations of the animals.

17

258 BACILLI PATHOGENIC IN MAN.

bacilli. If fluids containing the cultures were injected
through the wall of the thorax into one lung of &
rabbit by means of a Pravaz syringe, no disease occurred,
rabbits being completely refractory to the organisms.
On the other hand, 32 mice treated in the same way
died ; on post-mortem examination reddish, turbid fluid
was found in both pleural cavities, both lungs were very
markedly reddened, almost completely devoid of air, and
showed scattered and ill-defined patches of red infiltra-
tion. Of 11 guinea-pigs, 6 showed similar appearances;
of 5 dogs, 1. If the cultivation was exposed to a
temperature of about 80° C. for 15 to 20 minutes, and then
injected into mice, the animals remained healthy, with
the exception of a few, where the injury was uninten-
tionally more severe. (This is a control experiment,
which in view of the serious injury done by such injec-
tions into the lungs of mice was absolutely necessary,
and still requires further repetition). — Five mice were
also successfully infected by inhalation of cultivations,
and these, in like manner, presented typical appearances
of pneumonia. The same organisms could be cultivated
from the affected lungs of the animals experimented on*
Significance of In judging of the significance of Friedlander's pneu-
mom'a bacilli, more especially for the purpose of clinical

etiology of diagnosis, it is very important to note that they cannot
be distinguished with certainty from a number of other
organisms, either by their microscopical characters, or by
their cultivations. The same morphological characters —
even the capsules — are present in a number of bacteria ;
the character of the cultivations is extremely common,.
and shared by many species of bacteria; both the morpho-
logical and cultural characteristics were combined in
bacilli studied by Passet, Kreibohm, and others. Hence-
a definite diagnosis of these organisms is only possible-
by experiments on animals; and even in this respect
the distinction is difficult, because other organisms also-
show similar pathogenic action to that of Friedlander's
bacilli (for example, the bacillus isolated by Schou).
The allied pathogenic bacteria which have been as yet
isolated in a. similar manner show, however, differences

BACILLUS PNEUMONLE. 259

/

with regard to their growth in gelatine and with regard
to the species of animals susceptible to their action, and
these differences enable us to distinguish them from
Friedlander's bacilli. But the diagnosis of the latter
can only be made by the aid of elaborate comparative
cultivations and experiments on animals. And hence
the establishment of a causal connection of these bacilli
with pneumonia, based on their distribution in pneumonic
processes, is very difficult, because it is not possible in
every case to employ all the methods which alone enable
us to distinguish these organisms from others which are
constantly present in the sputum and in the bronchi,
and which are therefore frequently found in pneumonic
exudation, although they are of no importance.

The answer to these questions is so much the more
difficult because Friedlander's bacilli are, without doubt,
not the only cause of the pneumonic process. We are
already acquainted with pneumonias which are caused
by aspergillus and actinomyces ; it is a priori not im-
probable that also among bacteria there are several other
species which can set up pneumonia ; and the probability
of this view is increased by Schou's observations. Further
careful observations, combined with cultivations and ex-
periments on animals, will therefore possibly discover a
greater variety of causes of pneumonia.*

Emmerich has demonstrated the presence of Fried- Occurrence of
lander's bacilli in the soil of a room in which there were ba
many pneumonic patients ; the diagnosis was rendered the human
certain by inhalation experiments with cultivations on
18 mice, of which 8 died of pneumonia ; hence the soil
seems to be one of the places where the pneumonia
bacilli can be preserved, and whence, in suitable cases,
they may pass into human beings. Possibly also there
are a number of other places in our surroundings which
play a similar r6le. But as the result of our present
knowledge as to their occurrence and their properties,
we cannot make any more definite statement with regard
to the mode of spread of these pneumonia bacilli.

* Friinkel has isolated a bacillus which is much more often associated
with pneumonia than the above-mentioned organism.

260

BACILLI PATHOGENIC IN MAN.

Demonstra-
tion of the
inoculability
of tuber-
culosis.

Method of
demonstrat-
ing1 the
tubercle
bacilli micro-
scopically.

Bacillus tuberculosis.

Klencke, and at a later period Villemin, were the
first to show that the affected organs from tuberculous
human beings, and from animals suffering from perl-
sucht, set up tuberculosis when inoculated on animals ;
they thereby proved the infective nature of tuberculosis,
and provided a justifiable basis for the supposition that
in this disease also the exciting agent was an organised
living body. The infective experiments were subse-
quently repeated in a convincing manner, more espe-
cially by Cohnheim and Salomon sen, and later by
Darnsch, who employed the eyes of rabbits as the seat
of inoculation, and were able to set up tuberculosis of
the iris by inoculation of tuberculous material into the
eye, the disease spreading from thence to other organs.
In spite of these experiments the nature and the ulti-
mate cause of tuberculosis was for a long time obscure,
as the attempts to find, even with the most careful
microscopical examination, any organised bodies in
tuberculous organs which could be looked on as the
exciting agents of the disease were not successful, and
as also experiments on the cultivation of the sup-
posed organised virus did not lead to any definite
result. It was not till a few years ago that by means
of Koch's classical investigations we obtained a com-
plete insight into the etiology of this disease ; a result
which so much the more deserves our most complete
admiration , because entirely new and special methods
were necessary as well for the microscopical examina-
tion as also for the cultivation of the micro-organisms,
and because the whole investigation was laid before
us in such a complete form that in respect of this
question the points as to the etiology of tuberculosis
are scarcely capable of any further important expansion.
The following description is consequently in the main
based only on Koch's work on tuberculosis.

In the first place Koch succeeded in demonstrating
the presence of peculiar bacilli in the most various
tuberculous affections by means of a special method of
staining. While no micro-organisms could be demon-

BACILLUS TUBERCULOSIS. 261

strated by the aniline stains as ordinarily employed,
nor by the other nuclear stains, organisms at once
became quite evident when a small quantity of alkali
was added to the solutions of the aniline colouring
matters. As later investigations showed, the substi-
tution of anilin, toluidin, turpentine, carbolic acid, or
ammonia, for the alkali acts in a similar mannner in
enabling the staining material to penetrate into the
tubercle bacilli ; even without any such addition to the
staining fluids, the bacilli may be successfully stained
if only the action of the staining material is sufficiently
intense to show quantitative differences with respect to
the taking up of the colouring matter. It is also of
special advantage that the staining material once it has
penetrated into the bacilli is held very tenaciously;
Koch found that on treatment of sections stained in
the alkaline colouring material with strong nitric acid
or hydrochloric acid the colouring matter is extracted
from cells, nuclei, and all other bacteria, while the
tubercle bacilli alone remain stained. In the tissue,
which is now colourless, the individual bacilli are re-
markably easily recognised on account of their stain;
and the picture may be further improved by treating the
section, after the employment of the decolourising means,
with an ordinary nuclear aniline stain, the tone of which
presents a good contrast to the solution first employed
for the staining of the tubercle bacilli. The cell nuclei
and also the other bacteria (not tubercle bacilli) take on
this second stain, so that, for ' example, the tubercle
bacilli appear red, the cell nuclei and other bacteria
blue, or the former violet, and the latter brown. (As to
the modifications and the technique of the method of
staining tubercle bacilli, as well as with regard to the
exceptions to the exclusive staining of the tubercle
bacilli, see the chapter on "Methods."

The bacilli found in tuberculous organs by the aid Morphological
of this extremely sharp and sensitive method are rods ° ara(
1*5 — 3'5 p. in length; their breadth is constant when
the same staining methods are employed, and corre-
sponds to that of the bacilli of mouse septicaemia. For

262 BACILLI PATHOGENIC IN MAN.

the most part the bacilli are slightly bent, or even more
frequently curved. They are often spore-bearing, the
number of the spores being usually 2 — 4 or even 6. By
the ordinary method of treating the preparations the
spores do not take up the colouring matter, and hence
the spore-bearing bacillus when stained presents the
appearance of a dark thread, interrupted by clear egg-
shaped spaces. At times it seems as if the spores pro-
jected laterally beyond the con-
tour of the bacillus. If the
specimen is examined with in-
sufficient magnification one
readily obtains the impression
that such a spore-bearing thread
is composed of a chain of cocci ;
if the preparation is badly
stained, too much heated, or too

Fig. 72.— Sputum containing long treated with acid, this ap-
pearanceisincreased. Neverthe-
less it is always possible, in carefully prepared specimens
and with the aid of good lenses (Zeiss rV, Winkel ^V),
to convince oneself that the supposed chain of cocci does
not exist, but that the delicate contour of the bacillus
can be for the most part traced through its whole length,
and that it is only within this contour that the alter-
nation of stained and unstained zones gives the deceptive
appearance of stained cocci separated by narrow inter-
mediate spaces. The assertion made by some observers
that the tubercle bacilli also occur in the form of cocci
can only be referred to this and other errors of obser-
vation. In all cases the tubercle bacilli appear
to be non-motile. ft ^

situation of The bacilli are most readily found where the J (J
tubercular process is commencing or spreading.
At first the bacilli are single, and then almost Fig 73.—
always lie in the immediate neighbourhood of a bacilli x
nucleus and in the interior of the cell to which 120°-
this nucleus belongs ; later they occur in closely packed
small masses. The cheesy centre of the mass shows
only broken down nuclear substance, which no longer

BACILLUS TUBERCULOSIS,

263

takes on the nuclear stain, and in which there are very
few or no tubercle bacilli; from the infectivity of the

Fig 74. — Miliary tuberculosis
of the lungs X 700.

Fig.

75. — Tuberculosis of the
intestine X 700.

cheesy centre the conclusion may, however, be drawn that
the bacilli have here passed into the spore stage, which
cannot be demonstrated by staining.

As soon as giant cells appear in the tubercles, tubercle
bacilli are almost al-
ways found in them . /^1
They often contain
only one bacillus,

and then a peculiar
antagonism is fre-
quently evident
between the nuclei
of the giant cells
and the enclosed
bacillus. The latter
takes up a position
opposed to the
nuclei, and lies as

<HK? |
III

W.

Fig. 76A. —Giant cell from a case of miliary
tuberculosis X 700.

far as possible in the part of the cell which is free from
nuclei (fig. 76fi). If the number of tubercle bacilli
which develop in the giant cells increases markedly, they
finally break through the wall of nuclei, and the giant
cell then apparently dies.

264

BACILLI PATHOGENIC IN MAN.

tubercular
affections.

The bacilli are probably first introduced into the
diseased tissue by wandering cells which take up and
transport the bacilli, which are not themselves capable
of independent movement • it is possible that this trans-
porting wandering cell becomes then transformed into
an epithelioid cell and afterwards into a giant cell. In
many infective experiments wandering cells containing
tubercle bacilli can be directly demonstrated in the blood
and tissues.
Distribution Koch examined in man 19 cases of miliary tubereu-

of the bacilli -, . ., , . , .. , ....

in the various 1( !1S> m no"e ot which the bacilli were missing from the

tubercular nodules :
29 cases of phthisis
of the lungs (8 com-
plicated with intes-
tinal tuberculosis) ;
here also the bacilli
were constantly
found, and apart
from the sputum
they were most
numerous in fresh
cheesy infiltrations
and in the interior
of cavities where the
walls were rapidly
breaking down. In
tuberculous ulcers

Fig. 76s. — Giant cell containing a
tubercle bacillus ; section from lupus
of the skin X 700.

of the tongue, in tuberculosis of the pelvis of the kidney,
of the uterus, of the testicle, &c., the bacilli were con-
stantly found ; likewise in 21 cases of tuberculous glands.
Farther, they were present in 13 cases of tuberculosis
of the joints and 10 cases of tuberculous affections of
bones ; in 4 cases of lupus, where the bacilli were only
found in giant cells, and only one organism in each ; in
7 cases of bovine tuberculosis ; finally, in various animals
inoculated with tubercular material (273 guinea-pigs,
105 rabbits, 44 field mice, 28 white mice, 19 rats, 13 cats,
as well as dogs, marmots, fowls, pigeons, &c.). Further,
sputa and organs in a very large number of other non-

BACILLUS TUBERCULOSIS. 265.

tuberculous affections were examined ; here, however,
the characteristic bacilli were invariably absent.

From all these microscopical investigations it follows
with certainty that the tubercle bacilli occur constantly
and exclusively in tuberculosis, that they precede the
pathological alterations which are peculiar to tubercu-
losis both in place and time, and that their number, their
appearance, and their disappearance, stand in direct
relation to the course of the disease. These results
evidently imply an etiological relation between the
tubercle bacilli and the tubercular process.

The cultivation of the tubercle bacilli was also ac- Cultivation of
companied, like their microscopical demonstration, Bacilli. °
by special difficulties, and required new and special
methods. No growth occurred on the ordinary nutrient
media. The tubercle bacilli evidently lead a parasitic
existence, and saprophytic growth can only occur when
the conditions under which they flourish in the animal
body are copied as accurately as possible ; as also the
whole development of the tubercular process only goes
on very slowly we can only expect a difficult and slow
growth of the bacilli, even under conditions which
to some extent correspond with those which are present
i;i the animal body. As a matter of fact Koch only suc-
ceeded in obtaining cultivations when he employed
blood serum, gelatine, or solidified blood serum kept at
the body temperature, and when also these nutritive
media were so prepared that they could be kept for 14
days or longer at the body temperature without drying
up, or becoming contaminated with other organisms.
It was found that blood serum kept in test tubes, and
sterilised, was the most suitable material, especially
when the tubes were kept in an oblique position while
the blood serum was solidifying, and thus a large
surface was presented for the growth of the cultivation.
(More accurate details as to the preparation of this
nutrient medium will be given in the chapter on
" Methods.") During solidification of the blood serum
the condensed water collects in large drops at the lowest
part of the oblique surface of the serum, and this reser-

266

BACILLI PATHOGENIC IN MAN.

voir of water is in so far of importance for the cultiva-
tion, as by means of it the surface of the serum is kept
sufficiently moist, and preserved from drying during the
long time that it is kept in the incubator.

If tubercular masses are placed on such nutrient
substrata (care being taken completely
to exclude other bacteria), and kept
permanently at 37° C., distinct multi-
plication of the tubercle bacilli can be
seen after about 14 days. The greatest
care must of course be employed to ex-
clude other bacteria, more especially
because the saprophytes as a rule grow
much more rapidly at the body tern-
perature, and, starting from a very small
number of individuals, may completely
occupy the surface of the soil before the
tubercle bacilli have even begun to
multiply. According to Koch, it is best
to commence the cultivations from the
lymphatic glands of a guinea-pig which
has been inoculated with tubercular

F; s: •;;;.;:: i-;;., ,\'M

sputum or tubercular organs, and has
been killed after about three or four
weeks. The skin is purified with cor-
rosive sublimate, and one of the swollen
lymphatic glands is exposed, a series of
heated knives and scissors being em-
ployed for the purpose.

Finally, the gland is cut through and
a portion of the interior is rubbed over

Fig. 77.— Cultivation x , n

of tubercle bacilli the surface of the blood serum. In
on blood serum. gpite of tliese precauti0ns, it is always

well to inoculate a considerable number of tubes, for
some always become contaminated and useless. In the
incubator the tubes remain unaltered for 7 to 10 days ;
after this time, sometimes not till the fourteenth day,
dull white points and small flakes are formed on the
surface of the serum, these flakes having the appearance
of dry scales with a dull surface. At times they unite

BACILLUS TUBERCULOSIS. 267

to form a thin, dull covering over the surface of the
serum. On further inoculation of these cultivations on
new blood serum the growth takes place more readily ;
later cultivations give more luxuriant growths, which
also spread over the surface of the drop of fluid present
at the lower part of the tube. When
examined under a low power of the
microscope (80 diameters) the appear-
ance of the colonies is seen to be
very peculiar and characteristic. After
five to six days very peculiar and
delicate figures are seen on the
surface of the blood serum, forming
finely curved and S-shaped lines ; Fig 78 .Lcolonies of
these gradually spread and form tubercle bacilli from

J . a cultivation, dried

masses which ultimately become and stained on a
united with one another. These
colonies can be obtained by pressing a cover glass on
the surface of the serum, and they can then be stained
and the individual bacilli recognised under high powers
of the microscope.

Koch has made in all 43 cultivations from tubercular
material ; several of these being from bovine tuberculosis,
scrofulous glands, fungous disease of joints, and lupus.
Some of these cultivations have been now kept up
through more than forty generations for over three
years ; but the bacilli have in no way lost their viru-
lence.— Another soil on which they can grow is a mix-
ture of infusion of meat with agar, but the growth on
this material is by no means so good. Koch was only
able to obtain a cultivation in neutralised meat infusion
under special conditions, and in -this material the
bacteria formed, after four or five weeks, a white,
granular deposit at the bottom of the clear fluid. No
growth could be obtained on any vegetable substance.
The development of the bacilli completely ceases below
28° or 29° C. ; at 30° C. it is very slow; it is best
between 37° and 38°, and completely ceases at 42°.
The difficulty of cultivation and the narrow limits with- Cultivation
in which growth occurs has been confirmed by other h/fanS?*8

observers.

268 BACILLI PATHOGENIC IN MAN.

observers, and this fact shows that the supposed pure
cultivations of tubercle bacilli carried out by earlier
authors, and not under the conditions mentioned above,
were not pure cultivations, but were cultivations of some
accidental saprophyte.
Experiments From these cultivations Koch has infected numerous

on animals. . •,-,-, T

animals, and thus completed the necessary proof. In
the first place he has in many cases repeated the former
infective experiments with tubercular tissues. For
example, 179 guinea-pigs, 35 rabbits, and numerous
other animals were inoculated with nodules from
miliary tuberculosis, with phthisical sputum, with pus
from tubercular abscesses, with the material from
fungous disease of joints, with scrofulous glands, with
lupus, and with nodules from bovine tuberculosis, and
in all the cases tuberculosis occurred.

inoculation The infection occurs most easily by introducing a
lar sputiTmCU" little sputum into a pocket in the skin over the
abdomen of guinea-pigs. The wound is closed with a
stitch, soon heals, and usually shows no reaction.
After two to three weeks, however, swelling of the
nearest lymphatic glands occurs ; at the same time the
seat of inoculation becomes hard, and a nodule is
formed. This nodule subsequently ulcerates, and
becomes covered with a dry crust, under which is a
shallow ulcer with cheesy base. The animals become
thin, they have difficulty of respiration, and generally
die in from the fourth to the eighth week. — In rabbits
the course of the disease after such an inoculation is not
so definite; it is best here to inoculate into the anterior
chamber of the eye.

infection by Koch has further made numerous inoculations with

tk>n°sof tuber- pure cultivations. For this purpose animals freshly

cie bacilh. bought were employed ; they were kept in a special

cage, killed in the early stage of the disease, and in

order to exclude, as far as possible, all suspicion of

accidental tuberculosis, uninoculated control animals

were always kept beside them. The pure cultivations

were inoculated in a variety of ways ; in the first place

subcutaneously. As a result, all the guinea-pigs and

BACILLUS TUBERCULOSIS. 269

field mice died, also one marmot. Fowls were in part By subcutane-
susceptible ; white mice were almost altogether insus- tkm!™
ceptible. A second mode of infection was the inocula- By inoculation
tlon of the pure cultivations into the anterior chamber of ^eriorcham-
the eye in rabbits. An incision several millimetres in ber of the eye-
length was made at the upper border of the cornea, and,
by means of a blunt hook, a minute fragment of a pure
cultivation was pushed into the anterior chamber, or a
mixture of the cultivation in water was injected by
means of a syringe which possessed a fine, sharp
canula. If by this mode of infection few bacilli were
injected, tuberculosis of the iris occurred somewhat
more quickly than after the introduction of tubercular
tissue. This was followed by swelling and caseation of
the nearest lymphatic glands, and subsequently by
tubercular infection of other organs. Where large
quantities of bacilli were injected, however, caseation of
the bulb and general tuberculosis rapidly occurred, so
that the lymphatic glands were, as it were, passed over
by the infection.

In a third series of experiments, a mixture of the By injection
cultivations was injected into the peritoneal cavity. By Abdominal
this mode of infection, animals which were otherwise cavity-
very insusceptible to the disease — such as dogs, rats, and
white mice — died with extensive eruption of tubercles
in the abdominal organs. Fourthly, mixtures of the By intra-
cultivations, which had been filtered through fine Ejection,
gauze, were injected into the veins (the jugular or
aural vein). By this method the most rapid and most
complete infection was obtained, an enormous number
of tubercular nodules appearing in a much shorter time
than is ever the case in spontaneous tuberculosis. In
these experiments, therefore, the possibility of spon-
taneous tuberculosis can be excluded most readily, and
with the greatest certainty.

Lastly, Koch attempted to introduce the cultivations By inhalation,
of bacilli into the animals by inhalation. The mixture of
the cultivations with water was sprayed by means of a
hand spray into the interior of a box standing in the
open air, and in this box 20 to 30 rabbits, guinea-pigs,

270 BACILLI PATHOGENIC IN MAN.

rats, and white mice were placed. The animals were
then kept in a special cage and well tended ; after 28
days they were killed, and all showed extensive tuber-
culosis.

The inoculations were made on a total of 217 animals.
The more susceptible animals — guinea-pigs, field mice,
rabbits, and cats — died as the result of all the different
modes of infection ; and where large numbers of bacilli
were employed, dogs, rats, and white mice were also un-
able to withstand their action.

Control It must also be mentioned that numerous control ex-

periments were made with a great variety of cultivations
and mixtures of other bacteria, and that the inhalation
experiments were also controlled by Koch in a similar
manner. Nevertheless, in no case was tubercular
disease observed in these animals.

The proof that we must look on the tubercle bacillus
as the only and all-sufficient cause of all kinds of tuber-
cular diseases has thus been brought by Koch with a
completeness and certainty which has scarcely ever been
attained as regards the etiology of any other disease.
The results of Koch's experiments have been subse-
quently confirmed completely by several observers ; thus
the whole series of investigations has been repeated by
Watson Cheyne, Rosenbach, the author, &c. The
constant and exclusive occurrence of the tubercle bacilli
in tubercular diseases has been confirmed by numerous
observers, more particularly their occurrence in
phthisical sputum, and also in the surgical tubercular
affections in lupus, bovine tuberculosis, &c. The
objections which have been raised by Formad, Spin a,
and others, against the etiological significance of the
tubercle bacillus, or against certain parts of the proof
furnished by Koch — for example, against the specific
applicability of the methods of staining, against the ex-
periments on animals, &c. — have been shown to be
badly founded in every respect, and have for the most
part arisen only from imperfect employment of Koch's
methods.

BACILLUS TUBERCULOSIS. 271

From the knowledge which we have obtained, as the Deductions as
result of experiments, with regard to the biological g^fa"^6
relations of the tubercle bacilli, important conclusions may tuberculosis,
be drawn as to the mode of spread of these bacilli, and of
the disease caused by them. In our ordinary surround-
ings the conditions necessary for the multiplication of
the tubercle bacilli are, without doubt, never present ;
in other words, they do not possess a saprophytic stage
of existence, but they always behave as true parasites
under the conditions which are present in nature.
Hence the spread of tuberculosis could only occur by
infection from individual to individual, were it not that
the bacilli can retain their vitality and all their virulent
characters for a considerable time outside the body. This
preservation of the organisms is aided to a great degree
by the presence of spores, which have proved, as the
result of direct experiments, to be very resisting.
Sputum, containing spore-bearing tubercle bacilli, was Length of life
still virulent after six weeks, although it was kept moist, £f tjje tubercle
and although putrefaction occurred in it ; such sputum
when dried retained its virulence up to 186 days, as was
proved by the inoculation of guinea-pigs. Hence we
may assume that our ordinary surroundings must be
frequently much contaminated with virulent bacillus
spores, and that infection can occur not only directly
from the patient, but also by means of the most various
objects from his surroundings, often in a very indirect
manner and after a relatively long time. The most Distribution
important source of the contamination of our surround- by means of
ings with tubercle bacilli is undoubtedly phthisical
sputum; as almost one-seventh of mankind die of
phthisis of the lungs, and as a large portion of tho
sputum is constantly dried in the clothes and on other
objects, and thus is able to pass into the dust, the
distribution of the virulent material must be compara-
tively great.

Nevertheless numerous experimenters have failed to
discover any tubercle bacilli in the air, even of places
such as wards in which phthisical patients were con-
stantly present (Celli and Guarneri, Bellinger), and only

272

BACILLI PATHOGENIC IN MAN.

Futile at-
tempts to
demonstrate
tubercle
bacilli in the

Reasons for
the negative
results.

Modes in
which the
tubercle
bacillus
enters the
bodv.

one observer (Williams) was able to demonstrate, by means
of the microscope, tubercle bacilli in the air obtained
from the ventilation shaft of a consumption hospital.
These failures are, however, by no means sufficient to
cause us to modify our convictions as to the wide distri-
bution of virulent tubercle bacilli or spores ; our methods
are, on the contrary, much too imperfect to enable us
to demonstrate with certainty bacilli in air, which,
nevertheless, when inhaled, might introduce a number
of these organisms into the body sufficient to produce
infection. The examination of air with this view can be
carried out by means of microscopical investigation, by
cultivation, or by infection experiments. As regards the
first method, we have already learned in the case of
other fungi that by means of it we can only recognise a
very small percentage of the bacteria which are really
present, and that a negative result is obtained even in
those cases where we are able to demonstrate the presence
of numerous individuals bj* means of cultivation. With
regard to the tubercle bacilli also, the investigation by
means of cultivation, which is otherwise very useful and
much more sensitive, cannot be employed for these
experiments, because, as the result of the slow and
difficult growth of the tubercle bacilli, the soil is always
completely occupied at an earlier period by other unavoid-
able bacteria, and also because for infective experiments
we require larger numbers of bacilli, and more especially
a more concentrated material than is obtained by these
investigations of the air, and hence it is not correct to
conclude that because infection has not occurred the air
investigated has been free from tubercle bacilli. Where
a longer time is spent in rooms contaminated by
phthisical sputum, &c., and where the air of these
rooms is breathed for some time, the entrance of the
respiratory tract comes into contact with many more
bacilli than can as yet be demonstrated by means of any
mode of aeroscopic investigation.

The tubercular virus without doubt enters the body
most frequently with the inspired air, and this is the
mode in which healthy persons are most commonly

BACILLUS TUBERCULOSIS. 273

Infected with tuberculosis; in rare cases the tubercle
bacilli may also penetrate into the body through wounds
of the skin. At times tubercular animals are the source
of the infection ; but the disease seems only to be carried
by the milk of tubercular cows when the mammary
glands are themselves affected with the disease.

In apparent contrast to the influence of the local
spread of the tubercle bacilli, we have the experience
that as the result of living in the neighbourhood of
tubercular individuals by no means all the healthy
persons are infected; indeed, the percentage of infections
is only slightly greater than where there is, as far as we
can judge, much less opportunity for infection. The Important

,. ... ., rl , J .j . part played bv

predisposition evidently plays a very important role in the individual
the occurrence of tubercular infection ; it practically j^ lsposl"
controls the mode of spread of the tuberculosis, and is
more especially important because it has the greatest
influence on the treatment of the disease. What this
individual predisposition consists of is a question which
has been as yet very little investigated as regards its
relation to the infective agents which have as yet been
recognised. We know that there are certain protective
arrangements in the body which, along with the very
limited conditions of life of the tubercle bacilli, render it
difficult for the latter to obtain a foothold ; in this respect
we may point out the moist and sticky lining membrane
at the entrance to the respiratory tract, the mode in
which elements which have passed further are expelled
foy the ciliated epithelium and by coughing, and the
resisting power of the normal cells, more especially of the
epithelial cells (Veraguth), towards the individual para-
sites. It is only when, for example, as the result of
chronic catarrh, there are lesions of the epithelial covering,
or when there is stagnation of the secretion in certain
parts of the lung, or when the nutrition and the energy
of the epithelial cells is defective, that the bacilli which
have entered can develop and multiply undisturbed ; and
these conditions again chiefly occur only in individuals
in whom the thorax is abnormal or where the nutrition
is bad, or in those who do not breathe sufficiently deeply,

18

274 BACILLI PATHOGENIC IN MAN.

or again in those where, as the result of their employ-
ment, there is constantly irritation of the respiratory
mucous memhrane. In how far, however, these supposed
predisposing causes can be experimentally proved, or
can be brought into unison with clinical experience,
must be for the present left in doubt.

Bacillus lepra.

In all forms of leprosy (Lepra tuberculosa, maculosa,
and anassthetica), and quite apart from the country in
which the disease has been acquired, whether in the
East, in Norway, or in other places where it is endemic,
we find in the affected organs numerous characteristic
bacilli, which were first described by Armauer, Hansen,
Occurrence of and Neisser. These bacilli have been demonstrated in
bacilli. the leprous tumours of the skin, in the mucous mem-

brane of the mouth, palate, and larynx ; further, in the
peculiar interstitial affections of the peripheral nerves,
of the cornea, cartilage, and testicle ; in the lymphatic
glands, spleen, and liver ; in the anaesthetic form of
leprosy, for example, in the thickened ulnar nerve ; and
lastly, on several occasions, in the blood of lepers. On
making sections through the cutaneous nodules we see
that the tissue is infiltrated with numerous small round
or oval cells, which are more or loss completely filled
with bacilli ; the latter often lie in a thick mass in
various directions, they often appear arranged in a more
or less ray-like form radiating from the centre of the
cell ; at times they form parallel bundles. In the older
tumours the so-called true lepra cells are present in
large numbers, these cells being large, multi-nucleated,
and similar to giant cells, and also containing very
numerous bacilli in their interior. In part, however,
the bacilli also lie outside the cells in the lymphatic
spaces. Kecently Unna states that he has convinced
himself, from the examination of dry sections, that the
supposed cells containing bacilli are only masses of
bacilli which are held together by gelatinous material,
and that the greater number of the bacilli are free, and

BACILLUS LEPRE. 275

lie usually in globular masses in the lymphatic channels ;

but these statements require further proof in view of the

unusual mode of investigation employed by Unna. — The

epidermic layer of the skin is

always free from bacilli ; Babes

alone has pointed out the presence

of bacilli in the hair follicles, and

in the sebaceous glands of the

hair, and has thus shown that it

is possible that the organisms may

in this way reach the surface of the skin.

The bacilli are 4 to 6 /*. in length, and less than Morphologka
1 A*, in breadth, resembling on the whole the tubercle characters-
bacilli, but not so irregular as regards length as these,
nor so often curved. Spores seem to be generally present,
but they are not so distinct as in the case of the tubercle
bacilli. The leprosy bacilli can be distinguished from
the latter by the fact that they take up the ordinary
aniline stains and the nuclear stains much more readily
than the tubercle bacilli. They can, however, be stained
in the same manner as the tubercle bacilli ; like these,
the leprosy bacilli alone among all the bacteria hold an
alkaline aniline stain, or one containing aniline oil, so
energetically that it is not removed on treatment with
strong acids. Hence in the case of the leprosy bacilli
we can employ the same method of double staining as.
in the case of the tubercle bacilli. The bacilli can be
stained red and the tissue blue, or violet and the tissue
brown. This is the best method of staining sections of
leprosy, and it shows most distinctly the individual
organisms. If we wish to distinguish between leprosy
bacilli and tubercle bacilli we place a dried cover glass
preparation for six to seven minutes in a dilute alcoholic^
solution of fuchsine, decolourise for a quarter of a minute
in acid alcohol, wash in distilled water, and stain with
methylene blue. When treated in this way the leprosy
bacilli appear red on a blue ground, while the tubercle
bacilli have not taken up the red stain in this short
time (Baumgarten).

All attempts at cultivation of the leprosy bacilli have

276

BACILLI PATHOGENIC IN MAN.

Cultivation
experiments
and experi-
ments on
animals.

been as yet in vain. Even after being kept for fourteen
days on solidified blood serum at 37° C. no, growth can
be observed. — In like manner, attempts to communicate
the disease to animals have met with great difficulties,
although on several occasions a slight spread of the
leprous process from the particles introduced to the
normal tissue has been seen. Thus Damsch observed,
in the case of two rabbits after inoculation of a piece of
a tumour into the anterior chamber of the eye, that
after five weeks in both animals the iris and the ciliary
body were infiltrated with dense lines of large cells con-
taining bacilli, and that deposits appeared on Descemet's
membrane, and on the anterior capsule of the lens, which
consisted of round cells containing bacilli. In like
manner a successful attempt has been made to inoculate
the leprous tumours into the peritoneal cavity, and under
the skin of two cats. In the latter case the cats were
killed after 120 days ; on making an examination it was
seen that the tumour had become flattened and shrunk in
the subcutaneous tissue, and that it was surrounded and
fixed to the skin by a brownish tissue of new formation,
which contained numerous cells filled with leprosy
bacilli. Vossius repeated the experiment of introducing
pieces of tumour into the anterior chamber of the eye in
rabbits, and likewise observed multiplication of the
leprosy bacilli, and their penetration into the iris and
cornea. But in none of the cases did the process spread
further, nor was the clinical picture of leprosy produced ;
;-and in many other experiments even the infection of the
neighbouring tissue has failed. Thus attempts which
were made by Damsch to inoculate the disease sub-
cutaneously in mice and rabbits, by Vidal in a pig, by
Kobner in frogs, eels, &c., were entirely without result. —
In the case of man also, the spread of the disease by
infection is extremely rare, and is evidently only possible
under very special predisposing circumstances.

In spite of the great blanks in our knowledge with
regard to the leprosy bacilli, we must look on these
organisms as undoubtedly the cause of the disease,
because they occur constantly and exclusively in this

BACILLUS MALLEI. 277

affection, and because also they are present in enormous
numbers, and practicalJy form the greater part of the
affected tissue in the leprous organs.

Bacillus mallei.
(Glanders, Rotz, Morve.)
Although several observers have described the occur- Historical

,. . p i 3 t\' facts as to the

rence of micro-organisms in cases of glanders, nothing discovery of
certain was ascertained as to their etiological significance ^§}fnders
till Loeffler and Schiitz succeeded, three years ago,
in completely clearing up the etiology of this disease by
the demonstration of characteristic bacilli in the glanders
nodules, by the cultivation of these bacilli on artificial
substrata, and by the inoculation of the cultivations on
various animals with the production of the typical
disease. Almost at the same time Bouchard, Capitan
and Charrin made cultivations in broth from an abscess
in a man suffering from glanders, and from the ulcers of
a horse, and, after several generations, inoculated these
cultivations with success on asses, cats, and guinea-pigs ;
but these observers found in their cultivations only
round organisms, at times occurring in chains, and they
looked on these as the active exciting agents of the
disease. About the same time also Israel made culti-
vations on blood serum from the glanders nodules of three
horses, and was able to set up glanders in rabbits by
means of these cultivations ; Israel obtained bacilli in
his cultivations corresponding with those isolated by
Loeffler and Schiitz. At a later period Kitt and Weich-
selbaum have made cultivations and inoculations of the
glanders organisms, and both of these observers were
able to confirm, in the main, the statements made by
Loeffler and Schiitz ; Weichselbaum obtained the
material for his cultivations from a man suffering from
acute glanders.

The bacilli which have been described by all the Morphological
observers— with the exception of the French investi- TheS
gators before mentioned — are thin rods, similar to the bacilli-
tubercle bacilli, but more uniform in size, and somewhat

27B

BACILLI PATHOGENIC IN MAN.

broader ; like these they are often slightly curved. One
can almost always observe in stained preparations that
the individual bacilli are composed of dark and clear
zones, so that under a low power they may resemble a
chain of cocci; but when higher powers are employed
this impression is seen to be incorrect. The clear un-
stained spaces are probably spores. The bacilli lie in
part singly, in part they are united in bundles of 4 to
8 parallel rods, in part they lie in confused masses.
It is by no means easy to stain these organisms well in
sections ; the glanders bacilli take up the aniline stains

Fig. 80.— Glanders bacilli.

a, section from a glanders nodule X 700.

b, bacilli of glanders stained with methylene blue X 1,500.

with some difficulty, and further the dense accumulation
of strongly staining nuclei in the glanders nodules
renders the discovery of the bacilli difficult. The best
plan is to stain with alkaline methylene blue for 12
to 24 hours, then to treat the specimen cautiously
with very dilute acetic acid till the decolourisation has
so far advanced that the bacilli can be distinctly seen.
After such treatment we find, here and there, clearer
parts in the tissue where the masses of glanders bacilli
can be seen particularly sharply denned.

The best situation for finding the bacilli are fresh
nodules which have not yet ulcerated ; in old ulcers, in
pus, in the secretions of the nose, &c., it is often impos-
sible to demonstrate bacilli, possibly because they have
passed into the spore stage. Weichselbaum has sue-

BACILLUS MALLEI. 279

ceeded in demonstrating the bacilli microscopically in the
blood of a patient suffering from glanders, and Philipo-
wicz was able to set up the disease in healthy animals
by injection of the urine of a guinea-pig suffering from
glanders.

For the cultivation of the bacilli fresh nodules are most Cultivation,
suitable; nevertheless, pure cultivations have been obtained
from abscesses. — On slices of boiled potato kept at 35°
C., they form within 2 or 3 days a brownish, slimy, but
not very thick layer. The cultivations can be best pre-
served by inoculating mashed boiled potatoes, kept in
Erlenmeyer's flasks, in the form of a layer on the
bottom 1 to 2 cm. in thickness ; in these circumstances
a chocolate-brown layer is formed on the surface, which,
if protected from drying, contains for months living
bacilli or spores. Potatoes are the best nutrient
medium, and next to them comes solidified blood serum.
On serum kept at 37° C. we see, after three days, small
transparent discrete drops, which scarcely differ in colour
from the surface of the serum, but which distinctly pro-
ject above it. According to Weichselbaum and Kitt the
glanders bacilli also grow at about 25° C., although much
more slowly. On nutrient agar they form drop-like, soft,
greyish- white colonies ; in liquid nutrient jelly a tenacious
whitish mass is developed.

Under the microscope the cultivations show the same
bacilli which we find in the glanders nodules ; as the
result of differences in age and development there are
greater differences in the lengtl >f Uio bacilli ; as a rule
spore formation can be distinctly seen.

If the cultivations were inoculated into house-mice, no Experiments
result followed ; rabbits were partially susceptible, but in on amr
some only local ulcers formed, anu these subsequently
healed up. On the other hand the inoculation was always
successful in the case of field-mice, guinea-pigs, horses,
asses, and also in one sheep. — Field-mice die after
subcutaneous inoculation with small quantities of the
cultivation within 8 days, and show on post-mortem
examination numerous small greyish-yellow nodules
full of bacilli in the spleen and liver. In the case of

280 BACILLI PATHOGENIC IN MAN.

guinea-pigs an ulcer develops 3 or 4 days after inocu-
lation, and this is followed by swelling of the nearest
lymphatic glands. If small quantities are inoculated
the process may remain for weeks in this stage, in other
cases acute nodular swellings form in the testicles,
the ovaries, the vulva, or the feet, and ulcerative pro-
cesses occur in the nasal cavities. In the case of
horses and asses the typical picture of glanders was
obtained . — The most susceptible animals, and hence
the animals best suited for the diagnosis of glanders, are,
according to Molkentin and Griinwald, young dogs.

From these results we can no longer doubt that the bacilli
described above are the true cause of glanders. The obser-
vations made by Bouchard and Capitan, which differ as to
the morphological characters of the causal micro- organisms,
have evidently been due to their defective method of culti-
vation ; for they made their inoculations into fluid nutrient
media from open ulcers, containing of course other bacteria,
and thus they must always have had a great excess of the
more quickly growing saprophytes in their cultivations ; the
majority of these may, as Bouchard describes, have consisted
of cocci, and the few glanders bacilli which were present, and
to which the virulence of the cultures was due, may have been
masked by them.

Bacillus diphtheria.
(Loeffler.)

Difficulties in As to the etiology of diphtheria, more especially of
inve^atiST1 tne epidemic diphtheria of the throat, little that is trust-
of diphtheria, worthy is as yet known, although recently Heubner has-
made out some important facts with regard to the more
intimate process of the origin of the diphtheritic mem-
brane, and with regard to the ultimate part played by
the bacteria in the formation of the membrane. The
difficulties which stand in the way of the knowledge
of the ultimate causes of this disease are evidently
particularly great and manifold. As the result of our
recent investigations the possibility presents itself that
in the case of diphtheria we have to do with organised
infective agents which cannot be rendered visible by our

BACILLUS DIPHTHERLE. 281

present means, and perhaps require entirely new methods

for their recognition. Expert microscopists, such as

Eberth, Weigert, Heuhner, Fiirhringer, Loeffler, have

been unable to find any micro-organisms, either in the

deeper parts of the affected portion of the throat, in

sections of the uvula and tonsils, in the internal organs

in cases where there has been marked general infection

of the body (especially in the kidneys), or in the blood.

When we take into account the great number of negative Negative re-

results, we must conclude that in the few cases in which examination

bacteria have been demonstrated in the kidneys, or in of the internal

organs .
other organs, we have to do with bacteria which have

entered accidentally. — Unless we conclude from these
negative results that we have not as yet been able to
render the infective agents of diphtheria visible, there
remains as a second explanation of the facts, the
assumption that in the case of diphtheria, even in the
cases where the morbid process is spread over parts of
the body far removed from each other, we have only a
local development of the infective micro-organisms in
the diphtheritic membrane, that some soluble noxious
materials are produced in that situation by certain
micro-organisms, and that these products cause the
other symptoms of disease. Even on this assumption,
however, we meet with great difficulties in our attempts
to discover the specific bacteria which furnish these
noxious products. At the primary seat of disease,
and in diphtheritic membranes, there is, it is true, no
want of micro-organisms ; but since we have begun not
to see the cause of the disease in the presence of any
sort of bacteria, but to require that for each well-
characterised disease there must also be specific, well-
characterised infective agents, we have the further task
of discovering which of these various species of bacteria
is of importance etiologically. We know now that a Mixture of
number not only of saprophytic bacteria, but also

organisms which are very pathogenic in certain animals, the diphther-
inhabit the cavity of the mouth of healthy individuals,
and these find a good nutrient soil in the diphtheritic
membrane ; without doubt, also, one of these kinds may

282 BACILLI PATHOGENIC IN MAN.

grow better there than the others, and hence, in all
probability, we shall see one or other species in largest
numbers in the great majority of cases, thus leading us
to the erroneous conclusion that they have a specific
etiological meaning. It is evident that here we can only
attempt to isolate the true infective agent with extreme
caution, and with care that fall weight is attached to
all the sources of error,
insuscepti- Further difficulties arise from the behaviour of the

bility of the , ,. .. IIP . mi

lower animals, animals ordinarily employed for experiments. These
are much less sensitive than man to the infective agents
of diphtheria ; infective experiments with diphtheritic
membrane have been carried out very extensively in
various kinds of animals, but very often without
any corresponding effect, although the membranes were
placed directly on the mucous membrane of the open
trachea (Trendelenburg, Francotte, and others). In
some cases it is true that illness of the animals, for-
mation of false membranes in the trachea, &c., have
been observed, but there has never been a development
of typical diphtheria, with all its various symptoms, and
those 'morbid phenomena which were observed could
also be caused by inoculation with non-diphtheritic
putrefying material (Hueter, Marcuse, and others), and
also with various species of bacteria evidently not in
etiological connection with human diphtheria, but never-
theless occurring at times in the normal secretions of
the mouth. Such morbid conditions in animals re-
sembling diphtheria cannot be of themselves utilised
for the recognition of the infective agent of human
diphtheria, and thus there is increased difficulty in
experiments made for the purpose of clearing up the
etiology of this devastating disease.

Various kinds Finally, many clinical and epidemiological facts indi-
of diphtheria. cate ^^ ^^ are varioug forms Of diphtheria caused

by different infective agents. If this idea is confirmed
it is evident that a further complication of the investiga-
tions is unavoidable.

Former investigators have, without doubt, paid too
little attention to these dangers and difficulties, and the

BACILLUS DIPHTHERIA. 238

repeated supposed discoveries of the diphtheritic bacteria
rested on errors. — Of late Loeffler has attempted to clear J
up the etiology of diphtheria by the employment of
better methods, and by bearing carefully in mind the
sources of error. He found in sections of diphtheritic
membranes that, in addition to what were evidently
accessory organisms, two kinds were present which were
of special interest ; on the one hand, cocci which were Streptococci.
arranged in the form of chains, and chiefly occurred in
the diphtheritic throats in cases of scarlet fever. These
had their starting point usually in a loss of substance of
the diseased mucous membrane, and extended from that
point into the tissue in the form of wedge-like or tongue-
like masses, leaving necrosis of the tissue behind them ;
they penetrate into the lymphatic vessels, and at times
spread through the whole body. That these chains of
cocci play a secondary role in diphtheria is probable
from the fact that in other diseases accompanied by
lesions of mucous membranes we can observe a similar
growth of streptococci ; and further, they were not so
much characteristic of typical cases of diphtheria, with
a definite membrane in the throat and with spread of
the process to the air passages, as of cases of scarlet
fever, in which the process remains limited to the throat.
As to the characters of these cocci on cultivation, and
in experiments on animals, see page 194.

The other bacteria found by Loeffler in the majority Loeffler'*
of the cases of typical diphtheria are rods with peculiar
morphological and biological characteristics; they are
probably identical with the form of bacillus which was
also found by Klebs in diphtheria, and was looked on
by him as the infective agent of the disease, although he
did not succeed in obtaining pure cultivations of the
organisms. Loeffler found these bacilli, which stain
markedly with methylene blue, in the false membranes
at a deeper level than the masses of other bacteria
which covered the surface, namely, at the inner margin
of the layer of exudation ; they also occupied the oldest
portion of the membrane, and penetrated deeper than membrane.
all the other bacteria. Cultivations could not be made

284

BAQILLI PATHOGENIC IN MAN.

on the ordinary gelatine plates, but Loeflfler succeeded
in growing them by diluting a small portion of the
material taken from the diphtheritic membrane, and by
inoculating drops of the diluted material on solidified
blood serum ; in this way pure cultivations of the bacilli
Mode of com- were obtained. Wyssokowitsch recently succeeded in
isolating the same rods from a piece of diphtheritic
membrane which had been coughed up, employing agar
plates for the purpose, and keeping the material at
35° C. In order to render the isolation of the organ-
isms certain one must always employ a large number of
plates, as a large proportion of them are generally com-
pletely overgrown by the rapidly growing saprophytes. —
Loeffler found that the best medium was a solid material
composed of three parts of calves' or sheep's blood
serum, and one part of neutralised veal broth, to which
one per cent, of peptone, one per cent, of grape sugar,
and a half per cent, of common salt were added. On
this soil the bacilli grew at 37° C. in the form of whitish
opaque drops, or of a thick white layer, which attained
the acme of its development within two days. Agar
jelly forms an almost equally favourable soil ; on nutrient
jelly growth also occurs at about 22° C., but it is slow
and imperfect ; no growth appears to take place on
potatoes.

On agar plates the youngest colonies lying in the
substance of the material appear, when magnified 80
diameters, as round or oval, dark
brown, coarsely granular, and not
sharply outlined discs. Several
colonies often run together, so that
irregular figures are formed. The
superficial colonies are greyish-
yellow, with granular, rough,
almost net-like, surfaces, and with
the a delicate wavy border.

The rods are immobile, the

of majority of them are slightly bent. They vary much in
length, being on an average of much the same length as
the tubercle bacilli, but they are considerably thicker than

Fig.
di

81. — Colonies of
iphtheritic bacilli
on agar plates X
80.

Morphological

agar.
b, those situated on
surface.

BACILLUS DIPHTHERIA. 285

the latter. It is not uncommon to find one end, and
often even both, swollen; here and there there are
distinct cluh-like forms. In an un-
stained condition the pole, and often
also other portions of the bacilli,
present a highly refracting appear-
ance. When stained with methylene ™ 7o TV ^v. •*•

J Fig. 82. — Diphtheritic

blue these portions of the rods take bacilli x 1200.
on the stain markedly, and thus there °> ^VSk£a ^h
is not uncommonly an appearance as J> involution forms.
if the bacillus were composed of short pieces with ir-
regular outlines. In the case of some bacilli, more
especially when they are taken from cultivations on
soil which was not very favourable for their growth,
the ends appear very markedly enlarged, or the middle
is distinctly thickened, or the rod is divided into large
roundish or oval bodies. These deviations from the
normal form of the bacilli, the club-like swellings, and
the fragments which arise by fission, evidently imply
the occurrence of involution. In favour of this view we
have the fact that when they are grown on the best
soil — in the living body — these abnormal swellings
seldom appear, and are much less marked, so that there
is only a slight thickening of individual portions, and
more especially of the ends. On the other hand these
appearances are the more numerous the worse the soil,
and the more imperfect and slow the growth. — We
might be inclined to look on the portions of the bacilli
which are highly refracting as spores, or at least as the
commencement of the formation of spores, but Loeffler
was able to show that the rods, even when they showed
large numbers of these bodies, died without exception
after being exposed for half an hour to the temperature
of 60° C. Nor is there any better reason for looking on
these bodies as the early stage of arthrospores at any
rate not till we have some evidence that they possess a
greater resisting power to noxious influences than
bacilli in which this change has not occurred. — At the
temperature of the room .the cultivations retain their
vitality for about three months.

BACILLI PATHOGENIC IN MAN.

Experiments As the result of experiments on animals which were
made with cultivations of Loeffler's bacilli, it was found
that mice and rats were immune against their action ;
guinea-pigs and small hirds died after subcutaneous in-
oculation, with the occurrence of a whitish or hsemorr-
hagic exudation at the seat of inoculation, and extensive
oedema of the subcutaneous cellular tissue. No micro-
organisms were found in the internal organs of these
animals. If the cultivations were applied to the trachea
of rabbits, fowls, and pigeons, characteristic and often
very extensive false membranes appeared. These formed
in like manner on the scarified conjunctiva of rabbits,
and at the entrance of the vagina of guinea-pigs.
Besides the false membranes, there also occurred a
bloody oedema, h£emorrhages into the tissue of the lym-
phatic glands, and effusions into the pleural cavity.
Young animals, as a rule, succumbed to the infection
more readily and more quickly than older ones.

Objections to The symptoms caused by the bacilli are thus very

the etiological . ., , , .

significance of similar to the morbid phenomena which are set up in
l' man by the diphtheritic virus. Nevertheless, Loeffler
has hesitated to assume as a matter of certainty that
these bacilli are the sole specific exciting agents of
diphtheria, because they were not found in the false
membranes in a number of typical cases of diphtheria ;
because they were not present in the false membranes
developed in animals in the same typical arrangement
as was observed in man, but were, on the contrary,
either entirely absent or only present in small numbers ;
and, thirdly, because they could not be inoculated on
the healthy mucous membrane of susceptible animals,
but required the presence of small injuries before they
could cause infection. Nevertheless, it is quite possible
that the bacilli, whose great tendency to involution was
mentioned above, had already died in many of the
membranes, or had been eliminated, and were hence no
longer found ; further, that even in the case of man
trivial injuries of the mucous membrane may be necessary
to enable them to enter, and that thus these objections
do not exclude the possibility that these bacilli play a

BACILLUS DIPHTHERIA. 237

causal part in the disease. — Of greater weight is another
objection which also arises from an observation made by
Loeffler. On examining the secretion of the mouth in
20 children and 10 adults by the aid of cultivation,
Loeffler obtained in one case colonies, which consisted,
as shown by the microscope, by cultivation experiments,
and by experiments on animals, of these diphtheria
bacilli. Nevertheless, it is not impossible that the
pathogenic bacilli may at times be present in the secre-
tions of the mouth without setting up symptoms of
disease, either because there are no points at which it can
enter the body, or because, for some other reason, the
patient is immune, and this assumption hardly seems to
be too unlikely when we remember the characteristic dis-
tribution of these bacilli, and the striking result of the
experiments on animals, which seem distinctly to imply
that at least for a certain group of diphtheritic diseases
these bacilli are the causal agents.

As regards the bacteria of diphtheria in pigeons and
calves see below.

Emmerich has asserted in a preliminary communication Emmerich's
published in the proceedings of the Hygienic Congress, at
Hague, that the exciting agents of diphtheria are short, thick
rods, which are twice as long as broad, and which grow
luxuriantly on nutrient jelly in the form of round, whitish
colonies, about the size of the head of a pin, and on potatoes
in the form of a thick, whitish-yellow layer. The cultivations
were successfully inoculated on pigeons, rabbits, and white
mice ; if a cultivation was applied to the mucous membrane
of the trachea of a rabbit, it was found after death, which
occurred about 60 hours later, that the mucous membrane
was covered with a croupous, dirty greyish-yellow membrane ;
further, there was fibrinous inflammation of the pericardium
and fibrinous deposits on the lungs. The bacilli were not
only found in the false membrane and the mucous membrane,
but were more or less numerous in the blood and internal
organs, in the liver and spleen, and more especially in the
kidney. Emmerich obtained the same result from 8 cases
of human diphtheria, and 6 cases of pigeon diphtheria, and
ho looks on human and pigeon diphtheria as diseases caused
by the same infective agent.

Emmerich's conclusions are, however, by no means suffi-
ciently satisfactory. According to the best observations, we

288 BACILLI PATHOGENIC IN MAN.

cannot accept the identity of pigeon diphtheria with human
diphtheria ; the almost constant presence of numerous bacilli
in the internal organs, and more especially in the kidneys of
the animals experimented on, when contrasted with the nega-
tive results obtained in man, seem to show that the disease
caused by Emmerich's bacilli differs in an important manner
from human diphtheria ; as to the distribution of his bacilli
in sections of human diphtheritic membrane, Emmerich
makes no statements, although it must surprise the reader
that Emmerich has obtained such markedly contradictory
results to those obtained by Loeffler in his careful investi-
gation, and that he has assigned to other bacteria which were
not at all thought of importance by Loeffler, a greater
role than Loeffler's streptococci and bacilli. — It is possible
that the method employed by Emmerich, which is one by no
means to be recommended, led to erroneous conclusions.
Emmerich introduced pieces of mucous membrane and par-
ticles of the false membrane into nutrient substrata, allowed
impure cultivations to grow, and then at once inoculated
these on animals, with the view of separating the pathogenic
from the non-pathogenic bacteria. By this mode of procedure
it was almost unavoidable that septic bacteria which are
almost always present in the secretions of the mouth, and in
diphtheritic membranes, should infect the animals, and thus
obscure the true diphtheritic bacteria.

The following bacilli, which are pathogenic on man,
are only imperfectly known, and require further investi-
gation : —

Sypliilis.

Lustgrarten's During the course of the last few years numerous
Sacilli? authors (Hallier, Lostorfer, Klehs, Aufrecht, Birch-

Hirschfeld, and others) have made statements which are
evidently erroneous as to the discovery of the infective
agents of syphilis, but lately Lustgarten has succeeded in
demonstrating micro-organisms in the syphilitic new for-
mations, by the aid of a special method of staining. These
organisms may with considerable probability be looked
on as the specific infective agents of syphilis, on account
of their characteristic behaviour with regard to staining
solutions, on account of their constant presence, and on

SYPHILIS. 289

account of the mode in which they are arranged in the
diseased tissues.

The method of staining successfully employed by Lust-
garten consists in staining the sections in aniline gentian
violet solution, and subsequent decolourisation by means
of a solution of permanganate of potash, the dioxyde of
manganese — the product of the reduction process — being
subsequently removed from the sections by sulphurous
acid ; after this treatment the sections appear quite
colourless, with the sole exception of the syphilis bacilli.

Lustgarten's method may be shortly described as Method of
follows:-

The sections remain in a mixture of 100 parts of aniline
water, and 11 parts of concentrated alcoholic gentian violet
solution for 12 to 24 hours at the ordinary temperature,
or for 2 hours at the body temperature; they are then
washed in alcohol, then for about 10 seconds in a 7-| per cent,
watery solution of permanganate of potash ; in that fluid the
preparations become covered with brownish flakes of dioxyde
of manganese. By placing them for a short time in a watery
solution of sulphurous acid, the dioxyde of manganese is
reduced, dissolved, and washed away ; the sections are then
washed in distilled water, and if they have not been suffi-
ciently decolourised, the process is repeated; as a rule it is
only after repeating it three or four times that a good result is
obtained. Finally the section is dehydrated in alcohol, and
then placed in the usual manner in oil of cloves and Canada
balsam. Cover glass preparations are treated in like manner,
with the exception that, after the action of the violet, water,
and not alcohol, is employed as the first decolourising agent.
Not only is the tissue decolourised by this plan, but also all
bacteria, with the exception of the syphilis bacilli, and the
bacilli of leprosy and tubercle ; the syphilis bacilli may, how-
ever, be distinguished from the latter by the fact that they
are quickly decolourised by treatment with hydrochloric acid
or nitric acid.

The bacilli found in syphilitic new formations are Morphological
usually bent, slightly S-shaped, and on an average 4J cliaracters-
p. long ; they often show a slight knob-like swelling at
the ends ; their contour is not quite uniform, but it is
more or less wavy, or indented at parts. When highly
magnified we can see, in the dark blue stained bacillus,
clear oval refracting spots two to four in number and

19

290

BACILLI PATHOGENIC IN MAN.

placed at equal distances ; these spots are, in all proba-
bility, spores.

The bacilli do not occur free in the tissue, but are for

the most part present

only in large oval or

polygonal cells, in the
interior of whi<* they

two to eight, often
crossed or twisted
round one another. As
a rule there are only
relatively few bacilli in
the affected parts, so
Fig. 83A.— Syphilis bacilli. Group from that at times several

a chancre X 1050. (After Lustgarten.) .. . ,

sections must be ex-
amined before a cell containing bacilli is found.

Lustgarten has been able to demonstrate these bacilli
in each of 16 cases of syphilis examined by him. They
were also found in a periosteal gumma in a case of
congenital syphilis ; on the other hand, they were absent
in two cases of soft chancre, and in numerous specimens
of normal and pathological organs which were examined
for purposes of control,
other methods De Giacomi, in demonstrating these bacilli, has

of staining.

^^^•iQ:^^!^

Fig. 83s. — Wandering cells con-
taining syphilis bacilli X 1050.
(After Lustgarten.)

Fig. 83c. — Cover glass preparation
from the pus from a chancre
showing syphilis bacilli X 1050.
(After Lustgarten.)

employed a solution of chloride of iron to decolourise
the sections and cover glass preparations ; this method
has been tested and recommended by Gottstein. In

RHINOSCLEROMA. 291

this method the sections are stained for 24 hours in
fuchsine, washed in water, then placed for a few seconds
in pure or diluted solution of chloride of iron, washed in
alcohol, and then transferred to oil of cloves. The
syphilis bacilli remain red or reddish-violet, the tissue
and the other bacteria — with the exception of tubercle
bacilli— remain unstained. Double staining can also be
employed, both after this method and after Lustgarten's
plan, but it does not add much to the distinctness of the
picture.

Doutrelepont and Schiitz were able to demonstrate
Lustgarten's bacilli by placing thin sections for 24 to
48 hours in a 1 per cent, watery solution of gentian
violet, then for a few seconds in dilute nitric acid (1 to
35), and then for about ten minutes in 69 per cent,
alcohol ; the tissues were afterwards stained in a dilute
watery solution of safranin. After this treatment the
tissues and nuclei had a bright-red appearance, while the
syphilis bacilli were blue.

An investigation which has been recently made for Similar bacilli
purposes of control by Alvarez and Tavel in Cornil's mt
laboratory, throws doubt on the exclusive applicability of
Lustgarten's method of staining to the syphilis bacilli.
These authors found bacilli in the smegma of the prepuce
and of the vulva, which presented the same characters,
as regards staining, reaction, and morphological appear-
ance, as Lustgarten's bacilli. Hence further investi-
gations are required to demonstrate the causal connection
of these bacilli with syphilis, although their distribution
in the tissues is decidedly against the idea that they are-?
only accidental.

RldnosclerGina.

In this disease, which has been observed in Austria, Bacilli of
Italy, and Central America, and which is characterised
by thickening of the skin and mucous membrane of the
region of the nose and the formation of nodules, charac-
teristic micro-organisms were first described by Frisch,

292 BACILLI PATHOGENIC IN MAN.

and later by Pellizari, Chiari, Alvarez, and Cornil.*
On examining sections of the affected skin we find a
small celled infiltration of the cutis, sclerosis of tho
small .vessels, and a considerable number of large
spherical cells, most of them containing several small
nuclei ; the protoplasm of these cells contains very large
numbers of bacilli, which are also present in the
surrounding tissue and in the lymphatic vessels. The
bacilli are short rods, 1'5 to 8 /*, in length, and *5 to "8
p. in breadth ; their ends are rounded, and in their
interior are three or more markedly stained granules.
In order to render the bacilli visible, the sections are
best stained in methyl violet for 24 or 48 hours, and
then placed in iodine water. If we employ a strong
violet solution, and leave the specimens in it for 48
hours, and then decolourise for 48 hours in absolute
alcohol, we often see that each bacillus is surrounded
by an oval resistant capsule of a light bluish violet
colour. Cultivations, and attempts at inoculation with
these bacilli, have been, as yet, without result. For
further details, see Cornil and Babes "Les bacteries."

Malaria.
(Fievre intermittente, Paludisme.)

For a long time it has been supposed that malaria is
caused by an organised virus, and that it might be possible
to obtain this virus by cultivation on artificial substrata.
From the mode of spread of malaria it is evident that
this disease is not contagious in the ordinary sense, and
does not require the presence of a person suffering from
the disease for direct or indirect transmission ; on the
contrary, it seems to be chiefly connected with a certain
constitution of the local surroundings of man, and is not
dangerous to man in other places. Hence we may
assume that, in the case of malaria, we have not to
do with a true parasite, which can only develop with
difficulty, or not at all, outside the human body, but

* Frisch, Wien. medic. Wochenschr., 1882. — Pellizari, 11 Rhinosckromn,
Florenz, 1883.- Chiari, Wien. medic. Jahrb., 1882, ?ee p. 26.

MALARIA. 293

with an organism which can live, and probably also influence of
multiply under certain conditions, on the dead nutritive
substrata in our ordinary surroundings, and which only
at times takes on a temporary parasitic existence.

As to the substratum which is necessary for the insufficient
development of the virus of malaria, we have as yet the°h>caigpre-
very few facts which are trustworthy or of use in disposition,
connection with artificial cultivation experiments. As
a rule in former times it was thought that a warm, very
moist, or marshy soil, containing a large amount of
organic, and more especially vegetable materials, was a
source of permanent danger in any particular region.
As the result of the careful investigations of Tommasi-
Crudeli, made within the last few years, which have
shown that endemics of malaria may occur also in high-
lying and by no means marshy districts, and also in
regions which have been rendered dryer by planting
eucalyptus trees, it is evident that the amount of
moisture of the soil which is necessary for the deve-
lopment of malaria is very much less than was
formerly supposed ; the other factors of importance have
been so difficult to define more precisely that we evi-
dently require further elaborate investigations in this
direction.

On the other hand, attempts at isolating and cultivating inocuiabiiity
the virus of malaria are the more encouraging because, of malari
as the result of recent experiments, the possibility of
the existence of a true miasmatic virus has been dis-
tinctly disproved ; because, therefore, we do not have to
do with an unorganised something not capable of multi-
plication but produced by a particular soil. Cuboni,
Marchiafava, Dochmann, and quite recently Gerhardt;
have demonstrated that malaria is inoculable from man
to man. Gerhardt was able to set up a distinct quotidian
ague with temperatures up to 41 '1° C. in two healthy
men who had been under observation for a long time,
and in a locality quite free from malaria, by inoculating
them with blood taken during the attack from patients
suffering from malaria.

As the result of the assumption, justified by these

294 BACILLI PATHOGENIC IN MAN.

Attempts to observations, that malaria is caused by an organised

recognise and . , . f . . . . i i T •

isolate the virus, capable of multiplying on dead nutrient substrata,
malaria numerous bacteriological investigations have been set

on foot, the majority of which, however, have been too
Klebs' bacilli, much influenced by preconceived ideas. Thus Klebs and
Tommasi-Crudeli found bacilli in the marshy ground in a
malarial region, and described these organisms as "ma-
laria bacilli "; " rods 2 to 7 M. in length, which grow and
form convoluted threads; these either become segmented
by the appearance of clear intervals in their protoplasm,
more seldom by distinct divisions, and then ultimately
form, when exposed to the air, bundles of threads com-
posed of short segments, or they develop resting spores
in their interior either before or only after fission has
commenced. In the rods these spores appear either
at the centre, or at one end, or they may be both central
and terminal." These bacilli were cultivated in isinglass
jelly, in solutions of egg-albumen, in urine, &c. ; they
only grew in the presence of the air, and when they were
inoculated on rabbits they set up a febrile affection which
Klebs looked on as malaria. The statement with regard
to their morphological characters, the results of the
cultivations and the characters of the disease produced
in animals do not, however, furnish any sort of guarantee
that Klebs was dealing with pure cultivations of specific
bacilli, and not with other infective organisms of the
Bacilli in the soil. Shortly after this communication as to malaria
patients suf- bacilli, Cuboni and Marchiafava announced that they had

maiafifr°m found in tlie blood of Patients suffering from malaria,
and at the period of commencement of the fever, mobile,
short bacilli, usually containing spores at each end, and
on the whole corresponding with the bacilli obtained by
Klebs from the soil. Cuboni and Marchiafava, however,
also demonstrated the same bacilli in the blood of persons
not suffering from malaria, although in smaller numbers.
Then followed observations by Ziehl, who found bacilli
in the blood of three patients suffering from malaria,
the organisms being hammer- shaped, 4 /*. in length,
and '7 /*. in breadth, and with spontaneous movement ;
the author looked on these as identical with the reds

MALARIA. 295

described by Klebs ; he found them both during the
paroxysms, and also in the afebrile period. Ziehl
examined the blood of 25 patients suffering from other
diseases without finding these bacilli ; they were, how-
ever, obtained in the case of a patient suffering from
diabetes.

About the same time Laveran stated that he had Laveran's
found in the blood of patients suffering from malaria, of tbeTlood.
micro-organisms of a totally different appearance. Ac-
cording to him these organisms belong to the class of
protozoa, and in the fully developed state they form
transparent spheres of the size of red blood corpuscles,
and shoot out fine mobile filaments ; dark red pigment
granules, in active movement, are enclosed in the
interior of the spheres. Richard has confirmed these
observations, which, howrever, were made without the
aid of the microscopical means now employed.

Finally, in the year 1883, Marchiafava and Celli MarchiafavaV
observed in the blood of malarial patients, taken during examination
the period of fever, dried in a thin layer on the cover of blood,
glass, and then stained with methylene blue, peculiar
alterations of the red blood discs. Bluish stained bodies
of various size and form were present in a greater or
less number of the blood corpuscles; at first these
bodies resemble micrococci stained of an intense blue
colour, and in addition to these there are larger round
or oval bodies, in the interior of which are granules, or
masses of black pigment. At times the whole blood
corpuscle is converted into a faintly blue stained round
mass, which is filled with small clumps of pigment.
On examining the fresh blood, without any addition to
it, the larger bodies appear as colourless patches in the
red blood discs ; these patches usually contain pigment
granules, and gradually increase in size, till ultimately
the whole red blood corpuscle is composed of a colour-
less substance enclosing a large number of pigment
granules.

Yon Sehlen confirmed these observations, finding in
blood taken from malariul patients during the febrile
stage, and prepared with all ordinary precautions,

296

BACILLI PATHOGENIC IN MAN.

Criticism of

have been
the present

round granules staining with methylene blue, *5 to 1 p.
in size, partly enclosed in the red blood corpuscles,
partly lying free between them ; in addition to these
granules, there were ring-shaped bodies of almost
double the size. When this blood was inoculated on
nutrient agar, he obtained a pure cultivation of a
species of micrococcus, growing in the form of a white
gelatinous mass ; in addition, in one case he obtained
yellowish growths of micrococci. No positive results
were obtained by experiments on animals with either of
these species ; these experiments have, however, only
as yet been made on rats, and are not concluded. The
method employed by Von Sehlen for making the cultiva-
tions affords no guarantee of the exclusion of accidental
micro-organisms. Examinations of soil and air made
by Yon Sehlen in malarial regions and in regions free
from malaria led, in both cases, chiefly to the isolation
of two species of bacilli and cocci, the latter of which
grew in a similar manner to those cultivated from blood.
and were likewise without any marked action on the
animals experimented on.

A consideration of these various facts leads us to fie
conclusion that the cultivation experiments have not as
vet yielded any trustworthy results as to the organisms
which take part in the malarial infection. The obser-
vations as to the presence of large bacilli in the blood
of patients suffering from malaria are undoubtedly
erroneous, as shown by the control investigations which
have been subsequently made. We cannot at once say
the same as regards the results obtained by Laverau,
by Marchiafava and Celli, and by Yon Sehlen, which
agree with regard to the constant occurrence of peculiar
bodies in the interior of the red blood corpuscles ; we
can only say that Laveran evidently obtained a number
of forms, as the result of errors in preparation, and mis-
took these forms, as well as the altered blood corpuscles,
for stages of the development of a micro-organism. As
the result of the investigations made by Marchiafava and
Celli, the alteration of the red corpuscles seems to be,
to some extent, a constant occurrence in malaria ; it is,

MALARIA. 2C7

however, as yet doubtful whether the granules and
bodies observed are to' be looked on as parasitic forms,
or only as secondary products of the breaking up of
blood corpuscles arising under the influence of micro-
organisms as yet unknown.

This last assumption, which is nevertheless equally
justified, would open up the prospect that .we must
search for the true infective agents of malaria with other
technical means than have as yet been tried ; and it is
probably advantageous to remember that these agents
may not necessarily belong to the class of fission fungi,
but to some other class of micro-organisms.

In the case of yellow fever Babes demonstrated in two
cases short rods, similar to the typhoid bacilli, with
large spores, usually at one end, and present in the
mucous membrane of the small intestine. As regards
the presence of cocci in this disease, see page 203.

In the case of whooping cough, Letzerich (Yirchow's
Archiv, 1874) looks on the infective agents as cocci,
and Burger (Berl. klin. Woch., 1883) as short rods
often constricted in the middle, and present in the
sputum of the patient ; nevertheless there is no sufficient
support for either of these views.

In some cases of lichen ruber, Lassar observed, on
staining with fuchsine, the tissue at the same time
being stained brown, distinct and extremely fine bacilli,
which are aggregated in thick masses, and can only be
recognised as individual rods under very high powers.
They lie chiefly in the lymphatic channels of the aifected
parts in the form of tube-like masses.

In the case of xerosis conjunctives, Leber, Kuschbert
and Neisser, and Schleich found micro-organisms.
Leber describes them as short rods, often resembling
cocci, which grow readily on nutrient gelatine, and
when inoculated in large numbers on the conjunctiva of
rabbits (the eyes of the animals being kept closed for
forty-eight hours by means of superficial sutures) led to

293 BACILLI PATHOGENIC IN MAN.

necrosis of the epithelium of the cornea, and to suppura-
tive inflammation of the cornea. According to Kusch-
bert and Neisser, the bacilli are about as long as thoso
of mouse septicaemia, and are of varying breadth, accord-
ing as the sheath which surrounds the bacillus like a
capsule is stained or unstained. If a small portion of
the deposit on the surface of the conjunctiva is stroked
over the surface of blood serum jelly, dry, fatty whitish
streaks grow, at the temperature of 87° C., these streaks
consisting of bacilli similar to those found on the con-
junctiva. Neisser observed the production of spores,
forming small spherical swellings at each end of the
bacillus. At times the terminal joints break up into
broad plates, or become swollen like a pear (formation
of involution forms). Experiments on animals with the
cultivations gave entirely negative results. As, how-
ever, the methods of cultivation employed were not
devised with sufficient care to exclude accidental bacteria,
which were so apt to be present on account of the exposed
seat of the disease, the question as to the significance
of the bacteria, which have as yet been found, for the
etiology of xerosis cannot be regarded as completely
settled.

In the case of canes of the teeth, which is probably
due to the action of one or several species of specific
bacteria, different bacilli have been isolated, which, how-
ever, seem chiefly to play a saprophytic part, and at the
most to prepare the tooth for the occurrence of caries.
As regards these organisms, see below.

As regards leptothrix and other bacteria of the mouth,
see later. As regards jeqnirity, see the following
chapter.

BACILLUS OF RAUSCHBRAND. 299

B. BACILLI PATHOGENIC IN ANIMALS.

The following bacilli have been recognised as the
exciting agents of infective diseases, partly in the case
of domestic animals, and partly in animals used for
experiments : —

Bacillus of Rauschbrand.
(Bacterie du Charbon symptomatique.)

In the case of Kauschbrand of cattle, Bellinger and
Feser, and later Arloing, Cornevin, and Thomas, have
found large rods, resembling anthrax bacilli, but never-
theless distinctly different, and have come to the con-
clusion that they are the exciting agents of the disease.
This disease, which chiefly attacks young cattle, a half Symptoms of
to four years old, and lambs, and which often runs R
through herds in the form of very fatal endemics, begins
with loss of appetite, followed chiefly by the formation
of an irregular swelling in the skin at some part
or other of the body; this swelling rapidly increases
in size, and distinct crepitation can be felt at its centre.
Death occurs 36 to 48 hours after the commencement
of the symptoms, the temperature rising at first and
th6n sinking to an abnormal degree. On making a Post-mortem
post-mortem examination we find, at the seat of the ai
swelling in the subcutaneous cellular tissue a collection
of gas, which chiefly consists of a mixture of cabornic
acid and methane ; the muscles and cellular tissue are
soaked with a large quantity of sero-sanguineous fluid,
and the surface of the muscles are of a black colour ;
the tymphatic glands in the neighbourhood of the part
affected are markedly hyperaemic. In the internal
organs there are no characteristic or constant alter-
ations. In the serous fluid between the fibrilla? of the
muscle, and in the subcutaneous cellular tissue there are
large numbers of bacilli ; these may also be found in
cover glass preparations made from the liver and spleen,
and in the blood vessels and capillaries, though this is
rare, and they are only found in these situations in

300 BACILLI PATHOGENIC IN ANIMALS.

considerable numbers when the post-mortem examination
is not made immediately after death. Inoculation
with the organs or the serous fluid from the tumours
causes the same or similar phenomena and a fatal
result, in calves, sheep, goats, rabbits, and guinea-
pigs ; horses, asses, and white rats are but little
<\ susceptible; swine, dogs, cats, ordinary
\ f ra^s, and fowls are completely immune.
& ^ In the case of guinea-pigs, the sub-
Fig. 84.— Eausch- cutaneous injection of the serous fluid
asporebbearinat causes an extensive cedema of the sub-
cutaneous tissue ; the animal dies after
two or three days, and then it is found that the sub-
cutaneous tissue is infiltrated with a large amount of
sero- sanguineous fluid, and that the muscles are
discoloured. If too small a quantity is injected, only a
local tumour is formed in the animal inoculated, and
this tumour heals and leaves the animal immune against
larger doses.

Morphological The bacilli are 3 to 5 /i. in length, *5 to "6 /x. in
the^bacilli. ° breadth, with distinct spontaneous movement, and thus
at once distinguished from the anthrax bacilli. They
often show at one end a round swelling, so that their
form resembles that of the clapper of a bell, and in this
swelling an oval refracting spore, exceeding the rod in
diameter, is gradually formed.

Cultivations. Arloing, Cornevin, and Thomas were able to cultivate
the bacilli, but only by the exclusion of oxygen. The
organisms grow best in fowl-broth, to which a little
glycerine and sulphate of iron have been added, the
vessels employed being exhausted of air, or filled with
carbonic acid. In cultivations in other nutrient media
the virulence of the organisms diminishes very rapidly.
Artificial The same observers were also able to obtain an artificial

theerausch^ °f attenuation of the rauschbrand bacilli by another method,
brand bacilli, and on inoculation of these attenuated bacilli they were
inoculation/ able to produce immunity of the animals against the
virulent bacilli. They found in the first place that local
affections, which left immunity behind, arose after sub-
cutaneous inoculation of small quantities of the serous

BACILLUS OF EAUSCHBRAXD. 301

ceclematous fluid containing the bacilli ; that immunity,
however, was obtained with still greater certainty when
small quantities of the oedematous fluid (in the case of
cattle, 3 to 5 drops) were injected into the veins, with
such precautions that none of the material passed into
the subcutaneous tissue. At a later period another
method proved to be more trustworthy and more prac-
ticable : the virulent odematous fluid was dried quickly
at 32° to 35° C. ; the dried mass was rubbed up with
water and heated to 100° C., and this formed the first
vaccine material; another portion heated to 85° C.
formed the second vaccine. The dry vaccine, which can
be sent where required, is rubbed up before use with
100 parts of water, filtered, and injected to the amount
of 1 c.c. m. into the animals ; the second vaccine, which is
less attenuated, is injected from 9 to 14 days later than
the first. The inoculation is made in the case of cattle
at the tail, and in the case of sheep on the inner surface
of the thigh. The animals so inoculated ought to be
completely immune against artificial and natural infection
with virulent rauschbrand bacilli. The accuracy of these
statements has been confirmed by numerous experiments,
and it is probable that the protective inoculation against
rauschbrand may be practically and advantageously em-
ployed. Thus Strebel states that in the course of 1884,
in 7 cantons in Switzerland 2,200 cattle were vaccinated,
of which only a few developed a local tumour, from which
they recovered, and of which a much smaller percentage
died of rauschbrand acquired in the natural manner than
was the case with uninoculated cattle kept under the
same conditions. The experiments which have been
made with other protective inoculations seem, however,
to indicate that we must maintain a certain reserve with
regard to the first favourable reports of the results of
rauschbraud inoculations.

Rauschbrand and the bacilli which cause it show great Differences
resemblance with malignant oedema and its cause, bacm
However, the oedema bacilli, as a rule, form longer tho,s.e of
threads, while the rauschbrand bacilli are always in the oedema.
form of isolated short rods ; further, from the endemic

802 BACILLI PATHOGENIC IN ANIMALS.

and epidemic occurrence of rauschbrand we must assume
that the distribution of the infective agents is different
to that of the oedema bacilli, which occur everywhere in
our surroundings, Kitt has also observed that while
rauschbrand is always fatal after inoculation, a calf
inoculated with malignant oedema became very ill, but
recovered. It is probable that cultivations on solid
nutrient substrata may show marked differences between
the two organisms ; but as yet we know nothing trust-
worthy with regard to the mode of growth of the colonies
of the rauschbrand bacilli.

ISTeelsen and Ehlers found that the rauschbrand organisms
formed in the animal body only bacilli and spores, but that, on
the other hand, on cultivation on blood serum cocci developed.
They stated also that on other nutrient substrata the culti-
vation of the bacilli taken from the affected animal did not
in the first place succeed, but that after they had become
accustomed to life outside the body by cultivation 011 blood
serum they then grew on nutrient jelly, &c. These state-
ments, which are opposed to the results obtained by all other
authors, and which are quite unlikely, are probably due to
errors in the methods employed.

Bacilli of swine erysipelas.
(Eouget du pore, Mai rouge, Hog cholera, Pig typhoid.)

Within the last few years various investigators have
.directed their attention to the erysipelas which occurs
epidemically among swine, and which leads to great loss
of life; and as the result of the investigations of Thuillier,
Pasteur, Loeffler, Schiitz, Lydtin, and Schottelius, the
exciting agent of this disease has been discovered in the
animals affected ; it has been cultivated on artificial
nutrient substrata, and the original disease has been
again produced by inoculation of the cultivations on
animals, and thus the chain of evidence necessary to
demonstrate the etiological significance of the infective
agents has been completed.

Symptoms of The symptoms of swine erysipelas as a rule commence
very suddenly. The swine attacked become suddenly
dull, they creep about, and cease to eat ; the voice

BACILLI OF SWINE ERYSIPELAS. 303

becomes hoarse, and there is often evacuation of blood
and slimy fceces. The temperature (which in normal
young swine is between 39° and 39'5° C.) rises at times
as high as 43° C. Sometimes, even in the commence-
ment, but usually not till the height of the disease, red
patches appear at the lower surface of the belly, breast,
and neck, which gradually extend and run together and
ultimately assume a dark red or brown colour ; swelling
of the reddened portions of skin is not noticed, nor does
there seem to be pain, nor is the temperature of the
part apparently above that of the surrounding skin.
Death occurs with increase of the listlessness, at times
with paralytic symptoms of the hinder extremities, at
times with convulsions. The duration of the disease,
from its first appearance until death, varies from a few
hours to four days. Where it ends in recovery, 6 to 20
days pass before the animal is quite well. Fifty- five to
sixty-six per cent, of the animals attacked die ; of those
which survive the acute attack a considerable number
ultimately die of chronic wasting. Older animals are never
attacked, those which are affected are aged from three
months up to at most three years. Different races show
great differences in their susceptibility; the ordinary swine
are almost without exception insusceptible, while the
more noble races — more especially the English Suffolk
swine — show a very great susceptibility to the disease.

According to the observations of veterinary surgeons Mode of
the infection occurs almost entirely from the digestive infec
track, the faeces of the diseased animal getting into the
fodder, or infected mice being eaten. At Lydtin's
suggestion it was on several occasions shown ex-
perimentally, during the inquiry as to the causes and
the mode of protection from swine erysipelas, in the
Duchy of Baden in April, 1885, that swine can be
infected by eating the intestines of other animals which
have died of swine erysipelas. In some of the experi-
ments which gave negative results, the above mentioned
insusceptibility of certain races seems to have come into
play. In some cases also infection was caused by sub-
cutaneous injection. According to the most trustworthy

304 BACILLI PATHOGENIC IN ANIMALS.

veterinary reports, the disease never recurs a second
time.

Post-mortem On making a post-mortem examination of the swine
that die, the skin at the reddened parts is found to be
infiltrated with oedematous and bloody fluid ; the
muscular tissue is soft, and of a greasy pale red
appearance ; the lymphatic glands, especially the glands
of the mesentery, are swollen, of a dark-red colour,
and show on the cut surface punctifonn haemorrhages.
The peritoneum is of a dirty-red colour, or covered
with ecchymoses ; the same is the case with the serous
membrane of the small intestine. The mucous mem-
brane of the small intestine is much reddened and
swollen, and the summits of the folds are deprived of
their epithelium and covered with blood ; the solitary
follicles and Peyer's patches are very prominent, and
here and there, especially in the neighbourhood of
the ileo-caecal valve, their place is taken by ulcers of
considerable size. Liver and spleen are moderately
enlarged. The lungs contain air and a large amount
of blood. There are small hemorrhages in the serous
layers of the pericardium, and constantly in the epicar-
dium of the auricles of the heart.

Morphological In cover glass preparations of fresh blood, and also in
°f ^e Juice of Yari°us organs, in the lymphatic glands, and
in the muscles, we find large numbers of delicate bacilli.
These resemble most closely the bacilli of Koch's
mouse septicaemia, but they are somewhat larger and

thicker ('6 to 1'8/i. in length),
and they also resemble the
latter in that they lie partly
between the blood corpuscles,
either singly or in pairs or
groups of four, and partly in
the swollen white corpuscles,
leading evidently to dege-

Fig. 85.— Pigeon blood containing

the bacilli of swine erysipelas neration of these cells. The

X 600. (After Shuts.) bacim gtain weU with the

ordinary colouring materials ; they also retain their
colour on treatment by Gram's method. In sections the

BACILLI OF SWINE ERYSIPELAS. 805

bacilli are found in largest numbers in the capillaries,
especially of the spleen and kidneys ; the walls of the
capillaries are for the most part thickly covered with
bacilli, while the lumen remains more or less free. The
most beautiful preparations are obtained by means of
Gram's method, or by double staining, in the first place
with gentian violet, which colours the bacilli violet, and
afterwards with picrocarmine, which gives the tissue a
rosy-red hue.

These bacilli grow readily in alkaline meat juice, in Cultivations,
blood serum, and in the ordinary nutrient jelly between
18° and 40° C. ; their growth is extremely like that of
the bacilli of mouse septicaBmia. On plate cultivations
small round patches appear after two or three days,
which have a cloud-like character, and are of a bluish-
grey colour ; these patches gradually increase in size,
and under a low power of the microscope present the
appearance of finely branching bundles of threads, not
at all unlike the lacunas and canaliculi of bone. The
surface of the gelatine remains smooth, and the growth
of the colonies only occurs in the deeper layers. A
puncture cultivation in jelly shows, after three or four
days, bluish- grey cloudy bundles, projecting into the
gelatine on all sides at right angles to the line of
inoculation, so that the cultivation resembles a glass-
brush, such as is usually employed for cleaning test
tubes. This cloudy appearance remains more or less
limited to the neighbourhood of the line of inoculation,
and is not so delicate as in the cultivations of the
bacilli of mouse septicaemia. Growth does not occur
on the surface. In meat infusion these organisms
cause slight opacity of the fluid, and, at a later period,
u whitish-grey deposit at the bottom of the vessel, which
on very slight movement of the vessel rises in the form
of very fine clouds. There is never any scum formed at
the surface.

In the cultivations the bacilli occur singly or united Mobility cf
together in threads of various lengths. According to *
Schottelius the shorter bacilli show distinct, although
not very active, spontaneous movement ; other observers

20

306

BACILLI PATHOGENIC IN ANIMALS.

Spore forma- have, however, failed to observe any movement. In
cultivations in meat infusion which have stood for three
days at the temperature of the room, or for 24 hours at
40° C., we can observe the formation
of small spheres which probably repre-
sent spores, although, on account of
the minute size of the object, no accurate
observations have as yet been made as
to the formation and sprouting of these
bodies. In old cultivations the ordinary
involution forms, such as club-shaped
swellings of the threads, drum-stick
forms, &c., appear.

These cultivations, after being carried
for a series of generations through
gelatine or meat in-
fusion kill with great
certainty the ordinary
house mice in the
course of two to four
days, and on examin-
ation numerous fine
bacilli are found in the

Inoculation on
unimals.

Fig. 86A.— Cultivation of the bacilli of
swine erysipelas in gelatine.
«, puncture cultivation.
b, colony on a plate X 80.

Pasteur's
protective
inoculation .

blood and in the capil-
laries of all the organs. Pigeons are very susceptible,
and die within three or four days. Rabbits are less sus-
ceptible ; after inoculation on the ear of a rabbit an
crysipelatous inflammation occurs in the first instance,
just as after inoculation with the bacilli of mouse sep-
ticaemia. As a rule general infection follows and causes
death in five to six days, nevertheless not uncommonly
complete recovery takes place. Sheep, and perhaps also
young cattle, are susceptible; on the other hand guincu-
pigs and fowls are completely immune. The cultiva-
tions have also been repeatedly inoculated with success
on swine belonging to susceptible races, and at a sus-
ceptible age.

Swine erysipelas has quite recently excited special
interest because Pasteur has recommended a special
mode of protective inoculation which has been experi-

BACILLI OF SWINE ERYSIPELAS. 307

mentally tested in a large number of animals by Lydtin
during April, 1885, in the Duchy of Baden.

Pasteur found that the virus of this disease was more
virulent for swine when it had passed through the
bodies of several pigeons in succession, and had attained
the maximum of its virulence in the case of pigeons ;
that, on the other hand, the danger of the virus as
regards swine was markedly diminished when it was
inoculated through a series of rabbits. If Pasteur in-
oculated the erysipelas bacilli into the thoracic muscle
of a pigeon, the latter died in from six to eight days,
having previously exhibited the external symptoms of
chicken cholera. If, now, the blood of the first pigeon was
inoculated into a second, the blood of the second into a
third, and so on, the latter animals died much more
quickly than the first, and the blood of the last pigeon
was much more virulent for the swine than was the
most poisonous product from a swine which had died
of spontaneous erysipelas. On the other hand, by re-
inoculation from rabbit to rabbit, an increase of the
virulence of the virus in these animals was observed, and
ultimately the animals died without exception, and more
quickly than after the first inoculation. If now Pasteur
inoculated the bacilli thus acclimatised in rabbits on
swine the latter became ill, but did not die, and were
protected, after recovery, against the most virulent
erysipelas poison. (Pasteur always speaks in his papers
of a round microbe, which, when taken from the blood
of rabbits, was larger than in swine, and which had the
form of the figure 8.)

Acting on these principles Pasteur has prepared two Control
vaccines with which young swine — the age is from
8 to 11 weeks — are inoculated by subcutaneous injection vaccine
on the inner surface of the thigh at an interval of
twelve days. By this means an immunity is obtained
which lasts about a year— in other words, is sufficient
to enable the animal to pass through the period of
life when it is most liable to the erysipelas infection.
These vaccines have been recently examined bacterio-
logically by Schiitz and Schottelius, and their action on

308

BACILLI PATHOGENIC IN ANIMALS.

Practical
value of the
protective
inoculation.

animals has also been tested. Besides some indifferent
bacteria mixed with them, both authors found chiefly
the characteristic erysipelas bacilli, and they were able
to convince themselves by experiments that these organ-
isms were as a matter of fact attenuated as regards the
virulence of their action on swine ; in like manner they
were able to ascertain that the pigs inoculated with
these vaccines, and which, after being ill, had again
recovered, were immune against inoculation with virulent
material. Thus the accuracy of Pasteur's experiments,
and the possibility of attenuation and protective inocu-
lation for swine erysipelas, is proved. This result was
a priori not improbable, as Loeffler had formerly shown
that the bacilli of mouse septicaemia, which so much
resemble the erysipelas bacillus, cause a mild disease in
rabbits, as the result of which these animals are rendered
completely immune; and as also it was known that
swine erysipelas belongs to the class of diseases which
do not recur, one attack protecting against a later
infection.

Nevertheless the result of the vaccination experiments
carried out in large numbers in Baden cannot be re-
garded as being particularly favourable from a practical
and economic standpoint. Of 119 animals inoculated,
6, or 5 per cent., died of erysipelas as the result of the
inoculation, while the average loss from the ordinary
disease is at most only 2 per cent. ; however, the animals
which died as the result of inoculation were, on account
of their youth, of much less value than the animals
which died of erysipelas. It was also ascertained that
the animals which were rendered ill by the inoculation
were able to infect other animals with the fatal disease ;
and, finally, we do not as yet know whether the inocu-
lated swine are protected against the natural infection.
From these considerations it is evident that the final
judgment as to the practical value of Pasteur's protec-
tive inoculation must be deferred till more accurate
experimental evidence has been obtained.

Klein has claimed the discovery of the erysipelas bacillus,
)mt from his statements that these bacilli may be confounded

BACILLI OF SWINE ERYSIPELAS.

with bacterium termo, that the transverse diameter of the
erysipelas bacilli is the same as that of the hay and anthrax
bacilli, further that a superficial scum, as well as a deposit at
the bottom is formed in the fluid cultivations, and, finally,
that the bacilli taken from the cultivations move as actively as
bacterium termo, we may with certainty assume that Klein
has not recognised the true erysipelas bacilli, and, at most,
lias dealt with them in impure cultivations.

Pasteur also has at first probably not recognised the true
infective agents, and has evidently worked with impure cul-
tivations ; and it is a matter of surprise that, nevertheless,
he has obtained these interesting results with regard to pro-
tective inoculation, now confirmed on all sides. Baillet
suid Jolyet (Revue Veter., 1884) also describe the erysipelas
organisms incorrectly as microbes of the form of the figure
of 8, at times arranged in chains, and — in opposition to all
other observations — virulent in guinea-pigs.

Loemer in a case of a pig, which had died of so-called
.swine erysipelas, but in which the disease was evidently
different from the epidemic form, found other bacteria which
caused in guinea-pigs sero- sanguineous infiltration of the sub-
cutaneous tissue and hasmorrhagic affections of the muscles.
Further facts as to this discovery will be mentioned later.

Of special interest is the observation made by Schottelius, A second

rhat in almost all cultivations made from animals which had fP6?),6.8.0^ ,
,.,,,,,.,. , . , bacilli in the

died or this disease, the cultures being made in some cases erysipelas

a very short time after death (within 20 minutes), other larger cultivation •».

bacilli also grew which formed light yellow spherical colonies

in the gelatine. This bacillus, which is described in detail

below, breaks up the gelatine with the formation of a foul

smell, and is thus evidently one of the exciting agents of

I mtref action, and probably comes from the intestine, in the

contents of which Schottelius was also able to demonstrate it.

Hence it is probable that these bacilli are able to penetrate Entrance of

into the body even before the death of the animal, entering these bacilli
i .LI ^i • • . ,. i through tlio

through those parts of the intestinal mucous membrane injure(i

which are denuded of epithelium and ulcerated ; this view is intestine,
directly supported by the observation that these bacilli are
present in largest numbers in the organs in the neighbour-
hood of the intestine (not only in the intestinal wall itself,
but in the mesenteric glands, and in the spleen), while, on the
other hand, they gradually diminish in numbers in the organs
further away from the intestine, and thus only occur rarely
in the lungs and the muscular tissue of the heart. This dis-
covery enables us to draw important conclusions with regard
to the entrance of fungi secondarily in other diseases accom-
panied with injury of the intestinal epithelium.

810 BACILLI PATHOGENIC IN ANIMALS.

Bacillus mimsepticus (Koch).
(Bacillus of Mouse Septicaemia.)
Bacillus of These organisms, first discovered hy Koch, and very

mouse i • i -IT ii«n

septicaemia, closely resembling the bacilli of swine erysipelas, occur
not uncommonly in all sorts of mixtures of bacteria.
If small portions of putrefying fluids, which have been
exposed to the entrance of all kinds of bacteria, are
taken during the early stage of putrefaction and inocu-
lated subcutaneously into, say, twenty mice, one or other
of these animals generally dies of a septicaemia which is
caused by the bacilli of which we are speaking.

The early symptoms of the disease are increased
secretion from the conjunctiva and adhesion of the eye-
lids, lassitude, &c. ; the animal sits quietly with the back
arched, and death occurs in this position 40 to 60 hours
after the inoculation, coming on almost imperceptibly
and without any convulsive movement. Even after
death the mouse generally remains in this position,
while the mouse which has died of anthrax, for example,
lies on its back or its side with its extremities stretched
out. On making a post-mortem examination slight
oedema is sometimes found at the seat of inoculation,
and there is also considerable swelling of the spleen, but
no further alterations. Delicate bacilli are present in
the neighbourhood of the seat of inoculation, in all the
blood vessels of the body, in the blood of the heart, and
more especially in the capillaries of the kidneys and
spleen.

Morphological These bacilli are *8 to 1' p. in length, and about
characters. .% ^t jn thickness. They often occur in pairs or in
fours, forming short threads ; they frequently form small
groups ; they have no spontaneous movement. They
can be rendered distinctly visible by treatment with the
aniline colours, which they readily take up ; cover-glass
preparations of blood are best stained in alkaline me thy -
lene blue, and then decolourised by momentary immer-
sion in very dilute acetic acid; Gram's method also
gives very distinct pictures. For sections the method

BACILLUS MURISEPTICUS. 311

of double staining used for demonstrating the bacilli of
swine erysipelas can be employed.

In the preparations from the blood of the heart the
bacilli show a very characteristic arrangement : they lie
in part in the interior of the white blood corpuscles.
When this is the case the latter are generally much
swollen ; in some of the cells the protoplasm takes on the
stain only very feebly, and the outlines are indistinct ; in
other cases the whole body of the cell consists solely of
thickly aggregated bacilli, which here and there project
from the surface of the disintegrating cell mass. By exami-
nation of the various stages which can usually be recog-
nised in the same specimen we obtain the impression
that the cells are destroyed by the bacilli in their interior,
and not that the bacilli undergo destruction in the cells.

.A

Fig. 87.— Bacilli of mouse septicaemia (after Koch) X 700.
A , blood of a septicaemic mouse, red corpuscles with bacilli between

them.
P, white corpuscles containing bacilli.

The bacilli can be readily cultivated, and grow on the Cultivations,
various nutrient substrata exactly in the same manner
as the bacilli of swine erysipelas (except with the slight
differences mentioned above). On gelatine plates they
form bluish-grey cloudy flakes lying underneath the
surface, which are resolved, under a low power of the
microscope, into a network of delicate threads ; in
jelly puncture cultivations a very delicate bluish-grey
cloud forms around the track of the needle, and this
cloud gradually extends outwards from the line of
puncture till it almost reaches the wall of the vessel
(fig. 86). .

The minutest trace of blood containing bacilli or of a Inoculation on
cultivation is sufficient to set up the disease in mice.
Field mice and guinea-pigs are completely immune ;

31*2 BACILLI PATHOGENIC IN ANIMALS.

sparrows and pigeons are, on the other hand, susceptible.
Kabbits sometimes, but not always, die after inoculation ;
often they only show a local reaction, such as an ery-
sipelatous formation on the ear, which can be traced
over the ear to the parts beyond ; after inoculation on
the cornea an intense inflammatory process occurs in the
eye. Loeffler has made out that rabbits Avhich have
once recovered from this inoculation on the ear, or on
the cornea, are completely immune against any new
attempt to introduce the bacilli, however large the doso
employed.

Bacillus cuniculicida (Koch).
(Koch's Rabbit Septicaemia.)

This septicaemia was obtained by Koch* by inoculation
°f ra^bits with impure river water (the water of the
Panke), and on another occasion with flesh that was
undergoing putrefaction. Numerous other attempts to
obtain the same morbid agents from putrefying materials
were unsuccessful, so that the distribution of this
organism seems to be limited, both as regards place and
time.

Microscopical These organisms present the form of short rods some-
characters. \vhat pointed at their ends ; when stained the ends take
up the dye, while the central portion of the rod remains
unstained ; there is no constriction in the middle, but the
peculiar distribution of the colouring matter readily
leads to the erroneous idea that the organism consists
of two micrococci lying side by side. They do not stain
by Gram's method. Their length is 1'4 /*. and their
breadth "6 to "7 /*. Two and more bacteria often remain
united after division, and thus form apparently longish
rods ; under these circumstances they frequently present
the form of a figure of 8, and are surrounded by a some-
what clear area. Spontaneous movement has not been
observed.

Growth on The bacilli grow readily in broth, in blood serum, and

plates. on nutrient jelly. On gelatine plates small white points

* Mittheil. a. d. Kais. Ges. A., vol. i., p. 94, ff.

BACILLUS CUNICULICIDA. 313

appear on the third day, and these under a low power
present the form of circular discs, with a sharp, dark
outline not quite regular, and of a yellow colour, lighter
towards the periphery. At a some- , ,,

what later stage the dark yellowish ^ ' $^jj)
brown central zone and the clearer JT / ' •' .• *
peripheral zone are often sharply • , &,
marked off from each other, so that Fig.88.— Baccillusof
the colony appears to consist of con- ft^J^&SSJ?

. . ,J rr ^T. .. , (after Koch) X 700.

centric layers. When it spreads at Blood ?f a gparrow
the surface, which only occurs to a showing the nuclei

J of the red blood

very slight extent, and does not corpuscles with

extend further than a millimetre, SSSmtto^

the outline remains sharp, dark,

and for the most part fairly circular, though often

somewhat irregular. The colony presents a finely

granular appearance at this stage. In the puncture In puncture

n- ,. ,i . i ., f i ,1 v „ cultivation*.

cultivations a thin deposit forms along the line of
puncture, and this deposit does not become confluent in
many places, but presents the appearance of discrete
spherical colonies of a somewhat transparent yellowish
white colour. On the surface it spreads in the form of
a flat and limited layer ; in stroke cultivations it forms
a thin layer somewhat thickened at the borders, which
are irregular and serrated ; here and there the line is
interrupted by isolated colonies. The cultivations only
retain their vitality for 4 or 5 weeks.

If the minutest portion of a cultivation is inoculated inociUation on
into a rabbit (a prick in the cornea suffices) the body '
temperature becomes elevated after an incubation period
of 10 to 12 hours, and the breathing becomes slow and
laboured ; ultimately the temperature falls below the
normal, and after the occurrence of some convulsive
attacks the animal dies 16 to 20 hours after the inocula-
tion. On post-mortem examination, the spleen and
lymphatic glands are found enlarged, and the lungs
present a strikingly marbled appearance ; there are no
extravasations of blood, and no peritonitis. The charac-
teristic rods are equally distributed everywhere through-
out the blood ; on sections of the various organs they

314

BACILLI PATHOGENIC IN ANIMALS.

are found in the blood vessels and capillaries ; the Lest
appearances are obtained from sections of lung, stained
with gentian violet. Mice and birds (sparrows, pigeons,
fowls) are as susceptible as rabbits ; guinea-pigs and
white rats are immune ; dogs do not react on inoculation
of small quantities, but after subcutaneous injection of
larger amounts an extensive oedema of the subcutaneous
cellular tissue occurs, and the animals die after two or
three days. No experiments have as yet been made as
to the attenuation of these bacilli ; in successive cultiva-
tions even continued for a long time they retain their
full virulence.

Bacillus cliolercB gallinarum.

(Bacteria of Chicken Cholera, or Fowl Typhoid ;
Microbe du Cholera des Poules.)

In the epidemic disease which occurs in poultry yards,
and which has been known and dreaded for a long time
in France under the title of chicken cholera (although
the symptoms show very little resemblance to those of
human cholera), bacilli were found in the first instance
by Perroncito, then by Toussaint, and later by Pasteur,
and these have proved to be the causal exciting agents
of the disease. These observations have been con-
firmed and extended by Eivolta, Marchiafava and Celli,
and Kitt. Petri has also found bacteria in an epidemic
in a poultry yard, which are probably identical with the
bacilli of chicken cholera.

The disease begins by the fowls attacked becoming
very helpless and tumbling about, the wings hang, and
ultimately the animal sits quietly rolled up in a ball,
with erected feathers. The animals are very somno-
lent ; if they are compelled to open their eyes they
ijppear as if they had awaked from a deep sleep ;
they soon close the eyelids again, and usually
after a slight convulsive attack, die without having
moved from the spot. Very frequently at the height
of the disease there is a slimy diarrhoea, the stools

BACILLUS CHOLERA GALLINARUM. 315

containing very numerous bacilli. The whole course
of the disease is ol'u n very rapid, lasting only a few
hours.

On post-mortem examination the spleen and liver are Post-mortem
found to be enlarged, there is also intense inflammation appea
of the intestinal mucous membrane, especially of the
duodenum, with numerous haemorrhages, and at times
with ulcerations, haemorrhagic infiltration in the perito-
neum, haemorrhagic pneumonia, and numerous ecchy-
moses in the pericardium, in the pleura, and in the
brain.

Large numbers of short bacilli, very similar to those Microscopical

described before in rabbit septicaemia, but somewhat °f

shorter and thicker, are found in the blood of the heart,
and of all the other organs. They have been described
by Pasteur as cocci, but when highly magnified there is
no doubt as to their rod character. The fully-grown
individuals attain a length of about 1 to 1*2 p., and
usually show, when stained, an aggregation of the
colouring matter at the ends, as in the case of rabbit
septicaemia, the dark poles being se-
parated by an unstained central portion.
The bacilli are usually in a state of
active division, and thus many forms
are found which are constricted in the

.,,, ... ,. , , Fig. 89.— Bacilli of

middle, not unlike a diplococcus, and chicken cholera x
also numerous young individuals in 800-

T . T ,-, , ., . -, T i ji Cover glass prepara-

which the length is only very slightly tion from a fresh
greater than the breadth. We can cultivation.
always see, however, with good lenses that even the
youngest individuals are not round, but more quad-
rilateral with parallel contours — in other words, that
they are short bacilli. In sections of the organs the
rod character is usually much more distinct ; they are
found there in varying numbers within the bloodvessels,
sometimes only a few examples, sometimes in dense
masses.

The bacilli of chicken cholera can be readily cul- Growth in
tivated. On plates of nutrient gelatine they appear on estivation*.
the second day as whitish-yellow points, which are seen

316

BACILLI PATHOGENIC IN ANIMALS.

under a low power to be discs of a yellowish-brown
colour with sharp outlines, finely granular, seldom
circular, but as a rule with irregular boundaries.
The centre is of a lightish-yellow colour, towards the
periphery there is a narrow brownish ring, and then a
light border. The superficial colonies form small moder-
ately prominent, transparent drops of a yellowish-white

mil^m/'::

Fig. 90. — Chicken cholera.
Section from the liver of a hen X 700.

colour, they show less of a circular form and are dis-
tinctly granular ; but the zones above mentioned can
still be recognised, and have only become correspond-
ingly broader. In puncture cultivations they form
partly discrete and partly confluent colonies along the
needle track ; on the surface they spread out in a flat
layer, which is somewhat more marked than in the case
of the bacilli of rabbit septicaemia. — On blood serum the
cultivations form a dull, white, thin layer. On potatoes
a wax- like transparent greyish-white and only slightly
prominent layer is formed, which grows slowly and only
at a temperature of about 28° C. Growth of the bacilli
also occurs on hard-boiled white of egg. In neutralised
broth they grow luxuriantly, and cause slight turbidity
of the fluid. — According to Pasteur they soon lose their
vitality in neutralised urine ; they do not grow at all in
yeast water.

BACILLUS CHOLERA GALLINARU.M. 317

Subcutaneous inoculation of the smallest quantity of inoculation on
a cultivation sets up in healthy fowls the S3Tmptoms
described above, and death occurs in 24 to 36 hours.
Pigeons, sparrows, pheasants, mice, and rabbits are
likewise very susceptible to the disease ; guinea-pigs,
sheep, and horses do not as a rule die, but abscesses
form at the seat of inoculation, the pus of which con-
tains large numbers of bacilli. Mice, fowls, and rabbits
can also be infected by feeding them with the cultiva-
tions ; dogs remain healthy even when fed for a long
time with the bacilli. It is probable that the natural
mode of infection in the poultry yards is that the dejecta
of the diseased animals which contain the bacilli con-
taminate the food, and are then swallowed by the healthy
animals.

Pasteur failed to set up a fatal disease in fowls when Filtration of
he filtered the cultivations in neutralised chicken-broth tions.
through plaster or porcelain, but after large doses of the
filtrate there occurred in the first place a short period of
excitement and then moderate somnolence, which after
a few hours ended in recovery. This result is probably
to be explained by the presence of toxic products of the
bacilli in the filtered cultivations. Marchiafava and Celli Transference
have found that the bacilli of chicken cholera can pass
from the mother to the fostus ; such a transference is in
many cases a priori probable, because in chicken cholera
haemorrhages and lesions of the vessels occur in all the
organs, and in this way the organisms pass out of the
blood vessels.

The bacilli of chicken cholera have excited special Attenuationo
interest because Pasteur carried out with them his first andproteSive
experiments on attenuation and protective inoculation. inoculation-
Pasteur observed that old cultivations which had stood
for several months in vessels plugged with cotton wool
had diminished in their virulence, as he concluded, as
the result of the influence of oxygen ; at any rate this
attenuation did not occur when he preserved the cultiva-
tions in sealed vessels containing only very little air.
The bacilli when attenuated retained the degree of
virulence at which they had arrived, even when further

318 BACILLI PATHOGENIC IN ANIMALS.

cultivations were made in broth, and carried through
several generations. If Pasteur inoculated fowls in the
subcutaneous cellular tissue over the muscles of the
breast with these attenuated bacilli, only an inflam-
matory swelling of the cellular tissue, especially of the
muscle, occurred ; the affected portions of the muscle
soon became separated from the healthy by an abscess
wall, so that a sequestrum of the muscular tissue was
formed. This was absorbed with greater or less
rapidity, and usually had completely disappeared some
weeks after inoculation. The fowls which had thus re-
covered were then found to be immune against inocula-
tion with the most virulent bacilli.

Discrepant re- The results of Pasteur's experiments could not be
obseryerstlier confirmed by Kitt and others. Cultivations on potatoes
and gelatine five or six months old, and always exposed
to air, showed the same virulence as fresh cultivations.
It is possible therefore that Pasteur's cultivations, which
were always made in fluids, were gradually overgrown
by other bacteria, and that thus the diminution in
activity was produced.

Bacillus septicus agrigcnus.

Septic earth These bacilli were first obtained by Nicolaier in the
author's laboratory, and at a later period on several
occasions from the earth of manured fields. These
bacilli agree, as regards their size, for the most part
with the two forms before mentioned, but they are usually

Microscopical somewhat longer ; the same peculiar distribution of the

5rs' colouring matter is also at times seen, although not so

frequently, nor so well marked. Kapid division occurs

in cultivations, and hence, as a rule, there is only a trivial

Cultivations, excess of the longitudinal diameter. — On gelatine plates
the colonies present the appearance under a low power
of circular discs, with sharp outlines and of a finely
granular character ; the centre is yellowish-brown, and
the margin greyish-yellow, these two parts being sepa-
rated from each other by a dark ring. These differences
in colour gradually disappear at a later period, so that

BACILLUS SEPTICUS AGRIGENUS. 319

ultimately there are no distinct zones to be seen ; on the
other hand, the granular appearance becomes more
marked ; the circular outline for the most part remains.
In puncture cultivations a thin and but slightly charac-
teristic layer is formed. — Mice inoculated with small
quantities of the cultivations die after 12 to 22 hours, as
also do field mice ; rabbits die after inoculation on the
car in from 24 to 36 hours. On post-mortem examina- Action on

. _ . , ..,. animals.

tion no special abnormalities are found; the bacilli
above described are present in the blood of the heart
and in the capillaries of all the organs, but always in
decidedly smaller numbers than in the two diseases just
described. Farther, the bacilli show a special tendency
to adhere to the blood corpuscles ; the border of a blood
corpuscle frequently has two, three, or four bacilli
attached to it; but the bacteria do not seem to penetrate
into the interior of the cells.

A number of short, fine bacteria, which are similar to
the three species of bacilli just described, have been sembiing the
observed by various authors in the deposit on the human Sen?in'thee

tongue, in the secretions of the mouth, and in the
sputum. In the Hygienic Institute in Gottingen, Krei-
bohm found two bacteria which were chiefly distinguished
from the above mentioned forms by the fact that they
could not be cultivated on any of the ordinary artificial
substrata.

The first species was obtained on two occasions from First species.
the deposit on the tongue by the inoculation of some
mice with this deposit; the animals died after a few
days, and large numbers of these bacilli were found in
the blood. The rods resemble very closely those of
rabbit septicaemia, but they are somewhat longer and
more pointed at the ends; they do not show any
constriction in the middle, but take up the colouring
matter only at the poles, leaving a clear zone in the
middle. In the blood they occur singly or in small
groups, seldom in the form of threads composed of two

820

BACILLI PATHOGENIC IN ANIMALS.

Inoculation
from animal
to animal.

.Failure of
cultivation
experiments.

Second
species.

or three members. — The blood containing the bacilli
when inoculated on mice in the quantity of about one
drop always produced the same disease in 80 inoculations
continued in series : on the first day no alteration could
be observed in the animals inoculated ; on the second
day they were lazy, they sat quietly with erected back,
and the eyelids were stuck together ; death occurred as
a rule after two or three days, at times, however, not
till after five days. On post-mortem examination nothing
abnormal was found, except very marked enlargement
of the spleen, and slight enlargement of the liver. In
sections of the organs small groups of bacteria were
found within the capillaries, but they were not particu-
larly numerous ; they were only present in very large
numbers in the lungs. Eabbits are relatively but little
susceptible; after inoculation with small quantities of
blood only a transitory illness resulted ; after subcuta-
neous injection of larger quantities of blood the animals
died after two or three days, and the bacilli showed the
same distribution as in the case of mice. Field mice
were very susceptible ; inoculation on a fowl was without
result. Cultivations were frequently attempted with the
most varied solid and fluid substrata, and at various
temperatures ; nevertheless they all failed, while control
experiments with the bacteria of rabbit septicaemia were,
without exception, successful.

The second species was isolated in a similar manner
by the animal body (mice) from a deposit on the human
tongue. These organisms consisted of short rods rounded
at the ends, and slightly constricted in the middle ;
when stained they resemble a figure of 8, the stain being
more intense at the poles ; they are also surrounded by
a clear area, and on the whole they most closely resemble
the bacilli of chicken cholera. The rods were present in
large numbers in the blood of the heart of mice ; in sections
of the organs they were found inside the capillaries, but as
a rule in isolated masses, and not more numerous in
the lungs than in the other organs. The inoculation of
the disease on mice was carried on successfully through
40 or 50 generations with minute quantities of blood ;

BACILLUS SEPTICUS AGRIGENUS. 321

death occurred much more quickly than in the case of
the first species, often even after 18 hours, at the latest
after 40 hours. Kabbits were completely immune.
Cultivation experiments showed at most a multiplication Cultivation
of the bacteria in the blood inoculated on the first sub- SSS^enta
stratum ; further attempts at inoculation were always unsuccessful,
unsuccessful.

The following bacteria isolated from saliva by other
authors are either identical with one or other of these
species, or it may be different from them, but this can-
not be decided on account of the absence of sufficient
-characteristic distinctive points.

Pasteur obtained a microbe from the saliva of a child Pasteur's
which had died of hydrophobia. Kaynaud and Lanne- hydrophobia,
longue had discovered that the inoculation of such saliva
on rabbits caused the illness and death of the animals ;
Pasteur confirmed these experiments, and cultivated
a micro-organism from the blood of the rabbits in
veal broth, this organism being rod-shaped and some-
what constricted in the middle in the form of a figure
of " 8 " ; the organism was only 1 p. in diameter, and
was surrounded by a gelatinous substance like an
aureole. In the cultivations these rods were said to be-
come converted into chains of cocci. Fowls and guinea-
pigs were not susceptible to the action of the microbe. —
Although at first Pasteur supposed that he had ob-
tained the infective agent of hydrophobia, he succeeded in
setting up the same disease, and found the same organ-
isms in rabbits inoculated with the saliva of healthy
human beings. In like manner Vulpian was able to set other similar
up, by inoculation of normal saliva on rabbits, a disease
which ended fatally in two days, and which could be
transmitted from animal to animal by small quantities
of blood. — Fraenkel also obtained a similar result by the
inoculation of his own saliva. (See Literature, p. 37.)
Klein has set up infective diseases in rabbits and
mice by the sputum of patients suffering from pneu-
monia, and he has described the infective agents of
these diseases as belonging to various species of micro-

21

322 BACILLI PATHOGENIC IN ANIMALS.

cocci. It is possible that in these cases also the bacteria
belonged to the group here described. — In like manner
the septicaomia formerly described by Davaine, which is
fatal to rabbits and guinea-pigs but not to pigeons,
seems to have been due to similar bacteria.

Group of Another smaller group of bacteria is formed by short,

resembiingethe t]bick cells> egg-shaped when young, and resembling
hacim°nia ^e Pneumom'a bacilli; like these they are often sur-
rounded by a sheath which can be stained, and in punc-
ture cultivations in gelatine they give rise to nail-shaped
growths, and on potatoes to thick gelatinous deposits.
It is at times impossible to distinguish the species
belonging to this group from each other either by the
microscope, or by the appearance of the cultivations,
and this can only be done by experiments on animals.

Bacillus cmssus sputigcnus (Kreibohm).

Kreibohm's These organisms were obtained by Kreibohm on two
bacilli^11 * occasions from sputum, and on one occasion from the
fur on tlie toi]gue- TneJ present the form of short,
thick bacilli, or oblongs with rounded corners ; they
are often bent like a sausage, or twisted. Immediately
after division the longitudinal diameter is only about a
half greater than the transverse, but later on the
difference is more marked, so that before new division
takes place the bacilli are three or four times as long as
thick. The bacilli are often seen to be connected
together, either while division is going on, or after
division has occurred, but longer threads do not occur.
The bacilli, both from blood and from cultivations,
frequently present abnormal forms, often showing
swollen ends or irregular contours, and here and there
converted into shapeless masses. The bacilli stain
readily, and retain the stain on treatment by Gram's
method ; at higher temperatures (35° C.) they appear to
Cultivations, form spores. — The bacilli can be cultivated on a number
of different substrata. In gelatine plates they form
distinct greyish-white points after about 36 hours,

BACILLUS CKASSUS SPUTIGENUS.

323

these points soon rising above the surface and then
spreading out in the form of greyish-white round gela-
tinous drops, which project considerably above the
surface of the jelly. Under a low power the youngest
colonies appear circular, of a greyish-brown dark colour
with dark points, or with short dark lines over the
whole surface. The superficial larger colonies appear
distinctly lighter, irregular in outline, and the surface. —
more especially at the border — is distinctly granular.
In puncture cultivations the organisms grow very
quickly, in about 24 hours, and show the typical nail-
shaped appearance. On potatoes they form a thick,

Fig. 91. — Bacillus crassus sputigenus (Kreibohm) X 700.
Cover glass preparation from the blood of the heart of a mouse.

greyish-white moist and shining layer, similar to the
cultivation of the pneumonia bacilli, but somewhat
flatter and tougher, though as a rule scarcely distinguish-
able from the latter. — Mice die after inoculation with Experiment
small quantities of the cultivation in about 48 hours ; on animals-
numerous bacilli are found in the blood of the heart,
and in all the capillaries, in largest numbers in the
liver. Babbits are not markedly affected by small doses,
if introduced by inoculation, but after intra -venous
injection of small doses they die within 48 hours, large
masses of bacilli being found in the blood. Large Action of
quantities of the cultivation injected into the veins larger doses-
cause in rabbits, and to a still more marked degree in

324

BACILLI PATHOGENIC IN ANIMALS.

dogs, diarrhoea, with at times bloody stools, and death
within 3 to 10 hours ; on post-mortem examination all
the appearances of an acute gastro-enteritis are found.

Microscopical
characters.

Bacillus pseudopneumonicus (Passet).
Pseudo- These organisms have been cultivated on two occa-

pneumomc , _ , . . . ~

bacteria. sions by Passet from the pus of abscesses in man.*
They are oval or round, seldom elongated, cells resem-
bling £hose of the pneumonia bacilli, but with a greater
tendency to the formation of rounded forms. Their
transverse diameter is *87 ^., their longitudinal I1 16.
In preparations which have been taken from the animal
body, or from cultivations grown at the body tempera-
ture, the bacteria are seen to be surrounded by a sheath
which takes up the colouring matter.

Cultivations. In gelatine plates white points appear after 24 hours,
and under a low power present the form of round, finely
granular, grey, and later often very dark discs, with
regular sharp outlines. On the surface the colonies
form greyish-white prominent nodules of about the size
of half the head of a pin ; the pneumonia colonies are
somewhat thicker and whiter. In puncture cultivations
the pseudo-pneumonia bacillus grows only on the sur-
face, being a pure ae'robe, and forms on the surface
greyish-white hemi-spherical glistening nodules ; it does
not grow at all along the track of the needle. On
blood serum it forms a thin greyish-white layer; on
potatoes kept at 37° C. a thick white shiny moist layer
appears in 24 hours, without any development of gas,
or formation of bubbles. — In mice, rats, guinea-pigs,
and rabbits the injection of Passet 's bacteria into the
pleura causes pleuritis, and into the abdomen, peri-
tonitis ; subcutaneous inoculation kills mice from
septicaBmia, but as a rule only causes the formation of
abscesses in rats, guinea-pigs, and rabbits ; 43 mice
treated by inhalation of the cultivations remained well.

* They are described by the author as cocci, but on account of the
analogy with the pneumonia bacteria, and for the reasons given with
regard to the latter, these organisms have been included here under
the bacilli.

Experiments
on animals.

BACILLUS SEPTICUS SPUTIGENUS. 325

Bacillus septicus sputigenus (Fraenkel).

These organisms have been repeatedly observed by Fraenkel's
A. Fraenkel * in the rust-coloured sputum of patients bacteria,
suffering from pneumonia. These microbes have the
appearance of cocci, resembling very much the pneu-
monia bacteria, and like these they are surrounded by a
broad capsule. They do not grow on gelatine at the
ordinary temperature, but they grow on agar and blood
serum at the body temperature ; in the latter they form
a veil-like almost transparent layer, or a deposit like
drops of dew. Babbits die after subcutaneous inocu-
lation in 24 to 48 hours, with the symptoms of acute
septicaemia. — Fraenkel thinks it probable that these
bacteria have a causal relation with human pneumonia
and with the empyemata which develop after pneumonia.
A more detailed description of these organisms has not as
yet been furnished.

Bacillus pncumonicus agilis (Schou).

These organisms were cultivated by Schou on three Bacteria of
occasions from the lungs of rabbits which had become
affected with pneumonia after section of the vagus nerve.
They present the form of short thick rods, or more
elliptical cells often occurring in pairs, or, seldom, in
chains of three or four members. They do not stain by
Gram's method. When examined in drop cultivations
they show very active spontaneous movements ; in
gelatine plates the colonies of the bacilli appear under a
low power as round, dark, granular discs, with a slightly
rough surface and borders. After 20 to 24 hours
liquefaction of the gelatine commences, and even under
a low power we see very marked movements in the middle
of the colony. At this stage the borders appear as if
surrounded by a small crown of rays, but soon after-
wards the gelatine becomes entirely liquefied. On soli-
dified blood serum the bacillus grows very slowly, and
leads to slight liquefaction of the serum ; in broth it
forms a plentiful yellowish deposit at the bottom of the
* Lit., p. 37.

326 BACILLI PATHOGENIC IN ANIMALS.

vessel ; on potatoes it forms a reddish chamois-coloured
flat layer, which extends very quickly. — Cultivations
introduced into the lungs of rah bits through the wall of
the chest, or by injection into the trachea, or hy inhalation
into the lungs, set up a violent pneumonia, which presents
exactly the same appearance as the vagus pneumonia,
in which the bacilli were originally found.

Bacillus diphtheria columbarum (Loeffler).

Bacilli of JQ fowis an(j pigeons we not uncommonly find epi-

diphtheria. demies of a disease resembling human diphtheria, which
begins with hyperaemia of isolated spots of the mucous
membrane ; at a later period these spots become covered

Symptoms of with a thick light yellow deposit. In the case of pigeons
sease. ^Q base of the tongue, the mucous membrane of the throat,
and the angle of the mouth, are more especially attacked ;
in fowls the usual seats are the tongue, the palate, the
nasal cavities, the conjunctivas, and the entrance of the
larynx. The temperature of the affected animals is
somewhat elevated. The disease runs its course as a
rule within two or three weeks, and may at times
last for some months with repeated exacerbations ; 80
per cent, of the fowls affected die ; of the pigeons, how-
ever, a smaller proportion. Young animals, and those
belonging to pure breeds, are more especially predisposed
to the disease.

Microscopical Loeffler* was able to isolate, from the exudation of a
pigeon which had died with these symptoms, bacilli
which were only slightly longer and somewhat narrower
than the bacilli of rabbit septicaemia, and were rounded
at the ends, and usually occurred in groups. In sections
of the lungs, and more especially of the liver, the rods
were found in the interior of the blood vessels, forming

Cultivations, masses similar to those of the typhoid bacilli. — On
nutrient gelatine they form at the deeper parts whitish
spheres, on the surface whitish layers ; under a low
power the colonies present a yellowish-brown appear-
ance. On blood serum they form a greyish-white

* Mitth. a, d. Kaiserl. Ges. Amt., vol. ii.

BACILLUS DIPHTHERIA COLUMBARUM. 327

semi-transparent layer ; on potatoes a deposit which is
only distinguishable from the surface of the potato by
having a somewhat greyer colour. — Pigeons inoculated Experiments
subcutaneously with pure cultivations of these bacilli on ammals-
are attacked by inflammations ending in necrosis ; after
inoculation on the mucous membrane of the mouth
a morbid process develops, which completely coincides
with the natural infective disease. — Sparrows and rabbits
are susceptible to the action of the bacilli ; fowls, guinea-
pigs, rats, and dogs are immune, or only show a tran-
sitory local aifection. Mice show very characteristic
effects ; they die as a consequence of subcutaneous inocu-
lation in about five days, and the short bacilli, described
above, are found in the blood, and in all the organs,
most numerous in the liver ; they lie everywhere in the
interior of the blood vessels, and often also in the interior
of colourless blood cells. To the naked eye the peculiar Characteristic
character of the liver is most striking in the mice, as appe'araiufeT
also the marked swelling of the spleen, and the patchy in mice-
redness of the lungs ; the liver has a marbled white
appearance, due to the fact that in the pale red liver-
tissue numerous white irregularly limited patches were
present. Under the microscope no liver-tissue can be
seen in the neighbourhood of these patches, and the
nuclei do not stain at all ; in the centre of the patches,
however, there are dense masses of bacilli within the
vessels, which have evidently led to the death of the
surrounding tissue of the liver over a considerable area. —
As this post-mortem result is found in all the mice
inoculated, we have in the inoculation of mice with these
bacilli the best means of recognising them.

These bacilli must therefore be looked on as the ex-
citing agents of pigeon diphtheria. As they were not
found in human diphtheritic membranes, even after the
most careful microscopical examination, we must con-
clude that the two forms of diphtheria are not etiologi-
cally the same. The view that human beings can
become affected with diphtheria from infection from
diseased pigeons and fowls has been repeatedly ex-
pressed, but has been objected to by a number of

328

BACILLI PATHOGENIC IN ANIMALS.

human
diphtheria.

Delation cf authors (for example, Magnin*). Kecently Gerhardt and
theria to Stumpf f have published cases of infection of man from
pigeon diphtheria ; but in none of these cases has it been
shown that the disease in man was true contagious
diphtheria; on the other hand, it is probable that
milder affections of the mucous membrane were present.
It is possible that these affections might be caused by
the diphtheritic bacteria of pigeons or fowls, especially as-
we know from the experiments on animals that many
kinds of bacilli can set up diseases of the mucous mem-
brane of the most various intensity, and even diseases
accompanied by the formation of membrane, and yet
these affections cannot be included under the term con-
tagious diphtheria ; and further, severe diphtheritic at-
tacks would be of much more frequent occurrence in
man, in association with epidemics in poultry yards and
among pigeons, if the infective agents in the two cases
were identical. — Further, according to Loeffler's experi-
ments, the diphtheria of fowls is apparently different
from that of pigeons, and the etiology of the former is,
as yet, not at all made out.

Bacilli of the
diphtheria of
calves.

Symptoms and
post-mortem
appearance sin
the diphtheria
of calves.

Bacillus diphtheria vitulorum (Loeffler).

The diphtheria which occurs in calves in an epidemic
form is characterised by great lassitude of the animals,,
flow of saliva, yellow exudation from the nose, imperfect
attacks of coughing, and diarrhoea. On the mucous mem-
brane of the cheeks, of the tongue, and of the hard palate,
we find yellow deposits extending deeply into the tissue ;
the entrance to the larynx and the nasal cavities are
often affected at the same time ; and similar infiltrations
have also been observed in the skin between the toes of
the fore-feet. Death sometimes occurs on the fourth or
fifth day, usually, however, the disease lasts for several
weeks. On post-mortem examination we find besides
these deposits similar alterations in the mucous mem-
brane of the large intestine, and deposits in the lungs

* Magnin, Gaz. des hopit., 1879.

t Gerhardt, Lit., p. 18.— Stumpf, Dewtsch., Arch. f. Uin. Med.,vol. 36,

BACILLUS DIPHTHEKLE VITULOBUM. 329

varying in size from a pea to a nut, of a greyish-yellow
colour, and in part suppurating. — On microscopical ex-
amination of the deposits in the mucous membrane
Loeffler* found, quite at the surface, numbers of all
kinds of bacteria, more especially of micrococci ; then
follows a broad, unstained zone, the structure of which
is unrecognisable, and in which there are no bacteria,
and it is only close to the tissue itself that we find at
first single, and then as we go deeper numerous long
bacilli, ultimately arranged in long wavy bundles and
dense masses, separated from the tissue by a narrow un-
stained zone on the farther side of which we see a dense
nuclear infiltration of the tissue. The majority of these Microscopical
bacilli are united together to form longish threads ; the the bacilli,
individual segments are about five or six times as long as
broad ; their thickness is about half that of the bacilli
of malignant oedema. As Loeffler was able to demon-
strate the presence of these bacilli with the same
characteristic arrangement in seven cases of diphtheria
in calves, we are justified in drawing a conclusion as to
their causal connection with the disease from the
constancy with which they occur. — Cultivation experi- Cultivation
ments have as yet led to no result ; nutrient jelly, Shou?en
sheep's blood serum, &c., have remained entirely sterile result-
after inoculation ; in calves' blood serum a whitish
rim is formed around the pieces of organs which are
planted on it, this ring consisting exclusively of the
long bacilli, but attempts to inoculate fresh serum, from
this rim failed. — On the other hand, the fresh diph-
theritic deposit was inoculated with success on mice,
while guinea-pigs and rabbits did not show any charac-
teristic disease. The mice died after 7 to 30 days ; Inoculation on
a greyish-yellow speckled infiltration extended from the ai
seat of inoculation, involved the whole of the wall
of the belly or back, reached often as far as the peri-
toneal cavity, and enveloped kidneys, liver, and intestine
in yellow masses of exudation. Other mice could be
successfully inoculated from this infiltration. In all the
affected animals it could be shown by the microscope

* Mltth. a. d. Kaiserl. Ges. Amt., vol. 2.

330

BACILLI PATHOGENIC IN ANIMALS.

that, as in the case of the calves, the infiltration was
occasioned by the long bacilli. — Further proof of the
etiological r6le of these bacilli must be furnished by
more extensive cultivation experiments.

Group of
bacteria
which set up
gastro-
enteritis.

Earlier experi
ments with
mixtures of
bacteria.

Later experi-
ments with
pure cultiva-
tions.

Another group of bacteria characterised by similarity
in their pathogenic action is formed by those bacilli
which set up a more or less severe gastro-enteritis in
the animals ordinarily employed for experiments, such
as dogs, rabbits, and guinea-pigs, the disease occurring
when the bacteria are injected in relatively large numbers,
either into the veins, or subcutaneously. Similar symp-
toms were formerly often obtained experimentally by
the employment of mixtures of bacteria, and Virchow*
observed, as long ago as 1847, vomiting and diarrhoea
with ultimate collapse, in animals after injection of a
fluid obtained from putrid fibrin. Among more recent
writers we need only mention Popoff,f who obtained
similar results by the injection of a mixture of yeast,
and also of putrid Pasteur's solution; and Blumberg,J
who worked with putrefying dog's blood, and with
the water employed for the maceration of dog's flesh,
and set up violent vomiting and rapid death after intra-
venous injection, and milder and less constant symptoms
after injection subcutaneously. On post-mortem ex-
amination of the animals, the severe cases showed the
appearances of a hsemorrhagic gastro-enteritis with
marked swelling, and often deep ulceration of Peyer's
patches. In milder cases there was only hyper aemia of
the stomach and intestines, and swelling of the follicles.

After the elaboration of the methods for the pure
cultivation of organisms, experiments have been made
with different species of bacteria, and cultivations
of these bacteria have set up the same morbid
symptoms and the same anatomical appearances after
intravenous, and sometimes after subcutaneous in-
jection, as was done by the mixtures formerly employed.

* Handb. der spec. PathoL u. Therapie, vol. i., p. 242.
f Berl. klin. Woch., 1872, Nr. 43.
t Virch. Arch., vol. 100, p. 377.

BACILLI WHICH CAUSE GASTRO-ENTEKITIS. 331

The effect obtained is, however, not uniform, but
varies according to the virulence of the individual
species, as well as according to the number of bacteria
introduced and the seat of their application. After Symptoms in
the injection of large quantities into the veins the the animals-
animals become collapsed in a very short time and
die in from one to three hours. Where smaller
quantities are employed vomiting sometimes occurs,
followed by profuse diarrhoea, the stools being often
mixed with blood, and ultimately collapse, and death
occurs after 12 to 24 hours. Some species of bacteria
cause a passing diarrhoea, without any further bad
result, after intravenous injection of very small doses
or after the subcutaneous introduction of medium
doses. — We cannot as yet properly explain this action
of the bacteria. We do not usually find, either in the
acute or in the protracted cases, any sufficient multipli-
cation of the bacteria injected to explain the phenomena,
and it has also been observed on some occasions that
the same results follow the injection of sterilised
cultivations. These two facts seem to indicate that we
do not have here to do with the immediate action of the
bacteria, but with the toxic effect of a substance which
has been produced by the bacteria. More elaborate
investigations will probably give us information as to
this point.

The organisms which act in this way cannot be
looked on in all cases as specific pathogenic organisms ;
some of them are mainly saprophytes, or exciting
agents of putrefaction, while many belong to the
forms of bacteria previously described, which, when
inoculated in small quantities, set up diseases, mostly
forms of septica3mia, which run a slower course, but, on
the other hand, when introduced into the blood stream in
large doses, lead to the sudden illness just described.
Thus, for example, we obtain these results with the Enumeration
bacilli of rabbit septicaemia, in a very marked manner bacteria be-
with the bacillus crassus sputigcnus, the bacillus of lon^n^ to this
pneumonia, and, among the bacteria which are chiefly
saprophytic, with the bacillus ruler indicus. It must

332

BACILLI PATHOGENIC IN ANIMALS.

be mentioned that very many of the other kinds of
bacteria, even the pathogenic kinds, when introduced
even in very large quantities into the blood stream, do
not produce this effect ; thus the typhoid bacilli,
bacillus tetragenus, the pyogenic cocci, the anthrax
bacilli, and many others when introduced in enormous
doses are either without, effect, or set up specific
diseases after they have gradually spread and multiplied
in the body.

The following are some of the bacteria which set
up these intestinal symptoms in the most marked
manner : —

Toxic lactic
acid bacilli.

Experiments
on animals.

Bacillus oxytocus perniciosus (Wyssokowitsch) .

These organisms were isolated by Wyssokowitsch in
the author's laboratory from milk, which had stood
there for a considerable time. They present the form
of short bacilli with rounded ends, somewhat thicker
and shorter than the ordinary lactic acid bacteria. They
form on gelatine plates at the deeper parts small
yellow colonies, which under a low power have a circular
appearance, are sharply outlined, finely granular, and
brownish -yellow in colour. On the surface the colonies
spread to the extent of about 1-J mm., they are greyish-
white in colour, round, raised, and show under a low
power a sharp outline, and light brown colour. In
puncture cultivations a nail-shaped growth is formed at
first, at a later period the cultivation extends super-
ficially over the whole surface of the gelatine. In stroke
cultivations a rapidly increasing deposit is formed of a
yellowish -white, or greenish colour. — A small quantity
of the cultivation added to sterilised milk causes co-
agulation and acid reaction within 24 hours. Neither
the milk nor the cultivations have any odour. — Small
doses inoculated on mice or rabbits have no effect at
all. Mixtures prepared from one or two test tubes, and
injected into the aural vein of rabbits, caused in each of
six cases death within three to twenty-two hours. Violent
diarrhoea set in about three-quarters of an hour after

BACILLUS CAVICIDA. 333

the injection. On post-mortem examination there was
found in all cases intense and often hsemorrhagic inflam-
mation of the intestinal mucous membrane.

Bacillus cavicida (Brieger).

These organisms present the form of very small rods Brieger's
about twice as long as broad ; they were isolated by !acnu~Plg
Brieger* from human faeces. They form colonies on
nutrient jelly composed of irregular concentric rings ;
the cultivations present an appearance resembling that
of the scales on the back of a tortoise. On potatoes
they form, pretty quickly, dirty yellow masses. Guinea-
pigs are killed without exception within 72 hours by the
subcutaneous inoculation of the most minute quantities
of the cultivation; rabbits and mice are for the most
part immune ; if guinea-pigs are fed with the cultivation
no bad result follows. Kochf has stated that the guinea-
pigs killed by subcutaneous injection show alterations
in the small intestine, marked injection of the mucous
membrane, and a large quantity of thin fluid contents ; in
short, similar symptoms to those formerly obtained by
the subcutaneous injection of mixtures of bacteria.

Bacillus coprogenus parvus (Bienstock).

This is an extremely small slowly-growing bacillus, Bienstock's
obtained by Bienstock on several occasions from human
fasces. They are only slightly longer than broad, so
that it is only under high powers that the rod form can
be distinctly seen ; they grow very slowly on nutrient
jelly; in the course of weeks the cultivation extends
from the line of inoculation to a distance of scarcely
1 mm., and forms a scarcely visible layer on the nutrient
soil. — If white mice are inoculated with a cultivation
marked O3dema occurs in the neighbourhood of the
seat of inoculation within 10 hours ; the animals die
24 hours later ; after death the bacilli can be dernon-

* Zeitschr.f. physiol. Chem., vol. viii., p. 308.

f Conferenz zur Erorterung der Cholerafrage, 2 Jahr.

334

BACILLI PATHOGENIC IN ANIMALS.

strated in small numbers in the blood of the heart. A
rabbit showed after inoculation on the ear erysipelatous
swelling, followed by profuse diarrhoea, and death occurred
eight days after inoculation. On post-mortem examina-
tion catarrh of the intestinal mucous membrane was the
only abnormal condition found. — Further experiments on
animals with this bacillus are desirable.

Bacterium coli commune (Escherich).

Microscopical
characters.

These bacilli were obtained by Escherich* from the
faeces of children nourished exclusively with their
mothers' milk. They are short, slightly curved rods,
their length varying from 1 to 5 /*., and their breadth
from *3 to '4 /*. They stain intensely with aniline
colours, but do not retain the stain when Gram's method
is employed. When examined in drop cultivations they
Cultivations, show slight mobility. On nutrient jelly the deeply
seated colonies present the form of yellow granular
discs ; the superficial ones show a white lateral extension
with a homogeneous granular appearance, or star-
shaped and wrinkled. On agar and blood serum they
grow in the form of white deposits ; on potatoes they
form a soft layer of the colour of maize or yellow peas.
The bacilli slowly coagulate milk with the formation of
acid ; in solutions of grape sugar they set up fermenta-
tion.— When a piece of a cultivation on potato about the
size of a lentil is mixed with sterilised water, and injected
into the veins of the neck of rabbits and guinea-pigs,
the animals die after a few hours, or at latest after three
days, with symptoms of elevation of temperature and
violent diarrhoea. On post-mortem examination the
duodenum and the upper coils of the small intestine
show a rose-coloured hypersemia, while the caecum and
colon have usually a normal appearance ; Peyer's patches
show alterations similar to those seen in the early stage
of typhoid fever. In some cases we also find injection
of the peritoneum and exudation into the peritoneal
cavity. Subcutaneous injection of larger doses produce
the same effect in guinea-pigs.

* FortscJtritle der Medicin.^ vol. iii., 18S5, IsTr. 16.

Experiments
on animals.

BACTERIUM LACTIS AEROGENES. 335

Bacterium lactis aerogcnes (Escherich).

This organism was found, along with the previous A second
one, in the faeces of infants. It consists of short Sfeft^es'S11
generally constricted rods with rounded ends, on an infants,
average 1*4 to 2 /*. in length, and *5 /*. in breadth, as a
rule occurring singly either as rods constricted in
middle, or as pairs of rods ; not motile. These organisms Cultivations,
grow on nutrient jelly like the pneumonia bacteria; in
plate cultivations they form round colonies, which spread
on the surface and form raised points of a porcelain white
colour. In puncture cultivations they grow luxuriantly
along the track of the needle, the needle track being
filled with a number of small white spheres arranged
like a string of beads with, at the upper part, a knob-
like swelling ; at the surface the colonies show a limited
growth, arched like the head of a pin, and of a soft con-
sistence. On potatoes they form a whitish-yellow creamy
layer full of gas bubbles. Milk coagulates with the for- Formation
mation of lactic acid in the course of 36 to 48 hours, at lactic acid'
the ordinary temperature ; in solutions of milk sugar
and grape sugar the organisms cause intense fermenta-
tive action. In sugar solutions they appear to form
terminal spores. When sugar is present the bacteria
are also able to grow when oxygen is excluded, and at the
same time to cause fermentation, while without sugar
they cannot live in the absence of oxygen. — Experiments Need for
on animals gave the same result as with the species oxygen-
previously mentioned, but the action was somewhat less
intense.

Bacillus Neapolitans (Emmerich).

A bacillus which appears to belong to this group of Bacillus found
bacteria was isolated by Emmerich* during the epidemic
of cholera in Naples, in 1884, from the organs, and
later from the intestinal contents of patients who had nad died of
died of cholera. This organism presents the form of c
short rods, with rounded ends, about '9 p.. in breadth,

* Emmerich, Arch. f. Hygiene, vol. iii., 3 & 4 Heft. — Buchner, ibid.

336

BACILLI PATHOGENIC IN ANIMALS.

Cultivations.

Microscopical and at times forming egg-shaped or even more elongated
cells, without or with very slight spontaneous move-
ment. In certain nutrient solutions (cane sugar, extract
of meat, and peptone) longer rods and threads are formed,
according to Buchner ; in glycerine jelly various in-
volution forms appear, characterised by slight thicken-
ing of the rod, and by staining only at the ends. — On
gelatine plates the bacilli form colonies in the substance
of the jelly, which present the appearance, under a low
power, of round, and later irregular, almost egg-shaped
colonies with sharp outlines, of a brownish-yellow colour,
highly refracting, and distinctly granular in the interior.
On the surface of the gelatine the colonies spread to
about ten times the diameter of the deeper ones, and lie
on the surface like scales, of a cartilaginous or ground

glass appearance, showing
rainbow colours with trans-
mitted light. Under a
low power it can be seen
that the limiting line is
markedly irregular or lo-
bular; the interior shows
two zones, a peripheral

Fig 92.

a. Preparation from a piece of mucus , , -,

from the rice water contents of 0 n 6, C 1 C a 1% C 0 1 0 U r 1 e S S,

the human intestine x 700 faintly granular: and a

b. Preparation from the peritoneal •> h '

exudation of a guinea-pig which central One, yellowisll-
had died after subcutaneous in-
jection of the Naples bacteria
(stained with aniline fuchsine) X
700. (Both after Emmerich.)

Experiments
on animals.

brown towards the middle,
and equally granular.
Where the colonies are
more markedly developed, we can also notice radially ar-
ranged, though but slightly marked furrows (Buchner*).
— On potatoes the bacilli grow at 37° C., in the form of
a brownish-yellow gelatinous layer.

When Emmerich injected large quantities of the pure
cultivations of this organism under the skin, into the
lungs, or into the peritoneal cavity of guinea-pigs, death
occurred in from 30 to 42 hours, and, on examination,
hyperaemia of the intestinal and gastric mucous mem-
brane, and even hsemorrhagic erosions and superficial
* Arch. f. Hygiene, vol. iii., 3 Heft.

BACILLUS NEAPOLITANUS. 837

sloughs on Peyer's patches were found. Where the

dose was smaller the course of the disease was more

protracted, and in these cases the ulcerations in the

intestine were more extensive and deeper. If the culti-

vations were injected into the peritoneal cavity death

generally occurred in 8 to 10 hours.— Cats were less

susceptible, relatively larger quantities of the culti-

vation being required in order to cause infection ; and

still larger quantities were necessary in the case of

dogs and rabbits. Of the dogs infected only one died

on the third day, while the others recovered after

being ill for several days. A monkey died after

42 hours, and showed similar alterations in the intes-

tine ; Peyer's patches were of a dark brownish-red

colour, and distinctly swollen. The guinea-pigs as

a rule passed pulpy motions during life ; the cats

suffered from vomiting and diarrhoea ; the monkeys had

also vomiting, with repeated watery stools. — From the

results of the experiments on animals, and of the proof

furnished by cultivation that the bacilli were present in

the blood and in all the organs of nine patients who had

died of cholera, and that they were also present in the

blood of patients in the last stage of the disease,

Emmerich has come to the conclusion that these organ-

isms are the exciting agents of cholera. Nevertheless,

the results of the experiments on animals did not differ

in any important particular from those obtained by the

numerous forms of bacteria mentioned above and the

method employed by Emmerich to demonstrate the

presence of bacilli in the organs was by no means free

from error. In more recent investigations made on Occurrence of

eight cholera bodies in Palermo, Emmerich and Buchner

were unable to confirm the occurrence of these organ- of patients

0 suffering from

isms in the blood and in the internal organs, but found cholera.
them chiefly or only in the intestines and lungs.

It is evident that the presence of these organisms in
the intestines of cholera patients can only be of sig-
nificance if it is shown that the same bacillus is not
present in the normal intestine, nor in intestines in
which any other pathological process is going on. Such

22

338 BACILLUS PATHOGENIC IN ANIMALS.

proof, however, does not appear to have been furnished ;
Occurrence of in Koch's laboratory, as well as in the author's, u

the same ,

bacilli in the bacillus has been repeatedly isolated from the intestinal
teatine. contents of man and animals which is absolutely identical

with that described by Emmerich both as regards micro-
scopical characters, growth in cultivations, and patho-
genic action. (The bacterium coli commune obtained
by Escherich from the intestinal contents shows accord-
ing to the description only very unimportant differences,
due probably to differences in the nutrient substratum,
and it is possibly identical with the bacillus of which
we are speaking.) Hence there is no ground for the
assumption that Emmerich's bacilli play any etiological
role in the cholera process ; on the contrary, they repre-
sent a species of bacterium which occurs frequently in
the intestine, and which corresponds in its pathogenic
action on animals with other intestinal bacteria.

Bacillus necrophorus (Loeffler).

Loeffler's This organism was obtained by Loeffler,* by the

cause necrotic inoculation of small particles of broad condylomata into
processes. the anterior chamber of the eye of rabbits. The bacilli
are of varying length, but of uniform thickness, and
they often form long thin threads, with a slightly wavy
Cultivation outline. They do not grow on the ordinary nutrient
experiments . mefa&} on]y slightly in horses' serum and in chicken
broth, and best in neutralised rabbit broth. A whitish
down is formed after about 3 days around the pieces of
the organs which are placed in the rabbit broth, so that
the particles of tissue appear as if they were enveloped
in cotton wool ; after a few days numerous white flakes
are seen floating in the fluid consisting exclusively of a
dense network of these bacilli, which have grown in the
form of long threads. Here and there swellings are
found in the threads which may be looked on as involu-
tion forms, and there are in addition light stained spots,*
which, however, do not, on the whole, give the impres-
inoculationon sion of spores. — If rabbits are inoculated on the ear, or

* J/trtA. a. d. Kaiserl Ges. Ami., vol. ii., p. 493.

BACILLUS PARVUS OVATUS. 339

into the anterior chamber of the eye, with a piece of the
growth, or with a portion of an affected organ, they die
on an average after about eight days ; at the seat of inocu-
lation necrotic caseous processes are found, and in the
lungs there are deposits surrounded by hsemorrhagic
pneumonia, or accompanied by necrosis of the whole of
the affected portion of the lung ; there are also deposits
in the heart. Where these deposits have reached the
surface of the organs they cause exudation on the serous
membranes. The alterations are chiefly limited to the
lungs and heart, and it is only seldom that nodules are
also found in the abdominal organs. In all these
morbid products the same thin bacilli were constantly
present. — White mice die after inoculation in six days ; On mice.
at the seat of inoculation there are greenish-yellow
masses infiltrating the muscular tissue of the back over
a large area, extending deeply into the muscles of the
thigh, and ultimately reaching the peritoneum. In
sections of the tissues which are altered in this way,
long bundles of these bacilli are seen.

Bacillus parvus ovatus (Loeffler).

In a pig which had died of a disease resembling Bacilli of
erysipelas, Loeffler * found on microscopical examination erysipelas of
of the oedematous skin, and also of the liver and kidneys, 8wine-
large numbers of small ovoid bacteria, sometimes re-
calling in form the bacilli of rabbit septicaemia, more
especially in those forms which are undergoing division, Microscopical
but distinguished from these organisms by the fact that characters-
the latter are almost twice as large. In sections the
organisms are best demonstrated by staining with
alkaline methylene blue, and subsequent treatment
with 1£ per cent, of acetic acid ; in the skin they are
arranged in rows following the bundles of the con-
nective tissue. They grow readily in various nutrient Cultivations.
media, in rabbit broth and blood serum; in nutrient
jelly they develop somewhat better at the point of
entrance of the puncture than along the needle track,

* Arleiten a. d.Kaiserl Ges. AmL, vol. i., 1885, p. 51.

340

BACILLUS PATHOGENIC IN ANIMALS.

and around the point of entrance they form a greyish-
Experiments white wall, presenting a dry appearance. — After sub-
on animals. . , . *

cutaneous inoculation, mice die in about 24 hours, and

show on post-mortem examination oedema of the sub-
cutaneous cellular tissue, swelling of the spleen, patchy
redness in the lungs, and the same bacteria in all the
organs. Rabbits also die quickly, and present the same
post-mortem appearances as animals which have died of
rabbit septicaemia. Guinea-pigs die after 1 to 3 days,
and show extensive sero-sanguineous oedema of the sub-
cutaneous tissue, and of the muscles. Fowls, pigeons,
and rats proved insusceptible ; on the other hand, in a
pig the same disease, terminating fatally in 2 days,
was produced as that which had formed the starting
point of the investigation, the disease being charac-
terised by enormous oedema of the skin, bluish-red
colouration of the abdominal wall, and hypersemia of
the gastric mucous membrane, but without, alteration in
the rest of the intestine or the mesenteric glands, and
being thus distinguished from true swine erysipelas.

Bacillus tetani (?).

Tetanus
bacilli.

In the Gottingen Hygienic Laboratory, Nicolaier made
the observation that when garden earth was introduced
under the skin of mice and rabbits, these animals fre-
quently developed a series of symptoms which may be
shortly designated as tetanic. For the peculiar bacilli
found in the pus in these animals the name "tetanus
bacilli " may for the present be retained, although it is
doubtful whether these organisms are to be looked on as
Distribution the specific exciting agents of that disease. — In all, over
in the soil. 3Q different km(js Of earth from fields, gardens, and
streets were investigated; the animals frequently de-
veloped malignant oedema after inoculation, and died of
this disease in from 24 to 36 hours ; at times kinds
of earth were found, the inoculation of which caused
sometimes malignant oedema and sometimes tetanus ;
some kinds of earth, particularly earth taken from the
deeper layers, from the soil in forests, &c., had no hurt-

BACILLUS TETANI. 341

ful action ; a larger proportion, more than half of the
specimens investigated, caused always, or almost always,
tetanus. In the case of mice about as much as lay on
the point of a pen-knife, in the case of rabbits four or five
times this quantity, was introduced into a small pocket
in the skin, made on the back or thigh ; in rabbits the
wound was closed by one or two stitches.

After an incubation period of 1^ to 2J days the Course of the
earliest symptoms of the disease appear, consisting in 1
slight abduction and stretching of the hinder extremity
which is nearest the seat of inoculation, the limb soon
becoming completely stiff. In the course of a few
hours the hinder extremity on the other side is similarly
aifected, and then follow the anterior extremities. Ulti-
mately the animals become quite helpless, and generally
lie on their backs, while intermittent spontaneous con-
tractions of the extensor muscles of the neck and back
occur, in which the head is bent backwards, and the
posterior part of the body is raised from the surface on
which it is resting, the body thus describing a convex
line. These attacks can, however, be set up artificially,
and may even be caused by knocking the table, or by a
slight touch. Breathing is difficult in this stage, the
pauses become constantly longer, and finally respiration
ceases, and death occurs. In the case of rabbits well
developed trismus can be observed. Mice die on an
average at the end of 3 days ; rabbits, in whom the in-
cubation period usually lasts from 3 to 5 days, die
from the 5th to the 7th day after inoculation ; guinea-
pigs are also susceptible ; dogs, on the other hand, are
completely immune.

On post-mortem examination of animals which have Post-mortem
died with these symptoms, a relatively small amount of aPPearances-
pus of a peculiar musty disagreeable odour is found at
the seat of inoculation. Besides this, however, no im-
portant or constant pathological alteration is noticeable
in any organ, in the trunks of the nerves, or in the
spinal cord. Microscopical examination of the blood
and internal organs was also almost entirely without
result ; but in the pus at the seat of inoculation fine

•342

BACILLUS PATHOGENIC IN ANIMALS.

Morphological
characters of
the bacilli.

Experiments
with sterilised
earth.

Inoculation
from animal
to animal.

Cultivations.

bacilli were constantly present which were somewhat
longer, but scarcely thicker than the bacilli of mouse septi-
caemia, which form at times threads, and at times irre-
gular groups, and which show a characteristic mode of
spore formation. In the first place they become more
or less equally thickened, then one end swells more
markedly, finally an oval refracting spore with sharp
outlines is formed at this end, while the rest of the bacil-
lus remains as a thin thread, three or four times thinner
than the spores. Numerous free spores are also usually
present in the preparations. The same bacilli were found
not only in the pus, where they were always mixed with
other species, but also in the immediate neighbourhood
of the seat of inoculation, and in the pyogenic membrane..

These bacilli could not be directly demonstrated in
the earth. That, however, micro-organisms were the
cause of the infective properties of the specimens of
earth was evident from the fact that the same specimens
when heated to 190° C. were completely without effect,
even when introduced in very large quantities. Further,
the disease with all its characteristic symptoms could be
transmitted from animal to animal. The pus proved to
be the most virulent material ; much smaller quantities
of pus than of the original earth were required ; a very
minute loopful of pus introduced beneath the skin was
sufficient to set up a more rapid and intense tetanus in
mice after a shorter incubation period. Under these
circumstances mice died in 24 to 36 hours, and rabbits
in 3 to 4 days.— The disease could also be set up in
healthy mice and rabbits by inoculation with the blood
and organs (liver, spleen, spinal cord) of the animals
which had died ; but this was only successful when
larger quantities of the material were employed, and
even then the result was not constant, but only occurred
in about a quarter of the cases. When it occurred,
however, the whole group of symptoms were developed,
and the case terminated fatally.

Nicolaier was able to cultivate the infective organisms
in blood serum at the body temperature, without, how-
ever, obtaining a pure cultivation. The mixture of

BACILLUS ALVEI. 343

bacteria, which developed in the depth of the blood
serum and not at the surface, proved, even when carried
through nine cultivations, to be very virulent, and when
introduced under the skin of mice and rabbits with a
little wool or with a syringe, to the amount of i to 1
drop, set up severe and fatal tetanus. He did not
succeed in purifying these cultivations by the ordinary
methods, but the growth obtained consisted chiefly of
the fine bacilli above described with terminal spores ;
the virulent organisms were typical anaerobes, and could
not be cultivated at all on gelatine or agar plates. In
order to obtain a pure cultivation of these bacilli it was
necessary to employ entirely new methods, in some ways
more complicated, and with regard to which a report will
be shortly published in the Zeitschriftfiir Hygiene.

Carle and Rattone have recently excised the seat of Transmission
infection shortly after death from a patient who had tetanusTo
died of tetanus, and they injected an emulsion made ammals-
from the tissue into the dorsal muscles or into the
spinal canal of rabbits ; 11 out of 12 animals became
uifected with typical tetanus after two or three days'
incubation, and this disease corresponded absolutely in
its symptoms and course to that produced by Nicolaier,
and could be transmitted from animal to animal by
inoculation of portions of the sciatic nerve. Thus the
assumption becomes more probable that even in many
cases of traumatic tetanus in man the infective agents
discovered by Nicolaier are concerned in the disease.
We must, however, await further investigations on this
point.

Bacillus alvei (Watson Cheyne).

The etiology of the so-called foul brood of bees, a Bacilli of
disease in which an organism has been repeatedly sus- £^ broo<1 of
pected to be the causal agent, has been recently cleared
up in the manner which was to be expected by Watson
Cheyne and Cheshire.* The infective agents were iso-

* Frank E. Cheshire and W. Watso Cheyne Joiirn. of the Royal
Microscop. Soc., 1885, 11, March.

;44

BACILLUS PATHOGENIC IN ANIMALS.

characters.

lated by first purifying the surface of a diseased comb
containing in its interior affected larvae with sublimate
solution, and then opening the cells with heated instru-
ments; small portions of the dead and almost fluid
larvae were then employed for microscopical examination
and for cultivation ; by both methods a very characteristic
bacillus wras found alone and in large numbers.
Morphological The bacillus alvei is 3*63 p. in length, and '83 p. in
breadth ; the length of the organism in cultivations
varied between 2'54 and 5'08 /z. The ends of the bacilli
are rounded or pointed. Slow spontaneous movement
can be noticed in many bacilli.
They form very large spores, usu-
ally preceded by a swelling of the
bacillus in a spindle-shaped form ;
these spores are 2'12 /*. in length,
and 1'07 ^. in breadth, and are
thus broader than the bacillus and
occupy more than half its length.
The spores do not take up aniline
colours, but the bacilli can be
readily stained ; when the spores
are commencing to sprout, which
occurs after they have become
elongated at one pole, they again
take up the colouring matter.
Watson Cheyne has been able to
study the formation of spores, and
to follow accurately their mode of
Fig. 93.-Bacillus alvei sprouting, by setting on foot nu-
x 3000. From a cui- merous ^r0p cultivations, some

tivationm blood serum. V >

At *, we see spores (after from material containing only
bacini, and some from material
containing only spores, and after

these cultivations have been kept at the body tempera-
ture for varying lengths of time (10, 20, 40, 60 minutes,
&c.), taking off the cover glass, drying and staining it.
The series of permanent preparations so obtained, re-
placed in a more complete manner the continued obser-
vation of one and the same cultivation.

Method of
studying the
formation of
spores.

Cheshire and Watson

BACILLUS ALVEI.

345

The bacilli grew well at 20° C., on various nutrient Cultivations.
media; in gelatine plates they form at first small round
or oval discs, in which, with a low power, peculiar
markings, occasioned by the bundles of bacilli, is notic-
able. The colonies become gradually pear-shaped, and
from the pointed end of the pear prolongations begin to
shoot out into the gelatine. These prolongations can
be still better studied in stroke cultivations on gelatine
plates. In that case growth in the first place occurs

Fig. 94. — Cultivation of bacillus alvci.

(t, growth on gelatine plates X 80.

b, puncture cultivation in nutrient jelly X 4.

along the track of the needle ; but soon small lateral
projections appear, and from these bands of bacilli grow
out often in a single row, often two or three bacilli side
by side; these projections gradually curve, and form
well-marked circles; from these circles new projections
proceed ; the individual branches also anastomose with
each other. In the immediate neighbourhood of the
bacilli the gelatine becomes at the same time fluid, so
that ultimately there is a network of fine canals in the

346 BACILLUS PATHOGENIC IN ANIMALS.

gelatine. In puncture cultivations the same growth
appears at the surface, but along the track of the needle
white irregular clumps are formed, from which fairly
coarse branches radiate, often thickened and club-shaped
at the end, and varying much in direction and length.
In the older cultivations the fine branches disappear, so
that the connection between the primary and secondary
centres is apparently lost; ultimately, the gelatine
becomes gradually liquefied all around the colony.

On nutrient agar the bacilli form a whitish layer, on
potatoes they grow slowly in the form of a yellowish
deposit. They cause coagulation of milk in a few days ;
later on this coagulum becomes gradually liquefied,
while a very small amount of acid is formed. The
various cultivations have a peculiar smell, like old but
not yet ammoniacal urine.

Experiments Cheshire was able to demonstrate that foul brood
could be set up by the introduction of a pure cultivation
of these bacilli into healthy combs ; adult bees could
also be infected by feeding them with pure cultivations.
Flies also seem to be susceptible ; mice and rabbits show
no marked symptoms after subcutaneous inoculation of
small quantities ; but the experiments as to the action
of larger doses have not yet been concluded.

Bacilli of jequirity ophthalmia.

Therapeutic De Wecker recommended, in 1882, the employment
of jeqnirity of an infusion of jequirity seeds (obtained from Abrus
precatorius, a shrub which occurs in Southern Asia and
in Africa, and which has been transplanted to America,
and belongs to the family of the leguininosa) in order to
set up inflammation and suppuration of the conjunctiva
in cases of granulations and pannus, these troubles being,
as we know, frequently cured by these means. The
views of practitioners are at present divided as to the the-
rapeutic value of this substance ; it has chiefly attracted
attention from the fact that some observers have referred
the action of jequirity to specific bacilli.

The infusion employed is very dilute (J to 1 per

BACILLI OF JEQUIRITY OPHTHALMIA. 347

cent.), and is prepared by maceration of the pounded Preparation of
seeds with cold water for 24 hours, and subsequent
filtration (at the temperature of the body the infusion
obtained is much weaker). If a few drops of this infu-
sion are introduced into the eye of man or rabbits
symptoms of irritation commence even after 3 hours ;
after 16 hours all the appearances of a severe ophthalmia
are present, the conjunctiva becomes covered with a
thick, greyish-yellow, firmly adherent membrane, and it
is not till 5 or 6 days that the symptoms subside and
recovery takes place.

Sattler has found bacilli constantly present in the Sattier's
jequirity infusion, these organisms being 2*5 to 4'5 /*. bSh.1 7
in length, and '58 /*. in thickness ; they are partly at
rest, partly in active movement; they form distinct
spores, the spores in the shorter rods being formed at
the poles, and in the longer also in one or two parts of
the middle of the bacillus ; at times longer threads,
containing rows of spores, are found. The bacilli at a
later period become united together in the form of a
scum on the surface of the infusion ; they are typical
aerobes. The spores are relatively resistant, and with-
stand in the dry state heating to 110° C. for five
minutes. The bacilli can be cultivated on solidified
blood serum and on nutrient jelly, as well as in a
number of other media ; they cause liquefaction of the
gelatine. According to Sattler the cultivations set up
conjunctivitis when inoculated on the eyes of rabbits,
though to a markedly less degree than the jequirity
infusion and without the formation of membrane ob-
served when the latter is employed.

Cornil and Berlioz believe that they were able to infection of
demonstrate infective properties in the jequirity bacilli, wa?m-Tioo<k>d
these properties appearing after subcutaneous injection animals by
of infusion containing the bacilli into warm-blooded infusion,
animals, and into frogs. In the case of frogs the injec-
tion of one drop of a 2 to 4 per cent, infusion into the
dorsal lymph sac sets up a disease which ends fatally
within a few days with symptoms of increasing muscular
weakness ; on post-mortem examination we find sub-

348

BACILLUS PATHOGENIC IN ANIMALS.

Disproof of
for assuming

cutaneous oedema, ecchymoses in the intestinal mucous
membrane, and often large quantities of bloody fluid in
the peritoneal cavity. The jequirity bacilli are present in
the blood in large numbers. If such blood is injected
into another frog, the latter animal dies with the same
symptoms. In the case of mice, rabbits, guinea-pigs,
and fowls, extensive oedema occurs after subcutaneous
injection of the infusion, and severe pleuritis or peri-
tonitis, as well as infarcts in the liver and lungs after
injection into the pleural or peritoneal cavities. If the
infusion is injected directly into the veins of rabbits,
the animals die in a short time, often even after one
hour. If the infusion containing the bacilli was filtered
through a porcelain filter, the filtrate was found to be
without effect.

In spite of these apparently convincing experiments,
^ ^as> nevertheless, been most definitely demonstrated
b^ Neisser> Bordet, Widmark, Klein, Bruylants, and
ction of the Vennemann, and especially by Salomonsen and Dirckinck-
Holmfeld,* that no specific bacteria are concerned in the
action of the jequirity, but that the effect is due to the
presence of a soluble poisonous substance in the seeds.
It was shown that infusions free from bacilli prepared
with sterilised water and with the employment of the
usual precautions exerted the same effect on the eye,
and after subcutaneous injection on the body generally
of frogs and warm-blooded animals ; further, neither
microscopically nor by cultivation could bacilli be demon-
strated in the secretions of the affected eyes ; and pure
cultivations of the bacteria which occur in jequirity
infusion either produced no effect on animals, or set up,
when repeatedly applied to the eyes of rabbits, at most
a mild inflammation which could also be produced by
other bacteria not peculiar to the jequirity infusion.
More accurate experiments also demonstrated that the

* Neisser, Fortschr. de Med., Bd. 2, Nr. 3.— Bordet, Le
Lyon, 1883. These.— Widmark, Om Jequirity Oftalmien. Stockholm,
1843.— Klein, Centralbl.f. d. med. Wiss., 1884, Nr. 8.— Bruylants and
Vennemann, Bull, de VAcad. deMed. deBelg., 3 ser., Bd. 18. — Salomonsen
nnd Christmas Dirckinck-Holmfeld, Fortschr. d. Med., Bd. 2, Nr. 15
11. 19.

BACILLI OF JEQUIBITY OPHTHALMIA. 349

jequirity oplitlialmia could not be conveyed to liealtliy
eyes by pus or pieces of the membranous exudation, that
further the blood of frogs containing bacilli or the
oedematous fluid of warm-blooded animals infected with
jequirity by no means always causes infection in other
animals ; on the contrary, it was only possible to
transmit the disease in this way when the animals first
infected were inoculated with such large doses of a con-
centrated infusion that in the second transmission a
considerable portion of the original infusion was carried
over. Cornil and Berlioz, who were the first to observe
the transmission of the jequirity disease from one animal
to another, have worked with these great concentrations,
and hence have obtained an apparent reproduction of
the virus, which, however, does not take place if the
first infection is caused by smaller doses and less
concentrated material.

All these observations imply that the active agent of The action

...... -. i . . depends en

the jequirity seeds is not a virulent micro-organism, a soiubie
but a soluble poison, and, as a matter of fact, Salomonsen
and Dirckinck, and likewise Bruylants and Yennemann,
succeeded in obtaining a poisonous material of this
character in a concentrated form by extracting the
pounded seeds with glycerine. The glycerine extract
was precipitated with alcohol, the precipitate dried,
extracted with water, again precipitated, and then dis-
solved in water or glycerine. These solutions of
jequiritine had an extremely intense action, even the
quantity contained in ror,th millegramme of jequirity
seeds being sufficient to set up marked conjunctivitis in
rabbits, and the extract when injected subcutaneously
rapidly causes the death of mice and frogs. Thus it is
clear that the action of the jequirity seeds is only due
to the presence in them of a poison soluble in water
and glycerine, insoluble in alcohol, ether, benzine, and
chloroform, and completely deprived of its power by keep-
ing it for one hour at a temperature of 65° to 70° C.

Against the explanation of all the jequirity symptoms
as the result of the action of an unorganised virus, we
have only the observation made by Cornil and Berlioz

350

BACILLUS PATHOGENIC IN ANIMALS.

Length of life
of various
kinds of
bacteria when
injected into
living frogs,
at the same
time that
jequiritine is
introduced.

that numerous bacilli are constantly present in the
blood of the infected frogs, as well as in the pathological
secretions of warm-blooded animals. Salomonsen,
however, was able to demonstrate that we had not here
to do with the so-called jequirity bacilli, and that the
species of bacteria found in the blood may be varied at
will, according as one or other species is intentionally
allowed to develop in the jequirity infusion. Salomonsen
succeeded in obtaining multiplication of bacillus pro-
digiosus of the bacilli of blue milk, &c., in the blood of
frogs in the same manner as of the bacilli ordinarily
present in jequirity infusion. The reason of this
striking preservation and multiplication of bacteria in
the interior of the body must be sought for in the action
of the jequiritine, for it is only when this substance is
at the same time introduced in sufficient amount into
the animals that this multiplication of bacteria in the
blood takes place.

Whether the so-called jequirity bacilli are a separate
species of bacteria, or whether they are identical with some
other well-known saprophyte, perhaps with one of the so-
called hay bacilli, cannot as yet be determined from the
statements which have been made with regard to their
mode of growth and their morphological characters.

Bacilli causing erysipelas in the ear of rabbits. — In sections
from an erysipelas of the ear which occurred in a rabbit after
injection of softened fseces of mice, Koch found large numbers
of thin bacilli, 3 /x. in length, and '3 p.. in thickness, they also
formed threads up to 10 p. in length. No experiments were
made at that time (1878) as to the infective character and
mode of growth of the bacilli.

Bacillar necrosis of the liver (Ebertli). — This disease was
only met with on one occasion accidentally in a guinea-pig.
In the liver and spleen small greyish-yellow firm nodules
were found ; the lower portion of the liver was for the most
part of a gelatinous appearance, and in a state of complete
necrosis. In the necrotic tissue there were innumerable
bacilli which stained by Gram's method, were rounded at the
ends, and of an elongated egg-shape ; they often showed the
presence of spores, either at their ends or in the middle.

BACILLI OF JEQUIRITY OPHTHALMIA. 351

tisually one, but at times two in number, and the bacilli con-
taining the spores were swollen in the form of a spindle or
whetstone. Experiments on rabbits were unsuccessful.

C. BACILLI WHICH HAVE NO KNOWN SPECIFIC
PATHOGENIC PROPERTIES.

In the course of the last few years a very large
number of different kinds of saprophytic bacilli have
been discovered, of which some have been shown to be
without any pathogenic action on the higher animals,
while with regard to others the absence of pathogenic
properties has not yet been tested, or has not yet been
demonstrated with certainty. Hence the possibility must
be kept in mind that in future many of the bacteria
grouped together under this heading will subsequently
be included in one of the preceding groups when their
characters have been subjected to more accurate study.

Among the saprophytic bacilli we know some which Classification
attract attention at once by the fact that they produce ph
pigment ; others set up fermentation in mixtures con-
taining carbo-hydrates ; others are able to split up
albumen, and thus take part in the process of putrefac-
tion ; with regard to others, again, no marked action
on the substratum has as yet been observed. In the
following description certain groups have been formed
in accordance with the above facts, but these are only
temporary, and are employed to simplify their study.
A number of bacilli belong to several of these divisions,
on account of the multiplicity of their functions — pro-
duction of pigment, along with simultaneous decompo-
sition of albumen or sugar — and in the case of others a
similar multiplicity of properties will probably be found.
Hence this classification is more or less arbitrary, and
it must be left to the judgment of the individual in
which group such bacteria should be placed.

352 BACILLI OF NO KNOWN PATHOGENIC PROPERTIES.

To the bacilli which produce colouring matter
belong : —

Bacillus prodigiosus.
(Micrococcus prodigious, monas prodigiosa.)

Tliese are elliptical cells, about 1 p. in their greatest
diameter, distinctly rod- shaped before division, and at
times forming pseudo-threads. When the multiplica-
tion is rapid the short egg-shaped cells predominate ;
but their contour is seen under a high power to present
the form of an oblong with rounded ends, and not that of
a circle or ellipse. This circumstance, taken in con-
junction with the observation that when they grow
slowly, distinct rods and threads appear, renders the
previous designation of these organisms as micrococcus
no longer tenable.

Cultiva'.io Bacillus prodigiosus grows very rapidly in nutrient

jelly. In plates kept at 20° to 22° C., the deeply lying
colonies are evident after 20 hours as light grey points,
the superficial ones as light grey discs of about 1 mm.
in diameter, which are somewhat depressed and sur-
rounded by an area of liquefied, but perfectly clear,
gelatine, about 2 mm. in diameter. Under a low power
the deep colonies are seen to be round or oval with
sharp outlines, of a light reddish-brown colour, clear
and transparent at their margin. The superficial
colonies present an irregular rough outline, a granular
surface, and a light greyish-brown colour in their
middle, darker towards the periphery. — The liquefac-
tion of the gelatine goes on so rapidly that after a few
hours the whole material on the plate is fluid ; this fluid,
as well as filter paper impregnated with it, gradually
assumes a bright red colour; before the gelatine is com-
pletely liquefied, the colonies themselves show only very
little of the red coloration. As the gelatine plates of
the bacillus prodigiosus require great attention in order
that they may be examined before they have become
completely liquid, it is on the whole better to employ
agar. The agar is not liquefied, and on this material

BACILLUS PRODIGIOSUS. 353

the colonies, which are afc first white, may be allowed to
grow till their surface presents a distinct red colour.
In puncture cultivations in gelatine there is rapid lique-
faction and formation of a reddish deposit ; in punc-
ture cultivations in agar, colourless colonies develop
sparingly along the track of the needle, while on the
surface the growth extends towards the margin of the
material, and gradually assumes a deep red colour.

Bacillus prodigiosus grows very well on potatoes ; on
this material an intensely blood-red, moist layer is formed,
growing with a luxuriance and a production of a bright
colour not found in the case of any other bacterium.
When the cultivation has been kept for some time, the
surface of the red deposit presents a greenish shimmer,
similar to the appearance of crystals of fuchsine. — Growth
also occurs on a great variety of other vegetable sub-
strata, it also takes place in milk, and in the latter
material the oil globules contain the red colouring matter
in solution.

The bacilli themselves are colourless. The pigment Characters df
is insoluble in water, but soluble in alcohol ; its solu- e pl?m<
tion shows a characteristic absorption band both in the
green and in the blue portions of the spectrum. By the
addition of acid the colour changes to a carmine red, and
then to violet; when an alkali is added it becomes yellow.
The colouring matter is only formed when the colonies
of fungi are in contact with free oxygen. Hence the more
deeply seated colonies, and those which develop along the
track of the needle in puncture cultivations, are colour-
less.— Not only do these bacilli produce pigment, but simultaneous
they also set up marked decomposition of albuminous jj| th?sub-tl0n
media, this change being characterised by the produc- stratum,
tion of a smell resembling that of trimethylamine, as
well as by the alkaline reaction of the gases which are
formed; this change has not as yet, however, been
accurately analysed. — Bacillus prodigiosus appears not Distribution,
uncommonly as a spontaneous infection of articles of
food; the phenomena which were formerly repeatedly
observed of the so-called bleeding bread and the bleed-
ing host were probably caused by it ; in fact it occurs at

23

354 BACILLI OF NO KNOWN PATHOGENIC PROPERTIES.

limes in an almost epidemic manner, as was the case in
1843 in Paris, where it grew more especially in the bread
obtained from the military bakehouses. It does not
set up any symptoms in the bodies of warm-blooded
animals, even when it is injected into the blood in large
quantities.

Comparison
with bacillus
prodigioeus :
higher
optimum of
temperature.

Colour more
like that of
red wax.

Toxic action
on animals.

Bacillus indicus ruler (Koch).

This organism was isolated by Koch from the contents
of the stomach of a monkey in India; it produces a
colouring matter similar to that of bacillus prodigiosus.
The organism has the form of fine very short bacilli,
with rounded ends. In gelatine plates the deeply placed
colonies show under a low power even after 20 hours a
golden yellow colour and a wavy outline ; the superficial
colonies liquefy the gelatine, and form a funnel-shaped
depression, which very soon disappears on account of
the rapidly spreading liquefaction. The liquefied gela-
tine has a distinctly red colour. The optimum of
temperature is higher in the case of bacillus indicus
than in the case of bacillus prodigiosus ; while the latter
grows best at about 25° C., and as the temperature is
increased gradually shows less growth, the bacillus
indicus flourishes best at about 35° C. ; hence luxuriant
cultivations can be obtained on agar, on which it forms
deposits at first of a white colour, but soon assuming a
red hue. On potatoes an intensely red layer is formed,
the colour of which is more of a wax-red colour, while
the colour of the bacillus prodigiosus is darker, with a
slight tendency to violet.

Another important distinction between these two
bacilli is that the bacillus indicus is not without effect
on animals, but, on the contrary, rapidly kills them
when it is injected directly into the blood in large
quantities. Rabbits die within 3 to 20 hours, violent
diarrhoea setting in a short time after the injection ; on
post-mortem examination we find the appearances of a
severe gastro-enteritis, at times accompanied with exten-
sive ulceration of the intestinal mucous membrane.

BACILLUS PYOCYANEUS. 355

Bacillus nibcr (Frank).

These are actively moving rods, occurring singly or
united in twos or fours ; in some of these rods there are
two to four highly refracting granules (spores). The
organisms produce, when grown on boiled rice, a red
colour resembling that of red lead or sealing-wax.
Nothing further is as yet known regarding this organ-
ism.

Bacillus pyocyaneus.
(Bacterium aeruginosum, Organism of greenish-blue pun.)

It has been known for a long time that the greenish-
blue colour which sometimes appears in the dressings
on suppurating wounds is occasioned by micro-organisms.
More or less pure cultivations have also been made by
numerous investigators, and most recently by Gessard
and Charrin ; but nevertheless the majority of observers
do not seem to have obtained the organism quite pure,
for they have described it usually
as a round or oval micrococcus.
The organism can be readily
isolated by the aid of gelatine $xy &

plates. It is a thin fine bacillus, Fig. 95.— Baoim f f Morphological
of varying length, the average ^emah-blue Pu« characters,
length being about the same as

that of bacillus murisepticus, the thickness somewhat
greater. Chains of two or three bacilli are observed,
but usually they form irregular masses, united together
by a tenacious zoogla3a ; spore-bearing bacilli are also
not uncommon, and in that case they are usually some-
what thickened. — On gelatine plates the colonies form, Cultivations.
after 24 hours, whitish opaque patches, which under a
low power show a round, but not sharp outline, of a
yellowish colour, and with radiating markings ; the whole
of the gelatine presents a greenish shiny appearance.
Twenty-four hours later the deep colonies have a grey
centre, with a dark brownish-yellow zone at the outer-
most border, from which delicate radially arranged threads

356 BACILLI OF NO KNOWN PATHOGENIC PROPERTIES.

pass out; the zones gradually spread, and the circle
of fine rays constantly becomes greater. In the super-
ficial colonies the grey centre, and the surrounding narrow
darker zone are enclosed in one which is much broader,
finely granular, yellow, and highly refracting, and,
towards the outer part, gradually more and more colour-
less, with indistinct outlines ; and from the margin of this
zone fine, radially arranged, and somewhat convoluted
lines run into the gelatine. The gelatine is at the same
time liquefied, so that the original colonies soon sink
below the surface of the material. — In puncture cultiva-
tions the growth is less characteristic ; complete liquefac-
tion of the gelatine soon occurs with the production of a
greenish colour, which becomes more yellow as the
cultivations get older. On agar material a whitish
deposit is formed at the surface, and the substratum
assumes a bright green colour. On potatoes the organ-
isms form a yellowish-brown moist layer; if this layer
is completely removed, and the exposed portion is acted
on for a long time by the air, or for a short time by the
vapour of ammonia, the surface of the potato becomes
greenish. — In sterilised milk the bacilli in the first place
cause the formation of greenish-yellow flakes on the
surface, they then lead to precipitation of the casein,
which they peptonise gradually, with the simultaneous
appearance of ammonia.

Colouring The colouring matter produced by the bacilli has been

investigated by Fordos and Gessard, and has been
called pyocyanin. It is soluble in chloroform, and
crystallises from the pure solution in the form of long
blue needles ; acids convert the blue into red, reduc-
ing substances into yellow. It is apparently closely
related to the ptomaines because it is precipitated by
chloride of platinum, phosphoric molybdic acid, &c. —
This organism does not cause suppuration, and is
apparently only a harmless inhabitant of wounds.

BACILLUS ERYTHROSPORUS. 357

Bacillus fluorescens putidus.
This organism occurs frequently in putrefying

. , , i stinking

materials ; it imparts to the latter a greenish hue, and bacillus,
produces at the same time a smell resembling that of
trimethylamine ; it does not liquefy the gelatine.* — The
organism presents the form of small, short, very actively
moving bacilli, with rounded ends. They form in the
deeper parts of the gelatine plates very small dark
colonies (under a low power), which grow better at the
surface, and then present the appearance of round discs,
with sharp wavy outlines ; in the centre the remains of
the deep-seated colonies appear as a dark speck ; the
surrounding mass is yellow, light grey, and finely
granular towards the margin. On the third day the
colonies have extended markedly on the surface, they
present an irregular outline and have a greenish shimmer,
in fact the whole plate has a greenish shimmer ; at the
same time there is a strong smell resembling that of
herring brine. In puncture cultivations a faint grey or
milky muddiness develops along the track of the needle,
this muddiness extending much more markedly on the
surface ; from the third day onwards there appears a
greenish coloration of the gelatine gradually extending
from above downwards. On potatoes the organisms
grow rapidly in the form of a brownish, or at the surface
more greyish, thin layer.

Bacill us erythrosporus .

This organism was formerly observed by Eidam, and Fluorescing
afterwards by Cohn and Miflet, in meat infusion, in reddish* *
putrefying albuminous fluids, &c., and was obtained sP°res<
from the air.t Since that time it has been often
observed in a great variety of putrefying fluids as well
as in drinking water. It presents the form of thin
mobile bacilli with abruptly rounded ends, often forming
short threads. At the ordinary temperature two to eight

* Gottinger hygienisches Institut.

f Cohn's Beitrdge zur Biologic der Pflanzen, vol. iii., part 1, p. 128.

358 BACILLI OF NO KNOWN PATHOGENIC PROPERTIES.

oval spores, arranged like a string of beads, appear in eacli
rod ; these spores project in part beyond the contour of
the bacillus, and, when brought into accurate focus,
show a distinct dirty red colour. The spores also retain
the red colour after staining the rods, for example, with
methylene blue. — The bacilli form whitish colonies on
gelatine which are circular under a low power, with
irregular but sharp outlines. The opaque brownish
centre is surrounded b}7 a greenish-yellow lighter mar-
ginal zone ; the surface shows faintly marked radiating
lines. As the colonies spread on the surface of the
gelatine their border becomes very irregular and dentate,
and from the dark centre radiating lines, now much
more distinct, run in a wavy manner towards the peri-
phery, implying wrinkling of the layer. At the same
time a greenish-yellow fluorescing colour appears around
each colony. — In puncture cultivations a somewhat
plentiful growth occurs along the whole canal, chiefly,
however, at the surface ; the whole of the gelatine
gradually assumes a greenish colour by transmitted
light, and yellowish by reflected light, this colour
spreading from above. — On potatoes a slight deposit is
formed, at first of a reddish hue, and later of a brownish
nut colour.

Bacillus JiiLoresccns liquefaciens.

Liquefying This organism occurs extremely frequently in a great
vai'iety of putrefying substrata, in water, &c. — It pre-
sents the form of short mobile bacilli arranged in pairs,
and constricted in the middle ; spore formation has not
been seen. — On gelatine plates it forms whitish points
which spread at the surface in the form of fairly large
colonies, attaining even as much as 3 mm. in diameter ;
at the same time a ring-shaped liquefied zone appears
around each colony. Under a low power irregularly
circular, and later sinuate colonies with sharp outlines
are observed ; the centre is dark brown, finely granular,
and surrounded by a yellow finely granular zone, which
becomes whitish-grey and transparent towards the

BACILLUS LUTEUS. 359

margin. The whole gelatine gradually assumes a
greenish colour. — In puncture cultivations a whitish
layer is formed along the track of the needle, and at the
point of entrance of the needle a small funnel-shaped
depression appears, containing at the lower part liquefied
gelatine, and at the upper part air. The liquefaction
gradually spreads until it reaches the wall of the glass,
and slowly extends downwards ; at the bottom of this
liquefied material, a thick, whitish deposit is formed.
Beneath the area of liquefaction the gelatine has a
greenish-yellow fluorescing appearance > the liquefied
mass does not show the play of colours so markedly. — On
potatoes a brownish deposit is formed, which, however,
is not characteristic.

Among the bacilli which produce greenish colouring matter Greenish
should probably be placed the organism described by Engel- coloured
maim as bacterium clilorinum, and by van Tieghem as ba-c-
terinm viride and bacillus virens, in which the substance of
the cell itself presents a greenish colour. The species in-
vestigated by Engelmann was an oval, very mobile rod, 2 to 8
/*. in length; the bacilli investigated by van Tieghem were
non-motile. It is, however, riot impossible that in all three
cases these authors had to do with fission algae ; we must
await a more accurate description.

Bacillus luteus.*

This is a short bacillus of medium thickness, and Yellow
apparently non-motile. It forms in gelatine plates
deeply placed colonies, of a lentil or whetstone form (as
seen under a low power), at times with irregular out-
lines, at times with sharp smooth contour, and of a
brown colour. The superficial colonies are 10 to 20
times larger, they measure 2 to 3 mm. in diameter, and
appear round, often irregular in outline, of a light brown
colour, and with a whitish, clear, transparent margin.
Macroscopically, the colonies are yellow and opaque ; in
puncture cultivations a yellow growth is formed both
along the track of the needle and also on the surface,

* Gottinger hyg. Institut.

360 BACILLI OF NO KNOWN PATHOGENIC PROPERTIES.

but without liquefaction and without staining of the
gelatine. — It occurs very frequently as an impurity on
plate cultivations, &c.

Brown
bacillus.

Bacillus fuscus.*
(Bacterium brunneum.)

This organism was obtained by Schroter from a
putrefying infusion of maize in the form of mobile rods,
which produced a brown colouring matter, and which
he described under the name of bacterium brunneum.
These organisms are probably identical with a bacillus
which also furnishes a brown colour, and which occurred
in some rare cases as accidental impurities in Gottingen.
— These organisms present the form of long narrow rods
with abrupt ends, and irregular and in parts slightly
projecting outlines. They form on gelatine plates
fairly quickly growing knob -like colonies of a brownish
colour ; under a low power we see in the centre
irregular brownish-black balls which are surrounded by
a highly refracting border. In puncture cultivations
their growth is not very characteristic ; on the surface
they form a fairly thick, and at a later period a wrinkled
brownish-red deposit around the point of entrance of the
needle.

Bacillus of
yellow milk.

Bacillus synxanthus.
(Bacterium synxanthum, Ehrenberg.)

These are actively moving rods which were observed
by Schroter t in milk which had accidentally become
yellow; by inoculating the organism on normal boiled
milk, its colour became citron-yellow. The colouring
matter was soluble in water, insoluble in alcohol and
ether ; acids decolourised it, alkalies again brought back
the colour. Nothing further is known as regards the
micro-organisms which produce these effects.

* Gottinger hyg. Institut.

f Cohn's Beitr. zur Biol. d. Pflanzen, vol. i., part 2, p. 120.

BACILLUS CYANOGENUS. 361

Bacillus janthinus (Zopf).
(Bacterium janthimun, violet bacillus.)

Zopf observed on pieces of swine's bladder, which Violet
were floating on water containing fungi, violet patches
consisting of longer and shorter mobile rods, ultimately
breaking up into short segments. — These bacilli are
perhaps the same as those found by Hueppe, and at a
later period on several occasions in the laboratory at
Gottingen, and which produce an intensely bluish-violet
pigment. These bacilli when grown on gelatine form at
first milk-white layers, which gradually assume a violet
colour at the margins, and in the neighbourhood of which
the gelatine acquires the same tint ; it is not till after
several days that the whole surface of the colonies acquires
an intense violet hue. In puncture cultivations the
violet growth only develops at the surface ; on potatoes
a deep violet layer is produced. In sterilised milk the
bacilli produce patches on the cream, at first intense
sky-blue in colour, but gradually becoming blackish-
blue ; at the same time the casein is precipitated and
then peptonised, the fluid acquiring an alkaline reaction,
and ammonia being formed (Hueppe).

Bacillus cyanogenvs.
(Bacterium syncyanum, Bacillus of blue milk.)

The occurrence of blue milk is frequently observed in Bacillus of
many places ; at, times its occurrence varies, like that of bluemilk-
epidemics, in accordance with local and seasonal influences.
Great moisture of the atmosphere has generally been
regarded as a favouring factor, while temperature, light,
&c., do not apparently exercise any marked influence.

Fuchs in 1841 asserted that a vibrio was the agent Former
which produces the blue colour, and he demonstrated
that this production of colour could be set up in good
milk ; these investigations were confirmed and extended
by Haubner, Hermbstadt, Hosier, and others, and recently
more especially by Neelsen and Hueppe. Neelsen has

oG2 BACILLI OF NO KNOWN PATHOGENIC PEOPEETIES.

described bacilli which undergo an extensive change of
form, and which always ultimately break up into cocci ;
but these observations evidently depended on contamina-
tion of the cultivations with other forms of bacteria, such
u contamination being almost unavoidable with the
methods of cultivation employed at that time. It is now
quite easy by the help of gelatine plates to isolate the
characteristic bacteria from any specimen of blue milk.

Tbe bacilli move slowlv> fcney llaYe an average length
of about 2 /*., but vary between 1'4 and 4 /*. ; their
thickness is about '4 ^., and in stained preparations it
also shows slight variations. In preparations from milk
their size is more uniform. At the ordinary temperature
spore formation occurs in gelatine, in milk, &c.; the spores
are formed at one end, so that the spore and the remains
of the bacillus often present a club form. In unsuitable
nutrient solutions, for example
in slightly acid solutions of tar-
°f ammonia, or Cohn's nu-
trient solution to which nitrate

Fig. 96.- Bacilli of blue ,, , . ,, , . , ,.

milk x 700. of potasn is added, involution

At a we see spore-bearing forms often appear, the bacilli

bacilli, and others with •> . 111 n • ai

unstained portions of being club-shaped or spmdle-
plasma- shaped, or presenting the form

of long threads, with spherical dilatations at intervals.
Cultivations. In gelatine plates small greyish-white points appeal-
after two days, and these spread out on the surface in
the form of moist drops, 1 to 2 mm. in breadth. The
whole plate assumes a steel greyish-blue colour, so that
the white colonies become gradually more distinct.
Under low powers the smallest deeply-lying colonies
present the form of circular discs with black centre and
brownish granular margin, and with a sharp black
outline. The superficial colonies show a blackish-
brown centre, around this a greyish-brown area, and
further outwards a narrow, yellowish, finely granular
zone with sharp outline. — In puncture cultivations a
whitish deposit is formed especially on the surface, and
from this growth a dark steel blue staining of the gelatine
spreads downwards. — On potatoes a yellowish moist

BACILLUS ACIDI LACTICI. 863

deposit is formed, and in the neighbourhood the sub-
stance of the potato assumes a deep greyish-blue colour.
At times the gelatine has a more greenish shade ; distinct
green colour is produced, for example, in solutions of tar-
trate of ammonia, of leucine, asparagine, &c., but this
green pigment only represents a lower stage of oxidation
of the blue, and can be transformed into the blue by oxi-
dising agents. — When inoculated in sterilised milk the
bacilli cause no coagulation and no acidity, but gradually
produce a slightly alkaline reaction ; further, a slate-grey
colour, which, however, on the addition of acid becomes
an intense blue, appears in the first instance in the layer
of cream, and then spreads clown wards through the
whole fluid. In milk which has not been sterilised, and Character of
in which the lactic acid bacilli are growing at the same
time, the colour is sky-blue from the first. — In milk the
colouring matter seems to be formed at the expense of
the casein, while the milk sugar remains unaltered ; the
bacilli, however, are able to build up the colouring matter
synthetically in fluids which only contain lactate of
ammonia, or tartrate of ammonia without any albumen.
The optimum of temperature for the production of the
pigment is from 15° to 18° C. ; above 25° C. the pigment
production is delayed ; at 37° C. no colouration of the
nutrient solution occurs. The pigment is not an aniline
dye, but more accurate investigations as to its properties
and its nature are still wanting. — The bacilli and the
milk in which they are growing have proved to be quite
harmless to animals, even when injected into the veins.

Among the bacilli which cause fermentation of carbo-
hydrates, the following must be mentioned : —

Bacillus acidi lactici.
(Lactic acid bacteria.)

The phenomenon which has been for a long time well
known, that when milk is kept for some time the milk
sugar becomes transformed into lactic acid, and, as a

364 BACILLI WHICH CAUSE FERMENTATION.

result, the casein coagulates, was first ascribed by Pasteur
to the action of definite micro-organisms. Nevertheless,
Lister seems to have been the first to obtain a pure
cultivation of lactic acid bacteria by the employment of
Formation of the so-called dilution method. — As the result of the

lactic acid by ..... f .

various kinds investigations oi the last tew years the views advocated

>f bacteria, ^y Pasteur and Lister have in so far undergone an
important modification in that, according to more recent
experience, the power of forming lactic acid from carbo-
hydrates, and more especially from the milk sugar of the
milk, evidently appertains to a large number of species of
bacteria, and differences among these species exist mainly
as regards the quantitative production by each kind.
For example, this property is possessed by all the
pyogenic organisms, more especially by the staphylo-
cocci, then by the bacillus oxytocus perniciosus ; the
bacterium coli commune, and bacterium lactis aerogenes ;
further, by a species of bacteria isolated by Miller from
carious teeth ; lastly, according to Hueppe's experience,
by bacillus prodigiosus, and by a species of coccus
isolated from the secretion of the mouth, and growing
in the form of flat white knobs. Undoubtedly the
number of organisms which are capable of causing lactic
acid fermentation is not exhausted by these 15 species.

Nevertheless, one definite organism seems to have the
right to the designation " lactic acid bacterium," because
it is evidently by far most frequently the cause of the
spontaneous clotting of milk, and because also it is
marked out from the other bacteria which have a similar
action by its wide distribution, and by the intensity of

Lactic acid its effect. This lactic acid bacillus has been accurately
described by Hueppe, and is probably identical with
that observed by Lister and Pasteur.

Morphological This bacillus forms short, thick cells, which are at
least half as long again as broad, and are usually united
in pairs, seldom in fours. Under too low a power the
individual cells may present the appearance of oval cocci,
but when more highly magnified we see distinctly that
the outlines are parallel, and that the ends are slightly
narrowed in the longitudinal direction. The average

BACILLUS ACIDI LACTICI. 365

length of these rods is, according to Hueppe, 1 to 1'7 ^.,
their breadth *3 to "4 /*., but rods as long as 2*8 p. also
occur. The bacilli have no spontaneous movement. In
solutions of sugar they show distinct spores, which are
also formed in milk, but are much more difficult to
recognise in that medium. The spores appear as
refracting globules at the ends of ^

the bacilli ; if two bacilli are united ***'£{ §: r ^
together the spores often appear at Fig. 97.— Lactic acid
the ends furthest removed from bacillus x 700.

i . . ' , „, . . Cover glass preparation

each other, but often also at the from a fresh cultiva-
adjacent ends. Bacilli containing tlon*
these spores are not killed when boiled for a short time. —
The bacilli grow readily on various soils. In gelatine Cultivations.
plates they form on the second day whitish colonies,
which under a low power, and so long as they are deeply
situated, present the form of circular discs, uniformly
dark, and with sharp black outlines ; those which occur
on the surface are surrounded by a somewhat clearer
marginal zone. In puncture cultivations a deposit,
which is at first delicate, and later somewhat denser, and
which forms at parts discrete spheres, appears along the
whole track of the needle. In stroke cultivations the in-
dividual colonies, which are at first circular, run together
and form a narrow white stripe, with irregular borders.

Lactic acid fermentation can be set up with pure cul- Conditions cf
tivations of these bacilli in solutions of milk sugar, cane fermentation,
sugar, mannite, and dextrose. In addition to lactic
acid, carbonic acid is also always formed. When more
than *8 per cent, of lactic acid is present in the ferment-
ing mixture, the progress of the fermentation is inter-
fered with, and hence when it is desired to carry the
fermentation further it is necessary to add chalk in order
to neutralise the acid.

According to Hueppe, free oxygen is necessary for the Necessity for
occurrence of the fermentation ; nevertheless, very °xyg(
small quantities are sufficient in order to permit the
formation of the amount of lactic acid necessary to
cause coagulation of the casein ; but larger quantities of
acids appear to be formed only when there is a corre-

36G

BACILLI WHICH CAUSE FERMENTATION.

Kennet-like

spondingly larger amount of oxygen present. The
optimum of temperature lies between 35° and 42° C. ;

Inoculation on at 45'4° C. fermentation ceases. — If a small portion of a
pure cultivation is introduced into milk, previously
sterilised at 100° C., the latter becomes uniformly
gelatinous in 15 to 24 hours at the body temperature.
Here and there small spaces are visible in the coagulum,
containing bubbles of carbonic acid. At a later period
the coagulum contracts somewhat, and clear serum
collects around it. The coagulum does not become
peptonised subsequently.

Dehydrating- It appears that the lactic acid bacilli dehydrate the
milk and cane sugar before they cause their fermenta-
tion. They are also able to convert starch into sugar
in the same manner as a diastatic ferment. (See under
"Ferments.")

It must be borne in mind that the casein of milk is
not only coagulated by lactic acid, but also by rennet-

by bacteria, like ferments, and that, as Duclaux first showed, a
number of bacteria are able to furnish these ferments,
and thus without the formation of lactic acid to coagu-
late the casein ; the reaction of the material is am-
photeric, that is to say, slightly acid, and slightly
alkaline. This property occurs, for example, in the
bacillus butyricus, in the so-called potato bacillus to be
described below, in sarcina lutea, in a large coccus
cultivated by Hueppe from water, and causing liquefac-
tion of the gelatine, and probably also in many other
bacteria. The same bacteria frequently exert a subse-
quent peptonising action on the coagulated casein.

Bacillus butyricus.
(Clostridiiun butyricum, Bacillus amylobactcr.)

In the case of the butyric acid fermentation we must
probably also come to the same conclusion as in that of
the lactic acid fermentation, viz., that several kinds of
bacteria can cause this fermentation of carbo-hydrates,
and this without reckoning those bacteria which form
butyric acid from other materials (for example, the

Butyric acid
bacillus.

BACILLUS BUTYRICUS (PRAZMOWSKI.) 367

bacilli of greenish-blue pus from glycerine, &c.). Pasteur, Butyric acid
Prazmowski, Fitz, and Hueppe have each described c|™ed by0"

bacilli which cause butyric fermentation, but which y-anons

bacteria.
according to the descriptions as yet given are not

the same species in each case, although some of them
have not been sufficiently accurately studied to enable
us to come to a conclusion as to their identity. Accord-
ing to investigations in the author's laboratory the
number of butyric acid bacilli is probably very con-
siderable ; but the majority of these, on account of the
fact that they are anaerobes and cannot be isolated and
cultivated pure by the ordinary methods of cultivation,
present such great difficulties in their diagnosis that
we must await further investigations in order to
obtain an accurate knowledge of these forms. In the
following description we shall take as our basis the
description of the butyric acid bacillus given by Praz-
mowski, which corresponds fairly well with that of
Pasteur and van Tieghem, but which has not been
based on pure cultivations ; secondly, we may describe
for the present as a separate species an anaerobic
bacterium, the characteristics of which have been
studied by Liborius in the author's laboratory — with
regard to its fermentative activity, accurate analyses
are wanting, but it is possibly identical in its mor-
phological and biological characters with Prazmowski's
organism ; and in the third place we must mention
the bacillus isolated by Hueppe from milk, and which
differs in an important manner from those previously
mentioned on account of its aerobic properties.

Bacillus bufyricus (PRAZMOWSKI).

This organism presents the form of rods 3 to 10 /*. l. Prazmow-
in length, and 1 /*., or somewhat less, in breadth. It acid bac jfus.
frequently forms chains, or apparently threads, which
have not undergone segmentation. It is usually
actively mobile, but at times it is at rest and forms
zooglcea. After some time the rods cease to grow in Morphological
length and increase in thickness ; the shorter rods c
increase in thickness chiefly in their middle, and

368

BACILLI WHICH CAUSE FERMENTATION.

Anaerobic
properties.

assume a spindle form ; the longer are often enlarged
at one end like a tadpole. The swollen rods may attain
a breadth of from 1*8 to 2'6/z. At the same time the
plasma becomes more highly refracting, and the mem-
brane markedly thickened. When this has taken place
spore formation commences ; the ovoid spores are 2 to
2*5 p. in length, and 1 /*. in breadth, they become free
by solution of the membrane of the mother cell. The
spores sprout in the following manner : — At one of the
pointed ends of the longish spore the double contour of
the spore membrane disappears, and the germinating
tube passes out ; the longitudinal diameter of the latter
is parallel to that of the spore. The dense spore
membrane does not shrink, and often remains attached
to the young rod for a long time.

This bacillus is a typical anaerobe; its whole vital

M

<a 0 c «>

000^

Fig. 98.— Bacillus butyricus (after Prazmowski) X 1020.

A and 5, colonies and chains of bacilli.

C, colonies with swollen, spindle-shaped, and spore -forming bacilli.

D, germination of the spores ; a to it successive stages.

functions seem to go on quite independently of the
presence of free oxygen, and, in fact, they are inter-

BACILLUS BUTYEICUS (PRAZMOWSKI). 369

t'ered with when considerable quantities of that gas are
present. The spore formation and the sprouting of the
spores appears also to occur only when oxygen is
absent. Hence it differs markedly in its physiological
characters from the bacillus subtilis, which in other
respects resembles it. Further, the spores of bacillus
butyricus do not show the same resisting power as the
spores of bacillus subtilis. The boiling temperature
continued for five minutes is sufficient to kill them.

Intense fermentation can be readily set up by the Conditions of
bacillus butyricus. In solutions containing starch, dex- e
trine, sugar, or lactates, a considerable quantity of butyric
acid is formed in the course of a few days as the result
of the action of the bacillus butyricus, carbonic acid
and hydrogen being at the same time given off. The
vessels containing the nutrient solutions in which these
fermentation experiments are made should be kept
hermetically sealed, and freed as far as possible from
air before the bacilli are introduced ; the high pressure
which the accumulated gases exert after a short time
does not at all interfere with the development of the
bacillus and the progress of the fermentation. The
same bacillus is the cause of the butyric acid fermenta-
tion which occurs in old milk, and in the ripening of
cheese. In the case of milk this fermentation com-
mences after the active growth of the lactic acid bacteria
has converted a large portion of the milk sugar into
lactic acid, either because the necessary removal of the
oxygen is accomplished by the previous development of
the aerobic lactic bacilli, or because the milk sugar is
dehydrated by the lactic bacilli and thus converted into
good fermentescible material. The best temperature for
the fermentation is between 35° and 40° C. Just as
in the lactic fermentation so here we must add chalk
to the fermenting mixture in order to prevent the dis-
turbing effect on the bacillus of the accumulation of
acid. — According to Fitz the bacilli are also able to
dissolve casein slowly, but not to cause the direct
fermentation of sterilised milk, or its coagulation,
because they are not able to break up milk sugar.

24

370

BACILLI WHICH CAUSE FERMENTATION.

Iodine reac-
tion.

Other fer-
mentative
action.

Distribution.

A property which occurs under certain circumstances,
and which is peculiar to the butyric acid bacillus, is the
power of forming a material (granulose) in the plasma,
which assumes a blue or blackish-violet colour with
iodine. This property can be most readily observed
when the bacillus is cultivated in media containing
starch; but the coloration also occurs in the absence
of starch when, instead of it, cellulose, or lactate of lime,
or glycerine is present; it seems to occur seldom in
nutrient solutions containing dextrine and sugar. Young
rods stain of a pure blue colour, older rods of a dark
violet; in some only a few transverse zones are blue,
in others the rods are continuously stained (compare also
Leptothrix, page 392 ; bacillus polymyxa, page 374 ;
bacillus Pasteurianus, page 390).

It is possible also that the bacillus butyricus has
another fermentative action, in that it is able to cause
fermentation of cellulose; according to Tappeiner,
methane, carbonic acid, and sulphuretted hydrogen, or
only hydrogen and carbonic acid are formed according
to variations in the composition of the nutrient substrata.
(See the chapter on " Fermentation.") This decomposi-
tion of cellulose has probably a certain technical im-
portance, for example in the preparation of flax, and
is perhaps also of physiological significance in the
digestion of cellulose by herbivora. (Van Tieghem
ascribes the property of destroying cellulose to a special
bacterium called bacterium amylobacter, an organism,
however, which this author stated at a later period
to be identical with the butyric acid bacillus described
by Pasteur).

Bacillus butyricus seems to be extremely widely
distributed in nature; it can be obtained from hay-dust,
from a great variety of putrefying vegetable infusions,
from sauerkraut, from old cheese, from milk which has
been kept for a long time; according to Deherain and
Maquenne* it occurs also in the earth of fields. It has
also been observed in the cells of plants which have a
milky juice. Van Tieghem was able to recognise it

* Bull. soc. chim. (2), 39.— Compt. Rend., 97.

BACILLUS BUTYRICUS LIBORIUS. 371

from its morphological peculiarities in fossil conifers of
the coal formation.

Bacillus butyricus (Liborius).

Liborius' butyric acid bacillus presents scarcely any 2. Liborius'
noticeable difference from the former in its morphological bacSus aC1
characters, more especially in its mode of spore forma-
tion. Cultivations in solid nutrient media (nutrient
agar, or nutrient gelatine, best when grape sugar is
added) only succeed when a fairly thick layer is em-
ployed, and in this case a superficial zone, about 3
cm. in breadth, usually remains free from growth;
the organism can also be cultivated in nutrient substrata
from which the oxygen has previously been expelled by
some other gas. Further, it is of importance not to
inoculate the solid gelatine by the puncture method, and
thus to form a canal for the air, but to mix the material
with liquefied gelatine. In this case whitish, but not
sharply defined colonies appear in the course of one or
two days, and after 24 hours more become surrounded
by a narrow line of liquefaction; the extent of the
liquefaction gradually becomes greater, and the whitish
mass of the colony sinks to the bottom; ultimately these
globules coalesce, and at the same time gas bubbles
usually penetrate into the upper part of the gelatine,
drive out the oxygen from it, and thus the growth and
the liquefaction gradually extend upwards. — In nutrient
agar the form of the young colonies can be better recog-
nised; and it is then seen that their outline is irregular,
and even to the naked eye shows a finely branched
appearance; under a low power the delicate ramifying
threads around the margin of the colony form a very
characteristic picture. In the test-tubes containing agar
active development of gas also occurs, so that the upper
portion appears as if it had been split. These gases
have a disagreeable smell, often recalling that of pure
butyric acid ; other gases, which probably arise from the
simultaneous decomposition of the albumen, are also
often present. A more accurate analysis of the fer-
mentative products is still wanting.

372

BACILLI WHICH CAUSE FERMENTATION.

3. Hueppe's
aerobic
butyric acid
bacillus.

Action on
milk.

Bacillus butyricus (Hueppe).

Hueppe was able to isolate large bacilli from milk which
was sterilised sufficiently to prevent the lactic fermenta-
tion, but in which the casein became precipitated later,
the reaction of the medium being at first unaltered, and
later slightly alkaline ; these organisms resembled mor-
phologically those described by Prazmowski, but were
much less sensitive to oxygen. They grew in nutrient
jelly, and led to rapid liquefaction of it, and no precautions
with regard to the removal of oxygen were necessary. —
These bacilli are unable to cause directly the fermentation
of milk sugar, and only form butyric acid when the milk
sugar has been either dehydrated by other bacteria or
when lactates are present. They also cause coagulation
of the casein like the rennet ferment, and then they split
up the casein, and produce peptone, leucine, tyrosine,
ammonia, and substances with a bitter taste. The
coagulum of casein, which is at first precipitated from
sterilised milk by the butyric acid bacilli, presents, after
about 8 days, an appearance as if its edges were being
eaten away, and it gradually disappears almost entirely.

Bacillus caucasicus.
(Dispora caucasica, the ferment of kephyr.)

Organisms of An intoxicating drink has been repeatedly obtained

kephyr. from milk by alcoholic fermentation, as for example in

the preparation of koumis from the milk of mares by

the inhabitants of the Kirghiz steppes, and also in the

preparation of kephyr from the milk of cows, as has been

done from ancient times in the Caucasian highlands.

In these cases the alcoholic fermentation appears to be

always occasioned by a torula; as, however, the milk

sugar of milk cannot undergo the alcoholic fermentation

directly, something must be added to it which is able to

transform the milk sugar into fermentescible glucose.

The course of This transformation is carried out in an energetic manner

fernSatior ^ tlie ordinary lactic acid bacteria, and thus an alcoholic

fermentation of milk may be set up by the combined use

of lactic acid bacteria and yeast cells. But the lactic

BACILLUS CAUCASICUS. 373

acid bacteria always transform at the same time a portion
of the milk sugar into lactic acid, and this leads to the
coagulation of the casein, and thus ultimately a drink
results which contains alcohol, hut which also has a very
sour taste, and in which coagulated casein, usually in
the form of finely divided flakes, is suspended. Accord-
ing to Hueppe, other bacteria are also present in the
kephyr which are able to peptonise the casein, so that we
have here a combined action of three micro-organisms.

The ferment of kephyr, which includes two or three Constituents
active fermentative agents, can be dried, preserved for a
long time, and sent from one place to another. In the
milk the kephyr granules grow and form largish fungus
masses which are composed of numerous microscopic
globules. In these globules, according to Kern and
Krannhals, three structures can be distinguished under
a high power — yeast cells, fairly long rods, and smaller
cells, which are looked on as free spores. The long rods
have been accurately described by Kern, and called Dis-
pora caucasica.

These bacilli are 3*2 to 8 /*. in length, and *8 /x. in Morphological
breadth. At one end a flagellum can sometimes be seen,
and in fresh preparations the bacilli show spontaneous
movement in the form of a slow, pendulous, and see-saw
motion. The spore formation appears to be very charac-
teristic; on each rod two terminal spherical cells are
formed, and threads containing rows of spores occur,
the spore being always so arranged that each of the cells
contained in the thread has two spores. The spores
which lie in the cells are about *8 P.

in diameter, those which are free ^^ *

attain a size of 1 /*., and those which

0 <\ n

are sprouting may swell up to about " J^ o

1*6 p.. The usual mode of sprouting " a

of the spores is that the thinner c=o

endosporium first projects out of the Fi&- 99.— Dispora]

. . L .' i-t 11 caucasica X 1000.

thicker exosporium like a small wart, (After Krannhals.) j

which gradually increases in size, and

develops in the form of a cylindrical tube. — According Cultivation

to Kern a suitable nutrient solution is formed by 5 exPeriments-

374 BACILLI WHICH CAUSE FERMENTATION.

parts of phosphate of potash, 5 parts of sulphate of
magnesia, '5 parts of chloride of calcium, 9 parts of
tartrate of ammonia, 44| parts of milk sugar, and
1,000 parts of water ; according to Krannhals they also
grow in mixtures containing extract of meat, milk sugar,
and gelatine. Investigators have, however, not as yet suc-
ceeded in making out any definite culture characteristics.
The yeast cells which are also present in the kephyr
are round or egg-shaped, 3'2 to 6*4 M- in diameter, and
occur singly and in various stages of budding ; spherical
and ovoid spores are also seen. — We must await further
investigations of these organisms, and more especially
pure cultivations, in order to obtain a clear understand-
ing of the peculiar fermentative process which takes
place in the preparation of kephyr. (See under " Fer-
mentation.")

The culture characteristics and the fermentative products
of the following bacilli which act on media rich in sugar are
imperfectly known.

Bacillus polymyxa (Clostridium polymyxa), Prazmowski. —
This organism exactly resembles bacillus butyricus in size,
shape, and mode of development, and occurs along with it.
The only difference between the two organisms is that in the
case of the bacillus polymyxa we find here and there peculiar
dilated and wavy threads without any distinct segmentation,
and these break up at a later period into shorter segments ;
it is probable that these structures are involution forms.
Further, these bacilli usually require free oxygen for their
growth and spore formation, and do not exert any fermentative
action under normal conditions ; but if the access of oxygen is
prevented they set up intense fermentation, the exact nature
of which is not known, in infusions of potato, lupin-seeds, &c.
The bacilli form a scum on the surface of nutrient solutions ;
on boiled beet-root they form gelatinous masses of large ex-
tent, and of cartilaginous consistence like those of leuconostoc
and ascococcus. — In nutrient solutions containing starch the
bacilli show a faint blue colour when treated with iodine, but
this reaction is not found when they are growing in solutions
in which starch is not present.

Bacillus dysodes (Zopf). — These are rods forming threads
which break up into short rods and cocci, and each of these
rods produces an elliptical spore. They cause peculiar f ermen-

BACILLUS PYOGENES FCETIDUS. 375

tative changes in bread, forming there fluid substances with a
disagreeable smell (similar to that of a mixture of peppermint
and turpentine oil), and the result of their growth is that the
bread becomes greasy in its interior and unfit for use. If the
yeast is washed with a half per cent, solution of hydrochloric
acid, the hurtful action of the organism seems to be prevented.
As to the production of gluconic acid, acetic acid, propionic
acid, &c., from carbo-hydrates as the result of the growth of
bacteria, see the chapter 011 " Fermentation."

Bacilli which are able to split up the albuminous Putrefactive
molecule with the development of gaseous foul-smelling
products, and thus set up putrefactive fermentation of a
more or less intense character, are apparently very
common. Among the bacteria already described, and
which chiefly act in this manner, may be mentioned
bacillus butyricus, bacillus prodigiosus, bacillus fluores-
cens putidus, bacillus fluorescens liquefaciens, and a
bacillus isolated by Miller* from the intestines, but not
as yet more accurately described, and which furnishes
sulphuretted hydrogen and ammonia; also the bacillus
ureae, to be mentioned below; all these organisms are
able to split up albumen or gelatine, with the formation
of foul-smelling products. The following may also be
mentioned as having considerable power in this respect.

Bacillus pyogenes fostidus (Passet) .

This organism was obtained by Passet from the foul- Passet'sputre-
smeliing pus of an abscess. It consists of short rods,
rounded at the ends, with slow movements, 1*45 /*. in
length, and '58 p. in breadth, and frequently arranged in
pairs or in groups. One or two unstained spots can at
times be seen in the interior of the rods ; these are pro-
bably spores. In gelatine plates white points appear
after 24 hours, which develop at the surface in the form
of greyish-white patches, extending to about 1 cm. in
diameter, and becoming confluent, thicker, and whitish
in the middle, thinner and greyish towards the margin.
In puncture cultivations only fine points appear along
the track of the needle, but on the surface a delicate

* Miller, Deutsche med. Woch., 1885, Nr. 49.

376

BACILLI WHICH CAUSE PUTREFACTION.

greyish-white veil-like growth is formed, which is some-
what thicker, and irregular at the
margin. On potatoes the hacillus
forms luxuriant glistening, light-
brown cultivations ; on blood serum,
thick, whitish lines. In all these
nutrient media a foul smell is de-
veloped. — Animals are not affected
by small doses administered subcu-
taneously, but when the quantity is

larger a localised suppuration occurs.

Fig. 100.— Bacillus
Pfpasset) xV90US

Bienstock's

faeces.

Bacillus putrificus coli (Bienstock).

These are thin, actively moving rods, about 3 /*. in
length, though often shorter, and often arranged in the
form Of iong threads. When spore formation takes
place a thickening of the rod occurs at one, or, more
rarely, at both ends, and this thickened part becomes
gradually isolated from the rod, and assumes a spherical
Spore forma- form. This spore remains for some time in connection
germination. with the rod, giving it thus the form of a drum-stick,
and the rod continues to move about with the spore
attached to it, that end of the bacillus being in front.
As the result of the gradual disappearance of the rod
the spherical and very highly refracting spore becomes
free ; if this spore is introduced into suitable nutrient
material it becomes narrower and gradually elongates
to form a rod. From these freshly formed rods
chains of very short rods arise, these shorter bodies
gradually growing to form longer rods and threads. —
The growth of the bacilli on nutrient gelatine has
at first a mother-of-pearl aspect, but as it becomes
older it acquires a yellowish colour, and presents a
homogeneous appearance without any striped arrange-
ment. More accurate statements as to the cha-
racters of growth are as yet wanting. Bienstock was
able to demonstrate by careful analytical fermentative
experiments that the bacilli can split up albumen ener-
getically ; when small quantities of a cultivation of

BACILLUS SAPROGENES. 377

these bacilli are introduced into Cohn's nutrient solu- Chemical
tion containing fibrine in suspension, the following
substances are produced, namely, peptone, ammonia, fermentation,
amine bases, fatty acids, amido fatty acids, tyrosin,
phenol, paraoxyphenyl-
propionic acid, paraoxy-
benzoic acid, indol, scatol ;
further, when the bacilli
act on these individual
products the lower series Fig. 101.— Bacillus putrificus coli
of decomposition products

are produced ; for example, tyrosin gave rise to paraoxy-
benzoic acid, the latter to phenol, &c. Albuminates
of the alkalies are either not at all or only very gradually
broken up. When air is excluded the whole process -Necessity for
runs its course somewhat more slowly, but otherwise
in a similar manner. — The bacillus appears, accord-
ing to Bienstock, to be constantly present in faeces, and
is only absent in that obtained from infants fed exclu-
sively on milk.

Bacillus saprogenes, No. 1 (Rosenbach).

These organisms have been repeatedly obtained by Kosenbach's
Rosenbach from stinking secretions or as an accidental bacilli,
contamination, &c. They are fairly large bacilli, which
produce a large spore at one end. Stroke cultivations
on agar show a greyish-yellow, opaque line, which, how-
ever, is still transparent when viewed by strong trans-
mitted light; it is about 1 mm. in height, and of a
tenacious, soupy consistence ; at a
later period a sort of wavy bloom is
formed, so that the surface presents
a shell-like appearance. The bacilli § *f\*/
also grow on blood serum (nutrient ^/^.^JP' ^
jelly was not tried), and on both of Fig 102.-Bacillu8
these nutrient soils an intense saprogenes, No. 1

. (Eosenbach) X 962.

putrefactive odour is produced.

Egg albumen and meat are rapidly decomposed by the

378 BACILLI WHICH CAUSE PUTREFACTION.

bacilli when air is present, with the production of
foul smell, while in the absence of air only a slight
effect is produced. — Fluids containing these bacilli
when injected into rabbits or dogs, either subcutane-
ously or into the joints, or into the pleura, caused no
bad effects.

Bacillus saprogenes, No. 2 (Eosenbach).

This organism was isolated by Rosenbach from foul

smelling sweaty feet. The organisms are bacilli, thinner

and shorter than those just described. When inoculated

on agar rapid superficial growth occurs ; if a fine stroke

has been made the whole surface appears on the next

day as if sprinkled with minute drops, the growth

gradually spreading over the surface in an equally thick

layer, which at first has a watery appearance, but later is

whitish-grey and of a tough, gelatinous

' I S consistence. The cultivations give off

•Jlft* the foul smell of sweaty feet. Egg

Fig. 103.— Bacillus albumen and meat are rapidly decom-

(EoSTch8)' X°962 POSed in the Presence of air with tlie

formation of stinking gases ; when
oxygen is absent distinct, though delayed, putrefaction
occurs. — When the cultivations were injected into the
knee and pleural cavity of rabbits these animals died
from suppurative inflammations.

Bacillus saprogenes , No. 3 (Rosenbach).

In two cases of suppuration of bone accompanied by
septic symptoms Rosenbach obtained, among other
bacteria, a short, thick bacillus, with
o^ ^ $ rounded ends. When stroked over agar
^ 0 * a layer about 3 mm. in breadth is de-
Fig. 104.— Bacillus veloped in about 8 days at the temper-
m. atureof the room, this layer being of
an ashy grey colour, and almost fluid ;
at the same time the material gives off- a foul putre-
factive odour. Egg albumen is rapidly broken up and

BACILLUS COPROGENES FCETIDUS. 379

undergoes putrefaction after infection with cultivations
of the bacilli in the presence of air ; when air is absent
there is at first violent decomposition, which, however,
soon ceases. — Suppuration occurred in rabbits after
injection of the bacilli into the knee joint.

Bacillus coprogenes foetidus (Schottelius).

In the course of investigations on swine erysipelas Schottelius'
Schottelius found that in all cases some of the puncture bacillus^
cultivations in nutrient jelly, where the infective material
was taken from the organs, more especially from the
mesenteric glands and the spleen, contained, besides the
characteristic colonies of the erysipelas bacilli, also a
few light yellow spherical colonies, composed of larger
bacilli. These rods are about as thick as the hay bacilli Morphological
but shorter ; but the length of the individual bacilli c
differs markedly, according to the nutritive conditions.
They are non-motile. The ends of the rods are
rounded. In cultivations spore formation occurs after
3 or 4 days at the temperature of the room ; the spores
are arranged in rows ; when they germinate the long
axis of the new rod is at right angles to the long axis of
the spore, so that from a row of spores six or eight small
rods may grow out, lying with the long diameter parallel
to each other. The spores are only formed when air is
present, and do not appear in the animal body. In the Cultivations,
deeper parts of the nutrient jelly the
bacilli form pale yellow closed colonies
which do not liquefy the jelly ; on the
surface they produce a fine, transparent,
greyish layer. The cultivations give
off an intense putrefactive odour. On Fig. 105.— Bacillu

,. ,* , , , coprogenesfcotidus

potatoes a light grey dry layer, about (Schottelius) x
•5 mm. in thickness, is formed.— Sub- about 600.
cutaneous injections of small quantities of the cultiva-
tion produced no effect on mice and rabbits ; but very
large quantities produced a toxic effect in rabbits, but
none on swine.

The same organism could be demonstrated by Schot-

380

BACILLI WHICH CAUSE PUTREFACTION.

Penetration
of the bacilli
from the
intestine into
the internal
organs in
swine affected
with
erysipelafe.

telius in the intestinal contents of the swine ; and as in
the cases investigated these bacilli were always most
numerous in the organs lying in the immediate neigh-
bourhood of the intestinal canal, while they became
fewer and fewer in the organs which were more remote
from it, it is probable that they enter the body by the
intestinal ulcerations which usually occur in this disease,
and that they are purely secondary, and on the whole
without any important significance.

Proteus vulgaris (Hauser).

Hauser's Hauser has shown that in putrefying animal sub-

bacilla. stances, in all putrefying meat infusions, in the contents

of putrid ulcers, &c., three species of bacteria almost
always occur which show many characters in common,
Morphological but also some constant differences. — The most common
of these varieties — Proteus vulgaris — forms rods on an
average "6 /x. in thickness, and of very varying length ;
according to the conditions of their life they are some-
times very short, forming almost spherical bodies, some-
times they have the appearance of bacilli 1'25 to 3*75 /*.
in length, sometimes they appear as threads. These
threads are sometimes twisted and convoluted, some-
times they present an appearance like plaited hair.
Hauser designates these formations as spirilla and
spirulina; they, however, give the impression of acci-
dental twistings caused by a variety of external con-
ditions, and not of a characteristic type of growth
recurring in successive generations (see p. 175). — Many
of the rods are in active movement ; in some distinct
long cilia can be seen. Involution forms are frequently
observed, large, for the most part spherical bodies, on an
average 1*6 p. in diameter.

The growth of these rods in 6 per cent, nutrient jelly
is extremely characteristic. At the temperature of the
room round depressions, containing liquefied gelatine and
whitish-grey turbid masses of fungi, appear on gelatine
plates, even after 6 to 8 hours. Under a low power we see
that the gelatine around these depressions is covered by

Involution
forms.

Cultivations.

PROTEUS VULGARIS.

381

a narrow zone of bacteria two or three layers in thickness, Superficial
this zone being at the outer part surrounded by a single cc
layer of bacteria. From the latter tongue-like branches
and projections pass outwards, and these projections,
which consist of groups of rods and threads, constantly
vary their position, become separated, and pass with a
slow gliding movement over the surface of the gelatine,
forming isolated islands and anastomosing threads ; after
some time and at a favourable temperature (20° to 22° C.)

Fig. 106. — Swarming islands of proteus vulgaris (Hauser) X 285.

active changes of situation can be seen to be going on in
all these islands and threads, and circular movements
are more especially evident. Gradually the whole sur-
face of the gelatine becomes covered with wandering
colonies ; from that point rapidly progressing liquefac-
tion occurs, which, after 24 to 48 hours, affects the
whole surface to a depth of about 1 mm. At the same
time there is a foul smell and a marked alkaline reaction.

While these phenomena are observed in the superficial Characters of
colonies, a ray-like arrangement, composed of chains of placed^ y
rods, is formed around the deeper zooglsea masses ; colomes-
these chains as a rule run outwards in a radiating
manner, and show a peculiar movement in that they
often shoot out and then again retract. They gradually
bore more deeply into the gelatine, the ray arrangement
becomes more markedly developed, and the area of the

382 BACILLI WHICH CAUSE PUTREFACTION.

liquefaction of the gelatine extends further ; in the peri-
phery of this area actively moving rods are found, and
also some which show distinct cilia, as well as convoluted
threads which are called spirilla and spirulina. Peculiar
zooglaea formations often extend from the circle of rays
in the form of clubs or screws, or of spirules twisted
like corkscrews. — In 10 per cent, gelatine the migration
of the colonies is no longer observed. In meat infusion
there is active growth and the development of foul smell ;
on the other hand, in Nageli's and Cohn's nutrient solu-
tions there is only slight multiplication of the organisms.
Necessity for If the oxygen is expelled from the vessels employed for
cultivation and replaced by hydrogen, the growth takes
place only very slowly, and the liquefaction of the gelatine
is likewise very gradual, though ultimately complete. —
The temperature optimum is between 20° and 24° C.
Spore formation is never observed ; nevertheless, drying
of the cultivations in a thin layer does not destroy the
Production of organisms. The bacilli set up putrefactive decomposition
putrefaction. jn fregb meat, and also in boiled and sterilised meat;
this, however, does not occur when the fluid added to
the meat has been filtered through plaster cylinders. —
Experiments In animals small doses produce no pathogenic effect,
on animals. S0mewhat larger doses often cause abscesses at the seat
of injection, large doses injected into the veins or sub-
cutaneously produce symptoms of poisoning in rabbits
and guinea-pigs. As the same effect was brought about by
cultivations which had been filtered through plaster of
Paris, it was evident that liquid poisonous materials
were the cause of the pathogenic action.*

Proteus mirabilis (Hauser).

Morphological These are rods *6 /*. in breadth and of very various

characters. length ; they are sometimes almost round, sometimes in

the form of rods 2 to 3'75 /*. in length. This form is

distinguished from the preceding variety more especially

by the much more frequent occurrence of involution

* That this is not the whole truth is evident from Mr. Watson
Cheyne's paper on " Some Conditions of Infection," Brit. Med. Journal,
July, 1886.

PKOTEUS MIRABILIS.

283

forms, large spherical or pear-shaped or spermatozoa- More frequent

like structures 3'75 to 7 /*. in diameter. Further, the foSS***

liquefaction of the gelatine occurs much more slowly

than in Proteus vulgaris. After 12 hours a roundish, Cultivations.

whitish deposit 2 to 3 mm. in diameter has formed on

the jelly plates, and under a low power this presents a

finely granular brownish appearance, diminishing in

thickness towards the periphery in a stair-like manner,

and showing an irregular or wavy outline. As in the

case of Proteus vulgaris, projections pass out from the

Fig. 107A. — Proteus mirabilis (Hauser), swarming
islands, X 285.

border, and these gradually become detached and move
away ; but in this case the movements are on the whole
less active, and the network which is formed at the
surface is characterised by the presence of threads of
enormous length. In the moving islands we find the
most marked involution forms. In the depth of the
gelatine well-developed convoluted zooglaea masses
appear ; the appearances thus produced [recall those
found by Klebs in the organism which he looked on as
the contagium of syphilis, and which he termed heli-

384

BACILLI WHICH CAUSE PUTKEFACTION.

Zoogiaea

comonas. At the outer margin of the puncture a ring-
like zone appears which is filled with a network oi

Fig. 107s. — Involution forms of Proteus mirabilis X 524>

bacilli and] threads, and which shows numerous spirilla
and spirulina forms. After about 48 hours the superficial
colonies become confluent, and form a thick, moist

shining greyish layer,
which presents a
markedly sieve - lik<
appearance. Tota'
liquefaction of the
gelatine does not begir
till after 2 to 3 days.—
The growth in strongei
gelatine, and in th<
other nutrient ma
terials, presents th<
same characters as ir
the case of Proteus
yulgaris ; but in cul
tivations in whicl
oxygen is absent IK
liquefaction of the
gelatine occurs ever
after a long time
Proteus mirabilis is
also similar to th<
foregoing form in Hi

Fig. 103. — Zooglasa forms from a cultiva-
„ tion of Proteus mirabilis X 95.

fermentative action on egg
pathogenic action.

albumen as well as in it*

ANAEROBES WHICH EXCITE PUTREFACTION. 385

Proteus Zenkeri (Hauser).

These are bacilli *4 p. in breadth, and of an average
length of 1'65>. ; sometimes the forms are rounder, at
other times longer. After inoculation on gelatine a'
layer, which towards the periphery becomes thinner like
the steps of stairs, is formed around the point of inocu-
lation, and from the margin of this layer numerous
threads and rods begin to pass out;. after 24 hours we
find large numbers of moving islands, composed of rods
and threads, presenting exactly the same appearance as
in the case of Proteus mirabilis. The deposit becomes
gradually thicker and opaque ; but liquefaction of the
gelatine does not occur (or only quite at the surface).'
The formation of spirilla and spirulina are seldom
observed. — Cultivations in gelatine and blood serum do
not show any marked development of smell ; meat in-
fusion, on the other hand, is decomposed with the pro-
duction of a strong smell. In its other effects Proteus
zenkeri resembles the species previously described.

Anaerobes which excite putrefaction.

In a great variety of putrefying mixtures, as also in
the intestinal contents, in the buccal secretions, &c.,
a peculiar want of correspondence is observed between
the numerous bacteria which are evident under the
microscope, and the species which can be isolated by the
ordinary methods of cultivation. As a rule, by the
latter methods only a few colonies are obtained, or the
nutrient soil remains completely sterile, even after
several days, and in spite of all sorts of variation's in the
composition and temperature. This absence of bacteria Part played by
which can be cultivated appears to be due to a consider- jn

able extent to the fact that many of the species of factive

process.

'bacteria which usually take part in the putrefactive pro-
cess are anaerobes, and hence do not grow under the
ordinal^ conditions of cultivation. The spores of these
bacilli are probably very widely distributed, and almost
always enter putrefying mixtures. As soon as the

25

386 BACILLI WHICH CAUSE PUTREFACTION.

oxygen wliicli is present has been used up by the pre-
liminary development of the aerobes, and as soon as the
nutrient medium has become loaded with the products
of tissue change and of the fermentative action of these
. bacteria, with carbonic acid, hydrogen, and other gases,
the most favourable conditions conceivable for the
growth of the anaerobes are produced, and from this
point they multiply rapidly. If the access of air and
the amount of oxygen in the nutrient substratum is
from the first limited, as is" the case in the interior of
dead animals, and more especially in those which have
died of asphyxia, the anaerobes occupy the foremost
place from the beginning. — Up till recently only the
bacilli of malignant osdema of symptomatic anthrax, of
tetanus, and of the butyric acid fermentation, have been
known as typical anaerobes. Some other anaerobic
bacilli have been isolated in the course of the last few
years in the author's laboratory, and among these are
some which break up egg albumen energetically, and
Methods of which produce intensely foul-smelling gases. These
can be obtained pure by the aid of the ordinary gelatine
or agar plates if kept permanently in an atmosphere
of pure hydrogen. They also develop if a thick layer
of a solid nutrient material is employed, in which case
an upper portion, several centimetres in breadth,
remains completely free from colonies.

The organisms which have been as yet isolated are
for the most part large bacilli which form large, highly
refracting spores in the threads, or after preliminary
development of clostridium forms. At times they pre-
sent the appearance of fine rods with large terminal
spores. The majority do not produce dense and cir-
cumscribed colonies, but branched and knotted' masses ;
gelatine and blood serum are liquefied, and the cultiva-
tions, give off a foul smell varying in degree and
character in different cases. An accurate description of
some of the bacilli which belong to this group will be
shortly published.

BACTERIUM TERMO. 387

The bacterium termo was formerly looked on as the true Bacterium

exciting agent of putrefaction, and it was defined in the *ermo
£ n . • formerly

following manner :— looked on

Cells short, cylindrical, oblong ; 1'5 /*. in length, '5 to 7 /i. the exciting
in breadth; the contents either light or dark, according to the putrefaction
focussing ; the membrane comparatively thick. It occurs in
i -regular dense masses, often arranged in rows, and forming
clumps, or in dense grape-like spherical zooglaea. Flagella
were observed in bacterium termo by Dallinger and Drysdale.
Its mode of movement does not differ in any important par-
ticular from that of any other bacteria; "the cells twist
around their long axis, and ( / o

swim forwards, and then — ' \N*IS'* *<4/|l|*l|'l

again, without turning \f*' f * '* //'/ |||ii//

round, they go backwards, / / j x m/1' //»!'/

or else move in a curved ^ % * \ x / . ' 0\»"VTZ'£/
direction through the ^ / N s ^-rjT^

water, as a rule not very \ — ^ O * J

quickly, with a trembling % „,"•• / ^
or oscillating motion, but cu

sometimes making sudden FiS- 109.— Bacterium termo X 650.
forward movements, ?> isolated bacteria.

. . o. group 01 bacteria,

sometimes rotating

around the transverse axis, and then again remaining quiet
for a long time, and again suddenly moving backwards and
forwards " (Cohn).

J. C. Ewart has made the following statement as to the
mode of. development of .bacterium termo in the moist
chamber. The rods (their size is not stated) grew to form
threads shorter than those of anthrax, and without any ten-
dency to form a network or mycelium ; in the threads small,
refracting, round spores soon appear. Two or three days after
their formation these spores escape from the threads, and lie
either free in the middle of the cultivation, or form zoogltea
masses at its edge. After some time they sprout and form
ymall, narrow rods, which then multiply by transverse
division. The accompanying drawings, however, show that
Ewart was not studying the organism which Cohn had termed
bacterium termo, but some sort of spore-bearing bacillus. —
In order to obtain bacterium termo, we should, according to
Eidam, add a small quantity of an infusion of peas, which has
stood for a long time, to Cohn's nutrient solution, and when
this is done luxuriant development of bacterium termo very
quickly occurs. The bacteria so cultivated, .however, never
caused, in Eidanr s experiments, a putrid smell ; at most a
cheesy odour was produced.

The preceding description is evidently applicable to a large The term an

imperfect one.

388 BACJLLI WHICH CAUSE FEKMENTATJION,

number of bacteria which are now known, and the name at
that time employed cannot be limited to any one of these
species. Hence it is better to give up entirely the
designation "bacterium termo," as it can only be regarded
as a collective name for an inconstant mixture of different
species. According to Eidam's experiments, the bacteria
which were formerly grouped under the term "bacterium
termo " have apparently no relation to the process of putre-
faction ; hence it is probably about time that we should cease
to designate the species which are concerned in putrefaction
as bacterium termo, although this term is still frequently
employed in text-books and scientific papers.

The same statements hold good as regards bacterium lineola,
which was formerly characterised as follows : —

Bacterium lineola. — Cells 3;8 to 5'2 /*. in length, 1*5 /*. ir>

breadth; occurring singly, or in pairs, but never forming

longer threads ; at times arranged in

$ ffl § @ zoogleea form. The contents of the cells

1^.' $ are highly refracting, and contain fatty

/) ^ particles. Their movements resemble

off*^ ™ those of bacterium termo. They occur

Fig. 110.— Bacterium in water from wells, &c., in slimy masses

Hneola (after .Cohn) Qn the gurface of potatoes> &c>

The following are some bacteria which occasion other
fermentative processes, or which dehydrate certain
chemical substances : —

Bacillus Fitzianus.

Fitz's Fitz has been able to set up fermentation in fe'rmen-

aethyl • tescible mixtures consisting chiefly of glycerine, the pro-
bacteria, ducts of the fermentation being in the main aetbylic
alcohol ; the organism present is a bacillus which he
looks on as bacillus subtilis, and which he obtained from
How to obtain the dust of hay. Buchner constantly obtained these
ns^orj am. |)acjjjj when he allowed unboiled hay infusion to stand
in a room for some days, and when he transferred a
small portion of the scum which was then formed to a
sterilised mixture containing 2 per cent, of meat ex-
tract with 5 per cent, of glycerine, and about 10 per
cent, of carbonate of lime. According to the same author
these bacilli have a breadth of 1 p., but their length

BACILLUS ACETICUS.

389

vg-ries considerably from 1*2 /u. upwards ; where the Morphological
rods are longer they are frequently hent at their ends. c
Spore formation takes place in a similar manner to that in
bacillus subtilis.-r-On nutrient jelly they form brownish- Cultivation.
yellow colonies, with sharp outlines and with dark, almost
opaque, centres ; the superficial colonies have the ap-
pearance of brownish-yellow, gelatinous drops lying on
the surface of the gelatine.

Bacillus aceticus.
(Mycoderma 'aceti, Mycoderme du vinaigre, Essigpilz.)

According to Hansen's investigations the bacteria Bacteria of
which have the specific property of transforming the fermentation.
alcohol of fermented liquors into acetic acid can be
obtained with the greatest certainty by placing lager
beer (for example the Copenhagen Carlsberg beer, con-
taining 4 per cent, of alcohol and 5 per cent, of extract)
in open vessels at a temperature between 30° and
34° C., best at 33° C. ; after two or three days a scum
is formed which con- a be

sists almost entirely
of acetic bacteria,
while the fluid has
become muddy and
strongly acid. The
bacilli are short
rods, somewhat con-
stricted in their
middle, the ends of
the rods being cut
off at right angles

to the long axis ; «, two normal chains X 1180.

tli Air OIVA ic o"Krmf b, chain with involution forms X 1180.

r size is about c>> abnormal chain x about 20oo.
the same as that of

the lactic acid bacteria. A characteristic appearance
is their arrangement in long chains, which, often ex-
tend through several fields of the microscope. Some
'of the members of these chains show more or less
distinct variations ; they assume cylindrical, hour-glass,

Fig' ^-

390 BACILLI WHICH CAUSE FERMENTATION.

or spherical shapes, or form long thread-like and irregu-
larly swollen cells. After treatment with iodine solu-
tion, all these forms take on the same yellow colour.
It is not as yet possible to say with certainty whether
some of the cells with thicker walls and of rounder
shapes are to be looked on as arthrospores, and whether
they are, as a matter of fact, much more resistant th.au
the other growing cells, or whether all these variations
from the ordinary form of the chains are in reality in-
volution stages. Nothing trustworthy is as yet known
as regards the mode of growth of this organism on
solid nutrient substrata.

Bacillus, Pasteurianus (Hauser).
(Mycoderma Pasteurianum.)

This organism does not differ morphologically from
the foregoing one ; it forms similar chains and involu-
tion forms, but on treatment with iodine all the cells
take on a blue colour. It was first observed by Han sen
in sweet Copenhagen double beer, and develops best in
beer which contains a large amount of extract, and a
small amount of alcohol, and also in beer wort.

Bacillus urcea (Leube)'.

Bacilli of the These are plump rods with rounded ends, usually
fSmenSti^n 2 /,. in length, and 1 p.. in breadth. On gelatine plates
of nrine. a small, almost transparent, patch appears after 2 days,
and extends in the course of 10 days to about the size
of a farthing ; the colonies have the appearance of a
ground- glass plate which has been breathed upon ; the
'growth extends from the point of inoculation in the
form of circular irregular zones, so that at a later period
a number of concentric rings are seen ; the outermost
zone shows a dentate outline. Growth occurs exclusively
at the surface ; the gelatine is not liquefied. In punc-
ture cultivations the track of the needle appears after
10 days as a very thin grey prolongation, and it is only

BACTERIA IN DENTAL CARIES. 391

rarely that, at its uppermost part, the growth is some-
what broader. Older cultivations have a distinct smell
of herring brine. — It was frequently found by Leube in
old urine. The bacilli are able to convert urea into
carbonate of ammonia, and they do this more energetically
ihan the micrococcus urese.

Leube was able to demonstrate a similar energetic Other bacilli
dehydrating action on urea in the case of two other ^fiar &otior
bacilli, and also of a species of sarcina. The first
bacillus formed thick oval rods, 1*2 to 1*5 /*. in length,
and *7 to *8 p. in thickness ; on gelatine they form
superficial dull grey colonies with sharp margins, which
descend rapidly to the level of the nutrient soil, their
marginal zone being narrow, transparent, and finely
granular. The second bacillus was 1*2 to 1'4 p. in
length, *6 /x. in breadth', had sharply truncated ends,
and formed circular, highly refracting, fairly high
colonies, of a pale greyish-yellow colour, and tough
consistence.

Bacteria in Dental Caries.

The numerous organisms which are constantly present
in the secretions of the mouth and in the deposit on the
tongue and teeth, set up in part very various fermenta-
tive and putrefactive processes, and in part they play a
role in the etiology of dental caries. According to Miller Etiology of
the . first stage of dental caries consists in a decalcifica- dental caries.
tion of the dental tissue by acids, these being chiefly
forme^ in the mouth by a process of fermentation ; and
the second stage must be regarded as a simple destruc- • .
tion of the softened tissue of the tooth by micro-
organisms.

Formerly the most important role in these processes Leptothrix
was ascribed to a particular genus — the leptothrix —
which were defined as long thin threads, *7 to 1 p. in
breadth, apparently without any segmentation and often
united in dense bundles or felt-like masses ; the forms
which occur in the buccal cavity mixed with micrococci and
other fission fungi, were designated leptothrix buccalis.

392

BACILLI WHICH CAUSE FERMENTATION.

Morphological
haracters.

Eeaction \vith
iodine.

Other situa-
tions in which
leptothrix is
found.

Leptothrix
gigantea.

Rasmussen's
species of
leptothrix.

It was regarded as characteristic of the latter form that
the threads were mixed with dense masses of micro-
cocci ; further, according to Leher, the threads of lepto-
thrix huccalis show a special reaction : they assume a
violet colour under the action of iodine and acids ;
iodine alone does not cause this coloration, acids must*
be added at the same time ; but it is not necessary to
employ sulphuric acid (if it were so the reaction would
have a great resemblance to' that of cellulose), very
dilute hydrochloric acid, acetic acid, or lactic acid, act
even better than sulphuric acid. If the. medium is
already acid the addition of iodine alone is sufficient to

produce the colour. It is
not the sheath which
stains ; on the contrary
it remains colourless, and
only the contents become
violet; the septa of the
threads remain unstained,
and hence can be dis-
tinctly seen.

Leptothrix has also been
found in the concretions
in the tear-ducts, as well as in the sputum in cases of
gangrene of the lungs (Traube, -Leyden, and Jaffe) ;
and Leber has recently demonstrated that Leptothrix
buccalis, when inoculated on the cornea, causes severe
suppuration, and that during the course of this process
very fine, long, jointed threads and chains of rods are
developed, which show the characteristic iodine reaction.*
Miller has described a form, under the name of
Leptothrix giyantea, which occurs on the teeth of sheep,
cattle, and other animals, and which forms very long and
thick threads, and may also appear in the form of rods,
cocci, and spirilla.

Rasmussen isolated from the human saliva by the aid
of nutrient jelly and potato cultivations a number of
bacteria, of which he reckons three as species of lepto-
thrix, because they form in nutrient solutions (urine, meat

* Arch. f. dphthalmol, vol. 15.

Fig. 112. — Leptothrix buccalis
X 1000.

BACTERIA IN DENTAL CARIES. 393

infusion) long threads, which break up into short

segments.

It is evident, however, that the designation " lepto- The existence
thrix " cannot be employed as a generic term, for ihe °
most various kinds of bacilli may produce these thread-
like formations, and the threads which occur in the
buccal secretions and in the deposit on the teeth are
probably nothing more than the thread form of various
well known, or still unknown, and widely distributed
bacilli. It is possible, for example, that bacillus
butyricus not uncommonly takes part in the formation
of leptothrix in the mouth ; it is probable, however, that
many other bacilli, more especially anaerobic bacilli, do
the same. Since we have been able to work with better
microscopes and with staining methods it is easy to
convince ourselves, from the marked morphological
differences, that the leptothrix threads of the mouth do
not belong to one individual species ; the threads show
very great variations in thickness, at times they form
spores (or the early stages of sporo formation) arranged
in a characteristic manner ; some threads are stiff an,d
readily broken, others are flexile, &o. . The species of Fruitless
bacteria which have as yet been isolated by cultivation
from the buccal • secretion do not appear to be identical
with those bacilli which form the marked threads which forms,
have led to the designation leptothrix ; as a matter of
fact we only obtain by cultivation a small fraction of the
numerous species which we find by the microscope in
the secretions of the mouth. Miller also states, in his
most recent communication, that the leptothrix 'buccalis
has not as yet been cultivated pure.

As regards the other organisms found in the mouth, Millers
Miller has isolated, during the last few years, 25 different
species, 12 cocci and 13 rod forms. Some of these have teeth
been already mentioned ; we may refer here to the
organism described by Miller under the symbol e.
This forms small curved bacilli, often S-shaped from the
union of two individuals ; it grows on gelatine, and causes
its liquefaction, and is probably identical with the spiril-
lum of Finkler and Prior. The characteristics of the

394 BACILLI WHICH DO NOT CAUSE FEBMENTATION.

other species isolated by Miller have not as yet heen
published in detail.

With regard to the pathogenic bacteria present in the
buccal secretions, see pages 319, 322 and 325 ; as
regards Spirochaete denticola, see below.

Bacilli which are not known to produce Specific
• Fermentations.

Bacillus subtilis.
(Hay bacillus.)

Hay bacillus. These are cylindrical rods, up to 6 /x. in length, and on
an .average about three times as long as they are thick.

Morphological They grow and divide very rapidly; the length of time

characters. between one fission and a second is, at 21° C., about an
hour and a quarter, and at 35° C. about 20 minutes.
Pseudo-threads frequently appear, which can be fre-
quently seen to be made up of rods, by the fact that
they soon become bent in a zig-zag manner; in other
cases, however, they do not present this appearance.
The individual members of a thread are as a rule in
different stages of growth and subdivision, and are
therefore of different lengths. Under various conditions,
which have not as yet heen accurately ascertained, the
rods begin to swarm; the movements are active and
snake-like. At each end of the rod a fairly long and
twisted flagellum can be seen, especially after treatment
with haematoxylin (Koch). — When the substratum
becomes poorer in nutrient material the continued
multiplication of the rods by fission gradually ceases,

Spore forma- and then as a rule spore formation commences. At one
part of the rod which has now ceased to move a dark,
shaded part becomes evident, sometimes more in the
middle, sometimes more towards one end, and ultimately
this portion becomes converted into a highly refracting
spore with dark outlines. The rods swell up at the
same time in some cases in an almost unnoticeable
manner. At the same time that the spores are formed
the contour of the rods becomes dull and indistinct, and

BACILLUS SUBTILIS. 395

they soon disappear entirely, so that the spores become
free, as a rule, during the course of one day. The
spores are 1'2 /*. in length, and "6 /*. in breadth ; when
they are looked at from above they appear round.
Around their dark centre there is a distinct light area,
which is also seen when several spores are lying together.
The sprouting of the spores ofteA does not begin at the Sprouting cf

... the spores.

ordinary temper-
ature of the room
till after 12 hours;
it occurs most
quickly when the
spores are boiled
for five minutes
in the nutrietft
solution, the
material being
then allowed to
cool slowly; under
these circum-
stances sprouting
occurs even after
two to three hours.
When this takes

place the spores

lose their dark Fig. llS.-Bacillus^ubtilis (after Prazmowski)

appearance, the A, colonies of bacillus subtilis.

•i . B spore formation —

clear area disap- a? ^n a pseudo-thread,

pears at the same , *> *? individual rods.

. C, germination ot the spores,

time, and a a — A, successive stages.

lighter zone appears in the middle of the spore. This
zone becomes larger, and then on one side a distinct pro-
jection is formed, at the apex of which the spore membrane
is ultimately ruptured in order to permit the sprouting
portion to pass out. The latter elongates and forms a
rod, but for a time the end still remains sticking in the
opening in the empty spore membrane as if a bladder
were attached to it. The spore membrane can often be
distinctly seen, even after repeated fission of the rods,
and it accompanies the moving bacilli in their wanderings.

396 BACILLI WHICH DO NOT CAUSE FERMENTATION.

The newly formed rod always stands at right angles to
the long axis of the spore; but the long axis of the
newly formed spore is the same as that of the rod in
which it develops; hence, as the result of the spore
formation, there is an alteration in the direction of
growth of the bacilli.*

Bacillus subtilis is Very widely distributed; its spores
are present in the air, in dust, on the surface of all
kinds of articles, and they occur only too often as un-
desired impurities in cultivations of other organisms.
It forms a white efflorescence on the dung of herbi-
vorous animals; on liquid dung it forms, thick wrinkled
skins. This organism grows on a great variety of
nutrient substrata, even when they only contain a little
organic material; it grows in fluids ju§t as well as on
solid but moist substrata; a markedly acid reaction of
the media interferes, however, markedly with its develop-
ment. A cultivation of this bacillus, to some extent
pure, is most easily obtained by infecting the ordinary
nutrient solutions with a little dust from hay, or by
employing an infusion of hay as a nutrient solution; in
the latter case the fluid is boiled for about- a quarter of
an hour; as a result almost all the other fission fungi
are killed, and only the extremely resistant spores of
bacillus subtilis retain their vitality.

According to Buchner, in order to obtain bacillus
subtilis with certainty, it is best to allow hay to stand
at 36° C. for four hours with extremely little water, then
to pass it .through a fine sieve, to dilute the water to a
' specific gravity of 1004, and then to raise about 500 cm.
of this mixture to the boiling point in a vessel closed
with cotton-wool, the heat being continued for one hour,
and only very little steam being developed ; after it has
been boiled the fluid, if kept at 36° C., shows a scum
on the surface after 48 hours, consisting of bacillus
subtilis. It is only when the reaction is very markedly
acid that it is necessary to neutralise the material before
boiling it.
Cultivation011 ^n gelatme plates bacillus subtilis forms small whitish

* After Brefeld, JBotan. Unters., Part 4, and Prazmowski, Lit., p. 47.

BACILLUS SUBTILIS. 897

colonies, which, under a low power, have a yellowish-
brown colour, and an irregular margin, with numerous
hair-like processes projecting from it. At a later period
a narrow clear zone appears around the dark centre,
and beyond this there is a greyish layer consisting of
a circle of rays. At the same time the gelatine is
energetically liquefied. — On agar a thick •wrinkled skin
is formed. On potatoes thick yellowish-white deposits
appear, which, on the second day, have a moist satin-
like appearance, with dry, whitish spots at parts of the
surface, soon extending .over the whole extent of the
layer ; ultimately the cultivation appears as if powdered
with a white granular mass.

These bacilli require plenty of oxygen, and growth, Necessity fo
multiplication, and spore formation only go on in a
normal manner when there is no hindrance to the
access of air ; in vessels devoid of air no development
visible to the naked eye takes place. — Under unfavour-
able conditions of life the bacillus subtilis forms the
most various kinds of involution forms, flasklike
swellings, &c., which, under the microscope, show
a peculiar fatty appearance. According to Buchner Involution
these involution, forms appear especially when the orms'
amount of sugar in the nutrient solutions is markedly
•greater than the amount of nitrogen. The same author
found that even slight variations in the composition of
the nutrient substratum occasion certain alterations in
form, and more especially alterations in thickness of the
bacilli.

Bacillus subtilis does' not appear to exercise any Action on ti
special fermentative action, more especially with reference stratum* 8Ul
to the carbo-hydrates ; the reason why such properties
were formerly ascribed to bacillus subtilis was evidently be-
cause it was confounded with bacillus butyricus and other
bacteria. Vandervelde has recently asserted that bacillus
subtilis can set up fermentation when it is compelled to
exist without oxygen. Vandervelde tried to show this
by careful analysis of the nutrient substratum in which
a pure cultivation of bacillus subtilis had grown for a
considerable time ; he found that glycerine or grape

398 BACILLI WHICH DO NOT CAUSE FERMENTATION.

sugar were used up, and that lactic acid, volatile fatty
No fermenta- acids, carbonic acid, and hydrogen, were produced ; hut
these substances were formed in such small quantities,
and after such a length of time (1 to 2 months) that we
cannot speak of a true fermentation ; on the contrary,
these products only indicate the result of the assimila-
tion and tissue change Of the growing bacilli within
ordinary limits. Further, in Vandervelde's experiments
the absolute quantity of gases produced was not deter-
mined, and there was no certainty as to the -purity
of the cultivation, and for this reason the experiments,
which are nevertheless interesting as regards the
tissue change of bacteria, cannot be regarded as definite
proof of the fermentative activity of bacillus subtilis. —
'eptonising As the only energetic transformation of the substratum
caused by the bacillus we have its peptonising power on
albumen (also on blood serum) and on gelatine, as indi-
cated by the mode of its growth in cultivations. As to
the supposed transformation of hay bacilli into anthrax
bacilli, seepage 241. .

Bacillus aerophilus.

.erobic This organism was found by Liborius in the hygienic

laboratory at Gottingen as an accidental impurity. It .

lorphological presents the appearance of thin rods, |rds of the thickness

haracters. Qf bacinus subtilis ; these vary in length and frequently
hang together, forming straight or zig-zag pseudo-threads.
In the unstained preparations we can at times see a
delicate sheath around the bacillus. They form on agar

ultivations. oval, highly refracting spores. — On gelatine plates fine
punctiform colonies appear after 40 hours, which under
a low power show sharply defined borders, are of an
oval or pear shape, and have a yellowish green colour.
Energetic liquefaction of the gelatine soon commences ;
while the colonies have only slightly increased in size,
and have otherwise remained unaltered, the surface of
the gelatine is liquefied over the whole plate. — In
puncture cultivations a broad sac-like liquefied area is
formed, the upper part of which is greyish -yellow and

BACILLUS MESENTERICUS FUSCUS. 399

opaque, while the lower part is clearer, and is only
rendered somewhat turbid by the presence of a few
flakes. — On potatoes the bacilli form yellowish layers
•with a flat surface and a dull paraffin-like appearance ;
later on the surface at the margin becomes drier, faintly
granular, and assumes a striped appearance as the result
of unevenness of the surface. — The bacillus requires the Necessity cr
presence of oxygen to a greater degree than any of the oxygen-
other organisms as yet examined ; it only grows on the
surface, and ceases to form visible colonies, even when
there is a relatively trivial interference with the supply
of oxygen.

Among the so-called potato bacilli, which readily grow
on the surface of potatoes, and which are often observed
as accidental contaminations, we have — •

Bacillus mesentericus fuscus.*

This organism occurs in the dust of hay, in the air, Brown potato
on the surface of potatoes, &c. ; it is very widely distri- bacillus
buted. The bacilli are small and short, often occurring in
chains of two to four members, and actively mobile ; they
form irregularly arranged, small, refracting spores. — On
gelatine plates roundish, whitish colonies appear with
sharp contour under a low power, and later with delicate
processes of a yellowish brown colour, and finely granular
surface ; liquefaction of the gelatine rapidly occurs. In
puncture cultivations a whitish opacity is formed at first
along the track of the needle, and at the same time
there is a funnel-shaped area of liquefaction at the point
of entrance of the needle, this area extending within 4
to 6 days till it reaches the wall of the glass ; in this
way an upper layer of fluid is formed, in which whitish,
grey flakes are floating. — On potatoes smooth yellowish
deposits appear on the first day, the surface of which,
however, become very quickly wrinkled and brown ; this

* Gottinger hyg. Institut.

400 BACILLI WHICH APPEAE ON POTATOES.

membrane is relatively thin, and does not extend deeply
into the substance of the potato. The growth rapidly
spreads over the whole surface of the potato.

Bacillus mesentericus vulgatus.*

Potato This organism is very widely distributed in nature ;

it is usually, though badly, described under the name
"potato bacillus." The. bacilli are thick and large,
often forming pseudo-threads and spherical spores ; they
have an oscillating movement. On gelatine plates the
colonies present a bluish-white appearance, they are
almost transparent, but later the centre acquires an
opaque white colour ; the superficial colonies can attain
the diameter of almost 1 cm. These colonies sink to
some extent into the liquefied gelatine ; under a low
power they pre'sent the appearance of dark, distinctly
granular discs, with rough borders. The gelatine is
energetically liquefied. In puncture cultivations a
funnel-shaped area of liquefaction is formed at first, but
later the whole of the upper part of the gelatine becomes
. fluid ; in the fluid there are numerous grey flakes, and
on it there is a delicate greyish-white wrinkled skin.
At the bottom of the area of liquefaction a thicker floccu-
lent mass is present; from that point downwards we
still see, for the next few days, the remains of the line
of puncture, clothed with a thick whitish deposit. — On
potatoes a whitish thick growth is formed which is
almost from the first markedly wrinkled, and .which
spreads rapidly over the whole, surface ; if we attempt
to pick up a portion of this skin it is seen that the
colonies have grown deeply into the substance of the
potato ; the raised portions of the skin remain in con-
nection' with the substance of the potato by a tough
mucous mass, so that long threads may be drawn out.
According to Hueppe the bacilli are not able to form any
ropy substances from sugar, but they have an energetic
diastatic action ; they also cause coagulation of casein

* Gottinger hyg. Institut.

BACILLUS MULTIPEDICULUS. 401

in milk in a similar manner to rennet, and cover the
coagula, which are again gradually but almost entirely
dissolved, with a thick tenacious envelope.

Bacillus liodermos.*

These are small, short bacilli, with rounded ends, and Potato
with very active movement. They form on gelatine ^g\ smooth1"
plates colonies with irregular outlines which float on skin-
the surface of the liquefied gelatine in the form of
small white flakes. In puncture cultivations liquefaction
occurs in the whole of the upper zone, and at the bottom
of the fluid greyish-yellow flocks are deposited ; in the
lower part of the track of the needle there is a greyish
growth. — On potatoes a smooth, shining layer is formed,
which spreads rapidly over the whole surface, and gives
to it an appearance as if it had been painted over with
yellowish-white syrup. It is not till after several days
that the smooth surface becomes opaque and slightly
wrinkled, but in any case the wrinkles which are formed
are never so marked as in the foregoing species.

Bacillus multipediculus.-\-

These are long thin non-motile bacilli. The colonies Bacillus with
on gelatine plates present under a low power the appear- inipct-iike
ance of round or oval, sharply outlined, dark discs, from
the periphery of which small, relatively broad processes
shoot out in various places ; these processes are jointed,
consisting of round balls arranged in rows, and gradually
becoming smaller, and they have usually a radiating
direction ; at times, however, they curve, and present a
concentric arrangement. After 2 or 3 days these pro-
cesses are visible to the naked eye in the superficial oval
white colonies ; as these processes only occur here and
there, and are usually only in considerable numbers at
one of the pointed ends, the colony recalls the form of an
insect with numerous feet and antennae. — In puncture

* Gottinger hyg. Institut. f Gottinger hyg. Institut.

26

402 BACILLI OF NO KNOWN PATHOGENIC PROPERTIES.

cultivations the growth is not so characteristic, hut there
also a row of short isolated processes is very gradually
formed, these processes passing out from the whitish
layer which appears along the track of the needle. On
potatoes a dirty yellow layer of moderate extent, and
with a smooth surface, is produced, and the portions of
the potato around the borders of this layer show a dark
colour. — It occurs not uncommonly as an accidental
impurity on potatoes.

Of other bacilli not unfrequently met with in Gottin-
gen the following may be mentioned : —

Bacillus ramosus Uquefaciens.

Branched These are fairly large, slowly moving bacilli with

forming blunt ends. They form on gelatine plates very charac-
baciilus. teristic colonies ; the youngest, when lying deeply in the
material, present under a low power the appearance of
roundish dark discs, the borders of which seem as if
surrounded by hairs ; the same appearance can also be
seen in the superficial colonies, which are for the most
part oval or pear-shaped. With the naked eye we also
observe that a sharply defined funnel-shaped depression
has been formed by a limited liquefaction of the gelatine.
Even after several days this liquefaction has not extended
any further, but the sharply defined, deep circular funnel,
2 to 3 mm. in breadth, is surrounded by several concen-
tric zones of varying breadth and distinguished from
one another to some extent by their colour, these zones
having on the whole a greyish-white ground glass appear-
ance. On a black base these various zones can be par-
ticularly well seen. — In puncture cultivations a slight
funnel-shaped depression, accompanied by liquefaction,
forms at the entrance of the needle ; beneath this funnel
the track of the needle shows a number of branches
which pass off at right angles, the uppermost extending
furthest into the gelatine; as we pass deeper these
branches become shorter. At a later period the lique-

BACILLUS MYCOIDES. 403

faction extends very gradually over the whole surface, and
affects an upper zone of constantly increasing depth. —
This organism was found by Praussnitz as an accidental
contamination ; it is rare.

Bacillus mycoides.
(Earth bacillus.)

These are fairly thick mohile bacilli approaching in Earth bacillus
size the anthrax bacilli, and often forming long pseudo- mc
threads. In the threads oval, highly refracting spores
appear at regular intervals, and this is also the case in
the individual bacilli ; the spore lies about the middle
of the bacillus. — In gelatine plates a whitish turbidity is
formed in which fine whitish threads of irregular inter-
woven and branched appearance are seen. This net-
work of threads attains, even after 12 to 20 hours, an
extent of about 10 mm., and resembles the mycelium of
a fungus so much that one may be in doubt whether it
is that, or whether it is a colony of bacteria. The threads
remain delicate and fine so long as they lie in the depth
of the gelatine, but they increase markedly in breadth and
lose their sharp outlines when they reach the surface.
The individual colonies soon run together as the result of
the growth of this network of threads. Under a low
power the threads are seen to be composed of bundles of
bacilli, which usually lie loosely beside each other, but
are at times densely matted together, and have on the
whole a very curved and convoluted course. When the
threads reach the surface liquefaction of the gelatine
occurs in the uppermost layer, which has already become
diffusely opaque as the result of the growth of the
colonies. — In puncture cultivations minute hairs spread
in the first place from the line of puncture into the
gelatine in dense rows ; later the accompanying lique-
faction obscures the characteristic growth. On potatoes
a whitish tenacious layer is formed which slowly extends
over the surface. — These bacilli are almost always pre-
sent in specimens of earth taken from the surface of

404 BACILLI OF NO KNOWN PATHOGENIC PROPERTIES.

fields or gardens, if these specimens are either directly
dusted over gelatine plates, or if a watery extract of
the earth is made and mixed with, the gelatine.

The following hacilli have also heen more or less
accurately described : —

Bienstock's bacilli from faeces.

Bienstock's These organisms were constantly found in the faeces
faeces bacilli, by Bienstock. They resemble bacillus subtilis in size
and general appearance, but they do not possess spon-
taneous movement; they often form longish threads.
The spores appear in these threads, or even in the
individual rods, usually one in each rod, rarely two, the
spore being generally somewhat nearer one end than the
Morphological other. The size of the spore is about the same as that
characters. Of ^Q spores of subtilis ; the whole substance of the
spore can be stained with warm aniline fuchsine, and is
not decolourised by nitric acid ; with methylene blue
only a faint staining of the periphery takes place. When
the spore sprouts the ellipsoid form becomes gradually
cylindrical, and the substance of the rod which com-
mences to form at each end gradually extends towards
the middle of the spore, and there becomes united
Cultivation, together. — One of this species of bacilli grows out
from the line of puncture in the nutrient gelatine
like a mesentery; main branches of a whitish-yellow
colour run out into the gelatine in all directions,
these branches being united together by smaller anasto-
moses.— The second species grows in the form of white
glistening colonies, at first smooth, but later somewhat
uneven on the surface, the margins of these colonies
showing projections like bunches of grapes; in the
course of 10 or 12 hours it extends over the whole
surface of the nutrient substratum.

BACTERIUM ZOPFII.

405

Bacterium Zopfii.

This organism was isolated by Kurth from the intestine Kurth's bail-
of fowls. It presents the form of bacilli £ to 1 /*. in
breadth, and 2 to 5 /x. in length, usually in active move-
ment. These bacilli form long threads, which, when
growing in gelatine, show numerous bends ; in fact
regular spiral forms may occur, or in some cases felted
structures or circular patches; all sorts of other bendings
and twistings may also be seen. In fluids bacterium

Fig. 114.— Bacterium Zopfii (after Kurth) X 740.
«, threads with commencing formation of balls.

b, breaking up into rods.

c, breaking up into round segments.

e and/, spirilla and spirulina threads.

Zopfii always forms straight threads, and this has led
Kurth to the conclusion that the origin of the bendings
in the gelatine cultivations is a mechanical effect, and
he supposes that, given a certain length of thread,
and a corresponding rapidity of growth, the resistance
which the gelatine offers to the penetration of the thread

is greater than the rigidity of the rod. After some time Ball forma-
tion.

406 BACILLI OF NO KNOWN PATHOGENIC PROPERTIES.

dense balls are formed ; in these balls the threads become
broken up into short or long pieces, varying from 5 to
50 p. in length ; the short portions grow and bend almost
always laterally from the original direction of the thread.
Formation of After some time growth ceases, and the organism be-
bodiesCa comes broken up into spherical individuals, described
by Kurth as cocci. The rows of cocci remain in the
gelatine united in the form of balls ; when sown on new
gelatine, rods and threads are again formed within 16
hours. The round forms appear when the nutrient ma-
terials are becoming exhausted ; they are not able to
multiply by fission, but they can under favourable cir-
cumstances sprout out in the form of short rods.
Biscuit-shaped pairs of cocci also occur, which are,
however, regarded by Kurth only as a more or less
advanced stage of the subdivision of a rod into two
cocci. These biscuit-shaped pairs at times show swarm-
ing movement. The behaviour of the cocci when
dried appears to be especially important ; while the
rods die in the dry state after 52 to 108 hours these
Are these coccus forms live for 17 to 26 days. The cocci also
^1 ores? re^u their vitality for a very long time, for even more
than 82 days, in the exhausted nutrient solution. From
the biological characters mentioned above, and in corre-
spondence with our previous definition of micrococci
and spores respectively, Kurth looks on these spherical
forms as spores. On the other hand, we have the fact
that the round cells of this bacterium are not much more
highly refracting than the bacilli, that they stain intensely
with aniline brown, and that there is no difference between
them and the bacilli in their resisting power to high
temperatures. Nevertheless a higher refracting power,
difficulty in staining, and resistance against heat have
not as yet been looked on as indispensable for the
assumption that any given cell is a spore, and as a
matter of fact such an assumption cannot be made so
long as the general characters have been studied on only
a very small proportion of the existing spores. The only
two important criteria which must be required on the
part of a spore are a certain resistance against external

BACILLUS MEGATERIUM. 407

influences which favours the maintenance of the species,
and more especially a resistance against the effect of
drying ; and secondly, the fact that these cells do not
multiply, but can give rise to an organism resembling
the mother organism. These two requirements are
completely fulfilled in the case of the round cells of
bacterium Zopfii, and hence we have in this case un-
doubtedly a spore formation which only differs from the
other spore forms as yet known in that the resistant
properties depend less on a thickening of the cell con-
tents than, probably, on an alteration of the cell mem-
brane.

These bacilli grow well on nutrient jelly (2 per cent. Cultivations,
meat extract and 2J per cent, gelatine). After 24
hours a thick, whitish-yellow layer is formed along the
line of inoculation, and in the course of the following
24 hours white anastomosing lines develop, and pro-
ject from the original line in radiating directions, so
that the appearance of the colony when looked at super-
ficially is that of the mycelium of a fungus. The
growth, however, only occurs on or under the surface,
and never extends above it; on the other hand
the organism requires a large amount of oxygen, and
does not grow therefore in the deeper layers of the
gelatine. No growth occurs on blood serum ; a diffuse
turbidity occurs at first in a 2 per cent, solution of
meat extract, and later a thick, whitish deposit is
formed at the bottom. The optimum of temperature
seems to be about 20° C. ; the swarming movements
of the rods cease at from 33° to 37° C. ; from
37° to 40° C. involution forms appear, and when this
temperature is continued for some time the bacilli lose
their vitality. — Experiments on animals show that the
bacilli are harmless saprophytes.

Bacillus megaterium (de Bary).

janism was first observed by d

Dage leaves. It presents the fo

2'5 p.. in thickness, and cylindrical inform, with rounded

This organism was first observed by de Bary on Morphological
boiled cabbage leaves. It presents the form of rods c aracters-

408 BACILLI OF NO KNOWN PATHOGENIC PROPERTIES.

Spore forma-
tion.

Germination
of the spores.

Cultivation.

ends ; it elongates till it is four to six times as long
as broad, and then divides transversely into two halves ;
when acted on by alcohol or tincture of iodine the rods
are seen to be composed of short segments. They are
slightly bent; at times they form chains, which, however,
rarely consist of many segments. The rods are in con-
stant, though relatively slow, movement ; flagella have
not been observed. At a later period it can be seen
that each rod is composed of four to six isodiametric
cells, separated from each other by delicate transverse
divisions ; a small, round, highly refracting body soon
appears in the cell, this body increasing in size while
the surrounding protoplasm gradually disappears ;

after a few hours it be-
{ comes converted into a
longish cylindrical spore.
The latter is very highly
refracting, of a bluish ap-
pearance ; the membrane
of the mother cell gradu-
ally disappears ; and the
spore becomes free.
During the process of
formation of the spores
the movement of the

Fig. 115.— Bacillus megaterium. (After rods becomes slower, but

de Bary.) ^QGQ not entirely cease.

I', short r°oa°x mm' When the spore germi-

^, their appearance after the action of nateg its dark outline
iodine solution.

e~f, spore formation. and its highly refracting

character disappear, and

it gradually increases in size till it has attained the normal
breadth of the rod. When this has occurred a delicate
membrane, which is torn transversely or obliquely, is
suddenly separated from the surface, and the rod
passes out of this membrane. — The bacilli grow at
20° C. in solutions of grape sugar and meat extract, or
in meat extract alone with or without gelatine. The
gelatine is liquefied as the result of the growth of the
bacilli.

VARIOUS BACILLI. 409

Bacillus tumescens (Zopf).

This organism was observed by Zopf on boiled carrots kept
fairly moist ; it forms there a tough, wrinkled whitish skin,
which consists of small disc-like gelatinous masses. The skin
contains narrow rods arranged in zooglaea forms, these rods
forming at a later period shorter joints, and in these shorter
joints spores. Its other characters are not as yet known.

Bacillus ulna (Cohn).

This organism was first observed by Cohn, and then by Praz-
mowski, in decoctions of boiled egg albumen, and also under
the shell of an egg. They are rods 1'5 to 2 '2 p. in breadth and
of varying length, attaining at least 3 p.. ; they are mobile. As
regards the formation of threads and spores, they resemble
bacillus subtilis ; the spores are 2'5 to 2'8 /*. in length, and
over 1 p. in breadth. This organism only grows on soil which
is rich in albumen, for example, in decoctions of boiled egg
albumen. These fluids become turbid on the day after inocu-
lation, and cloudy masses are formed, which after some time
collect on the surface of the fluid, and there run together to
form a thick, but dry skin ; the latter consists of very long
matted bundles and balls of pseudo-threads. There is no
formation of any gelatinous material. Fructification occurs
in the skin on the third or fourth day. The pieces of albumen
are not attacked to any marked degree by the growth of the
bacilli ; they retain their consistence and do not give rise to
any putrefactive odour.

Bacillus Hansenii (Rasmussen).

Motile rods 2'8 to 6 p. in length, and '6 to '8 /*. in breadth.
They form spores 17 /*. in length and 1*1 ^ in breadth.
They give rise to a whitish-yellow skin 011 meat infusion,
malt decoction, &c., at a temperature of 31° to 33° C. On
potatoes the growth is of a chrome-yellow colour ; at a later
period it becomes drier and orange-yellow, or yellowish-brown
in colour, and gives off a fruity odour. The pigment is in-
soluble in all the ordinary media (water, alcohol, chloroform,
lyes, acids).

Bacillus tremulus.

Shorter and thinner than bacillus subtilis, with a flagellum
at each end. It has a peculiar tremulous or rotatory movement.
The spore is thicker than the body of the bacillus, and it pro-
jects from the bacillus like a bladder; the completely formed
spore usually appears on one side of the rod. When the growth

410 BACILLI OF NO KNOWN PATHOGENIC PROPERTIES.

is luxuriant, there are usually two or three completely formed
spores and some imperfect ones. — This organism was found
by Koch on putrefying vegetable infusions, on which it forms
a thick gelatinous skin.

Bacterium merismopedio'ides (Zopf).

This organism was found by Zopf in a decoction of stinking
mud from the Panke river. " It forms threads which are
not constant as regards thickness, but vary between 1 and
1'5 fM. They divide in the first instance into long rods, then
into short rods, and finally into cocci. It is clear that as the
threads have varying diameters so the cocci must vary
correspondingly in size. The latter become free, and then
show active movement. When they come to rest they form
on the surface of the water masses or superficial scums, as the
result of continued division in one direction ; and later, as the
result of division in two directions, the very characteristic
' tafel ' colonies are produced, which are morphologically quite
similar to the little tablets of the merismopedic state of the
phycochromaceae. These colonies consist of 64 x 64 cells or
more. Their walls become gelatinous as time goes on. When
the colonies are numerous, and in close contact with each
other, their gelatinous sheaths run together, and thus we
have a continuous zooglaea which always forms a thin scum
on the surface of the water. — The cocci swarm under suitable
nutrient conditions (in fresh mud decoction) out of the tablet
zooglaea, and again develop to rods and threads." The de-
scription given by Zopf, and the fact that the cultivations
were exclusively carried 011 in fluid media, give rise to the
suspicion that the observations depend on the presence of
ji mixture of various kinds of bacteria.

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415

in. SPIRILLA.

SPIRILLUM CHOLERA ASIATICS.

(Kommabacillus, Bacille-virgule cholerigene.)

Numerous investigations formerly made with the view
of finding the causal organism of cholera, which was
long suspected to exist, led to no certain results ; the
discovery of micro-organisms by Pacini in 1854, and by
Klob in 1867, were of no value. It was not till 1884 Koch's dis-
that Koch succeeded in discovering as the causal agent choiera°f
of Asiatic cholera a peculiar species of bacteria which bacilli.
can be constantly demonstrated in the intestinal con-
tents and in the dejecta of those suffering from cholera,
and which is never found in the intestinal contents in
healthy persons, nor in those suffering from other
diseases ; it is exclusively limited to the cholera intes-
tine, and is present there in largest numbers the more
violent the disease. These bacteria are very small,
generally bent like a "comma," but at times forming
long screw-like threads, and they grow in nutrient gela-
tine, on plates and in puncture cultivations, in the
form of characteristic colonies which slowly liquefy the
gelatine.

On examination of numerous cases of cholera, Koch Condition of
was unable to find, in the blood or organs, in
spite of the most careful investigations, any bacteria
which could be suspected as taking part in the infec-
tion ; this result might have been expected, as the
important pathological alterations only occur in the
intestine, and not at all, or only to a subordinate degree,
in the liver, spleen, kidneys, &c. (Virchow*). In the
intestine Koch found various alterations according to

* Verhandl. d. Chol.-Conferenz., 2 Jahr, 1885,

416 SPIRILLUM CHOLERA ASIATICS.

in acute tin- the intensity and duration of the process. In some

complicated

cases of cages running a very acute course there was only slight

cholera. swelling and rosy red coloration of the mucous mem-

brane of the small intestine ; and the contents of the
intestine were colourless like rice-water, or better, like
gruel. In these cases the comma bacilli were usually
present in very large numbers in the intestinal contents,
In more pro- often almost in pure cultivation. If the morbid process
3es' had lasted longer the mucous membrane showed some-
what more marked alterations ; more especially there
was a patchy redness, which was particularly noticeable
at the margins of the follicles and of Peyer's patches.
At the same time it was found that the comma bacilli
had penetrated into the mucous membrane ; in sections
the comma bacilli were found in the tube-like glands,
and had to some extent penetrated between the epi-
thelium and the basal membrane. Nearer the surface
other bacteria were also frequently present, usually
thicker or finer bacilli which had passed more or less
deeply into the mucous membrane; but this had evi-
dently occurred after the entrance of the comma bacilli,
which always lay most deeply, and which had, as it were,
In typhoid prepared the way for the other bacteria. — In a third cate-
gory of the cases all sorts of secondary alterations had
occurred in consequence of the longer duration of the
disease ; the lower portion of the small intestine was of
a dark brownish red colour, the mucous membrane
showed superficial haemorrhages, and at times it had
undergone a superficial necrosis, and was covered with
diphtheritic deposits. In correspondence with this, the
intestinal contents were no longer colourless, but con-
sisted of a bloody stinking fluid, and in it the comma
bacilli were often difficult to recognise on account of
the presence of numerous other kinds of bacteria. —
Methods em- ln ail these cases Koch found that the following was the
demonstration best method for discovering the bacilli. For their
demonstration he employed either fresh dejecta, where
possible those of a soupy character ; or the contents of
the ileum obtained on post-mortem examination ; or
clothes which had been soiled with dejecta. Koch has

SPIRILLUM CHOLERA ASIATICS. 417

observed that the comma bacilli usually multiply rapidly
on moist linen or moist earth, and that it is not till
after 2 or 3 days that other forms of bacteria have
gained the upper hand. Hence shirts and bed-clothes,
even when they have been kept for some time, are as a
rule still suitable for the discovery of the comma bacilli. —
The microscopical investigation was made by spreading Microscopical
out on cover glasses a drop of the dejecta, or, better, one investi&ation-
of the small mucous flakes which are usually present in
large numbers in the turbid fluid, and which contain
the largest numbers of the comma bacilli ; these cover
glasses were then dried, heated, and stained for 1 to 5
minutes with warm methylene blue or fuchsirie solutions.
It is often difficult to recognise the comma bacilli with Modification
certainty among the large number of other bacteria ; S
according to Schottelius it is of advantage in these
cases, after mixing the dejecta with double the quantity
of faintly alkaline meat infusion, to let it stand in an
open vessel for 12 hours in a warm place (30° to 40° C.).
Under these circumstances the comma bacilli multiply
chiefly at the surface of the fluid, and by taking a speci-
men from the surface, preparations are obtained which
contain almost exclusively comma bacilli in such numbers
as are only otherwise found in the typical soupy dejecta. —
It is more difficult to demonstrate the comma bacilli in Demonstra-
sections of the intestinal mucous membrane. In cases tion of comma

bacilli in sec-

which follow a very acute course the bacilli scarcely tions of the
seem to penetrate into the mucous membrane at all ; in mucous*1
old cases the bacilli which have passed into the mem- membrane-
brane have long since died, and only other bacteria
which entered afterwards are found. The comma bacilli
are best demonstrated in sections of intestinal mucous
membrane which is in the state of patchy redness de-
scribed above; under these circumstances they can be
almost always found in sections through the red border
of the follicles. They are best stained with alkaline
methylene blue ; a suitable method of double staining
has not as yet been found, and this is so much the
more to be regretted as it is by no means easy to see
the comma bacilli in the midst of the cells and nuclei

27

418

SPIRILLUM CHOLERA ASIATICS,

Difficulties of
their demon-
stration in
sections.

Demonstra-
tion by
cultivation.

Constant
presence of
comma bacilli
in all cases of
cholera.

which are stained in a similar manner. An additional
difficulty is caused by the fact that the bacilli only
rarely lie in the same plane, and seldom show the
"comma" form distinctly; as a rule the curve is
directed more or less upwards or downwards, or the
comma may stand almost vertical ; in all these cases a
form results which differs markedly from that of the
comma bacilli in cover glass preparations, where they
are as a rule lying horizontally in one plane. Hence
isolated comma bacilli cannot be recognised in the
tissue with certainty; but where small groups are
present there are usually some which show a distinct
comma form, and which thus lead us to a correct con-
clusion as to the other individuals which are less favour-
ably placed. If these difficulties are borne in mind, the
comma bacilli can be demonstrated in the intestinal
mucous membrane with complete certainty.

Much better than the microscopical examination for
the demonstration of the comma bacilli is the method
by cultivation, which, in fact, never fails for the dis-
covery of other bacteria also, such as typhoid bacilli,
even when a large number of microscopical specimens
have failed to show any organisms. The cultivation is
made in the usual manner by introducing a small
mucous flake from the dejecta, or from the soiled linen,
into a vessel containing liquefied gelatine (5 or 10 per
cent.) ; from the original vessel two dilutions are usually
made ; the contents of all the three vessels are then
poured out on glass plates, and after 24, or at most 48
hours, characteristic colonies appear, which are so typical
that the diagnosis of the presence or absence of the
comma bacilli can be made with certainty.

By the aid of these methods it has been demonstrated
that the comma bacilli are constantly present in every
distinct case of Asiatic cholera, and also that they are
only found in this disease, and never under normal con-
ditions nor in the case of any other disease. Koch has
investigated the dejecta or the intestinal contents in
about 100 cases of cholera in Egypt, India, and
Toulon ; Nicati and Rietsch have investigated 31 cases

SPIRILLUM CHOLERA ASIATICS. 419

in Marseilles, Pfeiffer 12 cases in Paris; cholera patients
have also been examined by Babes and Watson Cheyne
in Paris, by van Ermengem in Marseilles, by Armanni
and Fede in Naples, by Schottelius in Turin, by Ceci
in Genoa, and also by Klein, Buchner, &c. In all these
cases comma bacilli have been demonstrated in the
dejecta, or in the intestinal contents. In microscopical Afewnegative
observations the comma bacilli were distinctly recognised mfcroscopicai
in by far the greatest majority of the cases. Some observations,
observers never failed to find them by this method of
investigation ; the majority have, however, here and
there obtained negative results. The number of these
negative results will probably be still further reduced by
the general use of Schottelius' method. — On the other Constant dis-
hand plate cultivations have never failed in the hands of ^J^soT
the observers mentioned above. It is true that the comma cultivation,
bacilli were not found in every specimen of the dejecta,
more especially in old or complicated cases ; but the
examination of several specimens of dejecta during the
course of the disease, or of the intestinal contents after
death, always yielded positive results. It is probable
that greater difficulties will be experienced in demon-
strating the bacilli in very mild cases, such as frequently
appear to occur during cholera epidemics in individuals
but slightly predisposed to the disease. It may be that
in these cases the number of the bacilli is so small, and
their presence in the dejecta so temporary, that a certain
diagnosis will not be always possible. Hence in this
direction the capabilities of the method have as yet to
be determined.

Comma bacilli have only been found in the vomit in Occurrence of
small numbers, on two occasions by Koch, and on three •
occasions by Nicati and Kietsch, but in these cases it is &c
possible that the material vomited was the intestinal
contents which had passed into the stomach. Nicati
and Kietsch also found comma bacilli in a few instances
in the bile duct and in the gall bladder. — The blood and
the other organs, even the mesenteric glands and liver,
were always free from comma bacilli.

420

SPIRILLUM CHOLERA ASIATICS.

Emmerich's It is necessary for the demonstration of the comma bacilli
denial of the ^hat the observer must be thoroughly acquainted with the
sence of methods employed by Koch, and where the first experiments

comma bacilli. of an observer give negative results, they by no means prove
the absence of the comma bacilli. Thus Emmerich in his
investigations failed at first in two cases to find the comma
bacilli, while in eighteen further cases he was able to demon-
strate their presence; as the result of this fact, which evidently
quite harmonises with the above-mentioned positive results,
Emmerich* raises one of his fundamental objections to Koch's
views, by stating that the comma bacilli are not constantly
found in cholera patients. In further confirmation of this
assertion Emmerich brings forward erroneously the evidence
of Schottelius, who, like all other authors, and like Koch him-
self, was not able to demonstrate the comma bacilli in all
cases by microscopical examination, but who distinctly states,
in the very paper cited by Emmerich, " that according to his
experience the plate method always gives a positive result
even in those cases in which, as the result of microscopical
examination of numerous specimens, 110 comma bacilli could
be found with certainty in the dejecta." f

Exclusive ^n or^er *° demonstrate that the comma bacilli were

limitation of exclusively limited to the cholera process, Koch has

the comma n , . . . TT ,

bacilli to the made very numerous control investigations. He has,
however, never been able to find these organisms in
normal intestinal contents, in diarrhceic stools, or in
patients who had recovered from cholera. In like
manner the very numerous investigations made by other
observers in this direction have given without exception
a negative result; nowhere except in the dejecta of
Asiatic cholera, or on objects which had been soiled
with these dejecta (clothes, the water of a tank), have
the characteristic comma bacilli described by Koch been
found.

'similar bacilli. On several occasions similar comma-shaped bacilli
have been seen, and at first these were erroneously iden-
tified with Koch's comma bacilli ; but on more accurate
study, although morphological differenced could not
be made out, biological distinctions were nevertheless
found between these various species and the true cholera
bacilli, these distinctions being sufficient to allow of

* Arch.f. Hygiene, vol. iii., p. 298.
f Deutsche med. Woch., Nr. 14, 1885.

cholera pro-
cess

SPIRILLUM CHOLERA ASIATICS. 421

their differentiation from each other. This was the
case, for example, with the spirilla observed by Finkler
and Prior in dejecta, by Deneke in cheese, and by Lewis
and Miller in the deposit on teeth. (See below.)

Even Koch's opponents have had to admit that their efforts
to find Koch's comma bacilli elsewhere than in the dejecta of
cholera patients have completely failed. Klein was compelled
by Watson Cheyne's objections to make such an admission;
and Buchiier says in his most recent publication, " Koch's
assertion that the vibrio found by him in the cholera process is
exclusively limited to that process has as yet been unshaken." *
In peculiar contrast to this statement of Buchner's is one Admission of
made by his fellow-worker Emmerich in the same number of ** ?vimi^u'ti?3i
the Arcliiv fur Hygiene, p. 358 : " The markedly alkaline exu- to cholera.
dation, rich in oxygen, washes out the intestine and removes
the numerous micro-organisms which live there, while, on the
other hand, it forms an admirable nutrient medium for Koch's
vibrios, which also occur in limited numbers in the normal
intestine, and which multiply enormously in cholera, and in
many cases awake the suspicion that they are causally con-
nected with the alterations." In support of this assertion, Unfounded
which is of such extreme importance with regard to the Emmerich'3''
etiology of cholera, Emmerich has brought forward no proof,
either from those portions of his experiments as yet published,
or from those of any other investigator, and hence the state-
ment is simply incorrect.

Hence we can no longer doubt that Koch's comma Deductions
bacilli occur constantly and exclusively in Asiatic stamj^ofThe
cholera ; further, that they are found in the intestine in occurrence of
numbers which are larger according as the cholera runs
a purer and more typical course, and they are present t
in the intestine in largest numbers at those parts where cholera
the cholera process has set up the most marked altera- pl
tions, namely, in the lower portion of the small intes-
tine. This coincidence cannot be an accidental one ;
on the contrary, the two phenomena, the cholera
process on the one hand, and the appearance of the
comma bacilli on the other, must stand to each other
in the relation of cause and effect. In explana- Necessity for
tion of this constant concurrence we have only two J^^^*1
possibilities. Either the cholera process is the cause connection
of the presence of the large numbers of the comma

Arch.f. Hygiene, vol. iii., 1885, p. 438. and cholera-

422 SPIRILLUM CHOLERA ASIATICS.

bacilli, or the comma bacilli cause the cholera process.
On the first assumption there are again two explana-
tions of the appearance of the comma bacilli : either
these organisms multiply to a great extent as the re-
sult of the cholera process from a few comma bacilli
Cholera can- constantly present in the normal intestine ; against this,
oatuKofthe however, we have the constant negative results of
appearance of numerous investigations of normal intestinal contents,

tne comma m °

bacilli. along with the other necessary assumption that if this

view is correct the comma bacilli must be distributed in
a very remarkable manner, and must be constantly pre-
sent in the normal intestine of Indians and Egyptians,
as well as in that of Europeans ; and further, that as
the result of any disease we have never as yet observed
a similar constant and exclusive development of a de-
finite form of bacteria under the favouring influence
of the disease. It is evidently quite erroneous to bring
forward as an analogous case the constant presence of
oidium lactis in sour milk,* in which from the con-
stancy of its presence (though as a matter of fact it is
not constantly present) one might come to an erroneous
conclusion as to the etiological r6le of the oidium, for in
this example the second condition necessary to prove an
etiological connection between the comma bacilli and
the cholera process is absent, namely, the exclusive
limitation of the occurrence of these organisms to cases
of cholera ; on the contrary, in the case of oidium lactis
we have to do with an organism which is extremely
widely distributed everywhere, and which can be demon-
strated in other places than in sour milk, and without
any production of acid, and hence it is very easy to see
that it does not stand in any etiological relation to the
formation of acid. There is exactly the same objection
to the other organisms, such as the aspergilli, which
have likewise been brought forward by Buchner as
evidence against the etiological significance of the
comma bacilli. On the other hand, we do not know a
single example in the whole range of mycology where the
constant and exclusive occurrence of a definite species

* Buchner, Miinchner arztl. Int. BL, 1885, ISTr. 50.

SPIRILLUM CHOLERA ASIATICS. 423

of bacterium in any process does not at the same time
imply an etiological relation between the two.

The second hypothesis of the occurrence of comma
bacilli in cholera is still more unlikely, namely, that
Koch's comma bacilli have been developed as the result
of the influence of the cholera disease from other species
of vibrio which are normally present in the intestine.
Such a transformation of one species of bacteria into
another which is well characterised, and which has
remained unaltered in its properties for years when
cultivated under a great variety of conditions, has as
yet never been observed, and certainly not in such a
regularly recurring and exclusive manner, under the
influence of a definite morbid process. Such an hypo-
thesis is without any foundation, and directly contradicts
all the facts which have been obtained as the result of
observation and experiment.

Hence in the present state of our knowledge we can AS a conse-
come to no other logical conclusion than that Koch's ^TsUoo^on
comma bacilli are the cause of cholera. With the same the comma
right with which we infer the etiological significance of cause of
the spirilla of relapsing fever, of the leprosy bacilli, of cholera-
typhoid bacilli, &c., from their constant and exclusive
occurrence in these diseases ; with the same right
with which we must look on the syphilis bacilli as the
cause of the disease as soon as their constant and ex-
clusive occurrence in syphilitic new formations has been
certainly proved, we must also recognise that the comma
bacilli, on account of the proof of their constant and
exclusive presence, are the only and sufficient cause of
Asiatic cholera.

The following facts have up to the present time been Morphological
ascertained with regard to the morphological and bio- the comma °f
logical characters of Koch's comma bacilli : — bacilli.

The comma bacilli usually present the appearance of
short curved rods, which, under certain circumstances
remain in connection with each other, and form long

424 SPIRILLUM CHOLERA ASIATICS.

screw-like twisted threads, and therefore in their simplest
form may be looked on as fragments of spirilla. The
average length of the individual curved bacillus is about
1*5 p.., varying between *8 ft. and 2 ^. ; the average
thickness is from ^ to i of the length. The youngest
individuals either show a very slight curve or no curve
at all ; the more fully formed ones generally show in
fresh unstained specimens a distinct curve, sometimes
only a slight bend, sometimes a full half circle ; in the
dried and stained specimens a larger number show a
less curve or are even straight, the difference being due
to the method of preparation. After division the two-
individuals often remain united together, and thus,

Fig. 116. — (After Koch.) Cover glass preparation
from the border of a drop of meat infusion con-
taining a pure cultivation of the comma bacilli.
Long screw-like threads («) X 600.

according to the age and degree of development, they
form short and slight, or longer and more markedly
bent and S-shaped figures ; when examined in drop cul-
tivations it may be seen that the two component parts
of the " S " do not lie in one plane, but represent the
commencement of a screw. As the result of the pre-
paration we not uncommonly find in stained preparations
e- shaped forms ; it is probable that in this case the
rods have become bent and displaced in the middle, so
that the concavities, which were originally opposed to
Spirilla. eacn other, now look in the same direction. — In drop
cultivations there is almost always a formation of long
screw-like threads or true spirilla, which may consist of
10, 20, or 30 narrow turns; this continued adhesion of
the newly developed individuals, to which the spirilla

SPIRILLUM CHOLERA ASIATICS.

425

owe their origin, is only observed in cultivations which
are kept moderately warm. It is only relatively seldom
that these spirilla can be well demonstrated in stained

Vi jT" i I'M »?'*•'/

mm
,lis

Fig. 117.— (After Koch.) Cover glass
preparation.

Cholera dejecta on moist linen (two
days old). Marked multiplication
of the comma bacilli among which are
S-shaped forms (a) X 600.

Fig. 118.— (After Koch. ) Cover glass
preparation from the contents of the
intestine in a case of cholera.

Nuclei of the dead epithelial cells (a).
Semicircular comma bacillus (b).
Very characteristic arrangement of the
comma bacillus (c) X 600.

cover glass preparations ; as a rule the turns appear
more or less opened out, so that we find almost straight
threads ; or the threads become torn, and we only
obtain short fragments. — Hence the morphological
characters of the comma bacilli are best studied in
drop cultivations ; in order to prepare these cultiva-
tions a drop of alkaline meat infusion (for the method,
see the last chapter) is placed on a cover glass infected
with a minute quantity of a cultivation of comma bacilli,
and then so fixed on a hollow slide by the aid of vaseline
that the drop hangs into the depression in the slide.
The preparation is now kept at from 25° to 30° C., and
the further development of the spirilla is watched from
time to time by means of a high power (oil immersion).

426

SPIRILLUM CHOLEIUE ASIATICS.

Movement of
the comma
bacilli.

Involution
forms.

By the employment of this method we also see that
the comma bacilli are motile. The movement is as a
rule very active, either turning round their axis or shoot-
ing forwards; in the case of the longer spirilla it is
slower, and more of an oscillating character. The
movement is, as a rule, most active at the margin of the
drop, in the neighbourhood of the air.

The comma bacilli multiply very rapidly. — When the
maximum of development has occurred in a drop culti-

'G-

Fig. 119. — (After Koch.) Section of the intestinal
mucous membrane from a case of cholera.

A Brunner's gland (a) cut transversely.

In the interior (b) and between the epithelium and the

basal membrane (c) are numerous comma bacilli X

600.

vation involution appearances generally commence, at
first in a few, and later in numerous individuals. The
dying bacilli lose their characteristic form, shrivel up or
swell out, and in such a state take up the colouring
matter only slightly or not at all. In the swollen
plumper rod there is often such a subdivision of that
portion of the plasma which takes on the stain that, on
treatment with aniline colours, an unstained spot remains
in the middle of the rod which recalls the appearance
of the spores of other bacteria, and has in fact been
erroneously looked on as spores. Further, according to

SPIRILLUM CHOLERA ASIATICS. 427

Babes, longer and broader spirilla are formed in nutrient
media containing alcohol, and at the end of these
spirilla large round bladder-like dilatations appear ; the
latter then become detached, and may remain visible
for a considerable time while the thread breaks up.
These spheres, as well as the spindle and flask-shaped
forms which also occur, are in reality sterile involution
structures.

As yet no multiplication of the comma bacilli by
means of undoubted spores has been observed. Against
the probability of spore formation we have the observa-

•» >

Fig. 121.— Besting forms of the cholera

spirilla according to Hueppe.
a, breaking up of a comma bacillus into

two spheres.

b and c, formation of spheres in spirilla.
d and e, groups of spheres.
Fig. 120. — Involution forms f, spirilla with spheres from an old cul-

of the cholera spirilla (after tivation.

Ermengem) X 700. g, germination of the spheres.

tion made by Koch that in dejecta, linen, soil, &c.,
impregnated with cultivations no living comma bacilli
can be demonstrated if the objects have been thoroughly
dried for a short time.

The involution forms just described, and the peculiar Apparent
distribution of the colouring matter as the result of turn.6
degeneration of the rods, have frequently led to the
erroneous assumption that spores were formed. Thus
Carillon* and Ferranf have described the spherical
dilatations, and CeciJ the formation of the unstained
portions as processes of fructification ; Ferran, in fact,

* Semaine medicale, 1884, Nov.

•f* Gazeta medica Catalana, 1885, Jan.

£ Semaine medicale, 1885, March.

428 SPIRILLUM CHOLERA ASIATICS.

thinks that he has proved that the comma hacilli form part
of the cycle of development of a mould fungus (Perono-
spora). — Recently Hueppe* has described a resting form
of the comma hacilli. As the nutrient soil becomes
exhausted long twisted threads are in the first place
formed ; then at one part of such a thread we have the
production of two spheres which are only slightly larger
than the diameter of the thread, and are more highly
refracting. After a little two or four other spheres appear
along the thread, and at times actual zooglsea heaps,
composed of numbers of spheres, are observed. These
spheres, which are immobile, do not multiply by sub-
division, but, according to Hueppe's direct observations,
they gradually lose their refracting power and elongate
to form a short rod, which then after further growth
assumes the comma form, and subdivides when it has
attained the " S " shape.

Even if this observation of the sprouting of these bodies
were correct, — and Hueppe has only succeeded in observing
it three times, and it is not impossible that in these cases
he was deceived on account of the great difficulties of the
investigation, — it would not necessarily follow that we have
here to do with a spore or with a resting form. It is quite
conceivable that in the course of the involution of the
spirilla a portion of the plasma retains its power of develop-
ment, although this portion cannot be looked on as a spore ;
such an idea would only be justified when it was clearly
shown that this body was distinctly more resistant, and
hence of service for the maintenance of the species, and that
it could resist drying and concurrence with saprophytes
Absence of better than the comma bacilli. Such qualities have, however,
any proof of not been demonstrated, either in the case of Hueppe's

greater resist- Spheres Or in the case of the resting forms of the authors
ing power.

previously mentioned. Hueppe, it is true, says shortly

that the spheres observed by him are more resistant against
drying than the bacilli; -but on account of the great importance
of such a fact this assertion ought to have been accompanied
by detailed proof, and this was so much the more required
as Koch and his pupils have made very numerous experiments
by drying a great variety of cholera cultivations, and among
these, doubtless, some which contained Hueppe's spheres,
without having met with any exception to the slight resisting
power of the bacilli.

* Fortschr. der Medicin, 1885, Nr. 19.

SPIRILLUM CHOLERA ASIATICS.

429

The comma bacilli can be readily cultivated in very Behaviour of
various nutrient media. On gelatine plates they form ^iciilH^
after 24 hours at 22° C. very minute white points which cultivations,
under a low power present the appearance of small round
whitish-yellow refracting discs, without any sharp out-
line, and with an ir-
regular and wavy
margin. These discs
become gradually
larger, they retain their
faint yellow colour,
which only becomes a
little darker at the
central part, but with-
out any formation of

Fig. 122. — Colonies of cholera spirilla
X 100.

zones, and the irregu-

a, after 20 hours.
&, » 30 „

c, „ 36 „

d, „ 48 „

At c there is commencing liquefaction
of the gelatine ; at d the colony has
sunk to the bottom of the funnel-
shaped liquefied area.

lar outline becomes

more distinct; the same irregularity and roughness ex-
tends over the whole surface of the spherical colony, and
as a consequence it pre-
sents a distinctly granular
or furrowed appearance.
The highly refracting
character of these colonies
gives them a clear shiny
appearance, and the sur-
face of the plate looks as if
it had been sprinkled over
with small bits of glass.
The gelatine now begins
to undergo gradual lique-
faction ; even with the
naked eye the gelatine on
the plates appears some-
what depress ed at the parts

„.!,,., n ,1 -i • -,. Fig. 123. — Puncture cultivation of

where the colonies lie ; a KocVs comma bacillus,

small, sharply - defined «, two days old.

funnel, containing fluid,

is gradually formed at this place, the colony lying at the
bottom of the funnel. The liquefaction only extends

Microscopical
appearance of
the colonies in
nutrient jelly.

430 SPIRILLUM CHOLEIUE ASIATICS.

slowly. Where there is sufficient space between the
individual colonies the funnels measure at their surface
scarcely 1 mm. in diameter after 48 hours growth at
22° C., and even after 72 hours their extent is not
markedly greater. — Under the microscope the appear-
ance is less characteristic after the commencement of
the liquefaction. The margin of the area of liquefaction
is circular, and has, for the most part, a sharp outline ;
further inwards a grey circular zone is formed which
contains fluid and small fragments of the colony ; in the
centre the latter appears as a yellowish-brown, dull,
irregularly granular disc with indistinct outline.
i -nurture Puncture cultivations in gdalino show, after 24 to 48

hours, a whitish turbidity along the track of the ncnllr,
and around this a slight amount of liquefaction. In
this way a thin tube is formed, which contains at its
peripheral part almost clear fluid, and at its central
part the original whitish thread. Towards the surface
of the gelatine this tube dilates in a funnel shape, the
upper diameter of which has attained tin; cxl,ciit of
about £ cm. after 48 hours. This funnel is also filled
with fluid, the level of which is often markedly lower
than the surface of the gelatine, so that the upper por-
tion of the funnel only contains ;iir ; this gives rise to
the impression, on cursory examination, as if an air
bubble filled the uppermost portion of the funnel. — This
appearance, however, is not observed in every tube;
slight variations from the above description arc found
according to the concentration of the gelatine, the
temperature at which it is kept, the mode in which the
puncture is made, and the amount of material intro-
duced. In like manner the one or the other culture
characteristic is found in other species of bacteria, and it
is only the sum total of the characters mentioned which
enables us to differentiate with certainty the comma
bacilli from other species.

After three or four days the puncture cultivation shows
a moderate extension of the funnel and of the tube, and
thus a slow increase of tin-, liquefaction; it is not till
after 4 to 6 days that the liquefaction has occurred

SPIRILLUM CIIOLEIUK ASIATICS. 431

to such an extent that it has reached, at the surface,
the margin of the glass ; after 8 to 14 days the upper
two-thirds of the gelatine is liquefied throughout its
whole extent.

On nutrient agar the comma hacilli form a superficial Growth on
greyish-yellow, folded gelatinous layer, without any substrata!10
liquefaction of the suhstratum. These agar cultivations
etain their vitality for a considerable length of time. —
On potatoes kept at the ordinary temperature no growth
can be observed, but at from 80° to 85° C. a light
brown, and later a more greyish-brown, mucous layer is
formed.

The comma bacilli grow very luxuriantly in neutralised
meat infusion, in blood serum, and in milk, the latter
medium not undergoing any noticeable alteration. In
none of these cultivations is there any development of
putrefactive gases, nor any disagreeable odour ; there
is at most a peculiar aromatic and sweetish smell.
(Buchner alone has observed a development of foul
smell in his cultivations of comma bacilli in meat
infusion.)

On the whole the comma bacilli are not very fastidious Behaviour in
as regards the composition of the nutrient substrata. tions^ndTn
It is not till the nutrient solutions become very dilute water-
that the growth ceases. As a rule no multiplication of
comma bacilli takes place in infusions of the strength
ordinarily employed for cultivations if diluted with 40
parts of water, while with somewhat greater concentra-
tion active growth occurs; in the former case there is a
gradual diminution in the number of the organisms in-
troduced. In water,* even when it contains a relatively
large amount of organic and inorganic material in solu-
tion, there is never any multiplication of the comma
bacilli. It is only where, at the margin of stag-
nant water, there is a local accumulation of nutrient
materials from the presence of a variety of solid particles
in suspension and of pieces of mud that development
occurs, and this takes place especially on the floating
solid pieces, and thus for example wo have the explana-

* According to experiments by Bolton, Ztitschrf. Jfygitne, vol. iv.

432

SPIRILLUM CHOLERA ASIATICS.

Relation to
oxygen.

tion of the observation made by Koch, which will be
referred to again, as to the multiplication of comma
bacilli in a tank in India. — The comma bacilli are also
sensitive as regards any acid reaction of the nutrient
medium ; the meat infusion, nutrient jelly, &c.,
employed for cultivations must be accurately neutralised,
or, better, slightly alkaline.

The comma bacilli belong to the aerobes in so far as
they only develop with great activity at the surface of
fluid or solid nutrient substrata, where they are in con-
tact with the oxygen of the air ; it also appears as if they
only moved actively in the presence of a certain amount
of oxygen. Nevertheless their necessity for oxygen is
by no means so great that they cease entirely to multiply
where that gas is limited in amount or entirely absent ;
on the contrary, in that case the colonies only grow
somewhat more slowly and to a less extent than those
which have developed in the presence of air. Thus in
gelatine plates which are covered with thin plates of
mica, and in gelatine tubes from which the oxygen has
been expelled by means of hydrogen, a delayed growth
of the comma bacilli occurs, though ultimately one
quite visible to the naked eye;* and it is this slight
sensitiveness with regard to oxygen that enables the
comma bacilli to multiply to a great degree under all
circumstances, and even in the varying and often rela-
tively slight amount of oxygen which they find in the
intestinal canal.

The temperature has an important influence on the
temperature. growt^ Of t^e cultivations. According to Koch's experi-
ments no growth occurs below 16° C.; at 16° or 17° C.
growth is slight, and it does not begin to be active till
about 17° or 18° C.; much better culture results are
obtained, however, with temperatures between 22° and
25° C., and this is the temperature at which the gelatine
cultivations should be kept if possible; the optimum of
temperature is considerably higher, namely, between 30°
and 40° C., a temperature at which the gelatine becomes
completely fluid.

* Liborius, Zeitschr.f. Hygiene, vol. i.

Influence of

SPIRILLUM CHOLERA ASIATICS. 433

Koch has also made numerous observations with Conditions
regard to the action of various inhibiting and destructive
agents on the comma bacilli. As regards those hurtful
factors, which most frequently cause the death of patho-
genic bacteria in nature, namely, drying and overgrowth
by saprophytes, it has already been mentioned, when
discussing the question of spore formation, that the
comma bacilli in all their stages of development die
with extraordinary rapidity when dried. If a culti- Drying
vation is spread out on a cover glass and exposed to the
action of the air at the ordinary temperature the bacilli
are found to be dead after 2 to 3 hours, so that no
development occurs when such a glass is placed in
nutrient jelly. If care is taken to have the culture fluid
in a thicker layer it may be somewhat longer, but never
more than 24 hours before all the comma bacilli are
found to be dead. It follows from the fact of this great
sensitiveness with regard to drying, which is present in
all the stages of development of the comma bacilli, even
in cultures which have been made under the most vary-
ing conditions, that no true resting spores are formed. —
Further, as the result of these experiments, we must
draw the important conclusion that no living comma
bacilli can be contained in any material which is in a
dried or dust-like state ; and as it is only from completely
dry surfaces that particles of dust can be detached and
carried to other localities by currents of air, it follows
that a transport of living comma bacilli by the air, and
the production of infection in this way, is impossible. —
Comma bacilli which are capable of development can Conclusions as
only be transported through the air for short distances by currents of
when infective fluids are agitated and bubbles are air>
detached, as for instance when waves strike against a
quay or on the wheels of a water-mill, or in washing
cholera linen ; in these cases small bubbles of the fluid
containing bacteria may be brought by currents of air
into contact with predisposed individuals.

The comma bacilli are also very easily injured by the Destruction of
second factor, namely, the overgrowth by saprophytes, bacilli
When mixed with other bacteria they can, if they are

28

434 SPIRILLUM CHOLERA ASIATICJE.

present at first in considerable excess, and if the condi-
tions as regards nutrition, temperature, reaction, and
presence of oxygen, are especially favourable, gain tbe
upper hand in the first instance, and thus form those
pure cultivations which have been observed on the
clothes of cholera patients, on moist soil impregnated
with dejecta, and in the culture vessels prepared by
Schottelius' method ; but after two or three days a
complete alteration in the character of the cultivation
occurs in these cases; the comma bacilli die, and other
bacteria gradually occupy the whole of the nutrient
substrata. If the saprophytes are in excess in the first
instance, or if the sum total of the conditions of life are
not very favourable to the comma bacilli, the latter do
not multiply at all, but the saprophytic bacteria lead
rapidly to the death of the comma bacilli present, either
by using up the nutrient material, or by producing
poisonous products. According to Koch's experiments,
comma bacilli when added to sewage could no longer be
demonstrated after 24 hours; in the water in the Berlin
Canal they died at the latest after 6 to 7 days. In
impure water also they do not retain their vitality as a
rule for a longer time, except when they are introduced
in very large quantities.

Length of life If the two hurtful influences above mentioned are
bLmi iT£urae absent the vitality of the comma bacilli may be of
cultivations. iong duration. They can be kept alive for months in
fluid, or, at any rate, moist, pure cultivations ; in gela-
tine cultivations they have been found living after 3 to
5 months, in agar cultivations after about 6 months (in
one case mentioned byHueppe after almost 10 months).
It is evidently not impossible that an equally long pre-
servation of living comma bacilli may at times occur in
linen which is kept moist, on various parts of the soil,
or on some object which is protected from drying and
from the entrance of other bacteria. But under normal
conditions cases of this kind must be of extreme rarity,
for the comma bacilli are almost always destroyed either
by drying or by the presence of such a large quantity of
water that the substratum is overgrown by other bacteria.

SPIRILLUM CHOLEILE ASIATICS. 435

Among other noxious influences the following have Relation to
been investigated hy Koch, and by Nicati and Rietsch.
Low temperatures did not interfere with the vitality of
the comma bacilli, (even — 10° C.,) the cultivation having
been completely frozen. On the other hand, high tem-
peratures were very active ; exposure for half an hour to
a temperature of 60° C. caused death with certainty, as
did also boiling of the fluid for a short time. Their
growth is also hindered when, for example, 10 per
cent, of alcohol is added to the nutrient substratum ;
or 2 per cent, of sulphate of iron ; or J per cent, of
carbolic acid ; or ^V Per cent, of hydrochloric acid ; or
r,Y,- per cent, of quinine ; or ^rjW Per cen^ of bichloride
of mercury ; the presence of 2 per cent, of common salt
does not interfere with development. With the excep-
tion of bichloride of mercury, these organisms are most
certainly killed by carbolic acid, which renders the
comma bacilli incapable of development when employed
in 3 per cent, concentration for a few minutes.

In order to demonstrate with certainty the etiological Experiments
significance of the comma bacilli it was desirable, if 01
possible, to set up the choleraic process in animals by
inoculation of pure cultivations. Nevertheless from the
first there was but little expectation that this mode of
direct experimentation could be employed with success.
For it has been distinctly demonstrated that no animal
of any species is ever naturally attacked with symptoms
similar to those of human cholera, even although they
live in intimate association with mankind and come in
contact with the infective material of cholera in all sorts
of ways and in places where the disease is endemic or
epidemic.

Numerous experiments on animals made formerly
and also in recent times with the dejecta and vomit of
cholera patients, with the intestinal contents of cholera
bodies, &c., led to no noteworthy result. On some

436

SPIRILLUM CHOLERA ASIATIC JE.

Injection of
cultivations
into the
duodenum.

occasions it seemed as if a positive result had been
obtained, but this was due to error in the experiments ;
thus in Thiersch's experiments white mice became ill
after having been fed on filter paper impregnated with
decomposing cholera dejecta, but they also became ill
in the same manner if the cholera dejecta were omitted
from the experiments ; in like manner in the experi-
ments made quite recently by Richards in which swine
were fed with very large quantities of cholera dejecta
and died in from J to 2| hours, we may assume with
certainty, from the suddenness of the action, as well as
from the circumstance that the resulting disease could
not be transmitted in any way to other animals, that in
these experiments he had to do with poisoning from
poisonous products contained in the dejecta, and not
with an infection.

Notwithstanding this slight prospect of success the
experiments on animals have been again taken up by
Nicati and Rietsch, Yan Ermengem, Koch, &c., since
the discovery and cultivation of the comma bacilli ; and,
as a matter of fact, these authors have succeeded in
finding a mode of infection by which a process at any
rate similar to cholera can be set up in animals by
means of pure cultivations of these organisms. Accord-
ing to the facts mentioned above as to the immunity of
these animals to every sort of natural infection, it could
hardly be expected that more than a similarity in the
symptoms would be obtained, and even this result could
only be looked for by the employment of an artificial
mode of infection. In view of these unfavourable pros-
pects of experiments on animals it is more correct to lay
the greatest stress in the proof of the etiological role
of comma bacilli on the demonstration of their constant
and exclusive occurrence in cholera, and not on the
experiments on animals; their constancy has been so
completely shown that as a matter of fact the experi-
ments on animals can be dispensed with.

Starting from the supposition that the seat of the
action of the comma bacilli is the small intestine, but
that infection by the mouth must be a difficult matter,

SPIRILLUM CHOLERA ASIATICS. 437

because the acid in the gastric juice can kill the bacilli
introduced, Nicati and Rietsch tried in the first instance
to inject dejecta of cholera patients and pure cultivations
of comma bacilli directly into the duodenum of guinea-
pigs. In order to exclude the possible influence of the
bile they also tied the bile duct ; it was, however, soon
evident that this was an unnecessary precaution, for the
bile did not in any way interfere with the growth of the
comma bacilli, even when the half of the nutrient
substratum consisted of bile.

On the other hand it has been made out as the result
of Koch's experiments that the result depends very much
on the mode in which the operation is carried out, and
on the greater or less irritation and maltreatment of
the intestine. If the abdominal cavity of guinea-pigs is
only opened to a small extent, and if the injections are
made into the nearest part of the small intestine instead
of into the deeply lying duodenum, so as to avoid dis-
turbance of the intestine, the guinea-pigs die only very
exceptionally (of six animals only one died). If, on the
other hand, the duodenum is drawn forward and fixed
for a considerable time with forceps ; if in short the
intestine is treated in such a manner that hypenemia
and alteration of the peristaltic action results, and if
then | to 1 drop of a pure cultivation of comma bacilli
is injected into the intestinal canal, by far the greater
number of the animals die after from 12 to 48 hours
with symptoms resembling those of cholera. After
death, which occurs with great depression of the body
temperature, hypenemic swelling of the mucous mem-
brane of the intestine is found, and the intestinal
contents are transformed into a very plentiful thin
mucous fluid, which contains enormous numbers of
comma bacilli almost in a pure cultivation. — Other control
kinds of bacteria injected in a similar manner into the experiments,
intestine did not cause death in any case, even though
numerous control experiments were made, with the
exception of the organisms isolated by Finkler and
Prior, which caused three fatal results among ten guinea-
pigs treated in this way. The large number of negative

438

SPIRILLUM CHOLEILE ASIATICS.

Infection of
mouth.

Preparation
of the
animals

Besults.

control experiments shows at once that the operation
per se, when properly carried out, does not place the
animals in any serious danger.

Koch has however attempted to avoid this operation,
which is by no means insignificant, and to obtain infec-
tion of guinea-pigs by the mouth, and he has succeeded
by neutralising the gastric juice in the first instance by
means of soda solution, and subsequently administering
substances which cause slowing of the peristaltic action,
and thus enable the comma bacilli to remain for a longer
time in the small intestine. The following is the mode
in which an experiment of this kind is performed. In
the first place 5 cc. of a 5 per cent, soda solution are
introduced into the stomach of the guinea-pigs by means
of a catheter passed downwards from the mouth (it has
been shown that as a result the intestinal contents have
an alkaline reaction for several hours), and some time
afterwards 10 ccm. of fluid, to which one or several drops
of a pure cultivation of comma bacilli have been added,
are introduced; if only a very little of the cultivation,
one-third of a drop or less, is employed the result is
uncertain. After the injection a dose of opium is ad-
ministered to the animals ; if the opium is introduced into
the stomach of guinea-pigs it scarcely produces any effect,
and hence it is better to inject it directly into the abdo-
minal cavity by means of a syringe, the dose being 1 ccm.
of tincture of opium to every 200 grammes of the body
weight ; the back of the animal is grasped with the left
hand in such a manner that the abdomen is projected
forwards, and then the syringe is rapidly pushed into
the middle of the abdominal wall ; when the operation is
performed in this manner the intestines are pushed to
one side so completely that they have almost never been
injured, nor have any other bad consequences been
observed.

After the administration of the opium narcosis occurs,
lasting from £ to 1 hour, after which the animals seem
quite well. On the evening of the same day, or on the
following day, the animals lose their appetite and seem
ill; a paralytic weakness of the hinder extremities

SPIEILLUM CHOLER.E ASIATICS. 439

gradually develops, the respirations become weak and
slow, and death occurs with symptoms of severe
collapse and with marked coldness, more especially of
the head and extremities. On post-mortem examination
the small intestine is seen to be much reddened, and
filled with a watery colourless fluid containing flakes ;
the stomach and caecum also contain a large quantity
of fluid, and not, as is normally the case, solid masses.
The contents of the small intestine are found in these
cases, both by microscopic examination and by cultiva-
tion, to contain almost a pure cultivation of comma
bacilli. — Infective experiments of this kind were made
by Koch on about 100 guinea-pigs. He also succeeded
in setting up the same fatal disease by employing,
instead of cholera cultivations, the intestinal contents
of an animal which had been infected and bad died.

The force of these experiments is somewhat diminished Control
by the observation made by Koch that some other species expei
of bacteria, as, for example, the vibriones which morpho-
logically resemble the comma bacilli, and were isolated
by Finkler, Deneke, and Miller, when introduced into
the small intestine in the same way at times set up
a fatal disease ; as a matter of fact, however, only 12 out
of 51 animals infected with these bacteria died, while in
the experiments with cholera bacteria the mortality was
almost 90 per cent., and when the dose was larger all
the animals were killed. Employed in the same manner
the anthrax bacilli and the bacteria isolated by Brieger,
as well as a number of other organisms, showed a distinct
pathogenic action, while in the case of a large number of
other species, for example the pyogenic cocci, the bacilli
of rabbit septicaemia and of chicken cholera, &c., no bad
effect resulted. — The opium could be almost completely
replaced by alcohol ; other substances gave less satis-
factory results.

In considering how far the attempts made in these experi- Differences
ments to set up a disease similar to human, cholera have been between he
-successful, it is necessary to bear in mind that in any case in perimentaih
guinea-pigs, which seem to be the most susceptible animals, produced and

vomiting and profuse diarrhoea are very seldom or never "^man

440 SPIRILLUM CHOLERA ASIATICS.

observed, while in these animals after infection with comma
bacilli the enormous distension of the stomach and intestine
with fluid material shows a great transudation into the intes-
tine similar to that which occurs in man, and which leads to
excessive diarrhoea and vomiting. It must further be expressly
pointed out that the pathological anatomical alterations in the
organs, and more especially in the intestines of the animals,
correspond entirely with the appearances found in rapid and
uncomplicated cases of cholera ; extensive alterations, ulcera-
tions, and losses of substance are, according to the best
authors, not characteristic so much for pure acute cholera
cases as for cases in which the course is protracted and com-
plicated.— It is perhaps possible that in the course of further
investigations means will be found to obtain a simpler and
more natural mode of infection in these or in more susceptible
animals. In any case it is right, bearing in mind the above
facts as to the immunity of animals from cholera, not to place
our expectations too high, but rather in the case of cholera
to assign a subordinate importance in the etiological proof to
the experiments on animals.

Toxic effects Where large quantities of cholera cultivations are
cultivations employed toxic effects are produced in the animals. If
m large doses. pure cultivations of the comma bacilli are injected into
the peritoneal cavity of rabbits or into the veins, or in
very large doses into the subcutaneous tissue, paralytic
weakness of the hinder extremities, slowing of the
respiration, and gastro-enteritis set in, and as a rule
death occurs after 1 to 3 hours ; where the material is
applied subcutaneously these results are inconstant ; at
times the animals recover after a few hours and then
remain well ; in the case of starving guinea-pigs a
similar intoxication occurs when the material is intro-
duced into the stomach, and in this case the toxic pro-
ducts seem to be absorbed with especial rapidity. Mice
also die after the injection of large doses into the peri-
toneal cavity. Nicati and Kietsch* were able to demon-
strate that cbolera cultivations when at least 8 days old
caused toxic effects even after nitration through a
Pasteur's filter ; in no case did fresh cultivations pro-
duce any effect. It must also be determined by further
experiments whether, and to what degree, this produc-
tion of poison is influenced by differences in tbe nutrient

* Compt. rend., vol. 99, p. 123.

SPIRILLUM CHOLERvE ASIATICS. 441

substrata, and by the other conditions of life, and also
what is the nature of the toxic substance.

Some experiments have been made on man with Experiments
cholera dejecta or cultivations, partly intentionally and °
partly unintentionally. Thus during the last cholera Experiments
epidemic in Paris Bochefontaine swallowed pills con- tJin^anf01'"
taining cholera dejecta, and Klein in Bombay drank a Klein,
fluid said to contain comma bacilli. In neither case did
illness follow ; but in neither was there any proof that
living comma bacilli were present in the material taken.
And besides, the negative, like the positive, result of
these two experiments was of no value in reference to
the etiology of the disease, as it is well known that by
no means every man who swallows the infective material
suffers from cholera, but only those who are predisposed
to infection ; and, on the other hand, had illness followed
these infective experiments it might quite well have
been objected that it was due to some other cause, for
the experiments were made in a place where cholera was
prevalent.

On the other hand, another experiment unintentionally Infection of
made on man furnishes a further support for the etio- tivations of
logical significance of the comma bacilli. One of those comma bacilli,
who took part in the courses on cholera, which were
held in Berlin in November, 1884, under Koch's direc-
tion, became ill with somewhat severe symptoms of
cholera. At this time there was no case of cholera
either in Berlin or in Germany ; the only possible source
of the infection was the pure cultivations of comma
bacilli with which the physician in question was work-
ing ; and this physician was more predisposed to infec-
tion by these cultivations than any of the other students,
because for some days he had suffered from gastric dis-
turbances and slight diarrhoea. After the appearance of
the symptoms of cholera the watery dejecta of the patient
were examined, and \vere found to contain very large
numbers of comma bacilli which coincided in all respects
with those obtained by Koch from cholera dejecta in
India.

There is, as yet, no definite proof that the virulent

442 SPIRILLUM CHOLERA ASIATICS.

properties of these comma bacilli can be artificially
attenuated, a thing which is by no means improbable,
when we take into consideration the results obtained in
the case of other pathogenic bacteria. According to a
preliminary communication by Nicati and Kietsch, the
virulence of cultivations of comma bacilli is diminished
to a certain extent when the cultivation is carried on for
a long time in meat infusion or nutrient jelly kept at 20°
to 25° C. The protective inoculations which were made
in Spain by Ferran with supposed attenuated cholera
bacilli are so entirely wanting in the necessary experi-
mental and statistical support (as is evident from the
description given by Ferran himself, as well as from the
reports of others,) that they require no serious discus-
sion. As regards the bacilli found by Emmerich in the
bodies of patients who died of cholera, see page 335.

Mode in which In accordance with the facts made out by Koch as to
Infection*51 *ke biological characters of the infective agents of
occurs. cholera, we may suppose that the infection takes place

somewhat in the following manner :—

Distribution The cholera process arises when living bacteria gain
of the cholera admission to the small intestine, remain there for a

bacilli in the . . .

patient. considerable time, and multiply actively. As the result

of their growth toxic materials are formed, which in
the first place cause the death of the epithelium, and
ultimately of the superficial layers of the intestinal
mucous membrane. If they multiply rapidly, and if
large quantities of toxic materials are produced, the
latter are absorbed in large amount and set up general
symptoms, and ultimately paralysis of the organs of
circulation. If in this way death occurs at an early
period there are no deep alterations of the intestinal
mucous membrane, and the appearances on post-mortem
examination correspond to what has been described
above in typical cases, viz., there is a pure cultivation
of comma bacilli in the intestinal contents but no other

SPIRILLUM CHOLERA ASIATICS. 443

noticeable morbid appearances. If, however, the forma-
tion and absorption of the toxic products of the comma
bacilli do not take place so rapidly, and if the patient
survives this stage, the results of the local poisoning, the
necrosis of the mucous membrane, become more marked ;
bleeding occurs, there is enormous multiplication of
putrefactive organisms which grow to the exclusion of
any comma bacilli not yet expelled ; the absorption of
putrefactive poisons sets up typhoid symptoms which
are not a necessary part of the cholera process itself,
and post-mortem examinations made at this stage show
those deep alterations of the mucous membrane which
have been often erroneously looked upon as characteristic
of cholera. — As can be readily demonstrated, the comma
bacilli do not spread into the organs of the body, nor
are they excreted in the secretions at any stage of the
process. Further, direct experiments on animals show
most distinctly that comma bacilli, when they enter the
blood stream, unless when they are in enormous
numbers, and unless toxic materials are injected at the
same time, die very rapidly and do not pass from the
blood in a living state into any organ, or into the
intestinal canal or the urine.*

From these facts, as well as from what has been Sources
previously pointed out as to the vital properties of the iri
comma bacilli, we may draw some important conclusions
as to the mode in which cholera is transmitted. In the
first place the comma bacilli leave the body of the patient
evidently only in the dejecta of the first few days of the
disease (quite exceptionally in the material vomited, see
page 419), and hence it is only these dejecta, and the
objects infected by them, as for example the bed and
body linen, vessels, soil, water-closets, earth on which
these dejecta are deposited, well-water into which the
dejecta may pass, &c., that can serve as sources of
infection. The greater the number of things contami-
nated the more numerous will be the sources of infection,
and the greater the danger of contagion. — These sources

* Wyssokowitsch, Zeitschr.f. Ifyy., vol. i. See chapter on the pro-
duction of disease.

444 SPIRILLUM CHOLERA ASIATICS.

of infection are more especially limited by the fact that
the comma bacilli so readily die, either as the result of
Duration of drying or of overgrowth by saprophytes. As a conse-
quence it is, as a rule, only fresh dejecta, and objects
which have been recently soiled, that are dangerous ; all
materials which are completely dry, such as dry linen,
rags, letters, various kinds of wares, &c., maybe excluded
at once as possible carriers of infection. Where the
materials are moist, and in the case of fluids, the dura-
tion of the vitality of the comma bacilli which have reached
them depends upon their number, upon the number and
kind of saprophytic bacteria present at the same time, and
on various other external conditions ; but in any case it is
only rarely that it lasts for more than a few days. But it
is always possible that some materials, if kept moist and
in which the comma bacilli are preserved in a state of
almost pure cultivation, may act for some weeks as sources
of infection; for example, this is conceivable in the case of
moist cholera linen which is tightly packed, of moist
earth, &c., more especially when the temperature is low.
Points of From the mode of distribution of the comma bacilli in

therbodyint° tlie body, and from the experiments as to their fate
when they are injected into the veins or subcutaneously,
we must draw the inference that natural infection occurs
as a rule only by the mouth.

Modes of IR infection, therefore, we have to deal with two fac-

transport. tors: on the one hand the sources of infection, which,
as we have seen, vary greatly in number and are limited
as regards resisting power; and on the other hand this
one point of entrance. All the conceivable wrays are
evidently, however, not equally suitable for infection ; on
the contrary one or other mode of communication may
be completely excluded, while other modes vary as
regards their power under the influence of external con-
ditions. Currents of air are entirely unsuitable for the
transport of the infective agents, as by them only dry
particles are detached and carried away, while the comma
bacilli do not retain their vitality in the dry condition.
We may ex- The only exceptions in this respect are bubbles of water,
of^iVamd81^8 which may be carried through the air. — Hence a mode

respiration.

SPIRILLUM CHOLERA ASIATICS. 445

of infection which is evidently'of great importance in other
contagious diseases, namely, by the respired air, may be
left out of account in cholera, and in this fact we have
a further reason for limiting the point of entrance to
the commencement of the alimentary canal.

As connecting links between the sources of infection Jnfctb
and the point of entrance we have left therefore : in the contact,
first place, contact between the dejecta or between objects
soiled by dejecta, such as linen, soil, furniture, &c., on
the one hand, and the mouth on the other. This mode
of infection is by no means so uncommon as would at
first sight appear to be the case; where cholera patients
are nursed by attendants who are inexperienced, and who
are not very cleanly in their habits, it must very fre-
quently happen in handling the soiled bed and body-
linen, &c., that infective material adheres to the hands,
under the finger nails, clothing, &c., and that in the
course of the next few hours, before it has become com-
pletely dry, it is brought into contact with the mouth by
unintentional and often unconscious movements.

In the second place, the infective organisms may pass 2. infection of

P Pjt /. . f, , . ,'ii articles of

from some of the sources of infection mentioned to food.

articles of food, and may then reach the point of entrance

along with these. The transmission to articles of food BJ contact.

happens by contact with soiled fingers or with other

objects containing dejecta; further, it will not uncom- By insects.

monly take place by the intervention of insects, more

especially flies. The infective material will frequently

multiply to a great extent on these nutrient substances,

and thus the sources of infection may be increased to

a dangerous extent.

A third mode of infection, which is especially worthy 3. Infection of

,..."-• i ,> -, -i /• -i • i • drinking and

01 notice, is by means ot water employed for drinking other water,
purposes, for the preparation of food, for cleansing plates,
&c. This water may be contaminated by comma bacilli,
either because dejecta are intentionally or unintentionally
poured out in the courts of the house and reach the wells
by gutters, which are not unfrequently present, or by the
water employed for rinsing the cholera linen taking the
same course. In contrast to the other articles of food

446 SPIRILLUM CHOLERA ASIATICS.

we must, however, assume that in the case of the water
ordinarily used for drinking and other purposes multi-
plication of the comma hacilli never occurs, and that there-
fore they can only he present in wells for a relatively
short time. (Compare the investigations by Bolton in
the Zeitschrift fur Hygiene, vol. i.) In the case ol
stagnant water, however, in the bilge water of ships, in
the water in harbours, which is often so extremely dirty,
&c., it is probable that the comma bacilli may retain
their vitality for a much longer time, and in the case of
a tank in India, where the small amount of stagnant
water was not only employed for bathing, drinking, and
cooking, but also for washing the linen and for the
reception of the contents of the water-closets, Koch was
able to demonstrate such a large number of comma
bacilli that it seemed likely that they had multiplied to a
great extent in the tank, and that their presence was in
all probability the source of infection of a number of
cases of cholera which occurred at a later period among
those persons who lived in the neighbourhood.
Influence of But ^e factors which are concerned in infection by

the individual cholera are not exhausted by the varying capabilities of
predisposition. , J J e . ,

the modes of transport. We are also compelled to

assume that cholera does not by any means constantly
occur on every occasion when the comma bacilli have
passed the point of entrance and have reached the com-
mencement of the alimentary canal ; on the contrary, a
further condition comes into play, namely, the so-called
Protective individual predisposition. In a perfectly healthy person
*fc *s ev^en* from what we have learned from experi-
ments as to the destruction of the comma bacilli, and
from experiments on animals, that the comma bacilli
may be destroyed in the stomach, more especially by the
hydrochloric acid present in the gastric juice ; it is also
conceivable that the food may pass too rapidly through
the small intestine, and that also the digestive fluids or
the products of digestion may interfere with the growth
and development of the comma bacilli ; and finally the
energy of the cells and their resisting power towards the
toxic products of the bacilli come into play. According

SPIRILLUM CHOLERA ASIATICS. 447

to the greater or less perfection of the protecting and
regulating arrangements of the body the same infective
material will in one case cause no disturbance, in
another only slight diarrhoea, which leads to rapid
removal of the multiplying bacilli, and the rapid victory
of the body, and in a third to serious illness. — We Acquired
have also the experience that one attack of cholera pro-
duces immunity for a considerable period of time. The
milder or severer course of the disease does not in this
instance appear to make any difference ; the cases also
where the regulating arrangements of the body are in
such good condition that the reaction to the infection is
so slight as scarcely to be designated as disease, ap-
parently acquire this immunity. It has not as yet
been definitely ascertained how long this immunity
lasts ; it is probable that it may last on an average for
3 or 4 years, at any rate it usually lasts for several
months, so that an individual is seldom attacked twice
during the same epidemic.

On the other hand we must assume that the bodv is Predisposing-

factors

more susceptible to infection when dyspeptic conditions
and slight gastric disturbances or overloading of the
stomach are present, also when the digestive process
has arrived at the stage where the acid reaction of the
intestinal contents is slight : and likewise when large
quantities of food can pass into the small intestine after
a relatively short delay in the stomach, and when, on
the other hand, the onward progress of the food in the
small intestine is abnormally slow. The exact value of
these and other assisting factors cannot as yet be
accurately determined, but that as a rule factors of this
kind come into play is clear from the fact that most
cases of cholera occur on Mondays and Tuesdays, after
there have been excesses in eating and drinking on the
Sunday ; and also from the observation made by
Virchow that on post-mortem examination of verv acute
cases of cholera there are always signs that digestion
has been going on actively. — Another predisposing
factor seems to consist in the general weakening of the
body, such as is occasioned by poverty, hunger, and

448

SPIRILLUM CHOLERA ASIATICS.

external
influences.

Results of

practical

experience.

Contagious
cases of
cholera.

disease, whether it be that in this case there is a want
of resistance on the part of the whole body, or some
weakening of the digestive organs.

Hence, on the whole, the occurrence of infection
depends to a great extent on external influences, which
either favour its development or the reverse. The
number of sources of infection is sometimes larger,
sometimes smaller, the modes of transport are some-
times numerous, sometimes few, and may ultimately be
entirely absent ; and it is possible that if the infective
material enters the body it may pass through it without
setting up disease, thanks to the protective arrangements
present.

The question arises whether these views deduced
from the chief facts which have been ascertained as to
the biological characters of the comma bacillus coincide
with the results which have been made out empyrically
as to the mode of spread of cholera. Numerous facts
have rendered it absolutely certain that cholera can be
carried by contagion, the virus being transmitted from
the sick to the healthy. Typical cases of contagion
occur in almost every epidemic ; they are most definite
when the epidemic is only commencing and has not yet
spread widely, while at the height of the epidemic, or in
an endemic area, it is impossible to trace the origin of
the individual cases. — As a classical example of un-
doubted transmission in this way we may mention the
case observed by Virchow in the department of the
Charite Hospital in Berlin, set apart for prisoners, where
three individuals to whom the nursing of a cholera
patient was entrusted became ill of cholera after a few
days, while no case of cholera occurred among any of
the other healthy or sick inhabitants of the hospital.*
Many well-observed epidemics in ships and houses, in
which the reproduction and the transmission of the
disease may be distinctly followed through a number of
patients one after the other, can also only be explained by
contagion. — But for a long time the conclusion drawn

* Weissbach, Virckow's Arch., vol. 55, P. 249.— Virchow in th
Verhandlungen der Chohraconferenz., 1885.

SPIRILLUM CHOLERA ASIATICS. 449

from the facts as to the mode of spread of cholera has Differences h
been that the mode of infection in this disease is ousness oP"
essentially different from, and more dependent on, ex- cholera and
ternal influences than in the case of other infectious
diseases, for example in small-pox. And this experience
is quite intelligible if we bear in mind that in small-pox
there are none of those marked limitations in the
mode of spread of the virus which are seen in cholera.
In the case of small-pox we have a much greater
multiplicity of the sources of infection on account
of the fact that the virus is given off from the whole
skin in the remains of the pustules, and that it is con-
tained in the various secreta ; we have also to do there
with much more resistant infective agents, which evi-
dently withstand drying, and can be carried by currents
of air and dry objects ; hence the facilities for the
penetration of the contagium into the body are very
great ; apparently also the protective arrangements in
the body which render the poison inactive even after
its entrance have much less power. Hence the
spread of small-pox by contagion is so very different
from that of cholera, and the mode of spread of cholera
acquires a special character from the fact that so many
external influences render its diffusion difficult in certain
cases.

In the dependence of cholera infection on external Value of
influences we have the explanation of the fact that in- SScti°
dividuals can be so easily and completely protected against

., . ,. , ., cholera.

against tins disease, much more easily than • against
scarlatina and small-pox. While in the latter cases all
the numerous and permanent sources of infection can
scarcely be attended to, and while the usual mode in
which the virus enters, namely, by the respired air,
cannot be controlled or influenced, it is by no means so
difficult to exclude completely the possibility of the
transmission of cholera. If the dejecta and the objects
soiled by them are cleansed and disinfected all the sources
of infection are got rid of ; if the hands, food, and drinking
water are kept quite clean the most important contami-
nated sources are shut off; if all gastric disturbances are

29

450 SPIKILLUM CHOLEIUE ASIATICS.

avoided the most dangerous cause of predisposition on
the part of the patient is avoided. In correspondence
with these facts we learn from experience that those in-
dividuals who are in a hetter position of life, who are the
most cleanly and moderate in their habits, are attacked
by cholera in much smaller numbers than those who
pay no attention to cleanliness, moderation, or the
digestibility of their nutriment. Hence the English who
are resident in India, and who are able to bestow great
attention on the selection and preparation of their food,
are almost entirely protected against cholera even in the
regions where it is endemic.

The immunity In harmony with this we have also the fact that
nurses. doctors and nurses are very seldom attacked by cholera ;

they are accustomed, by having to deal with other con-
tagious diseases, to habits of precaution and cleanliness
in handling the patients on the one hand, and in their
mode of feeding on the other. Here and there, it is
true, there are incautious or dirty nurses, or the arrange-
ments of the hospital in question are such that the
number of sources of infection is multiplied, and con-
tagion rendered more easy ; and as a result we have in
some epidemics a greater number of cases of the disease
among the attendants. Experience has also shown that
it is on the whole a rare occurrence for other patients
and convalescent persons to be attacked in the same
hospital ; and this is easily intelligible, because these
individuals are usually kept clean, and their food is pre-
pared with a care such as they do not usually employ in
Cholera on their own homes. In like manner in the case of ships,
ships. where as a matter of experience it is relatively seldom

that severe cholera epidemics occur, there is decidedly
less opportunity for the transmission of the contagium
than in private houses ; on board ship the passengers
between decks are compelled to be cleanly, at least to a
certain extent, and as they do not take part in the pre-
paration of the food there is never such a close relation
between the sources of infection, the modes of contagion,
and the predisposed individuals, as is seen in the houses
of the poor. Nevertheless, there are naturally certain

SPIRILLUM CHOLERA ASIATICS. 451

possible modes of transmission in large institutions and
in ships.

Hence it is undoubtedly possible, by rigid and properly
applied cleanliness, to exclude a very important portion
of the modes of transmission of the cholera contagium.
And I may refer to the marked influence — an influence
which will be discussed more in detail afterwards —
which is exercised on the spread of the disease by the
introduction of a good and plentiful supply of water,
and by proper arrangements for the prompt removal of
dejecta.

Having thus arrived at certain definite ideas as to the The epidemic
mode of transmission of cholera to the individual, and cholera. *
as to the factors which come into play, ideas founded
partly on the study of the biological characters of the
comma bacilli and partly on the results of experience
with regard to cholera, we may attempt by the aid of the
same factors to explain also the mode of the peculiar
epidemic distribution of cholera.

Cholera epidemics present a series of very striking Endemic
phenomena, and phenomena very difficult to explain.
We see that cholera is constantly present in an endemic
manner only in Lower Bengal ; in the rest of India,
and more especially in Europe, it occurs only at intervals
in the form of devastating epidemics, and then again
completely disappears from these regions. The starting
point of these epidemics must always be sought in Lower
Bengal ; from thence the disease is evidently carried
into other regions. From what has been said above, Transmission
it is evident that this transmission seldom occurs by any the°sick!a
other materials than the fresh dejecta of the patients,
whether the disease be mild or severe. Hence the
disease can only be carried over long distances when a
patient passes over the whole distance very quickly, and
at the end of his journey still furnishes dejecta con-
taining bacilli, or when a continuous chain is formed,

452 SPIRILLUM CHOLEILE ASIATICS.

of which the individual patients who receive the
infective material from one another, reproduce it, and
pass it on, represent the links. The whole distance
from India to Europe could not in former times be
traversed by one and the same cholera patient ; a chain
of patients was always necessary, this chain stretching
without interruption along the overland route; or the
disease was carried by ships sailing from India to
Europe, the chain being in that case shorter, correspond-
ing to the shorter time required for the journey. These
two chains were evidently not easily established ; even
the shorter one which suffices for the sea journey was
difficult to obtain, because on ships the opportunities for
the propagation of the disease are relatively unfavourable.
It is, moreover, evident that any interruption of the
chain, any failure in the transmission of the contagium
to a new individual, must lead to failure of the spread of
Present mode the disease. At the present time the spread of cholera
cholera. is rendered very much easier, seeing that the network of

railways in Lowrer Bengal communicates with the various
ports of India, so that one and the same patient can be
transported to any of the cities on the coast ; and further,
because a very small number of patients is sufficient to
carry on the disease during the journey from Bombay to
Egypt, and the active contagium may be carried from
Egypt to the nearest European ports by one and the
same patient. — In Europe also cholera can be distributed
by travellers, and we must remember that even a slight
attack of cholera which scarcely causes any noticeable
disturbance of the general health, but in which never-
theless there is multiplication of the comma bacilli and
their deposit in the dejecta, is quite sufficient to transmit
the disease. Striking examples, showing to what
distances the cholera contagium may be carried at the
present time by means of the railway, are furnished by
the case observed by Von Pettenkofer, where a child
suffering from cholera carried the disease direct from
Odessa to Altenburg, and the case published by Biermer,
where the cholera contagium was brought directly from
Rome to Zurich.

SPIRILLUM CHOLERJE ASIATICS. 453

Nevertheless we notice the very striking fact that Irregularity
cholera does not necessarily develop in an epidemic form {Jution of "

in the region to which it gains access ; that all the regions

which lie along the main channels of trade, and to which,

in the case of cholera spreading over Europe, there is no

douht that cholera patients and cholera dejecta frequently

gain access, are not attacked by an epidemic ; hut that,

on the contrary, large tracts of territory and numbers

of towns remain completely free, while neighbouring

provinces and cities are violently attacked. Even within

the same town similar local differences may be found.

There are also a number of places where trade is great, Local pmii*-

which even during the repeated epidemics which have pc

come into Europe have always remained immune, for

example Lyons, Stuttgart, Hanover, &c. These facts

give rise to the impression that in addition to the intro-

duction of the contagium there are some other local

conditions necessary for the epidemic spread of the

disease — in fact a local predisposition.

In like manner there is a peculiar seasonal distribu- Seasonal
tion of the cholera epidemics. As the result of careful Predisi)0sition-
statistical calculations it has been shown that the cholera
epidemics which have attacked the northern part of
Germany always attain their highest point in the latter
part of summer and harvest, while during the spring
months — from February to May — the number of cases
is very few.* In other regions the maxima and minima
as regards season are different: thus in Calcutta the
constant minimum is from June to October, and the
maximum in April ; in Bombay also the cases diminish
in number from June to November, and rise again from
November to June ; in Lahore there is a marked rise
from July to October, which attains its height in August,
and an almost complete absence of cholera during the
rest of the year. These numbers give rise to the im-

* Of the 167,000 fatal cases of cholera which occurred in Prussia
between 1848 and 1859, the following was the relation to the various
months :— January, 1'4 per cent. ; February, March, April, and May
together 1 per cent. ; June, 2'6 per cent. ; July, 5 per cent. ; August,
20 per cent. ; September, 34 per cent. ; October, 21 per cent. ; Novem-
ber, 10 per cent. ; December, 5 per cent.

454 SPIRILLUM CHOLERA ASIATICS.

pression that the epidemics are dependent on some
factors which vary according to the season — on a seasonal
predisposition.
Extinction of A third striking fact with regard to the mode of spread

the epidemics. /.-IT , -, , • -, , , • -i • • ^

of cholera is that in one place the epidemic is often
extinguished, while in other and neighbouring situations
it continues, and that this extinction is observed both
after a short and moderate amount of disease, and after
a long continued and violent outbreak of the plague.

The question arises whether these puzzling facts as
regards the epidemic spread of the disease, which have
excited the greatest interest during the last few years,
may not possibly be solved by a more accurate analysis
of the mode of infection on the same lines as that above
given in explanation of the transmission of cholera from
individual to individual.

What are the It is a priori probable that the peculiar local and
factor? which seasonal distribution of cholera epidemics is brought

y the action of several factors varying according
of cholera to local and seasonal conditions, and depending partly
on the sources of infection available for the spread of
the epidemic, partly on the paths of transport from these
sources to the exposed individual, and partly on the
susceptibility of the latter. In studying the infection of
an individual we become acquainted with a number of
influences by which the sources of infection could be
multiplied or reduced in number, the paths of distribu-
tion enlarged or narrowed, and the individual suscep-
tibility increased or diminished. These factors are also
undoubtedly of equal importance in the epidemic dis-
tribution of the disease ; for we must remember that
an epidemic only originates and spreads when a chain
of new cases follows the first in a continuous series,
and that it disappears when this chain is broken.
Just as the inoculation of the individual requires
certain favourable chances, just as all those infections
which serve for the continuance of the chains are
influenced by chances of all kinds, so the epidemic
will come to an end, chiefly because, owing to external
circumstances, the sources of infection become less

SPIRILLUM CHOLERA ASIATICS. 455

numerous or are entirely removed, or because the usual
paths of transport have become too few, or because the
exposed individuals are immune against the infection.

Accordingly those external factors which can act to a
great extent on the sources of infection, on the paths of
distribution, or on the exposed individuals, will probably
furnish an explanation of the local and seasonal dif-
ferences in the spread of cholera ; and hence we must
study more closely these external factors. We find these
factors partly in meteorological conditions, partly in the
soil, and partly in the habits and customs of different
races. The most important are the following : —

1. Meteorological influences. High temperatures 1. Meteoro-
approaching the optimum of the temperature of the infliaences.
comma bacilli might favour the spread of the disease by
enabling the comma bacilli to multiply as saprophytes,
and by thus multiplying the sources of infection. And Temperature,
the less energy of tissue change, and the less resisting
power of the body by which excessively high temperatures
are apt to be accompanied, appear to increase the indi-
vidual predisposition to a certain degree. — On the other
hand, epidemics are by no means absent in winter, be-
cause these favouring influences of temperature are not
so important that they cannot be completely replaced by
other predisposing factors. It must also be remembered
that in winter we usually employ in our immediate sur-
roundings artificial heating, and thus produce tempera-
tures which are quite sufficient to enable the comma bacilli
to multiply ; and that on the other hand, in summer and
in warm climates sources of infection which may be pre-
served for a long time at a low temperature are more
readily rendered inert by drying, or by the quicker
growth of saprophytic bacteria. On the whole, therefore,
it is only rarely that temperature has a decisive influence
on the spread of cholera.

Very great dryness of the air must render the trans- Moisture of
mission of the disease more difficult, in that it occasions
rapid death of the comma bacilli in the sources of infec-
tion. Cholera linen, soil contaminated with dejecta, &c.,
are under these circumstances only infective for a very

456 SPIRILLUM CHOLERA ASIATICS.

short time, and the chances of spread of the disease are
correspondingly smaller. Further, the nutrient media
are rendered unsuitable for the multiplication of the
comma bacilli by drying of the surface, as well as for the
development of other bacteria which might possibly in-
fluence the individual predisposition. Finally, insects,
which are of such assistance in transporting the infection,
are absent. This result however will only occur where
there is a very great deficiency in the saturation of the
air with moisture, for example in a desert ; moderate
differences in the degree of moisture of the air can only
with difficulty exert a noticeable action. Diminution of
the moisture of the air, such as occurs, for example, in
Calcutta during the so-called "dry season " of the year
(November to April), can coincide very well even with
an increase of cholera if the paths of transport and the
individual predisposition are at the same time favourably
influenced by other factors. On the other hand, it is
conceivable that in a desert climate, such as is present
in Multan and Lahore during the greater part of the
year, and where everything dries up, as it were, under
one's eyes, the conditions favourable for the spread of
the cholera may only be present at most during the
somewhat moister or so-called "rainy" season (July to
October) .

Rain. Very excessive and constant rains will, as a whole,

cause a diminution in the number of the sources of in-
fection and of the paths of distribution. Where, as in
certain parts of India, and also in many villages and
habitations of the poor in European cities, all sorts of
filth and all infective dejecta are collected in the courts
and in the immediate neighbourhood of the houses, and
where attempts are never made to cleanse these surround-
ings, heavy rainfalls, which are powerful cleansers of the
surface of the earth, must lead to diminution and re-
moval of the sources of infection. Where, on the other
hand, the rainfall is slight and of short duration it can
hardly exert any direct action, and will at all events
occupy a secondary position as compared with other
important factors.

SPIRILLUM CHOLERA ASIATICS. 457

2. The nature of the soil is in the first place of im- 2. Influence

,. ., , ,. ., , of the nature

portance in so iar as, according to the declivity and Of the soil,
porosity of the soil, the rain, the house, and the washing-
water, the outflow from water-closets, &c., can be readily
carried off, or is retained in stagnant superficial collec-
tions, or in the uppermost layers of the soil. Where,
as in the suburbs of Calcutta, we have the presence of
tanks, and the artificial elevation of the foundations of
the houses, the conditions are very favourable for the
collection and preservation of infective material during
the dry season of the year. A similar accumulation of
filth and of sources of infection also occurs not uncom-
monly with us in narrow streets and courts. — The influ-
ence of the soil may also vary according to the season.
The chances are evidently favourable for the spread of Dryness of
cholera when a so-called ''drying zone" exists in the
uppermost parts of the soil, so that all fluids and rain S0ll>
which reach the soil remain in the uppermost dry layer
(see Part VI.) ; where there is no drying zone the impuri-
ties and any infective agents present are as a rule carried
to such a depth that they are no longer present at the
surface, and thus many chances of transport to man and
dwellings are removed ; when however a drying zone is
present all infective organisms, which usually reach the
soil in considerable numbers with the dejecta, with the
contents of the night- stools, with the water from washing
clothes, &c., remain for a considerable time in this
upper layer. There the conditions arc favourable for
the preservation of the comma bacilli as wrell as other
bacteria ; and hence a source of infection is furnished
from which the infective material may be carried either
directly to man or to articles of food and other things in
a great variety of ways, e.g. by man, animals and objects,
and also by insects ; and this source of infection is so
much the more dangerous the longer it continues to
exist. — The presence of a drying zone, which is best indi-
cated in our neighbourhood by lowering of the level of
the ground-water, is therefore under certain conditions
an important seasonal predisposing factor for the spread
of cholera, while under other circumstances, such as an

458

SPIRILLUM CHOLERJE ASIATICS.

3. Influence of

drinking

water.

Insects.

5. Habits of
life.

Cleanliness.

unsuitable character of the soil, cleansing of the surface
of the soil, &c., it is much less important than many other
factors.

3. The mode in which the population obtain their
drinking and household water is at times of great impor-
tance. If the water has in the first instance become
contaminated with comma bacilli it forms for a short
time a dangerous source of infection, which leads in the
simplest and most direct manner to the exposed indivi-
duals.— The establishment of this source of infection
may be greatly favoured by the situation of the well, and
its mode of formation ; especially where water is carried
to it from the surface of the soil, or where canals or
gutters from cesspools, &c., lead to the well. The more
of these badly constructed wells there are in a town the
more readily will cholera be spread by the water. Open
and stagnant collections of water are naturally the most
dangerous ; in Lower Bengal such collections form the
source of the water supply, and appear, as a matter of
fact, to be one of the most frequent and dangerous
sources of infection. Where the wells are deep and
well constructed, so that they cannot be contaminated
from the surface of the soil ; or where the water is carried
by well-constructed pipes, this mode of spread of the
infective material is practically absent.

4. Insects deserve especial mention, as they vary
extremely in numbers according to place and season,
and form in all probability a by no means unimportant
mode of conveyance of the poison, a mode which increases
or diminishes according to the number and varieties
of the insects. No quantitative estimate can be formed
with regard to this factor.

5. Certain habits of life can in the case of one nation
furnish greater opportunities for the spread of cholera
than in that of another. The average cleanliness of
the population has the greatest influence in this respect.
The more cleanly the method of handling the sick and
the infected clothes, the more- carefully contamination
of the soil, of the water, and of various other objects with
the dejecta is avoided, the fewer will be the sources of

SPIRILLUM CHOLEIUE ASIATICS. 459

infection. The more carefully the hands are cleansed
and the articles of food prepared, the more will the paths
of spread from existing sources of infection be diminished.
It is evident that in this respect marked differences must
exist between more or less civilised countries ; between
new and well-built, and old and narrow cities ; between
poor and wealthy neighbourhoods ; between the portion
of a city inhabited by the poor and that in which the
better class dwell.

As a special example of the action of general clean- Arrangements
liness we have the effect, often confirmed, of a good of water and'

supply of water and drainage. Formerly these arrange-
ments were supposed to produce their good hygienic
results chiefly by keeping the soil and ground water free
from all putrescible materials, and thus withdrawing the
necessary nutrient substrata from any infective germs
which may have reached them. This interpretation is
no longer sufficient in accordance with our present know-
ledge as to the conditions of life of the pathogenic fungi,
but the good effects of these arrangements for cleanli-
ness still exist as they did formerly, for they lead to
marked diminution of the sources of infection and to a
limitation of the paths of spread. They act by remov-
ing as quickly and completely as possible all the dejecta
and the water employed for cleansing linen, utensils,
&c., without allowing them to come in contact with the
surface of the soil, with wells, &c. ; and further, by pro-
viding an ample and convenient supply of water, so that
cleanliness in every form is favoured, and thus infection
is limited to contact, nutrient materials, and so on.
But even with these arrangements we must not under
all circumstances expect a complete protection against
the spread of cholera, for at certain places and at given
times it is evident that other sources and paths of
infection may develop, and thus the disease may spread
quickly and over a wide area in spite of these sanitary
arrangements.

The mode in which linen is cleansed may be especially cleansing- of
referred to as another of the habits of life which has an f °thes' linen'
important influence on the spread of this disease. Koch

460 SPIRILLUM CHOLEBJE ASIATICS.

lias pointed out that in Lyons, for example, the custom
is not to wash the linen in the house, but on boats in
the quickly-flowing water of the Rhone, or further clown
the stream, for example, in the village of Craponne.
Clothes are soiled with dejecta in almost every case of
cholera ; the infective material retains its vitality under
these circumstances for a relatively long period ; the
linen is a valuable material, which is treated with care
and subjected to many manipulations ; it is handled the
more incautiously in that the cholera dejecta do not
betray their presence by stink, or by any other disagree-
able character. Hence linen is evidently one of the
most dangerous sources of infection, and thus a very
great part of the chances in favour of the distribution of
cholera is removed when, as in Lyons, the linen is with-
out exception cleansed outside the house ; while on the
other hand the greatest chance of infection is furnished
when the linen is kept in the house, washed in leaky
wells, or, as in India, in stagnant tanks.

<j. influence of 6. An important factor which hinders or favours the
pmiispofci- local and seasonal spread of cholera is, finally, the indivi-
tion- dual predisposition of the population. Such a predispo-

sition can in the first place be based on the habits of the
population with regard to food, habits which show marked
differences in different places and at different seasons.
Mode of In one country the people live relatively sparingl}7, in
other countries or towns, or in certain classes of the popu-
lation, a very large amount of food, and more especially
of fluid food, is swallowed. It is further worthy of
notice that in our countries the food is almost always
cooked during winter and spring, while in summer and
harvest raw fruits and vegetables often form a consider-
able portion of the daily nourishment ; these raw materials
often set up mild gastric disturbances, and are also very
suitable for the transport of bacteria. In other countries
a much larger proportion of the food is constantly used
without any preparation. It can easily be understood
that by employing raw food the paths of infection are in
the first place increased in number ; that also as the
result of the gastric disturbances, as well as of the

SPIRILLUM CHOLERA ASIATICS. 461

habit of overloading the stomach, any comma bacilli
which may have entered can the more readily obtain a
footing and multiply in the alimentary canal.

The general nutritive condition, and the energy and
resisting power of a whole population may also show
marked differences, and may under certain circumstances
influence the seasonal or local spread of cholera. Starva-
tion as well as great assemblages of human beings, feasts,
pilgrim festivals, &c., favour an epidemic outbreak,
partly on account of the slight amount of care employed
in the selection and preparation of the food, partly by
the frequent excesses, and partly by the weakening of
the whole body.

A population is apparently in especial danger in Predisposing
which at the time of the first cholera cases gastric dis- |fg*^ances,
turbances are prevalent. Such seasonal prevalence of
mild or severe gastric disturbances, as shown by
diarrhoeas, dysenteric or even choleraic attacks, &c.,
are observed in Germany almost exclusively during late
summer and harvest. It is unfortunately as yet not
possible to understand thoroughly the etiology of this
great increase of gastric disturbances at particular
seasons ; it is conceivable, for example, that the use of
raw fruits or the low temperature so frequent during the
night at this period of the year, and the consequent
liability to cold, are of causal importance : or it may be
due to some forms of micro-organisms for the preserva-
tion, distribution, and reception of which the circum-
stances during these months are particularly favourable ;
for example, these are the months during which in our
country a dry zone is present in the upper layers of the
soil, in which numerous bacteria may remain, and may
be carried as dust by the winds, and further during
these months bacteria are most frequently taken in by
articles of food. Whatever may be the ultimate ex-
planation, we may assume as certain that these autumnal
gastric disturbances, in whatever way they have arisen,
have a special favouring influence OD the epidemic
spread of cholera.

Lastly, the individual predisposition of a population influence *f

epidemics.

462

SPIRILLUM CHOLERA ASIATICS.

may be influenced by the fact that a larger or smaller
proportion of the individuals have been rendered
immune for a time by a previous attack of cholera. As
has been previously stated, we must assume that even
the mildest attack can produce this immunity, so
that after a considerable epidemic a relatively high per-
centage of the population has been attacked. This
circumstance must diminish to a great degree the
chances in favour of the spread of a second epidemic ;
and in India, where there are almost always insuscep-
tible districts which have been recently attacked along-
side of the susceptible ones, the mode of spread of the
epidemics must consequently show peculiar interruptions
and leaps. Koch has called attention to the fact that
by this acquired immunity of certain tracts we can
understand the remarkable distribution of cholera when
it spreads from one of the large pilgrim resorts as a
centre ; the line which the disease takes does not
correspond to all the radii, although all have undoubtedly
been brought in contact with cholera patients ; the
cholera spreads only in those directions where this
acquired immunity is wanting.

Differences in
the effect of
the first case
of cholera.

As the result of these numerous influences, varying
according to place and season, variations in the epidemic
spread of cholera are the more readily produced because
the disease is not always carried from one individual to
another, but often attacks a large number of individuals
at the same time. Hence the differences in the effect
in cases where the chances in favour of its spread are
plentiful, and in those where they are few, are still
more strikingly manifested. "We have only to consider
how completely different the mode of spread is according
to the circumstances under which the first case of
cholera is introduced into a town. In the one place the
patient may be nursed in a well-to-do family, or in a
suitably arranged hospital with trained nurses ; in the
other place the first case may occur in a narrow, poor

SPIRILLUM CHOLER-E ASIATICS. 463

quarter of tlie town where numerous individuals come
in contact with the patient and with the dejecta, where
the methods of cleanliness are by no means sufficient,
where the food is prepared and eaten in the same room,
where there are numbers of flies which aid in the
transport of the germs, and where consequently it is
only rarely that direct contamination does not take
place. It is evident that in the latter case the chances
of a sudden and great extension of the disease are
present, and hence the effect is so very different from
that of the former case, in which at most only an
isolated further infection occurs.

If now the disease has attacked several individuals Difference due

. . , ,. , . tothesucceed-

these unequal chances continue to act in an increasing ing cases.
degree, because from every new case where the chances
continue favourable there is a marked multiplication of
the number of individuals affected, and along with this
an enormous increase in the number of sources of
infection. In the one town the primitive arrangements
for the removal of faeces, badly constructed wells, small
dwellings, poverty of the population, bad nutritive con-
ditions, &c., can readily so act that almost every new
case forms a source of infection and a means of trans-
port, and that susceptible individuals are constantly
present in the neighbourhood of the sick. In other
towns or at other seasons, on the contrary, a very
much smaller number of cases may occur, on account of
the presence of a drainage system, a good supply
of water, well-built houses, well-to-do, cleanly popula-
tion, or on account of the fact that the individuals in
contact with the sick are in great part insusceptible or
immune ; in this way the chances are against the further
spread of the disease, and favour the interruption in
the chain.

Circumstances which are apparently trivial and Influence of
accidental, and which readily escape observation, may tSviaintly
often exert such an influence on the spread of a cholera accident*,
epidemic that the presence of local and seasonal pre-
disposing conditions may be of absolutely no impor-
tance. Thus to mention some examples of these

464 SPIRILLUM CHOLERA ASIATICS.

accidental conditions we not uncommonly find in the
smaller towns in Mid and North Germany that the
relatively pure water flows through the streets of the
town in open gutters, and that this water is not only
employed for household purposes but also — per nefas,
but nevertheless very frequently — for carrying away the
refuse from houses. If a case of cholera occurs in the
higher portion of such a town, and if dejecta or water em-
ployed for washing the linen gain entrance to this run-
ning water a sudden extensive spread, a sort of explosive
epidemic, may be the result, whatever be the state of
matters as regards the other factors which are of im-
portance in the production of an epidemic. Koch
observed another example in Marseilles ; in that town the
market women who offered vegetables for sale were wont
to sprinkle their wares from time to time with water in
order to keep them fresh, this water being taken by
means of a broom from a gutter which ran past the
market. The comma bacilli could very readily enter
this gutter water ; and hence, by means of the infected
vegetables and fruit, the germs might be distributed to
such an extent that a violent epidemic could result. — A
similar occurrence can take place when one of the first
cholera cases occurs in a dairy, and when comma bacilli,
though only in very small numbers, enter the milk by
one of the modes described, for milk is a very excellent
soil for the growth of the cholera bacilli.

Such accidents may now and then exert an important in-
fluence on the course of the epidemic, and as it maybe very
difficult to trace them subsequently, we may have the oc-
currence of a number of so-called "inexplicable" cases.

If we review the whole series of factors which are
here mentioned, and which can influence, both as regards
place and season, the commencement and the course of
a cholera epidemic, we must admit that a local and
seasonal distribution of cholera, varying much at
different places and times, undoubtedly exists.

SPIRILLUM CHOLERA ASIATICS. 465

But even as regards the peculiar laws which seem to
govern the local and seasonal spread of the disease,
we may easily find, among the important factors
mentioned above, some which completely explain the
repeated or permanent insusceptibility of some places,
or the constant preference for a definite season of the
year.

Thus the occurrence of cholera in Germany in late Explanation

of the seasonal

summer and harvest can be explained by the presence 01 predisposition
various predisposing factors during these months. It is m Geru
during this season, as Pettenkofer has pointed out, that
the level of the ground-water is lowest, and that conse-
quently the upper layers of the soil are driest ; the exist-
ence of a definite drying zone has, as was pointed out above,
a markedly favourable influence on the preservation and
increase of the sources of infection. The cholera months
are also those in which the largest numbers of insects
are present, and these undoubtedly take part in the
transport of the germs ; they are also the months in
which people eat the greatest quantity of raw food, which
is also well suited for the transport ; but above all in
those months there is a marked individual predisposition
on the part of a relatively large portion of the population
on account of the frequent gastric disturbances, the
causes of which have been previously referred to. It is
easy to understand that where this dry zone is absent
and with it a number of sources of infection, where the
various means of transport referred to are wanting, and
where there is no wide-spread individual predisposition,
the chances for the spread of cholera are very unfavour-
able, and that therefore in our climate it does not
usually spread at all during winter and spring, or at
most only a few individuals are affected. At times,
however, in spite of the unfavourable season of the
year, some of the other predisposing factors may be
so markedly developed that an exceptional epidemic
may occur even in the middle of winter or in spring.

There are also a number of factors which explain the Explanation
extinction of an epidemic after its longer or shorter dura- tk>r>hofextm<;~
tion. In this respect one important point is, that soon epidemics.

30

466 SPIRILLUM CHOLERJE ASIATICS.

after the first appearance of the epidemic the treatment
of the individual cases is better carried out, that those
Avho are in contact with the sick take greater care as
regards cleanliness and other precautions, that the
majority of the inhabitants take less raw food, that
greater care is employed in providing pure water, that
the individual predisposition is diminished as far as
possible, partly by the avoidance of excesses, partly by
early treatment of gastric disturbances, and partly, in
the case of another portion of the population, by recovery
from a previous mild or severe attack ; and finally, that
at times, with the change of the season of the year, one
or other of the external influences are removed, and thus
the sources of infection, and the ease with which the
germs are transported, are diminished. — The more com-
pletely and quickly all those factors which tend to the
extinction of the epidemic come into play the earlier
will further infection cease; the longer the one or the
other favouring condition continues the further will the
epidemic spread. It is evident that in order that cholera
should become permanent or endemic in the neighbour-
hood other very favourable conditions must be present,
especially as regards the climate, and probably still
more as regards the habits of life of the population.

It would lead us too far to explain the various striking
phenomena which occur in the epidemic spread of cholera
by the factors which come into play, and which have
already been mentioned in detail. This much is evident,
that the sum of the external factors furnishes a sufficient
explanation of numerous epidemiological laws, and also
of numerous exceptions; whether it be that in the one
case several of these factors act together, and thus
increase the effect, or whether it be that one or other are
in opposition to, and thus neutralise each other, there
are a number of possible explanations which may corre-
spond to as many variations in the occurrence of cholera.
For many persons the extraordinary multiplicity of the
factors which furnish the explanation of the local and
seasonal distribution of cholera is self-evident; this is
more especially the case since Virchow drew attention so

SPIRILLUM CHOLERJE ASIATIC JE. 4(>7

markedly to tliis point in the proceedings of the last
cholera conference. But during the last decade the
tendency to draw up a scheme of cholera epidemics, and
the desire to find a single causal factor in explanation of
the peculiarity of its course, has come to the front so
exclusively that it seemed necessary to draw especial
attention to the multiplicity of the factors which come
into play, and to point out in detail what factors can
produce regular local and seasonal variations in cholera
epidemics, and what factors may lead to irregular and
accidental variations.

These deductions are chiefly based on the biological
peculiarities of the comma bacilli as we have learned
them from Koch's investigations, and on the assumption
that cholera is contagious, and that the contagium is
contained in the comma bacilli.

These views are, however, not as yet accepted by all views of the
cholera investigators; on the contrary, the "localistic"
view brought forward by von Pettenkofer, Cuningham, and
their followers, is opposed to this " contagionistic "
standpoint. Cuningham assumes that in order to origi- Cunin
nate a cholera epidemic it is not at all necessary that a V1
patient suffering from cholera should enter the place
where it begins, but on the contrary that cholera occurs
everywhere sporadically, and that favourable local condi-
tions are alone necessary to lead to the outbreak of an
epidemic. This peculiar view is only a possible one on
the arbitrary assumption that every case of violent
diarrhoea is a case of true Asiatic cholera. This view
was not easy to upset in any individual case so long as
we had only symptomatic and pathological anatomical
differences to enable us to distinguish between cholera
asiatica and cholera nostras; it is, however, quite un-
tenable, since we have found a marked difference between
the two diseases, in that the characteristic cholera bacilli
are always present in the one and never occur in the
other.

468 SPIRILLUM CHOLERA ASIATICS.

Von Pettenko- Von Pettenkofer admits that in the case of cholera
s view. we |iave f.0 do wj^ a virus which is carried from place
to place, but he lays chief stress on the facts as to the
peculiar local and seasonal distribution of cholera, and
he assumes that in addition to the virus introduced,
other factors, dependent on the locality, must come into
play in order that an epidemic should occur. If we
call the virus which proceeds from the patients " x,"
and the something due to the locality " y" cholera only
spreads when x and y occur together ; x alone can only
quite exceptionally cause a single case of the disease,
but never an epidemic. On the contrary, in a place
where y is absent we may swallow cholera dejecta with-
out any harm ; while an infection would follow under
these circumstances if y was present in the same
locality.

Pettenkofer has attempted to ascertain the nature of
;/ by an accurate investigation of the local and seasonal
distribution of a large number of cholera epidemics, and
he has come to the conclusion that the nature of y is a
certain character of the upper layers of the soil. A soil
which predisposes to the disease must be porous and
penetrable by air and water, it must be contaminated
with dejecta, organic substances, &c., and it must be to
a certain extent moist. The moisture of the soil is the
factor which chiefly varies with the season ; too great
moisture diminishes the predisposition in the same
manner as too great drought. The degree of moisture
of the soil is in the majority of cases most accurately
shown by the variations in the level of the ground-water,
in other cases it is better determined by the amount of
rainfall.

Hence those localities are permanently immune where
the ground is composed of rock or dense clay, also those
where the soil is quite clean, and those where the sur-
face of the soil is always either very dry or very moist.
A temporary immunity is occasioned chiefly by too
great or too little moisture of the soil.

According to Pettenkofer' s view the relation between
the virus x and the factor y, which depends on the pre^-

SPIRILLUM CHOLERA ASIATICS. 469

disposition of the soil, is either that y so prepares man
that he becomes susceptible for x, or that x is altered
under the influence of the y properties of the soil, and
is only then capable of producing infection in man.
Pettenkofer looks on the latter alternative as the
most probable, and he is also of opinion that # is a
species of bacterium, the development or distribution
of which is much influenced by these y properties of
the soil.

Pettenkofer holds that Koch's comma bacillus is not Pettenkofer '*
the proper x, because its characters show that it cannot the comma t0
be favourably influenced by the y properties of the soil ;
the comma bacillus dies as the result of drying, while a
relatively dry soil furnishes the best seasonal predis-
position for cholera. The comma bacillus further rapidly
dies in putrefying substrata, while a soil contaminated
with dejecta is one of the predisposing factors in favour
of cholera. — Neither of these objections are, however,
valid. Where the moisture of the soil diminishes the
degree of dryness is almost never such that the comma
bacilli which reach the soil must at once die. On the
contrary, the conditions for the spread of the infection
are, as was shown on p. 457, more favourable under these
circumstances. In like manner the rapid destruction
of comma bacilli in putrefying substrata has reference
to their behaviour in fluids where there is active multi-
plication of saprophytes, but does not apply to the soil
in which the multiplication and hurtful influence of the
saprophytes are practically of no moment. — It is, there-
fore, evident that Pettenkofer 's opposition to the comma
bacillus is in reality not at all justified ; while the fact
of the constant and exclusive occurrence of the comma
bacilli in cholera has led him to the assumption, which
certainly does not seem by any means probable, that the
virus of cholera is an organism as yet unknown, that
this virus becomes altered in an as yet unknown
manner under the influence of a porous, impure, and
somewhat moist soil, and can then cause the infection,
and that after the occurrence of infection the vibriones,
which are present in small numbers in the intestine,

470 SPIRILLUM CHOLERJ2 ASIATICS.

become transformed into the enormously multiplying
comma bacilli.

The peculiarities of the local and seasonal distribu-
tion of cholera are undoubtedly facts which we must all
recognise. Pettenkofer 's observation that the condition
of the superficial layers of the soil frequently plays a
causal part in these peculiarities is likewise undoubtedly
correct ; but it has been previously shown that this con-
dition of the soil can exert an important influence, even
though we admit the etiological significance of the
comma bacillus. But also to an unbiased mind it is
evident that the nature of the soil, to which Pettenkofer
gives such prominence, is by no means of itself suffi-
cient to explain all the peculiarities in the spread of the
epidemics. There is no doubt that Pettenkofer's ex-
planation is not applicable in many cases; that, for ex-
ample, cholera epidemics in the eastern part of Prussia
have occurred on dense clayey soil, and in Bombay on
non-porous rock, while, on the other hand, porous soils
have been passed over. We must at all events regard
Pettenkofer's views only as hypotheses, and must not
ascribe to them the value of a firmly established theory,
which must be used as a basis on which to test the
results of present and future investigations. We must,
on the contrary, admit the possibility that numerous
other causes come into play in the peculiar mode of
spread of the epidemics, and we can only take the
proper course if we also take into account the other
possible explanations. If we base our investigations on
the known biological characters of the comma bacillus,
we are at all events on firmer ground, and are more
likely to find out the truth than if we stubbornly hold
to the view of an unknown x, and a still more un-
known y.

Prophylactic The practical prophylactic measures to be taken

regulations against cholera differ also in an important manner

against x

cholera. according as the localistic or the contagionistic view is

SPIRILLUM CHOLERA ASIATICS . 471

the one held. The localists throw aside all quarantine
regulations, all arrangements in order to afford protec-
tion against infection, and all disinfection ; on the other
hand they pay special attention to the diminution of
the y properties of the soil, of which the contamination
of the soil is that which is most easily avoided and
altered ; drainage, or a proper method of removing the
sewage, is supposed to lead to such a condition of the
soil that it is no longer suitable for the epidemic spread
of cholera.

From the standpoint of the contagionists all the
measures discussed ahove which can protect the indi-
vidual from infection are of the first importance. Hence
the prevention of the introduction of the disease is the
first protection against an epidemic of cholera. As
cholera is generally brought to us over the sea from
India by patients suffering from the disease a strict
medical inspection of ships coming from India in the
Suez Canal is of immense importance. It is only in
sea-port towns that any good result can be hoped from
quarantine. If cholera has once broken out on the
Continent nothing more can be expected from quaran-
tine regulations. In that case each town must take
care above all that the first case of cholera is quickly
brought to the notice of the authorities, and is diagnosed
with certainty. The latter can be almost always done
by means of plate cultivations, and the sanitary autho-
rities must therefore know how to make them. A great
deal also depends on proper treatment of the first case
or cases. These should be nursed wherever possible in
hospitals, or at any rate by trained nurses ; the linen
and clothes of the patient should be disinfected with
steam in an institution for the purpose which should be
present in every town ; the dejecta should be rendered
innocuous, and all other suspicious substances should
be disinfected with carbolic acid, sublimate, or concen-
trated hydrochloric acid ; the sick-rooms are most
readily freed from infective germs by opening the
window, and shutting up and heating the room for
some days ; in this way the comma bacilli will be

472

SPIRILLUM CHOLER/E ASIATICS.

killed by drying. The population should also be
instructed as to the circumstances which favour or
hinder infection, more especially as to the influence
of careful cleanliness, as to care in preparation of the
food and in the selection of drinking water, and as to
the hurtful influence of excesses and of even the mildest
gastric disturbances. Drainage, proper removal of
waste materials, and a good water supply, are also,
from the contagionistic point of view, excellent prophy-
lactic measures for a town, the basis of these regulations
being, however, somewhat different from that of the
localists ; the chief advantage of these arrangements is
not that they lead to cleansing of the soil from putre-
fying materials, or freeing of it from materials which
could nourish the lower organisms, but it is the prompt
removal of the infective agents, and the diminution of
the opportunities for infection.

Morphological
characters.

Spirillum Finkler and Prior.
(Vibrio proteus.)

From the dejecta of patients suffering from cholera
nostras which had been kept for some time, Finkler
and Prior isolated a spirillum which resembles the
comma bacillus of Asiatic cholera, but can nevertheless
^ be very readily distinguished
from it, more especially by
means of a number of dif-
ferences in its mode of
growth.

As a rule the individual
curved bacilli, which when
united together form the
spirilla, are the chief forms
present. The curved bacilli
are somewhat longer and thicker than Koch's comma
bacilli ; their thickness is not so regular as the latter,
but on the contrary they appear oftener somewhat pointed
at the ends, and thicker in the middle. Not uncommonly

Fig. 124.— Spirillum of Fiuklcr
and Prior X 700.

SPIRILLUM FINKLER AND PRIOR, 473

we find " S " forms similar to those of the cholera bacillus,
and also longer screw-like threads, which, however, do
not occur so frequently in gelatine cultivations, and do
not show so many twists as in similar cultivations of the
cholera bacilli. When examined in drop cultivations
they show active movement.

According to Buclmer, Finkler's bacilli have a great Involution
tendency to alter their form when the state of the °
nutrient medium is unfavourable (Buchner has there-
fore proposed to give the bacillus the name Vibrio
proteus). Under these circumstances they form some-
times spheres, sometimes spindles, and sometimes
monad-like bodies ; the latter may present an oval
form as much as 4 p.. in breadth, or may appear as
large spheres, or as very broad and fat portions of
twisted threads, and they are obtained very easily by the
addition of 5 per cent, of sugar, or 2 per cent, of
glycerine, to the gelatine. These structures can only
be looked on as pathological or involution forms.

On gelatine plates Finkler's bacilli form after 24 Cultivation*
hours white points, which under a low power present
the appearance of circular yellow or yellowish-brown
discs ; in contrast to the young colonies of Koch's
comma bacilli the outline of Finkler's colonies is very
sharp, dark, and almost absolutely circular, while in the
case of the cholera bacilli a wavy irregular outline is
observed ; the colour is also distinctly darker, and the
surface does not present such
a highly refracting, granular
appearance as in the case of

the true cholera colonies. a o

Liquefaction of the gelatine Fig. 125.— Colonies of Finkler

, . , and Prior's spirilla X 80.

begins very early : as soon .,

0 . J J . », after 16 hours.

as this occurs the outline of *, „ 24 ,,

the colonies loses its sharp-
ness, the periphery often appears dentate or as if
eaten away, while, on the other hand, the external
zone of liquefaction has a sharp border. One can
often observe at this stage zones of different colour
in the colony ; a darker central zone, then a lighter,

474

SPIRILLUM FIXKLER AND PEIOR.

Puncture
cultivations.

Growth on
potatoes.

and then again a darker marginal zone. The young
colonies can be distinguished from those of cholera
bacilli without any difficulty by means of the above
mentioned characters ; at a later stage, more especially
when the cholera colonies are older than Tinkler's, the
diagnosis is not so easy, but it can always be made when
a considerable number of colonies are examined. — At a
still later period Tinkler's bacilli liquefy the gelatine
very energetically ; a funnel, 1 cm. in diameter or
more, is formed, and as a rule the whole plate very
soon becomes entirely liquid.

In puncture cultivations in gelatine Tinkler's bacilli
arc also characterised by the greater energy with which

they liquefy the gelatine.
When cultivated under the
same conditions as Koch's
bacilli they lead, even with-
in 48 hours, to the forma-
tion of a comparatively wide
sac-like tube which is filled
with muddy fluid ; after 24
hours more the liquefaction
has usually reached the wall
of the test-tube and has in-
volved the uppermost por-
tion of the gelatine, while
the lower end of the sac has
correspondingly increased
in breadth. — When culti-
Fig-i2&~C'Ultivatio\of.^inklcr vatedou nutrient agar the

and Prior s comma bacillus. . °

c, 2 days old. d, 4 days old. bacilli form yellowish-white

deposits without liquefac-
tion, and without any definite characters. Blood serum
is rapidly liquefied. — On potatoes kept at the tem-
perature of the room they form within 48 hours a
greyish-yellow gelatinous coating, which is marked oft'
from the substance of the potato by a white border.
This growth on potatoes forms the most striking con-
trast to the behaviour of Koch's comma bacilli, which do
not grow at all on potatoes at the ordinary tempera-

SPIRILLUM TINKLER AND PRIOR. 475

ture, and at higher temperatures only give rise to a thin
brown coating.

In all the cultivations of Finkler's spirilla a some-
what foul smell is developed. In nutrient substrata
containing sugar, fermentation and the formation of
acid take place, according to Buchner. — Finkler's bacilli
seem, according to the experiments made by Finlder
and Prior, to be much more resistant towards drying
and overgrowth by other saprophytes than the cholera
bacilli. A cultivation which had been dried and kept for
two months over phosphoric acid free from water grew
when planted on fresh nutrient substrata.

If a pure cultivation of Finkler's bacilli is injected Experiment
directly into the duodenum of guinea-pigs a certain on ammals-
proportion (3 out of 10) die according to Finkler and
Prior and numerous bacilli are found in the intestinal
contents, having apparently multiplied there ; Koch's
control experiments also showed that about 30 per cent,
of the guinea-pigs which had previously received soda
solution and tincture of opium, as in the experiments
with cholera cultivations mentioned above, died after the
administration of cultivations of Finkler's bacilli by the
mouth. — Injection of considerable quantities of cultiva-
tions, either subcutaneously, into the veins, or into the
stomach, set up no disease in the animals experimented
on. Pathogenic action seemed only to occur under such
complex conditions, and then only so rarely that, as the
result of the experiments on animals alone, Finkler's
spirilla must be reckoned among the saprophytes.

It is still doubtful, however, whether these organisms Habitat of
play a pathogenic role in man (this would be quite con-
ceivable when we bear in mind the similar though much
more aggressive behaviour of Koch's bacilli on animals),
and whether they stand in any etiological relation to
cholera nostras. Finkler and Prior state that they
found the same spirilla on microscopical examination in
five cases of cholera nostras; nevertheless these organisms
could not be recognised with certainty by other observers,
and more especially by Koch, in Finkler and Prior's
preparations. Finkler and Prior have only isolated

476 SPIRILLUM FINKLER AND PRIOR.

these organisms by cultivation (a plan that is necessary
in order to render their identity certain) in the case of
dejecta from cholera nostras which had been kept for a
long time, and which had undergone putrefaction. —
Other authors have, however, sought in vain for
Finkler's bacilli in a large number of cases of cholera
nostras. Thus Koch examined a considerable number
of cases, and among them several which ended fatally,
with negative results ; and investigations by Ermengem,
Watson Cheyne, Biedert, and others, have in like manner
yielded negative results.

On the other hand, Miller has found curved bacilli in
a hollow tooth, and these must be looked on as identical
with Finkler's, from their microscopic characters, and
their behaviour on cultivation and on animals; and
Kuisl* has obtained Finkler's spirilla in a nutrient
solution containing peptone, meat infusion, and 2 per
cent, of potash soap, from the contents of the caecum of
a patient who had committed suicide.

Hence from the mode of distribution of these bacilli
we cannot find any evidence of pathogenic properties,
nor any relation to cholera nostras, and they must
therefore be reckoned among the saprophytes till better
evidence of their pathogenic character has been fur-
nished.

From Finkler and Prior's first publications, in which they
held that their bacilli were identical with Koch's comma
bacilli, it is evident that they made their experiments at that
time in complete ignorance of the usual and necessary methods
of cultivating and isolating bacteria ; and in their paper
they also speak of a mode of development of their bacilli in
which "alternation of generation," "mother cells" which
burst at a later period, " spore bearers," &c., play a part,
and which has no analogy in the developmental history of
other bacteria. In their last communication,t it is true,
these authors give a very detailed description of Koch's
method of investigation, with which they have apparently
become acquainted subsequently; but they attempt to bolster
up their former standpoint with only slight modifications, and

* Munch, iirztl. Intelligenzbl, 1885, 36.

f Centralblf. allg. Ges, Ergfinzungshefte, vol. i., Parts 5 and 6.

SPIRILLUM TYROGENUM. 477

to defend, without any new and better reason, those original
expressions which they hare introduced into the science of
bacteriology.

Spirillu m tyrogcnum.
(Cheese spirilla.)

These organisms were isolated by Deneke in the
iiuthor's laboratory from cheese which had been kept for
a long time ; morphologically and on cultivation they
show a greater resemblance to Koch's comma bacilli than
do Finkler's spirilla, but like the latter they can be
definitely distinguished from the cholera bacilli by
certain culture characteristics.

The individual bacilli are somewhat smaller than Morphologic*
Koch's bacilli, and often show very long spirillar threads el
with somewhat narrower twists and smaller screws. In
drop cultivations they show active movements.

On gelatine plates the youngest colonies form small Cultivation*,
white points after 24 hours, and under a low power they
present the form of circular discs with sharp outlines,

. </ ""-- Fig. 128.— Colonies of cheese
1 ^X> spirilla X 80.

^r- a, after 16 hours.

Fig. 127.— Cheese spirilla &, „ 24 „

X 700. c, „ 36 „

and of a dark, greenish-brown colour. At a later period
the margin appears somewhat lighter, the centre of a
dark yellow colour ; at the same time liquefaction of the
gelatine commences, and the sharp outline of the colony
not uncommonly disappears. The liquefaction of the
gelatine is more energetic than in the case of the cholera
bacilli, but does not occur so quickly as in Tinkler's.
This fact is seen also in puncture cultivations, where a
sac-like liquefied tube is formed within 24 hours, and at
a later period there is complete liquefaction of the

478 SPIRILLUM SPUTIGENUM.

gelatine. On agar the cheese spirilla form a yellowish-
white layer ; they liquefy blood serum energetically.
No growth takes place on potatoes, either at the or-
dinary temperature or at higher temperatures.
Experiments By the ordinary modes of application no pathogenic

011 animals. , • • . -T -IT .

action is exerted on animals, in two experiments in
which the cheese spirilla were injected directly into the
duodenum of guinea-pigs Deneke observed no morbid
phenomena. Of fifteen guinea-pigs which were treated
by Koch in the same manner as in his experiments with
cholera bacilli, by previous introduction of soda solution
and tincture of opium, and then of pure cultivations of
these spirilla, three died. — From these results, as well
as from the habitat of the spirilla, we must regard this
species of bacterium as a pure saprophyte.

Deneke's experiments on animals were limited to one
experiment on six guinea-pigs ; into two of these cholera-
spirilla, into two Finkler's spirilla, and into two the cheese
spirilla were injected into the duodenum. The two first
animals died, the other four remained alive. It may be
remarked here, in answer to an objection by Finkler, that
these experiments on animals were not done on a larger scale
because the author knew that the same experiments were
being carried out at the same time in larger numbers in
Koch's laboratory, and because in the case of the cholera
bacilli more especially the results of Nicati and Bietsch and
of Ermengem had already been published. The result of this
comparative experiment permitted a judgment as to the
pathogenic or saprophytic nature of Finkler's and Deneke's
spirilla, so much the more readily because all attempts to
injure animals by these bacteria by the ordinary modes of
infection failed, and because in this case the habitat and mode
of spread of the organisms did not, as in the case of the
cholera organisms, point to a pathogenic rule which required
to be still further confirmed by experiments on animals.

Spirillum sputigenum.

Curved bacilli In the deposit on the teeth and in the saliva of man

mouth116 curved bacilli not uncommonly occur which have a certain

resemblance to the cholera bacilli, but are somewhat

larger, thinner, and more pointed at the ends. Where

the staining with aniline dyes is not too dark, it can also

SPIRILLUM (SPIROCILETE) OBERMEIERI.

479

be seen that the colouring matter is irregularly distri-
buted in the rod, being less plentiful at the ends. Lewis*
has nevertheless held that these
organisms are identical with cholera
bacilli; but they differ very dis-
tinctly from these, in that the
spirilla of the saliva cannot be
cultivated by any of the ordinary
methods of cultivation. Hence
the isolation of these bacteria and the study of their
characters has not as yet been possible.

Fig. 129.— Spirillum
srmtigenum (after
Ermengem) X 700.

They grow on
none of the
ordinary
nutrient sub-
strata.

Spirillum (Spirocliczte) Olermeicri.

These organisms were first observed by Obermeier in Spirilla of
the blood of patients suffering from relapsing fever, fever8™1
They have the form of long, wavy, flexile threads, with
10 to 20 convolutions ; their length varies between 16
and 40 /*., their breadth is from | to £ that of the comma
bacilli. In fresh preparations the spirilla are seen to be
motile ; they move quickly, and
also show undulatory movements,
which pass in a wavy manner
through the whole length of the
thread. Colouring matters, more
especially fuchsine, alkaline methy-
lene blue, and Bismarck brown, are
comparatively readily taken up;
nevertheless, on account of their
fineness, it is only possible to dis-
cover these spirilla, when present in small numbers,
with high powers, and good illumination. Larger
numbers of the bacilli, which in many cases fill the
blood, are on the other hand readily recognised, both
in fresh and in stained preparations.

The spirilla are found exclusively in the blood of the Occurrence.
patients, never in the secreta; further, they are only
present during the febrile attack, but not in the interval
between the attacks, or at most only for two days after

* Lancet, 183 i, 20 Sept.

Fig. 130.— Spirilla of
relapsing fever in
blood X 500.

480 SPIRILLUM (SPIROCH/ETE) OBERMEIERI.

the attack of fever. Their numbers vary very greatly.
Outside the body, when kept in blood serum or in -?> per
cent, salt solution, the spirilla retain their movement
for a considerable time; but as yet we have not succeeded
in obtaining any decided multiplication in any sort of
nutrient substratum, nor can a cultivation be carried on
through several generations.

Inoculation of On the other hand the disease, characterised by its
a^acks of fever and by the appearance of the spirilla, can
be inoculated on monkeys, by means of human blood
containing spirilla. Koch and Carter were able, in the
case of long-tailed macaques, to set up a typical attack
of fever by subcutaneous injection of a small quantity of
defibrinated blood, containing spirilla, after an incuba-
tion period of several days; during the attack of fever
the blood showed large numbers of spirilla, while the
organisms were never found either before or after the
appearance of the fever. Numerous spirilla could also
be demonstrated in the organs of the animals killed at
the height of the febrile attack. True relapses, such as
are characteristic in man, did not occur in monkeys; the
most that took place was that, a few days after the crisis,
the temperature was again for a short time elevated, but
without any appearance of the spirochiete in the blood.—
The disease can be inoculated from one monkey to
another, but only by means of blood containing spirilla.
Monkeys are not protected from recurrence by one attack
of the disease : Koch and Carter were able to set up the
same typical attack of fever when the monkeys which had
recovered from the first attack were inoculated again, after
some days or weeks, with blood containing the spirilla.

From the constant and exclusive occurrence of these
peculiarly-shaped bacteria in relapsing fever, and from
the fact that the disease can only be set up in healthy
monkeys by blood which contains these spirilla in the
living condition, we may with certainty conclude that the
spirilla are the causal agents of this disease, even although
we have not as yet succeeded in cultivating the organisms,
and in studying their characters more minutely.

SPIRILLUM (SPIROCH^ETE) OBERMEIERI. 481

All the other spirilla are as yet very incompletely incompletely
known, and we do not possess methods of cultivating
them in a state of purity, and of observing their mode of
development. They appear to grow by preference on
fluid substrata, and to accumulate more especially at the
surface ; a situation in which they are usually found in
enormous numbers is in the ordinary cesspools (Miihl-
hauser). Besting forms have not as yet been described
with certainty in the majority of the species which have
been observed, the only exception being spirillum rugula;
but it is possible that at a future period spore-like struc-
tures will be found in other of the bacteria belongiDg to
this almost unknown class.

Geddes and Ewart* state that they have observed the
following facts as regards the mode of development and spore
formation of spirilla; the spirilla have alternately a motile
:ind a resting stage ; they ultimately grow in the form of a
small thread without any definite coils ; this thread becomes
longer and thicker, and spores appear in it. These spores
divide rapidly and become glistening and brown, while the
threads become again motile and break up sooner or later.
The spores thus liberated become encysted, and divide into a
number of capsules which become motile after a period of
rest ; the " sporulas " contained in the capsules escape, sprout
in a comma form, and soon grow to the ordinary spirillum. —
These observations have evidently not been made on pure
cultivations, and are of no value.

The following are the spirilla which have as yet been
distinguished from one another, but which require more
accurate study: —

Spirochate plicatilis. — Threads thin with numerous
narrow turns, 110 to
*225 fi. in length. As
a rule the threads form
a double wavy line ;
the primary turns are
of the same size in all A

the examples; the se- ^ Spiroch{fite pu^gu^^ in its*elgh.

COndary turns are bourhood vibrio rugula (a) and other

», , . bacteria.

Otten Unequal in Size. B, Spirochsete from the teeth X 500.

The ends are blunt. The organism moves with extreme

* Proc. of the Roy. Soc.t vol. 27, p. 481.

81

482

SPIRILLUM RUGULA.

rapidity. — It occurs frequently during the summer in
marsh water in which algae are putrefying, in gutters,
&e.»

SpirocJuete denticola (Spirochaete of the saliva). —
These organisms are much shorter than the foregoing,
as a rule 10 to 20 /*. in length ; the threads have a
simple wavy outline, and are pointed at hoth ends. It
occurs very frequently in the deposit on the teeth, and
along with Leptothrix buccalis in the contents of carious
teeth, t

Spirillum rugula (Vihrio rugula). — Cells 6 to 8 ft.
in length, *5 to 2'5 p. in thickness, with a single bend,
or at most with flat spiral turns ; at times united in
longer chains, often matted together in considerable
numbers (fig. 55A). They are motile, with active
rotation around their long axis. Koch has observed
distinct flagella. Before spore formation takes place

Fig. 132.— Vibrio rugula (after Prazmo\v>ki) X 1020.
«, young rods. b, thicker rods. r, spore-bearing rods.

the threads become thickened throughout their whole
length ; a spherical swelling then occurs at one end, so
that the rod has the appearance of a comma; this swell-
ing ultimately becomes a spherical spore. — The
organism occurs in marsh water, in the deposit on the
teeth, in feces, &c. It is often associated with bacillus
butyricus, and is hence in all probability an anaerobe.
According to Prazmowski'i Vibrio rugula occasions
energetic decomposition of cellulose. In decoctions

* Koch, Colitis Beitr. z. Blol. d. Pflanzen, ii., p. 420.

f Ibid., p. 432.

j Untersuchunyen, &c., Leipzig, 1880, p. 44.

SPIRILLUM VOLUTANS. 483

made from vegetable tissues (portions of potato, &c.),
Prazmowski was able to observe that the rods of Vibrio
rugula collected around the cell walls of the tissue, and
that they broke up in a short time (3 or 4 days) into
swarms of Vibrio rugula. The intimate nature of the
fermentative action has not as yet been ascertained.

Spirillum serpens ( Vibrio serpens). — Threads thinner,
3 to 4 regular and permanent bends, 11 to 28 /*. in
length, "8 to I'l /*. in thickness ; at times united in
chains. Actively motile ; often in dense masses. — Occurs
frequently in various stagnant fluids.

B C '

Fig. 133.

A, Spirillum (vibrio) serpens. 7?, Spirillum tenue.

C, Spirillum undula X 650.

Spirillum tenue. — Threads very thin, at least 1J turns
of a screw, at most, however, 2 to 5 ; the space
between the individual turns is from 2 to 3 /*., the
length of the spirilla being therefore 4 to 15 /*. ; they
move with lightning rapidity. It often occurs in dense
masses in decoctions of plants.

Spirillum undula. — Threads 1'] to 1'4 /*. in thickness,
8 to 12 p.. in length, turns wider, 4 to 5 /*. in height.
Each thread has li to 3 turns. Kapid simultaneously
turning and shooting movements ; a flagellum can be
distinctly seen at each end in the form of a long,
slightly arched, and powerful thread, becoming thinner
towards its end. — It occurs in the most various kinds of
putrefying fluids.

Spirillum rolutans. — Threads, 1'5 to 2 /*. in thick-
ness, 25 to 30 p. in length, somewhat thinner and
rounded at the ends, with thick, dark, granular contents.
Each thread has 2J to 3^ turns, the interval being thus
from 9 to 13 p. Sometimes motile, sometimes non-
motile ; a distinct flagellum at each end. — It occurs in
marsh water, and it has been foun 1 in a decoction of
dead fresh-water snails.

484 FISSION FUNGI WITH VARIABLE VEGETATIVE FORMS.

Spirillum sanguineum (Ophidomoiias sanguinea) (according
to Zopf belongs to the Beggiatoa, see page 488). — Threads
3 p. or more in thickness, with 2 to 2^ turns, 9 to 12 n. in
width. A flagellum at each end. The spirals, which have a
reddish shimmer, present a dark granular appearance, owing
to the presence of numerous highly refracting reddish
granules. Found by Warming and Cohn in putrefying
brackish water. In such water, which occurs in harvest in

Fig. 134.— (After Cohn.)

A, Spirillum volutans X 650.

B, Spirillum sanguineum (Ophidomonas sang.) X 600.

many lakes on the Danish coast, and in which many alga? and
salt water phanerogams decompose with the simultaneous
appearance of red patches and masses, Warming found some
other forms of spirilla, which as a rule contained granules of
sulphur in their cell contents, and which he distinguished
under the names Spirillum violaceum, Rosenbergii, atteima-
tum, &c.*

Spirillum leucomelsenum. — A form of rare occurrence
(observed in water on the top of decomposing algas), but which
is noteworthy from the fact that alternate black and clear
spaces occur in the spirillum, occasioned by the accumulation
in the interior of the rod of dark granular substances at
regular intervals. f

IY. FISSION FUNGI WITH VARIABLE VEGETATIVE
FORMS.

A considerable variation in form lias been recently
demonstrated by Zopf 's investigations in the case of the

* Warming, Videnskabellge Meddeddser fra den naturhist. Fwening i
Kfobenhavn, 1875, p. 398.— Cohn, Beitrage, vol. i., Part 3, S. 169.
f Kooh, Mitth. a. d. Ges. Ami., i., p. 48.

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Young microscopical colonies with irregula
They liquefy the gelatine slowly.
They form a brownish deposit on potatoes b
of at least 30° C.

Young microscopical colonies, circular, wii
yellow.
They liquefy the gelatine energetically.
They form a greyish yellow layer on potato

Young microscopical colonies, circular, with
They liquefy the gelatine energetically.
They do not grow on potatoes.

Curved bacilli, somewhat larger than Spiri
in healthv human saliva

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8 — 12 /*. in length, 1^ — 3 turns, about T25 \
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486 FISSION FUNGI WITH VARIABLE VEGETATIVE FORMS.

organisms arranged together in the following pages,
these organisms differing from the bacteria as yet
described in their natural habitat, in their size, in their
morphological characters, and in many biological
characters; these organisms were, up till a few years
ago, reckoned by most authors among the algse. Zopfs
results are reproduced here without any commentary,
although they have not as yet been confirmed by control
investigations. A repetition of his observations is,
however, so much the more desirable, as the methods
employed offer no sort of guarantee that he was dealing
with trustworthy pure cultivations, and also as the mode
in which the various vegetative forms of each variety are
designated does not always appear to be sufficiently well
founded.

To this group belong the organisms included in
groups 3 and 4 of Zopfs classification, the leptothrix
and the cladothrix forms. In the series of leptothrix
varieties, the genus leptothrix has been omitted here for
the reasons mentioned on page 180, so that the genera
crenothrix, beggiatoa, phragmidiothrix, and cladothrix
are alone described. For the generic characters see
page 180.

Crenothrix Kulmia n a .

Crenothrix. This organism was discovered by Kulm, and has been
investigated by Cohn, and later by Zopf. It is one of
the most frequent aquatic fungi, and occurs in stagnant
and flowing water ; it is sometimes present in such
large quantities in the water pipes in many places
(Berlin, Lille) that the water is quite unfit for use. It
can be artificially cultivated in decoctions of dead algae,
or in decoctions of animal substances, such as swine's
bladder.

Morphological According to Zopf the fungus shows coccus, rod, and
ehaiacters. tliread forms. The cocci are spheres 1 to 6 ^ in
diameter ; their membrane becomes gelatinous, and
they multiply by fission. By this mode of multiplica-
tion, and by the gelatinous character of their membrane,

CREXOTHRIX KUHNIANA.

437

irregular masses of zooglsea of very various sizes are
formed ; these masses often form very large clumps, and
may have a red, green, or brownish-black colour, from
the deposit in them of oxide of iron. When cultivated
in marsh water
the cocci grow
to form rods,
which again
form threads by
continued fis-
sion, these
threads project-
ing from the
surface of the
zooglaea mass in
all directions.
At a certain
stage they show
u distinct forma-
tion of sheaths,
and the oxide
of iron is often
deposited in
these sheaths.
Within the
sheaths the rods
continue to di-
vide transverse-
ly, and isodia-
metric pieces
are formed which
become rounded
at the ends and
then represent
the cocci, which
are, as a rule,
fairly large (ma-
crococci). In the broad threads, however, the transverse
division ma}T go still further, so that the isodia metric
portions are split up into quite small cylindrical

Fig. 135.— Crenothrix Kiihniana X 600.

Thread forms with cylindrical discs and
(a) cocci. (After Zopf.)

488 FISSION FUNGI WITH VARIABLE VEGETATIVE FORMS.

plates. In the latter longitudinal divisions appear
usually parallel to the axis of the thread, and thus each
cylindrical plate becomes broken up into two or four
small cocci. In these crenothrix threads, therefore, the
individual joints divide in two or three planes.

By continued elongation and division of the segment
within the sheath so much pressure is brought to bear
on the apex of the sheath that it opens at that point
and permits the escape of the rods or cocci. It some-
times happens that the sheath becomes gelatinous at an
early stage, and the cocci and rods remain in this
gelatinous substance. In that case they sprout and
burst through the gelatinous sheath, forming rods and
threads, and thus the original thread has numerous
secondary threads projecting from it like a brush.

Very little is known as to the physiological characters
of the fungus ; it requires oxygen for its vegetation, and,
as the result of the presence of the gelatinous sheath, it
is very resistant to variations of temperature.

Beggiatoa.

These organisms occur everywhere in stagnant and
flowing impure waters, in sulphur springs, and in a
part of the bay at Kiel ; the organism forms milk-
white, grey, red, or violet deposits on the mud, or
on animal and vegetable bodies. It may be artificially
cultivated in infusions of animal tissues, or of algae,
with marsh water. The fully formed threads (the free
threads only represent fragments of complete threads)
show a distinct contrast between their base and apex,
in that they gradually increase in breadth towards
the apex, and at the lower part show a distinct trans-
verse segmentation. Spiral threads and fragments are
also formed under certain nutrient conditions ; the
latter pass, under certain circumstances, into a swarm-
ing stage. In the cells of beggiatoa sulphur is present
in the form of highly refracting granules with dark
outlines. The fungus is able to break up sulphur com-
pounds, more especially sulphate of soda, and to cause

BEGGIATOA,

489

the development of sulphuretted hydrogen ; as a result,
water in which these fungi are developing readily
becomes uninhabitable by
fish. The beggiatoa are
but little sensitive to the
influence of temperature,
and they can develop lux-
uriantly even at 55° C. —
Zopf distinguishes the fol-
lowing varieties : —

Beggiatoa alba. — This is the
most widely distributed va-
riety. It occurs more especi-
ally in the waste water of sugar
factories, of tanneries, and in
sulphur wells (baregine or
glair ine). The threads grow
on putrefying plants, dead
insects, &c. ; they vary in
thickness between 1 and 5 ju.
Sulphur particles are not
always present. On examin-
ing the threads, with or with-
out the action of reagents, it
can be seen that they are
segmented into long or short
rods or cocci. In the thicker
threads a further subdivision
of the cocci can be observed.
Under certain conditions of
nutrition the cocci pass into
a swarming stage. After some
time they again come to rest,
and become attached to algae,
&c., multiply by continued
fission, and form irregular
xooglaea. Under certain con-
ditions they grow and form

rods which may likewise have

. *
a swarming stage; when these

rods come to rest they grow to

form threads. Further, the

• T -ir» -II

threads may partially or wholly assume a spiral form, and the nas).

pieces of the spiral which become free may, under certain con-
ditions, swarm, their movement being caused by the presence

Beggiatoa
alba.

Morphologica
characters.

Fig; 136.— Beggiatoa alba X 540.

Group of attached threads.
(After Zopf.)

490 FISSION FUNGI WITH VARIABLE VEGETATIVE FORMS.

Beggiatoa

rosep-

persicina.

Identical with
the species
formerly de-
scribed as
Clathrocystis
roseo-
persicina.

Beggiatoa
inirabilis.

of cilia at each end. These swarming spirals were formerly
described as ophidomonas (see page 484). The spiral threads
show the same division into rods and cocci as the straight
threads, but this is more difficult to demonstrate, and can only
be done by the aid of reagents.

Beggiatoa roseo-persicina. — Frequent in impure ditches and
ponds, covering the substratum with a red or violet deposit.
Often observed on the Danish sea-coast. In the thread stage
it can only be distinguished from B. alba by the reddish- violet
colour. The cocci formed in the threads develop by con-
tinuous subdivision into peculiar zooglaea, which are lobulated,
branched, or in the form of a network. Eods develop under
certain circumstances from the cocci in these colonies, and after
solution of the gelatinous sheath the rods and cocci can
swarm. The rods form threads, and these may show a partial
or a total spiral formation like B. alba.

The retif orm zooglaea formation of B. persicina was formerly
described as Clathrocystis or Cohnia roseo-persicina, and by
Lankester as "peach-coloured bacterium."* The cells are
spherical or oval, of a reddish colour, and as much as 2'5 /*.
in diameter ; they form at first solid families bound together
by gelatinous material ; at a later period hollow bodies appear,
filled with watery fluid, and as much as 660 /*. in diameter ;
in these bodies the cells form a single peripheral layer. The
bladders are often torn or riddled with holes, and then they
have the form of a delicate network, which ultimately breaks
up into irregular bunches.

The red colouring matter which is present in the cells
differs from other colouring materials and is termed bacterio-
purpurine ; the same pigment is also contained in some of the
species of monas mentioned below, but it is quite different
from the colouring matter of micrococcus prodigiosus.
Bacterio-purpurine is of a peach- red colour, is insoluble in
water, alcohol, &c., and shows under the spectroscope great
absorption in the yellow and less in the green and blue, and
also cloudiness in the more highly refracting half of the
spectrum. No chlorophyll substratum is contained in the
colouring matter. In the cells, especially in old cells.
dark granules can be observed which consist of reguline
sulphur.

Beggiatoa mirabilis. — This organism occurs in sea-water,
forming whitish deposits on decomposing alga?, sea-weed, &c.
It is distinguished from tlie other beggiatoa by its large
transverse diameter — 30 p. The threads show segmentation,
at first into almost isodiametric pieces, and then into short

* Eabenhorst- Winter, Lit., p. 1. — Cohn, Beitrage, i., Part 3, p. 157. —
Lankester, Quart, Jovrn. of Micr. >c.. 1873, vol. 13, p. 408.

CLADOTHRIX DICHOTOMA.

491

cylindrical plates. Its mode of development is as yet other-
wise unknown.

Phragmidiothrix multiseptata.

Found by Engler in the salt water of the bay at Kiel. The
threads are 3 to 6 p. in thickness, and are subdivided by
transverse divisions into very short cylinders ; in these
cylinders longitudinal division then occurs in two or more
directions. From the minute coccus-like portions threads?
at first very thin but constantly becoming broader, are
formed.

Cladothrix dichotoma.

Very common in impure waters, in the waste waters ciadothm
from manufacturing places, &c. It may be artificially Occurrenc
cultivated in decoctions of decomposing algae, mud,

Fig. 137.— Cladothrix dichotoma. (After Cohn.)
Apparent dichotomous threads X 100. At a these are
more highly magnified (X 600), and the false dicho-
tomotis divisions are distinctly seen.

flesh, &c. It forms floating flakes and deposits on solid
substrata 1 to 2 mm. in height. The threads were
ormerly described as a species of leptothrix ; they form
pseudo-branches, some of tbe rods bending to one side
and elongating to form threads by continued sub-
division. This system of branches often attains great 1F1alse bran(

492 FISSION FUNGI WITH VARIABLE VEGETATIVE FORMS.

dimensions. The threads become segmented into long
rods, later into short rods, and finally into cocci ; but
this structure is at times only visible after the employ-
ment of means which kill the organism. The segments
of the threads as a rule pass out of the sheath ; at
times, however, the cocci grow to rods and threads in
the interior of the sheath. Under certain conditions
broken off portions of the branches are able to swarm,
and show cilia. At times the fungus forms branches
with regular spiral turns ; from these also portions may
be separated, and ultimately take on swarming move-
ments. According to Billet,* spores are formed in the
interior of the threads which compose the false branches.

Zopf reckons the Zooglsearamigerat to the cycle of develop-
ment of the cladotlirix ; this is a zooglsea branched like a
tree, containing in the first place cocci, later short rods, then
long rods, then leptothrix-likc threads, which at times become
spirally twisted, and by the branching of which the typical
cladothrix structure is ultimately formed.

According to Zopf also, the fungus described by Lankester
and Cohn,;j; under the name Myconostoc yreyarium, represents

portions of the threads of clado-
thrix. Myconostoc consists of
thin, colourless threads which are
grouped together in the form of
Efe. 138. -Myconostoc k"ot-like loose turns, and are sur-
gregarium (after Cohn) rounded by a transparent gelatin-
X 600. . ous sheath 10 to 17/*. in diameter.

J, gelatinous ball contain- Multiplication occurs, as in the

ing a roll of threads. ,.

Ji, individual threads. case ot aacoccus, by transverse

division of the gelatinous capsule.

A zooglaea is often formed by the adhesion of gelatinous
capsules. According to Zopf the spiral forms become broken
up at a later period into rods, and ultimately into coccus-like
fragments. As the result of the swelling of the jelly, the
enclosed rods become more and more separated from each
other, and ultimately escape from the jelly, and pass into u
swarming condition.

In the case of the following lower organisms, which may b'e

* Billet, Compt. rend., vol. 100, p. 1251.

f Itzigsohn, Kitzungsber. der naturf. Gen., Berlin, 1867. — Koch, Cohn*
Btitr.. ii., Part 3, p. 414.

I Cohn, Beitrfige, i., Part 3, p. 183.

CLADOTHRIX DICHOTOMA. 493

added here in the form of an appendix, their cycle of develop-
ment is quite unknown, and it is doubtful whether they
should be classed among the fission fungi.

Streptothrix Foersteriis the name given by Cohn to a thread- Streptoth
like fungus which he found in the concretions in the tear-
ducts of the human eye. This organism consists of fine
colourless threads, usually straight, but also sometimes
twisted, these threads showing at times, though seldom, dis-
tinct branching. The threads of leptothrix buccalis are
thicker, straighter, stiffer, and unbranched, and thus differ
from streptothrix. Nothing is as yet known as to the position
and the mode of development of this organism.

Spliserotilus natam. — Cells 4 to 9 /*. in length, 3 /*. in thick- Sphaerotil
ness, roundish or elongated ; they occur united in rows in
large numbers in the interior of colourless gelatinous sheaths,
forming long threads which appear as floating flakes, densely
felted like a tress of hair. Multiplication occurs by isolated
vegetative cells which develop new threads by continued sub-
division. They reproduce themselves by means of spores
which are formed endogenously in the vegetative cells. It
occurs in stagnant and flowing water ; the younger flakes are
colourless, the older yellowish-brown ; when spore formation
is taking place they are sometimes milk-white in colour, and
sometimes red.*

Spiromonas. — Cells flat like a leaf, twisted around an ideal Species of
long axis. Multiplication by transverse division.

Spiromonas volubilis. — Colourless, transparent ; rapid move-
ments and rapid turning around the long axis ; length, 15 to
18 jh

Spiromonas Oohnii. — Colourless cells very pointed at each
end, with a flagellum, and with 1^ turns. Breadth of the cells
1'2 to 4 /*. It occurs in very putrid water.f

In very foul watery fluids a number of minute organisms Red putrc

frequently develop in addition to the Clathrocystis roseo- tlve .

. . -. -,TI • • . . organisms

persicina described above, these organisms being also charac-
terised by their reddish colour, and possibly belonging to the
cycle of development of that fungus. They form red flakes
on all sorts of detritus at the bottom of the water, but they
swim at times on the surface ; even in the most marked
putrid condition of the water they do not die, but on the con-
trary apparently take part in the putrefactive process. They
are grouped together under the general name of the " peach-
red putrefactive organisms." No chlorophyll substratum
can be recognised in the colouring matter, and hence these
organisms are more properly classed with the fission fungi

* After Kabenhorst- Winter, Lit., p. 1.

f Beit r aye z. Biol d. Pflanzen, vol. i., Part 3.

494 FISSION FUNGI WITH VARIABLE VEGETATIVE FORMS

than with the lower monads, with which they have, however,
certain morphological resemblances. Common to them are
also the dark granules which are present in the pale red cell
substance, and which probably consists of sulphur (compare
Beggiatoa) ; and also their active movement caused by flagella.
Colin has distinguished the following varieties :* —

Monas vinosa. — Spherical or oval cells about 2'5 ju. in
diameter, often united in pairs. Cell substance pale red with
dark granules. Active swarming movement ; flagella not
observed.

Monas Okenii. — Short cylindrical cells, 5^. in breadth, 8 to
15/*. in length, rounded at the ends, slightly curved. Actively
mobile ; a flagellum at one end twice as long as the cell. Pale
red cell substance with dark granules.

Rhdbdomonas rosea. — Spindle-shaped cells 3*8 to 5 ju. in
breadth, 20 to 30 /i. in length; slow trembling movement; a
flagellum at one end. Very pale-coloured cell substance with
dark granules.

C D

Fig. 139.— Monads. (After Cohn.)

A, Monas vinosa. B, Monas Okenii.

6', Monas Warmingii. D, Rhabdomonas rosea.

Monas Warmingii. — Similar to Monas Okenii, but more
robust; 15 to 10 /u. in length, 8 /j.. in breadth; tumbling
movements ; a flagellum at one end. The pale red cell sub-
stance only contains dark red granules at each end ; the ends
are rounded.

* Beitrage z. Biol. d. Fftanzen, vol. i., Part 3.

495

PART III.
BIOLOGY OF THE MICRO-ORGANISMS.

Even at an early period, when elaborate experi-
mental investigations on the subject of the vital
peculiarities of the fungi were wanting, and when the
attempt was made mainly by philosophical speculations
to satisfy the already existing active interest in the signifi-
cance and mode of life of the fermentative organisms, a
definite and very important r6le in the economy of nature
was ascribed to the class of the fungi, and efforts were
made to bring the vital phenomena of the fungi, in so
far as they had been observed, into unison with this role.
These earlier views have latterly been confirmed in their
essential points by recent investigations and experiments ;
but in certain details marked differences have been
found.

The view as to the teleological function and signi- Former view*
ficance of the fungi rests chiefly on the absence of biological re-

chlorophyll; and this at once brings the fungi into
marked contrast with all other plants characterised by plants and
the presence of chlorophyll. While the latter, including
the algae, which are so closely allied to the fungi, obtain
the necessary carbon and nitrogen from the carbonic
acid, ammonia, and nitric acid which surround them,
and build up from these simple compounds with the aid
of the chlorophyll, the complex nitrogenous and carbona-
ceous materials which they contain ; and while these
plants are consequently able to assimilate their nutrient
materials from water, for example, which contains the
necessary mineral substances, and from the air, which
contains carbonic acid and ammonia; the fungi, on
account of their want of chlorophyll, cannot live in the
same manner, but require previously formed organic
substances in order to replace the waste products, and

496 BIOLOGY OF THE MICRO-ORGANISMS.

to build up new tissue. Hence they cannot exist in
pure water containing only mineral substances ; they
grow, on the contrary, only on dead organic matter, rich
in carbon and nitrogen, especially on dead plants and
animals; or they live as parasites, withdrawing from
their vegetable or animal hosts the organic substances
necessary for their life and growth.

Teleological From these facts we can at once understand the signi-
lower fungi, ficance of the fungi in the economy of nature. In order
to supply the necessary simple nutrient materials to the
chlorophyllous plants, it is essential that the sub-
stance of dead plants should be continually broken up
and reduced to these simple compounds.

The whole of the vegetation, which is yearly produced
and again dies, must be so altered in a relatively short
time that water, carbonic acid, and ammonia may be
again formed from albumen, carbo-hydrates, cellulose,
&c. ; and it is only under these circumstances that a
constant and increasing renewal of vegetation is con-
ceivable.

A portion of this destructive work is performed by
the animal organism ; the animal cells split up the
vegetable materials which have been taken in, and pre-
pares them for oxidation. The energy which had be-
come stored up in the complex chemical compounds of
the plant, from the conversion of the energy of the light
rays into a chemical energy by the aid of the chlorophyll,
is used up by the animal organism, and employed for
the production of heat, and for the various functions of
the body. This consumption of vegetable materials by
animals is, however, by no means sufficient to equalise
the production of vegetable substances and to keep the
amount of the simple nutrient materials of plants at such
a level as to suffice for the constant nutrition and growth
of new vegetation. It is evident that some other factor
must come into play in the economy of nature by which
a much more extensive destruction of dead vegetable
substances and a much greater formation of carbonic
acid and ammonia is brought about than by the vital
processes of animals ; and this necessity has become

BIOLOGY OF THE MICRO-ORGANISMS. 497

more apparent since we have learned that a scarcely
noticeable oxidation occurs when organic materials and
the oxygen of the air are simply in contact with each
other at the ordinary temperature, and that on the con-
trary it is the living cells which furnish the necessary
conditions for a rapid destruction and oxidation of
organic materials. Further, it must be pointed out that
the substance of the dead animal body must also be ex-
posed to destructive influences in the same manner as
dead vegetable materials ; for we also see in the case of
animal organic materials that the atmospheric oxygen
alone is relatively powerless to convert these compounds
into carbonic acid, ammonia, and water.

This dangerous gap in the constant process of re- The fungi
generation in nature is made good by the action of the 0rganicP (
lower fungi. They form the necessary factor which ^^^nder^
renders a rapid destruction and oxidation of dead organic them of use
materials, whether of animal or vegetable origin, possible, 0
and which reproduce the simple carbon and nitrogen
compounds which are necessary for the nutrition of
living and growing plants. The fungi are able to per-
form this role because they do not, like the chlorophyl-
lous plants, utilise the energy of the sun, nor obtain
their nutriment from carbonic acid and ammonia, but,
like animals, feed on the complex chemical compounds,
and utilise the energy so liberated for the performance
of their functions. They are the better able to do this
on account of the wide limits within which their ex-
ternal conditions of existence can vary without injury; also
on account of their extraordinarily rapid multiplication,
for which they use up a considerable amount of nutrient
materials in a short time ; and further, because under
such circumstances they only utilise a relatively small
proportion of the nutrient materials for their own growth,
while a much larger proportion is decomposed by their
peculiar fermentative actions, and thus prepared for
further oxidation. Lastly, it is as it were only a slight
alteration of their function when they at times settle as
parasites on living plants and animals, and lead to their
destruction by breaking up very rapidly the organic con-

32

498

BIOLOGY OF THE MICRO-ORGANISMS.

Pasteur's in-

asto^e008

nutritive

Fungi do not

require "oim-
plex organic

materials.

stituents of their host and converting them into simple
chemical compounds.

In correspondence with this view of the function and
the significance of the fungi, we must look for their
most important physiological peculiarities in the fact
that they ohtain their nutriment from complex organic
substances, and are unable to assimilate the carbon and
nitrogen from carbonic acid and ammonia. This charac-
teristic therefore formed the basis of former investi-
gations.

Pasteur was the first who made exact experimental
investigations as to the biology of the fungi ; these ex-
periments led to results which differed in many respects
from the views which had been held up till that time.
Pasteur showed more especially that yeast and mould
fungi were in so far able to live in a similar manner to
the higher plants in that they could assimilate the
nitrogen from ammoniacal salts, and even from nitrates,
and thus, like the chlorophyllous plants, could build up
the complex albuminous materials of their body from
simple substances. It was also found that different
fungi showed great differences in their conditions of life ;
that one required oxygen and led to rapid oxidation, that
another could live without oxygen, and then often
caused extensive though superficial decomposition of the
nutrient material ; that only certain fungi could tolerate
an acid reaction and great concentration of the nutrient
medium ; that different organisms grew most luxuriantly
at very different temperatures ; that one preferred this,
and the other that kind of nutrient material, and that
they were not all equally capable of utilising the nitrogen
of ammonia, or of nitric acid ; that, lastly, even one and
the same organism behaved very differently as regards
their tissue change and energy under varying external
conditions.

It is true that the former views as to the significance of
^e ^unS^ ^u na^ure were not completely upset by these
results of experimental investigation. For it was still
certain that all the lower fungi were able to live on com-
plex chemical materials — that, in fact, these materials

BIOLOGY OF THE MICRO-ORGANISMS. 499

were preferred as nutrient substances, and that therefore
the destruction of dead organic substances was chiefly
caused by fungi ; further, that carbonic acid could not in
any way be utilised either for assimilation or for growth.
But the physiological characters by means of which they
were able to play their peculiar role no longer appeared
to be so simple, and could no longer be defined in a few
words, but were made up of a number of processes
which required separate consideration, and which varied
markedly according to the species of the fungus and the
external conditions which surrounded it. Hence we
can no longer content ourselves with a general formula
if we would obtain an insight into the vital manifesta-
tions of the fungi; but we must proceed by the inductive
method, and seek to understand the life of the lower
organisms from a large number of individual observations
and experiments. In this place we must therefore enter
into a minute and detailed discussion as to the biology
of the fungi, and we must do this the more thoroughly
because this side of mycological investigation is of very
great importance for hygiene.

The various biological phenomena which we observe
in the fungi can be subjected to experimental study in
the same manner as the vital phenomena of more com-
plex living beings, e.g., of animals or of the higher
plants. If we take the latter as our basis, we must
proceed from the more complex to the simpler, but it is
probable that many biological problems which have
proved insoluble in the case of the more complex organ-
isms, in spite of very numerous investigations, will be
much more readily solved in these simple beings, and that
thus at a later period the biology of the fungi will throw
light on the biology of higher plants, more especially
when we employ the methods of investigation which
have been found good in the case of the former.

If we wish to study the tissue change of any of the
more complex organisms we generally attempt in the
first place, by a number of variations in our experiments

500 BIOLOGY OF THE MICRO-ORGANISMS.

on nutrition and tissue change, to determine the kind
and quantity of material which is taken up by them,
and to ascertain the normal relation of the other external
conditions which are necessary for the regular progress
of life; further, we investigate the fate of the materials
taken up, and how they are used in the body, also the
excretory products, and finally the functions of the
organs; and we are thus in a position to form an
approximate idea as to the alterations of the tissue and
of the energy which form the basis of the life of that
organism.

We must study the biology of the lower fungi in a
similar manner. In the case of these also we must in the
first place ascertain experimentally the necessary condi-
tions of life ; we must learn what solid nutrient materials
must be supplied to the fungi, what role is played by
oxygen, and whether temperature, atmospheric pressure,
light, &c., exercise any noticeable influence on the growth
and the multiplication of the fungi. Where multiplica-
tion occurs by means of spores, we must ascertain what
are the conditions necessary for this act, and also on
what external circumstances the germination of these
spores depends.

In the second place, it is necessary to study the results
of the life of the lower fungi. Among these we learn, in
the first place, the assimilation of the nutrient materials,
the tissue change in the cells, and at the same time the
various manifestations of energy — for example, growth,
multiplication, and fructification; further, we find that
the fungi excrete various products of tissue change which
are of special interest ; and finally, that they exert under
certain circumstances two peculiar actions which require
more minute study, viz., fermentative action and the
production of disease.

The study of the conditions of life also implies a dis-
cussion of the influences which are hurtful and destructive
to life. It is, however, advisable to consider the pheno-
mena of involution and of the death of the lower fungi
in a separate chapter, as well as the description of those
means by which we can interfere with the growth or life

CONDITIONS OF LIFE OF THE LOWER FUNGI. 501

of the fungi. These means are identical with the disin-
fecting agents which have recently hecome of so much
importance.

Finally, the investigations as to the biology of the
lower fungi must not be limited to the individual; the
behaviour of a continued series of individuals must be
taken into consideration. More especially we must direct
our attention to the occurrence of modifications — to the
formation of varieties, races, and species.

The discussions in the following pages are limited
to those fungi, which are of importance from a hygienic
point of view (mould fungi, yeast fungi, and fission
fungi); with regard to the other fungi and micro-
organisms which were mentioned in studying the mor-
phological characters, we must refer to de Bary's
excellent description of the morphology and biology of
the fungi.

I. CONDITIONS OF LIFE OF THE LOWER FUNGI.

In order to understand the nutritive processes, it is in Conditions of
the first place necessary to take a short survey of the
chemical composition of the fungi. We must then ascer-
tain the importance of the individual nutrient materials,
in the first place of the nitrogen, and then of the carbon,
hydrogen, and combined oxygen, of the mineral sub-
stances, of the water, and, finally, of the free oxygen.
Special attention must also be paid to the concentration
and reaction of the nutrient mixture. Of less import-
ance is the influence of atmospheric pressure, light,
electricity, and mechanical movement; while the action
of various temperatures, the fermentative action, and the
concurrent growth with other fungi are of very great
importance in the development and growth of the indivi-
dual micro-organisms.

In almost all these points the mould fungi, yeast
fungi, and fission fungi show such differences that each
must be separately studied.

502 BIOLOGY OF THE MICRO-ORGANISMS.

(a) Conditions of Life of the Mould Fungi.

(a) Mould 1. Chemical Composition of the Mould Fungi. — Until

chemical recently we had no complete analysis of the mould
constitution. fungj . nevertheless it was assumed that their composi-
tion was similar to that of the higher fungi. In the
case of the latter, the following numbers represent the
average result of various analyses : —

88 per cent, water, 3 per cent, nitrogenous and 5
per cent, non-nitrogenous organic materials, 1 per cent,
ashes; when dried in the air — 17 per cent, water, 25 per
cent, nitrogenous and 45 per cent, non-nitrogenous
substances, 8 per cent, ashes.

Sieber* has recently made some analyses of the mould
fungi, but, as it appears, without sufficient precautions
as to the purity of the materials used. The following
was the result — (1) of a cultivation of penicillium and
mucor in a nutrient solution of gelatine and sugar : —

Soluble in Ether 187 per cent, of the dry substance.

Alcohol... 6-9

Ashes 4-9

Albumen 29'9

Cellulose 39'6

(2) Of a cultivation in a saccharine ammoniacal solu-
tion, consisting mainly of Aspergillus glaucus : —

Soluble in Ether 11*2 per cent.

„ Alcohol 3'4 „

Ashes 07

Albumen 28'9

Cellulose 557

As compared with the analysis of the yeast and fission
fungi (as given below), the marked excess of non-nitro-
genous substances is specially noticeable; this in the
main depends on the fact that in the case of the mould
fungi a large amount of cellulose is present, and that it
is only in the contents of the cells that albuminous sub-
stances exist ; and also on the fact that soluble saccharine
matters are present in recognisable quantity.

* Journ.f. prakt. Chemie (2), 23. 412.

CONDITIONS OF LIFE OF THE MOULD FUNGI. 503

The mineral constituents in the case of the higher
fungi have the following average composition : —

50 per cent, potash, 1*5 per cent, soda, 1 per cent,
lime, 2 per cent, magnesia, 1 per cent, oxide of iron,
30 per cent, phosphoric acid, small quantities of silicic
acid and hydrochloric acid, and very varying quantities
of sulphuric acid.

According to this analysis, potash and phosphoric acid
seem to be of most importance.

Stutzer* has found that mould fungi washed in water,
and dried over sulphuric acid, showed a total of 3'776
per cent, of nitrogenous materials, consisting of 3 '026
per cent, of proteids, and 1'539 per cent, of nuclein.

2. The Nutrient Materials of the Mould Fungi. — Cor- Nutrient
responding to the chemical composition, a large amount m
of water is necessary for building up and maintaining
the constituents of the mould fungi; also organic sub-
stances containing carbon and nitrogen, and of the
mineral constituents, chiefly potash and phosphoric acid.
The chemical compounds which these nutrient materials
furnish, and the relative amount in which the latter must
be present, can however only be ascertained by special
experiments.

A series of experiments in this direction were formerly jjaulin's
made by Pasteur, and have been carried out in a very thorough experiments,
manner by Baulin,f who proceeded as follows : — He cultivated
Aspergillus niger in a nutrient solution which, as the result
of numerous experiments, he had reason to believe was par-
ticularly suitable for the nourishment of the fungus, and which
may be regarded as the normal solution. It was composed of —

1500 grms. of water.
70 „ „ Candy-sugar.
4 „ „ Tartaric Acid.
4 ,, ,, Nitrate of Ammonia.
0*6 ,, „ Phosphate of Ammonia.
0'6 „ „ Carbonate of Potash.
0'4 „ „ Carbonate of Magnesia.
O25 „ „ Sulphate of Ammonia.
0-07 „ each of Sulphate of Iron, Zinc Sul-
phate, and Silicate of Potash.

* Zeitschr.f.physiol. Chem., vol. vi., 573.
t Eaulin, Compt. rend , T. 50, p. 229.

504

BIOLOGY OF THE MICRO-ORGANISMS.

Nageli 's
experiments.

Substances
Huitable for
supplying the
necessary
nitrogen.

If Raulin sowed spores of Aspergillus niger in this fluid,
which was kept at a temperature of about 35° C. in shallow
covered vessels in a layer 2 to 3 ctm. in depth, a fructifying
mycelium was formed after three days ; this was removed, and
from the remaining fluid a new crop was obtained after three
days more. After the removal of this second crop the nutrient
materials of the fluid seemed to be almost entirely exhausted.
The weight of the total growth when dry was determined, and
was found to amount to about 25 grms. This result was
compared with that obtained when one or other of the con-
stituents of the normal nutrient solution was omitted.
Raulin found that the absence of phosphoric acid had the
greatest influence, the resulting growth being reduced to ^w
part of the normal ; that the absence of ammonia diminished
the growth to ^ ; and of potash to ^. No constituent of
Haulm's fluid could be omitted without harm; even the
omission of the zinc had a marked influence on the result.

More complete experiments of a similar character
have recently been made by Nageli. He showed that
there were certain sources of error in the former experi-
ments ; that, for example, sufficient care had not been
taken to secure pure cultivations and to exclude all other
organisms ; that, further, the access of air, the reaction,
the most favourable concentration of each of the nutrient
materials (the so-called "optimum of concentration"),
and, finally, the alteration of the nutrient solution by the
growth of the fungus itself, were not sufficiently taken into
account. Nageli's* numerous and exact experiments
led to the following results : —

The necessary nitrogen cannot be obtained from free
nitrogen, nor from the nitrogen which is in combina-
tion with carbon in cyanogen ; in like manner nitrogen
in combination with oxygen seems to be unsuitable, at
any rate nitre-compounds, such as picric acid and nitro-
benzoic acid, were very bad nutrient materials. On the
other hand, the best forms seemed to be the NIL
groups; the NH group was less suitable. In corre-
spondence with this, the best materials for the nourish-
ment of the fungi were : ammoniacal salts (sal ammoniac,
phosphate of ammonia, nitrate of ammonia ; acetate,
oxalate, succinate, and tartrate of ammonia, &c.) ; also

* Nageli, Vntersuchungen iiber niedere Pilze, Munich, 1882.

CONDITIONS OF LIFE OF THE MOULD FUNGI. 505

hydrochlorate of methylamine and aethylamine, tri-
methylamine ; leucine, asparagine; acetamide, oxamide ;
and urea. The best nitrogenous nutrient materials
were the soluble albuminates and peptone. Nitrogen
can also be assimilated by the mould fungi from
nitrates; probably in this case there is a gradual
reduction of the nitric acid to nitrous acid, and ulti-
mately to ammonia ; but these reduction products have
not yet been demonstrated. In comparative experi-
ments no marked difference was found between the
nutrient value of the nitrates and the salts of ammonia ;
urea was better than either, and peptone was better
than urea.

The necessary carbon can be obtained from the For the supply
groups CH3 or CH2, and in that case it is of advantage, of carbon'
and under certain circumstances necessary, that several
carbon atoms should be united in one molecule. No
carbon can be assimilated if in any given chemical com-
bination there is only a union of carbon with nitrogen,
oxygen, or carbon. Hence the following substances are
not suitable for yielding carbon : carbonic acid, cyanogen,
formic acid, urea, oxalic acid, and oxamide. Of course,
also, those combinations which are not soluble in water
are unsuitable as food, such as the higher fatty acids
and the insoluble humine substances. Apart from the
number of the carbon atoms, the ease with which the
compounds can be decomposed seems to be of import-
ance ; the more readily the compound can be broken up
by other agents, such as by oxidising substances, the
more easily can it be assimilated. Nageli has formed
the following empirical table of the nutrient value of
various organic compounds with regard to carbon : 1.
Various kinds of sugar. 2. Mannite, glycerine ; the
carbon group in leucine. 3. Tartaric acid ; citric acid ;
succinic acid ; the carbon group in asparagine. 4. Acetic
acid ; sethylic alcohol ; quinic acid. 5. Benzoic acid ;
salicylic acid ; the carbon group in propylamine. 6.
The carbon group in methylamine ; phenol. Pyrogallic
acid and tannic acid were also fairly good sources of
carbon ; and finally we may mention the observa-

506

BIOLOGY OF THE MICRO-ORGANISMS.

tion made by Pasteur in 1858, that racemic acid,
which is a combination of two forms of tartaric acid,
the one rotating to the right, and the other to the left,
was able to nourish the mould fungi, in the form of
racimate of ammonia, but that it was only the form
which rotated to the right which is taken up by the
fungi, while the other is left in the nutrient fluid.

It is very difficult to compare the nutrient value of
the various sources of carbon, because they evidently
vary in their action in accordance with variations in the
sources of nitrogen ; and again, if we take care that the
nitrogenous materials are the same it becomes a ques-
tion whether they may not be assimilated in another
way when the carbon sources are different. Hence we
would apparently obtain a more exact mode of comparison
if we combined the sources of carbon and nitrogen, and
then subjected some of these combinations to compara-
tive experiments. In this way Nageli has constructed
the following scale, proceeding from the best to the
worst nutritive materials: 1. Albumen (peptone) and
sugar. 2. Leucine and sugar. 3. Tartrate of am-
monia, or sal ammoniac and sugar. 4. Albumen (pep-
tone). 5. Leucine. 6. Tartrate of ammonia; succinate
of ammonia ; asparagine. 7. Acetate of ammonia.

Thus albuminous materials, and those belonging to
the group of carbo-hydrates, seem to be the normal nutri-
tive sources of the mould fungi, and it is chiefly these
materials on which they feed under normal circum-
stances. But, on the other hand, it is noteworthy how
widely the nutrient materials may vary, the fungi sub-
sisting with ease on very different chemical substances,
and also how the mould fungi seem to be able to main-
tain their existence as the result of their ability to
obtain nutriment from the most different sorts of
chemical substances.

The supply of hydrogen and of combined oxygen is
partly provided for by the above-mentioned carbon and
nitrogen compounds, and partly by water and free
oxygen. — Sulphur also takes part in the composition of
the organic constituents of the mould fungi, and is

CONDITIONS OF LIFE OF THE MOULD FUNGI. 507

probably contained in all true albuminous materials.
According to Nageli's experiments, it can be taken from
the albuminates, and as well, or better, from sulphates,
sulphites, or hyposulphites ; sulpho-acids may also act
as substitutes, but not sulpho-urea compounds or the
sulpho-cyanides. Exact experiments, however, as to
the supply of sulphur are very difficult to carry out,
because the small quantities necessary for suitable
nourishment commonly adhere as impurities to the
other nutrient materials, as for example, to the sugar.

Water and mineral substances are of great importance Supply of
for the nourishment of the mould fungi. A large ^
quantity of water is necessary for the nutriment of the
mould fungi; in part it enters into the complex sub-
stances which are built up by the fungi, in part it forms
the chief constituent of the newly formed tissue of the
fungus, and in part it acts as a dissolving and trans-
porting medium, and thus enables the materials to
move in the cell, just as in the case of the higher
organisms. It is of special interest, as regards the
necessity for water, to ascertain the smallest quantity
necessary for the mould fungi to obtain sufficient
nourishment. As regards this question we shall enter
into further details when considering the subject of
nutrient materials with reference to their concentra-
tion.— According to Nageli's more recent researches, Need of
a relatively small quantity of mineral substances are
necessary. While the chlorophyllous plants require,
besides phosphoric acid, sulphuric acid, and alkalies,
also calcium and magnesium, and in addition iron,
silicic acid, and chlorine, the mould fungi are satisfied
with sulphuric acid, phosphoric acid, potash, and calcium
or magnesia. The potash, however, cannot be replaced
by sodium, although it may by caesium and rubidium.
In the place of calcium we may have, besides magnesium,
also barium or strontium. One element from the group
of the alkalies, and one from the alkaline earths, must,
however, always be present ; each of these representa-
tives of the two groups appear to have different functions,
which are probably the following : the earthy com-

508

BIOLOGY OF THE MICRO-ORGANISMS.

pounds in part in the form of earthy phosphates, only
form deposits in plasma and in the cell membrane, while
the alkaline salts are chiefly present in solution in the
free fluid of the cell in the form of primary and secondary
phosphates of potash (KH2 P04 and K2 H P 04, the first
having an acid, and the second an alkaline reaction).

Free oxygen. jn addition to the solid and fluid nutrient materials
which have been already mentioned, the mould fungi
require for their normal development and growth the
presence of free, gaseous oxygen. Pasteur found
that like the higher plants, the mould fungi (penicil-
lium) take oxygen from the surrounding atmosphere.
The need of the mould fungi for oxygen is also
shown by the places in which they occur; they are
limited to those situations which are in immediate
contact with free oxygen. Hence they grow only on
the surface of fluids (in like manner on the external
surface of animal or human bodies, in the air-passages,
&c.), and then only in so far as they can obtain the
oxygen dissolved in the fluids. The quantity of oxygen
necessary is, however, small; and, according to Brefeld,
the mould fungi which do not cause fermentation will
grow when placed in an atmosphere of carbonic acid,
unless it contains less than -5 J^ of its volume of air.

If the mould fungi are immersed in fluids free from
oxjgen their normal growth ceases; and some fungi
(such as mucor) can only form yeast-like buds, and
in this way, according to Brefeld, provide for the main-
tenance of the species. Under these circumstances, how-
ever, the yeast-like cells set up fermentation, with
plentiful development of carbonic acid and the stream of
bubbles of carbonic acid again brings the elements of
the fungi to the surface where they are able to grow and

Growth in the fructify in a normal manner. — The growth of the mould
y' fungi in the animal body apparently forms an exception to
the above rules. It has been recently proved, as a result
of numerous experiments, that the spores of aspergillus and
mucor can sprout in the kidneys and in the internal organs
of the living body, and grow to form a mycelium. As yet
however, only a limited formation of mycelium has been

Behaviour
'

CONDITIONS OF LIFE OF THE MOULD FUNGI. 509

obtained under these circumstances, and the production
of fruit-hearing mycelium and spores has never heen
observed ; hence the relation of the fungi to oxygen may
be stated by saying that normal growth with fructifi-
cation can only occur in an atmosphere containing free
oxygen, while on the other hand, only a formation of
mycelium occurs where (as in many animal bodies)
there is no free oxygen at their disposal. This view
corresponds also on the whole with the facts as to the
occurrence of the parasitic mould fungi in the lower
animals ; the pathogenic species of empusa, cordyceps,
botrytis, and isaria form in the bodies of the caterpillars
and insects which they attack well-developed mycelium,
and ultimately the so-called cylindrical gonidia ; true
fructification, however, only takes place by means of
fruit-bearing hyphae, which have burst through the
surface and come in contact with the air.

Thus far we have discussed the question of the quality Quantity of
of the nutrient materials which are required by the mould material.
fungi. In addition to the quality we must now allude
to their quantity. It is evident that either too small or
too large a quantity of any of the nutrient materials
will have an unfavourable effect, and that there must be
an optimum of quantity as regards each individual com-
ponent at which nutrition goes on best ; this optimum,
however, will depend on the general composition of the
nutrient mixture, and will vary according to the amount
of the other substances which are present at the same
time. On this subject very little is as yet known, and
on]y as regards two points are the experiments suffi-
ciently numerous and precise to admit of their discussion
at the present time — namely, in the first place, the
amount of water which is necessary for a suitable nutri-
tive mixture, or, in other words, the concentration of the
mixture ; and, in the second place, the quantity of free
alkali or free acid, i.e., the reaction of the nutrient mixture.

As regards the concentration or the amount of water Limits within
in the nutriment, it may vary very considerably without

completely preventing the growth of the mould fungi; the water may
mould fungi are in this respect much less sensitive than

510 BIOLOGY OF THE MICRO-ORGANISMS.

the yeast or the fission fungi. Some mould fungi can
grow in extremely dilute nutrient mixtures which only
contain traces of the necessary nutrient materials. (This
has been especially observed with regard to penicillium.)
While, however, in this respect the vital activity of the
yeast and fission fungi is almost the same, the mould
fungi, on the other hand, have the advantage when we
come to deal with a small amount of water and marked
concentration of the material. Under such circumstances
they are by no means sensitive ; nutrient mixtures from
which a great part of the water has been removed by
evaporation, or by the addition of salt or sugar, and
which have therefore become unsuitable for the nutrition
both of the budding and fission fungi, will still be avail-
able for the growth of various mould fungi. We have
not yet gained exact information regarding the upper
and lower limits of the amount of water, and such in-
formation is very difficult to obtain, because the quantity
varies according to the other constituents of the nutrient
medium, and according to the varying species of the
mould fungi. In preserving articles of food, we have
learnt by experience that salted or smoked meat,
for example, which contains 50 per cent, of water,
is no longer a suitable soil for fission fungi, but
it may, nevertheless, become mouldy; in order to
prevent the formation of mould, the amount of water
must be reduced to only 10 to 12 per cent. ; if,
however, sugar is present at the same time in large
quantities, mould formation is prevented, even with
as much as 80 per cent, of water. — These numbers
indicate the lowest limit as regards the amount of
water ; the optimum is much higher, perhaps 80 per
cent., so far as the dependence of the optimum on the
quantity of the other nutrient materials permits us to
give definite numbers. — All the mould fungi, however,
are not in like manner indifferent with regard to great
concentration of the material on which they grow.
Certain fungi appear to be much more sensitive, espe-
cially some which lead a parasitic life, and which only
occur in moist seasons and in moist localities.

CONDITIONS OF LIFE OF THE MOULD FUNGI. 511

The reaction of the nutrient mixture has a most im- Influence of
portant influence on the growth of the mould fungi, of the nutrient
They seem to be most sensitive to an excess of alkali, material,
although some forms occur on substrata which have a
marked alkaline reaction ; an excess of acid is not nearly
so hurtful. Free tartaric acid may be present in the
nutrient mixture up to 5 per cent., and free phosphoric
acid up to 1 per cent., or more, without preventing the
development of mould fungi. This point is of great
importance, because in this respect, also, there is a
difference between the mould fungi and the majority of
the fission fungi, which are very sensitive to excess of
acid, and because by the reaction of the nutrient
material alone the kinds of fungi which obtain the
mastery when growing together can be influenced. — But
on this point also we can give no definite figures which
take into account the differences in the nutrient solution,
and the specific properties of the various forms of fungi.

As has been mentioned, there must be a most favour-
able proportion for all the other nutrient materials, and
increase or diminution of the quantity will exercise an
unfavourable action. Further, any admixture of foreign
materials which are not nutritious must render the
nutrient mixture to a certain extent unsuitable, even
when such materials are not poisonous for the fungi, and
do not hinder their growth even when present in great
concentration. Finally, poisonous materials which have
a specific noxious action on the growth of the mould
fungi may be present in the nutrient substratum or in
the surrounding air. The action of these substances
will be discussed in the chapter on "Disinfection."

At times the mould fungi can convert insoluble mate- Fermentative
rials into soluble, substances which can be absorbed,
and this is done by the formation of suitable ferments.
For instance, in the case of penicillium and aspergillus
niger, the production of a ferment which inverts cane-sugar
and maltose* has been demonstrated, and Van Tieghem
showed that penicillium and aspergillus niger were
able to split up tannin into gallic acid and glucose; the

* Bourquelot, Compt. rend., vol. 97, p. 1322.

512 BIOLOGY OF THE MICRO-ORGANISMS.

solution of cellulose, also, has been frequently noticed as
a result of the penetration of mould fungi into the tissues
of plants, and is only explicable by the agency of
ferments.

The parasitic existence of the mould fungi, in which
they take the necessary nutrient materials from the host
on which they grow, will be considered at greater length
further on.

8' Other Conditions of Life of the Mould Fungi.-

f actors. Increased and diminished atmospheric pressure, light

and electricity, have not yet been exhaustively studied as
regards their influence on the growth of the mould fungi ;
in so far as existing observations enable us to draw con-
clusions on this subject, they appear to have no marked
effect. Nothing is known as regards either a disturbing
or favourable influence of movement of the nutrient mix-
ture; and with regard to a favourable or inhibitory
action of fermentation on the growth of the mould fungi
there can be no question whatever, for with the above-
mentioned exceptions they do not cause fermentation.
There remain, however, some conditions of life which
may influence the growth of the fungi, more espe-
cially temperature, and concurrent growth with other
fungi.

Temperature. Temperature only requires consideration in so far as
it varies within medium limits. The extremes of cold
or heat will be considered among those conditions
which may cause the death of the fungi. In the case
of those temperatures which come into play under
normal conditions, the same points are of importance
as were mentioned with regard to the concentration
of the nutrient materials. In the case of the mould
fungi there exists an optimum of temperature at which
they grow most quickly and flourish best; but this
optimum differs according to the species of fungus, and
also according to the other conditions of life and nutri-
ment, in any given case. The optimum for penicillium
is quite different from that for aspergillus, and they both
differ from that of mucor. Penicillium glaucum appears
to grow best at a temperature of about 20° C.; it grows

CONDITIONS OF LIFE OF THE MOULD FUNGI. 513

also, however, at relatively low temperatures (at + 2'5°
C.), which are but little above the freezing point; as
the temperature rises, so does the energy of their growth
increase, till the optimum is reached; it then again
diminishes and ceases entirely at about 43° C.

In the case of Aspergillus glaucus the optimum of
temperature lies between 10° and 12° C.; of Aspergillus
flavus about 28° C. ; of Aspergillus niger from 34° to
35° C. ; of Aspergillus fumigatus between 37° and 40°
C. (Siebenmann) ; of Oidium lactis between 19° and
30° C., &c. — From these figures we may draw the
important conclusion, as regards the spread and the arti-
ficial cultivation of the mould fungi, that the temperature
must often determine what species develops and obtains
the mastery in any given nutrient material.

The simultaneous occurrence of other kinds of fungi Concurrence
in the same solution exerts a very important influence ™
on the growth of a cultivation of mould fungi. While it
is easy to obtain a luxuriant growth of the mould fungi
in solutions in which they alone have been sown, and
which are protected against the entrance of other organ-
isms, there may be no growth of mould fungi in such a
solution if bacteria have entered at the same time,
and if the nutrient solution in question permits the latter
organisms to multiply most rapidly. Under these cir-
cumstances, those conditions of life which differ in the
case of the mould fungi, the budding fungi, and the
fission fungi are of special importance; of these con-
ditions the chief are the concentration and reaction of the
nutrient material. In a mixture which contains only a
small quantity of water, and which has a marked acid
reaction, but few kinds of fission fungi can develop ;
where, therefore, these conditions are present, the soil
belongs exclusively to the mould fungi and the yeast
fungi. Thus, the mould fungi can obtain the mastery
in a soil where, if it were less acid and contained
more water, the fission fungi would certainly gain
the upper hand, because they could assimilate the
nutrient materials more energetically and take them
away from the mould fungi. This concurrence between

33

514 BIOLOGY OF THE MICRO-ORGANISMS.

different classes of fungi is important, and must be
noted under various other circumstances. A similar
concurrence naturally occurs also among the species
of one and the same class ; in that case, however,
other factors come into play, and lead to one or
other species gaining the upper hand. Temperature
has a very marked influence ; if, for example, we
employ a nutrient medium at 15° C., in which the spores
of Aspergillus fumigatus and of penicillium have been
sown, only the latter fungi will develop well, and they
will grow to such an extent that growth of the aspergilli
cannot occur, although this would have taken place
had there been no penicillium spores in the material in
the first instance; and conversely, where both species
are sown together in a medium kept at 35° C. only the
aspergilli ultimately develop. Other nutrient conditions
also act in a similar manner, and hence the resulting
cultivation and also the presence of any given mould
fungus in nature does not rest alone on the various con-
ditions of life which are present, but also depends in a
very important manner on the other species of fungi
which may have reached the nutrient soil at the same
time and may be growing in concurrence with it.
Conditions of 4. Conditions of Spore Formation and Spore Germina-
*pore forma- ^0?l< — jn the case of the mould fungi, the formation of
spores is such an essential part of the life of the fungus
that we cannot regard the formation of mycelium with-
out fructification as a normal and complete development.
The conditions of life described above hold good not
only for the growth of the mycelium, but also for fructi-
fication and the formation of spores; it has already been
pointed out how necessary the presence of ox3*gen is for
the latter process, and in this place we need only mention
the few facts that are known with special reference to
Conditions of the act of the germination of spores. For this process
turn6 forma" we do not as a rule absolutely require the presence of
any particular nutrient material, with the exception of a
large quantity of water. The formation of the germi-
nating tube takes place at the expense of the nutrient
materials which have been stored up in the spore, and it

CONDITIONS OF LIFE OF THE MOULD FUNGI. 515

is not till development has reached a certain stage that
the above-mentioned nutrient materials hecome necessary.
Hence the sprouting of moistened spores can be observed
even on glass plates. In the case of some fungi how-
ever, for example Mucor mucedo, it is true that the first
sprouting can only occur on suitable soil. — Besides
water the presence of oxygen and a suitable tempera-
ture are also necessary for the process of germination.
Here also the minimum, optimum, and maximum of
the temperature differ in the case of different species of
fungi. In the case of penicillium spores the former is
about +0'5° C., the latter about +43° C., and the
optimum about +22° C.; in the case of Aspergillus
fumigatus, on the other hand, the minimum, according
to Lichtheim, is 15° C.— The presence of light is not
necessary for the germination of the spores of the fungi.
Between the point when the conditions necessary for
germination come into play and the formation of a germi-
nating tube a certain period of time is necessary, the length
of which is dependent on the species of spore, and pro-
bably, above all, on the thickness of the spore membrane,
and varies from a few hours to several days. Similar
variations also exist with regard to the duration of the
vitality of the spores. In the case of the uredo and Duration of

.-,. P., /.. .11 .1 the vitality of

aecidium spores or the rust iiingi, as well as in the the spores.
case of peronosporeae, the duration of vitality is only
a few weeks, while the spores of Penicillium glaucum
are able to sprout after a year and a half, those of
Aspergillus niger after more than a year, those of
Mucor stolonifer after a year, of Aspergillus flavus
after six 3*ears, of Aspergillus fumigatus after ten years,
and of Tilletia caries and Ustilago carbo after about
eight years.* There is a further peculiarity in con-
nection with the spores, namely, that they are only
able to sprout after a considerable period of rest.

* Quoted from de Bary.

516 BIOLOGY OF THE MICRO-ORGANISMS.

b. Conditions of Life of the Budding Fungi.
1. Chemical Composition of the Budding Fungi.

- ^S re&ards the budding fungi, very numerous experi-
cai compost- ments have been made, which enable us to obtain a
fairly accurate idea of their chemical composition and of
their tissue change. These experiments have almost
entirely been limited to the ordinary yeast of beer,
which on account of its value in the preparation of food
has always excited special interest. It is seldom that
other species of these fungi, such as Mycoderma vini
(A. Schultze, in Mayer's Chemistry of Fermentation],
have been chosen for investigation.

Complete analyses of yeast have been published by
the following authors : Schlossberger, Mulder and
Wagner, Mitscherlich, Pay en, Liebig.* The following
was the average result in washed and dried yeast,
freed as much as possible from ashes : —

48 per cent. C, 9 — 12 per cent. N, 6 — 7 per cent.
H, 0*6 per cent. S.

More recent analyses by Niigelif have led to the
following results in the case of yeast used for low
fermentation : —

Cellulose and mucous material of cell wall 37 per cent.

Albuminous materials 45 „

Peptone 2 ,

Fat 5

Extractives (glycerine, leucine, &c.) ... 4 ,

Ashes ... ... ... ... ... ... 7 „

. Yeast which has been carrying on fermentation for a
considerable time contains, according to Pasteur and
others, a markedly less amount of nitrogen (only 5*0 to
5*5 per cent.) . — Schlossberger and Mulder have attempted
to isolate the albuminoid materials, either by treatment
with potash lye or with acetic acid ; and they made out
that the isolated materials had a composition closely

* See Mayer, Lehrbuch der Giihrungschemie, 1879, p. 110. — S«hiitzen-
berger, Gdkrungserscheimmgen, p. 58.

f Sitzunysber. d. bayr, Acad. d. Wiss. 1878, May.

CONDITIONS OF LIFE OF THE BUDDING FUNGI. 517

allied to that of the proteids. More recently an albu-
minoid material has been obtained from the yeast cells
by boiling with dilute hydrochloric acid and precipi-
tating with rock salt; this material is termed myco-
protein, and plays an important role in the composition
of the fission fungi. The amount of myco-protein has
not as yet, however, been ascertained in the case of
yeast (Nencki*). If the material remaining after the
action df potash lye is treated with acetic acid and
water, a substance is obtained, which, on analysis, gives
44*9 per cent. C, 6*7 per cent. H, 0*5 per cent. N
(according to later analyses by Nageli and Low 41*4
per cent. C, and 6*6 per cent. Hf), and thus it seems to
be fairly pure cellulose. These substances can be
transformed, by boiling with sulphuric acid, into
fermentescible sugar, and do not dissolve in ammoniacal
oxide of copper, being therefore somewhat different
from ordinary cellulose. — StutzerJ found in yeast
which had been extracted with alcohol and then dried
by means of sulphuric acid, 8*648 per cent, of total
nitrogen, 5*519 per cent, of proteid nitrogen and 2*257
per cent, of nuclein nitrogen.

The amount of water in fresh yeast which is able
to grow is 40 to 80 per cent. If there is a greater
or less quantity of water the yeast is no longer intact
or capable of multiplication.

The mode in which the relation between non-nitro- Eolation be
genous cellulose-like constituents and the proteid sub-
stances undergoes alteration, as compared with the
mould fungi, is worthy of note ; in yeast we find
37 per cent, of cellulose, and 47 per cent, of albuminous
materials ; in the mould fungi there is about 50 per
cent, of cellulose, and 29 per cent, of albuminous
materials. — However, it is not quite correct to reckon
the quantity of nitrogen found as belonging entirely to
albumen ; part of it belongs to other substances, such
as leucine and tyrosine, which can be obtained in

* Nencki, Beitrage zur Biologie der Spalfpilze, 1880, S. 48.

f Journ.furprakt. Cftem., No. 5, vol. 17.

£ Stutzer, Zeitschr.f.physiol Chemie, vol. vi., p. 572.

518

BIOLOGY OF THE MICRO-ORGANISMS.

Yeast ashes.

certain quantities from yeast by extraction with ice-
water (with regard to this point see below). In like
manner, besides cellulose, we find gum-like bodies,
glycerine, succinic acid, &c., which are also carbonaceous
and non-nitrogenous materials ; usually, however, these
substances occur in too small quantities to exert any
marked influence on the relation between proteid and
cellulose.

Of the several analyses of the ashes of yeast, the
following results seem the most trustworthy (Mit-
scherlich) : —

Potash

Phosphoric acid

Calcium

Magnesia
Silicic acid

Ashes of Yeast.
High Fermentation.
38'8 per cent. .
53-9

i-o „

6-0
Traces

Ashes of Yeast.
Low Fermentation.
. . . 28'3 per cent.
... 59-4
... 4-3
81

The ashes are therefore chiefly distinguished from
those of the mould fungi by the much larger quantity
of phosphoric acid present, this difference corresponding
entirely to the larger amount of albumen.

Nutrient
materials.

2. The Nutrient Materials of the Budding Fungi.

In investigating the mode of nutrition and the nutrient
materials of the yeast fungi, it is necessary to note that
these terms are not identical with fermentation and
fermentescible materials. Fermentation runs its course
to a certain extent independently of the nutrition of the
yeast ; it is not a necessary part of the tissue change of
the cells, but only forms an extension and complication
of the same, which it is better to disregard for the present
in attempting to ascertain the nature of the necessary
nutrient materials, a*nd the mode in which they are
used up by the yeast cells. This separation of the two
processes has only been properly carried out in the more
recent experiments, while on the other hand former
investigators always linked fermentation and the growth
of yeast together. The more recent investigations made

CONDITIONS OF LIFE OF THE BUDDING FUNGI. 519

by Niigeli, and more especially by Hansen, are also more
free from objection because they have paid great attention
to the purity of the cultivations of the yeast.*

As regards the nutrient materials required, the yeast Sources of
fungi agree very closely with the mould fungi, so that m
what was mentioned with regard to the latter applies
almost entirely to the former. A larger amount of
nitrogen is requisite for the yeast fungi in correspondence
with the larger quantity which they contain. The most
favourable source of nitrogen is the soluble and easily
diffusible albuminoid materials, and more especially
peptone ; but the place of the proteid substances may be
taken by ammoniacal salts, substituted ammonia, and
the other nitrogenous compounds mentioned in the case
of the mould fungi ; if, however, ammoniacal salts are
the only source of nitrogen the yeast cells appear to
undergo degeneration, their substance becoming richer
in fat and poorer in nitrogen ; and this degeneration
occurs still more readily if other conditions of life, such
as the presence of free oxygen, are also wanting (Niigeli).
Under circumstances otherwise equal peptone is about
four times better as a source of nitrogen than, for
example, tartrate of ammonia. With regard to the
nitrates there is an important difference between the
mould fungi and the yeast cells ; the nitrates are quite
unsuitable for the nutrition of the yeast, and cannot
serve as sources of nitrogen.

Carbon has the same relation to yeast fungi as to Necessity of
mould fungi ; the best source is sugar, and then mannite, carbon-
glycerine, tartaric acid, &c. In the case of mycoderma
vim, alcohol appears to be an almost necessary nutrient
material, and can at most be replaced by malic acid
(Schultzf). — With regard to the hydrogen, combined
oxygen, and sulphur there are no marked differences

* Compare Pasteur, Ann. de Chim. ft de PIn/s., (3) vol. 58.— Duclaux,
Theses present, a lafac. de sc. de Paris, 1865. — Dubrunfaut, Compt. rend.,
vol. 73.— Schiitzenberger, Compt. rend., vol. 78.— Mayer, Untersuchungen
•iiber die alkoholltche Gahrung, &c., Vti/B&.—Lcmdwirthgch. Versuchsstat..
vol. 14. — Mach, Anal, de Oenologie, vol. 4. — Niigeli, Theorie der Giihrung,
1879. — Untersuchungen iiber niedtre Pilze, 1882. — Hansen, Meddedelser
fra Carlsberg Labornloriet : Kopenhagen, 1879—1884.

f Cit. in Mayer, Gahrungschemie.

520 BIOLOGY OF THE MICRO-OKGANISMS.

between the yeast and mould fungi. Of mineral sub-
stances, potash, phosphoric acid, and calcium are indis-
pensable ; the presence of a considerable quantity of
acid phosphate of potash (about 20 per cent.) has a
markedly favourable influence on growth.

fJeeeoSxytgen°r The mould fuu& and ^east fungi benave very dif-
ferently as regards oxygen. On the whole the presence
of free oxygen exerts a very favourable influence on the
growth and multiplication of the yeast-cells ; when
brought into contact with water containing oxygen or
with oxy-hseinoglobin the yeast, as Schiitzenberger has
shown, takes up the oxygen very greedily ; and under
otherwise similar circumstances the largest quantity of
yeast is obtained when a continuous stream of air is
passed through the nutrient fluid. Multiplication of
the yeast can, however, occur without the access of
oxygen, but only when the other nutrient materials are
furnished in a suitable form, and when the yeast-cells
are able at the same time to cause fermentation. Thus
yeast grows actively without the presence of air in a
solution of peptone, or in a decoction of yeast containing
1 to 10 per cent, of sugar, and *5 per cent, of phosphoric
acid; its growth is less energetic when, instead of
peptone, meat extract, urea, or ammoniacal salts are
mixed with sugar ; and growth does not occur, or
only to a very slight extent, when no sugar is present,
or when its place is taken by other bodies, such as
glycerine or mannite, which do not so readily undergo
fermentation. In all cases the multiplication of the
yeast in the absence of oxygen goes hand in hand
with fermentation of the sugar, and the fermentative
activity seems to replace the action of the free oxygen.
This possibility of living without oxygen naturally in-
fluences also the occurrence and the habitat of the yeast ;
thus it can vegetate in the interior of fruits, provided
only that these contain fermentescible sugar, and that
the other conditions necessary for a development of its
fermentative activity are present.

Influence of With regard to the concentration and reaction of the
the concentra- material there are also some differences between mould

tion or the
material.

CONDITIONS OF LIFE OF THE BUDDING FUNGI. 521

and yeast fungi. The latter do not bear such marked
concentration of the nutrient mixture as do the mould
fungi ; the optimum of the amount of water is, however,
equally dependent on the nature of the other nutrient
materials. Nutrient materials which are not very suit-
able require as a rule a great dilution (salts of ammonia
must not be present in more than 1 per cent.), while
sugar, for example, may be present in the nutrient
mixture up to 85 per cent, without leading to cessation
of the growth.

With regard to the reaction, the yeast fungi resemble Thyeaction
the mould fungi in that they can bear a fairly markedly mixture.
acid reaction without harm ; but the upper limit of the
excess of acid is lower than in the case of the mould
fungi, so that by increasing the acidity of the material
(the addition of 5 per cent, of tartaric acid, or 1 per cent,
of phosphoric acid) the growth of the mould fungi, as
compared with that of the yeast fungi, is favoured.
Yeast seems to be very sensitive to an excess of alkali,
so that even traces of alkali can hinder growth. (Dumas,
Mayer.)

3. Other Conditions of Life of the Yeast Fungi.

Some of the other factors which can influence the energy
of growth of the fungi have also been investigated in the
case of yeast. — Light and electricity are, so far as ex- Action of hij?h
periments have gone, without influence on the growth Prcssure-
of the yeast : in like manner, according to experiments
by Certes and Cochin,* a pressure of 300 to 400 atmo-
spheres maintained for several days did not injure yeast ;
under these circumstances, in fact, it was still able to
break up sugar into alcohol and carbonic acid. Hoppe- Action of
Seyler has observed that mechanical movement of the
nutrient solution acts in an unfavourable manner on
yeast ; but this investigation was limited to the question
of the fermentative activity of yeast, and besides, the
cultivations were much contaminated with bacteria. On
the other hand, Han sent has demonstrated, in a scries of

* Compt. rend. soc. biol., 1884.

f Meddedelser fra Carhberg Lab., vol. i., part 2.

522

BIOLOGY OF THE MICRO-ORGANISMS.

Inflmnce of
tempt rature.

Influence of
fermentation

Concurrence
with other
fungi.

experiments which are much less open to objection, that
the beer yeast multiplies more readily when constantly
shaken than when kept at rest. The temperature has
an important influence on the development of the yeast.
The optimum appears to lie between 25° and 30° C. ;
but it depends to a certain extent on the composition of
the nutrient solution. Above the optimum the rapidity
of growth rapidly diminishes, and ultimately ceases at
about 53° C. ; below the optimum the diminution of the
growth occurs more slowly, and even slight vegetation
may take place a little above the freezing point.

The fermentative activity of those yeast fungi which
are able to excite fermentation forms a special factor of
considerable importance. It is a matter of experience
that the development of the yeast cells runs parallel
with the energy of the fermentation; farther, yeast
appears to multiply much more rapidly when sugar is
present in the nutrient solution than when materials,
such as glycerine, which cannot be broken up by the
yeast, are present. On the other hand, the latter sub-
stance is quite as good a nutrient material as sugar in
the case of other species which cannot excite fermenta-
tion ; and hence we may draw the conclusion that the
fermentative activity itself is able to supply a certain
amount of energy to the yeast cells which can be utilised
for their vegetative life (Na'geli.)

The simultaneous presence of other fungi, and the
concurrent growth with these, plays an important part
in the cultivation of the yeast fungi. The bacteria
more especially can, as the result of their more rapid
multiplication, very readily limit the development of the
yeast fungi ; here, however, the result is also dependent
on the sum total of the conditions of life which may be
more favourable for the yeast fungi, and may thus form
a substitute for the less energy of their growth. The
concentration and reaction of the nutrient medium is
here also of the greatest importance ; at times also the
temperature, higher degrees of which, for example, may
protect the yeast against many mould fungi, such as
penicillium. Fermentative activity also seems to exert

CONDITIONS OF LIFE OF THE BUDDING FUNGI. 523

a special influence on the concurrent growth of the
yeast. For example, if a very minute quantity of yeast
is introduced into a neutral saccharine nutrient solution,
and if no care is taken to exclude bacteria, the latter
generally multiply readily, and a very impure cultivation
of yeast is obtained, or one in which the bacteria are
in greatest numbers. If, however, we increase the
amount of yeast introduced up to a certain point — 1*7
grammes of dry yeast, or 10 ccm. of thick yeast, for
every litre of nutrient solution — the yeast alone multi- .
plies, and the bacteria scarcely develop at all. It can be
shown that this phenomenon does not depend on the
excretion of materials hurtful to the bacteria by the
yeast, and we must therefore suppose that it is the
fermentative movement which hinders the multiplication
of the bacteria. In accordance with this we have the
observation that we are the more likely to obtain a
relatively pure cultivation of yeast the quicker and more
completely the fermentation occurs after the organisms
are introduced, and that it is thus independent of the
number of the fission fungi which have obtained
admission at the same time. Thus we have the ex-
planation why the ordinary beer yeast is usually fairly
(but never quite) free from bacteria, andawhy, when the
brewing process is properly carried out, we need not fear
disturbance by the development of bacteria (Nageli).*

4. Conditions of Spore Formation and Spore Germina- Conditions of
tion.— In contrast to the higher plants, and also to the (

mould fungi, the yeast and fission fungi are distinguished
by the possession of a very great tendency to utilise the
nutrient materials for the continuous production of
purely vegetative cells without the formation of any true
fructification. In suitable nutrient media the yeast fungi
constantly form new cells by budding, and the bacteria
divide continuously like an enormously developed tree
without fruit. It is only when the nutrient conditions
become markedly unfavourable, and when one of the
most important nutrient substances begins to disappear,
that there is an interruption in the ordinary mode of

* Nageli, Theorie der Gdhrung, 1879, p. 77.

524 BIOLOGY OF THE MICRO-ORGANISMS.

multiplication; the fungus then converts the remains of
the nutrient material at its disposal into a more durable
cell, which can survive after the exhaustion of the
nutrient material, and can grow again in new nutrient
soil even after a long interval.

In the case of the yeast, the conditions necessary for
the formation of spores are furnished when the nutrient
substratum is very poor in nutritive materials, more
especially in sugar, or is very dilute, while at the same
time (as in the case of the mould fungi) free access of
the oxygen of the air is permitted, and evaporation is
limited. If yeast is spread out on thin slices of boiled
carrot, or on moistened plaster, and then kept in a moist
chamber, the formation of spores in the cells, as described
on page 147, occurs in the course of a few days; the
same result is obtained if a solution of sugar containing
yeast is more and more diluted by the daily addition of
water. According to Hansen,* spore formation is readily
observed on microscopic slides covered with a layer of
nutrient jelly, if the temperature is not too high; in
like manner yeast water containing air is also a favour-
able nutrient medium. — The minimum of temperature
at which spore formation has been observed is between
+ 1° and 3° C., the maximum at 37^° C.— The spores
can be kept for a long time, and can be dried without
losing their power of sprouting.

Germination The conditions of the germination of these spores are
similar to those mentioned in the case of the spores of
the mould fungi. The presence of nutrient materials is
not necessary for the commencement of germination ; on
the other hand, moisture and free oxygen are absolutely
essential, so that in respect of the latter there is a
marked difference between the vegetation and the fruc-
tification of yeast. Further, the temperature has an
important influence, but this has not as yet been quanti-
tatively determined, t

* I. c., vol. ii., part 2.

f Russ. Annalen der Oenologie, vol. ii. — Botan. Zeit., 1873.

CONDITIONS OF LIFE OF THE FISSION FUNGI. 525

(e) Conditions of Life of the Fission Fungi.
1. Chemical Composition of the Fission Fungi.

In order to isolate the fission fungi from the nutrient Chemical corn-
fluid, it is well to follow Nencki's* method, by render-
ing the fluid acid by the addition of 2 to 3 per cent, of
free hydrochloric acid, and then boiling it. The bac-
terial masses are thus coagulated, and may be easily
obtained by filtration ; we must, however, avoid nutrient
solutions, from which albumen might be precipitated
by this method. In a 2 per cent, solution of gelatine
(and also in a solution of mucate of ammonia) Nencki
found the following composition, in the case of the
bacteria, corresponding to the different stages of their
development, beginning with the formation of a very
gelatinous zooglea : —

Water.

Albumeh
Fat
Ashes
Undetermined

Pure zooglea
mass,
84'81 per cent.

Zooglea mass
with bacteria,
84'26 per cent.

Adult bacteria
83"42 per cent.

84-20 per cent,
6.04

472 „
5-04 „

In the substance free from water.

8576 per cent.
7'89
4-20 „
2-15

87-46 per cent.
6-41

3-04 „
3-09

The albuminous material is to a great extent formed
of a body which differs from other proteid substances
in some of its reactions — for example, it is not precipi-
tated by alcohol — and especially in its elementary com-
position; it has been called by Nencki my co-protein.
This substance contains 52'32 per cent. C., 7'55 per
cent. H., 14*75 per cent. N. ; no sulphur, and no phos- my co-protein,
phorus. On heating it with caustic potash, the following
substances were obtained : phenol, skatol, indol, large
quantities of fatty acids especially valerianic acid, and
leucine.t

* Nencki, Beitrage zur Biologie der Spalfpitze, 1880.
f Nencki's Journ.filr prakt. Chem., N.F., vol. 23.

526

BIOLOGY OF THE MICRO-ORGANISMS.

In the case of some pathogenic organisms, numbers
have heen obtained which differ considerably from the
above. Spores of the anthrax bacilli cultivated in nu-
trient gelatine in large vessels, containing 1 to 2 litres,
and collected after three weeks growth, showed,
according to Nageli, no myco-protein, but a peculiar
albuminoid body, which he has called anthrax-protein,
readily soluble in alkalies, but quite insoluble in water,
acetic acid, and dilute mineral acids; it contains no
sulphur.*

Brieger t has obtained the following results with regard
to Friedlaender's pneumonia bacilli, which he culti-
vated on nutrient gelatine. He found 84*2 per cent, of
water; 1*74 per cent, of fat in the dry substance; in
the dry substance free from fat 30'13 per cent, of ashes ;
and in the dry substance free from fat and ashes
9*75 per cent, of nitrogen. — The organic substances
gave on the whole the reactions characteristic of protein,
but they were not identical with Nencki's myco-protein.
— Vandevelde J found on analysis of bacillus subtilis
no cellulose, but nuclein.

According to these results the relation between the
albuminoid substances and the material resembling cellu-
lose, which in the case of the yeast fungi was in favour
of the former, is still more altered in the same direction in
the case of the fission fungi, so that the non-nitrogenous
materials pass completely into the background, and
albuminoid substances form almost the whole substance
of the fission fungi. There are, it is true, analyses of
other fungi by Nageli and Low, which differ markedly
Contradictory in part from the above results. A growth of micrococci
cultivated in tartrate of ammonia gave 10'65 per cent, of
nitrogen and 6'94 per cent, of ashes; on the other hand,
the vinegar plant, which consists of a tough jelly, in
which short rods are embedded, yielded 98*3 per cent,
water, and in the dry substance only 1*82 per cent.
N. and 3*37 per cent, ashes, so that in this case also

* (hem. ber., vol. xvii., p. 260o.
t Zeitschr.f. physiol. Chtm., vol. is.
J Jbid., vol. viii.

Relation
between
nitrogen and
carbon.

CONDITIONS OF LIFE OF THE FISSION FUNGI. 5*27

the chief body present must be the non-nitrogenous
cellulose material.

Durin and Scheibler* also observed that the mem-
brane of Leuconostoc mesenterioides chiefly consisted
of a hydrocarbon closely allied to cellulose. Further
analyses must show us in what way we are to explain
these marked analytical differences, and what their
value is.

The ashes of the fission fungi have not as yet been Ashes.
accurately analysed. Brieger found in the ashes of the
pneumonia bacilli phosphate of lime, phosphate of mag-
nesia, sulphate of sodium, and chloride of sodium. As
a whole, the ashes of the fission fungi have probably an
analogous composition to those of the yeast.

In some species of fission fungi chemical substances
are always, or at times, present which do not belong
to the ordinary constituents of the , bodies of these
organisms. For example, substances resembling gran- Rarer
ulose occur in bacillus butyricus and in Vibrio rugula
before the formation of spores, also in bacillus Pasteur-
ianus (Hansen) and in Leptothrix buccalis, and these
may be demonstrated by their blue colouration by iodine.
To this class of substances belongs the ruguline Sulphur
sulphur found in some species of beggiatoa ; further,
some specific dyes, the majority of which, however, do
not appear to be deposited in the wall or cell contents
of the organisms.

2. The Nutrient Materials of the Fission Fungi.

As a whole, the nutrient materials and conditions of Nutrient
life of the fission fungi resemble those of the mould matei'ial«-
fungi; the different species, however, differ in their
requirements so much, that much more detailed investi-
gations are necessary. We must therefore await farther
researches before we can writs a complete account of
this subject.

As a rule these fungi obtain nitrogen best from diffu- Sources of

nitrogen.
* Quoted from de Bary.

528 BIOLOGY OF THE MICRO-ORGANISMS.

sible albuminoid materials.* Ammoniacal salts are not
so suitable, but are better borne than in the case of the
yeast fungi. The remaining nitrogenous compounds
appear to have the same relative value as in the case of
the mould fungi ; according to Niigeli, the nitrogen can
also be obtained from nitrates, and in the experiments in
question it was possible to follow the gradual reduction
of the nitric acid to nitrous acid, and finally to ammonia.

Beduction of This reduction of nitrates by bacteria has been recently
observed by Gayon and Dupetit, Deherain, Maquenne,
and Springer. Anaerobic organisms similar to or iden-
tical with bacillus butyricus when they set up a fermen-
tation, combined with the development of hydrogen,
seem to cause reduction of nitrates with formation of
oxide of nitrogen. This was also the case with certain
aerobes, and to a less extent with the bacilli of chicken
cholera, anthrax, &c.*f- In all these experiments, how-
ever, it is probable that the nitrates did not suffice to
provide the necessary oxygen for the fission fungi, but
that reduction was a secondary phenomenon, caused by
other products of the tissue change or fermentation, and
only accompanying the true tissue change of the bacteria.

carbon* °f ^^e SUPP^ °^ carDon ^s obtained not only from sugar

but also from bodies similar to it, from glycerine, and
especially from the various salts of fatty acids, such as
the alkaline salts of tartaric acid, citric acid, malic acid,
mucic acid, lactic acid, acetic acid, &c. ; even those
compounds which act, when markedly concentrated, in
a decidedly poisonous manner on the bacteria can be
utilised in a very dilute state as sources of carbon
supply, for example, carbolic acid, salicylic acid ; further,
aethylic alcohol, which forms the most favourable nutrient
medium for the vinegar fungus, and which can be present
in the nutrient solution up to 10 per cent. It is remark-
able that, according to Pasteur's observations, it is only

* See more especially Nageli, I.e. — Cohn, Beitriige, vol. i., Heft 2. —
Bucholtz, Arch.f. Exper. Path., B. 7, S. 81.— Mayer u. Knierim, Landw.
Versuchsstat., vol. 16 (Essigpilz).— v. Jacksch (Harnstoffpilz), Zeitschr.
f. physiol. Ckemie, vol. 5.

t Gayon and Dupetit, Compt. Rend., vol. 95. — Deherain and Ma-
quenne, ibid., and vol. W.—Bult soc. c/iim, 2, 3D.— Springer, Chew., Ber.,
vol. 16.

CONDITIONS OF LIFE OF THE FISSION FUNGI. 529

that form of tartaric acid which turns the polarisation to
the right which can he taken up by hacteria.

In the case of some hacteria, the most favourable
nutrient conditions have been more accurately deter-
mined; for example, by von Jacksch* for micrococcus
urea, and by Hueppe t for the lactic acid bacilli. Micro- Nutrient
coccus ureae can, for example, obtain the necessary ™e*e/sary for
nitrogen and carbon from nutrient solutions containing ™°™coccus
succinate, lactate, malate, tartrate, or citrate of ammonia,
from glycocoll, leucine, asparagine, salts of asparagine,
creatine, benzoate of ammonia, hippurates, and peptone.
On the other hand, the following were useless as sources
of nitrogen and carbon : formate, acetate, butyrate,
oxalate, and salicylate of ammonia, and acetamide.

In the case of bacterium lactis, carbon is best obtained For bacterium
from milk sugar, cane sugar, mannite, and dextran ;
the best source of nitrogen was peptone, or among the
salts, tartrate of ammonia. Nitrates were quite unsuit-
able as sources of nitrogen. The most favourable pro-
portion of the nutrient salts was 0*2 — 0'5 per cent, of
acid phosphate of potash, + 0'05 to O'l per cent, of
sulphate of magnesium -4- 0'015 — 0'025 per cent, of
chloride of calcium ; this mixture could be replaced by
1 per cent, of extract of meat.

These numbers are, however, only applicable to these Difference as
special cases. The more accurately the various species nuSient^e-
of bacteria have been studied during the last few years, quirements of

* . . '' ' the different

the more have differences in the nutrient requirements species of
of the different species been observed. Some require bact€
large quantities of certain albuminoid substances, and
only permit a variation in the composition of the nutrient
material within very narrow limits ; others permit a
greater variation in the nutrient materials, which, how-
ever, must be fairly concentrated and composed of
complex molecules. Others, finally, prefer very dilute
and simple solutions in which one can scarcely recog-
nise anything of nutrient value. Among the bacteria Contrast
which are most sensitive in this respect are chiefly the ^t^o^nic16

bacteria and

* Zeitschr.f. physiol. Chem., vol. 5. J

f Mitth. a. d. Kais. Ges., vol. ii. water

34

530

BIOLOGY OF THE MICRO-ORGANISMS.

Formation of
ferments by
bacteria.

Necessity for
free oxygen.

Pasteur's
division into
aerobes and
anaerobes.

pathogenic forms, which can only grow on certain
hosts, and which refuse to live on any other living
or dead substratum (such as the spirilla of relaps-
ing fever, or the bacilli of leprosj^), or which, at any
rate, require blood serum, or mixtures containing soluble
albumen, peptone, and salts. The greatest contrast to
these bacteria is formed by those which have been
described by Bolton* (bacillus erythrosporus, micro-
coccus aquatilis, &c.), which find sufficient nutrient
material to enable them to grow in enormous numbers
even in pure distilled water. As in all their other vital
functions, so here, the bacteria present conditions which
render it impossible to treat them in a schematic manner.
The number of suitable nutrient materials is increased
in the case of many species of bacteria by the fact that
they produce ferments which can transform insoluble
substances into soluble and diffusible ones. Coagulated
albumen, solidified gelatine, starch, and di-saccharates
can be transformed by means of peptonising, diastatic,
and inverting ferments into soluble and assimilable
nutrient materials. As regards this production of
ferment also the various species of bacteria show great
differences both qualitatively and quantitatively.

The bacteria also behave very differently with regard
to oxygen. Pasteur was the first to observe that there
were bacteria which did not require free oxygen for their
life and multiplication, but, on the contrary, could earn-
on their vital functions in the absence of oxygen, and,
indeed, the presence of that gas might interfere with
their multiplication and their vital phenomena. Pasteur
gave effect to this distinction by his division of the bac-
teria into " aerobes " and " anaerobes." The surprising
fact that life could occur without oxygen was also soon
confirmed by other observers, such as Nencki, Praz-
mowski, Rosenbach, &c., and though Gunning asserted
that in none of these experiments was the oxygen
sufficiently removed, and thus no complete anaerobiosis
existed, nevertheless these objections cannot hold ground
against the recent experiments by Nencki and Lachewicz ;

Gott. hyg. Institut. Mitgetheilt in Zeitsckr.f. Hygiene, vol. i.

CONDITIONS OF LIFE OF THE FISSION FUNGI. 531

Nencki convinced himself that in the cultivation appara-
tus ferrocyanideof iron and reduced haemoglobin remained
unaltered, and that thus we had to do with complete
absence of oxygen so far as this can be confirmed by
chemical means.

Nageli has drawn especial attention to the great im- Replacement

. . , - ,. ,. ., . f ••• of the oxygen

portance of the fermentative activity in reference to the by the

need for oxygen on the part of the fission fungi; tf
fermentative action is going on the access of oxygen
becomes unnecessary ; if the bacteria in question are
unable to excite fermentation, or if it so happens that
they live under conditions in which no active fermentation
can occur, free oxygen becomes absolutely essential for
their development.

Engelmann has further shown that the motility of influence of
the bacteria is influenced to a very great degree by the oxygen on

„ ., , . -,. tt •'•ii • movement.

tension of oxygen in the nutrient medium. Spirilla are in
this respect much more sensitive than any other species
of motile bacilli ; the latter assemble at the margin of
any air bubble which may be present within a drop
of nutrient fluid; spirilla, on the other hand, remain
at some distance from the margin of the air bubble,
and only approach it when the amount of oxygen
in the nutrient solution has become diminished. In
this species of bacteria too great a quantity of oxygen
has also a similar effect in causing the cessation of
movement. The lower limit of necessary oxygen was
very low in this species of spirilla ; if they were placed,
along with micro-organisms containing chlorophyll, in
a medium which was free from oxygen but illuminated
with white, red, or yellow light, the spirilla. at once
collected at those parts where traces of oxygen were
developed by the chlorophyllous cells.

More recent investigations by Liborius* have added to
our knowledge as regards the need for oxygen by the
bacteria, and have more especially shown that the
anaerobic organisms can live and multiply without
exercising any simultaneous fermentative activity.
According to Liborius' investigations we may divide the

* Gott. hyg. List. See Zeifschr.f. Hygiene, vol. i.

532

BIOLOGY OF THE MICRO-ORGANISMS.

Obligatory
anaerobes.

Facultative
anaerobes.

bacteria into three groups, which differ in an important
manner as regards their necessity for oxygen. In
the first place, we have a group of what may be
termed " obligatory anaerobes," which only grow when
the oxygen is removed as completely as possible from
the nutrient medium, at any rate when it can be no
longer demonstrated by the ordinary chemical means.
To this group belong, for example, the bacilli of malig-
nant redema, bacillus butyricus, bacillus muscoides,
bacillus polypiformis, &c. Some of these organisms
have the property of exciting fermentation in certain
fermentescible materials, and then they are able to
multiply in large numbers in correspondence with the
intensity of the fermentation. In the case of other
species no fermentative activity has as yet been made
out. The fermentations set up by these anaerobic
organisms can be arrested by the admission of oxygen,
just as is the case with the growth of the same organisms
in non-fermentescible substrata.

A second group is formed by what we may term the
" facultative anaerobes." These bacteria grow best and
most quickly when the entrance of air is permitted, but
they are also capable of developing slowly when air
is excluded. The degree to which the growth is in-
fluenced by the exclusion of oxygen varies very much in
the different species. On the whole an artificial increase
in the tension of the oxygen is injurious to the bacteria
belonging to this group ; but here also the degree of
sensitiveness varies in the different species. Among the
very numerous organisms which belong to this group
we may mention more especially the various pathogenic
organisms, for example, staphylococcus, streptococcus,
bacillus septicus cunic., bacillus sept, crassus, bacillus
anthracis, bacillus typhi. abdom., bacillus pneumonia?,
spirillum cholerse asiatica?. In this group also the
majority of the bacteria do not require to exercise fer-
mentative activity in order to live without oxygen. In
many of them their behaviour, when fermentescible
materials are absent, has not as yet been tested ; never-
theless simultaneous fermentative activity favours the

CONDITIONS OF LIFE OF THE FISSION FUNGI. 533

anaerobric growth of these bacteria to a marked degree.
In the case of some organisms, for example, bacillus
lactis aerogenes (Escherich), it has been demonstrated
that they can only exist without air when fermentescible
material is present, and fermentation is going on. —
The fermentations set up by these organisms are ap-
parently not injuriously affected by the access of oxygen,
but on the contrary are favoured.

In contrast to these groups we have a third, which is Obligatory
composed of " obligatory aerobes " ; these organisms can- aerobes-
not grow when air is excluded, even though they could
otherwise excite fermentation. Their growth is inter-
fered with by any marked diminution in the amount of
air, and under these circumstances one or other of their
functions may cease (for example, the production of
colouring materials, of ferments, &c.) ; on the other
hand, their life and growth is much favoured by artificial
increase in the tension of the oxygen. To this group
belong, for example, bacillus subtilis, bacillus ae'ro-
philus, &c. Nevertheless, within this group there are
marked differences as regards the quantity of oxygen
necessary, so that we can only lay down a general law,
viz., tbat each of these species of bacteria requires a de-
finite amount of oxygen. The fermentative action of the
bacteria belonging to the group of obligatory aerobes is
without exception favoured by the access of air ; for ex-
ample, the lactic, and more especially the acetic, fermen-
tation. According to Hoppe-Seyler,* a continued and
marked impregnation of the nutrient medium with air
has a favourable action on the development of many
putrefactive bacteria, as well as on the course of the
putrefactive fermentations set up by them, and hence
we may conclude that some of the bacteria which can
excite fermentation belong to the group of aerobes, while,
on the other hand, many obligatory aerobes also take
part in this process.

We can say very little which is of general appli- concentration
cability as regards the most favourable proportions of of the nutrient
the individual nutrient materials, on account of the

* Zeitschr.f. physiol Chem., vol. 8, p. 214.

534 BIOLOGY OF THE MICRO-ORGANISMS.

very great differences in the requirements of the dif-
ferent species of bacteria. On the whole, the amount of
water in the nutrient material must be very great, and
the concentration slight. Fermentescible substances
can be protected against the invasion of bacteria by the
removal of a relatively small quantity of water, while
they still remain a favourable soil for the growth of the
yeast fungi, and more especially of the mould fungi.
Very little has been ascertained as to the limits of con-
centration, for this must vary according to the nature
of the nutrient materials ; quite as little is known as
regards the optimum of the amount of water. That the
latter can as a rule vary within wide limits is evident
from the fact that bacteria can be cultivated equally
well on semi-solid nutrient soils containing about 80
per cent, of water, in concentrated fluids containing
5 to 10 per cent, of solid constituents, and in very
dilute solutions containing scarcely more than traces of
nutrient substances.

Eeaction. Excess of acid or alkali may be either injurious or

favourable to the development of the bacteria ; the first,
however, interferes most readily with the growth. In
this respect there is an important difference between
many of the bacteria and the mould and yeast
fungi ; and hence in the acid reaction of the nutrient
medium we have an excellent means of protecting the
cultivations of the latter organisms against the entrance
of numerous species of bacteria. Many bacteria, for
example, bacillus subtilis, anthrax bacilli, &c., are very
sensitive to slight excess of acid ; but on the other
hand there are bacteria, such as bacillus butyricus or
the acetic bacterium, which can bear a very marked acid
reaction without injury ; indeed, many only grow when
there is a certain excess of acid in the nutrient medium
(for example the bacillus of blue milk, and the bacterium
of acetic acid which only grows when at least 2 per cent.
of acetic acid is present) . Hence an excess of alkali is
hurtful to these particular bacilli, while as a rule it has
by no means such an injurious effect on bacteria as the
free acids ; indeed, some organisms, for example the

CONDITIONS OF LIFE OF THE FISSION FUNGI. 535

micrococcus urese, can bear an extremely high degree of
alkalinity. Some bacteria show such indifference with
regard to the reaction of the nutrient medium that they
may commence their development on a markedly acid
soil, then convert the reaction by the products of their
growth into an alkaline one, and continue to grow in the
presence of a marked excess of alkali.

3. Other Vital Conditions of the Bacteria.

According to the experiments which have as yet influence of
been made light does not appear to be one of the 1?
general conditions of life of the bacteria ; the observation
made by Engelmann that in the case of one species
of bacterium (bacterium photometricum) the swarming
movements were dependent on the light does not
with certainty refer to a bacterium but more pro-
bably to a fission alga.* TVith regard to the injurious
action of sunlight, see Part 5. In like manner elec- Electricity,
tricity, so far as it comes into play under normal
conditions, is without any influence ; strong currents,
however, interfere with the development of the culti-
vations, t Alterations in the pressure are borne by Highpressur
many bacteria in a remarkable manner, as has been
shown, for example, in the case of the bacillus butyricus ;
Certes has also observed that putrefactive processes
go on even under a pressure of 350 to 500 atmo-
spheres, and that anthrax bacilli retain their virulence
after exposure for 24 hours to 600 atmospheres.

To a certain extent rest and the absence of mechanical Mechanical

1 /> . f .-, movement.

movement appear to be of some importance for the
fission fungi, although the experiments made in this
respect have not given entirely uniform results. A con-
tinuous, gentle, flowing movement of the nutrient media
does not appear to hinder the development of the fission
fungiij: ; on the other hand, it was observed that con-
tinuous and marked shaking of the fluid, such as is set

* Pfliiger's Arch., vol. 26, p. 537.— Botan. Zeitfj., 1882.
t Cohn and Mendelssohn, Cohn's Beitrdge, vol. iii., part 1.
X Hoppe-Seyler, Festschrift u. s. w. "Ueber die Einwirkung des
Sauerstoffs auf Gahrungen," 1881.

536 BIOLOGY OF THE MICRO-ORGANISMS.

up by a special motor,* or by sounds of sufficient intensity
conducted through the nutrient solution,! have a distinct
disturbing influence on development. More recently,
however, somewhat different results have been obtained
in a fresh series of experiments. J

Influence of Further, a certain medium temperature is a necessary
condition for the development of the bacteria. Never-
theless, the optimum of temperature, as well as the
upper and lower limits, are quite different in different
species of bacteria, and are also dependent on the other
conditions of life, more especially on the composition of
the nutrient material. According to Eidam's experi-
ments, with regard to the development of bacterium
termo in Cohn's nutrient solution, growth begins at
H-5i° C., increasing at first slowly as the temperature
rises, and then quickly from 10° C. upwards, attains
the optimum between 30° and 35° C., and very
rapidly diminishes, and ultimately entirely ceases at
40° C.§ In the case of the acetic bacterium the
optimum lies between 20° and 30° C. ; below 10° C.
growth goes on extremely slowly, and it diminishes
rapidly above 35° C., and ultimately ceases a few degrees
higher.il The tubercle bacillus grows, on the other
hand, only between 30° and 41° C., best at 37° to
38° C. In the case of the bacillus subtilis Brefeld
found that the growth was very slow at 6° C. ; at 12'5° C.
4 to 5 hours elapsed between each new sub-division of
the rods; at 25° C., j-hour; at 30° C., J-Lour. From
these examples it is sufficiently evident that the various
species of bacteria vary markedly with regard to their
relation to temperature, and it can only be said with
regard to the relation of temperature to the mould and
yeast fungi, that as a rule the most favourable tem-
perature is less than in the case of the bacteria, in
which the optimum lies nearer the temperature of the
human body.

* Horvath, Pfliiger's Arch.f. PhysloL, vol. 17.

t Eeinke, Ebenda, vol. 23.

j Tumas, Petersbnrger med. Woch., 1881.

§ Eidam, Cohn's Beitrage, i., 3, p. 209.

|| Mayer, Giihrungschemie, p. 178.

CONDITIONS OF LIFE OF THE FISSION FUNGI. 537

The fermentative activity in all probability plays the influence of
same part with regard to the life of the bacteria as it tive activity,
does in the case of the yeast fungi. In the case of the
bacteria which can set up fermentation, the fermentative
activity appears to favour the growth of the organisms as
soon as a certain intensity of the fermentative action has
been attained, while the development of other bacteria
which may be present at the same time is hindered.
Hence a certain intensity of fermentative activity exerts
a marked influence on the concurrent growth of various
species of bacteria, and on the production of pure
cultivations.

As a rule, in concurrent growth with mould and yeast Concurrent
fungi, the bacteria have an advantage in their ex- ^h
tremely rapid multiplication, and in the very energetic
manner in which they use up the nutrient materials.
It is only when some of the conditions as regards the
nutrient substratum are selected in such a manner that
they exert an unfavourable influence on the development
of the bacteria, while they at the same time permit the
unhindered growth of the other classes of fungi, that it
is possible for the latter to take possession of the
nutrient medium and to exclude the bacteria. As has
been mentioned, the concentration and reaction of the
nutrient material are the chief means by which the
growth of the yeast and mould fungi, as compared with
that of the bacteria, may be favoured. — Among the
bacteria themselves various factors, more especially
reaction, temperature, relative amount of the individual
nutrient materials, and more especially of the nitro-
genous compounds, the tension of the oxygen, &c., are
the chief means by which one or other species may
succeed in growing in excess, and ultimately in almost
entirely gaining the upper hand.

4. Conditions of Spore Formation and Spore

Germination.

To a still higher degree than the yeast fungi the Spore
bacteria appear able to utilise suitable nutrient materials

588 BIOLOGY OF THE MICRO-ORGANISMS.

for the simple multiplication of cells. "What the con-
ditions are which must be present in order to set up the
phenomena of spore formation, a process on the whole
of rare occurrence, have not as yet been fully worked out.
From analogy we may suppose that the exhaustion or
vitiation of the nutrient medium forms the necessary
condition for the commencement of this act ; and as a
matter of fact this seems to be the case in many species.
Apparent exceptions have as yet been observed in bacillus
butyricus, bacillus subtilis, anthrax bacilli, &c. ; never-
theless, in the spore-bearing cultivations of these bacteria
it is possible that one or other of the nutrient materials
has become diminished to such an extent as to suffice
for the introduction of the process of spore formation,
or the nutrient substrata may have become sufficiently
saturated with the noxious products of tissue change of
the bacteria to render them imperfect as nutrient media.
It is possible that further observations will enable us
to formulate the conditions of spore formation in the
bacteria in a similar manner to those of the yeast fungi ;
in that case, however, the marked differences between
the individual species of bacteria must of course be
taken into account. The oxygen exerts a peculiar effect
on the spore formation of the bacteria. While in
the case of the mould and yeast fungi oxygen must have
free access, the bacteria are divided in this respect into
two groups. The majority also appear to require
oxygen for the formation of spores, and Prazrnowski
pointed out that it is characteristic of these forms that
they are non-motile during the stage of fructification.
The true anaerobes, however — this has been demonstrated
with certainty as regards bacillus butyricus — can only
fructify in the absence of oxygen, and continue to move
during the stage of fructification.

The temperature exerts a marked influence on the
process. Koch* has shown, in the case of anthrax bacilli,
that a temperature of at least 16° C. is necessary for the
formation of spores; and under these circumstances
limited formation of spores did not occur till after seven

* Mittheilimr/en a, d. Kais, Ges. Amt.} p. 05.

CONDITIONS OF LIFE OF THE FISSION FUNGI. 539

days. At 21° C. spores had formed after 72 hours, at
25° C. after 35 to 40 hours, and between 30° and 40° C.
after about 24 hours ; the best and strongest cultivations
were obtained between 20° and 25° C. In the case of
bacillus subtilis spore formation did not occur below
6° C., at 18-75° C. it required two days, at 22'5° C.
one day, and at 30° C. 12 hours.

As regards the germination of spores, and the neces- Germination
sary conditions for that act, we have as yet no detailed
observations. A certain amount of water and a fairly
high temperature, differing, however, according to the
species, must be reckoned as absolutely essential con-
ditions. In the case of bacillus subtilis, the optimum
of the temperature for germination lies between 30° and
35° C., and in the case of anthrax bacilli at about 35° C.

As regards oxygen it has been made out in the case of
the spores of some bacteria, for example of bacillus
butyricus, that it may actually hinder the occurrence of
germination ; while, as a rule, the entrance of oxygen is
just as necessary for the sprouting of the great majority
of the spores of bacteria as it is for those of yeast and
mould fungi, and as it is for the other functions of the
same bacteria.

540

PAET IV.

VITAL ACTIONS OF THE LOWER FUNGI.

The vital HAVING discussed the conditions necessary for the
life of the fungi with special reference to the nutrient
materials which must always be present in their sur-
roundings, it is the ohject of this part of the work to
show how the nutrient materials are taken up, the trans-
formations which they undergo in the body of the
organisms, in what manner growth takes place, and how
the energy, which is necessary in order to enable the
fungi to carry out their other functions, is obtained
from transformation of the material. It is evident that
this subject, which has also to do with, and to explain as
far as possible, the special activity of the fungi in ex-
citing fermentation and disease, forms one of the most
important chapters on the subject of the fungi.

Proposed plan The tissue change and development of energy of the

of treating the , £ . „ . r . ,, . QJ ,. ,

subject. mould, yeast, and fission fungi agree in their essential

points to such an extent that it has not appeared
necessary to treat of the three classes separately in this
chapter. The behaviour of the fission fungi, as being
the most important group from a hygienic point of view,
is taken as a groundwork, and it is only at certain
places that attention is specially directed to differences
in the behaviour of the other chief groups.

In the first place, we shall make a short general review
of the tissue change and development of energy of the
lower fungi, closely following what is known as to the
biology of the higher plants. We must then discuss
the individual phases of the vital activity of the fungi,
the assimilation of nutrient materials, and the changes
which they undergo in the body, the development of

DEVELOPMENT OF ENERGY IN THE LOWER FUNGI. 541

energy, and the products of tissue change and the
excreta. Among the latter the isolated ferments and
the ptomaines require a more detailed consideration.
Closely allied to these we have those two peculiar, and
for hygienic purposes important, phases of the vital
activity -of the fungi, viz., the fermentative activity and
the development of disease.

1. Review of the Tissue Change and Development of
Energy in the Lower Fungi.

For the development of those movements and
alterations of material particles, which make up the
life of the vegetable cell, a certain amount of energy
must in the first place be set free ; without this these
movements, and therewith the life of the plant, would
cease. A small fraction of the necessary energy is
obtained by osmosis; by far the greatest portion is,
however, supplied to the plant by the splitting up of
complex chemical compounds, and by regrouping of
the atoms in more stable compounds, in other words
by similar transformations to those which occur in the
animal body, and which then give rise to the energy
which is necessary for the various functions of the
animal economy. The vital processes in vegetables Tissue change
and animals differ only in the fact that the compounds
to be broken up are taken up by the animal bodies in j
an unaltered condition, while in the case of vegetables plants,
they must first be built up from more simple materials by
means of the chlorophyll apparatus ; in the lowest forms
of plants, viz., in the fungi, however, this preparative
apparatus is absent, and the materials are taken up in
the form of relatively complex molecules. What, how-
ever, is absolutely necessary, and common to the life
of the cells of animals, vegetables, and fungi, is the
decomposition of complex organic compounds accom-
panied with the liberation of energy.

These decompositions are carried out by means of the Decomposi-
living protoplasm. The latter can apparently, like a

542

VITAL ACTIONS OF THE LOWER FUNGI.

Intra-molecu-
lar respira-
tion.

Decomposi-
tion when
oxygen is
admitted.

ferment, gradually split up large quantities of suitable
complex compounds. We do not yet know accurately
the nature of the chemical bodies directly concerned in
this action of the protoplasm, nor in what way decom-
position takes place ; it is probable that the compounds
are nearly allied to the proteid materials, but are more
complex. As products of decomposition we constantly
observe carbonic acid, and also some other materials
which will be mentioned below. We may, however,
conclude from the amount of heat which becomes free
at the same time, although it is trivial, that the trans-
formation chiefly takes place in such a way that a more
complete union of the atoms and greater saturation of
the affinities, with consequent liberation of energy,
results.

This whole process, which is evidently the primary
and true cause of life, is usually spoken of as "intra-
molecular respiration." For this process the access of
oxygen is unnecessary, on the contrary it is characteristic
of it that all vegetable cells can continue to live and
breathe for a time without oxygen, and split up carbonic
acid and produce heat. If substances capable of under-
going decomposition are still present in the living
protoplasm, their decomposition is sufficient to furnish
the necessary energy for the other processes which
take place in the protoplasm, and it is only after a
considerable time that there is such a deficiency of
energy as to lead to the cessation of movement and
life.

Although, therefore, the intra-molecular respiration
is the chief and primary cause of development of energy
in the plant, the energy so obtained does not suffice
permanently to supply the whole amount required.
This is usually only obtained when oxygen has free
access, and when it takes part in the respiratory process.
The compounds broken up in the protoplasm furnish,
in addition to carbonic acid, a series of other products
which readily enter into combination with oxygen. Thus
extensive oxidations occur, and accordingly a more
marked development of vital energy which completely

DEVELOPMENT OF ENERGY IN THE LOWER FUNGI. 513

and permanently suffices for the vital processes. The
amount of energy is, however, regulated much less by
the amount of oxygen present than hy those processes
of decomposition in the protoplasm by the intra-
molecular respiration, which sets up and governs the
respiration by means of free oxygen.

The whole respiratory process, whether occurring Destructive
with or without oxygen, is evidently of a destructive tive tissue a"
character, and it is absolutely necessary that a constant chanse-
supply of new material should repair the deficiencies
which occur as the result of the decomposing activity of
the protoplasm and the oxidising action of the oxygen,
processes which furnish for the most part gaseous and
combustible products. As, however, those materials
which can be broken up in the protoplasm never
exist nor are taken up as nutrient materials, it is
evident that there must be a special process of assi-
milation, which consists in the absorption of the nutrient
materials present, and their transformation into com-
pounds suitable for decomposition, and which thus
stands in marked contrast to the destructive respira-
tory process. As a rule the part played by the
assimilatory process is in excess of the destruction,
and thus leads to the deposit of new protoplasm, and
the growth and multiplication of the cells. This is the
portion of the tissue change which usually alone strikes
the e}^e, and leads us very readily to overlook the fact
that, apart from the new formed material, large quan-
tities of the nutrient substances taken up undergo de-
composition in the protoplasm, and are burned up by the
oxygen.

The tissue change of the lower fungi must evidently
go on in an exactly analogous manner to that of the
higher plants. Here also we have a continuous destruc-
tion of organic materials, usually in the presence of
oxygen, and in that case presenting the character of a
complete combustion. Here also an assimilation of the
new nutrient substances must provide the destructible
material, and at the same time must supply the require-
ments as regards growth and multiplication, and it is a

544 VITAL ACTIONS OF THE LOWER FUNGI.

totally secondary matter that the assimilatory process
in this case runs its course without the aid of a chloro-
phyll apparatus, and that thus certain simple materials,
such as carbonic acid, cannot be utilised as nutrient
Tissue change materials. — As in the case of the higher plants, so also in
funo-i6 ( ^ne lower fungi, a certain amount of energy is set free by

these tissue changes, and this energy is employed for
the functions of these minute organisms, for their pro-
cesses of growth and movement, for the changes in their
tissue, and for the molecular processes.

It is true that by the recognition of these essential
agreements between the tissue change and the develop-
ment of energy in the higher and lower plants the whole
of our insight into the biological processes of the lower
fungi are pretty nearly exhausted. More especially we
can scarcely at the present time form any quantitative
idea as to the relation between the destructive and the
assimilatory tissue change, how far the assimilation and
the formation of new protoplasm is as a rule in excess,
or what amount of the nutrient material is taken up to
serve for the destructive tissue change. Hence in most
matters provisional hypotheses as to the tissue change
and development of energy in the lower fungi must take
the place of facts and certain results.

Differences as There is only one difference between the bacteria and
XrntrherVith tlie higher plants to which we need draw attention,
plants in While the activity of the protoplasm, the Ultra-molecular
nec^ssity°i'or respiration, and the respiration by means of oxygen, with
oxygen. their development of energy and the assimilation of very

various kinds of nutrient materials, are common not
only to the higher plants but also to the fungi, there is a
marked difference with regard to their relation to oxygen.
As has been mentioned, the higher plants cannot be
deprived of oxygen for lengthy periods without injury,
because it is only by means of the process of oxidation
that a sufficient amount of energy is produced; many of
the lower plants, however, can live and multiply for a
long time without the presence of oxygen. In this case
the small amount of energy which is furnished by the intra-
molecular respiration either suffices for the whole of the

ABSORPTION AND ASSIMILATION OF NUTRIMENT. 545

vital functions, and this is the more intelligible the Source of
more correct are our conclusions as to the absolute *

relations of weight and energy in these minute beings ; anaerobes.

or these organisms can take oxygen from certain nutrient

materials and employ it for the oxidation of other com-

plex substances. In the majority of cases the intra-

molecular respiration does not permanently suffice to

supply the necessary amount of energy for the bacteria,

on the contrary they can only bear the loss of oxygen if

a suitable substitute is present in its place. This sub- Substitution

stitute is furnished by the fermentative process, in which the°?imenta-

a large amount of material present in the nutrient medium tive process.

is broken up superficially, but nevertheless in such a

manner that a quantity of energy is set free which is

about equal to that obtained by the process of oxidation.

Thus fermentation may take the place of the oxygen,

and the respiration by means of oxygen and the fermen-

tative activity may be looked on as of equal significance

as regards their relation to the vital processes in the

fungi.

The little that is known as regards this peculiar mode
of tissue change and development of energy in the lower
fungi, may be put together in the following imperfect
description, in which the outlines of the picture which
will ultimately be constructed as the result of future
investigations are probably scarcely recognisable.

2. The Absorption and Assimilation of the Nutrient
Materials by the Lower Fungi.

As the penetration of the nutrient materials must take Absorption of
place in the case of the fungi, just as in that of every
vegetable cell, by means of diosmose through the cell
wall and the plasma, it is evident that only those sub-
stances can be taken up which are diffusible and present
in a watery solution ; where the fungi apparently feed on
solid materials, these substances are previously dissolved
. by the secretions of the organisms. In these preparatory
processes the chemical ferments produced by the fungi
take part ; for example, those which peptonise solid

35

546 VITAL ACTIONS OF THE LOWER FUNGI.

albumen, or which hydrate the saccharine material and
make them available for the use of the fungi, or which
dissolve cellulose, and thus enable those organisms
which live as parasites on vegetables to obtain an
entrance.

The chemical nature of the materials taken up may,
as has been above mentioned, be very various. That
a transformation of these materials, a process of
assimilation, must occur on their entrance into the cells
of the fungi is probable, because it is not at all likely
that these different compounds are of equal value as
regards the different operations which occur within the
cell. It is true that the assimilation of the carbon is
not so marked as in the case of the chlorophyllous
plants, and more especially that carbonic acid cannot be
utilised. Nevertheless methylamine, acetic acid, alcohol,
benzoic acid, tartaric acid, leucine, &c., can without doubt
be converted into more complex substances if they are
offered as the only source of carbon ; and this first product
of assimilation must be built up with a certain expenditure
of energy, which is, it is true, not so great as in the case of
the assimilation of carbon from carbonic acid by green
plants, but which is net replaced by energy obtained from
the sun's rays, but by energy which must be set free as the
result of other transformations occurring in the interior
Assimilation of the cells. For the present we can only form hypotheses
as to the nature of the first carbon assimilation product.
In the case of the higher chlorophyllous plants starch is
frequently one of the first products ; in the case of the
lower fungi, however, this substance is apparently
with few exceptions entirely absent (only in some
species of bacilli and in leptothrix, see page 370). From
the varying nutritive value of the carbon compounds we
may perhaps come to the conclusion with Niigeli that
the first product of assimilation consists of three carbon
atoms, with which hydrogen and oxygen atoms are com-
bined, and which can then unite with a similar complex
of three carbon atoms to form a larger molecule of six
carbon atoms ; the more nearly the nutrient materials
approach this hypothetical body the less are the difficul-

ABSORPTION AND ASSIMILATION OF NUTRIMENT. 547

ties in their assimilation, and the more suitable are
they for the nutrition of the plant.

Without doubt also the nitrogenous bodies are built Assimilation
up to a very large extent in the cells ; and not only °
those which constitute the protoplasm, but also those
which are broken up in the intra-molecular respiration
are probably always of more complex structure than
the nutrient materials. Even the peptones undergo a
transformation during assimilation, and where ammo-
niacal salts and amides are the only sources of nitrogen
a complex process must result, and more especially a
union with assimilation products rich in carbon. The
varying expenditure of energy which is necessary for
building up the assimilation products according as the
material offered as food is closely allied to these products
in composition, or differs much from it and is much
simpler, explains in part the varying nutritive value of
these compounds. The more active the growth and the
new formation of protoplasm, and the more heterogeneous
the nutrient materials, the greater is the amount of
energy which must be set free by the respiratory
processes.

The salts, likewise, do not always appear to be taken Role of the
up from the nutrient mixture in the same form in which Sitricnt
they are present within the cells. Here and there substances..
transformation and decomposition must occur under the
influence of the organic acids which are formed ; further,
sulphur, phosphorus, and magnesium, and possibly also
calcium and potash, enter into combination with the
complex molecules of the proteid materials of the proto-
plasm. For the production of the phosphorus, phosphoric
acid seems to be alone suitable ; the union of the
phosphorus with proteid bodies must occur within the
cell. These transformations of the inorganic materials,
however, are much less extensive, and require much less
energy, than those of the. organic substances.

In the case of the higher plants the composition
of the salts may vary very greatly. Often excessive
quantities of the necessary nutrient salts are taken
up, so that the relation of the individual constituents

548 VITAL ACTIONS OF THE LOWER FUNGI.

to the ashes varies very greatly ; elements are also often
absorbed which do not in reality possess the signifi-
cance of necessary nutrient materials, and they can pass
through the plant or be deposited in various parts of
it without exercising any function (for example silicon,
aluminium, manganese, &c. ; silicic acid may at times
form 50 per cent, of the ashes). It is still uncertain
whether anything similar occurs in the case of the
fungi ; the analyses which have been as yet made are not
sufficiently elaborate to enable us to draw conclusions as
regards this point.

As, according to Na'geli's experiments, potash cannot
be replaced by calcium or magnesium, it is probable that
the alkalies and the alkaline earths play very different
parts ; the latter only appear to form deposits in plasma
and in the cell wall, while the alkaline salts are in part
dissolved in the free cell fluid. That the potash com-
pounds cannot be replaced by sodium or lithium is pro-
bably not due to diosmotic differences, but to the less
affinity of potash for water ; we may perhaps assume
that the salts of sodium and lithium when in a state of
solution are surrounded by firmly united molecules of
water, which render them unsuitable for contact (Nageli).

3. Alterations which the Nutrient Materials undergo,
and the Functional Activity of the Lower Fungi.

Relation be- The materials assimilated undergo within the cell a
' series of transformations, in that they are either employed

materials and jn faQ manner described above for the formation of plastic

the products

of the destruc- material, and thus for building up new cell substance; or

un(lerg0 the destructive tissue change in which they
are destroyed by the respiration, and in part converted
into materials which can no longer serve as nutrient
material, and which must be got rid of as excreta. Just
as in the tissue change of animals, it is not by any means
necessary to assume that all the assimilated materials
form in the first place cell substance and afterwards
undergo destruction; it is, on the contrary, probable that

ALTERATIONS WHICH THE NUTRIMENT UNDERGOES. 549

only a small fraction is employed to replace the cell
substance which has been destroyed, and that the greater
part remains in the juices of the cell, and is subjected to
the decomposing action of the protoplasm while it is in con-
tact with it in a soluble form ; finally, a very varying por-
tion is employed for the formation of new cell material,
and thus meets the demand for growth and multiplication.

A more accurate insight into the quantitative division
of these respective roles is however impossible at the
present time. It is, indeed, frequently doubtful whether
a body which is found by analysis to be a constituent part
of the organism should be looked on as a plastic material
suitable for its future functions, or only as an excretory
product. It sometimes happens that substances which
are split up from more complex compounds by intra-
molecular respiration and excreted by the cells, can still
act as nutrient materials, and can be employed by other —
or it may be the same — cells for the formation of plastic
material ; and in this case it is more or less a matter of
choice whether these bodies are reckoned among the
excreta or among the plastic materials. This difficulty,
however, is present to a much less degree in the lower
fungi than in the higher plants; for in the former we
may look on the gaseous bodies, such as carbonic acid,
with certainty as excreta, whilst the higher plants can
assimilate them again.

As nitrogenous plastic materials, we have chiefly the Nitrogenous
whole group of proteid bodies ; these are present in materials,
solution in the juices of the cell, and then either undergo
decomposition in the protoplasm, forming for example
new cell substance, or are deposited in an insoluble
condition in the cell protoplasm. Nageli was able to
make out the surprising fact that yeast cells excrete
albumen and peptone; the peptone being produced in
non-fermenting neutral or acid nutrient media, and
albumen in fermenting or non-fermenting fluids with an
alkaline reaction. In addition to the proteid substances
numerous amides and amido-acids, especially asparagine
and glutamine, are found in the higher plants. These
may be looked on partly as forerunners, and partly as the

550

VITAL ACTIONS OF THE LOWER FUNGI.

Absence of
nitrogenotis
excrementi-
tious mate-
rials.

products of the decomposition of the proteid materials.
In the same manner amides, such as leucine and tyrosin,
also guanine, xanthine, and sarcine, are found in the yeast
and fission fungi. More especially in the so-called self-
fermentation of the yeast numerous combinations of this
kind occur, while asparagine and glutamine have not as
yet heen demonstrated in "the lower fungi.

These amido bodies are for the most part good nutrient
substances; there is no doubt that in the case of the
lower fungi the necessary nitrogen can be obtained from
them alone, and that they suffice for building up the
proteid material of the protoplasm ; while, on the other
hand, where the nutriment is exclusively albuminous, or
in the self-fermentation of the yeast, it has been shown
that they arise from the splitting up of proteid-like
bodies. These serve at the same time as plastic material
and as excreta ; and it is typical of the economical manner
in which as regards nitrogen the functions of the fungi are
performed, that in the decomposition of these substances
portions as a rule remain, which can again be utilised.

Those nitrogenous substances which readily appear
in a gaseous form, such as trimethylamine and various
compounds of ammonia — e.g., carbonate of ammonia,
sulphate of ammonia, &c. — cannot on that account be
looked on as excreta. These also can, under conditions
otherwise favourable, act as satisfactory nitrogenous
nutrient materials, and it appears not improbable that
they may be again employed as plastic substances.
Accordingly, it is only free nitrogen, nitro bodies, and,
in the case of some classes of fungi, the nitrates, which
can be reckoned as under all circumstances excretory pro-
ducts ; and as these apparently only occur under special
circumstances, there is almost never a separation of
undoubted excrementitious nitrogenous products. Hence
it follows that a colony of fungi may exist and multiply
for an extremely long time on a very small quantity of
nitrogenous material, because the products of the decom-
position of the proteid materials constantly recombine
with non-nitrogenous compounds, and thus form new
proteid substances which may again be utilised.

ALTERATIONS WHICH THE NUTRIMENT UNDERGOES. 551

It has, however, been shown, more especially in the
case of yeast, by the investigations of Pasteur, Schiit-
zenberger, Mayer, and others,* that the amount of
nitrogen gradually diminishes when yeast is cultivated
in a pure saccharine solution ; and this is true not only
as regards the percentage quantity of nitrogen, but also
as regards its absolute amount ; it therefore follows that
nitrogenous materials are separated as excreta, and
disappear in a gaseous form. Such a loss of nitrogen
often occurs, when there is a relatively quick and copious
formation of volatile nitrogenous substances which is not
compensated for by the assimilation of nitrogen by the
cells. Further, if those nutrient materials which can
furnish carbon to the cells are absent, all those nitro-
genous products of decomposition which do not at the"
same time contain utilisable carbon in their molecules
(for example, ammonium salts, urea, oxamide), must
remain as useless excreta; and in such a case, the
diminution of the nitrogenous material is very readily
noticeable, but in reality only because the carbon is not
used up in such a sparing manner, and because the
continuous loss of the carbonaceous gases leads to the
exhaustion of this element. Finally, the amount of
other nitrogenous substances in the nutrient material
exerts an influence; if numerous highly nutritious
nitrogenous bodies are present, nitrogenous molecules of
an excrementitious character will appear much sooner,
and, being less suitable as nutrient materials, will not be
further used up. In cases of necessity, however, part
of the nitrogenous decomposition products may probably
again form nutrient material, and in this way there is a
very parsimonious circulation of the material.

These facts enable us to some extent to under- Peculiar cir-
stand Bolton's experiments, referred to above, in which nitrogenous °
some forms of bacteria can live and multiply rapidly in matenal-
pure distilled water, i.e., where an extremely minute
quantity of nutrient material is present. These experi-

* Pasteur, Ann.Chim.phys.,(3) 58, 507.— Schiitzenberger, Compt.rend.,
1874, vol. 78.— Mayer, (Inters, uber die alkokoL Gahrung: Heidelberg,

552 VITAL ACTIONS OF THE LOWER FUNGI.

ments showed an equally marked multiplication of the
organisms if the growth was allowed in the first place to
attain its maximum, and if the water was then sterilised
and again sown with individuals of the same species of
bacteria; this occurred on several repetitions of the
process. In this case it is evident that the products of
tissue change must have been to a great extent excreted
in a form which could again be utilised, and that the
dead individuals could in like manner serve as nutrient
material. It is only by some supposition of this kind
that we can conceive the continuation of the life of these
fungi with such a slight diminution of the organic
materials, and the repeated development of new genera-
tions on the same substrata.
Non-nitrogen- Non-nitrogenous plastic materials seem to play a
much less important part in the life of the fungi than
in that of the higher plants. Starch is only found in
exceptional cases, and of the other carbo-hydrates we
find, in the case of mould fungi, trehalose and glucose,
and in some cases also the alcohol mannite, which is
usually reckoned among the carbo-hydrates. Of organic
acids, tartaric acid, malic acid, and citric acid are usually
reckoned as plastic materials, but as regards their destiny
in the fungi nothing is as yet known ; fatty oil seems,
however, to be a frequent constituent of the cells of
the fungi. Along with these mobile matters, corre-
sponding in so far to soluble albumen, we have also
cellulose, which is deposited in the cells and constitutes
in the case of the mould and yeast fungi almost the
whole of the cell membrane, but in the fission fungi
only a small portion (see p. 526). — These materials
are taken up from the nutrient substrata only to a
slight extent in a prepared and utilisable form. As a
rule, they arise in two ways, which very probably are
often combined. We either find that they are built up
of more simple compounds, as is, for example, certainly
the case when relatively simple compounds (acetic acid,
alcohol, leucine) are the sole source of carbon, or the
non-nitrogenous plastic materials arise by the splitting
up of more complex molecules, and more especially of

ALTERATIONS WHICH THE NUTRIMENT UNDERGOES. 553

the proteid substances, and this is, in fact, the only
mode of origin when the fungi are fed, for example,
only on peptone or albumen.

We must imagine, then, that the further fate of the
non-nitrogenous substances is that they are in part
employed for building up portions of the organisms
(cellulose, fat) ; in part they combine with the nitro-
genous molecules, and thus furnish the proteid-like
materials ; in part, lastly, they are split up in the
protoplasm, chiefly in the form of carbo-hydrates, and
further destroyed by the oxygen, thus furnishing true
excretory products. Some of them can, like the nitro- Non-nitrogeu-
genous materials, act on the one hand as plastic material, products,
and on the other hand as excreta ; for example, the
organic acids (which are scarcely utilised when better
carbonaceous nutrient materials are present at the same
time) are made use of and given off if the nutrient
material be poor in carbon, but otherwise suitable.
Among the non-nitrogenous constituents of the fungi
there are, however, some which must be looked on as
true excreta, and which always act as such. Thus,
oxalic acid, formic acid, &c., cannot again play a part
as nutritive compounds ; and carbonic acid more espe-
cially cannot be utilised by the fungi, and hence must
in all cases be looked on as excrementitious matter.
As, however, carbonic acid is always produced by all
the fungi, we have in its separation the chief reason
for the gradual impoverishment of a nutrient mixture.
Some aromatic products appear also to be formed
to a slight extent in the tissue change of the fungi ;
for example, phenol, skatol, indol, &c. As a rule,
these bodies are bad nutrient materials, and indeed,
at a certain degree of concentration, can act as
poisons, and hinder the development of the fungi,
even when other nutrient compounds are present ; thus
they for the most part behave as true excretory
products.

Oxygen is the element which, in addition to the Tissue change-
materials mentioned, takes the most active part in the
changes which occur in the bodies of the fungi. As

554 VITAL ACTIONS OF THE LOWER FUNGI,

the result of its action there is at first a complete
combustion, and therewith a production of active energy
which suffices for the functional activity of the organism.
The most various groups of atoms fall a prey to the
oxidising action of the oxygen, nevertheless it is chiefly
those which have been formed in the protoplasm as the
result of the intra-molecular respiration, and which are
more easily attacked by the oxygen than the materials
which are taken up by the food and formed by the
process of assimilation. The absorption of oxygen, and
the respiration by means of oxygen, go hand in hand
with the energy of the decomposition which takes
place in the protoplasm, and therefore with the
activity of assimilation and growth, and thus they
render a large amount of energy available for the active
tissue change. — External influences, especially the pres-
sure of oxygen in the surrounding medium, appeal-
relatively indifferent as compared with the powerful
influence of the protoplasm ; it is only the temperature
of the nutrient materials which seems to exert a more
marked influence on the amount of respiration, but it
acts only by influencing the protoplasm and the decom-
position occurring in it. In the case of the higher
plants, it has been found that as the temperature rises,
the extent of the respiratory process continually increases
in such a manner that its curve rises from zero until
the temperature at which death occurs is almost reached,
and then it suddenly falls to zero . Whether a similar law
holds good in the case of the micro-organisms is not yet
known, but it is, a priori, probable.

Tissue change jf OXVgen js absent, decomposition in the protoplasm
is absent. still continues for some time, as has been ascertained
by investigations on higher plants, and more especially
on fruits, but the tissue change differs both as regards
its products and its energy. Atomic combinations
which would otherwise at once enter into union with
oxygen, either remain unaltered after they are once
formed, or enter into combinations with other bodies, so
that all sorts of products result, which are not observed
when plenty of oxygen is present. Carbonic acid and

ALTERATIONS WHICH THE NUTRIMENT UNDERGOES. 555

water are chiefly formed when , oxygen is present, and
beyond this only slight quantities of compounds which
are not so completely oxidised; where oxygen is ex-
cluded we still find a production of carbonic acid, which
is by no means insignificant in amount, but, nevertheless,
is much less than that produced by the respiratory pro-
cess (282 grammes of pears furnished, for example, in
5 months 1762 ccm. of carbonic acid) ; in addition,
alcohol, organic acids, and at times hydrogen, are
formed.* Only a very minute quantity of energy is set
free by the formation of these products from the more
complex molecules ; so that on the whole it is only for
a short time, and under otherwise favourable circum-
stances, that the requirements of the living cells as
regards energy can be supplied.

Although this intra-molecular respiration, as has been
mentioned above, suffices for the complete supply of the
energy required in the case of the anaerobic fission
fungi, wTe have no facts with regard to the more intimate
processes in these cases, nor with regard to the products
formed. The tissue change of these organisms is more
easily analysed when they can at the same time excite
fermentation in the nutrient materials. In this case
they are under particularly favourable circumstances as
regards life, in that they have a substitute for the supply
of the necessary energy in the absence of oxygen. Under
these circumstances they are able to supplement the
decompositions which take place in their protoplasm in
such a way that a very large quantity of fermentescible
substances — much more than the cells are usually able
to decompose in their interior — is superficially broken
up with the liberation of energy ; and the latter is then
utilised by the living and growing cells to supply the
energy they require. At the same time, the substances
which undergo this decomposition cannot be completely
burned up; on the contrary, relatively complex pro-
ducts result, which differ much according to the fer-

* Lechartier and Bellamy, Compt. rend., 1869, T. 69; 1872, T. 75;
1874, T. 79.— Brefeld, Landicirthschaf. Jahrb., 1876.— Miintz, Ann.
Chim. Phys., 1876.

556 VITAL ACTIONS OF THE LOWEB, FUNGI.

mentescible material, and are in part similar to those
which usually arise when the respiration is exclusively
intra-molecular.

If We attemPfc to estimate quantitatively the tissue
change of the fungi in the manner usually employed in
the case of other organisms, viz., by placing on the one
side the quantity of material taken in, and on the other
side the amount which is destroyed, and also that
employed for building up new tissue, we soon find that
we are not as yet in a position to make any such
estimation. If fungi settle in a nutrient medium the
nutrient materials are consumed very quickly, the fungi
multiply rapidly, and a large portion of the nutrient
materials consumed is contained in the newly formed
colonies of cells which are distinctly visible to the naked
eye. Another portion has, however, been used up in
the respiration and in the destructive tissue change,
volatile products escaping and other excretory sub-
stances being dissolved in the nutrient medium. It
often happens that the elementary constitution of the
latter is completely altered, because the products of
the tissue change have set up changes which destroy
the nutrient qualities of the remainder of the nutrient
solution (formation of excess of acid or of an alkaline
reaction with precipitation of earthy phosphates, &c.).
Hence it is very difficult by analysis of the nutrient
substratum to estimate the relative results of assimila-
tion and of destruction, and we require more numerous
investigations before we can obtain an insight into
the quantitative relations of the tissue change of the
fungi.

If we only pay attention to the process of assimilation,
and if we take into account the enormously rapid multi-
plication of the fungi, we can understand as the result of
this process alone the remarkably rapid consumption of
a nutrient medium (especially where fission fungi are con-
cerned). As above stated, we may assume that the
complete growth and the division of a bacterium into two
organisms occurs on an average within one hour ; a single
bacterium introduced into a nutrient solution furnishes

ALTERATIONS WHICH THE NUTRIMENT UNDERGOES. 557

after 48 hours (where there is no interference with
growth) a colony consisting of two hundred and fifty-
six billions of individuals ; and this colony will, accord-
ing to Nageli's estimation, represent a weight when Estimation of
dry of about eight grammes, which consist chiefly of
albuminoid substances. During the next hour sixteen required,
grammes, and after a second hour thirty-two grammes
of the nutrient solution will be transformed into
fungus tissue ; and in the course of the third day,
more especially where we commence with a number
instead of a single individual, we have truly colossal
numbers which as a matter of fact are only not
usually met with, because the close aggregation of the
fungi and the production of noxious materials as the
result of their growth hinders their free development.

Finally, as regards the interchange of energy, which interchange
accompanies the tissue change of the fungi, we do not as
yet know anything directly, but can only draw conclusions fungi,
from analogies with the higher plants. As regards the
amount of energy taken in, the state of matters in the
lower fungi differs somewhat in that it is practically
only the chemical transformations of which we spoke
above which furnish the necessary energy. In the case
of the higher plants the rays of light supply the energy
necessary for the assimilation of carbon ; but the fungi
which do not contain chlorophyll are unable to utilise
this source of energy, and the whole assimilatory process
takes place at the expense of the energy which has been
liberated by chemical decomposition.

The energy which has been obtained by the respiratory
process is used up partly in the process of assimilation
and partly in the further combinations of the materials ;
also in the process of growth and germination ; in loco-
motion ; and finally in the production of heat and light. —
As regards the consumption of energy in the processes
first referred to, we have no precise knowledge. In the
process of growth, more especially in the case of the
fission fungi, a large quantity of energy is often used up;
rapid growth will therefore always go hand in hand with
free respiration and the production of carbonic acid. A

558

VITAL ACTIONS OF THE LOWER FUNGI.

Influence of

Of oxygen.

Of nutrient
materials.

Of light.

Production of
heat.

considerable expenditure of energy is also necessary for
the process of the germination of spores, and this energy
is only obtained in the case of most of the fission fungi
by the respiration with oxygen, or by a vicarious intense
fermentation. The movements of the fission fungi are
swimming movements in fluid media, and are generally
or always produced by cilia. The mode of movement
varies much (seep. 159), and it is usually associated with
simultaneous rotation around the long axis. The energy
of the movement seems to be dependent especially on the
temperature and on the supply of oxygen.

Too low a temperature, like too great heat, leads to a
condition of arrest of movement, and the intermediate
temperatures which favour movement most, vary very
markedly in the different species of bacteria. Accord-
ing to Engelmann's experiments cited above the tension
of the oxygen also influences the individual species
in very varying degrees, and very slight alterations
in it often interfere with locomotion. — Pfeffer* has
further indicated the presence of suitable soluble nutrient
materials as an exciting cause of movement ; where the
nutrient material is introduced into the fluid containing
the bacteria at one side, the bacteria move towards this
part; and if a capillary glass tube containing nutrient
solution is placed in the fluid, the bacteria move towards
the orifice of the tube and pass into its interior. If the
nutrient materials are inadequate these movements do
not occur. — Whether, finally, light exerts an influence
on the mobility of the fission fungi, in a similar manner
as it does in the case of certain swarming spores, must
remain for the present undecided, because too few species
have as yet been tested in this direction.!

Another form of movement is presented by alterations
of shape in the protoplasm without any true locomotion ;
the dancing movement of the micrococci may be ascribed
to changes of this kind.

A distinctly noticeable production of heat, similar to

* Unters. des botan. Jnstituts zu Tubingen, i., 3 Heft,
f See Strasburger, Wirkung dcs Lichts und der Wiirme auf Schwiirm-
fporen, 1878. — Engelmann, Botan, Zeitg., 1882.

THE PRODUCTS OF THE TISSUE CHANGE. 559

that seen in the higher plants, can also he observed in
the lower fungi. This is minimal in amount if the
intramolecular respiration alone is going on, and if
there is neither access of oxygen nor the occurrence of
fermentation ; under these conditions an elevation of
temperature of *2° C. over the surrounding temperature
was found in yeast (growing in hydrogen) ; when air
was admitted the elevation of temperature increased to
1*2° C., and when fermentation occurred, to 3 '9° 0.*
These numbers, of course, only apply to the particular
circumstances under which they were obtained. Eleva-
tion of the temperature of the nutrient medium has also
been observed in the case of the fission fungi, though
chiefly during the fermentative action. t

Lastly, a development of light sometimes accompanies Development
the vital processes of the fungi. In the case of some of of lightt
the higher fungi, especially of species of Agaricus, this
phenomenon has been known for a long time; quite
recently the phosphorescence which putrefying fish or
pieces of flesh at times show has been ascribed to lower
fungi, especially to micrococci, which, however, only
occasion this phenomenon when a free access of oxygen
and a temperature not too low, permit an energetic
respiration.

4. The Products of the Tissue Change of ilie Lower
Fungi.

The number of the products of tissue change which Products of
are from time to time observed in cultivations of fungi il
is extremely great ; gases, such as carbonic acid, hydro-
gen, marsh gas, sulphuretted hydrogen, ammonia ;
nitrates ; water ; sulphur ; also volatile bodies, such as
trimethylamine, alcohol, formic acid, acetic acid, pro-
pionic acid, butyric acid ; fixed acids, such as lactic
acid, malic acid, succinic acid, oxalic acid, tartaric acid;
sulpho- acids, such as taurin, amides of the fatty acids,
especially leucine, alanine, &c. ; bodies of the aromatic

* Eriksson, Unters. b. dem botan. Institut. in Tubingen, 1881, Heft 1.
t Popoff, Botan. Jahresb., 1875. — Wernich, Organisirte Krankheitsgifte.

560 VITAL ACTIONS OF THE LOWER FUNGI.

series, such as tyrosine, phenol, cresol ; reduction pro-
ducts, such as indol, hydro-paracumaric acid ; complex
molecules, such as carbo-hydrates, peptone, hydrolytic
ferments ; finally, colouring materials and alkaloid-like
poisonous substances. According to the species of the
chief fungus present, and according to the external con-
ditions of the nutrient medium, sometimes the one,
sometimes the other of these products appear, and a
particularly large number of them is observed when we
have to do with fermenting or putrefying substrata.

Among these products of tissue change we can sepa-
rate a group which generally occurs in the vital processes
of all, or at any rate of numerous fungi ; and we can place
in opposition to this the group of the rarer and more
specific products, the occurrence of which is limited to
one or a few species. It is also of special interest to
ascertain in how far the number and the quality of the
products of each individual species of fungus undergo
variations according to differences in the composition of
the nutrient substratum, and whether, on the other
hand, when the nutrient substratum is the same, the
same products are always furnished by the same species
of bacteria ; in other words, whether the power of each
species of breaking up a given nutrient substratum in a
particular manner is constant and special. It is clear
that the answer to these questions is of extreme
significance for the diagnostic value of the products of
the tissue change.

Carbonic acid. Carbonic acid alone is of constant occurrence ; water
and a nitrogenous body also undoubtedly always appear
as products of decomposition, but they do not, like the
carbonic acid, come under observation as excreta. The
life of the lower fungi seems never to go on without
separation of carbonic acid ; hence it is always present,
although in very varying quantities, whether it arises
only as the result of intra-molecular respiration, or
whether oxygen has been present, or fermentation has
occurred.

Fatty acids A production of fatty acids and oxy- acids (acetic acid,
propionic acid, butyric acid, lactic acid, succinic acid,

THE PRODUCTS OF THE TISSUE CHANGE. 561

&c.), as well as of their amide compounds, occurs very
often. We find one or other, or it may be a mixture of
them, in most of the cultivations of fission fungi even
when there has been no fermentation, but merely simple
•consumption of the nutrient material and the multipli-
cation of the fungi ; they are present, however, in much
larger quantities when fermentation has occurred.

More seldom, but perhaps also equally widely distri- Aromatic
buted, we find aromatic bodies (phenol, paracresol, &c.) prod
AS products of the tissue change of the fission fungi ;
these have as yet been found chiefly or only in ferment-
ing and putrefying mixtures.

Further, numerous fission fungi produce ferments, ptomaine?,
others produce substances which act like poisons and £erments-
resemble alkaloids, and are commonly grouped together
under the term ptomaines. These two products of
tissue change require, on account of their special im-
portance in hygiene, a special discussion in the follow-
ing pages.

Colouring materials are in some cases very common, Colouring
in others they are among the rarer products of the m
tissue change. Red pigment is, for example, formed by
the pink yeast, by micrococcus cinnabareus, by bacillus
prodigiosus, by bacillus indicus ; green colouring matter
by bacillus pyocyaneus, bacillus fluorescens putidus,
bacillus erythrosporus, bacillus fluorescens liquefac.,
•&c. ; blue colouring matter by bacillus cyanogenus, and
in putrefying mixtures (Brieger, Rohmann) ; violet by
bacillus janthinus ; brown by bacillus fuscus ; yellow by
very numerous micrococci and bacilli. — These pigments
are very rarely present in the cells or in the cell walls,
(these are usually colourless), and it is only the sub-
stratum on which the fungi grow that is impregnated
with the pigment. It has been further observed,
and has recently been ascertained by Liborius in the
•case of a large number of pigment bacteria, that the
•colouring matters are only formed when free access
of air is allowed, while if the access of air is even only
moderately hindered (by covering with oil, &c.), the sub-
strata and the colonies remain completely colourless,

36

562

VITAL ACTIONS OF THE LOWER FUNGI.

Dependence
of the forma-
tion of the

although otherwise the growth of the fungi is not
affected. Hence the probability is that these pigments
are not produced as such by the fungi, but that the latter
colouring form a chromogenic substance which becomes converted

matters on the

entrance of into the colouring matter only as the result of the action
Influence of of °xjgen. Not uncommonly we notice different shades
tht 1iut?ent of the pigment, and at times even marked differences in

substratum .

on the forma- the colour when the organisms are grown on different
nutrient substrata ; this is evidently due to the influence

pigment.

Chemical
nature of the
pigments.

Products of
fermentation

of the different substrata, and of their reaction on the
chromogenic substance. Such variations in the pigment
are well seen in connection with the bacilli of blue milk.
Very often a difference in the colour of a cultivation is
due to contamination with other fungi ; and this point
must always be carefully tested before we refer the
difference to the influence of the nutrient substratum.

But little has been ascertained as to the precise nature
of these pigments ; with regard to most of them we only
know a few reactions which have already been referred
to in the systematic part of this work. The colouring
matter, which has been most completely investigated, is
that of greenish blue pus, pyocyanine ; Gessard ascer-
tained that chemically this substance was a base which
was closely related to the ptomaines ; the sulphate
and chloride salts crystallise in the form of reddish
needles, a crystalline precipitate is also deposited
from their solutions by chloride of gold, chloride
of platinum, iodide of potash, and mercury, further
by tannin, chloride of mercury, and phosphoric molybdic
acid. From a mixture of ferro-cyanide of potash
and chloride of iron pyocyanine gradually throws down
a precipitate of Berlin blue, but more slowly than
morphine.

We have further to consider the specific products of
fermentation which are limited to certain bacteria.
Many of these, such as lactic acid, butyric acid, nsthylic
alcohol, &c., occur, it is true, very frequently as products
of tissue change and of fermentation, but nevertheless,
when we take into account the quantity of these products
and their relation to each other, we must look on them

THE PRODUCTS OF THE TISSUE CHANGE. 563

as specific products of the action of certain species of
bacteria ; they are only formed in large quantities under
the influence of a few fungi, and they then go hand in
hand with the best development and growth of these
species. It is more seldom that we meet with other
alcohols containing more carbon, such as mannite, vis-
cose, &c. ; these appear almost entirely to be specific
fermentative products of a few species of fission fungi. —
In like manner we have, as rare and limited products of
the tissue change of the bacteria, the granulose of the
fungi, which become blue on the addition of iodine, and
the sulphur of the species of beggiatoa.

These various products of tissue change are not, how- Variations in
ever, so limited to the species of fungi which produces oAfisne*
them that each species only produce one of the products ^^Tof * the
belonging to the same group ; on the contrary, we very alterations in
frequently observe that the same species of bacteria can
at the same time produce carbonic acid, fatty acids,
ferments, ptomaines, and colouring matters ; that they
can also excite fermentation, and eventually can, as the
result of their parasitic growth, set up disease in animals
or vegetables attacked by them. We have already, on
page 351, referred to this matter in the case of many
fission fungi.

As regards the answer to the questions as to the
constancy and specific nature of the products of the
tissue change, it becomes clear from numerous observa-
tions that the individual species of bacteria cannot on
every nutrient soil furnish all the materials which it is
capable of producing, but that, on the contrary, many
products require the presence of special constituents in
the substratum, these constituents not, however, being
necessary for the life of the fungus.

The variation in the shades of the pigment according
to the nutrient substratum points to some such influence
of external conditions ; and this influence is still more
marked, for example, in the case of the bacilli of
glanders and cholera, which only produce a brown
colouring matter on potatoes and not on any of the
other ordinary nutrient substrata ; and it is also shown

564 VITAL ACTIONS OF THE LOWER FUNGI.

by the fact that the occurrence of definite products of
fermentation is absolutely dependent on the presence of
definite fermentescible substances, without which, how-
ever, the life of the bacteria in question can go on very
well. We have also to bear in mind the marked influence
exerted by the presence or absence of oxygen on the
nature of the materials formed ; further, that the com-
position of the nutrient medium and the excess of nitro-
genous or non-nitrogenous substances determine the
relative quantity in which the various products usually
appear. Finally, in some cases abnormal alterations in or
mere accidental admixtures with the nutrient medium
lead to the transitory appearance of unusual products.
In the same way we can observe in the higher plants
the formation of large quantities of amides when there
is no assimilation of carbon ; further, the formation of
benzoic acid when hippuric acid is given to the plants
as the nitrogenous nutrient material. In like manner,
the mould fungi, for example, are able to form gallic
acid and glucose from tannic acid, and it is probable
that the above-mentioned (p. 528) splitting up of the
nitrates occurs in the same way. More elaborate
researches will, without doubt, lead to the discovery of
many of these more or less accidental products of tissue
change occasioned only by deviations in the nutrient
medium, and -disappearing again with alteration in the
nature of the soil.
Constancy of These differences in the excreta do not in the least

the products . . . .

of the tissue prevent us from utilising certain characteristic products
theSrient6 °^ tissue change as a means of recognising the different

conditions species of bacteria. For so long as the external con-
remain the * '. . . T

.same. ditions remain the same, the same products of tissue

change constantly accompany the specific form. We
do not find that other fungi suddenly acquire the power
of yielding products which are characteristic of a certain
species of bacteria ; and where normal conditions are to
some extent maintained, it happens just as seldom that
this species of bacteria loses its characteristic properties,
and furnishes other products of tissue change instead.
Thus we find that the production of colouring matter,

THE PRODUCTS OF THE TISSUE CHANGE. 565

the formation of peptonising ferments, or the specific
fermentations, so constantly accompany the same species
of organism that we can employ these facts as diag-
nostic means for distinguishing and recognising the
species. In the diagnostic key given above the possi-
bility of peptonising gelatine and the production of
pigment form a basis for the differentiation of bacteria
otherwise very difficult to distinguish from each other.

Even when, under the influence of abnormal external
conditions, these characteristic products, and along with
them the most important means of recognising the
species of bacterium, have disappeared, the property of
the fungus in question can still be always regained as
soon as it is cultivated under those conditions under
which this property is usually observed. For even when Eetention of
the temporary unfavourable conditions were so abnormal evS^after the

that some of the individuals died, or were pathologi- action of hurt-
. .„ .,..,, fnl influences.

cally altered, it usually happens that if any individuals

retain their power of development, the same products of
tissue change which are normally observed constantly
reappear under the same normal conditions. The
bacteria evidently behave in this respect as a whole like
the higher plants, which do not acquire or lose the
power of producing this or that specific product of
tissue change ; the hemlock, indeed, loses its power of
producing conium, and the plants which furnish indigo
cease to prepare indigo, when they lead a morbid exis-
tence under abnormal conditions, but both these func-
tions are resumed when more favourable conditions
permit the surviving examples or their offspring to
exercise fully their vital functions, and thus under all
circumstances this power remains as a specific property
of each specific species. — It is only with regard to some With regard
of the properties of the lower fungi, viz., the production tfon^f fermen-
of fermentation or disease, that there is a peculiar tation and
deviation from the behaviour of the higher plants ; the
fission fungi may permanently lose these properties
under the action of abnormal external conditions, and
this loss may then be transmitted to the offspring
through a number of generations even when the con-

566 VITAL ACTIONS OF THE LOWER FUNGI.

ditions of existence have again become normal. This
matter of attenuation is more fully entered into in the
following chapter on the conditions affecting the death
of the organisms.

injury of the The products of the tissue change of many of the

bacteria by fl . £ . 6 . , , . \ ., .

the products nssion fungi appear to exercise a remarkable inhibitory
t/ssuTchange. acti°n on tne growth and multiplication of the same
organisms. This has been definitely ascertained in the
case of certain fermentations; thus, as is well known, in
the alcoholic fermentation, alcohol when present in
the nutrient substratum in the proportion of 14 per
cent, interferes with the vital activity of the yeast
cells ; similarly, the ammoniacal fermentation of urine
ceases when the amount of carbonate of ammonium
in fermenting has risen to about 13 per cent.; in like manner the
lactic acid and the butyric acid, which are formed in
the corresponding fermentations, must be neutralised
by the addition of carbonate of lime or of oxide of zinc,
because otherwise the constantly increasing amount of
free acid is injurious to the life and the fermentative
activity of the bacilli which are at work (lactic acid is in-
In growths jurious even in the amount of 0*8 per cent.). — Analogous
fermentation, actions have also been often suspected with regard to the
products of the tissue change of many bacteria where no
fermentation is going on, but in these instances it has
not been demonstrated with complete certainty. The
relatively rapid death of these bacteria in nutrient sub-
strata which still contain a large amount of good nutrient
materials is usually explained by the hurtful action of
the accumulated products of their own tissue change.
Suppositions have also been frequently made as to the
more precise nature of the materials which come into
play in this action ; attention has been chiefly paid to
the aromatic products (phenol, paracresol, &c.), which
are found in numerous putrefactive processes, for these
as a matter of fact exert an energetic inhibitory action
Nature of the even in very small quantities. But even for these views
products. proof is still wanting, because from the occurrence of

THE PTOMAINES. 567

aromatic substances in certain fermentations we cannot
without further evidence draw conclusions as to their
general presence in the tissue change of other fungi, and
because perhaps in this direction also the individual
species of bacteria have a different and specific behaviour.
— Buchner thinks that he has recently observed a totally
different influence of the products of tissue change in
the case of the cholera spirilla ; these organisms are
thought to develop particularly well, and better than
other forms of fission fungi, in a nutrient solution which
contains the products of the cholera spirilla obtained
from a previous cholera cultivation.*

A further effect of the products of tissue change is injurious
their supposed action on the development of other
species of fission fungi. The observation that some
species, more especially the sensitive pathogenic forms, other bacteria.
rapidly die, when, at the same time, saprophytic
fungi have established themselves in the same nutrient
medium — death occurring much too quickly for any
hurtful action by the withdrawal of nutrient material —
can scarcely be explained otherwise than by supposing
that the products of the tissue change of the saprophytic
fungi have exerted a poisonous action on the other organ-
isms. Here, however, we also require more precise
facts, and more especially with regard to whether the
group of aromatic products which is common to many
saprophytic fungi is the important one, or whether
in the case of different fungi different products take part
in the action against the concurrent organisms.

5. The Ptomaines.

In investigating putrefying mixtures the discovery Ptomaine?,
was first made that, under the influence of bacteria,
nitrogenous bases arise which are, in many respects,
similar to the vegetable alkaloids ; some of these bodies
are innocuous to the higher organisms, others, however,
like the alkaloids, exert a poisonous action. These basic
bodies were found when putrefaction had gone on for some

* Munch, arztl Intell. BL, 1835, Nr. 50.

568

VITAL ACTIONS OF THE LOWER FUNGI.

Extension of
the term
ptomaines to
all the nitro-
genous bases
produced by
bacteria.

First demon-
stration of
toxic putre-
factive pro-
ducts.

First demon-
stration of
chemically
pure
ptomaines.

time in human dead bodies, and the whole group of these
materials was consequently included by Selmi under the
designation "cadaveric alkaloids or ptomaines" (from the
Greek word Trrco^a, a dead body). It is well to retain
this term still, although recent investigations have
shown that nitrogenous bases with specific action
appear not only in the putrefactive process but also
among the products of tissue change of pathogenic
bacteria.

It would lead us too far to give here an accurate
historical statement of the investigations which have
been devoted during the last few years to the demonstra-
tion and analysis of the ptomaines.* The credit of
having first drawn attention to the occurrence of poison-
ous putrefactive bases belongs to Panum ; at a subse-
quent period Bergmann and Schmiedeberg, Zuelzer and
Sonnenschein, Hager, Otto, Selmi, &c., obtained from
putrefying substrata poisonous extracts, which usually
resembled conium in their poisonous action or in their
chemical reactions, but at times also atropine, curare r
delphinine, or morphine. None of these investigations,.
however, led to the isolation of definite chemical sub-
stances from the toxic extracts.

Nencki t was the first to succeed in separating and in.
ascertaining the elementary composition and the con-
stitution of a putrefactive alkaloid. He obtained from,
putrefying gelatine a cry stalli sable body which had
the composition C8HnN, and perhaps the structure-

_NTT This base is isomeric with collidine,.

but differs from it by its behaviour on heating, £c-
Gautier and Etard, at a later period, isolated from
putrefying fish two substances, of which the one appears
to be identical with that obtained by Nencki, while the
other had the composition C9H13N ; further, Guareschi.

* See Husemann's Eeports in Arch. f. Pharmacie, 3 R., Bd. 16—22 ;.
Otto, Anleitung zur Ausmi1tlur,g der Gifle, 6 Aufl. Braunschweig, 1885.—
Brieger, Ueber Ptomaine, Berlin, 1885, und Weltere Untersuchungen iiber-
Ptomaine, Berlin, 1885. See the rest of the literature there, and in.
Maly's Jakresber. f. Thierchvnie.

t Nencki, Ueber die Zersetzung der Gelatine und des Eitmisses, Bern,
1876

THE PTOMAINES. 569

and Mosso obtained, from putrefying fibrine, an oil of
the composition C10HL,N, which has a similar action to
curare ; and E. and H. Salkowski obtained by the
putrefaction of flesh and fibrine a cry stall i sable base,
which on analysis seemed to differ a little in its compo-
sition, C5HUN02 or C7H15N02, and hence probably was
not quite pure.

Brieger has, during the last few years, taken up the Brioger's
study of the ptomaines with great success ; to his in-
vestigations we already owe a number of very important
results.

Brieger isolated numerous nitrogenous bases, partly 1. Putrefac-
from putrefying fibrine, meat, fish, cheese, gelatine, and ptomaines.
yeast ; partly from putrefying human bodies ; and partly
from pure cultivations of pathogenic fungi ; some of
these proved to be non-poisonous, others were distinctly
poisonous.

To the non-poisonous, or, at any rate, to bases which
only act in a poisonous manner in large doses, belong :

1. Neuridine, very widely distributed ; obtained from Non-poison-
the putrefaction of meat, cheese, gelatine (in very large °l
quantities), and from decomposing human organs from

the third day onwards. Composition, C5H14N2, a
diamine which breaks up into dimethylamine and
tri-methylamine. Characterised by the formation of
a compound with picric acid, which is not readily
soluble.

2. Gadinine, obtained from putrefying torsk, has the
formula C7H17N02 ; constitution still unknown.

3. Cadaverine, from decomposing bodies, found in
traces from the fourth day upwards, plentifully from
the tenth to the twelfth days. C5H16N2; has a disagree-
able odour, recalling that of conium.

4. Putrescine occurs along with the former, C4H]2N2.

5. Saprine, likewise a cadaveric alkaloid ; it has the
same percentage composition as cadaverine, but it is
distinguished from it by the characters of its compound
with hydrochloric acid, and of its gold salt.

6. Brieger also found cholin during the first few
days of the putrefaction of dead bodies, and after the

570

VITAL ACTIONS OF THE LOWER FUNGI.

Poisonous
Peptotoxine.

Neurin.

disappearance of the cholin, trimethylamine, also di-
methylamine and triaethylamine.

The formula of cholin is, C5H15N02, and it must be
looked on as trimethyloxaethylammonium oxyhydrate
(CH3)3, N, OH, C2H4, PH. It occurs very widely
distributed in the body, united in lecithin with di-
stearylglycerinephosphoric acid, and appears at the com-
mencement of the putrefaction of dead bodies, probably
by the splitting up of lecithine. Cholin only acts in a
poisonous manner in very large doses.

To the poisonous bases belong :

1. Peptotoxine, the poisonous constituent of many
peptones ; it is formed, for example, in the digestion of
fibrine by artificial gastric juice. It can be in part ex-
tracted from peptone by sethyl- and amyl-alcohol ; com-
position as yet unknown. Frogs and rabbits are killed
with symptoms of paralysis and insensibility. — This
first poisonous product of the splitting up of albu-
minous bodies can probably be also obtained as the
result of the peptonising action of bacteria, although
this has not yet been directly proved.

2. Neurin, obtained from flesh which had putrefied
for five or six days, was formerly frequently confused
with cholin, but is distinguished from it by the absence
of one molecule of water. It has the composition
C5H13NO, and must be looked upon as the oxihydrate
of trimethylvinylammonium (CH3)3, CoH3, N, OH (the

CH2 A
vinyl group = || - Neurin is poisonous in small

CE-/

doses to frogs and mammals ; for cats five milligrams
per kilo-weight is the poisonous dose. The symptoms
observed are, salivation, dyspnoea, in the first place
quickening, then lowering, of the heart's action ; also
violent peristalsis of the intestine, with diarrhoea ; finally,
convulsions and collapse. The group of symptoms
most resembles those produced by muscarine; atropine
appears to be the most active antidote.

Neurin is probably formed from the cholin of the
lecithin by the withdrawal of water, and this separation

THE PTOMAINES. 571

of water seems to occur under the influence of many
putrefactive bacteria. It is possible that it occurs also
under many other circumstances, and especially as the
result of the action of chemical agents.

8. A base similar to, and isomeric with, sethylen-
diamine, of the formula C2H4 (NH2)2. It has been
recently shown to be distinct from aethylendiamine ;
obtained in the putrefaction of fish.

4. Muscarin, long known as the poison of the fungus
of flies (muscardine), an oxidation product of cholin ;
C5H15N03; was likewise found by Brieger in putre-
fying fish.

5. In the putrefaction of human bodies Brieger
obtained, after seven days, the first traces of toxic bases,
and they were got more plentifully after two to three
weeks. Two ptomaines could be recognised, of which,
however, the quantities obtained did not suffice for more
accurate analysis. One of them set up marked diarrhoea
in rabbits ; the other, called mydalein, caused in the
first place dilatation of the pupils, injection of the
vessels of the ear, elevation of the temperature of the body,
marked flow of saliva and diarrhoea, and finally death,
with panting respiration and depression of temperature.

From pure cultivations of specific pathogenic bacteria 2. Ptomaines
Brieger was able to isolate the following bases :— cuiSrations

The bacilli of typhoid fever, when grown in meat in- of pat
fusion, gave rise to no putrefaction, no development of From typhoid
sulphuretted hydrogen, indol, or phenol ; on repeated
occasions, however, a new ptomaine was obtained from
these cultivations, the gold salt of which was most
easily purified; but a more exact analysis of this sub-
stance has not yet been published. This ptomaine
caused, in guinea-pigs, flow of saliva, frequent respira-
tion, dilatation of the pupils, and diarrhoea. On post-
mortem examination the heart was found in a state of
systolic contraction.

Cultivations of Staphylococcus aureus in meat in- From
fusion which was kept at a temperature of 30° to 50° C. staPhylo<
for about four weeks, gave a non-poisonous base which
did not enter into combination with chloride of gold,

572

VITAL ACTIONS OF THE LOWEK FUNGI,

Production of
ptomaines by
cholera
spirilla.

By other
bacilli.

Absence of
ptomaines in
anthrax cul-
tivations.

but formed, with chloride of platinum, a crystalline
compound which could be analysed. More accurate
details are still wanting with regard to this base.

The toxic action of pure cultivations has further been
observed in various kinds of bacteria, without any
attempt having been made to isolate the poisonous sub-
stances. For example, in the case of the spirilla of
Asiatic cholera (see page 440) ; further, in a whole group
of bacilli which cause a similar toxic effect with special
involvement of the intestine, such as bacillus crassus
sputigenus, bacillus oxytocus perniciosus, &c. (see
page 331). Other pathogenic bacteria have been in-
vestigated for similar products of tissue change, but as
yet with negative results; thus, Nencki has in vain
examined cultivations of anthrax bacilli for nitrogenous
bases, and Marme has arrived at the same result with
cultivations of anthrax bacilli made in the author's
laboratory.

Hygienic

The facts which have as yet been made out with
regard to the occurrence of ptomaines are evidently of
very great importance. In the first place, they are of
importance in medical jurisprudence, for medical jurists
must, in investigating cases of poisoning, proceed in a
totally new direction, and with the most extreme care.
Hygiene also has an interest not less intense in the
accurate investigation of these peculiar products of
the tissue change of bacteria. It appears that the
wholesale poisoning of people so often observed, and
which resembles severe epidemics of contagious dis-
eases in its mode of appearance, is commonly caused
by decomposing nutrient materials in the early stage
Poisoning by of putrefaction. In cheese, sausages, meat, or fish,
ing1 ptomaine's t° which these cases of poisoning are usually referred,
fae bases described above, or others as yet unknown,

t/

have probably been formed under the action of bacteria
from the albumen of the nutrient materials in question,
and have occasioned these toxic symptoms. A circum-
stance which favours the occurrence of these accidents,

(cheese, fish,
meat.

THE PTOMAINES. 573

the bases occur in the commencing stage of putrefac-
tion, before any disagreeable smell is noticeable (only
in the slow putrefaction of human tissues was Brieger
unable to discover any poisonous ptomaines during the
first few days), and that, on the other hand, a more
advanced stage of putrefaction seems to destroy them ;
at any rate, Brieger failed to find, on the eighth day
of the putrefaction of meat, bases which were present at
an earlier period.*

The ptomaines also play an important part in certain The ptomaines

.„,.,. , -n i , • as a cause of

infective diseases of wounds. For a long time surgeons putrid
have held the view that " putrid intoxication " arises as intoxication-
the result of the growth of certain saprophytic fungi on
the surfaces of wounds ; these form ptomaines, which are
absorbed and then set up their poisonous action in the
body. Similar phenomena occur, in all probability,
on the wounded surface of the puerperal uterus as the
result of the growth of saprophytic fungi. Further,
intoxication can also occur from the intestine, where it
is not uncommon to find putrefaction of the intestinal
contents and production of poisonous bases; here, how-
ever, absorption is on the whole slower, and occurs in
smaller doses, so that the intoxication is not so intense.
It is also of importance for the production of these
ptomaine actions that the formation of the poisonous
bases may begin in a very early stage of the decomposition
of albumen by bacteria, even before true putrefaction.

Further, the discovery of specific ptomaines in the Specific

,,. ,. . ,. . _ \ .a .! . ,, pbomamesas

cultivations 01 pathogenic iungi evidently gives us the the active
key to the mode of action of these bacteria in the human choiera°l mT
body; we have every reason for believing that the most typhoid
important morbid symptoms of typhoid fever, cholera,
and many other infective diseases are due to the produc-

* In a case of poisoning with mussels, which recently occurred in
Wilhelmshafen, Brieger's investigations have shown (Deutsche med.
Woch., 1885, No. 53) that ptomaines, and, among them, a poisonous
base which has been already analysed (C6H15NO2) and called mytilo-
toxin, were the cause of the disease. The mussels were not in a putrid
condition, but even in the fresh state exerted their poisonous action.
In this case, therefore, there must have been either a production of
ptomaines by the mussels themselves, or else they must have taken up
from the surrounding water poisons produced by bacteria.

574 VITAL ACTIONS OF THE LOWER FUNGI.

tion of specific poisons by the bacteria which are the
cause of the disease, and as the result of this knowledge,
we may entertain the hope that important indications for
a rational treatment of these diseases may result from
the discovery of the specific ptomaines.

A number of important questions with regard to this
matter still require solution. Thus it would evidently be
of great importance to learn whether the putrefactive
alkaloids are formed in the same quantity and with the
same poisonous qualities by different bacteria in the
same material, and conversely by the same bacteria but
under varying composition of the putrefying material and
influence of under varying external conditions. As regards the latter
materials on point, a larger amount of lecithin and cholin may, for
of6 tomaines1 examP^e? favour the formation of the poisonous neurin ;
and as regards the various species of bacteria which set
up putrefaction, researches, which are as yet incomplete,
but which are being carried out in the author's laboratory
by Henrigan, have already shown that certain anaerobes
can, in the course of putrefaction without the presence
of oxygen, furnish poisonous products much more quickly
and energetically than any of the other putrefactive
fungi which have been as yet tested.

Varying re- It seems in fact as if, as in the case of the higher

sapropnytic6 fungi> the production of poisonous substances by different

bacteria to the kin(Jg of bacteria can show very marked qualitative and

ptomaines. quantitative differences, so that an early and detailed

knowledge of their vital actions is the more desirable in

the case of the individual species of bacteria.

6. Chemical Ferments.

Ferments. jjy "ferments" or "enzymes "we understand corn-

Definition. J ••«-*•••

plex organic materials which readily undergo alteration,

and have the power, within certain limits of tempera-
ture, of transforming relatively large quantities of other
organic materials in such a way that bodies arise with,
on the whole, less heat-producing power than the mate-
rials from which they were formed.

CHEMICAL FERMENTS. 575

Such ferments play an important role in physiological
processes, especially in the nutrition of the body.
Stated generally, they have the power of so transforming
materials which, as such, cannot enter an organism, nor
perform any function in it, that they become soluble,
diffusible, and capable of being utilised as nutrient
substances. Insoluble albumen is converted into peptone ; Importance
starch and cellulose into soluble dextrose ; fat is broken cesses^rf10"
up; cane-sugar, which cannot be decomposed in proto- nutrition-
plasm, is converted into glucose, which is readily acted
on. The most highly organised animals require these
ferments just as much as the most lowly organisms; the
former prepare them in special glandular organs, but
even in the lower fungi, in which no organs can be
distinguished, ferments are nevertheless a very common
product of tissue change, and one necessary for nutri-
tion.

As regards the mode of action of these ferments, the
most striking point is that a relatively small quantity
suffices to transform a large quantity of the body which
is being broken up ; the whole chemical action, therefore,
seems to run its course without the ferment itself playing
an active part or becoming altered. This circumstance
led to the use of the term " ferment," as applied to the
chemical bodies of which we are speaking, and to the
inclusion of the processes set up by them in the same
class with the fermentative and putrefactive processes.
Indeed, many investigators look on it as probable that
all the fermentative processes may be referred to such
chemical ferments, and believe that it is only by such a
view that it is possible to understand aright the processes
of fermentation.

Nevertheless the investigations which have been made
as yet, compel us to take the view that the true fer-
mentations, and the action of isolated chemical ferments,
differ so much from each other that they must both be
treated separately. As a rule, however, the chemical
ferments play a part, and, in fact, set agoing many
complex fermentative and putrefactive changes; and
they play an important rdle in the nourishment of many

576

VITAL ACTIONS OF THE LOWER FUNGI.

Diastatic
ferments.

of the exciting agents of fermentation. For these
reasons the chemical ferments require to be considered
more in detail in this place.

We distinguish the following kinds of chemical fer-
ments : —

1. Diastatic ferments. These convert starch into
forms of glucose (maltose, dextrose, &c.), and, as a rule,
they only act where the reaction is neutral or slightly
acid, but not where it is alkaline. They occur fre-
quently in animals and plants. Of animal ferments we
have, belonging to this group, the ptyalin of the saliva ;
the ferment of the pancreatic juice, which, when the
reaction is alkaline, converts starch into glucose ; the
ferment contained in the liver, which acts on glyocogen ;
two ferments present in the urine (Selmi,* Bechamp
and Baltusf), &c. We find the diastatic ferments very
widely distributed in plants ; they occur in specially
large quantities in germinating wheat, in malt, and also
in the most various organs of plants, in young seeds,
leaves, &c. (BrasseJ).

Diastatic ferment has been frequently demonstrated
change of the during the last few years as a product of the tissue
change of bacteria. Marcano§ found a ferment of this
kind in bacteria which frequently occur in the external
sheath of maize ; Hueppe || demonstrated a diastatic
action in connection with the bacterium lactis ; Miller ^f
isolated a species of bacteria from human intestinal
contents which was able to dissolve starch. Wortmann**
was also able to demonstrate energetic diastatic action
in a mixture of bacteria which he obtained from decom-
posing beans or potatoes, and which he cultivated in a
mixture of nutrient salts and wheat starch. — That the
solution of the starch in these cases really depends on
the production of a ferment can, however, only be re-

* Selmi, Atti del Lincei, vol. v.

t Bechamp und Baltus, Compt. rend., vol. 92.

X Brasse, Ibid., vol. 99.

§ Marcano, Ibid., vol. 95.

|| Hueppe, Mitth. a. d. Kais. Ges. A., vol. ii.

f Miller, Devtsch. med. Woch., 1885, Nr. 49.

** Wortmann, Z.f.physioL Chem., vol. vi.

As products
of the tissue

CHEMICAL FERMENTS. 577

garded as proved when we have succeeded in separating
the active ferment from the hacteria. As a matter of isolation of
fact, the experiments which have heen made in this th
direction by Marcano and by Wortmann, have led to
an imperfect isolation of the ferment ; the former found
that the cultivating fluid filtered through porcelain, or
treated with chloroform, still showed a diastatic action ;
and Wortmann was able to demonstrate an isolated fer-
ment by extraction of the mixture of bacteria and pre-
cipitation with alcohol; this ferment was soluble in
water, converted starch energetically into glucose, acted
better in faintly acid solutions, and also exerted its
diastatic action when oxygen was excluded. Wortmann
found that this ferment was only produced by the
bacteria in question when they had at their command
neither albumen nor any other source of carbon ;
usually they furnished a peptonising ferment, but
instead of this they produced a diastatic ferment when
they were in a starving condition, and were unable to
obtain the necessary nutriment in any other way than
by solution of starch ; further, the ferment was only
formed when the bacteria had plenty of oxygen. — Wort-
mann's observations are, however, not completely con-
vincing, because he worked with an unknown mixture of
bacteria, and also because the possible action of the
living bacteria, in addition to that of the supposed
isolated ferment, is not entirely excluded in the re-
searches, especially as the activity of the solution of the
ferment only appeared after a longish incubation period.
Nevertheless, taking into consideration all these experi-
ments, it is very probable that renewed experiments free
from these objections will lead to similar results as re-
gards the diastatic ferments of bacteria.

2. Inverting ferments. These convert cane-sugar, invertin.
milk-sugar, and maltose into forms of glucose (dextrose,
laevulose, galactose). They occur in the digestive track
of animals, but they have not yet been demonstrated in
the higher plants. A similar ferment has, however,
been demonstrated by Gayon* in species of penicil-

* Gayon, Bull. soc. ckim., 35, 58.

37

578

VITAL ACTIONS OF THE LOWER FUNGI.

bacteria,.

Hum and aspergillus (not in mucor); and Bourquelot*
found in Aspergillus niger, a ferment which he was able
to extract, and which inverted maltose and cane-sugar.
The same ferment is also constantly, and in large
quantities, produced by the ordinary yeast, which can only
cause fermentation of cane-sugar by virtue of this ferment.
According to Kjeldahlf the invertin of yeast extract
does not act on maltose. The action on cane-sugar
occurs best between 53° and 56° C., and when the
reaction of the fluid is slightly acid. All the species of
yeast do not produce invertin; thus, EouxJ found a
small round torula, which caused intense fermentation
in solutions of glucose, but which was without action on
Occurrence in cane and milk sugar. — Bacteria also not uncommonly
appear to have the power of inverting these substances ;
this is asserted to be the case by Hueppe, for example,
in the case of the bacillus of the lactic fermentation ; this
organism causes fermentation of cane and milk sugar
only after an alteration of the fluid — as regards the invert-
ing property — has occurred, which alteration is probably
caused by hydratisation. Bourquelot, on the other
hand, concludes from his experiments that the bacteria,
of the lactic fermentation can cause the fermentation of
maltose and cane-sugar directly and without preliminary
inversion. This contradiction is perhaps explained by
the circumstance that the two authors were not working;
with the same species of bacteria. In the case of th&
butyric acid bacilli, it is unanimously agreed that it does
not possess any inverting power ; on the other hand, in
the case of some other species of bacteria Miller has
made positive statements.

3. A ferment which dissolves cellulose is produced
presumably by the bacillus butyricus and by vibrio*
rugula, probably also by various other bacteria. Accu-
rate investigations on this matter are wanting.

4. Peptonising ferments, which convert albuminous
materials into soluble diffusible forms. In addition to

* Bourquelot, Compt. rend,, vol. 97.

t Kjeldahl, Meddedelser fra Carlsberg Labor., vol.i., Parts 2 and 3,

£ fioux, Bull. soc. chim., vol. xxxv.

Cellulose
ferment.

Peptonising
ferments.

CHEMICAL FERMENTS. 579

the ferments of the gastric juice and of the pancreatic
secretions which belong to this group, hodies possessing
a similar action also occur fairly widely distributed
in plants. Thus, from Carica papaya we have papain,
which acts like the pancreatic juice in alkaline solutions ;
then we have a ferment similar to pepsin, which acts when
the reaction is acid, and occurs in those plants which
feed on flesh, and in ^Ethalium septicum. — Ferments of
this class are evidently extremely common in the lower
fungi. The large number of species of bacteria now Occurrence in
known which cause liquefaction of the nutrient gela-
tine, appear to cause this liquefaction only by the pro-
duction of a ferment which dissolves albumen and
gelatine. As the liquefaction usually occurs when the
reaction is alkaline, these bacterial ferments approach
the pancreatic ferment, trypsin and papain, rather than
pepsin. Attempts at isolating these ferments, and
accurate investigations as to the action of the pepton-
ising bacterial ferments on various albuminous materials,
are as yet wanting. The fact that many bacteria liquefy
gelatine, but not solidified blood serum, seems to show
that the various albuminous bodies are not all rendered
fit for assimilation in the same manner, viz., by means
of this production of ferment. — Many bacteria do not
produce peptonising ferment under all circumstances ;
this production seems especially to cease when oxygen
is excluded, just as was observed by Wortmann in the
case of the diastatic ferment of the bacteria.*

5. Rennet ferment. This causes an alteration of Ferment
the albuminoid materials of milk, which shows itself in
the coagulation of the casein. A similar ferment is, as
is well known, present in the stomachs of calves ; and
we may further assume that it is at times produced by
the milk glands, for Meissnerf found that the milk of
goats, even when bacteria were completely excluded,
became coagulated, evidently from a ferment which had

* For further details with regard to this subject see the Paper by
Liborius (Zeitschrift f. Hygiene, i., Part 1) which has appeared while
this book was passing through the press.

f Meissner, Deutsche Zeitsehr.f. Chir., vol. 13, p. 334.

580

VITAL ACTIONS OF THE LOWER FUNGI.

Ferments of
glucoeides.

already appeared in the milk glands. Then Duclaux,*
and, later, Hueppe,f have pointed out that numerous
bacteria show a fermentative action by means of which
they cause the coagulation of the casein of the milk,
where the reaction is amphoteric, i.e., slightly acid, and
slightly alkaline ; afterwards they usually peptonise the
precipitated casein by means of a ferment similar to
trypsin, and ultimately break it up still further. To
this group belong, for example, the butyric acid bacilli ;
and also, according to Hueppe's observations, bacillus
pyocyaneus, bacillus mesentericus vulgatus, sarcina
aurantiaca, &c.

6. Ferments which break up glucosides. These act on
bodies which have arisen by the ether-like combination of
two component elements, in other words, by the loss of water,
one of these components being glucose. By the fermentative
action water is taken up, and the molecule is split up into its
original component elements, hence glucose, and also another
body of very varying composition are formed. The best known
example of this process is the action of the ferment emulsine
on amygdaline, and also that of myrosiiieon myronate of potash;
a similar decomposition is also known in the case of salicine,
of arbutine, of coniferine, of taimic acid, and various other
glucosides. With regard to these, it has not yet been with
certainty made out whether several glucosides can be split up
by the same ferment, for example by emulsin, or whether
here also we must assume the action of specific ferments ; and
nothing is accurately known as regards the occurrence of such
ferments in the lower fungi.

7. A ferment which splits up fat into fatty acids and
glycerine is probably present in pancreatic secretion, pre-
sumably also in many plants and lower fungi.

Urea ferment. 8. The ferment of urea, which breaks up certain
amide combinations in urine with the absorption of
water ; urea is converted into carbonate of ammonium,
hippuric acid into glycocoll and benzoic acid. Formerly
this action was exclusively ascribed to the micrococcus
urese, and Musculus isolated, as he supposed, from these
bacteria the active enzyme which was soluble in water.
According to Ladureau,! this ferment is active in vessels

* Duclaux, Compf. rend., vol. 91.

t Hueppe, Deutsche med. U'och., 1884, Nr. 48 and 49.

J Ladureau, Compt. rend., vol. 99.

Decomposi-
tion of fat.

CHEMICAL FERMENTS. 581

from which the air has been exhausted, also under the
pressure of three atmospheres, and also when oxygen,
hydrogen, or nitrogen are present. According to the
more recent investigations made by Leube, the pro-
perty of splitting up urea belongs to various other
bacteria ; and pure cultivations of the micrococcus urese
proved to be inactive when they were freed from living
micro-organisms by nitration through plaster. It is
possible, therefore, that the ferment isolated by Musculus
did not come from bacteria at all (see page 214).

All the ferments which have been mentioned here are Method of
produced by the organs of higher animals, or by lowly
organisms, but are not so intimately connected with the
life of the producer that it is impossible to isolate and
separate the ferments from the living cells ; when this
is done the products so separated show the same activity.
In the case of numerous ferments such a separation has
been already successfully effected, and we may draw the
conclusion from analogy that, as regards the separation
of the ferments which have not yet been isolated, the
difficulties are chiefly technical, and not insurmountable.
They are usually obtained by precipitation from their
solutions by such means as alcohol, or by carrying them
down with precipitates, and then extracting them from
the precipitate thus obtained by means of solvents
(glycerine, water). The results of chemical analysis
have given the following numbers : —

Carbon. Hydrogen. Nitrogen. Sulphur. Ashes. Chemical

Diastase ... 457 ... 6'9 ... 4t> ... ... 6.1 composition.

Im-ertin ... 40'5 ... 6'9 ... 9'5 ... ... -

Emuisin ... 48'8 ... 71 ... 14'2 ... T3 ... -

Papain ... 52'2 ... 71 ... 16'4 ... ... —

As regards the analyses as yet made, however, it is
probable that the ferments were far from pure ; by
cleansing them as far as possible, more especially from
dextrine and gum-like bodies, Loew* obtained ferments
which approach albuminoid bodies in their composition
much more than those which had been previously

* Loew, Pfluger's Arch., vol. 27.

582 VITAL ACTIONS OF THE LOWER FUNGI.

Analysis of analysed. Thus Loew found in the case of the pan-

ferments. creatic ferment, which in a pure condition occurs as a

snow-white powder, carbon= 52*75 per cent. ; hydrogen

= 7*51 per cent. ; nitrogen = 16*55 per cent. ; oxygen +

sulphur = 23'19 per cent. ; ashes = l*77 per cent.

Selmi* states that he has obtained from urine two
crystalline diastatic ferments, the one crystallising in
the form of microscopic dice, the other like a fern leaf.
Mode of action The mode of action of these ferments may he generally
ferment?. characterised, by saying that they produce hydrolytic
decompositions; that is to say, every molecule of the sub-
stance which is being split up breaks up into two or more
molecules by taking up one or several molecules of water.
In correspondence with this, the decomposition in the
case of some of the ferments mentioned above would
occur in the following manner : —

(1) Diastase : C24H4002l) + 3 H20 = C6H, ,,05 + 3 C6H120,,.

Starch. Dextrine. Dextrose.

or, according to more recent views:

C36H62031 + 2 H,0 = 2 C6HI005 + 2 (C12H22On + H.O).
Starch. Dextrine. Maltose.

(2) Invertin: CI4HMOM + H,0 = C6HI2Od + C.H.Ai-

Cane-sugar. Dextrose I/Eevulose.

(3) Emulsin : C20H27NO , , + 2 H,0=2 CfcHI2Oo+ C6H5.COH + CNH.

Amygdalin. Dextrose. Oil of bitter Hydro-

almonds. cyanic
acid.

C13H1807 + H,O == CdH,aO,i + C«H4 OH, CH2 OH.
Salicine. Dextrose. Saligenine.

C16H2208 + H.,0=C«:HIaOfl + C6H3 ^ C3HU OH.

Coniferin. Dextrose. Coniferyl alcohol.

(4) Ferment of urea : CO,NH2, NH2 + 2 H2O = C03 (NH4) 2.
Urea. Carbonate of ammonia.

In the case of some of the other ferments, for
example, the peptonising one, we cannot make anything
like an accurate formula for the transformation; but it
is probable that in all, the decomposition takes place in
a similar manner by the taking up of water.
Similar action Numerous other chemical agents are also capable of
playing the same part as we have observed in these
ferments. When boiled with dilute sulphuric acid,

Seimi, Aid dei Lincei, vol. 5.

CHEMICAL FERMENTS. 583

starch undergoes a similar transformation to that caused
by the action of diastase ; cane-sugar, the same transfor-
mation into dextrose and laevulose as by invertin ; super-
heated steam splits up fat; continuous boiling with
water peptonises albumen. As a difference between the
action of these chemical agents and that of ferments, it
has been suggested that the latter take such a slight
part in the decomposition that they can split up un-
limited quantities of the fermentescible bodies ; but as
SL matter of fact such an unlimited action does not, by
any means, appear to be the case. On the contrary, in
the case of pepsin, ptyalin, diastase, &c., there are dis-
tinct limits to the action; thus, diastase can, at most,
act on two thousand times its quantity of starch. Under
-ordinary circumstances it is scarcely likely that all of
this power will be employed, because the ferment becomes
injured by the alteration of the substratum, or is par-
tially precipitated in most fluids by the occurrence of
precipitates.

The sensitiveness of the ferments towards external Dependence
influences is comparatively great. As regards the tern- j^ti™ action1"

perature, in the first place every ferment has an optimum, on external

. . ,, i i n T influences.

which, however, is not constant in all cases, but depends

on other circumstances simultaneously present. In the Temperature.

case of diastase, the optimum is about 63° C. (Kjeldahl,

loc. cit.); in the case of emulsin about 50° C. ; in the

case of ptyalin about 46° C. Diastatic action has been

observed even at +5° C. ; from that point it increases

with increasing temperature till it reaches the optimum.

Between 65° and 75° C. we usually observe a complete

cessation of the fermentative action, and a permanent

loss of the fermentative power; the longer the heat is

•continued, so much the lower degrees of temperature

suffice for this action. The addition of glycerine raises

the degree of the hurtful temperature; the addition of

alcohol acts in a converse manner. These numbers,

however, are only valid as regards moist prepara-

tions ; in the dry state the isolated ferments can be

heated from 120° to 160° C. before they are injured. —

Among other circumstances which influence them may

584 VITAL ACTIONS OF THE LOWER FUNGI.

Action of be mentioned the reaction of the medium. Excess of
alkali is injurious to most of the ferments. A slight
degree of acidity is very well home hy some ferments-
diastase, invertin — and their action is, in fact, increased
hy a slightly acid reaction; the pepsin-like ferments
absolutely require a certain excess of acid for the develop-
ment of their action. Other ferments, such as emulsin,
are hindered in their action even hy '15 per thousand of
hydrochloric acid (Falk*). Larger amounts of acid are
always injurious. — The salts of the heavy metals, and
other substances which precipitate albumen, act of course

Carbolic acid, after the manner of poisons. Carbolic acid interferes
with the fermentative action of emulsin and ptyalin;
other ferments, and more especially diastase, are, on the
contrary, scarcely affected; according to Kjeldahl (loc.
cit.) the addition of '2 and '4 per cent, causes a scarcely
noticeable diminution. On the contrary, on the addition
of '03 per cent, of salicylic acid a marked diminution of
the diastatic effect is observed, and on the adition of '1
per cent, the action entirely ceases. — Peroxide of hydro-
gen, which hinders all the fermentations dependent on
the presence of living organisms (Bert and Regnardf),
and also hydrocyanic acid, chloroform, ether, benzole,
and oil of turpentine, scarcely injure the isolated ferment
at all ; and, for example, by the salts of ammonia (up
to 10 per cent.) and by alkaloids, such as veratrin and
curare, the inversion of cane-sugar is much favoured.

Most of the ferments act only on a certain class of
chemical bodies; it is only combinations which are
closely allied to each other which are, as a rule, broken
up by the same ferments. Thus emulsin splits up
several glucosides; but, on the other hand, invertin, for
example, does not act on dextrine, maltose, or starch ;
nor does diastase act on cane-sugar, or on glucosides.
If several chemical ferments are present in the same
solution they may destroy each other ; thus pepsin
digests trypsin and ptyalin. This, however, does
not hold good in the case of all ferments, for diastase

* Talk, Virckow's Arch., vol. 93.

t P. Bert und Eegnard, Compt. rend., vol. 94.

CHEMICAL FERMENTS. 585

and rennet, for example, do not interfere with each
other at all.

As to the mode in which the soluble ferments act, we Attempts to
can make no definite hypothesis. We may perhaps actionof the
suppose that the ferment acts as a carrier of the water ferments.
to be taken up ; that it, in the first place, takes up the
water itself, and then hands it on to the molecules which
are breaking up. Or, according to Bunsen-Hiifner we
may picture the contact and fermentative action by
supposing that the ferment, like sulphuric acid in the
formation of ether, has a greater affinity for certain
atoms or groups of atoms of the molecule which is being
broken up than the remainder has, and thus brings
about a new grouping of the atoms, after the com-
pletion of which it is again regenerated. Both these
hypotheses want the support of any actual demon-
stration that water is taken up, or that any such
combinations of the ferment occur. A third view,
put forward by Nageli, is closely allied to that last
mentioned, but also harmonises with the hypothesis
put forward by Nageli as to the process of fermenta-
tion, which will be referred to below; according to
this view the ferments do not themselves enter into
combinations, but only act on definite groups of atoms
by the condition of movement of their molecule s, and
thus cause a transformation and new grouping of the
elements.

In whatever way the action of ferments may be Distinction
ultimately explained, it is clear that we have here to action of
do with another kind of process than that which occurs
in the true fermentations. The ferments are soluble
chemical bodies, not necessarily united with living
organisms which are only able to set up hydrolytic
decompositions, while in the true fermentation com-
plex alterations of groups of atoms occur which
require the constant presence and the immediate action
of living organisms. The great difference in both
these processes is most clearly evident from a com-
parison of the external conditions which favour or
injure them ; the soluble ferments act best at a

536 VITAL ACTIONS OF THE LOWER FUNGI.

temperature of about 60° C., and when the reaction is.
acid and comparatively large quantities of peroxide
of hydrogen, carbolic acid, oil of turpentine, &c.,
hardly weaken their action, while under the same
conditions we constantly observe a complete cessation of
the life, or, at any rate, of the fermentative activity of
all micro -organisms.

7. Fermentation.

Definition of Under certain circumstances we find a deviation in
on- the biological behaviour of micro-organisms, which is
accompanied by a very thorough decomposition and con-
sumption of the nutrient material, and the formation of
special products, characterised by their quality and
quantity. Among these products, volatile gases usually
take a prominent place ; and in addition bodies are con-
stantly formed of less heat-producing power than those
materials from which they are derived, and thus in the
process of decomposition there is constantly a liberation
of vital energy. The sum total of these phenomena is
usually designated by the term " fermentation."

Fermentation must also, at any rate ultimately, be
referred to decompositions in the protoplasm, to the
intramolecular respiration. We may suppose that the
act of fermentation was evolved from this respiration, and
that it originally only represented an act of self-preserva-
tion due to the continued absence of oxygen. Without
active combustion by the aid of oxygen, the internal
respiration alone is not able to furnish sufficient energy
for the purposes of the organism. When oxygen is
absent, the nutrient material is split up superficially, it
is true, but so much the more extensively, and thus
the energy which is requisite for the complete life of the
micro-organisms is obtained. In the course of their further
evolution the organisms become divided into two great
groups : in the one, the fermentative action only occurs when
there is necessity for it owing to the absence of oxygen ;
in the other, the fermentative action which corresponds
to those special conditions has been gradually developed

FERMENTATION. 587

into a constant property, and these organisms excite
fermentation even when the presence of a plentiful
supply of oxygen does away with the necessity for the
act, the fermentation occurring whenever they are pro-
vided with fermentescible materials.

A sine qua non for the occurrence of fermentative Classification
action is the presence of fermentescible material. Rations ac™
Only a limited number of chemical bodies form suit- J^J
able materials, and it is not every one of the substances bie material.
which are capable of undergoing fermentation which
can be broken up by all of the fermentative agents;
on the contrary, each substance is only decomposed by
one or a few organisms, and every species of bacteria is
limited to a few suitable substances. In the case of
many micro-organisms no body is as yet known which
they are able to split up by fermentation. It is possible
that the functions of these organisms are always limited
to the ordinary respiratory tissue changes ; but it is
possible that, in the case of one or other of these
bacteria, the necessary fermentescible substance will yet
be found.

It is only by the consideration of individual cases that
we can recognise and understand the nature and pro-
perties of the material suitable for fermentation, as well
as the mode in which it is split up by the fermentative
action. We differentiate a large number of specific
fermentations, which receive their names either from
one or a few characteristic products, or from the nature
of the fermentescible material, or, finally, from the fer-
menting agent. In what follows we shall describe, in
the first place, fermentation by the yeast fungi ; then
the various fermentations caused by bacteria, which may
be divided into five groups, viz., a. Fermentation of
carbo-hydrates ; /3. Fermentation of the higher alcohols
(glycerine, erythrite, mannite) ; y. Fermentation of the
fatty acids ; §. Putrefaction ; * . The formation of acetic
acid from alcohol.

588 VITAL ACTIONS OF THE LOWER FUNGI.

A. Alcoholic Fermentation of Suyar by Yeast.

Fermentesci- The fermentescible material is furnished by the
le material. giucoseg of the formuia C6H1206, namely, dextrose,

Isevulose, lactose, or galactose ; further, by maltose, to
which the formula C18H34017 is given, and which, there-
fore, only acquires the same composition as glucose by
taking up water. Dextrose forms the most favourable
material ; if it is exposed to fermentative action in a
mixture along with other forms of glucose, for example,
laevulose, the dextrose is the first to undergo fermenta-
tion.— Cane-sugar and milk-sugar only undergo fermen-
tation when they are converted into glucose ; the former
can be converted into dextrose and laevulose by means
of invertin (therefore by yeast), the latter is transformed
into galactose and dextrose by means of a ferment pro-
duced by some fungi ; further, they can both be converted
into these glucoses by boiling with dilute mineral acids.
— Other carbo-hydrates also, such as starch, gum, and
cellulose, can be converted into glucose by ferments, or
by treatment with acids ; starch is transformed into
dextrose by means of ptyalin and also by acids, and into
maltose by diastase (malt). — All the carbo-hydrates last
mentioned can therefore, in like manner, serve for fer-
mentation, if only ferments which transform them into
glucose are at the same time present in the fermenting
mixture ; and as these ferments are usually produced in
large quantities by the same organisms which cause the
fermentation (invertin by yeast, the ferment which trans-
forms milk-sugar by bacteria), the incapacity of cane-
sugar, starch, &c., to undergo fermentation directly is
practically of little account, and fermentation frequently
occurs when these substances are present, and when the
directly fermentescible glucoses are absent, being at
most somewhat delayed in its commencement. By
being provided with ferments which form glucose, the
area of the vital and fermentative activity of the fer-
mentative agents is markedly enlarged.

Forms of The specific decomposition of glucose into alcohol

yeast capable an(j carbonic acid is limited to yeast, but all the species

of exciting *

fermentation, of saccharomyces are not able to set up an equally

ALCOHOLIC FERMENTATION OF SUGAR BY YEAST. 589

energetic fermentation. Two species, beer and wine
yeast, act most powerfully. The former is constantly
cultivated in beer wort ; fresh fermentation is set up by
the addition of the yeast from fermenting wort to fresh
fermentescible fluid. According to the more or less
violent progress of the fermentation, high or low yeast
is obtained; in the former the budding takes place more
rapidly, and we thus obtain groups of cells which are
readily taken up by the stream of carbonic acid and
carried to the surface. The wine yeast — S. ellipsoideus
— is the form which is most widely distributed in
nature ; it establishes itself spontaneously in the most
various saccharine solutions when exposed to the
entrance of air, or it is introduced into these, for ex-
ample, by the skins of the grapes, on which it is con-
stantly found. The other forms of yeast, S. apiculatus,
exiguus, &c., appear to possess a less degree of vegeta-
tive energy and fermentative action. In the case of
some, as, for example, pink yeast (rosa hefe), no fermen-
tative action has, as yet, been noted ; mycoderma only
excites a temporary and trivial fermentation when it is
artificially compelled to grow at the bottom of fluids.

The yeast-like growths of some of the mould fungi Fermentative
have a more powerful fermentative action than the forms mould and
of yeast last mentioned, in that, when immersed in sugar fission
solution, they set up a fairly energetic decomposition of
the sugar, with the formation of alcohol and carbonic
acid ; at the same time they approach true yeast in
their conditions as regards form and growth. These
properties are most marked in Mucor racemosus, M.
cercinelloides, M. spinosus ; they are less developed in
Mucor mucedo, and hardly at all in Mucor stolonifer. —
Other mould fungi are also able to produce traces of
alcohol and carbonic acid when they grow in saccharine
solutions in the absence of oxygen ; but the amount
produced cannot be at all compared with that formed by
the species of mucor and by the true yeasts, and only
depends on the intramolecular respiration, by means of
which also the cells of any of the higher plants can
form alcohol and carbonic acid. — Further, in the fer-

590

VITAL ACTIONS OF THE LOWER FUNGI.

Chemical
processes in
this fermen-
tation.

mentation of carbo-hydrates by bacteria, we have not
uncommonly a plentiful formation of alcohol and
carbonic acid (see below) ; but. in this case, numerous
other products constantly arise, so that the amount of
alcohol is relatively unimportant. Hence the produc-
tion of alcohol and carbonic acid is not of itself
characteristic for the fermentation by yeast. What is
characteristic is the enormous and almost exclusive for-
mation of these bodies from definite kinds of sugar, and,
in contrast to the organisms which only have a similar
action when air is excluded, the circumstance that the
presence of oxygen does not hinder the formation of
these substances, but rather favours it.

The mode in which glucose is broken up in the fer-
mentation by yeast was formerly represented by a very
simple chemical formula. It was believed that the
glucose molecule was split up into two molecules of
alcohol, and two molecules of carbonic acid : C6H1206
(glucose) = 2 C2H5, OH (tethyl-alcohol) +2 C02.
Pasteur, however, showed that a number of other sub-
stances constantly appeared, even when the fermentes-
cible materials and the yeast were, as far as possible,
pure ; on an average 2 '5 to 3' 6 per cent, of the ferment-
ing sugar appeared in the form of glycerine (C3H5
(OH)3), and *4 to *7 per cent, in the form of succinic
acid (C2H4 (COOH)2) ; and further, there were con-
stantly traces of acetic acid, and often of other alcohols,
such as amyl-alcohol. The attempt has been made
to include these side products by the formula 49
(C6H1206) (glucose), +30 H20 = 12 C4H604 (succinic
acid), +72 C3H803 (glycerine), +30 C02 (Pasteur),
or by the formula 4 C6HJ206 +3 H20 = C4H604
+ 6 C3H803 +2 C02 +0 (Monoyer) ; but this attempt
has not been successful in giving a correct view of
the quantitative conditions. — The same bye -products
are also found in the fermentation by the yeast forms
of mucor ; at any rate Fitz was able, in this case,
to demonstrate succinic acid with certainty. Further,
Brefeld found that the bye-products were the more
plentiful the more unfavourable were the nutrient con-

ALCOHOLIC FERMENTATION OF SUGAR BY YEAST. 591

ditions for the fermentative agents. Towards the end
of the fermentation these materials seem to accumulate,
and those fermentative agents which are only able to set
up the fermentation with difficulty, and which in reality
require other conditions of existence, furnish bye-pro-
ducts in especially large quantities; for example, Mucor
inucedo furnishes more than Mucor racemosus, and
Mucor stolonifer more than Mucor mucedo.

We may, perhaps, suppose that in succinic acid, Significance
glycerine, &c., we have represented the special products products.
of the tissue change of the yeast. As a matter of fact
we must assume that, in addition to the splitting up of
the sugar, there also occur decompositions, and, where
oxygen is present, oxidations of the complex molecules
of the protoplasm of the yeast, which are composed of
nitrogenous and non-nitrogenous groups of atoms ; as a
consequence the ordinary products of the destructive
tissue change appear in the nutrient mixture. It
is, however, difficult to identify these products with
those bye -products which appear in fermentation ; the
quantity of the latter is much too great, and their
quality also is too peculiar. Further, in this case, tbe
amount of the bye-products must be proportional to the
amount of the active yeast cells which are present, and
must also, in the first place, depend on the quantity
which has been sown. But as yet nothing has been
observed as regards any such relation. We must there-
fore either assume that the decomposition of the sugar in
the fermentative action in reality occurs, at any rate as
regards the largest amount, according to a more com-
plicated formula, in which there is a constant formation
of glycerine and succinic acid ; or that the appearance
of these bye-products is caused by impure fermentescible
material, by the admixture of bacteria, and by their
decomposition of the nutrient materials. The possi-
bility of such impurities must be admitted in the case
of the experiments which have been as yet made, in
spite of the great precautions which have been taken
by various authors since the time of Pasteur, because it
was not possible, in the earlier methods, to isolate pure

592 VITAL ACTIONS OF THE LOWER FUNGI.

Employment species of yeast. It is only within the last few years
yewrtin1* tn&t Hansen has heen able to obtain a completely pure
expTrhnents matei'ial> ^J using Koch's solid nutrient media, and we

must await the results obtained by chemical analysis, in

the experiments made with this yeast.

Self ferment- Very special attention has been paid by many investigators
ation of yeast. to the so.caned "self-fermentation" of yeast. This occurs
when large quantities of fresh, active yeast is left to itself in
the presence of a plentiful supply of water, insufficient
entrance of air, and a favourable temperature (25° to 30° C.).
Under these circumstances a large amount of carbonic acid
and alcohol are formed, the yeast becomes soft, and gives with
warm water an extract containing numerous substances,
which must be looked on as products of tissue change and of
decay. According to the investigations of Bechamp and
Schiitzenberger the water contains albuminoid substances,
gum, a ferment rotating to the left, a substance called zymase,
pseudo-leucin (with which a varying quantity of sulphur is
mixed), tyrosin, butalanin, carnin, xanthin, guanin, sarkin. —
The substances last named are evidently derived from the
decomposition of albuminoid materials ; the production of
carbonic acid and alcohol, however, can only be explained
either by the presence of f ermentescible sugar in the yeast, or
by the ready conversion of some constituents of the yeast cell
into sugar ; in that case the substance from which the sugar
is derived will belong either to the group of carbo-hydrates,
such as cellulose or gum, or to the group of proteid substances.
According to Pasteur, material resembling sugar is always
present in yeast, this material being very difficult to extract
as such, but becoming converted into sugar by mineral acids,
for example ; and it is this, along with the cellulose of the
cell wall, which furnishes, according to Pasteur's view, the
fermentative products which arise in the self-fermentation.
Another important view was, however, advocated by Liebig ;
he found, in some experiments on the self-fermentation
of yeast, such large quantities of alcohol and carbonic acid
(8 to 13'5 per cent, of alcohol, of the total weight of the
dry yeast), that the whole amount of cellulose and other carbo-
hydrates contained in the yeast was not sufficient to furnish
this amount of fermentative products ; hence in order to ex-
plain the amount of these substances it was necessary to
assume the occurrence, to a large extent, of a decomposition
of albuminoid substances. Liebig laid the greatest stress on
this decomposition of albuminoid substances because he saw in
it the really essential and constant process which took place
in fermentation ; according to his view, the essence of the

ALCOHOLIC FERMENTATION OF SUGAR BY YEAST. 593

fermentative process is that a complex proteid substance,
when in a state of decomposition, transmits its chemical
movements to other molecules, such as sugar.

Nageli's more recent researches, however, show most dis-
tinctly that, in the self-fermentation of yeast, the process
which takes place is not limited to, and only dependent on?
the yeast ; but that, in the former experiments, without doubt
bacteria also acted and took part in the decomposition of the
substance of the yeast. In fact the very circumstances under
which the self-fermentation was observed were such that of
necessity an active development of bacteria must occur ; these
lived and multiplied at the expense of the dead yeast cells, and
probably also set up fermentative processes in certain of the
constituents of the yeast substance which had been rendered
•soluble by ferments given off by them. A portion of the
nitrogenous derivatives found in the extract may result from
the activity of these bacteria, which can probably also take
part in the production of carbonic acid and alcohol. Nageli
so arranged the experiments that when, for example, by the
addition of citric acid, the development of bacteria was
rendered difficult, only minimal traces of alcohol were found,
probably derived from the small quantities of saccharine sub-
stances which are contained in the yeast cells, and which
underwent fermentation when no saccharine nutrient material
was at the disposal of the yeast. This process would be quite
analogous to the decompositions which occur in starving
animals. But we have no grounds for believing that the
proteid substance of the exhausted yeast cells can be utilised
hy other living yeast cells ; because the ferments necessary
for the solution of these substances are not found in yeast.
Further experiments, in which attention is paid to the
purity of the cultivation, are therefore required to give definite
information as to the real extent of the self -fermentation of
the yeast, and as to the products of tissue change.

Cochin * has attempted to ascertain the time required The time
for fermentation, by continuous measurement of the Jequire? £.or

J fermentation.

amount of carbonic acid developed. He found that in
the first instance ten to twenty minutes always elapsed
"before active fermentation commenced ; and the time
was still longer in dilute solutions. From that time
onwards the course of the fermentation may be expressed
by a steeply ascending line, which finally ends in the
form of a parabola. This period of incubation does not
mean that the saccharine solution must first penetrate

* Cochin, Cumpt. rend., vol. 06.

38

594

VITAL ACTIONS OF THE LOWER FUNGI.

Influence of
various con-
ditions on the
quantitative
result.

Amount of
sugar.

Quantity of
yeast.

Accumulation
of alcohol.

Temperature.

into the interior of the yeast cells, and that for this a
certain time is required ; for the same phenomenon is
observed when the yeast is implanted in a new solution
directly from a solution in active fermentation.

The quantitative result of the fermentation undergoes
marked variations according to the composition of the
fermenting material, according to the quality of the
yeast, according to the length of time, and according to
various external influences.

The amount of sugar in the solution must not exceed
35 per cent., for otherwise the yeast cells suffer for want
of the proper quantity of water ; the best proportion of
sugar seems to be 2 to 4 per cent., and then 20
to 25 per cent. (Wiesner), but this striking fact of
two optima requires confirmation. The quantity of
yeast added is, within certain limits, irrelevant for the
progress of the fermentations. Dumas found that one
gramme of sugar was completely broken up at 24° C.
by 20 grammes of yeast within twenty-four minutes ;
the addition of 100 grammes of yeast did not alter this
result in the slightest. Where a large amount of yeast
is added intense fermentation occurs, even in pure solu-
tions of sugar, which ultimately ceases, leaving behind
a yeast which is exhausted and poor in nitrogen ; if it
is desired to keep up a permanent fermentation with
relatively small quantities of yeast, the addition of other
nutrient materials, more especially of nitrogenous
materials, is necessary. — Further, the continuation of
the fermentation is limited by the accumulation of the
alcohol ; the presence of 12 per cent, of alcohol hinders
the growth of the yeast, and when more than 14 per
cent, is present fermentation ceases entirely. In the
case of the mucor yeast this limit is much lower —
about 34 to 4 per cent, (in the case of Mucor stolonifer
even 1*3 per cent.) ; this form of yeast is also much
more sensitive to great concentration of the sugar solu-
tion, for a satisfactory fermentation only occurs in
solutions containing less than 7 per cent, of sugar
(Fitz). — Of the external influences the temperature is
of chief importance ; as a rule 25° C. seems to be

FERMENTATION BY BACTERIA. 595

the most favourable temperature, but this optimum
varies under the influence of various factors. Further,
the influence of the aeration of the fermenting mixture,
its impregnation with oxygen, is of importance. Accord- Oxygen.
ing to Niigeli, the access of oxygen favours fermenta-
tion in all cases ; chiefly when, at the same time,
materials which offer good nutriment for the yeast are
present in the fermenting mixture, because in that case
a much more active multiplication of the cells can occur.
In investigations recently made by Hansen,* it was
found that the same quantitative results require a longer
time when air is absent, and that, at the same time,
fewer yeast cells are formed and take part in the fer-
mentation ; on the other hand, by continued aeration
the same result is reached in a shorter time, and there
is a much more extensive multiplication of the cells.
Therefore, under the influence of the presence of oxygen
the formation of the cells and the occurrence of fermen-
tation takes place more quickly, but the action of the
individual cells is not, on an average, so great as when
air is absent. — Of chemical agents which disturb or
hinder fermentation may be mentioned free alkalies, also
sulphurous acid, sublimate, chloroform ; while sul-
phuretted hydrogen, arsenious acid, carbolic acid, sali-
cylic acid, strychnine, hydrocyanic acid, only hinder the
fermentation of yeast when markedly concentrated, or do
not affect it at all.

As regards the fermentation of bread, kephyr, koumiss,
see page 607.

B. Fermentation by Bacteria.
(a). Fermentation of Carbo-Jiydrates.

The carbo-hydrates furnish, under the influence of Fermentation
various bacteria, a lactic fermentation, a mucous dr
mannite fermentation, a butyric fermentation, a dextran
fermentation, and, finally, some fermentations in which
nethylic alcohol and various other products are formed.

* Hanson, Meddekherfra Carlsbcrg Lab.: vol. i., Part 2.

59G VITAL ACTIONS OF THE LOWER FUNGI.

Lactic Fermentation.

fermentation ^^e mater^a^s necessary are grape-sugar, cane-sugar,
milk-sugar, marmite, sorbite, inosite. Cane-sugar and
milk-sugar are probably in the first place converted into
glucose. Spontaneous fermentation is most frequently
observed in milk ; it probably also plays a part in the
preparation of bread and leaven, and frequently occurs
in the fabrication of starch, and in the saccharine juice
of beet-root. We can artificially obtain a lactic fer-
mentation either by leaving milk to stand at about
30° C. for three or four days, or by mixing a weak sugar
solution with somewhat old cheese and with purified
chalk, and keeping the mixture for several days at
30° to 35° C. ; in the latter case the lactate of lime
which is formed can be easily obtained (see Schiitzen-
berger, page 172).

Fermentative The bacillus acidi lactici is in most cases the exciting
agent of the fermentation. But the lactic fermentation
is by no means confined to this one species of bacterium,
but, on the contrary, a large number of cocci and bacilli
which have been mentioned above, share with it the
fermentative power, and are only distinguished from it
by the fact that the quantitative result of their action is
much less, and that they are by no means so widely dis-
tributed as the ordinary lactic acid bacillus. Hence in
all spontaneous fermentations we find that the lactic
bacilli usually take part, and generally in much the
largest numbers.

Nature of the The nature of the chemical decomposition has not yet

tion°mp been completely explained. Formerly the attempt was

made to explain the decomposition of sugar in the lactic
fermentation by the simple formula, CJI^06 (glucose) =
2 (C2H4, OH, COOH) (lactic acid), and Miller also
states that he has observed in the case of some bacteria
this simple decomposition of the molecules of sugar.
Such a process, without any development of gas, and
without any more marked alteration in the molecule,
could not be regarded as fermentation according to the

FERMENTATION BY BACTERIA. 597

definition given both in tins work and also by various
other authors.

As a matter of fact, development of carbonic acid is
always observed in the ordinary lactic fermentation ; and
Bontroux, as well as Hueppe, has observed the develop-
ment of carbonic acid in fermentation set up by pure
cultivations of lactic acid bacteria. Former observers incomplete-
have also found, besides carbonic acid, other fermentative previous 6
products (alcohol, butyric acid, mannite, gum). It is formula,
probable that these substances often owe their origin
only to the simultaneous presence of adventitious
organisms which stand in no relation to the lactic fer-
mentation ; nevertheless, it is not by any means a priori
impossible that the various bacteria which are capable of
setting up lactic fermentation can occasion decomposi-
tions which are dissimilar, and combined with a larger
number of bye-products. In any case, however, the
above formula is incorrect for the lactic fermentation by
the bacillus acidi lactici, because no account is taken in
it of the carbonic acid which is constantly observed.

The course of the fermentation and its dependence on
various external conditions has been already discussed
on page 365.

Butyric Acid Fermentation.

The materials for this fermentation are furnished by Butyric acid
starch, dextrine, inuline, cane-sugar, and dextrose ; and fermentation.
also by milk-sugar, but only after hydration. The
butyric acid fermentation occurs spontaneously, and
is very widely distributed ; thus it is found in milk
which has stood for a long time, in " sauer-kraut," in
cheese, in the ripening of which it probably plays a
part, &c. In order to obtain it artificially it is well,
according to Fitz, to mix together 100 grammes of
potato starch (or dextrine), one gramme of sal ammoniac
and the ordinary nutrient salts, with two litres of water,
and to add 50 grammes of carbonate of lime, in order to
neutralise the butyric acid as it is formed. According

598 VITAL ACTIONS OF THE LOWER FUNGI.

to Deherain* and Maquetme the exciting agents of the
butyric acid fermentation are found in large numbers in
the earth of fields and gardens ; hence it is best to infect
the fermentescible mixture with this, or with old cheese,
or with cow dung. The vessels are then kept at 40° C.
Fermentatire While formerly it was only supposed that one species
of bacterium had the power of exciting the butyric fer-
mentation, it has been recently demonstrated that several
species of bacteria are capable of this act, and that the
fermentation with one or with some forms of bacteria
can occur in the presence of air, while for the activity
of others the exclusion of air is a necessary condition.
Besides the species mentioned on page 367, it seems,
according to Fitz,t that a short cylindrical bacillus,
described by him, is capable of setting up butyric fer-
mentation, this bacillus possessing a moderate amount
of spontaneous movement, not forming spores, and not
becoming blue on the addition of iodine. It belongs to
the class of aerobes, and causes fermentation of all carbo-
Nature of the hydrates except starch and cellulose. — The formula for
tion°mP°S ^e decomposition is probably different for the various
different species; in any case, carbonic acid and hydrogen
seem to be constantly formed in large quantities. Fitz
has also found on analysis of the products obtained from
a hundred grammes of starch, 34'7 grammes of butyric
acid, 5'1 grammes of acetic acid, and 1 gramme of
sethylic alcohol. As, however, it has, as yet, been
scarcely possible to cultivate the butyric acid bacilli
perfectly pure, no experiment with absolutely pure
cultivations has been subjected to accurate analysis,
and therefore we must not lay too great weight on
these numbers. See page 369.

Viscous or Mannite Fci mentation.
Viscous for- T^ materials which furnish this fermentation are

mentation ot

wine. dextrose and invert sugar ; as regards the ferment, the

micrococcus viscosus, see p. 216. The fermentation

* Deherain et Maquenne, Bull. soc. chem. (2) vol. 29 — Compt. rend
vol. 97-

t Fitz, Chem. Ber., vol. xvii., P. 1188.

FERMENTATION BY BACTERIA. 599

often occurs in certain kinds of wine, more especially in
white wine, also in the saccharine juices of turnips,
carrots, onions, &c. ; the fluids attacked become viscous
and can he drawn out in threads. The fermentation is
best obtained artificially by using a decoction of beer
yeast, which is filtered and mixed with sugar, or by
employing starch, rice, or barley-water containing sugar ;
the optimum of temperature is about 30° C. Among
the products of fermentation is always a kind of gum,
which is closely related to dextrine, and has been recently
termed by Bechamp " viscose " ; mannite and carbonic
acid are also formed. Viscose is soluble in cold water, Viacoae.
is precipitated by alcohol, does not reduce Fehling's
solution, shows the same composition as starch, and
rotates in the same manner as soluble starch. — At times,
and probably owing to the action of other ferments,
lactic acid, butyric acid, acetic acid, and hydrogen are
formed. Under the most favourable circumstances 100
parts of sugar yield 51 '1 parts of mannite, 45 '5 parts of
gum, and 6'2 parts of carbonic acid; hence the fer-
mentation can be expressed by the formula, 50 (C6H1206)
(dextrose) = 12 (C12H20010) (gum) +24 (C6H1406) (man-
nite) + 12 CO,, f 12 H20. Schmidt-Miilheim supposes
that, in this fermentation of wine, there are, in fact, two
fermentations taking place together ; the one which pro-
duces mannite and carbonic acid, and the other as the
result of which the gum-like substance arises. — Schmidt-
Miilheim observed the formation of the latter substance
alone without simultaneous production of carbonic acid
and mannite in the so-called tenacious milk as the result Viscous fer-

mentation of

of the growth of the micrococcus described on page 21b. milk.
This fermentation is not a fermentation of the albuminoid
materials of milk, but is due to splitting up the milk-
sugar, or it may be also cane-sugar, grape-sugar, or
mannite. The viscous substance formed is precipitated
by alcohol as a white sticky precipitate, which only swells
up slightly in water, much more freely in potash lye>
readily reduces Fehling's solution, and is stained brown
by iodine and iodide of potash. — The optimum of tem-
perature for this fermentation lies between 30° and 40° C.

600 VITAL ACTIONS OF THE LOWER FUNGI.

Dextran Fermentation.

fermentation ^e only directly suitable material is grape-sugar;
cane-sugar does not ferment directly, but, as the ferment-
ing agents furnish large quantities of invertin, the
decomposition of the cane-sugar is only slightly delaj'ed.
It not uncommonly occurs spontaneously in the juice of
beet-root, and hence is much dreaded in sugar factories.
The fungus which causes the fermentation is leuconostoc
mesenterioides. The decomposition results mainly in
the formation of large quantities of a jelly-like sub-
stance— the dextran. We have no accurate knowledge
as to the process of the fermentation ; as to the morpho-
logical characters of the fungus, see page 214.

Cellulose Fermentation (Marsh Gas Fermentation}.

Cellulose Cellulose, in the form of dead plants, straw, paper, or

cotton-wool, frequently undergoes solution and fermen-

Materials and tation by bacteria. Hoppe-Seyler * was able to set up this
fermentation by all kinds of mud, and also by earth from
fields, meadows, and woods; according to Deherain t and
Gayon J it often occurs in dung; on the whole, it seems
to be extremely widely distributed. Tappeiner has
shown that cellulose is dissolved and broken up by the
same fermentation in the intestinal canal of the rumi-
nants.— The bacteria which set up this fermentation
have not, as yet, been cultivated pure. As to the
chemical processes, Tappeiner has made several inves-
tigations, and found that there are two kinds of fermen-
Cation of cellulose ; the first occurs in neutral extract of
meat solution containing 1 per cent, of extract of meat,
in which purified cotton-wool or paper pulp is suspended;
under these circumstances, carbonic acid and marsh gas
escape (in the first few days the marsh gas is in much
greater excess than at a later period); further, small

* Hoppe-Seyler, Chem. Ber., vol. xvi.

t Deherain, Compt. rend., vol. 9P. J Gayon, ibid.

FERMENTATION BY BACTERIA. 601

quantities of sulphuretted hydrogen, aldehyde, isobutyric
acid, acetic acid. The second fermentation occurs when Second kind.
an alkaline extract of meat solution is employed; in that
case only carbonic acid and hydrogen are formed, along
with the same bye-products as in the former fermenta-
tion.— Tappeiner* has ventured to conclude from his
researches that the solution and decomposition of cellu-
lose in the intestine of ruminants only occurs as the
result of this fermentation, and that therefore the cellu-
lose is of no nutrient value for the organism. According
to the experiments and calculations of Wilsingt and
Henneberg and Stohmann, J however, this view does not
seem to be accurate, and only a part of the cellulose
which disappears in the intestine is lost by fermenta-
tion.

Other Fermentations.

In the case of various carbo-hydrates, Fitz observed a fer- Various other
mentation in which sethylic alcohol was formed as the chief fermentations,
product. From 500 grammes of starch he obtained 10 grammes
of aethylic alcohol; from the same quantity of dextrine 22
grammes ; milk-sugar also furnished chiefly the same alcohol.

Bontroux found a transformation of milk sugar into gluconic
acid by a species of bacterium similar to themycoderma aceti.

To Brieger we owe the knowledge of a number of fermenta- Fermenta-
tions of carbo-hvdrates caused bv pathogenic bacteria. Ac- ti°ns by .

, . J , . 1., °,., ..pathogenic

cording to this author bacillus cavicida splits up solutions or organisms.

grape-sugar in such a way that propionic acid is the chief
product. Bacillus pneumonias causes a marked development
of gas in five per cent, sugar solutions to which a little
nutrient gelatine has been added, and in the fluid there is
acetic acid as the chief product of the fermentation, and, in
addition, small quantities of formic acid and aethylic alcohol.
Typhoid bacilli formed from grape sugar or starch aethylic
alcohol, acetic acid, and lactic acid. A non -pathogenic
coccus, obtained from faeces, which forms on gelatine flat
pyramids of a glistening white colour, decomposes three per
cent, grape-sugar or cane-sugar solution in such a way that
asthylic alcohol along with traces of acetic acid is formed.

* Tappeiner, Chem. Ber.. vol. IQ.—Zeilschr.f. BioL, vol. 20.

f Wilsing, ibid. £ Henneberg nnd Stohmann, ibid., vol. 21.

602 VITAL ACTIONS OF TEE LOWER FUNGI.

(|3). Fermentation of the Higher Alcohols.

Fermentation While no fermentations have been with certainty
alcohols^ r observed in the case of the diatomic glycol, various
fermentations caused by bacteria have been demonstrated
in the triatomic alcohol, glycerine, the tetratomic alcohol,
erythrite, the pentatomic alcohol, quercite, and the hexa-
tomic alcohols mannite and dulcite.

Glycerine. Jn the case of glycerine, Fitz observed four fermentations.

Under the influence of the bacillus Fitzianus — the morphology
and source of which we have discussed on page 388 — glycerine
furnishes considerable quantities of sethylic alcohol (for ex-
ample, 29 grammes from 100 grammes of glycerine), and, as
bye-products, capronic acid, butyric acid, and a little acetic
acid.

In order to set up the second fermentation, which chiefly
furnishes butylic alcohol, solutions of hay-water and glycerine
are mixed and kept at 40° C. without being previously boiled.
A bacillus is found in the fermenting mixture which is 2 p..
broad, and 5 to 6 /*. long, and which is actively motile while
the fermentation is going on. In stronger solutions of glycerine
(above 10 per cent.) the fermentation soon ceases, and the
bacillus forms spores. If fresh cow-dung is sown in the
glycerine nutrient solution, a3thylic and butylic alcohols are
formed in about equal quantities (also a little propylic alcohol),
and, in correspondence with this, the nutrient solution is
peopled by two forms of bacilli.

Thirdly, Fitz was able to set up a fermentation in glycerine
by means of the bacillus pyocyaneus in which large quantities
of butyric acid, along with a3thylic alcohol and succinic acid,
were obtained.

Fourthly, as the result of the growth of small thin rods,
often united together in pairs, which are also able to set up
fermentation in malate of lime, sethylic alcohol (21 grammes
from 100 grammes of glycerine), and also formic acid and
succinic acid were obtained. — A fermentation of glycerine was
also caused by other bacteria ; thus, as the result of the
growth of microcooci, alcohol, butyric acid, formic acid, and
acetic acid were found; Hoppe-Seyler found, on the addition
of putrefying fibrine to a glycerine solution, chiefly butyric
acid, acetic acid, and succinic acid as products of fermentation.
Vigna* observed the formation of set-hylic and butylic alcohol

* Vigna, Clem. Ber., vol. xvi.

FERMENTATION OF THE FATTY ACIDS. 603

from glycerine, and was dealing therefore probably with the
combination of the two fermentations first mentioned. — In all
these decompositions of glycerine, with the exception, perhaps,
of the fermentation by bacillus Fit zianus, which has been more
accurately studied by Buchner, the methods employed do not
furnish a sufficient guarantee for a thoroughly pure growth,
and the morphological characteristics of the fermenting
agents have not been sufficiently attended to, and thus the
value of these careful chemical investigations is diminished.

In the case of erythrite Fitz also found a number of fer- Erythrite.
mentations ; one bacterium caused a decomposition in which
two molecules of erythrite were split up into one molecule of
butyric acid, and one molecule of succinic acid, with a loss of
2H20 and 1 H; another bacterium caused a fermentation
with only slight traces of succinic acid.

Mamiite, in the first place, gives rise to the lactic fermenta- Mannite.
tion above mentioned. According to Fitz also, a bacterium
causes in a three per cent, solution of mannite the formation
of normal butylic alcohol, sethylic alcohol, succinic acid, and
lactic acid ; and a club-shaped bacillus obtained from boiled
hay infusion furnished aethylic alcohol (26 per cent.), formic
acid (5'6 per cent.), and a little succinic acid.

Dulcite behaves very similarly to the carbo-hydrates as Dulcite.
regards the lactic fermentation. According to Fitz, dulcite
also gives rise to a fermentation with a little alcohol and
much butyric acid. Quercite gives rise to a fermentation
with the almost exclusive formation of normal butyric acid.

(y). Fermentation of the Fatty Acids.

Numerous acids belonging to the group of fatty bodies Fermentation
form a suitable fermentescible material when they are °cids ty
given to bacteria in the form of neutral salts. The lime
salt of these acids seems to be the most suitable, and
with it almost all the experiments on fermentation have
been made. The following are capable of undergoing
fermentation: formic acid (HCOOH), acetic acid (CH3,
COOH); further, a number of oxy-acids, namely:
lactic acid (C2H4, OH, COOH), glycerinic acid (C2H3,
(OH)2, COOH), malic acid (C,H3, OH, (COOH)2), tar-
taric acid (C2H2, (OH)2, (COOH),), citric acid (C8H4, OH,
(COOH)3).

Formate of lime furnishes, according to Hoppe-Seyler,

604 VITAL ACTIONS OF THE LOWER FUNGI.

when mixed with sewer-mud, carbonate of lime, carbonic acid,
and hydrogen ; acetate of lime, treated in a similar manner,
gives carbonate of lime, carbonic acid, and marsh gas.

Lactate of lime undergoes, according to Fitz, four different
kinds of fermentation ; in the first place, under the influence
of a thin bacillus, which often forms long chains, it gives rise
to the propionic acid fermentation, in which acetic acid, suc-
cinic acid, and alcohol appear as bye-products ; the process
may probably be expressed by the formula 3 CaH^ OH COOH
(lactic acid) = 2 C2H5 COOH (propionic acid) +CH3 COOH
(acetic acid) +C02 +H2O. — In the second place, the acetate
of lime under other conditions furnishes, along with propionic
acid, large quantities of normal valerianic acid ; from 3
kilogrammes, 126 grammes of propionic acid and 101 grammes
of valerianic acid were obtained. — Thirdly, as the result of the
action of the short aerobic butyric acid bacilli discovered by
Fitz, butyric acid and propionic acid were chiefly formed. —
Fourthly, Pasteur (Comptes rendus, 1861) long ago observed
the butyric acid fermentation of lactate of lime ; Fitz obtained
in this fermentation, from 500 grammes of lactate of lime,
about 34 grammes of butyrate of lime, and also 3'6 grammes
of aethylic and butylic alcohol. This fermentation may be
represented by the formula 2 (C2H4 OH COO)2Ca (lactate of
lime) = CO3Ca (carbonate of lime) +3 C02 +4 H2 + (C3H7
COO)2Ca (butyrate of lime).

Glycerinate of lime gives, when fermented by longish micro-
cocci, chiefly acetate of lime, along with a little succinic acid
and asthylic alcohol ; the pure fermentation probably occurs
according to the formula (C2H3 (OH)2 COO)2Ca (glycerinate
of lime) = (CH3 COO)2Ca (acetate of lime) +2 C02 +2 H2.
The same material can also be fermented, by means of fairly
large bacilli, to formic acid, with a little methylic alcohol and
acetic acid as bye-products.

Malate of lime can likewise undergo several fermentations.
Under the influence of thin bacilli — the same which caused
the fermentation of glycerine — succinic acid (about 60 per cent,
of the material) and a little acetic acid are formed ; with other
shorter bacilli propionic acid is the chief product, along with
a little acetic acid. — In the third place, there is, at times, a
formation of butyric acid, with the development of hydrogen ;
and finally, according to Schiitzenberger, the malate of lime
is split up with the formation of lactic acid and carbonic
acid.

Tartrate of lime gives rise either to the propionic acid fer-
mentation found by Pasteur, and also obtained by Fitz, which
probably takes place according to the formula 3 C±H6O6 (tar-
taric acid) = C2H5 COOH (propionic acid) +2 CH3 COOH
(acetic acid) -\ 5 C02 +2H.20 ; or butyric acid fermentation

FERMENTATION OF THE FATTY ACIDS. 605

results ; or, in the third place, a decomposition occurs, in which
acetic acid is chiefly formed (from 100 grammes of tartrate of
lime Fitz obtained 45 grammes of acetate of lime), and, in
addition, a3thylic alcohol, butyric acid, and succinic acid.

According to Koenig* there is obtained from a solution of
tartrate of ammonia together with nutrient salts, on the
addition of a drop of putrid fluid, a slight development of gas
(carbonic acid and hydrogen), a large quantity of succinic
acid, and a little formic acid and acetic acid. From tartrate
of lime infected with the same material (which, however,
forms an unknown mixture of bacteria) there results no suc-
cinic acid, but carbonic acid, acetic acid, formic acid, pro-
pionic acid, and a little butyric acid.

According to Fitz's experiments, citrate of lime furnishes
large quantities of acetic acid, under the influence of small,
thin bacilli (from hay-water), while as bye-products we have
aethylic alcohol and succinic acid. — Mucic acid also is, ac-
cording to Schiitzenberger, readily split up into acetic acid,
carbonic acid, and hydrogen.

Finally, we may mention here the fermentation of quinate
of lime, which has been observed by Loew, from which, when
air is present, there results protocatechic acid ; but when
oxygen is absent, acetic acid and propionic acid.

Although the progress which has been made during Incomplete-

,, , , f° , ,. ,, , f f fa ness of these

the last few years, as regards the method of performing experiments
these experiments on fermentation, in that attention ^ fermenta-
has been paid to the purity of the organisms sown, is
very marked, we must accept with a certain reserve
all the decompositions which have been referred to in
the foregoing paragraphs, because in almost all the
experiments the purity of the cultivations is not abso-
lutely free from question. In order to obtain a really
trustworthy result, it is evidently not only necessary
to cultivate the fermentative agents pure, and to sterilise
the fermentescible substratum carefully, but it is also
well, after tbe termination of the fermentation, to examine
the remaining fluid with the aid of tbe recent bacteriologi-
cal methods in order to ascertain that no other bacteria
than those tbat were sown are present, and have taken part
in tbe decomposition observed. It is absolutely necessary
to require these precautions on account of tbe danger,
never completely avoidable, of tbe accidental entrance

* Koenig, Chem. Ber., vol. 14.

606 VITAL ACTIONS OF THE LOWER FUNGI.

of saprophytes. This test, however, has almost never

heen employed.

Fcrmenta- Thus on the whole we have very few certain facts as

pioyedTii the *° *ne m°de in which the decompositions are brought
preparation of about hy certain species of bacteria. Hence it is that

food. * . „

we are, as yet, very imperfectly informed as to many
of the most frequent fermentative processes which spon-
taneously occur, or are artificially set up in our surround-
ings, for example, in the preparation of food, in many
Fermentation manufactures, &c. Even as regards the cause, the
course, and the products of the fermentation of bread,
we know very little that is trustworthy. It is very pro-
bable that the rising of the leaven is not caused by a
pure yeast fermentation, for, especially in leaven,
bacteria are present in preponderating numbers. Ac-
cording to the more recent investigations of Chicandard,*
yeast does not play any part, or only a very secondary
one, in the fermentation of bread, and the true agent
seems to be rather a species of bacterium. Marcanot
also sees in the mobile bacteria the true cause of the
fermentation of bread, while BontrouxJ is of opinion
that in this process several kinds of organisms, varieties
of yeast, and bacteria play an active part. — It would be
very desirable to obtain information as to this daily
fermentative phenomenon by means of accurate experi-
ments made with the aid of the more recent bacterio-
logical methods. §

In some cases combinations of fermentations are em-
ployed in the preparation of nutrient materials, especially
in order to obtain the formation of aethylic alcohol by
means of yeast from materials which are not in reality
fermentescible, for example, from starch, dextrine, milk-

* Chicandard, Compt. rend., vols. 96, 97. t Marcano, ibid.

J Bontroux, ibid., vol. 97. — Moussette, ibid., vol. 96.

§ Duclaux has made minute investigations as to the bacteria which
grow in milk and in cheese, and which take part in the decompositions
which occur; he designates them under the generic name tyrothrix,
and distinguishes T. scaber, T. tenuis, T. filiformis, &c. — Unfortu-
nately the papers in which these results are given in detail (Annals de
rinstit. agron., and Duclaux's Chimie bioloyique} could not be obtained
in the libraries in Gottingen and Berlin, and only became known to the
author at too late a period to be utilised in this work.

FERMENTATION OF THE FATTY ACIDS. 607

sugar. Sack combined fermentations probably occur in
the preparation of cliicha from maize, as well as of the
Japanese kosi from rice (Marcano*) ; further, in the two
kinds of milk wine which have been already mentioned
on page 372 — koumiss and kephyr.

Kephyr is, without doubt, the most important of these pre-
parations as an article of diet.f The method ordinarily Native mode
employed in its preparation by the inhabitants of the of manufac-
Caucasus is very simple ; the fresh cow or goat milk is Ure*
collected in a flask, a small quantity of the kephyr bodies is
introduced, the flask is closed and placed, in summer in a
shady place and during the cooler part of the day in the sun,
in winter in the dwelling rooms, and frequently thoroughly
shaken. The drink is ready after one or two days; it is then
poured off ; over the remains of the kephyr bodies left in the
flask new milk is poured. — Elsewhere, two methods are
employed in its preparation. According to the first, the dry, Preparation
brownish kephyr bodies, which are sold in this condition, are from dry
placed for five or six hours in lukewarm water, till they swell kePnyrbodies-
up. They are then carefully washed, and introduced into
fresh milk, which is changed once or twice daily till the
kephyr bodies become of a pure white colour, and in fresh
milk rapidly rise to the surface (after twenty to thirty
minutes). On a table-spoonful of granules so prepared about
a litre of milk is then poured, and the whole introduced into
a flask which is allowed to stand open for five or six hours,
then tightly closed and kept at about 18° C., being shaken up
about every two hours. After eight to twenty-four hours the
fluid is passed through a fine sieve into another flask (this
must not be more than four-fifths full) ; it is then corked and
shaken from time to time. After twenty-four hours the so-
called one-day-old kephyr is obtained, which contains only
little carbonic acid and alcohol ; as a rule it is the two-day-old
which is drunk, and which, after standing at rest for some
time, divides into two layers— a lower, whey-like and trans-
parent ; and an upper, formed of extremely fine flakes of
casein ; when it is shaken up it has a cream-like consistence.
Three-day-old kephyr is still thinner and very sour. — What
remains after filtration through the sieve can be added to
fresh milk after being thoroughly washed with water.

The second and more simple method can be employed where Preparation
a good two or three-days-old kephyr is obtainable. Of this, j^J arctive

* Marcano, Compl. rend., vol. 95.

t After Krannhalls. — Kephyr was introduced into Germany at the
establishment of Dr. Stern in Kissingen.

608

VITAL ACTIONS OF THE LOWER FUNGI.

Chemical
composition
of kephyr.

one part is added to three or four parts of fresh cow milk, it
is then introduced into flasks and allowed to stand for about
forty-eight hours, being shaken from time to time. Of the
drink so prepared, from one-fifth to one-third is left behind
in the flask, as a ferment for new milk which is added to it. —
The temperature must, as a rule, be about 18° C. ; it is only
at the commencement that a higher temperature is desirable.
— The kephyr granules which are being employed must be
cleansed carefully from time to time, and broken down till
they are about the size of a pea. The cleansed granules can
then be dried on blotting paper in the sun or in the neighbour-
hood of an oven ; in the dry state they retain their power of
growth for a very long time — for several months, and even
years.

The chemical investigations have as yet added as little
knowledge as to the course of the kephyr fermentation
as have the cultivation experiments. It is certain that the
most important products of fermentation are sethylic alcohol,
lactic acid, and carbonic acid ; small quantities of glycerine,
succinic acid, acetic acid, and butyric acid are also formed.
The amount of lactic acid in prepared kephyr is usually about
1*5 per cent. ; the amount of alcohol 1° Tr. ; both have been
shown to arise only from the milk-sugar. During the first
twenty-four hours the greater proportion of the milk-sugar is
utilised for the formation of lactic acid, while during the
following days the formation of alcohol is greater. When
the temperature is high (25° to 30° C.) the lactic fermentation
is too greatly favoured as compared with the alcoholic fer-
mentation, and it is only at a definite low temperature that the
two fermentations follow a normal course. — The amount of
albumen in the milk is, according to the analyses as yet made,
apparently not altered in the kephyr fermentation ; but the
casein undergoes an alteration in that it becomes suspended in
the milk in extremely fine flakes, so that the whole fluid
assumes an almost cream-like consistence. It is probable that
the dietetic value of the preparation is largely due to this
alteration in form of the casein. Peptone cannot be demon-
strated.

(61). Putrefaction.

Putrefaction. Under the term putrefaction, or putrefactive fermenta-
tion, we understand the rapid and intense decomposition
of nitrogenous and chiefly albuminoid substances by
certain bacteria in which gaseous, foul-smelling products
are formed in large quantities.

PUTKEFACTION. 609

The material for this fermentation is, in the first Material,
place, furnished by the albuminous substances them-
selves ; these never seem to undergo the decompo-
sition directly, but first become converted into peptone ;
as, however, a peptonising ferment is usually pro-
duced, by putrefactive and many other bacteria, there is
practically only a difference as regards time between
the putrefaction of soluble and insoluble albuminous
materials ; by the addition of peptonising pancreatic
ferment the putrefactive process is, however, hastened.
Further, gelatinous materials, and materials which give
rise to gelatine, are liable to undergo putrefactive fer-
mentation ; then the peptones ; finally, some nitro-
genous bodies, which are, however, more removed from
the proteid materials in their composition and in their
characters, but which are closely allied to them in that
they must be looked on as components of the albuminous
molecule ; more especially leucine, perhaps also tyrosin,
indol, &c.

In accordance with our present views as to the com- Nature of the
position of the albuminoid bodies, and in accordance tion°m
with the analogies with the decomposition which these
bodies undergo as the result of the action of acids and
alkalies, we must, as a whole, assume that in the decom-
position of the albuminoid molecule as the result of
putrefaction, amido derivatives of the fatty acids (amido
acids) , nitrogenous bodies of the aromatic series, sulpho-
acids (taurin), and perhaps also peptone-like bodies
are formed. As a rule, however, the products which •
first appear are rapidly broken up further, so that, they
scarcely attract attention ; for example, the arnido acids
are broken up into ammonia and fatty acids, of which
the latter are still further decomposed according to the
formulae given above, usually with the liberation of
carbonic acid, hydrogen, and marsh gas. Thus, in the
case of leucine a fermentation has been found which
seems to take place according to the formula C5H10
NH2 COOH (leucine) +2 H20 = C4H9 COOH (valerianic
acid) + NH3 + C02 + 2 H2. Glycocol and other amido
acids probably also undergo a similar decomposition.

39

610 VITAL ACTIONS OF THE LOWER FUNGI.

In the case of tyrosin also we must assume that a
further rapid decomposition takes place, because it i&
only found in considerable quantities at the commence-
ment of putrefaction ; according to Nencki this fermenta-
tion can occur according to the formula : CCH4 OH

= CH (indol)

"

nr>rkTT fL • N
C2H3 NH2 COOH (ty rosin) =

-f C02-f H20 +H2. According to Baumann, in the
putrefaction of tyrosin, when the entrance of oxygen is
not completely hindered, hydroparacumaric acid, paroxy-
phenylacetic acid, paracresol, and phenol are formed in
that order ; in this decomposition paraethyl, phenol,
and paroxybenzoic acid probably form intermediate
stages, carbonic acid, water, and ammonia being set
free. Other observers have demonstrated the formation
of hydrocinnamic acid from tyrosine. — Among the tran-
sitory products we have also succinic acid, which breaks
up into carbonic acid and propionic acid, likewise phenyl-
amido-propionic acid, which furnishes phenyl acetic acid,
and phenylamidoacetic acid, which gives rise to small
quantities of amygdalic acid, along with other products
of decomposition.

Products. The following are the numerous bodies which arise in

putrefactive processes : carbonic acid, hydrogen, free
nitrogen, sulphuretted hydrogen, phosplmretted hydrogen ,
methane ; formic acid, acetic acid, butyric acid, valerianic
acid, palmitic acid ; acrylic acid, crotonic acid ; gly collie
acid, lactic acid, valerolactamic acid ; oxalic acid, succinic
acid ; leucin, glycocoll, glutaminic acid, aspartic acid,
amidostearic acid ; ammonia, carbonate of ammonia,
sulphide of ammonia ; numerous amine bases, propy-
lamine, trimethylamine, &c. ; indol, scatol-carbonic acid,
scatol ; tyrosin, and the bodies belonging to the aromatic
series which have been above mentioned as originating
from it ; finally, the ptomaines referred to on p. 569.

The number and multiplicity of these products lead
to the conclusion that their formation does not always
occur to the same extent in every putrefactive fermenta-
tion. As a matter of fact we by no means always find
all the products mentioned ; on the contrary, the decom-

PUTREFACTION. 611

position of the albuminous molecule runs its course in
a varying manner, and leads to the production, some-
times of these, sometimes of those, products in largest
amount. This varying course of putrefactive processes Varying ^
can be in part occasioned by differences in the fermen- putrefactive6
tescible material, in part, also, by differences in the processes.
external conditions ; but the cause of the greatest and
most important variations is differences in the kinds of
bacteria which set up putrefaction. According as one
or other species of bacteria, or a varying mixture of
them, gain the upper hand in the putrefying mixture
we have a qualitative or quantitative difference in the
nature of the products.

Since we have been able to employ the methods of Multiplicity
pure cultivation for the organisms which excite putre- agent^of ^
faction, we have good grounds for believing that we shall Putrefaction,
be able to obtain definite proof of the fact that various
kinds of bacteria are capable of splitting up albumen,
and, at the same time, obtain an insight into the mode
of action of each of these kinds. Even now we know
a large number of species of bacteria which can, in pure
cultivation, occasion a rapid decomposition of the albu-
minous molecule, with the formation of foul-smelling
gases, but the action of these is very various, whether
we look at the nature of the products, or at their quantity.
In the case of the majority of these products we require
a more accurate knowledge of their chemical nature ; in
the case of many it is only the development of foul-
smelling gases, the chemical composition of which is
not more accurately known, which leads us to assume
that a putrefactive decomposition of the albuminous
molecule has occurred. The following are examples of
these kinds of bacteria : —

Species of bacterium.

Bacillus putrificus coli

Bacillus saprogenes, I, II, III. [

Putrefactive products as yet
demonstrated .

peptone, ammonia, fatty acids,
tyrosine, phenol, indol, sca-
tol, &c. (see p. 377).

foul-smelling gases.

G12

VITAL ACTIONS OF THE LOWER FUNGI.

Species of bacterium.

Bacillus coprogenus foetidus
Proteus vulgaris, mirabilis,

Zenkeri
Bacillus pyogenes foetidus ...

Micrococcus foetidus

Miller's Bacillus (p. 375)

Bacillus fluorescens lique-

faciens (bacterium termo?)

Bacillus butyricus, Hueppe...

Bacillus ureae

Bacillus prodigiosus

Bacillus pyocyaneus

Bacillus fluorescens putidus

Bacillus janthinus

Various anaerobes

Bacteria from mud or the in-
testinal contents of rumi-
nants (Tappeiner)

Different
results of the
action of
different
putrefactive
organisms.

Putrefactive products as yet
demonstrated.

foul-smelling gases,
peptone, foul-smelling gases.

foul-smelling gases.

foul-smelling gases.

sulphuretted hydrogen, am-
monia.

peptone, volatile fatty acids,
green colouring matter.

peptone, leucin, tyrosine, am-
monia, substances with a
bitter taste.

trimethylamine.

trimethylamine.

peptone, ammonia.

trimethylamine.

peptone, ammonia.

foul-smelling gases.

carbonic acid, marsh gas, sul-
phuretted hydrogen, &c.

It must be further mentioned that Salkowski has
found very various quantities of indol and scatol in his
analyses of putrefying mixtures, and that he refers these
variations to differences in the prevailing kind of bacteria ;
Tappeiner's observation must also probably be interpreted
in the same manner. He has found that, in the paunch
of cattle, scatol only occurs, and not indol, which is
otherwise very widely distributed in the intestines of the
herbivora.

Hence we must come to the conclusion that numerous
kinds of bacteria are capable of splitting up albumen,
but that they are not all able to furnish representatives
of the various groups of putrefactive products in such
a complete manner as Bienstock's bacillus putrificus
coli, for example ; but that many can only break up
certain parts of the molecule, leaving considerable por-
tions unaltered. Hence we cannot attempt to form
general formula for the decomposition of albuminoid

PUTREFACTION. 613

materials as the result of putrefaction. We can only
employ definite chemical formulae for each kind of putre-
faction occasioned by a definite micro-organism.

The putrefaction which occurs spontaneously shows Spontaneous
very great differences, according to the bacteria which pl
are accidentally present, and according as the conditions
of existence are at the time more favourable for one
or other species. The kind of organisms which gain
the upper hand at the commencement of the process
depend on the concentration, the chemical composition,
the reaction, and the temperature of the putrescible
materials ; in the course of time, and under the influence
of gradually extending putrefaction, these external con-
ditions alter completely; from neutral bodies others can
arise which cause an acid reaction ; by the decomposition
chiefly of nitrogenous molecules and the formation of
ammonia the alkalinity of the material may be increased ;
the relation of the individual chemical materials alters,
because one kind is broken up to a greater extent than
another. Thereby the most favourable conditions of
existence are again provided for other kinds of bacteria ;
and thus the spontaneous putrefaction consists of a series
of decompositions, not as a rule following any definite
order, but dependent on individual conditions which
cannot be controlled, these decompositions being caused
by various different kinds of bacteria, and kinds which
act in the most various ways. At the commencement
of putrefaction we usually observe several kinds of micro-
cocci and also large bacilli; in the later stages we find
in addition masses of short bacteria; on the surface of
the mixture forms seem to predominate which were for-
merly described under the name of bacterium termo,
and of these it appears from plate cultivations that bacil-
lus fluorescens liquefaciens forms the largest numbers.
Nor must we forget that numerous forms of bacteria
which have no fermentative action, or which do not find
a suitable material for the development of their fermen-
tative activity, establish themselves in putrefying mix-
tures, though it is true that at a later period, when
energetic fermentation is present, the organisms which

614

VITAL ACTIONS OF THE LOWER FUNGI.

Influence of
course1 oftb

Pasteur'

play an active part in it usually hinder the development
of other forms. All these accompanying micro-organisms
must complicate the putrefactive process, in that the
specific products of their tissue change become mixed
with the products of the fermentation.

Oxygen exerts the greatest influence on the course of
the putrefactive process, [t has been long known that
true Putrefaction, with foul-smelling gaseous products,
occurs only when the amount of air is limited. When
air is freely admitted these odours are absent, and a
rapid and very complete oxidation of the putrescible
materials takes place, thip form of putrefaction being
therefore designated under the special name decay.
Pasteur was the first to indicate more clearly the differ-
ence between putrefaction in the presence of oxygen, and
putrefaction without oxygen; according to Pasteur, when
air is excluded, the oxygen contained in the fluid is, in
the first place, used up completely by certain micro-
organisms (monas crepusculum and bacterium termo).
As soon as the oxygen is removed these bacteria die, and
fall to the bottom of the vessel in the form of a deposit.
The true After this has occurred the true putrefactive bacteria

putrefactive . . ,

organisms are appear; they can only exist where oxygen is absent;

anaerobes. ^ey gej. Up ^ putrefactive fermentation, and absolutely
require the preparatory action of these aerobes. If, on
the other hand, the fluid is freely exposed to air, the
aerobic bacteria develop continuously at the surface and
form a scum, which at times falls to the bottom in
masses, but is constantly regenerated. This scum pre-
vents the access of the oxygen to the fluid, and thus it
is possible that vibriones, which can only live when
oxygen is absent, but which cause the fermentations, can
-develop in the fluid, as it were under the protection of
the bacterial cover. The somewhat complex fermentative
products thus formed serve as nutriment to the aerobes
at the surface, and the latter then break them up into
the simplest compounds, water, carbonic acid, ammonia,
and thus the products which are ordinarily characteristic
•of putrefaction are not found.

In this way Pasteur sought to explain the difference

PUTREFACTION. G15

between putrefaction in the presence and in the absence Putrefaction

f . i • , i i • , i e f also occurs in

of oxygen, in correspondence with his theory of fer- the presence
mentation based on the absence of this gas. This view of oxy»en-
is, however, evidently not quite correct. As the result
of more recent investigations, it has been shown
'beyond doubt that, as well in the presence as in the
•absence of oxygen, certain kinds of bacteria are able
to split up the albuminoid molecule and furnish the
products characteristic of putrefaction. Further also,
we have in the chemical processes which occur in putre-
faction a partial explanation of the influence of oxygen.

When oxygen is absent extensive reduction processes
occur, which, for the most part, arise directly in the pro-
cess of fermentation ; fatty acids are formed from oxy-
acids; marsh gas, sulphuretted hydrogen, sulphur (for
example in the beggiatoa) appear ; above all, however,
hydrogen is formed in the various fermentations. As is
evident from the formulae given above, hydrogen is processes
liberated in the fermentation of formic acid, lactic acid oxyg-en'i? a
(butyric acid fermentation), glycerinic acid, malic acid, present-
tartaric acid, erythrite, leucin, &c. ; this hydrogen must
at times lead to further reduction effects. Nitrates must
be converted by this hydrogen into nitrites, indigo blue
into indigo white, invert sugar into mannite ; sulphates
•can also probably be reduced by it. On the whole, how-
ever, the alteration of the fermentescible material and of
the products of fermentation, as the result of the action of
the hydrogen, is only slight, and it is characteristic of the
course of fermentation without oxygen that the true fer-
mentative products appear in the main in an unaltered
condition without having undergone further destruction
and oxidation ; and also we can understand that in this
process of putrefaction only those bacteria can exist
which are able to act without the presence of oxygen, so
long as they have fermentescible material at their
disposal.

The case is otherwise when there is free access of Role of the
oxygen. In this case the same hydrogen which in the hydrogen.
former instance only performed a secondary function,
probably now plays a much more important part.

616 VITAL ACTIONS OF THE LOWER FUNGI.

Hoppe-Seyler has tried to show that when oxygen is
present the nascent hydrogen breaks up the molecule of
oxygen and thus renders the latter active ; the nature of
the process heing that, as the hydrogen is gradually
formed, two atoms of it constantly take up one atom of
the oxygen molecule and thus form water, while the
other atom of oxygen is capable in the free state of
causing the most powerful oxidations. Hoppe-Seyler*
has recently shown that hydrogen arising in other ways
also possesses this power of rendering oxygen active ;
thus it is possible to set up energetic oxidation pro-
cesses by means of palladium hydrate by gradual dis-
sociation of the hydrogen in the presence of oxygen ;
and the action of phosphorus on oxygen has a similar
explanation.

On this view we can understand how it is that in the
presence of oxygen putrefaction runs such a completely

Inodorous different course than when oxygen is excluded. It is
not only that the true reduction products, such as hydro-
gen, or sulphuretted hydrogen, do not appear, having
undergone oxidation, but also that a number of other
substances, which at the ordinary temperatures are quite
resistant to the closed oxygen molecule, are attacked
by the active oxygen and converted into the most simple
compounds. Thus the destruction of the putrescible
material occurs in as complete a manner as when it is
broken up in the living animal body, or in that of
bacteria which normally oxidise the nutrient materials
when oxygen is present. Further, it is not uncommon
that, both on and under the surface of the fluid, bacteria —
or, when the circumstances are favourable, yeast, or
mould fungi — obtain their nutriment from the products
of the fermentation and burn these up to the most
simple compounds ; and we must regard it as at present
undetermined whether the products of putrefaction can be
more frequently and in larger quantities destroyed in
this way, or as the result of the nascent hydrogen, and
its action on the oxygen.

Spontaneous In our normal surroundings, both putrefaction and

putrefaction * Zdtsckr.f.physiol. Chemie, ii., 22. — See also Baumann, ibid., v. 244.

and decay.

PUTREFACTION. 617

decay constantly occur. Where fluids putrefy for a long
time — in cesspools, canals, gutters, &c. — fermentation
and putrefaction ordinarily occur at first as the result
of the action of aerobic hacteria ; as the oxygen is
gradually used up, and as carbonic acid, hydrogen, and
other gases fill the fluid, a condition arises so favourable
for anaerobic bacteria as can scarcely ever be procured
by artificial means in pure cultivations. The anaerobes
then continue the putrefactive process, and more espe-
cially occasion the formation of large quantities of
stinking gases ; and, in addition to these putrefactive
anaerobes, other bacteria, which stand in no sort of
relation to the putrefactive process itself, such as the
bacilli of malignant oedema and of tetanus, utilise the
favourable conditions of complete exclusion of oxygen,
multiply, and form spores.

A true decay, that is to say a putrefaction without Decay in the
the development of odorous gases and of reduction pro- sc
ducts, implies an extremely intimate contact of the
putrescible material with the air. The most favourable
conditions for this process seem to exist in soil which is
very porous, and is moistened from time to time ; under
such circumstances mineralisation of organic substances
occurs in such a complete manner that in a short time
neither ammonia nor sulphuretted hydrogen, nor more
complex carbon compounds are present, but on the con-
trary only nitrates, sulphates, and carbonic acid. For
further remarks as to nitrification see the chapter on
"Soil." — We very frequently meet with a mixture of
putrefaction and decay in dead organic materials. In
the upper layers of a fluid, or on the surface of a dead
body, decay can occur, while in the deeper layers putre-
factive processes of such extent and intensity take place
that the products of true putrefaction appear side by
side with the products of decay.

In the decomposition in the soil we frequently observe Mouldiness
products which can not as yet be satisfactorily defined; (vcr
these are more especially seen in the destruction of portions
of plants which chiefly consist of cellulose. In this case
there is a formation of humin substances, and when oxygen

618 VITAL ACTIONS OF THE LOWER FUNGI.

is absent there is a plentiful formation of marsh gas in
marshes. This decomposition of vegetable substances, poor
in nitrogen, is specially designated by the term mouldiness
(Vermoderung) ; but the chemical meaning of this term is not
yet quite clear. The term decay ( Venvesung) is also at present
employed for several different processes ; thus Nageli uses it
for the destruction of organic substances by mould fungi.
In this, however, we have no really marked fermentative
action, but only a gradual consumption of the nutrient
materials, and hence it is better to restrict the term to putre-
faction in the presence of oxygen in which — when the con-
centration and reaction of the medium are favourable — the
mould fungi naturally help in the complete decomposition
of the material. Under special circumstances where suitable
bacteria, or a fermentescible material, or other conditions
for the fermentative processes are absent, the consumption of
the organic substances by mould, yeast, and fission fungi
plays the chief part ; the destruction must then, however, go
on correspondingly slowly, and furnish the ordinary products
of tissue change of the lower fungi. It would be incorrect
to reckon such a process among the processes of fermentation
or putrefaction.

(e). Acetic Fermentation.

Acetic By acetic fermentation we mean the process by which

fermentation, gethylic alcohol is converted into acetic acid, and which
is expressed by the formula, CH3, CH2, OH (asthylic

Material and alcohol) +02 = CH3 COOH (acetic acid)+ H20. Ac-
cording to Nageli methylic alcohol is oxidised to formic
acid in a similar manner. The oxygen is taken up to
a very much less degree when alcohol is exposed to
the air, and spread out over a large surface on filtered
paper, wood shavings, &c. ; it occurs to a greater extent
when spongy platinum, charcoal, and similar porous

Fermentative bodies aid the conveyance of the oxygen. It is par-
ticularly energetic, however, when the development
of a definite fungus occurs in the alcoholic material,
especially when it is spread over a large surface. As to
the morphological characters of this fungus see p.
389. Along with it there are usually found other
fungi ; saccharomyces mycoderma often develops at the
commencement in greatest numbers, so that this fungus

ACETIC FERMENTATION. 619

was formerly looked on as the exciting agent of the
acetic fermentation. According to Nageli, however,
this form of yeast only prepares the soil for the acetic
fungus hy using up the fruit acids when they are pre-
sent in large amount in the fermentescible material, and
the presence of which would hinder the development of
the bacteria ; in this way it neutralises the medium.
But this explanation of the peculiar concurrence of
these two species of fungi, which is so often observed,
is not completely satisfactory, because the acetic
bacterium can bear the presence of acetic acid in the
nutrient fluid in much larger amount than other
bacteria.

The development of the acetic fungus only occurs conditions of
when the ordinary nutrient materials, nitrogenous sub- fermentation,
stances, and salts, are present. The fermentescible
material (the alcohol) must not be present in too great
concentration (at most 10 per cent.). The develop-
ment of the acetic fungus occurs best when a certain
quantity of acetic acid (1 to 2 per cent.) is already pre-
sent. The formation of acetic acid ceases below 10° C.
and above 35° C. ; the optimum lies between 20° and
30° C. ; by heating the fermenting fluid to 60° C. for
twenty minutes, the fermentative action is permanently
stopped unless new bacteria obtain access to it. As to
the other products which appear in the fermenting mix-
ture nothing is known ; according to Nageli, the acetic
fungus forms extremely minute quantities of carbonic
acid and water.

According to the few certain observations which have been Doubtful rule
made as to the acetic fermentation, this process seems to be ?gf^ ^the*1"
very different from that of the other fermentations. Marked acetic fer-
decomposition of the alcohol molecule and marked formation mentation,
of carbonic acid does not occur ; the formation of acetic acid
runs its course much less violently than the other fermenta-
tive processes ; the same effect is obtained by spongy
platinum and by charcoal. All this has led Pasteur to the
view that the formation of acetic acid is not really a physio-
logical action of the fungus, but that the organisms only act
in a similar manner as spongy platinum, as carriers of oxygen.
Mayer has, however, pointed out, as against this view, that
the optimum of the action of the acetic fungus is quite

620 VITAL ACTIONS OF THE LOWER FUNGI.

different to that where the acetic acid is formed by means
of spongy platinum; the latter process is increased by an
elevation of temperature which is destructive to the fungus.
Nevertheless, it is evident that the action as oxygen-carriers
must be bound up with a large number of intact fungus-cells,
and that this action must, to a certain extent, run" parallel with
the active development of the fungus. And further, the fact
that specific forms are found in association with the formation
of acetic acid can not alter Pasteur's view; for the con-
ditions of existence of the fungi which take part in the
formation of acetic acid are so peculiar both as regards the
amount of alcohol and the amount of acetic acid in the medium,
that only few forms can enter into concurrence with them.
Whether, however, as a matter of fact, only one or several
forms are involved in the action must be determined by
further pure cultivations.

If, on the other hand, the formation of acetic acid is a
physiological act of certain fungi, we would expect that the
multiplication of the fungi would be intimately connected
with their function, that other products of tissue change
would also be formed, that, at all events, there must be in
part a further oxidation of the acetic acid. And further, it
is a question whether we ought in reality to look on the for-
mation of acetic acid as a fermentative process, or whether
we must not simply regard it in this way that the fungi,
among other nutrient materials, also take up alcohol, when it
is present in particularly large amount, and oxidise it only to
acetic acid. In the latter case Pasteur's carrying of the
oxygen takes place in the cells ; the alcohol acts as nutrient
material, which, when present in smaller quantity in the
nutrient mixture, is destroyed and burned up by very various
kinds of fungi ; which, however, when in a more concentrated
form only permits the growth of a few fungi, and is then no
longer burned up to the usual end products. This oxidation
of the alcohol can only be designated as fermentation in the
ordinary acceptation of the term, when it has been demon-
strated that relatively very large quantities of the material
can be acted on in a short time, that almost the whole of the
ferment escible material undergoes this incomplete oxidation,
and that this metamorphosis of the material is sufficiently
different from the ordinary physiological processes to be
looked on as a special function, as compared with the as-
similatory and destructive tissue change. — The solution of
these questions must be given by further investigations. If,
in reality, we have to do with a fermentation, then the whole
process of the acetic fermentation can be best understood on
Nageli's theory, to be mentioned immediately.

CHANGES IN FERMENTATION. 621

However different the chemical process is in each of General view
the fermentations described, we can find some general £ai process^
points of resemblance in all the true fermentations, fermentation.
We everywhere observe a marked splitting up of the
fermentescible molecule, and an extensive re-arrange-
ment of the atoms. In all cases carbonic acid is formed,
and for this it is evident that new combinations between
carbon and oxygen are necessary, and these are rendered
possible by the solution of combinations between oxygen
and hydrogen, carbon and hydrogen, carbon and carbon.*

In the fermentation of formic acid H — Cx^ TT Wandering of

V — -tL the oxygen

the union of the oxygen and hydrogen atoms in the atom*
hydroxyl group, and also that of the hydrogen and
carbon atoms, is broken up. The liberated hand of the
oxygen atom unites with the hand of the carbon atom
liberated at the same time ; the two hydrogen atoms
which are freed unite with one another, and thus C02
and H2 are formed. In a similar manner, in all fermen-
tations there occurs a wandering of the oxygen atom
from the hydrogen to the carbon ; while, on the other
hand, by the separation of the C — H and C — C union
room is procured for the new attachment of the oxygen
to the carbon. In short, the group carboxyl is formed
while, on the other hand, reducing atomic groups, H —
H or C — H compounds, appear. In the whole move-
ment stronger affinities are grouped together, and
energy becomes free. Nevertheless, the wandering of
the oxygen atom which leads to the breaking up of
the molecule only occurs when the molecule is not
too large in relation to the number of the displaceable
oxygen atoms. If, as in the case of many benzole
derivatives, and in the higher fatty acids, numerous
carbon atoms are united with each other, wrhile only
one C — H group is present which can form carboxyl,
no such wandering occurs in a molecule; on the
other hand, this wandering is possible when several 0
atoms can enter into new C combinations, as in the fer-

* Hoppe-Seyler, Physiolog. Ckem., p, 124.— Arch. f. d. ges. physiol,
vol. xii. 1.

622 VITAL ACTIONS OF THE LOWEK FUNGI. -

mentation of the glucoses, where three carboxyl com-
binations are present in the six C atoms, and lead to
the breaking up of the relatively large molecule. For the
same reason fermentation of acetic acid is very difficult,
and of propionic acid still more difficult ; for here, as in
the case of formic acid, there is only one 0 atom which
can be utilised for the formation of carboxyl, while the
molecule itself is much larger. On the other hand, fer-
mentation can occur more readily in the oxy-acids
(glycollic acid, lactic acid, &c.), because in these there
exists a second hydroxyl group, and thus a second dis-
placeable 0 atom. Accordingly, the following sub-
stances are not at all capable of fermentation : carbu-
retted hydrogen, amines which do not contain any oxygen ;
further, the large molecules of the higher fatty acids,
and of the benzole derivatives which are poor in oxygen
(the latter only in regard to the benzole portion, while,
naturally, in the side groups, splitting up and wander-
ing of oxygen can occur). On the other hand the fol-
lowing, among other substances, must be capable of
fermentation : the higher alcohols, the lower uni-basic
fatty acids, up to propionic acid, the oxy-acids, and the
multi-basic acids of the fatty series, the carbo-hydrates,
and the albuminoid materials.

The dccompo- Hence without extensive displacement of the atoms,
sition of the no fermentation is conceivable, and it is by this in-
this case is tense alteration of the fermentescible molecules that
th?arcet^onfro0fm the true fermentations are chiefly distinguished from
enzymes. fae hydrolytic decompositions caused by isolated fer-
ments. All fermentations are direct results of the func-
tional activity of micro-organisms, and it is not only
absolutely certain, from the experiments previously
described, that fermentation never occurs without living
organisms, but we must also free ourselves from the
idea that the fermentative action results from the pro-
duction of a ferment which cannot be separated from
the micro-organism without interfering with its life.
The intimate process of fermentation shows so much
that is different from that of the action of enzymes, and
shows, on the other hand, such an intimate connection

CHANGES IN FERMENTATION. 623

with the other direct vital actions of the micro-organisms, The fermenta-
that we must of necessity look on the fermentation as a physiological

physiological function of the living cells. act of living

L v organisms.

We must further assume that the mode in which
fermentescible substances are split up differs very much
according to the species of micro-organism which excites
it. It is true that the former view, that one organism
exclusively possesses the power of setting up a definite
fermentation, is not confirmed by more recent investiga-
tions, but the functional action of the individual fungi
which set up fermentation is none the less a specific
one, and the same fungus always splits up the same
material in the same manner. This specific property Specific

1 . /, ., -, fermentative

also remains constant for the same species, and is activity of the

developed whenever the other conditions suitable for

the fermentation in question, such as material, tempera- bacteria.

ture, &c., are present. It is only as the result of Constancy of

certain noxious influences which will be discussed under

the conditions of death of the lower fungi that there can

be a loss or a weakening of this property of exciting

fermentation. (Facts of this kind have, at any rate, Weakening of

been observed by Fitz in the case of two butyric acid offsetting'3''

fungi.) But these attenuated bacteria cannot occasion fermentation.

some other fermentation ; on the contrary, they retain

their specific character, and they have only lost, as the

result of noxious influences, that peculiar specific physio-

logical function which is expressed in the excitation of

fermentation.

Although it is thus clear that we must look on
the fermentations as the physiological functional acts
of certain micro-organisms, there still remains great
uncertainty with regard to the mode in which we should
define this function, and with regard to its relation to
the other vital actions of the organisms.

In the organisms which are capable of setting up The tissue
fermentation tissue change can run its course in various £na££e. ^S1^
ways ; either the organisms are present in a nutrient, excite fermen-
but not fermentescible, medium (such as yeast in a
solution of milk-sugar), and in that case they do not
behave like organisms which can cause fermentation ;

624 VITAL ACTIONS OF THE LOWER FUNGI.

they assimilate their nutriment, grow and multiply,
break up the nutriment in their protoplasm, and taking
up oxygen form the products of tissue change formerly
described. Or oxygen only may be wanting in the
medium ; in that case the intramolecular respiration,
with its insignificant destructive tissue change, can for
some time maintain the life of the organisms. Or, in
the third place, a fermentescible material, suitable for
the organism in question, is present ; in that case
extensive decomposition of the material occurs, along
with active multiplication of the organisms ; this takes
place as regards the majority of organisms in every case
where the other conditions of life are favourable, in the
case of some (bacillus butyricus) it only occurs so long
as oxygen is at the same time absent.

The fermenta- The splitting up of the material, as the result of
tiyp action, fermentation, differs in many respects from the ordinary
tissue change. In the fermentation very much larger
quantities of material are acted on than are otherwise
necessary for the nourishment of the same number of
organisms. Further, the decomposition is a relatively
incomplete one ; in the respiratory tissue change the
nutrient substances are oxidised to simple compounds,
but in the fermentation the materials of the nutrient
medium remain, for the most part, in the form of com-
plex molecules, and it is only some of the more simple
groups that are broken up. Finally, in the fermenta-
tions the oxygen does not take an important part in the
breaking up of the materials, and more especially in
their conversion into the end products, as is the case in
respiration, but the whole decomposition often takes
place without any aid from oxygen, which only acts
secondarily and then causes oxidation.

In correspondence with these differences between the
ordinary tissue change and fermentation we have the
fact that many chemical materials act as nutriment
without being able to act as fermentescible materials,
and vice versd ; thus formic acid cannot serve as nutri-
ment but is broken up by fermentation, while, on the
other hand, the benzole derivatives and the higher fatty

CHANGES IN FERMENTATION. 625

acids resist fermentation, but are to a certain extent
good nutrient media.

The splitting up of the fermentescible substances never
forms the only physiological act of the organisms which
take part in it. It is evident that nutrition, growth, and
multiplication of the cells must go on at the same time,
and for this purpose the fermentescible materials do not,
as a rule, suffice, but salts, nitrogenous substances, and
at times also carbon substances, must also be at the
disposition of the fungi; when oxygen is excluded, the
presence of a particularly good nitrogenous nutrient
material is an absolute necessity for continued growth.
Further, the protoplasm, as the result of its action, must
always be to a certain extent used up, and thus the pro-
ducts of the destructive tissue change must appear, only,
in this case, the want of oxygen must bring about a
conformity of these products with those of the intra-
molecular respiration. It is for the progress of this
assimilating and destructive tissue change that the
necessary energy is obtained as the result of the fermen-
tation, although the sum of the material which is directly
utilised for this tissue change appears to be very small in
relation to the amount of fermentescible substance which
is broken up; according to Pasteur, the amount of the
sugar employed for nourishment, for example in an
energetic fermentation of sugar by means of yeast,
amounts only to 1 per cent, of the fermented mass.

As, in this way, the fermentative processes, up to a Is the fer-
certain point, go on alongside of the ordinary tissue materS? '

change, the further question arises whether it is neces- Broken up in

the cells r
sary for the occurrence of the fermentations that the

fermentescible material, like the nutrient material, must
not only come in immediate contact, but also enter in a
loose combination with the protoplasm, and must pass
into the interior of the cells, or whether the decomposi-
tion can take place outside the cells, and whether less
intimate contact of the protoplasm with the fermen-
tescible materials is sufficient for their decomposition?
According to experiments made by Cochin* it can be

* Cochin, Compt. rend , vol. 96.

40

626 VITAL ACTIONS OP THE LOWER FUNGI.

demonstrated that a part of the sugar from a saccharine
Solution in which yeast kept without oxygen is sown,
passes into the yeast cells and is there rapidly broken up ;
hut this only takes place with regard to a small fraction
of the sugar, and it does not occur in every yeast capable
of setting up fermentation. Hence the question as
regards the seat of the decomposition cannot as yet be
decided with certainty ; the great quantity of the material
broken up in a short space of time leads at any rate to-
the presumption that in fermentation a chemical combi-
nation between the protoplasm and fermentescible mate-
rials does not occur, but that that process is limited to the
ordinary nutritive and respiratory processes of the cells.
Nageli's Nageli has in fact put forward some very definite reasons
fermentation. f°r believing that fermentescible molecules lying outside
the cells (but it is true in their immediate neighbour-
hood) can be broken up by the movements in the proto-
plasm. This is shown, for example, in the formation of
acetic ether, which frequently accompanies the alcoholic
fermentation; acetic ether is not formed when acetic
acid is present in the fermenting mixture ; acetic acid
and alcohol must, on the contrary, meet in the nascent
state; if both were produced by the same organisms it
would be conceivable that they arose and combined
within the cells; but the alcohol is formed by yeast cells,
the acetic acid by bacteria, and thus their combination is
only possible if both the components arise outside the
cells. Nageli also observed that bacteria were able to
reduce and decolourise litmus colouring-matter, although
it could be shown that the colouring material could not
penetrate into the living plasma of the cells. Further,
numerous observations indicate that the alcoholic-
fermentation which occurs in the interior of uninjured
fruits is brought about by yeast cells, which have their
seat on the skin ; lastly, Nageli explains the fact that in
a sugar solution containing large numbers of yeast cells
bacteria which may have been present gradually die, by
supposing that the movements which are communicated
from the plasma of the yeast cells to the sugar molecule
ultimately pass on to the bacteria and thus weaken these

THE PARASITIC EXISTENCE OF THE LOWER FUNGI. 627

organisms, which require another kind of movement.
This fact can be utilised for obtaining, to some extent,
pure cultivations of yeast and of other fermentative
organisms.

Nevertheless, the observations made by Na'geli do not
lead us to any certain conclusion as to the occurrence of
the fermentative action. With regard to the formation
of acetic ether, it is always conceivable that the same
bacteria produce both components, because we know that
the formation of alcohol is not limited to the yeast fungi,
and that glycerine, for example — a body always present
in fermentation by yeast — is split up, according to Fitz's
experiments, by bacteria with the formation of alcohol
and acetic acid. Objections may also be made to the
other facts brought forward by Niigeli, but, on the whole,
Nageli's view appears, at any rate for the present, to be
the best grounded, and hence the most probable, hypo-
thesis as to the act of fermentation. According to him
the fermentative act occurs in this way, that as the result
of the intramolecular activity in the protoplasm intense
conditions of movement are brought about, and that, on
the other hand, chemical molecules are present outside
the cells, which are set into active movement as the
result of these motions, so that the breaking up of the
molecule results. Those organisms are not capable of
setting up fermentation, in the plasma of which unsuit-
able and insufficient movements arise; only those
chemical substances can be broken up by the fermenta-
tion to which the movements can be readily communi-
cated.

8. The Parasitic Existence of the Lower Fungi.

The extension of the vital activity of the lower fungi Parasitism^

and symbiosis.

which is of the greatest importance to us, is that they
can under certain circumstances grow as parasites on or
in the higher living organisms. It does not of necessity
follow that injury to the host is the consequence of such

628 VITAL ACTIONS OF THE LOWER FUNGI.

a parasitismus ; on the contrary, there are certain para-
sites which can live in a plant or an animal for a long
time without in any way influencing its normal exist-
ence, and indeed in many cases the parasitismus can form
an advantageous symbiosis for the host, as, for example,
in the lichens, which consist of a combination of algre
and fungi, in which the chlorophyl-bearing algae pro-
vide carbon compounds which can be utilised by the
fungus, while the latter takes up mineral nutrient
materials from the substratum, and thus supplies them
for the common nourishment.

As a rule, however, the advent of parasites, and more
especially of the parasitic fungi, is accompanied by more
or less severe injury to the organisms which they attack,
A number of the most devastating diseases of plants,
animals, and man, have been proved with complete cer-
tainty to be due to parasitic fungi, and our chief motive
and real aim in studying the morphology and biology of
the lower fungi is the fact that they can excite disease.
Classification Among the large number of the fungi which are
parasitic capable of leading a parasitic life, we notice, when we
fungi. study them accurately, differences as regards the mode

of the parasitismus which render it easier to understand
this peculiar phenomenon. Many of the parasitic fungi
are only able to lead this kind of existence, and these
can carry on their vital functions, either not at all, or
only in a very limited manner, on dead substrata ; other
fungi, on the contrary, also flourish as saprophytes, and
their parasitic existence is in fact only a continuous ex-
tension of the wide limits within which they can carry
on their life and action.

De Bary has sharply defined these differences, and has
based on them the following classification of the parasitic
fungi : —

Obligatory !• Obligatory parasites. These require a parasitic

parasites. jjfe jn or(jer to attain their full development. They may
be divided into two classes, namely, (a) Strictly obligatory
parasites, which only occur in nature as parasites, and
can be cultivated on dead substrata only under con-
ditions artificially produced in the laboratory ; and (b)

MOULD FUNGI AS EXCITING AGENTS OF DISEASE. 629

Facultative saprophytes, which as a rule complete their
cycle of development as parasites, but which can exist
under certain circumstances as saprophytes, and can pass
through some portion of their developmental cycle as
such.

2. Facultative parasites. These are species which Facultative
usually grow as saprophytes, but which, however, at

times find the conditions necessary for their existence in
living organisms, and can then multiply there.

3. Obligatory saprophytes, which cannot obtain any
foothold in the living vegetable or animal organism, but
can only grow on dead substrata.

The mould, yeast, and fission fungi behave so differently in
their roles as exciting agents of disease that they must be dis-
cussed separately. It is not the purpose of the present work
to give an accurate description of the parasitic diseases
caused by the mould fungi ; they will only be noticed in so
far as they furnish facts for some general conclusions. For
a more detailed description of the diseases of plants we must
refer to the works of de Bary, Hartig, and Frank.*

The natural mode of origin and spread of the diseases
caused by the bacteria will be discussed in detail in the
sixth and seventh chapters, while in this place we shall only
speak of the action and fate of bacteria which have already
penetrated into the body.

A. The Mould Fungi as Exciting Agents of Disease, (a) Parasitic

mould fungi.

The mould fungi are dangerous chiefly to the higher Mould fungi

i mi 11 i • XT j.- r ii which attack

plants. They are able to spread in the tissue of the plants,
plant, their germinating tubes and mycelial threads
penetrating into natural openings or through accidental
injuries of the epidermis, and then running between the
cells ; they frequently also bore through the walls of the
cells, and in that case have probably the power of
secreting a ferment which dissolves the cellulose.

The mode of action of the parasitic moulds is very Mode of

penetration

* De Bary, Vgl Morph. u. Biol. der Pilze, Leipzig, 1884, P. 384, ff.— and action.
Hartig, Lehrb. d. Baumkrankheiten — Vortruge im iirztl. ver. zu Miinchen,
1881. — Frank, Die Pfankenkrankheiten , Schenk's Ilandb. d. Botanik.
Breslau.

630 VITAL ACTIONS OF THE LOWER FUNGI.

various. At times they gradually destroy the whole of
the surrounding tissue, so that a mass of fungi, con-
sisting of mycelium and spores, occupies the place of the
original vegetable substances (ustilagineae, exoascus) ;
or alterations of a more local character arise, for ex-
ample, marked growth of the parenchyma, which leads
to all sorts of swellings and alterations in form (chytri-
diaceae, cystopus, &c.) ; or, finally, local alterations are
less noticeable, but instead a gradual degeneration of the
surrounding tissue occurs, which shows itself in dis-
colouration and browning of the cells attacked. In by
far the greatest number of cases the infection leads to
death of the plant, or to death and degeneration of the
fruit.

individual Among the large number of mould fungi there are rela-

ofthe p°ant°n ^ve^J ^ew species which possess this pathogenic power,
and we must assume that these species are provided with
particularly powerful means of penetrating the cell mem-
brane. Further, each of the pathogenic forms can only
attack one or a few species of plants, and among plants
which are apparently similar there are often only a few
individuals which are specially predisposed to the action
of the parasitic fungus. Minute differences in the
structure of the epidermis and of the cell walls, slight
variations in the chemical composition of the cell juice,
greater or less energy of growth and of tissue change,
are the conditions to which must be referred the con-
nection between certain parasitic fungi and certain
plants, the immunity of other plants, and, in short, the
individual predisposition to the infective diseases. The
epidermis of the plants seems to oppose an especially
great resistance against the fungi, and hence infection
can often only occur while the parts attacked are in a
young condition and still possess a delicate skin. Thus
the ustilaginese and peronospora inf. only attack young
plants or young seed ; hypoderma macrosporon only
penetrates into young pine cones. An injury of the
epidermis is often requisite to enable the mycelium
threads to penetrate it ; species of fumago only develop
on parts which are attacked by aphis ; in the case of

MOULD FUNGI AS EXCITING AGENTS OF DISEASE. 631

a species of nectria, which occasions the so-called cancer
of the pine hark, the necessary condition for the pene-
tration of the germinating tube is only furnished where
the bark has been eroded by moths ; the spores of
trametes pini sprout only on freshly broken surfaces of
branches, and from that point send their mycelial threads
into the wood. Frequently also it is only certain parts
of the plants which are suitable for the attack and
development of the fungi. Thus claviceps attacks
the flowers, exoascus the fruit, and byssothecium the
roots of the plants which are infected by these fungi.
De Bary gives an interesting example in the parasite
of the white rust of cresses, cystopus candidus, the
germinating tube of which can only develop in the
cotyledons, and can hence only infect those plants
which have just formed cotyledons at the time at
which the spores are being distributed and are ger-
minating.

While these peculiarities in the spread of the parasitic Seasonal and
diseases of plants may be satisfactorily explained by

differences in individual predisposition, we often observe distribution

. i f i 1-1 , -i f i °f epidemics

another series of phenomena which cannot be referred Of plants.
to the same cause. For instance, we often see in par-
ticular localities an epidemic spread of a parasitic
disease, while in other places plants of the same species
are only attacked in a sporadic manner; and in like
manner there are years in which the disease only
spreads to a slight degree, while at other times severe
epidemics occur in the same places.

These differences have their explanation in part in
•certain external • influences which vary with locality and
season, and which form the so-called local and seasonal
predisposition. A factor belonging to this class which
favours most of the infections caused by mould fungi is,
for example, a continuous and marked degree of moisture
in the air and in the soil, which of itself permits the
sprouting of the fungus spores. The ustilagineae,
claviceps, and many others, require such a continuous
moisture ; peziza willk., which occasions the cancer of
larches, only forms fruit-bearing hyphae when the air is

632 .VITAL ACTIONS OF THE LOWER FUNGI.

Factors which moist. The duration of the period of moisture is often

influence the ., . . ., . -, « ,,. .

spread. the important point ; thus epidemics 01 rosemma quer-

cina develop only when there is continuous rain ; the fruit
carriers of hypoderma macrosp. swell up and burst only
when rain has lasted for several days. At times also
the temperature must be specially favourable for the
sprouting of the spores, and they can only cause infec-
tion when suitable temperature and suitable moisture
happen to be present together. — The conditions for a
successful infection are still further complicated, in that
the above-mentioned factors which predispose to the
penetration of the fungus mycelium into the plant must
coincide with a certain stage of development of the
fungus, and with external conditions which are favour-
able to this development. A moist warm season is
often a predisposing factor which favours the growth of
the parasite when young plants are present, or when, at
the same time, insects have caused injuries of the
epidermis, or when, as the result of storm, &c., fresh
fractures of the branches have been produced. If these
predisposing factors are absent during the moist period,
or if the latter occurs when the plants in question are
older and provided with firmer epidermis, no infection
occurs. — Here and there other more remote factors,
which often seem to be a matter of chance, play a part
in the development, and more especially in the epidemic
spread of the parasitic diseases of plants. Thus the
development of the uredineae depends upon the condition
of their second host, which they require as the result of
their alternation of generation, and if the barberry
bushes are accidentally or intentionally removed the
rust of grain ceases ; in many species of fungi suitable
means of transport must aid the spread of the spores,
as in the case of phytophtora fagi, where men and
animals in passing transport the spores. Lastly, in
some cases where infection can only occur in the
immediate neighbourhood from the further spread of
the mycelium, everything depends on the grouping of
the plants which can be attacked ; it is only when these
occur in close contact with each other that an epidemic

MOULD FUNGI AS EXCITING AGENTS OF DISEASE. 638

spread can take place, while the latter is impossible as
soon as other species of plants, which are not liable to
the infection, are mixed with the individuals of the kind
that are threatened. — It is evident that by taking into
consideration all these numerous factors which exercise
an influence on the occurrence of epidemics, the rise
and fall of the parasitic diseases of plants can be
explained, and that at the same time these observations,
which can be made on plants with great certainty, must
be of great advantage in enabling us to understand the
epidemics of animals and man with which they offer
numerous analogies.

Among animals it is chiefly the invertebrata, and, Mould fungi
among these, the insects, which are attacked by para- on animals!
sitic mould fungi. The infection always occurs by the
penetration of the rnycelial threads into the external
uninjured skin ; in the case of empusa radicans it has
been demonstrated, as the result of experiments, that
infection never occurs from the intestine. In some In insects,
cases the fungus may enter almost anywhere; for ex-
ample, laboulbenia can penetrate through the back,
head, legs, or wings of flies. In other cases the place of
entrance is limited ; empusa muscae, for example, can
only enter at the abdomen of the fly, and in the case of
isuritB the infection of the caterpillars occurs through the
stigmata of the tracheae. — In some cases the parasitic
fungi cause very little inconvenience to their host ; thus
laboulbenia muscse may exert no injurious action, but
the insects attacked usually die. The mycelium threads,
when they have penetrated into the body, grow through
the muscle and fatty tissue, and usually give off conidia
in the blood, which grow to form an extensive my-
celium ; during this process there is an almost entire
consumption of the structures of the animal attacked.
Such an energetic growth is only conceivable when the
nutrient conditions which the animal body offers are
particularly favourable to the fungus, when the animal
cells assimilate with very little energy, and when there
is a more or less complete absence of reaction. These
conditions appear to be present in the insects which are

634

VITAL ACTIONS OF THE LOWER FUNGI.

In fish and
Mrds.

In man.

attacked. Here, however, we can also recognise certain
predisposing factors ; thus it has been observed that
botrytis bassiana does not attack all silk-worms equally,
but chiefly young individuals, and more especially those
which are in a weak state as the result of imperfect
nourishment, &c. It is only by careful selection in the
culture of the silk-worms that this disease can be
combated.

An infection by saprolegnia has been observed in
fish ; the fungus occasions, in the first place and very
gradually, a disturbance of the function of the skin, and
an affection of the gills, and, according to de Bary, the
disease develops only in fish which are already ill from
other causes. In the case of birds, mould fungi occur
comparatively frequently in the respiratory organs;
Bollinger* and Schiitz (see p. 124) have shown that
these fungi do not occur secondarily in organs pre-
viously diseased, but that they are the primary causes of
the disease ; they develop partly in the trachea and in
the bronchi, partly also in the tissue of the lungs and
in the cavities of the lung, and they cause severe dis-
turbance of the respiration, and ultimately lead to the
death of the animal. The forms which have as yet been
found are species of aspergillus and mucor ; possibly the
same which grow also in mammals and in man.

In man epiphytic development of pathogenic mould
fungi is frequently met with on the external surface of
the skin, where they set up diseases of the skin (favus,
tinea tonsurans, &c.). Certain species of aspergillus
and mucor also frequently develop on collections of dead
portions of tissue, for example, on the coating of the
tongue, in the contents of a dilated stomach, in cavities
of the lungs, &c. ; also in the external auditory canal
and on the cornea, where they set up inflammation. — If
spores of saprophytic mould fungi (penicillium) are in-
jected into the circulation of dogs or rabbits, they stick
on the walls of the capillaries, or in the endothelial
cells, especially in the liver, spleen, and medulla of bone,
and they may remain there for a long time without

* Vortriifje im arzil. Vertin zu Miinchtn, 1881.

MOULD FUNGI AS EXCITING AGENTS OF DISEASE. 635

sprouting, and without causing any disturbance.
Wyssokowitsch* was able to demonstrate their presence
in these organs in large numbers even after seven days.
If, on the other hand, the spores of certain species of
aspergillus and mucor were injected into the veins, the
sprouting of the spores occurred at various parts of the
body, and masses of mycelium were formed, which were
visible to the naked eye. If very numerous spores were
injected, and if very large numbers of these mycelium
masses developed, the animals died. As has been above
described (see p. 123), the largest number of the de-
posits after injection of aspergillus and mucor occurred
in certain organs. This apparent choice of certain parts
of the body does not depend only on variation in the
distribution of the spores and on greater deposit of the
spores in certain organs differing according to the species
of fungus injected ; but the sprouting of the spores and
the development of the mycelium in the organs is also
more or less favoured by certain other conditions, so that,
for example, spores of aspergillus glaucus form the most
luxuriant mycelium in the kidneys and in the liver, and
the spores of mucor the most distinct and numerous
deposits in the kidneys, mesenteric glands, and Peyer's
patches, while in other parts the spores either do not
sprout at all or only to a very imperfect degree.

That only a few species of mould fungi occur in the Limited
bodies of warm-blooded animals seems to be chiefly, but of th

not exclusively, due to the fact that only these forms fun^i in the

. , -, animal body

can, at the high temperature of warm-blooded animals,
develop a sufficient amount of energy to enable them to
live in concurrence with the cells of the animal body
(see p. 136). The limitation of their fructification to
the surfaces of the animal body is explained by the
necessity for contact with free air.

On the whole, among the infective agents of higher
animals the mould fungi play only an insignificant part,
the nutrient conditions which they find there are un-
suitable, the temperature being high, the juices of the
body being highly albuminous and weakly alkaline, and

* Zeitschr.f. Hygiene, vol. i., Part 1.

636

VITAL ACTIONS OF THE LOWER FUNGI.

further they are completely surrounded by fluid media,
so that an extensive formation of mycelium or fructifica-
tion can never occur. On the other hand, the chemical
composition as well as the temperature of the juices of
plants furnish better conditions of existence for the
mould fungi, and here, as in the case of insects, they
find an opportunity of quickly penetrating through the
whole mass of the body attacked, and of thus bringing
the mycelial threads into contact with the free air.

Parasitic
yeast fungi.

B. The Budding Fungi as Infective Agents.

Parasitic budding fungi have never as yet been
observed in plants, and in animals they occur extremely
rarely, and then only as epiphytic parasites. The only
known case of the latter kind is that of the fungus of
thrush, which for a time was looked on as a species of
mycoderma. Large numbers of yeast sells also at times
occur in the stomach and intestines of man, and pro-
bably on account of the plentiful supply of saccharine
nutriment, can keep up fermentation for some time,
and can thus occasion certain disturbances.

Parasitic
bacteria.

In plants.

C. Fission Fungi as Causes of Disease.

In contrast to the mould fungi, the bacteria almost
never attack higher plants, while warm-blooded animals
very frequently serve as their hosts. In the affection
known as the yellow disease of hyacinths in Holland, we
have however, according to Wakker,* an exception to this
rule in that an accumulation of yellow gelatinous bacterial
masses occasions the disease of these plants. The low
temperature and the chemical composition of the vegetable
juices is evidently very unfavourable for the development
of bacteria, more especially as the cell juices are almost
always distinctly acid, and thus protect the plants against
the bacteria, which are so sensitive in this respect.
Further, the cellulose which surrounds each individual

* Botan. Centralbl., vol. xiv.

FISSION FUNGI AS CAUSES OF DISEASE. 637

cell cannot be dissolved or penetrated by the majority of
bacteria ; some forms, it is true, can convert the dead
cellulose into sugar, or can cause it to ferment, but even
these organisms appear to be unable, under the other-
wise unfavourable conditions, to live in concurrence with
the living vegetable cells. On the other hand, in the
warm-blooded animals the bacteria find a substratum,
rich in albumen, faintly alkaline, and at a temperature
of about 37° C., and thus they have the most favourable
conditions for their development and multiplication;
hence the bacteria threaten the living animal with much
more serious dangers.

Nevertheless, it is by no means all bacteria which are In animals,
able to live in the living animal ; on the contrary, we
can here also employ the classification given by de Bary,
of obligatory parasites, facultative parasites, and true
saprophytes. The species belonging to the group of the
saprophytes are much more numerous than the others;
bacteria, such as bacillus subtilis, micrococcus flavus,
bacillus erythrosporus, micrococcus aquatilis, and in-
numerable other forms, can be introduced in enormous
quantities into the veins, subcutaneously by the mouth,
or by inhalation into living warm-blooded animals
without causing any injury to the body.

Among the facultative and obligatory parasites, the Various
different species show the most various degrees of patho- pathogenic
genie action. — In considering this question it must be action-
remembered that the parasitic bacteria are often limited
to definite species or races of animals as their hosts,
and that not uncommonly the same species of bacterium
which in one class of animals excites a severe disease,
behaves in regard to another class as a pure saprophyte.
We shall enter more minutely into these important
differences in the chapter on " Predisposition " ; we need
only point out here that we are accustomed to reckon a
species of bacterium among the group of parasites if it
exerts pathogenic action on any one species of animal.

The least amount of parasitic energy is shown by those Bacteria
bacteria which almost never multiply in the interior of ^^ ^ns°
the living body, but vegetate only on the surface, on the means of their

638

VITAL ACTIONS OF THE LOWER FUNGI.

ptomaines
when they
STOW over a
large extent
of surface.

Bacteria
which act as
poisons in
smaller num-
bers, and
which
ultimately
penetrate
into the body.

Bacteria
which readily
penetrate into
the body, and
multiply in its
interior.

Growth in the
body accom-
panied with
necrosis of the
tissue

skin, on the mucous membranes, on wounds, in the in-
testine, &c., and cause injury to the body by producing
ptomaines which, being soluble, penetrate from the sur-
face into the body and there act as poisons. Many of
the bacteria belonging to this class live as a rule as
saprophytes. Some of them excite fermentation and
putrefaction ; they do not injure the living animal at all
so long as they occur in small numbers on the surface,
and it is only when they can develop in large numbers,
and when they are not removed from time to time, as
occurs under normal conditions, that the production of
ptomaines is so marked that injury to the host ensues.

Some bacteria have a more marked pathogenic cha-
racter, in that they produce very poisonous ptomaines,
to which the bodies of warm-blooded animals have not
become gradually adapted. Hence these injure the
organism, even when they are growing only over a slight
extent of surface. It not uncommonly happens in this
case that the ptomaine action is only the precursor of the
invasion of the bacteria into the interior of the body ;
the latter is so weakened by the poisoning that the
bacteria find less resistance, and can develop in the
blood and in the organs, which previously could easily
have resisted their invasion.

A further stage in the development of parasitismus
is represented by those bacteria which, without further
assistance, and in relatively small numbers, can establish
themselves in the interior of the living body and multiply
there. These either lead to local morbid processes
(tuberculosis, pneumonia) at the place of entrance, or
they spread through the whole body with the circulation,
and grow in the whole of the capillary vascular system.
The bacteria then occasion either morbid growth of tissue
or necrotic destruction of tissue, or the mechanical dis-
turbances of the tissue change and of the cell life which
results from the distribution and multiplication of the
bacteria leads to grave injury to the animal by means
again of specific ptomaines.

The gradual spreading necrosis of the tissue, and the
spread of the bacterial growth into new territory killed

FISSION FUNGI AS CAUSES OF DISEASE. 639

by the action of the products, is very characteristically
seen in the progressive necrosis of tissue observed by
Koch in the case of mice (see p. 209), also in connec-
tion with the bacilli of pigeon diphtheria, &c. (see
p. 326). It is probable that such bacteria do not
always lead to a progressive destruction of the tissue ; at
times it is evident that such a violent reaction and such
a great new formation of cells occurs that the develop-
ment of the bacteria and the production of the injurious
materials cannot keep pace with it; in that case the
inflammation indicates the limit and the end of the
bacterial development.

Another mode of development within the living body Development
is illustrated for example by the bacilli of malignant parasites. 10
oedema, and of symptomatic anthrax. These bacilli,
belonging to the class of anaerobes, are not able to
multiply in the living blood, nor in open wounds, nor
can they grow when introduced in minute quantities ;
on the contrary, they require the previous occurrence of
an injury which must furnish at least a certain amount
of dead tissue, and further they must be present in large
numbers from the beginning; or if a wound is present
oxygen must to a certain extent be excluded from it ;
further, the bacilli do not penetrate in all directions in
the various tissues of the body, they only grow where
the smallest amount of interchange of gases renders
their existence easier, for example in the subcuta-
neous cellular tissue, or in the serous coverings of
the organs ; and it is only when the whole body
has become extremely poor in oxygen — as a rule only
after death — that they are able to develop in the blood
and in the various internal organs.

Another mode of spread and penetration is shown by Penetration
the micrococci of erysipelas. These also do not multiply lymphatic
in the blood-vessels, nor, when injected into the veins, vessels-
do they cause any disease of internal organs ; on the
contrary, they only grow in the lymph channels of the
skin, exciting here a locally limited inflammation, and
furnishing also, in all probability, toxic materials, by
the absorption of which the marked general symptoms

640 VITAL ACTIONS OF THE LOWER FUNGI.

are produced. They do not show any very great para-
sitic energy, because, as a rule, they are only found in a
living state at the margin of the erysipelas, and appa-
rently very readily succumb to the influence of the living
tissue cells which accumulate there.
Penetration Lastly, those species of bacteria which cause the

into, and • .

multiplication numerous forms of septicaemia and pyaemia which have
blood-vessels. ^een cl°sely studied in animals, live and act chiefly in
the blood-vessels. They multiply most readily and
rapidly in the free blood current ; they are found espe-
cially in the smaller vessels and in the capillaries in
such numbers that the vessels are here and there com-
pletely filled with them, or the blood corpuscles appear
embedded in a large mass of bacteria. They form a
thick layer on the walls of the vessels, and their distri-
bution is so extensive that, on making sections from any
internal organ, almost all the capillaries in every pre-
paration are found completely lined by them. Many
bacteria also attack the colourless blood corpuscles ; in
preparations of such blood large plasma cells are found,
which are quite filled with bacteria, others are met with
in the stage of decay, which has evidently been caused
by the entrance of the bacteria (as in the so-called mouse
septicaemia, p. 310). As the result of this extensive
distribution of the bacteria serious alterations must occur
in the tissue change of all the tissues involved ; the energy
of the nutrient stream which passes into the tissues
from the capillaries, the removal of the waste products
formed in the tissue cells, and the exchange of gases in
the tissue, must all undergo a marked alteration ; in
correspondence with the altered nutrition of the cells
there is an alteration in their functional activity, in the
first place, in that more extensive decomposition of the
material which is present occurs, for which, on the other
hand, there is no corresponding substitute ; in like
manner the new formation of cells, in place of those
which are exhausted or dead, does not occur in a normal
manner. Finally, in addition, we have perhaps also the
production of specific noxious materials on the part of
the prowino- bacteria, and thus there results a complete

FISSION FUNGI AS CAUSAL AGENTS OF DISEASE. 641

disturbance of the tissue change and of the arrangements
which regulate the functions of the body, and this dis-
turbance goes on till severe general morbid symptoms
occur, which usually lead to death. — Some of the micro- Embolism,
organisms which belong to this class may very readily
lead to blocking of the smaller blood-vessels, either by
their accumulation in large numbers, or by the heap-
ing up of materials which have arisen from the break-
ing up of the plasma cells ; in such cases there very
readily occurs, in parts, necrosis of the surrounding
tissue, and subsequent development of the bacteria in
this tissue, which still further degenerates under the
direct action of the organisms. At times the most active
multiplication of the bacteria in the capillary system
only occurs in one or some organs which are particularly
predisposed, and thus the emboli often show a predilec-
tion for certain organs. Thus it happens that the local
symptoms are often the most striking, and that the type
of the disease varies markedly, according as in the one
case the general phenomena, in the other, these or those
local symptoms are prominent.

The power possessed by a limited number of bacteria Biological
of leading a parasitic existence in the body of warm- of tSe patifo-
blooded animals raises the question to what biological genie bacteria,
peculiarities of these bacteria this power is due ; what
differences exist between their properties and those of
the saprophytic bacteria ; what are the protective arrange-
ments of the living body which render the multiplica-
tion and development of the latter impossible, but which,
on the other hand, are powerless against these patho-
genic bacteria ?

The attempt was formerly made to explain this rela- Eesistance
tion by the aid of some one active factor in the living J^^^enta of
organism. Thus, it has been pointed out that it is the fluids of

-ui xi A \ i • • .the body?

possible that some bacteria can only grow in a quiescent

medium and not in the fluids of the body which are in
active movement, and it has been supposed that

41

642

VITAL ACTIONS OF THE LOWER FUNGI.

Resistance

against

oxygen?

Horvath's experiments give some support to this view.
But these experiments, and the control experiments
which have been since made, do not, as has been men-
tioned above (p. 535), yield any satisfactory results,
applicable to the continuous flowing movement of the
fluids of the body.

The supposition has also been frequently expressed
that the bacteria which are able to live in the living
body are only those which find there a sufficient supply
of oxygen, and as Szpilmann had shown that anthrax
bacilli are not destroyed by the action of ozone, while
putrefactive bacilli are rapidly killed, there seemed to be
some ground for this view. — But more accurate experi-
ments which have been made by Liborius,* as to the
requirement of oxygen by the pathogenic bacteria, have
shown that these are obligatory or facultative anaerobes,
and require much less oxygen than a large number of
saprophytes. On the contrary, a certain indifference
with regard to oxygen seems to be a necessary condi-
tion for the parasitic existence of the bacteria ; it is
only thus that they are able to develop a large amount
of vegetative energy in parts of the body in which the
tension of the oxygen is very low.

Further, the view has been frequently expressed that

against excre- ., ,. . , n . . ,1-11 ~

tion from the the living body tries to prevent the development of
bacteria by continually eliminating any organisms
which get into the blood stream by the kidneys,
and ultimately by other secretory organs, from which
it would follow that only those bacteria are capable of
growing in the body which can multiply in the material
present in it and at that temperature with such aa
amount of energy that the continued elimination of a
large number of the bacteria is provided for. — But by
the researches of Wyssokowitsch* it has been definitely-
shown that the normal living body does not excrete
saprophytic and pathogenic bacteria. This only takes
place when pathogenic bacteria have become deposited
and have grown in a secretory organ, and when, in con-
sequence of this growth, injury to the tissue of the

* Ztitschr.f. Hygiene, vol. i., Part 1.

Resistance

FISSION FUNGI AS CAUSAL AGENTS OF DISEASE. 643

organ has occurred. — Besides, it may be easily seen that Preference
the nutrient material present in the body of warm- nutrient con-
blooded animals, and the temperature of the body, are j^™8 in the
not specially favourable for the pathogenic organisms,
and do not enable them to multiply more rapidly than
the saprophytes ; for in a dead body, kept at 37° C., the
saprophytes obtain the mastery in a short time, even
when they have been introduced in smaller numbers
than the pathogenic bacteria.

This want of influence of the movements of the Resistance t3
fluid, of the tension of the oxygen, of the secretory ceiis?ving
functions, of the temperature, and of the chemical com-
position of the body on the one hand, and on the other
hand the fundamental alteration of the conditions of
existence of bacteria when death of the body occurs,
shows us that it is in the protoplasm of the living cells
that the most important factor, and that which regulates
the differences in the behaviour of saprophytes and
parasites, lies. Only those bacteria can be reckoned in
the latter class which are able to obtain the mastery,
and to multiply in concurrence with the living cells,
while the saprophytes are not able to grow when sub-
jected to the influence of the living cells, but on the
contrary die. Thus the living cells would form the seat
where the body carries on the battle with the invading
bacteria, where the saprophytes are destroyed, and where
the parasitic bacteria gain the victory.

This view of a battle between the cells and bacteria,
for a time only obtained by deduction, seems to have
gained a definite support from the experiments of
Metschnikoff. He was able in experiments with a Metschnikoffs
yeast parasite of daphnis, as well as in experiments with
anthrax bacilli, which he introduced under the skin
of frogs, to observe that bacteria are taken up by
leucocytes ; the bacteria were gradually destroyed in the
substance of the leucocytes, being as it were, digested.
Metschnikoff at a later period made similar observa-
tions in rabbits and guinea-pigs which he had in-
oculated with attenuated anthrax bacilli. Nevertheless,
Metschnikoff's experiments are by no means free from

644

VITAL ACTIONS OF THE LOWER FUNGI.

Wyssoko-
witsch's in-
vestigations.

objection, and a large number of control investigations
which were made in the author's laboratory by Wysso-
kowitsch led to a totally different result, and showed
that after introduction of large quantities of saprophytic
and pathogenic bacteria into the blood stream of warm-
blooded animals the leucocytes did not take them up.
They play no It is only some specific forms of bacteria which are
bfoodedW£ n f°un(l constantly in large numbers within the colourless
animals. blood corpuscles, such as the bacilli of Koch's mouse
septicaemia, or of swine erysipelas. In these cases,
however, the leucocytes which occur in all stages of
degeneration give much more the impression as if they
were the attacked and decaying part, and the bacteria,
on the other hand, of which large numbers are found in
the dying cells, as if they were the victorious agents.

Certain other cellular elements of the body seem,
however, as a matter of fact, to play an important part
in the battle with the invading bacteria. According to
the more recent investigations by Wyssokowitsch,
bacteria, both saprophytic and pathogenic, when intro-
duced into the blood of warm-blooded animals are in the
first place very rapidly eliminated from the circulating
blood, in a similar manner as has formerly been shown
in the case of particles of colouring matter. This dis-
appearance from the blood stream is not occasioned by
excretion of the bacteria in any of the secretions, nor by
their destruction in the circulating blood ; but the
bacteria are fixed in the capillaries of various organs,
chiefly of those where the current of blood is slow ; they
adhere to the walls of the capillaries, or are taken up
into the interior of the endothelial cells. These bacteria
are found in largest numbers in the liver, spleen, and
medulla of bone. The fight with the parasites seems to
occur at the seat of deposit chiefly in the endothelial
Death of non- cells, which results either in death of the bacteria or in
bactenaTnthe *^e destruction of the cells which are immediately con-
endotheiiai cerned, and the multiplication of the bacteria. It can
be observed that typical saprophytes die at the seat of
deposit in a relatively short time — within a few hours —
and bacteria which are pathogenic for other species of

Fixation of
the bacteria
on the walls
of the
capillaries.

FISSION FUNGI AS CAUSAL AGENTS OF DISEASE. 645

animals, within twenty-four to forty- eight hours. It is
only the spores of saprophytes, for example of bacillus
subtilis, which evidently play the part of completely
indifferent foreign elements, that were found alive and
capable of development after about three months in the
endothelial cells of the capillaries of the spleen and liver.

When the bacteria do not enter in large numbers nor
directly into the blood, but in small numbers through
slight injuries of the skin or of the mucous membrane,
a similar battle between the bacteria and the tissue and
endothelial cells of the immediate neighbourhood,
probably also occurs in the first instance, and thus all
those bacteria are pathogenic for a definite species of
animal which, after their contact with these cells, are
able to grow and multiply, while the cells, on the con-
trary, undergo pathological alterations or die.

We obtain, also, a further insight into the causes of
the pathogenic action of bacteria by some experiments,
which will shortly be published by Wyssokowitsch, in
which he succeeded, by artificially lowering the energy
of the cells of the body, in enabling bacteria which,
under ordinary circumstances, are not pathogenic for
the animals employed, to multiply rapidly and occupy
the whole of the living body. Such a weakening of the Non-patko-
body resulted, for example, by the employment of high
temperatures approaching closely the body temperature ^n
by which the tissue change was as much as possible artificially
reduced ; further, by certain mineral poisons, such as wea
chroniate of ammonia ; by far the most completely and
rapidly, however, by some of the ptomaines furnished
by bacteria. The products furnished by bacillus crassus Influence of
sputigenus, by bacillus Neapolitanus, &c., act apparently p
on the walls of the capillary vessels, and alter the endo-
thelial cells in such a manner that small quantities of
micrococcus tetragenus, Finkler's spirillum, bacillus
pneumoniae, and other species of bacteria, not at all
injurious to normal rabbits, can multiply in enormous
numbers after the injection of these products, are not
completely removed from the blood stream, and do not
die in the endothelial cells.

G46 VITAL ACTIONS OF THE LOWER FUNGI.

It is probable that we must explain in an analogous
manner the former experiments by Salomon sen as to the
action of jequirity on frogs (p. 348) ; further, the in-
fluence of papayotin on the number of bacteria in the
blood, as observed by Rossbach. The investigations in
this direction must be still more extended and varied
before we can draw general conclusions from them ; we
may, however, expect that they will ultimately enable us
to obtain definite views as to the more intimate details
of the battle which occurs between cells and bacteria.

647

PART V.

CONDITIONS AFFECTING THE DEATH OF THE LOWER
FUNGI.

Various external influences cause injury to the lower Disinfection.
fungi, and affect their vital activity more or less pro-
foundly. All these injurious factors are evidently of
great interest, hecause we must search among them for
the means to enahle us to oppose the grave dangers
which threaten us on the part of the fungi, namely, the
infective diseases; and the whole of the influences
which alter the normal life of the lower fungi are
usually considered together under the heading " Modes
of Disinfection."

Very numerous experiments have heen already made Difference in
with regard to the mode and the degree of action of the means ac-

disinfecting means ; these must, nevertheless, be still ^^Jf £ the
greatly expanded. For just as in the study of the fungus.
biological characters of the fungi, so in this case it has
been found that the various species do not behave in
the same manner, but that the one is most markedly
affected by this influence, the other by that ; and that,
further, the sum total of the other conditions of life
which are present influences the action of the individual
disinfecting means. High temperatures injure the fungi According to

v? , ! -, . , J Bx the other con-

more readily when bad nutrient materials are present at ditions of life.
the same time ; the active dose of specific poisons varies
according as the external conditions represent the op-
timum or vary from the optimum. The stage of deve-
lopment of the bacteria has also a marked influence
on their resisting power ; young individuals as a rule
are more resisting, while older individuals which are
approaching the stage of involution can be destroyed

648 CONDITIONS AFFECTING THE DEATH OF FUNGI.

According to by trivial and transient injuries. The effect of the
development, formation of spores is of very special importance. If
we have to deal with organisms which form these
extremely resisting bodies, means which would greatly
injure, or even destroy, other fungi may be entirely
without effect. Hence in disinfection experiments
spore-bearing and non-spore-bearing organisms must
not be mixed together, each must be tested separately.

Among the means of disinfection we reckon not only
those which kill and destroy the organisms, but also
those influences which only cause a permanent loss or a
diminution in activity of some of their vital phenomena,
and even those which only occasion a temporary delay
in their growth and multiplication. These different
degrees of degeneration and death require a separate
discussion.

Inhibition of
development.

Inhibition of
individual
vital pheno-
mena.

I. — Inhibitory Means.

The smallest degree of injury which micro-organisms
can experience, as the result of external influences, con-
sists in a disturbance of their complete development,
which only lasts so long as the injurious factors are
present, while afterwards under normal conditions the
ordinary vital phenomena can again go on undisturbed.

Minute departures from the normal conditions of
existence often lead to cessation of some one biological
function. Thus by alterations in the nutrient substrata,
by diminution in the amount of oxygen, by a tempera-
ture somewhat too low or too high, we may have cessa-
tion of the swarming power, of the secretion of peptonising
ferments, of the fermentative action, of the production
of colouring matter, or of the spore formation ; while
otherwise growth, multiplication, and all other vital
phenomena remain unaltered. Their power in pro-
ducing disease also may be influenced by similar trivial
alterations in the conditions of life, and may even be
temporarily removed ; and it would be a matter of great
interest to learn more accurately the various means — for
example, small doses of specific poisons, alterations in

INHIBITORY MEANS. 649

temperature, &c. — by the employment of which we might
be able for a certain time to neutralise the superiority of
the pathogenic bacteria over the cells of the animal body.

The cessation of all vital phenomena, and also of Complete
growth and multiplication, is only brought about by development,
marked abnormalities in the external conditions. A
partial interference with growth is produced by all those
alterations in the conditions of existence which lead to
a departure from the optimum. These most favourable
conditions of existence have been referred to already in
detail, and it has also been pointed out in what way
every variation of temperature, concentration, &c.,
beyond a certain limit results in interference with the
vital energy of the fungi.

Complete cessation of growth frequently occurs as the Withdrawal
result of gradual exhaustion of the nutrient materials. nutrientSary
In every nutrient medium it ultimately happens, as the materials,
result of continued multiplication of the fungi, that
some or all of the colonies no longer find the nutrient
materials necessary for their further development. In
fluids the yeast or fission fungi which have already
formed are deposited in the form of a powdery precipi-
tate on the bottom of the vessel. It depends chiefly on
the species of the fungus in question how long they can
retain their vitality under such conditions without a
fresh supply of nutriment. Some only exist in a latent
condition for a short time, they soon degenerate and
break up ; others are much more resisting. To the
first group belong the majority of the micrococci, to the
latter the spore-forming bacilli, the spores of which
can retain their vitality for years ; but many micrococci
also — for example, Staphylococcus aureus — show a
similar resisting power. It is not necessary that all
the nutrient materials should be exhausted ; on the con-
trary, the loss of a single necessary material is sufficient
to lead to a period of rest.

A very frequent cause of cessation of the growth of withdrawal
bacteria is the diminution of the necessary amount of of water-
water in the nutrient medium. Growth ceases on the
most various nutrient media on the surface of the soil,

650 CONDITIONS AFFECTING THE DEATH OF FUNGI.

&c., whenever the amount of water has fallen below 60
to 70 per cent. ; more accurate determination of these
limits is, however, wanting.

Light, Among other influences light and pressure seem scarcely

electricity, to esert any noticeable effect on the development of the
and pressure. , „ . ^ T^I-P * . i

lower fungi. Certes and Locnin round that yeast could break

up sugar under a pressure of 300 to 400 atmospheres ; in like
manner putrefactive phenomena occurred in fluids which
were kept under a pressure of 350 to 500 atmospheres. —
Electricity, in the form of the constant galvanic current,
causes cessation of the multiplication of the bacteria ; this
effect is due to the electrolytic action of the current, which
leads to the production at the positive pole of a distinctly
acid reaction, and at the negative pole of a distinctly alkaline
one. No influence is noticeable when the current is weak ;
the effect is not produced till at least two powerful elements
are employed.

Temperature. Of much greater practical importance is the tempera-
ture of the nutrient medium. At a low temperature as
well as at a high temperature multiplication of bacteria
(and also of mould fungi) ceases; but in almost all species
the limit of the low and high temperature appears to be
different. In the case of many organisms these limits
have not yet been accurately determined. In the case of
many saprophytes (the water bacteria, the organisms
formerly grouped under the term ''bacterium termo,"
&c.) slight growth may occur at a temperature of + 6°
C., and development only ceases at a temperature of
from 4° to 5° C. On the other hand, the lowest limit of
growth for the spirillum of Asiatic cholera is from 15° to
16° C.; for the bacilli of glanders, about 22° C.; and
for the tubercle bacilli, 33° C. Cessation of multipli-
cation as the result of higher temperatures occurs : in
the case of the lactic acid bacillus, above 45*3° C.; in the
case of bacterium termo, from 40° to 43° C.; in the case
of bacillus subtilis, at 50° to 55° C. The higher limit
is difficult to ascertain, because the temperature which
only leads to temporary cessation of vital activity, and
that which — more especially when it acts for a consider-
able time — causes permanent loss of certain properties,
usually lie very close to each other.

INHIBITORY MEANS. 651

Of great practical importance also is the cessation of Chemical
development as the result of the addition of small quan- p(
tities of active chemical and specifically poisonous mate-
rials to the nutrient substrata. Here also it is not easy to
ascertain precisely the value of these means, because they
behave very differently according to the composition of the
nutrient substrata. This difference chiefly depends on Difference in
the fact that when these chemical materials are added according to
to the nutrient substrata, chemical decompositions fre- ]Je na^ure °f

the nutrient

quently occur, as the result of which a portion of the substratum.
disinfecting substance is destroyed or rendered inactive.
Hence it is clear that definite values of the inhibitory
means can only be laid down in the case of one and the
same nutrient solution, while the values will differ where
the composition of the nutrient substratum varies. For
example, Boillat* ascertained that in albuminous sub-
strata chloride of zinc and other metallic salts only
produced a disinfecting action after all the albumen was
precipitated by them, and when a sufficient excess
remained in the solution for purposes of disinfection.
Further, as mentioned above, various species of fungi
behave differently towards noxious agencies, and in the
same species the degree of the action always depends on
the other conditions of life which may be present at the
same time. Hence a generally applicable scale of the
value of disinfecting substances cannot be given ; and in
like manner trustworthy results are only obtained from
those experiments which have been made with known
and well- characterised species of bacteria.

Of the figures which have been as yet published we Experiments
may mention here only a few, some of which, however, ^th bacteria*

have not been obtained by the employment of all the in meat in-
above-mentioned precautions. De la Croix tested the
bacteria of meat infusion (that is to say, not a pure
cultivation of a single species), and found that their
development in meat infusion ceased when the following
substances were present in the degree of concentration
mentioned below : —

* Journ.f. prakt, C/iem., N.F., vol. xxv.

652 CONDITIONS AFFECTING THE DEATH OF FUNGI.

Sublimate 1 30,208

Chlorine 1 25,250

Chloride of lime 1 11,135

Sulphurous acid 1 6,448

Bromine 1 6,308

Sulphuric acid 1 5,734

Iodine 1 5,020

Oilofmustard 1 3,353

Salicylic acid 1 1,003

Permanganate of potash 1 1,001

Carbolic acid 1 669

Borax 1 62

Alcohol 1 21

By Katimoff According to Katimoff, in order to render meat infu-
sion aseptic, the following concentrations were neces-
sary : —

Sublimate 1 : 13,300

Nitrate of silver 1 : 10,000

Iodine 1: 8,000

Carbolic acid 1 : 400

In order to prevent the development of bacteria on
meat, about 30 times the amount given above was
necessary.

By Miguel. According to Miguel's experiments, development of
bacteria in meat infusion is prevented by —

Mercuric oxide

Peroxide of hydrogen

Mercuric chloride

Nitrate of silver

Iodine

Chlorine

1
1
1
1

1
1

Bromine 1

1
1

Mineral acids . . 1 : 500 to 1

Sulphate of copper
Salicylic acid

Carbolic acid

Permanganate of potash

Arsenious acid

Boracic acid

Sulphate of iron

Borax

yEthylic alcohol

Iodide of potash

40,000

20,000

14,300

12,500

4,000

4,000

1,667

1,100

1,000

333

313

286

170

130

90

14

10-5

7

INHIBITORY MEANS.

653

Koch has tested the inhibitory action of various poisons Experiments
on non- spore -bearing anthrax bacilli. The results were
obtained by tilling small vessels with 10 com. of blood
serum or of peptonised meat infusion (1 per cent, peptone,
^ per cent, meat extract and water), and then adding the
disinfecting substances. A number of these vessels, and
among them some without any disinfecting substances,
were placed side by side under a bell-jar in the presence
of moisture. A silk thread, impregnated with anthrax
spores, was then placed in each vessel ; in the control
vessels growths of long anthrax threads were always pre-
sent after twenty-four hours, and presented a very charac-
teristic appearance, and one not easily mistaken. In a
similar manner the other vessels were examined under the
microscope in the course of the next few days, and thus
absence of growth or the appearance of threads indicated
the activity or inactivity of the disinfecting means. (In
the case of other species of bacteria nutrient gelatine is
often preferable for these experiments, the chemical
substance to be tested, and also a small quantity of the
bacteria, being added to it, and then the liquefied jelly
poured out on glass plates.) The following are the most
important figures obtained by Koch : —

Distinct hindering of Complete cessa-
growth tion of growth

Occurred when the concentration reached

Bichloride of mercury
Oil of mustard
Allyl-alcohol

^

1
1

1,600,000
330,000
167,000 ......

Arseniate of potash
Thymol
Oil of turpentine

1
1
1

100,000
80,000
75,000

Hydrocyanic acid

1

40,000 ....

Oil of peppermint
„ cloves
Potash, soap

1
1

-|

33,000
5,000
5,000

Iodine

1

5,000

Hydrochloric acid
Boracic acid
Bromine |

1
1

1

2,500
1,250

1,500

Chlorine J
Permanganate of potash...

1

1,400

300,000
33,000

10,000

8,000

1,000

1,700
800

654 CONDITIONS AFFECTING THE DEATH OF FUNGI.

Distinct hindering of Complete cessa-

growth tion of growth

Occurred when the concentration reached

Salicylic acid 1

Benzoic „ 1

Carbolic „ 1

Benzoate of soda 1

Camphor 1

Quinine 1

Alcohol 1

Common salt ... 1

3,300 1 : 1,500

2,000

1,250 1 : 850

200 —

2,500, over 1 : 1,250

830 1 : 625

100 1 : 12-5

64 .. —

Action of A series of experiments by Kichet* may also be mentioned

various where the fluid employed was a mixture of 900 erammes of

metallic salts 1AA „ ,. , n&^

sea-water, 100 grammes or neutralised urme, and 1 gramme

of peptone, the attempt being made to ascertain how much
of the various metallic salts it was necessary to add to this
solution to prevent the development of bacteria. In the
following table the amount of the pure metal has been calcu-
lated from the amount of the metallic salt which it was
necessary to add to each litre of fluid, and also for comparison
those figures are given which correspond to the quantity of
metal per litre which was necessary to kill salt water fish.
From this comparison we see at once the much greater
resisting power of the bacteria, and also the unequal behaviour
of certain metallic poisons in reference to the animal and
vegetable cell.

Amount of metal per litre of fluid
To hinder the development To kill fish,
of bacteria.

Mercury 0'0055 gramme . . . 0'00029 gramme

Zinc 0-026 „ ... 0'0084

Copper 0-062 „ ... 0'0033

Iron 0-24 „ ... 0'014

Barium 3'35 „ ... 078

Manganese 77 „ ... 0*3 „

Ammonium 187 „ ... 0'064 „

Calcium 30'0 „ ... 2'4

Sodium 43-0 „ ... 24'0

Potassium 58*0 „ ... 01

Of the inhibitory substances not included in the foregoing
tables, but which have been tested and recommended, we may
mention the following : —

Other According to the experiments of Wassilefff calomel has an
disinfecting —

substances. , , _„

* Compt. rend., vol. 97.

•f Zeitschr.f. physiol. Client,, vol. vi.

ATTENUATION OF ORGANISMS. 655

energetic action in preventing putrefaction, whilst it does
not interfere with the activity of the digestive ferments. —
According to Schulz and Hoffmann organic acids of the fatty
series, citric acid, formic acid, &c., are powerful antiputre-
factive substances ; formic acid in the amount of '25 per
cent, is able to preserve Bucholtz's nutrient fluid for months.
According to Donath* chinolin is antiputref active in the
percentage of '2, and according to Yigierforthophenolsulpho-
acid is active in a percentage of '5 to 1. — Bert and Eegnard^
have made experiments as to the antiseptic and disinfecting
properties of peroxide of hydrogen, and Chappuis § on ozone,
but without paying sufficient attention to the dose of the
substance and the species of the bacterium. — Kolbe || has
drawn attention to the fact that when kept in vessels filled
with carbonic acid fresh ox flesh can be preserved against
putrefaction for four to five weeks ; mutton cannot, however,
be similarly preserved. More accurate examination of the
antiseptic properties of carbonic acid is desirable.

According to experiments by Kuisl^f potash soap is not
such a good inhibitory substance for other bacteria as for
anthrax bacilli. Even when present in a concentration of 10
per cent, it was not able to prevent putrefaction in meat.

II. — Attenuation of Pathogenic and Fermentative
Organisms.

By noxious influences of definite but closely limited Attenuation
intensity we may so alter many bacteria that they lose °
certain of their vital functions, this loss lasting for a
long time and even when the cultivation is continued
under completely normal conditions. The noxious
factors which are suitable for this action are less ener-
getic than those which cause complete death of the
bacteria; on the other hand, the effects are more marked
than in the case of the inhibitory means, which only
exert their action so long as they are present in the
nutrient substratum. At times, however, the greater
effect necessary for attenuation can also be produced by
sufficiently long-continued action of the milder means.
When properly regulated, high temperatures and various

* Chem. Ber., vol. 14. t Mem. soc. biolog., 1884.

J Compt. rend., vol. 94. § Bull. soc. Chim., vol. 35.

|| Journ.f.prakt. Chem., (2) vol. 26.
1 Munch, urztl. IntdligenzbL, 1885.

656 CONDITIONS AFFECTING THE DEATH OF FUNGI.

The more
intimate
nature of
attenuation.

Attenuation
of the agents
of fermenta-
tion.

Attenuation
of pathogenic
bacteria.

Anthrax
bacilli.
Attenuation
by high tem-
peratures.

chemical poisons are able to produce a permanent at-
tenuation.

The vital phenomena which are in this way lost are,
as far as has yet heen ascertained, only the power of
producing fermentation and that of exciting disease. A
similar occurrence has not heen observed in the case of
the other functions and products of the tissue change
(pigment, ferments, &c.). The loss of the fermentative
or pathogenic properties is usually designated shortly
under the term " attenuation of the bacteria." Whether
at the same time there is diminished energy of growth
and of the whole phenomena of tissue change in the
pathogenic bacteria, thus explaining the victory of the
cells of the body, or whether it is only one of the vital
phenomena which is of importance in the warfare with
the cells of the body, namely, the production of a poison,
&c., which is acted on by the noxious agent and destroyed
for a considerable time, can only be decided as the result
of further investigations.

Attenuation of the pathogenic mould fungi has not as
yet been observed ; see the above-mentioned experiments
by Frankel, p 126.

As regards the attenuation of the fermentative bacteria
we have observations by Fitz. The anaerobic bacillus
butyricus could be so altered by heating it for five hours
at a temperature of 90° C., or for seven hours at 84° C.,
that it no longer furnished the characteristic fermen-
tative products in suitable materials although it multi-
plied actively. In like manner the agent of butyric
fermentation isolated by Fitz at a later period (p. 388), as
well as the bacillus Fitzianus, lost readily the power of
producing fermentation, but also readily regained it.

The attenuation of pathogenic bacteria has as yet been
successful in the case of bacillus anthracis, the bacillus
of symptomatic anthrax, the bacillus of fowl cholera, the
bacillus of swine erysipelas, and the as yet unknown ex-
citing agent of hydrophobia.

The phenomenon of attenuation has been most accu-
rately studied in the case of the anthrax bacilli. The
employment of high degrees of temperature has proved

ATTENUATION OF ORGANISMS. 657

to be a very suitable means ; the temperature may vary
between 42° and 55° C,, and the organisms must be ex-
posed to it for a longer time the lower the temperature
employed. Thus according to Toussaint a temperature
of 55° C. was able to attenuate the bacilli of an anthrax
cultivation in ten minutes ; according to Chauveau a tem-
perature of 52 °C. must be employed for fifteen minutes, of
50° C. for twenty minutes, of 47° C. for one to four hours
after previous exposure to 42° to 43° C. for twenty hours ;
according to Pasteur and Koch a temperature of 43° C.
must be employed for six days, a temperature of 42° C.
for about twenty-eight to thirty days, in order to obtain a
•complete loss of the pathogenic action ; where the action
is continued above thirty days death of the bacilli occurs.

According to Pasteur's recommendations, which have Most suitable
been more precisely worked out by Koch, the following m
is the method best suited for obtaining attenuated an-
thrax bacilli : the cultivations are made in neutralised
chicken broth, which is placed in a moderately deep layer
in Erlenmeyer's flasks. These flasks are then placed in
a D'Arsonval's thermostat kept at 42° C. In spite of
careful regulation the temperature varies somewhat in
the interior ; and hence the individual vessels frequently
show a somewhat varying degree of attenuation. At
times, also, spore formation may take place, though as a
rule this does not occur at 42° C. ; if it does take place the
attempt at attenuation fails. Hence it must always be
borne in mind that some of the cultivations may not have
succeeded. From eight days onwards the vessels must
be tested daily ; and the degree of attenuation of each
specimen is ascertained either by sowing the material in
a vessel containing chicken-broth and kept at 37° C., so
that spores are soon formed ; or by inoculating a mouse
with the specimen, and after its death making culti-
vations from the spleen, and thus obtaining spores. The
cultivations or spores so obtained preserve for a long
time that degree of virulence at which the material had
arrived.

After exposure to a temperature of 42° C. for ten days Various
the anthrax bacilli are so attenuated that rabbits and attenuation

42

658 CONDITIONS AFFECTING THE DEATH OF FUNGI.

Return of
attenuated
bacilli to
virulent
bacilli.

guinea-pigs show almost no reaction when inoculated ;
at a somewhat earlier period, guinea-pigs, but not
rabbits, are killed. From the tenth to the twenty-fourth
day we obtain the so-called " mouse anthrax," that is to
say, a cultivation of bacilli which is only able to kill
mice. These attenuated bacilli behave, according to
Koch, somewhat differently in the body of the mouse
than the virulent bacilli, the capillaries of the lung be-
coming filled with extremely long pseudo-threads in a
manner which is not observed in the case of ordinary
anthrax.

The first and second vaccines prepared by Pasteur for
the protective inoculation of sheep are treated for twelve
and twenty-four days respectively in the manner above
described.

According to Pasteur's view the oxygen of the air
is the chief active agent in this process of attenua-
tion ; while Koch regards the temperature as the most
important factor, its effect being perhaps also aided
by certain products of tissue change of the bacilli. The
results of attenuation experiments at varying high tem-
peratures show most distinctly that the effect depends
almost exclusively on the temperature, and is in fact the
result of the action of a certain temperature, as well as
of the length of time to which the material is exposed to
it.

In the case of anthrax bacilli attenuated in this
manner, researches have been made as to whether they
regain their former virulence when cultivated under nor-
mal conditions, or whether they permanently retain the
attenuated virulence when once it is acquired. On the
whole the experiments have not given an uniform result,
and are as yet too few in number to enable us to deduce
any law which accounts for the return of the virulence
in some cases, and the absence of such return in others.
The virulence appears to be regained most readily and
most regularly where the attenuation has been brought
about, according to Toussaint's method, by the short
action of high temperatures ; the bacilli which have been
attenuated by ten minutes' exposure to 55° C. regain

ATTENUATION OF ORGANISMS. 659

their virulence, according to Chauveau, in the first normal
cultivation, and this is also the case where a temperature
of 47° C. has been employed; on the other hand, where,
in Pasteur's method, a temperature of only 42° to 43° C. is
employed, there is as a rule no return of virulence. Thus
Koch cultivated completely attenuated anthrax bacilli
which had been kept for twenty-nine days at 42° C. for
two j'ears under the most favourable conditions without
the last cultivations being able even to infect mice ; at
the same time, however, the morphological characters of
the bacilli and the appearance of the colonies did not show
any difference from those of the virulent bacilli. — Ac-
cording to Pasteur the virulence can be regained if
anthrax bacilli attenuated according to his method are in
the first place inoculated on a newly-born guinea-pig;
this animal succumbs to the infection, and then an
animal one day old is inoculated from the first, then an
animal two days old from the second, and so on ; and
thus ultimately a gradual increase of virulence is obtained,
till even adult animals are killed. Koch, however, on
repeating this experiment was unable to confirm these
results.

Among other means of attenuating anthrax bacilli we Attenuation
may mention the action of chemical substances which bldUiby*
are poisonous to bacteria, a method first employed by carbolic acid
Toussaint, and later by Chamberland and Eoux. Ac-
cording to the latter authors carbolic acid of the strength
of 1 to 600 causes complete attenuation of a cultivation
kept for twenty-four days at 35° C. ; if examined after
twelve days the cultivation still possesses its full virulence.
Solutions of bichromate of potash of the strength of 1 B.v chromic
to 1700 kill anthrax bacilli ; where the dilution is greater
(1 to 2,000 to 1 to 5,000), it only causes such an attenua-
tion that sheep are no longer affected by inoculation,
while guinea-pigs and rabbits still die. If a 2 percent. By sulphurous
solution of sulphurous acid acts for eight to ten days on acid*
anthrax spores at a temperature of 35° C., and if the
spores are then cultivated on normal nutrient jelly, a
growth is obtained which is still able to kill guinea-
pigs, but does not kill rabbits.

660 CONDITIONS AFFECTING THE DEATH OF FUNGI.

By cultivation
in an appa-
ratus kept
constantly in
motion.

By long-
continued
cultivation.

By light and
pressure.

Attenuation
of the bacilli
of fowl
cholera.

Of sympto-
matic anthrax.

Of swine
erysipelas.

Attenuation
of the virus
of rabies.

Bucliner obtained loss of virulence in the anthrax
bacilli if he cultivated them outside the body for a
number of generations in certain nutrient substrata,
such as in extract of meat solution, with or without
peptone, to which a very plentiful supply of air was
added by the employment of an apparatus which kept
the solution in constant motion. There were many
objections to this method as first described by Buchner
(p. 240) ; but protective inoculations which have been
made by Frank with Buchner 's attenuated anthrax bacilli
show that, as a matter of fact, a gradual loss of virulence
can be obtained by this method.

A diminution of virulence also appears to occur when
the anthrax bacilli are kept for a long time in the same
culture fluid (Koch).

Lastly, according to Arloing,* exposure for three
hours to sunlight, and, according to Chauveau and
Wossnessenski,*!* increased atmospheric pressure, cause
an attenuation of the anthrax bacilli.

Among other pathogenic bacteria the bacilli of fowl
cholera, of symptomatic anthrax, and of swine erysipelas
show a similar behaviour. In the case of the first-
mentioned bacillus the mode of the attenuation has not
as yet been accurately ascertained (p. 317) ; in the case of
symptomatic anthrax the attenuation is best obtained by
the employment of high temperatures (p. 301) . A special
and new principle has been followed by Pasteur in the
case of the bacilli of swine erysipelas ; he found that
their virulence was increased by repeated transmission
of the infective agents through pigeons, while, on the
other hand, it was diminished by their acclimatisation
in the bodies of rabbits (p. 307).

Another plan, and one not as yet completely explained,
has been recently employed by Pasteur J for the attenua-
tion of the virulence of the poison of rabies. Pasteur's
method is shortly as follows : — As the infective agents
of rabies are as yet completely unknown, and have not
been cultivated artificially, a pure rabic poison, and

* Compt. rend., vol. 99. f ibid., vcl. 98.

J Compt. rend., 1885, 26th October.

ATTENUATION OF ORGANISMS. 661

one which is practically uniform in its virulence, must
be procured for the attenuation experiments. This is
obtained by continued inoculation of the poison on
rabbits. If one starts from a rabid dog, and inoculates
from this animal a rabbit under the dura mater into the
brain substance, rabies appears in the latter animal after
an incubation period of about fourteen days ; if the in-
oculations are carried on from rabbit to rabbit the period
of incubation becomes gradually shorter ; after 40 to 50
inoculations it has fallen to seven days, and up till the
ninetieth transmission there is scarcely any further
alteration to be observed ; hence the poison has become
acclimatised in the body of the rabbit, and has attained
an almost constant degree of virulence. — It has been
further proved that the spinal cord of these rabbits con-
tains the rabic poison throughout its whole extent.

If now the cord is cut up into fragments a few ctm. in
length, and if these are hung up in dry air, the viru-
lence gradually disappears; the length of time which
elapses before complete disappearance of the virulence
varies with the thickness of the fragments, and above all
with the external temperature ; the lower the tempera-
ture, the longer is the virulence retained. If the pieces
are preserved in a vessel from which air is excluded, or
in carbonic acid gas, or in a moist condition, the viru-
lence is retained for months, always provided that the
access of saprophytic bacteria is prevented. — In order to
obtain rabic poison of varying virulence suitable for
protective inoculations a number of pieces of cord are
placed at the same time in a corresponding number of
vessels, the air of which is kept dry by pieces of potash.
The portions of cord which are kept in this manner for
one to two days set up, like the fresh material, rabies in
rabbits after seven days' incubation; when the pieces
are preserved for six days the length of the incubation
period is increased to fourteen days ; when the pieces are
kept for seven days in the dry air rabbits inoculated no
longer become ill.

Definite facts as to the active agents are as yet want-
ing, nor do we yet possess a sufficient explanation of the

662 CONDITIONS AFFECTING THE DEATH OF FUNGI.

mode of action. Pasteur has only been able to give
a series of hypotheses, which at the most show how,
with the help of vague speculations, this ingenious in-
vestigator is able to obtain great experimental results.

III. — Means for Killing Bacteria.

Means for The means which are suitable for the destruction of

bacteria. the lower fungi have a special interest, because in the
practical work of disinfection the problem is usually how
to injure the infective agents so that they can no longer
grow and multiply even under the most favourable con-
ditions of existence.
c?£Snuedi Death of the bacteria occurs in the first place when the

withdrawal of

nutriment. exhaustion of the nutrient materials, or the withdrawal
of some material important for life and the consequent
state of latent life, are continued for too long a time.
The death of the individuals ultimately follows the pre-
vention of their development, but the period of time at
which this effect is produced varies greatly according to
the resisting power of the individual species of bacteria.
The spores of bacilli are the most resistant, and may
probably survive in a latent state for hundreds of years;
non-spore-bearing bacilli and micrococci, and more espe-
cially numerous parasitic fungi, are the most sensitive
in this respect.

Withdrawal The withdrawal of water plays a particularly impor-
tant part. This mode of destruction occurs very widely
in nature, and all those bacteria which do not form
resting spores die in a relatively short period of
time. The marked difference in the length of time
during which non-spore-bearing bacteria, and those pro-
vided with spores, can resist the action of drying is a
very useful criterion as to whether any doubtful morpho-
logical structure is, or is not, a spore (pp. 428 and 406).
Spirilla and some species of cocci (streptococci) appear to
be the most sensitive to drying. Differences also exist
between the resting forms of various species, but these
differences have not as yet been accurately made out.

MEANS FOR KILLING BACTERIA. 663

The other conditions of life of the bacteria do not
produce any such marked effect. Pressure and elec-
tricity only appear to destroy bacteria when carried to
extremes (p. 535) ; intense sunlight is said to have a
comparatively energetic action, but these experiments
must be repeated with more careful attention to the
possibility of other hurtful factors coming into play.

A very active agent for the destruction of the lower High tempera-
fungi is high temperature, while, on the other hand, low
temperatures, even carried to an extreme degree, only
prevent development, but never cause the death of
the organism. The effect of heat depends on the
degree of temperature, and on its duration ; con-
tinued action of relatively low temperatures produces
the same result as a short action of high temperatures.
The temperature necessary to cause the death of the Varying
organisms varies also very greatly according to the other
couditions of life, and more especially according to the
resisting power of the species in question. The chief of spores,
difference is found between bacteria which do not form
spores and those which are spore-bearing. — The former
are, as a rule, killed when in a moist state or in fluids by
exposure for one to two hours to a temperature of 48° to
60° C. ; where they are dry the temperature must as a
rule be continued for a longer time. Even spore-form-
ing bacteria may be killed by these relatively low
degrees of temperature if the heat is applied on repeated
occasions, and if in the intervals between its applica-
tion the organisms are placed under the most favour-
able conditions of existence, so that any spores that are
present may sprout and form bacilli. — If the latter are
killed by the subsequent application of heat before new
spores are formed, we may be certain that after the
heat has been applied five or six times no living spores
exist, and all the adult organisms are destroyed. For
example, blood serum may be freed from all organisms,
although the heat employed has not been sufficient to
cause coagulation of the albumen ; the material is placed
for an hour daily for five or six days in succession at a
temperature of about 56° C., and is in this way com-

664 CONDITIONS AFFECTING THE DEATH OF FUNGI.

pletely freed from all living organisms. — It is much,
more difficult to kill quickly the spores of the mould
fungi. Hot air at a temperature of 120° C. does not com-
pletely destroy them after half an hour's exposure ; they
are not certainly killed unless they are exposed to a tem-
perature of 110° to 115° C. for an hour and a half. The
spores of penicillium appear to be less resistant than the
spores of Aspergillus niger. — The most difficult to kill
are the spores of bacilli, although among these great
differences exist. Thus anthrax spores are less resistant
than the spores of tuhercle bacilli, and these again are-
less resistant than those of bacillus subtilis, and more
especially of the bacilli contained in garden earth,
influence of In the process of disinfection it is very important to

moisture. 1,1,1 , -"-,-,

remember that dry spores always require much longer
exposure to heat than spores in a moist state. It
appears as if that total alteration of the protoplasm
which leads to death occurs much more readily when
there is a certain amount of water in it than when it is
completely dry. Hence it is very difficult to destroy
the spores of bacilli by hot air ; even when a consider-
able amount of watery vapour is added to air kept at a
temperature of 100° to 140° C. it acts to a large extent
as a drying medium, and objects exposed to it rapidly
pass into such a state of dryness that it is only with
great difficulty that alterations of the protoplasm occur.
Thus the dry spores of bacilli are only killed by exposure
for three hours to a temperature of 140° C. If it is.
desired to disinfect the interior of large masses which
are bad conductors of heat, a much longer duration of
the heat is necessary in order to obtain the desired
effect. But even an exposure for three hours to 140° C.
irreparably spoils all sorts of clothing.
Action of heat it is much more easy to destroy the spores of bacilli

in fluids. . J r .

in fluids. Anthrax spores are destroyed in boiling
water - ithin two minutes ; the spores of the hay
bacillus resist this temperature for about ten or fifteen,
minutes (according to Buchner for sixty minutes) ; after
fifteen minutes the majority of spores are destroyed.
It is, however, often difficult to raise the temperature

MEANS FOR KILLING BACTERIA. 665

of the whole mass of fluid to be disinfected to 100° C. ;
on the other hand it is easy, as Koch has shown, by
means of a current of steam to obtain the necessary
temperature of 100° C. in all sorts of materials. At the Action of a
bottom of the apparatus necessary for this purpose stoX1mn
there is a large vessel, on the top of which a tube of
sheet zinc, 1 to 2 metres in height, is fixed ; this tube
is gradually narrowed at the top, and finally runs out
in the form of a short tube, only 1 cm. in diameter.
The zinc tube is fixed tightly on the top of the boiler,
and its outer surface is enveloped in some substance
which conducts heat badly. If the water in the boiler
is boiled, the steam passes out of the narrow upper
opening in a strong current, and from that opening
downwards the steam has a temperature of 100° C. If
now the objects to be disinfected are placed inside the
vertical tube they are rapidly penetrated by the steam
and raised to a temperature of 100°, and even in a few
minutes the majority of the spores of bacilli are
destroyed. The duration of the heat must of course be
somewhat varied according to the nature of the materials.
Fresh tubercular sputum is disinfected with certainty in
about fifteen minutes, dried sputum in thirty to sixty
minutes. A duration of sixty minutes is sufficient to
kill the most resistant spores as yet known, even when
surrounded by a relatively dense mass of material. — The
rapidity of the effect is increased by employing a salt
solution, and thus obtaining steam at a higher tempera-
ture than 100° C.

A number of chemical poisons are also suitable for the Chemical
destruction of bacteria. With regard to these, we have p(
to note the concentration of the poison, the duration of
its action, the nature of the nutrient substrata and the
other conditions of life, and the specific resisting power of
the species, more especially the presence of resting forms.
— Bacteria free from spores are on the whole destroyed
by very small proportions ; thus carbolic acid kills an-
thrax bacilli when in a concentration of '25 to '5 per
cent. ; 1 per cent, sulphurous acid kills them within five
to fifteen minutes. — In the practical work of disinfection

666 CONDITIONS AFFECTING THE DEATH OF FUNGI.

Trustworthy
disinfecting
means must
destroy
spores.

Experiments
with anthrax
spores.

a knowledge of the proportions necessary for destroying
bacteria free from spores is of comparatively little
importance ; in many cases we have to do with infective
agents which undoubtedly form spores, in other cases
the infective agents are not accurately known, and the
possibility of the formation of resting forms is doubtful.
Complete trust can therefore only be placed in those
methods which can destroy any spores which may pos-
sibly be present. It is therefore of chief practical
importance to test the disinfecting media with regard to
their action on spores.

In this respect a series of experiments made by Koch is
worthy of note, these experiments having been made by
the comparison of various chemical poisons as regards
their action on the same object — for example, on anthrax
spores. The following are the most important results
of these experiments : —

1. The following substances had no action on anthrax
spores, even after acting for several months : —

Distilled water

Absolute alcohol

Chloroform

Glycerine

Benzole

Benzoic acid (concentrated watery solution)

Salicylic acid (5 per cent, in alcohol, 2 per cent, in oil)

Thymol (5 per cent, in alcohol)

Ammonia

Salt solution (concentrated)

Chloride of calcium solution (concentrated)

Chlorate of potash (5 per cent, in water)

Alum (4 per cent, in water)

Borax (5 per cent, in water)

Potash soap (2 per cent, in water).

2. The following showed incomplete or slow action
on anthrax spores : —

Ether (incomplete action after eight days, complete

action after thirty days)
Acetone (incomplete after five days)
Iodine, 1 per cent, in alcohol (incomplete after one day)

MEANS FOR KILLING BACTERIA. 667

Sulphuric acid, 1 per cent, in water (incomplete after

ten days)
Sulphate of copper, 5 per cent, in water (incomplete

after five days)
Boracic acid, saturated watery solution (incomplete

after six days)
Hydrochloric acid, 2 per cent, in water (complete after

ten days)
Arsenious acid, 1 per thousand in water (complete

after ten days)
Sulphuretted hydrogen in water (incomplete after

five days)

Ammonium sulphide (complete after five days)
Formic acid, 1'12 specific gravity (complete on the

fourth day)
Quinine, 2 per cent, in water (§) and alcohol (;}•)

(incomplete on the first day)
Quinine, 1 per cent, in water with hydrochloric acid

(complete on the tenth day)
Oil of turpentine (incomplete on the first day, complete

after five days)
Chloride of lime, 5 per cent, in water (incomplete on

the first and second day, complete after five days)
Chloride of iron, 5 per cent, in water (incomplete on

the second day, complete after six days)
3. The following showed rapid and complete action,
all of them destroying the organisms on the first day : —
Chlorine water freshly prepared
Bromine, 2 per cent, in water
Iodine water

Osmic acid, 1 per cent, in water.
Permanganate of potash, 5 per cent, in water
Bichloride of mercury, 1 to 20,000 in water
A 5 per cent, watery solution of carbolic acid caused

complete destruction of spores between the first

and second day ; a 5 per cent, solution in oil or

alcohol had no action on anthrax spores.

We may also mention a series of experiments by Effect of a
Gartner and Plagge* which are more especially of carboilflck

* Verhandl. der Deutschen Gesellsch.f. Chirurgie, 1885. or sublimate

668 CONDITIONS AFFECTING THE DEATH OF FUNGI.

practical interest to the surgeon. Gartner and Plagge
employed carbolic acid in the strength of 1 per cent.,
2 per cent., and 3 per cent., and also 1 to 1,000 sub-
limate solution. The materials used for the research
were pure cultivations in meat infusion of the following
organisms : 1. Non-spore-bearing anthrax bacilli ; 2.
Glanders bacilli ; 3. Streptococci from a case of puer-
peral fever; 4. Pyogenic streptococci; 5. Erysipelas
cocci ; 6. Micrococcus tetragenus ; 7. The bacilli of
diphtheria ; 8. Staphylococcus albus ; 9. Staphylococcus
aureus; 10. The cocci of osteomyelitis; 11. Bacillus
prodigiosus ; 12. Bacillus of typhoid fever free from
spores ; 13. Micro-organisms from a case of spontaneous
meningitis. The cultivations were mixed with the dis-
infecting fluids for only a very short time — as a rule
eight to sixty seconds — and a small quantity was then
introduced into nutrient jelly or blood serum. — It was
found that the sublimate solution killed all these
organisms even in eight seconds, with the single excep-
tion of the meningitis organisms, which were still living
after sixty seconds. The 3 per cent, carbolic acid killed
all the organisms without exception in eight seconds.
In the case of the 2 per cent, carbolic acid the osteomye-
litis and the meningitis bacteria required thirty to forty-
five seconds ; with the 1 per cent, carbolic acid rapid
disinfection was only obtained in the case of the anthrax
and glanders bacilli.

As regards the disinfecting action of certain chemical
poisons a large number of experiments have been made
which we need not here refer to in detail, but the
following materials which are much employed may be
mentioned : —

Action of Sulphurous acid was formerly recommended as a

acid. U good and cheap means of disinfection for dwelling-rooms.

20 grammes of roll sulphur were burned per cubic centi-
metre of space ; in order to render the burning of the
sulphur easier 100 ctm. of sulphur matches and 40 ctm.
of spirit were added to every kilo of sulphur. In
this way an amount of sulphurous acid was obtained
representing 1*4 per cent, in volume. The duration of

MEANS FOR KILLING BACTERIA. 669

the action was at least eight hours. — More recent
investigations by Koch and Wolffhiigel have however
shown that sulphurous acid, even when as concentrated
as possible — a degree of concentration which cannot be
attained in practice — only kills spores imperfectly ; even
with regard to non-spore-bearing bacteria the action is
uncertain when present in 10 per cent, by volume if the
layers to be disinfected are at all thick. — Further,
sulphurous acid penetrates with considerable difficulty
into the deeper layers of masses of clothing, &c., and
only has a certain amount of disinfecting action when
the objects have been previously moistened, while at the
same time it causes considerable injury to them. —
Dujardin-Beaumetz has recently again recommended
sulphurous acid, and asserts, as the result of practical
experience and of experiments with cultivations of
bacteria in infusions, that the burning of 20 grammes
of sulphur per cubic metre is sufficient for complete
disinfection. The experimental proofs brought forward
by Dujardin are, however, quite insufficient.

Chlorine and bromine have, on the whole, a very Action of
marked action, more especially when the objects have bromine .an
been moistened, or when the air is saturated with
moisture. In dry air, and where the material is dry,
even several parts per 100 of these vapours in the air
do not cause complete disinfection. Where, however,
the materials have been previously artificially moistened
the presence of '3 per cent, by volume of chlorine and
'21 per cent, of bromine when acting for three hours is
sufficient to kill all spores ; *03 to *04 per cent, by volume
also suffices when it acts for twenty-four hours. This
favourable effect has, however, only been obtained in
experiments in laboratories, and not where the experi-
ments were carried on on a larger scale, e.g., in dwelling-
rooms. In the latter case it is very difficult to keep up
the necessary concentration, and to have the vapour
equally divided through the whole^room.

In disinfection with chlorine it is best to employ for
every cubic metre of space '25 kilo of chloride of lime
-f "35 kilo of crude hydrochloric acid. The material is

670 CONDITIONS AFFECTING THE DEATH OF FUNGI.

divided into portions of at most half a kilo in each
vessel, and these vessels are placed at as great a height
as possible, and at regular intervals. In order to pro-
tect the individual engaged in the experiment care must
be taken that the chief mass of the hydrochloric acid
does not gain access to the chloride of lime till the
room has been closed. In this way 1 per cent, per
volume of chlorine is obtained at first, but the propor-
tion very rapidly diminishes. Spores which are exposed
on free surfaces are killed pretty certainly, but if they
are surrounded by various layers of material the result
is doubtful. By this method, however, all sorts of
materials are irreparably damaged.

Bromine is best employed in the form of masses of
silex, impregnated with definite quantities of bromine,
as recommended by Frank. These masses are placed
at the highest points of the room to be disinfected.
According to Frank, 4 grammes of bromine per cubic
metre are sufficient for complete disinfection, if the tem-
perature is kept uniformly at at least 18° C. According to
Fischer and Proskauer, the distribution of the bromine
in the room is still more unequal than that of chlorine,
and hence the disinfection is correspondingly more uncer-
tain. These experiments were, however, made at a low
temperature, and this probably favoured an unequal
distribution. Sufficient proof is still wanting that at
higher temperatures a really trustworthy disinfection is
obtained at all parts of the room. The injury to the
materials b}7 bromine is at least as great as by chlorine.

Corrosive sublimate is, as is evident from the preced-
ing figures, the most active bacterial poison. A solution
of 1 to 5,000 kills all spores in the course of some hours;
a solution of 1 to 1,000 has the same effect in a few
minutes. As such a solution can be scarcely called
poisonous to man, it is the best means for the disinfec-
tion of the hands and of numerous articles in common
use. It must be noted, however, that in the case of
many substrata, for example albuminous fluids, the
action may not occur, because the sublimate is precipi-
tated, and a sufficient quantity does not remain in solu-

MEANS FOR KILLING BACTERIA. 671

tion ; for example, the addition of sublimate to tubercular
sputum has proved to be quite insufficient for disinfec-
tion. Sublimate has been recommended by Konig* for
the disinfection of dwelling-rooms in the form of vapour,
obtained by heating about 60 grammes of sublimate for
a room of about 60 cubic metre space. It has, however,
been shown by Liibbert,t Heraeus,j and Kreibohm§
that it is only the bacteria which are superficially placed
that are reached and killed by the sublimate, while on
the other hand the very slightest covering of the objects
hinders disinfection.

Carbolic acid is likewise a certain means of disinfec- Action of
tion when in strong solution, and when allowed to act carbohc acul-
for a considerable time ; 5 per cent, watery solutions
destroy resistant spores in a few days. Non-spore-
bearing bacteria are killed by 3 per cent, solutions in a
very short time (see the experiments by Gartner and
Schotte, mentioned above). Carbolic acid often acts
better than sublimate for the disinfection of albuminous
fluids, more especially of fresh tubercular sputum which
is disinfected with certainty in twenty-four hours by the
addition of an equal quantity of 5 per cent, carbolic acid.

As regards the methods of disinfection which should
be employed in practice, see Part VII.

* Centralblf. Chirurg., 1855, Nr. 12.

f Miinchen drztl. Intelligenzbl, 1885, Nr. 49.

I Zeitschr. f. Byg., vol. i., Part 2. § Ibid.

672

APPENDIX.

CONSTANCY AND MUTABILITY OF THE SPECIES OF FUNGI.

Are there SPECIAL importance has recently been attached to the
tion whether the species and varieties of the lower
» which have as yet been looked on as distinct, are

chracters for really of constantly distinct form and possess constant
species of physiological characters, or whether the morphological
and biological characteristics which are employed for
distinguishing the species are varying and inconstant
attributes, which readily undergo permanent alteration
under the influence of the external conditions of exist-
ence.

For the solution of this question we may possibly

obtain information from comparison with the higher

plants, which form useful analogies as regards the con-

stancy or variability of species and their characteristics.

Behaviour of We cannot, however, come to a true decision by such

organisms. comparison : this can only be arrived at by direct inves-

tigation.

As a matter of fact, it has long been known that a
number of morphological and biological alterations can
be observed in all plants. In the first place, certain
alterations are constantly seen in all normal plants of
the same species ; these belong to the characteristics of
the species, and only complete its special characters.
To this class of alterations belong those which the plants
show at various stages of their growth and development ;
further, the alternation of generation of the fungi, with
its enormous differences in form and physiological cha-
Differences in racters. Where the developmental cycle of a species
development. nas no^ J6^ t>een completely ascertained, it may readily
happen that various developmental forms of the same
species may for a time be looked on as independent

CONSTANCY AND MUTABILITY OF FUNGI. 673

species, till more accurate knowledge of the relations
between them has heen obtained.

Further, some plants show differences in their be-
haviour at times, which may be designated as modifica-
tions, and usually as abnormalities of lesser or greater
degree. These changes are set up by some unusual exter-
nal influence; injuries and mechanical insults, abnormal
nutriment, unfavourable situation, and many other causes
act in this way, either singly or together. The conse- TvTon-
quences are degenerative and involution changes of the abnormalities,
most various kinds visible to the eye, and abnormalities
in their physiological behaviour. The variations in the
percentage of ash in the plants, the ofttimes enormous
accumulation of silicic acid, the pallor of plants when
the nutriment is free from iron, the accumulation of
amides in starving flowering plants, the paler colours of
many flowers, and so on, are alterations of this kind set
up by external conditions. But it is characteristic with
regard to these alterations that they are inconstant and
non-hereditary attributes of the plants ; they only last so
long as the external conditions which produce them are
in action, and they disappear after a few generations if
completely normal conditions have been present. These
modifications are thus so variable that they cannot serve
for the formation of new species, for which, on the con-
trary, constant characters, which are transmissible through
a long series of generations, are necessary.

In the third place, however, it must be admitted that
the characters of the species which appear to us as con-
stant may undergo a change after the lapse of a consider-
able period of time. Among many similar plants exposed
to the same external conditions some individuals at
times show slight differences'; the subsequent genera-
tions of these plants retain these differences ; after a
considerable time fresh differences may be observed
among some of the descendants, and in this way we
have a gradual formation of new varieties and species.
This ultimate result is attained either when the varia- Mode of origin
tions are of such a kind that the plants affected by them
grow more strongly and more quickly under the ordinary

43

CONSTANCY AND MUTABILITY OF FUNGI.

external conditions than the other more normal examples,
or when the cultivator intentionally selects the individuals
which show a certain kind of abnormality, and only employs
these for further cultivation.

In this way, Darwin's hypothesis seeks to explain the
origin of varieties, species, and genera. But it is im-
portant and necessary for the definition of a well-marked
species that the new properties should be relatively con-
stant, and not undergo alteration, under the influence of
The varieties varying external conditions. As a matter of fact it seems
duced byr° to be impossible, by selecting the external conditions, to
external con- produce other species at will ; in experiments per-
formed with this aim the plants always remain the
same, they at most undergo modifications and degenerate,
but they do not acquire any constant and hereditary
abnormalities, provided that there is no tendency to
abnormal growth in the plants themselves. The origin
of all varieties may be referred to a tendency in the
plants towards variation which is peculiar to them and
cannot as yet be explained. This tendency is of very
varying intensity according to the species of plant; some
form varieties extremely readily, others extremely seldom,
and the variations occur quite as well when the plants
are all kept under conditions which are as much as
possible the same as when they are subjected to different
influences. It is only the vital power and the power of
development of the varying plants that depends on the
sum total of the external conditions. — Of the most
marked influence on the tendency to variation is the
sexual union of different individuals ; where such a union
occurs variations are usually formed very plentifully.
But even without sexual processes the tendency of many
plants to form new varieties is very great.

Conclusions If now we attempt from these views as to the origin
ap0pHeTto°tL and characteristics of the species of the higher plants,

lower fungi, which have been put forward more especially by Nageli,
to obtain a standpoint to explain corresponding variations
in the lower fungi, we must assume that in these the
formation of modifications, varieties, and species must
as a whole occur in a similar manner. Certain altera-

CONSTANCY AND MUTABILITY OF FUNGI. 675

tions in form can only be looked on as stages in the
development of the same species, and belong within the
boundaries of the species ; further, temporary modifica-
tions will arise under the action of definite external
influences ; finally, varieties and new species with con-
stant hereditary characteristics may be formed from
existing species. To what extent the formation of
varieties occurs will probably depend on the tendency of
the lower fungi to undergo variation ; whether this is
great or small can only be decided by direct observations.
As in the case of the lower fungi, and more especially in
the bacteria, sexual processes are absent, and thus one
of the most important factors in the formation of varieties
is wanting, we must a priori expect a greater constancy
in the species, and a slower variation. On the other
hand, the rapid growth and the quick succession of new
generations can lead to more rapid occurrence of varia-
tions than in the higher plants, and to their formation
within measurable periods of time, and, as it were,
before our eyes. Nevertheless, it is a question how we
should define the individual generations of the fungi.
Is every bacteric cell to be regarded as an individual,
and does each individual colony represent an innumer-
able number of generations, or are the cells of such a
colony analogous to those of higher plants, and is it
only when fructification and spore formation occurs that
a new generation is formed ?

We thus obtain only a number of open questions, and Results of
arrive at the conviction that from the analogy with the Ration °bser~
higher plants we cannot gain any definite conclusions
as to the behaviour of the lower fungi ; hence it is only
by actual observations and experiments that we can hope
for a definite result.

In so far as observations have gone, we have in the i. Morpho-
first place observed all sorts of morphological differences J^e* * dlffer"
in the lower fungi. Some of these differences un-
doubtedly belong to those which only help to characterise
the species. In this sense the processes of growth and
development occasion certain alterations in form which
are always the same in the same species. We observe

676 CONSTANCY AND MUTABILITY OF FUNGI.

that from the most simple spore-cells rods and threads
proceed, and that spores again form in these threads ;

Stages of we observe, further, in the mould fungi, such as asper-
gillus or penicillium, a transition into a completely
different form of fructification — we see the ordinary yeast
pass into spore-bearing cells of a totally different form.
External influences often lead to the formation of the
one or the other form of development ; but under these
circumstances there always arise only the definite forms
which are characteristic of the species, and not all sorts
of variations differing according to the external con-
ditions which have been at work. According to Zopf 's
views there is in the case of many bacteria a particularly
wide cycle of vegetative forms ; but in spite of all these
differences in form definite species can nevertheless be
made. We have only, in this respect, to learn all the
stages of development, and to arrange them among the
characteristics of the species.

Degenerative In the second place, in the lower fungi modifications of

modifications form also occur under the influence of external agencies.

according to T^ & certajn degree the nutrient conditions, for example,

nutriment. . ...

can influence the form in a similar manner as in the case
of higher beings. Slight increase or diminution in length
and thickness, a more marked swelling of the cells and
threads, is not uncommonly observed (Buchner) ; and
according to the external conditions of existence, now the
one, now the other stage of development may be most
prominent, and may be observed in a particularly com-
plete form. But on more careful examination we can
ascertain that these variations scarcely ever go far
enough to alter the types of form which are looked
on as characteristic of the individual species. The re-
lation of the length of the rod-shaped bacteria to the
breadth, the form of the ends of the rods, the character
of the thread form, the mode in which the individuals
are grouped together, remain, as a whole, untouched by
such variations. Under the practically abnormal ex-
ternal conditions more marked alterations in form, and
the production of pathological and involution forms, often
occur. These variations in form render it difficult to

CONSTANCY AND MUTABILITY OF FUNGI. 677

differentiate the bacteria on the basis of their morpho-
logical characters, more especially as in the case of the
bacteria we have to deal with extremely slight and deli"
cate differences in form ; and hence we must give up the
former classifications based essentially on such differences.
But as a matter of fact these various alterations in form
do not lead to the disappearance of the species, but only
serve, by the use of more complete means of observation,
for a more accurate differentiation of the individual
species.

After the lapse of long periods of time it is probable True varieties
that a third kind of morphological alteration may occur
in the lower fungi, and lead to the formation of varieties
and new species ; these alterations, however, appear as
a rule to occur in a similarly slow and inappreciable
manner as in the higher plants. Very distinct evidence
has recently been produced which shows that the form
of certain bacteria has undergone extraordinarily little
variation even in the course of hundreds and thousands
of years. In thin sections of the petrified roots of coni-
fers from the coal period, van Tieghem* was able to
demonstrate the characteristic butyric acid bacillus;
and Zopf and Miller t found in the tartar on the teeth
of Egyptian mummies the same forms of bacteria which
can at the present time be demonstrated as the ordinary
inhabitants of the mouth. These examples, however,
are only of value for the species in question, and we
cannot without further information draw the conclusion
that all fungi have a similarly slight tendency to undergo
variation.

Nageli, Buchner, Wernich, and others have formerly Differences in

asserted that under the influence of external conditions a *he views as
, , . ,. . p , ,, . . to the van-

very marked variation in torm occurs, and that one species ability of

can be converted by variations in the conditions of its form,
existence into another species, characterised by other mor-
phological characters and other modes of growth (thus the
anthrax bacilli were converted into a so-called transition
form, and then into true hay bacilli, see p. 241). — The

* Compt. rend., 1879. f Arch.f. exp. Pathol. u. Pharm., 1882.

678 CONSTANCY AND MUTABILITY OF FUNGI.

more, however, the methods of pure cultivation have been
perfected, the more has the conviction gained ground that
such variations in their characters probably occurs to as
slight an extent in the case of the bacteria as in that of
higher organisms, and that the former observations on which
these statements were founded were not made by methods
which were free from objection. Buchner himself has in his
more recent investigations pointed out numerous specific
morphological characters. It is no doubt not impossible that
many of the species which have as yet been looked on as
definite forms from examination by incomplete means, and
at an early period of our knowledge, may, when the modes of
investigation have become more perfect, be recognised as
related to each other, and that thus from two species which
have as yet been looked on as morphologically distinct we
may have to form a single species with a somewhat great
variability in vegetative form. But as yet no facts of this
kind have been demonstrated, and if they should be demon-
strated in any individual case they would not afford any
ground for doubting the value of the morphological characters
in distinguishing the species of other bacteria.*

2. Physiologi- In view of the difficulty of the morphological dis-
)es' tinction of species, we must, as has already been men-
tioned above, in many cases employ marked and specific
physiological characters as means of diagnosis and of
classification. The characters so employed must
naturally be constant and hereditary; it is only then

* Buchner has recently (Arch.f. Hyg., vol. iii., p. 380) implied that I
confound variability in vegetative form with that of species, and that
I fight against the former, while in reality I mean the latter. But
from various portions of my criticisms of Zopf's hypothesis, as well as
in the first edition of this book, it is very evident that I am by no
means guilty of any such mistake. As a proof I cite the following
passage from p. 276 of the first edition of this work :—

"In spite of the view that cocci, bacteria, bacilli, spirilla, only
represent developmental forms which readily pass into each other, it
might nevertheless be still possible to form distinct morphologically
characterised species. We observe in the cocci, bacilli, and spirilla,
many other peculiarities of form which might serve to characterise a
species, and if the chief weight were laid on these peculiarities we
would obtain a classification founded on morphological characters, and
could ultimately attempt to make a diagnosis of the species according
to the external form, even though the same fungus occurred in a coccal,
bacteric, or spirillar form."

According to the view which Buchner and Wernich support, such a
differentiation of constant forms would not, however, be trustworthy ;
these morphological characters would, as a rule, only be the product of
the external conditions of life.

CONSTANCY AND MUTABILITY OF FUNGI. 679

that they can be of use for the formation of distinct
varieties. Characters which readily undergo alteration
under the influence of all sorts of external conditions,
which are readily lost and acquired, are as little suitable
for characterising varieties as varying differences in
form.

As a matter of fact we have, in the production of
ferments, in the formation of pigment, in the setting
up of fermentation and disease, and in the whole mode
in which the nutrient substrata are assimilated and
broken up by the bacteria, such hereditary and cha-
racteristic physiological attributes of the species of
bacteria.

It has been already mentioned above (p. 563) that Variability
the sum total of the external conditions of existence of varying1

exerts a very marked influence on the quality of the pro- exte™al
ducts of tissue change, and that by abnormal external
conditions every individual phase of the characteristic
vital phenomena may be abolished ; but, nevertheless,
these variations in physiological characters follow defi-
nite lines and do not go beyond the characters of the
species in question. In correspondence with this fact
those vital phenomena which are constant under certain
nutrient conditions can be very readily employed as
means of distinction ; and the loss of the individual
characters as the result of definite external conditions
only serves as a means of increasing the number of
characteristics of the species.

Further, as in the case of other organisms, so also Alteration by
probably in the case of bacteria, they may become accli- tioV.™
matised to abnormal conditions of existence; for example,
to an excess of salts, to a different reaction of the nutrient
medium, to temperature, &c. It is conceivable that
the same abnormal conditions when suddenly employed
cause cessation of development, while when gradually
introduced they still permit the exercise of the vital
functions. More accurate facts, however, are still want-
ing as to the behaviour of bacteria under such conditions,
but it is a priori probable, from what we know of the
behaviour of the higher organisms, that even under

680 CONSTANCY AND MUTABILITY OF FUNGI.

suitable acclimatisation of bacteria the result will be
not a loss or diminution, but a multiplication of their
specific characters, and that the properties thus acquired
will again be lost after a few generations when the
abnormal external conditions are replaced by normal
ones.

Niigeli's views Nageli, Buchner, Wernich, and others have formerly assumed

as to the ^e existence of a very rapid and limitless alteration of the

mutability or , „ •/. -i • -i ••,-,-,

the bacteria, characters ot species of bacteria which had up to that time

been distinguished from each other. " According to my view
each of the species of bacteria could occasion the formation
of lactic acid, putrefaction, and various forms of disease.
Each species has the power of accommodating itself to un-
equal external conditions, and consequently of appearing in
various forms morphologically and physiologically peculiar.
The adaptation or acclimatisation may be more or less com-
plete and more or less permanent, according to the time and
the other factors which are at work. . . . Thus forms of an
unequal degree of development and of unequal constancy-
would be produced in accordance with the various external
conditions. The same bacterium would at one time live in
milk and form lactic acid ; at another on meat and cause
putrefaction ; again in wine, and lead to the formation of a
gummy substance ; subsequently in the earth without setting-
up any fermentation ; and finally in the human body, and take
part in some form of disease. ... It would on a soil which
was equally disposed for various fermentations occasion those
changes which most correspond to the physiological stage at
which it has arrived by its previous mode of life. Bacteria
which frequently change their habitat would of course retain
an indefinite character, and be equally well disposed to
assume different forms and to excite different fermentations "
(Nageli*).

Nageli and Buchner found an experimental support for
these views in the observation that bacteria which caused
milk to become sour lost this property in a saccharine solu-
tion of meat extract, and caused there an ammoniacal fermen-
tation, and it was only after a hundred or more generations
in milk that the property of forming acid slowly recurred.

Hueppe, however, tested this question accurately, and was
unable to make out any such variability in the behaviour of
the lactic acid bacilli, but he showed that an ammoniacal
fermentation could be caused in the milk by butyric acid
bacilli, which, in the form of resistant spores, could readily

* Niigeli die niederen Pibe, Miinchen, 1877, p. 22.

CONSTANCY AND MUTABILITY OF FUNGI. 681

remain unnoticed in a living condition in milk which had
been insufficiently sterilised ; and thus he showed that it was
probable that in these experiments we did not have to do with
variation in the characters of the same species, but with the
effect of different species of bacteria.

The more the methods of pure cultivation of bacteria have
been improved, and the more complete our knowledge as to
the biology of the bacteria has become, so much the more
certainly do all other experiments' lead us to the conviction
that the specific vital characters of the lower fungi can be
retained in a similar manner as in the higher organisms, and
are not subject to any extensive variation. — Even Buchner
in his more recent investigations recognises the physiological
attributes of the bacteria as sufficiently constant to enable
him to base on them a distinction between the individual
species.

It is true that during a long period of time, just Formation of
as in the case of the higher plants, a real formation of van'
varieties may occur in the lower fungi, the physiological
characters being chiefly affected. This variation does
not, however, arise as the direct result of definite ex-
ternal conditions, but is due originally to a certain
tendency to variation which often only leads to an
ephemeral existence of the somewhat abnormal ex-
amples, and thus to no important consequences ; at
times, however, when by chance the external conditions
are such tbat these abnormal examples are, as the result
of the abnormality in their physiological characters,
especially able to grow concurrently with other organ-
isms, and are not weaker than individuals which have
not these properties, we may have a continuation of
these abnormalities through a series of generations, and
thus the formation of a new variety. In many of the
lower fungi, however, the tendency to this form of
variation is extremely slight ; more especially we must
accept it as undoubted with regard to most of the ex-
citing agents of fermentation that they have retained
the same physiological characters and the same mode
of breaking up the fermenting materials for thousands
of years.

In one respect, it is true, a character of the bacteria
has been observed which does not apparently follow the

682

CONSTANCY AND MUTABILITY OF FUNGI.

The loss of
the power of
bacteria to
excite disease
and fermenta-
tion.

It would be
necessary to
regard attenu-
ation as a
degenerative
process if it
were not
hereditary.

laws which have heen made out with regard to the higher
organisms. The power possessed by many "bacteria of
multiplying in the body of living warm-blooded animals,
as well as the property of others of exciting fermenta-
tion in suitable substrata, have, as has been above men-
tioned (p. 656), proved extremely labile in many species
of bacteria, and can be destroyed by numerous in-
fluences, such as high temperatures, chemical poisons,
&c., which cause degeneration of the organisms. In-
deed, the repeated passage of certain parasitic bacteria
through more or less suitable hosts appears, according
to Pasteur's experiments, to lead to increase or diminu-
tion in their virulence,* and in the case of glanders, for
example, a cultivation for a certain length of time on
potatoes, which is otherwise the most suitable dead
nutrient material for their growth, suffices to lead to
complete disappearance of their virulence (Loeffler).

This "attenuation" of the lower fungi would not be of
much importance if we had only to do with a degenera-
tive process which had arisen under the influence of the
abnormal conditions of life employed, and which was
only retained so long as these conditions acted, and
was not hereditary through a long series of genera-
tions under normal conditions, but was rapidly lost.

* A similar alteration of pathogenic properties of the lower organisms
TOas formerly stated to occur by Davaine as the result of his experi-
ments on progressive virulence. Davaine thought that he had observed
that the virulence of septicaemia bacilli constantly increases the oftener
they are inoculated from one animal to another; thus, while of an
infective fluid found accidentally several drops are necessary to insure
infection in the first instance, yet, when it has been inoculated from
animal to animal for a considerable time it is ultimately found that the
minutest fraction of a drop is sufficient to cause the fatal disease.
Koch and Gaffky (Mittheil. a. d. Kais. Ges. Ami., vol i.) were able to
demonstrate that in the case of several bacteria which occasioned
septicaemia no such progressive increase in virulence existed ; that it
was only necessary to employ larger doses at first, when the material
used for inoculation was very impure and only contained a few of the
pathogenic organisms ; that, on the other hand, when the material was
pure the same dilution was as active at the commencement of the series
of experiments as at the end. More recent experiments of Pasteur as
regards swine erysipelas, hydrophobia, &c., point, however, to the fact
that some species of bacteria undergo marked alterations in virulence
as the result of their passage through the bodies of certain warm-
blooded animals.

CONSTANCY AND MUTABILITY OF FUNGI. 683

In this case the attenuation would be analogous to the
numerous degenerative processes which have heen ob-
served in higher organisms ; the diminution in the
amount of quinine in the species of cinchona, the loss
of the production of conium in hemlock when the plants
are cultivated in unsuitable soil, the diminution in the
amount of chlorophyll, or the imperfect and slower
growth of the various organisms under unfavourable
external conditions, would then furnish analogous ex-
amples.

But it is remarkable that the attenuated condition of An attenuated
pathogenic and fermentative bacteria cannot as a matter however? 1S

of fact be removed, as in the case of these degenerated t0
plants, by subsequent cultivation under normal condi- generations.
tions. On the contrary, undoubted facts have been
made out which show that this attenuated condition
can last for a long time, and through a long series
of generations, more especially when it was set up by
milder means, employed for a long time.

Thus in the case of many bacteria a character has
been made out which must be regarded as a biological
curiosity, and which does not in any way harmonise
with the other biological characters of the bacteria. For Thus a
on the whole we undoubtedly observe, as has been stated chaSTr has
above, a constancy in the hereditary properties of the ^en Provf^
bacteria similar to that of the higher plants, and even the bacteria
the virulence of the parasitic bacteria appears to corre- Entirely ^rom
spond in its laws with those of the other characters, in ^aj of the

. ... . higher organ-

that in spite of numerous variations in the cultivation, no isms.
alteration occurs, or only appears under certain abnormal
conditions, and then affects the one generation alone.

There can, however, be no longer any doubt as to the
remarkable fact of the artificial development of a here-
ditary attenuated condition in some bacteria, and as the
result of this most recent development of our know-
ledge, we must come to the conclusion that we ought to
be extremely cautious in our judgment when we attempt
to apply laws which concern other organisms to bacteria,
or when we would draw general conclusions with regard
to bacteria from single observations.

084 CONSTANCY AND MUTABILITY OF FUNGI.

More than in any other scientific department is it
necessary to limit our judgment in the case of the lower
fungi to the particular species in question, and we are
just as little justified in declaring that a hereditary
attenuated condition of the hacteria is impossible, as
the result of theoretical considerations, as we would be
in deducing from a few instances in which such attenua-
tion has been proved that there is an extensive altera-
tion of virulence as the result of other influences, and
in the case of other species of bacteria, which have not
been tested, or that there is a similar variable condition
of all the other properties of the bacteria.

685

PAKT VI.

DISTRIBUTION AND HABITAT OF THE BACTERIA.

NUMEROUS forms of bacteria grow in the most various General
surroundings of mankind, whenever they meet with Of&the u
sufficient moisture, nutritive material, and a temperature bacteria-
of at least 6° to 10° C., and they multiply the more
quickly the nearer the temperature approaches the aver-
age optimum of 20° to 30° C., and the better and more
plentiful the nutritive material. Wherever dead organic
materials, excreta of man and animals, dead bodies, dead
plants, household refuse, &c., accumulate on the surface
of the ground, in stagnant or running water, or within
dwelling-houses, in the presence of sufficient moisture
and temperature, bacterial growth occurs, and ultimately
occasions the complete destruction of these materials,
the place of which is taken by an enormous number of
newly-formed individuals.

In view of the distribution, the enormous capacity for
multiplication, and the relatively great resisting power of
the bacteria, one involuntarily inquires as to the means
which come into play in nature in order to destroy the
masses of bacteria which are being constantly formed,
and to provide against their accumulation in too great
numbers. The cold of winter is not the active agent,
for, as is well known, it only occasions an arrest of de-
velopment, and appears to preserve all the bacteria in a
living state. The natural means of disinfection is in The natural
the first place drying of the bacteria ; then exhaustion of SaSection.
the nutritive substrata ; at times also high temperatures,
more especially on the surface of the soil from the solar
heat. These various agents in truth only kill the less
resistant vegetative forms, while the majority of the per-
manent forms retain their vitality in a dry state, and

G86 DISTRIBUTION AND HABITAT OF THE BACTERIA.

also in solutions in which the nutriment is exhausted,
and at the highest temperature reached by insolation at
the surface of the soil.

Nevertheless, the effect of these means may he great,
and indeed sufficient for the purpose, because oppor-
tunities for the sprouting of the spores often present
themselves in nature, and they thus assume a vulnerable
form; and hence it is chiefly by a constant variation
between good nutritive conditions on the one hand, and
the absence of water and nutritive materials on the other,
that destruction of the various kinds of bacteria and
regulation of the bacterial life are brought about.
Fate of In the case of those forms of bacteria which excite our

bacteria. special interest by the fact that they can at times develop
in the bodies of the higher living animals, their continued
existence in our natural surroundings is rendered more
especially difficult, because they are for the most part
very particular as to the quality of their nutriment,
require a favourable temperature, and are often extremely
sensitive to alterations in the nutritive substrata, and to
the amount of water present. Further, all the faculta-
tive parasites are very readily overgrown by saprophytes,
which grow much more quickly under the conditions of
life present in our surroundings; the latter therefore
withdraw from the former the necessary nutritive
materials and also injure them by the products of
their tissue change. If, therefore, it is necessary for
infective agents to grow for a considerable time under
the ordinary conditions, they must evidently have the
opportunity of growing in a sort of pure cultivation ; and
such an exclusive occupation of the substratum by patho-
genic bacteria sometimes occurs on semi-solid nutritive
materials, on floating portions of vegetable or animal
tissue, &c. — In fact the preservation of facultative and
obligatory parasites which have grown in this way out-
side the human body, or which have grown in the human
body, and passed from it into the surrounding world, is
a matter of considerable difficulty. They are most easily
preserved when spore forms are present, which can per-
sist unaltered for a long time in a dry condition, or in

DISTRIBUTION AND HABITAT OF THE BACTERIA. 687

exhausted nutrient material. Where spore forms are
absent, preservation can possibly still occur if the exist-
ing conditions are such that the sensitive parasitic bac-
teria are not destroyed or overgrown by saprophytes.
Conditions of this kind are furnished, for example, where
the temperature is under +5° C.; and also (as will be
described more fully afterwards) in porous and moderately
moist soil.

For the distribution of bacterial life on the surface of Transport of
the soil, it is also of importance that they should not be
restricted to the original place where they developed, but
should be transported over greater or less distances.
Currents of air and flowing water are the most important
means of transport; to a less extent, but in a great
variety of ways, they may also be carried by animals and
by the trade and intercommunication of mankind.

When we examine our various surroundings as to the Occurrence
presence of bacteria, we find them, in the first place, in of bacteria^
the air in very varying numbers. By the methods as the air-
yet emplo}'ed for these investigations, from 100 to 500
living bacteria have been found in every cubic metre of
the layers of the air which lie immediately above the
ground; in the air of dwelling-rooms they have been
found in very small numbers when all movement of the
air has been as much avoided as possible for some time,
while they are present in large numbers when the dust
has been raised by movements and other disturbances.
Direct microscopical examination of the collected air
germs, as well as the experiments on filtration of the air
(Hesse), have shown that the micro-organisms floating
in the air do not occur as isolated individuals, but that
numerous individuals of the same kind are as a rule united
together in chains and groups, or adhere to coarse par-
ticles and visible pieces of dust.

The origin of the air germs must almost always be Origin of air
sought in the bacterial colonies on the surface of the fferms-
earth, for there is not sufficient moisture to permit

688 DISTRIBUTION AND HABITAT OF THE BACTEBIA.

multiplication during their transport through the air.
Further, bacteria as a rule only pass into the air from
bacterial colonies which are thoroughly dry and are
broken into fragments by external force. Nageli has
shown that even strong currents of air are unable to
detach bacteria from moist surfaces ; it is only when
there is at the same time a spurting up of the fluid by
waves, or by violent agitation (mill wheels, washing, &c.),
or by the formation of bubbles, that particles of water,
and with them bacteria, can be carried by currents of air
Only over short distances. Even when a colony of bacteria

drybacteria dries up it cannot at once become loose, so that portions
pass into the C0uld pass into the air ; on the contrary, the dried bac-
teria generally adhere very firmly to the substance beneath,
and it is only by breakage due to external violence, or to
the eifect of temperature, that small light particles are
loosened and can be carried away by currents of air.

Former observers had, it is true, at times obtained evidence
of detachment of bacteria by feeble currents of air, and even
from moist surfaces, but those experiments were not made
with pure cultivations of bacteria, nor by the help of solid
nutrient substrata, and hence bacteria entering through in-
sufficient joints might easily cause deception and lead to the
idea that they had become detached from the surfaces of the
fluids investigated. At the present time the experiments
can be readily repeated with completely uniform results if
we work with pure cultivations of the rarer forms of bacteria
and are thus able to distinguish organisms which have come
accidentally from without, from those which were present on
the surface of the nutrient substrata.

C

Difference in The bacteria, once they have passed into the air, float
or are carried about by currents of air for a varying time.
In addition to differences in the strength of the currents,
the size and weight of the floating particles is of especial
influence in this respect. Gross particles of dust, such
as one sees with the naked eye by any mode of illumina-
tion, soon fall in quiescent air along with the bacteria
adhering to them ; the smaller or so-called solar specks
float more easily, and are carried about by slight
currents. Finally, the minute collections of bacteria or
individual bacteria which are never visible to the naked

DISTRIBUTION AND HABITAT OF THE BACTERIA. 689

eve, and of which the weight represents the billionth of
u gramme or less, do not become deposited to any great
extent even in quiescent air. We must also suppose
that these minute bodies are surrounded by a condensed
coating of air consisting chiefly of the vapour of water,
and forming as it were a parachute and mantle which
renders floating easier (Niigeli).

From these observations and considerations we at Local differ-
once arrive at some laws as to the local and seasonal nnmbe? of"air
distribution of bacteria in the air. Everywhere where germs.
there is a plentiful development of bacteria on the sur-
face of the soil, and where complete dessication of super-
ficial colonies takes place, there will be a considerable
number of bacteria in the air. Where there is no oppor-
tunity for the growth of bacteria (in deserts, on high
mountains, &e.), or where the surface is always moist
(over the sea), the air will be almost or entirely free from
bacteria. Nothing certain is known as to the distances to
which dry but living bacteria can be carried by the wind ;
from the extraordinary distances over which other par-
ticles of dust can be carried, we may conclude that when
opportunity offers the bacteria may be carried over very
considerable areas. This circumstance naturally tends to
destroy to a considerable extent local differences in the
amount of bacteria in the air ; nevertheless, by far the
greater number of the air germs will always originate
from local sources.

It cannot be decided, and it is also of subordinate impor-
tance, whether the few bacteria which have been found on
high mountains have their origin in winds or in the body,
the clothes and utensils of the observers, or in insignificant
local sources ; and of equally slight importance is the hunt
for bacteria in the air of the highest mountains and on the
most distant seas, which has been carried on for the last few
vears, has been entirely wanting in proper aim and has more
reference to the sensational public than to scientific interest.

Variations at different times in the number of air Variations at
germs are, apart from the varying quantity of available
bacterial colonies, dependent in the first place upon the germs,
conditions which favour the passage of new bacteria

44

690 DISTRIBUTION AND HABITAT OF THE BACTERIA.

Influence of
dry winds.

Effect of the
distribution
of the germs
over a great
extent of air.

into the air ; and in the second place upon the factors
which influence the deposit of floating germs from the
air. Dry winds more especially lead to an increase in
the number of bacteria in the air. Even when the de-
ficiency of moisture in the air is not great, and when the
air is moist, drying of the most superficial layers may
occur at the exposed parts of the surface of the earth,
and dust may he carried into the air along with a certain
number of bacteria ; great drought lasting for some time
(as in the case of the east winds in our neighbourhood)
leads, however, to a much greater degree of drying ; every
corner of the streets, courts, and houses, the deeper layers
of the soil, &c., gradually become dry, and many more,
and also greater varieties of, bacteria, — ultimately also
pathogenic bacteria, — pass into the air in these places.

In spite of this markedly favourable influence of dry
winds in increasing the number and kinds of air germs,
it is nevertheless possible that a cubic metre of the air in
our neighbourhood may scarcely show more germs than
in still, damp weather. For the dry winds will possibly
distribute the germs which are taken up over a much
greater area, and more especially carry them to a con-
Deposit of air siderable altitude. A greater amount of water in the

S-ermsbythe , ,. . ,, ,

condensation atmosphere, on the contrary, more especially, however,
vapour * *ne occurrence of descending currents of moist air, and
in particular a great condensation of water vapour, must
lead to sinking of the particles of dust, and thus occasion,
in the first place, an increase in the number of germs in
the layers of air close to the surface of the earth, until
continued condensation and rains have eventually brought
back the greater number of the bacteria to the soil. — In
the investigations made up to the present time, but little
attention has been paid to these conditions affecting the
distribution of the germs in the air, and especially to
the possibility of their deposition by condensation of
water vapour, although it is probable that a more inti-
mate knowledge of the mode of distribution of the air
germs will give us enlightenment as to the mode in which
many infections (e.g., malaria) occur.
Over estima- On the whole too great a role was formerly ascribed to

tron of the J

DISTRIBUTION AND HABITAT OF THE BACTERIA. 691

the air in the spread of saprophytic and infective germs, danger of air
By the experience obtained in bacteriological work and in
surgical practice, it has become evident that bacteria but
seldom enter nutrient substrata from quiescent air, that
even a simple cover which keeps off the vertically falling
particles of dust forms even in impure air an extremely
efficient protection, and that the entrance of bacteria
occurs far more frequently from unclean objects, unin-
tentional contaminations, &c., than from air germs. On
the other hand, dusty air in active movement offers an
excellent opportunity for the spread of bacteria ; and it
is remarkable in what numbers they may be deposited
on a cool object — on nutrient materials, &c., placed in
ice — along with the water vapour condensed at the
same time. But even then the pathogenic bacteria
form only a minute fraction as compared with the sapro-
phytes. In fact in the open air the dilution of the
pathogenic germs soon becomes so very great that a
direct infection is a rare occurrence ; it is only from the
air within dwellings and in the neighbourhood of the sick
that infection occurs at all frequently.

Neither the points of view nor the methods for the in- Defects in the
vestigation of the air are at the present time so precise that investigations
it is possible to make definite statements as to the local on
and seasonal differences in the number of the air germs,
or that well-founded conclusions can be drawn as to the
part played by the air in the spread of one or other of
the infective diseases. Miquel's attempts to draw a
parallel between the results which he has obtained in
his air investigations, and the mortality from the various
infective diseases, are at least premature, and only show
how long-suffering the statistical method is, and hov*
easily it can be misused in order to prove a deceptive
causal connection.

The distribution and behaviour of bacteria in the soil Occurrence
is of very special hygienic interest, because for a long of
time, and especially since Pettenkofer's convincing -de- the soil-
ductions, the soil has been regarded as a very important

692 DISTRIBUTION AND HABITAT OF THE BACTERIA.

factor in the occurrence of epidemic diseases. The
connection proved by statistics to exist between the varia-
tions in the mortality from typhoid fever in Munich and
the variations in the level of the ground water furnished
the chief argument for the view that something took place
in the soil which exercised an important influence on
Pcttoukofer's the spread of a number of infective diseases. The
interesting results of that statistical observation leave it
llowever>in tlie first Place> doubtful whether the alteration
tive bacteria, in the soil, as shown by variations in the ground water,
exercise any influence on the development of the infective
germs ; or whether it is only of special importance for
the transport of the germs present in soil to man ; or
whether, in the third place, there is a direct connection
between the conditions of the soil and the infective
germs, or an indirect one in this way, that the apparently
predisposing condition of the soil and the spread of the
epidemics must be referred to a third causal factor
common to both. — Further, the question arises, sup-
posing that the soil exerts some direct influence on one
or several of the infective agents, whether this influence
must be regarded as absolutely necessary for the epidemic
spread of the diseases in question, so that a necessary and
specific role must be assigned to the soil ; or whether
the spread of the same disease may not frequently occur
in other ways without any connection with the soil ?

The decision of these questions is evidently only
possible when we obtain a more accurate knowledge of
the pathogenic agents, of their vital characters, and of
their mode of spread ; before we possessed any know-
ledge of this kind we could only form hypotheses as to
the more intimate connection between the soil and in-
fective diseases.

View as to a Pettenkofer and his followers formerly sought to show
fluoncc of the *kat ^ was Pr°bable that the soil exercised a peculiar
soil on the and definite influence on the development of the infective

development ., . , .

and spread of germs as well as on their transport to man ; a porous

'tlvc soil infiltrated with waste organic materials and moistened

from time to time was supposed to be indispensable

for the development, and, so to speak, ripening of the

DISTRIBUTION AND HABITAT OF THE BACTERIA. 693

infective agents ; and the same soil was supposed, per-
haps at a definite stage of dryness, to enable the infective
germs to be transported by currents of air.

This view was undoubtedly completely justified by the
state of our knowledge at that time as to the nature of the
pathogenic agents. But since we are now able to set on
foot direct observation and experimental investigations
as to the mode of development and the conditions of
existence of the infective agents, we must subject our
former views as to the occurrence of infective diseases,
and more especially as to the influence of the soil on the
pathogenic bacteria, to revision and criticism. In fact
as to the behaviour of bacteria in the various media in
our surroundings many thorough investigations are
necessary, and we are far from seeing clearly the re-
lations between the soil and the pathogenic bacteria.
But in many directions the more recent bacteriological
investigations have given us valuable facts which compel
us to alter our former views.

If we shortly summarise what we have learned during Results of
the last few years by direct observation and experiment

as to the general behaviour of the most various kinds of jal investiga-

tions of soil.

bacteria in the soil, we obtain in the first place the

unanimous result that, as a matter of fact, the bacterial

life in the soil is extremely active, that the soil is evidently

the chief reservoir for bacteria, into which the greatest part

of all fluids containing bacteria, almost all refuse water,

excreta, &c., pass, and on the surface of which the germs

which have passed into the air are again in great part de-

posited. Enormous numbers of bacteria have always been Richness of

found in the soil by the most various observers. Infusions various kind*

made from manured field and garden earth, even though of bacteria.

diluted 100 times, still contain thousands of bacteria in

every drop, and the ordinary soil of streets and courts also

shows the presence of large numbers. Bacilli are present

in much the largest numbers ; but in the most super-

ficial layers and in moist ground there are also numerous

forms of micrococci. Some species are markedly promi-

nent, and are found in the most varied places and at the

most various times in the soil, while they occur in other

094 DISTRIBUTION AND HABITAT OF THE BACTERIA.

substrata much less commonly; such are, for example,
the bac. mycoides (p. 403), and some other forms which
have not as yet been more minutely described. Various
kinds of bacilli must also be very often present in the
soil in the form of resting spores, as can be concluded
with certainty from disinfection experiments.

Pathogenic Pathogenic forms are also not uncommonly found.

bacteria te Well.known inhabitants of the soil are the bacilli of
malignant oedema, of infective tetanus, the bac. septicus
agrigenus, &c., which are commonly and almost ex-
clusively found in garden or field earth. Pathogenic
bacteria occur with such frequency in the soil that no
material found in nature so easily produces infection as
earth. If mice, guinea-pigs, or rabbits are inoculated
with a quantity (not too small) of earth from the surface
of the ground a much higher percentage of cases of
disease is obtained than when the inoculation is made
with some fluid containing bacteria. If large quantities
of the latter are injected a large number, or it may be
all of the animals die of ptomaine poisoning ; but an

Frequency of infective disease only results in rare cases. We have

action of the also reason to assume that the infective diseases caused
by the soil would be more numerous, and would lead to
the isolation of other species of pathogenic fungi, were
it not that these oedema and tetanus bacilli are so widely
distributed that they obscure the other infective agents
and cause the death of the animal before other moro
slowly growing bacteria have had time to multiply.—
This marked infective property of the soil must evidently
make us a priori inclined to accept the view that the
soil is of special importance in the occurrence of human
infective diseases.

Vital powers We have also obtained some information as to certain

of theSeria effects produced by the bacteria on thesoil. Thus Schlosing
and Miintz, and at a later period Warington, showed that
the formation of nitric acid from the ammonia of organic
substances is chiefly caused by lowly organisms ; when
soil has been heated or treated with disinfecting means
it loses almost entirely this power, which is otherwise
constantly observed. In like manner Wollny and Fodor

DISTRIBUTION AND HABITAT OF THE BACTERIA. 695

were able to show that the formation of carbonic acid in Production of

nitric acid and

the soil was entirely the result of the life of lower organ- carbonic acid,
isms. Further, Gayon and Dupetit, as well as Deherain
and Maquenne, have furnished proof that when oxygen is
deficient a reduction of the nitrates to nitrites, ammonia
and nitrogen can be brought about by the bacteria
of the soil. According to investigations made by Reducing
Heraeus (Zeitschriftf. Hyg., vol. L), many forms of bac-
teria (such as bac. prodigiosus, cheese spirilla, Finkler's
spirilla, typhoid bacilli, anthrax bacilli, staphylococci)
are able to oxidise ammonia to nitric acid ; while other
species (for example, two kinds of bacilli cultivated from
water) cause the reduction of the nitrates in a marked
manner. Schlosing and Miintz held that nitrification was Nitrification

, , , , „ , -1.1 1S n°t caused

caused exclusively by one species of bacteria which was exclusively by
isolated by them from the soil ; but their description of the ]£* ^teria of
bacteria does not at all indicate that they worked with a
really pure cultivation, and the investigations of Heraeus
compel us to adopt the view that a large number of
bacteria are capable of causing nitrification either by
simple assimilation and oxidation, or by a sort of fer-
mentation. In soil the conditions are especially favour- Jut the most

favourable

able for some of these bacteria which act by oxidation conditions for
because concentrated solutions and large quantities of are^rese^tod
organic material further the multiplication of the re- bv the soil-
ducing bacteria, while in more dilute nutrient substrata,
which is usually the condition even of unclean soil, the
oxidising bacteria gain the upper hand. Hence in by far the
greatest number of cases we observe oxidation processes
in the soil, which on account of the marked subdivision
of the material in thin layers, the intimate contact of
air, and the simultaneous surface attraction of the soil,
lead to an extremely rapid and complete destruction of
organic material. — As to the individual phases of the
decomposition of the soil, and as to the various influences
which act on it, we must await the results of continued
investigation with pure cultivations of bacteria from the
soil under various conditions.

We also possess some observations, although on the Transport of
whole unsatisfactory ones, as to the distribution and

696 DISTRIBUTION AND HABITAT OF TI1E BACTERIA.

transport of bacteria in the soil. The bacteria in the
first place generally reach the most superficial layers
with refuse fluids, from the air, &c. ; and hence in these
layers we find by far the greatest number of bacteria.
Many bacteria also pass at once from cesspools, &c.,
into somewhat deeper layers of the ground, 1 — 3 metres
under the surface, and impregnate these especially
strongly in the immediate neighbourhood of the cess-
pool. The question is whether bacteria can spread
from these points over considerable distances of the soil
in a horizontal and vertical direction. Currents of
water or air suggest themselves as the chief means of
transport. The former, when they soak through the
soil from the surface as far as the ground water,
ultimately carry the bacteria into the deeper layers and
into the ground water; or again, where there is great
evaporation from the surface, the water rising by capil-
lary action carries bacteria which have collected beneath
By downward into the upper layers. But on experimental investiga-
watet. tion neither mode of transport has proved to be prac-

ticable. Numerous filtration experiments on a large
and small scale have shown most distinctly that a layer
Of earth | to 1 metre in thickness is an excellent filter
for bacteria, and hence the purification of fluids from
bacteria must be still more complete in cultivated and
especially in clay soil, and where the fluid moves with
extreme slowness. In harmony with this we have the
fact, first ascertained by Koch and later on repeated
occasions in the author's laboratory, that the deeper
layers of soil contain very much fewer or indeed no
bacteria in contrast to the superficial layers which are
almost always rich in them (apart naturally from soil which
has been artificially disturbed). Further, it has been
repeatedly observed that wells which are well protected
against contamination with bacteria from the surface
and from the sides of the well furnish a water almost
entirely free from bacteria; that, further, wells of water
containing bacteria become the purer the more water is
pumped up, and the more ground water comes in from
the deeper layers of the soil. — Hence we can only assume

DISTRIBUTION AND HABITAT OF THE BACTERIA. 697

that bacteria penetrate to a very limited degree into the
deeper layers of the soil, more especially as it has been
shown from Hofmann's investigations that the passage
even of fluids and of substances in solution only takes
place with extreme slowness, and usually months and
years elapse before the layers in the neighbourhood of
the ground water are reached.

That a current of fluid passing upwards by capillary By upward
attraction can carry bacteria from the deeper layers of the c
soil to the more superficial has been recently asserted water.
by Soyka* as the result of a series of experiments.
Similar experiments, however, when repeated by
Pfeifferf and also in Koch's laboratory, have led to
entirely contrary results. However, even if such a
transport of bacteria by capillary currents were possible
to a slight degree, we could hardly regard this mode of
transport for bacteria as of any value under normal
conditions, for we have evidence that the deeper layers
of the soil are the poorest in bacteria, while the most
superficial layers have the largest numbers ; and, further,
with regard to man, the capillary current as a means of
transport for germs from the soil is scarcely of any im-
portance, because, as we shall see, it is only the com-
position of the actual surface of the ground which has
to be taken into consideration.

Whether currents of air passing through the soil can By currents of
carry bacteria along with them was first experimentally air>
tested by Niigeli, and then by Kenk, Soyka, Pfeiffer,
and others ; all these observers obtained the uniform
result that even strong currents of air were unable to
carry a single bacterial germ through a layer of earth
a few centimetres in thickness ; the layer of earth even
in the completely dry state acts perfectly as a filter,
and in ordinary soil, which is always slightly moist, and
in which the movement of the ground air is very slight,
there is so much less possibility of detachment and
transport of bacteria. — Lastly, we might also think that By continued
bacteria might spread by continued growth. The ^

* Prager med. Wochenschr., 1885, No. 28.

t Rrpert. d. anal. Ck., 1886, No. 1.— Zeitschrift f. Hygiene, vol. 1, Part 3.

(>98 DISTRIBUTION AND HABITAT OF THE BACTERIA.

energetic processes of oxidation in the soil show us that
active life, and in correspondence with that, marked
multiplication of bacteria, occurs in it ; but even were
the growth very active, the vegetation could only spread
extremely slowly over the enormously large surfaces
which a porous soil offers, and this mode of spread
would not come at all into consideration in the case of
pathogenic bacteria. — Finally, transport of bacteria can
occur in many instances by all sorts of animals which
live and move in the soil, for example, by worms, but
this can only take place to a very limited extent. On
the whole, then, we must regard the bacteria in the soil
as more or less fixed in a particular place, and only
altering their position slowly and over short distances.
Behaviour of The results of the recent investigations as to the

thepathogemc . . . 5* „

bacteria in the behaviour of pathogenic bacteria in the soil are thus of
great importance. We have to ascertain whether the
soil can in reality exert a specific influence on patho-
genic bacteria, whether such an influence is shown in
favouring the growth and the multiplication of the
pathogenic bacteria, or whether it affects their preserva-
tion and spore formation, or whether, in the third place,
it is only the spread of the infective agents from the soil
to man which depends on definite conditions of the
soil.

1 Do the From our present knowledge as to the conditions of

pathogenic ]{fe of the pathogenic bacteria, it seems very improba-
tipiy in the hie that they are able to multiply in the soil. The low
temperature in the deeper layers is of itself sufficient
to prevent entirely the multiplication of this class of
bacteria. In those upper layers, which always or at
times show a temperature of at least 16° C., growth of
pathogenic bacteria could occur if suitable nutritive sub-
stances were present, if there were nothing to hinder
the development, and if none of the more rapidly grow-
ing saprophytes were present. These conditions, how-
ever, are almost never fulfilled under ordinary circum-
Unfavourable stances. Numerous experiments by Bolton, Heraeus,
d5ionsiVhi the" anc^ others, have shown most distinctly that even the
typhoid bacilli, which are the least fastidious of all

DISTRIBUTION AND HABITAT OF THE BACTERIA. 699

the pathogenic organisms, absolutely require a small
quantity of the best nutritive materials for their growth
and multiplication. In this respect the pathogenic bacteria
show a marked contrast to some of the saprophytic
forms, which can maintain life with nutritive materials
of almost any quality, and can, therefore, grow actively
in the soil. Better nutritive materials may, however,
be occasionally found in certain localities in the most
superficial layers of the soil, but at the most only tem-
porarily, because rapid destruction and decomposition
is always being brought about by saprophytic bacteria,
and by the surface action of the elements of the soil.
Various pathogenic bacteria can, it is true, be cultivated
in pure diluted urine, and Schrakamp has also observed
a development of anthrax bacilli in soil which was pre-
viously sterilised, and to which urine, blood serum,
nutritive jelly, &c., were added. From this, however,
we cannot draw any conclusions as to the conditions of
the normal soil. The excreta, &c., reach it usually Direct exp
in a markedly altered condition, and containing nume- ^gatlvl^''
rous saprophytic bacteria. As a rule they become very results.
much diluted in the soil by rain, and the layers in
which they are in the first place retained are likewise
full of saprophytes and fermentative agents, and in a
suitable state for rapid decomposition of the material.
Hence manured soil presents very different nutritive
conditions to those of pure fluids, and conclusions as to
the behaviour of the natural soil can only be drawn from
experiments with real manured field and garden earth.
Experiments of this kind have already been made by
Koch. He attempted to grow anthrax bacilli in garden
earth, in very rich mould from the banks of rivers, in
the mud of the same rivers, and also in the mud of
streets, a little water being added to these substances.
Nevertheless no growth occurred. — Praussnitz has also
made investigations in this direction in the author's
laboratory, but has not as yet obtained any marked or
permanent multiplication of pathogenic bacteria in any
kind of soil, or by any mode of manuring. These ex-
periments are being continued, and it is very possible

700 DISTRIBUTION AND HABITAT OF THE BACTERIA.

that here and there degrees of uncleanness of the soil
may he found which permit a short-lived and local mul-
tiplication ; but on the whole such a property of the
soil is exceptional, even under the conditions employed
in laboratory work.. And these conditions are in so far
very much more favourable for the multiplication of the
pathogenic bacteria than are the natural ones, because
in them earth which has been previously sterilised at
100° C., and freed from other bacteria, and air not con-
taining carbonic acid, are always employed. In reality the
concurrence of the saprophytes which find their most
favourable conditions for existence in the soil, and also
the accumulation of carbonic acid, are in a very marked
degree unfavourable for multiplication of the pathogenic
bacteria.

Multiplication Hence it appears to be of relatively little importance
veryexcep- ^or *he question of the multiplication of pathogenic
tionally even bacteria in the soil, whether the latter is more or less
soil. contaminated, that is to say, impregnated with excreta.

Possibly greater or less contamination may lead to a
certain fluctuation in the prevalent species of bacteria,
but all of these belong to the category of the obligatory
saprophytes, and leave no room for the facultative
parasites which are much more particular as to the con-
ditions of their life. Without doubt it will at times
happen that a pure cultivation of pathogenic bacteria
(for example blood from animals suffering from anthrax)
reaches the upper layers of the soil along with good
nutritive material, and then multiplication of the
anthrax bacilli will occur in the soil so impregnated.
But this is evidently no special action of the soil, for
the same thing might happen on any other substratum.
In a similar manner typhoid and cholera bacilli, which
pass along with the fresh dejecta into a soil contain-
ing bad nutritive materials and numbers of saprophytes,
may multiply to a certain extent for a short time at the
expense of the nutritive materials contained in the
dejecta, in the same manner as would happen under
other very different conditions without contact with the
soil. Here there is no sort of favouring and specific

DISTRIBUTION AND HABITAT OF THE BACTERIA. 701

influence of the soil, and of the impurities of the soil,
but on the contrary rather an unfavourable action.

If, however, we ask whether the soil favours the pre- 2. Are patho-
servationof pathogenic bacteria, our answer must perhaps preserved in1*
be somewhat different. This might occur if circum- the soil ?
stances were present which favoured spore formation
or long preservation of preformed spores, or of those
formed in the soil, or retention of vitality by non-spore-
bearing bacteria. Soyka* has recently observed, in a
series of experiments with anthrax bacilli, that spores '
are formed more quickly when the fluid containing them
is mixed with soil than when they are kept in the
original fluid under conditions otherwise similar (at the
same temperature, &c.). Now spore formation in the No important
case of anthrax bacilli occurs chiefly at the surface of the spore Ce
fluids, and hence spores are the more numerous, and formation,
the earlier formed in a fluid the thinner the layer in
which it is spread out. In soil which is not saturated
with moisture, any fluids poured on it are quickly dis-
tributed in very thin layers, and thus offer the best
conditions for spore formation. But these conditions
are also furnished on any substratum when the fluids
are spread out in thin layers on the surface.

According to Soyka, acceleration of the spore forma-
tion is most marked when the soil contains such an
amount of moisture that from 25 to 75 per cent, of the
pores are filled with fluid. This gives a very large
margin, which besides was never sharply defined in his
series of experiments, for numerous spores wrere found,
and the delay in their formation was only trivial when a
hundred per cent, of the pores were filled, while where
the proportion was under 25 per cent, the spores were
so widely distributed that comparison was impossible.

Soyka was unable to observe spore formation in the
anthrax bacilli when the temperature of the soil was
below 18° C., or under conditions which would hinder
spore formation in fluids.

From these results it is evident that the soil exercises
no marked or specific influence on the formation of

* Fortschrilte d. med., 1886, Nr. 9.

702 DISTRIBUTION AND HABITAT OF THE BACTERIA.

On the other
hand spores
once formed
are well
preserved.

Preservation
of non-spore-
bearing
bacteria.

spores in the case of anthrax bacilli ; on the contrary, the
bacilli form spores in the superficial and somewhat dry
layers of the soil in the same manner — perhaps here and
there somewhat quicker, but certainly not to any marked
degree— -as in portions of the bodies of animals which
have died of anthrax and which are lying on the surface,
in the dejecta of anthracic animals, on nutrient vegetable
materials, in marshy flats, &c.

It is conceivable that in the case of some other patho-
genic bacilli, which are less disposed to the formation of
spores than the anthrax bacilli, spore formation may
occur in a more exclusive manner and much more
favourably under the conditions peculiar to the soil ; as
yet, however, we have no evidence in favour of such a
view.

On the other hand, pre-existing spores, or those formed
in the soil, are perhaps better preserved there than in
any other superficial substrata. In the latter, as the
result of rains, or of currents of water and air, which
may bring new nutrient materials, may again moisten
the dried masses, or may carry the spores to other
parts rich in nutriment, the spores may very readily
sprout and form bacilli, which then succumb to the
saprophytes present. In the soil, on the other hand,
the unfavourable nutrient conditions, and the unfavour-
able conditions of temperature, can almost always pre-
vent the sprouting of the spores, and thus we have an
explanation of the fact that existing spores can remain
there for a long time, and that we so often find in the
soil large numbers of resisting spores.

But even without previous spore formation the soil
may possibly preserve various kinds of bacteria, including
pathogenic ones. We saw previously that the chief reason
why non-spore-bearing bacteria so readily died under
natural conditions, was either because they were present
in fluid media, and were then exposed to the danger of
being overgrown by other bacteria, or because the loss of
water and the drying of the nutrient substratum led to
their death.

We can readily conceive that such complete drying of

DISTRIBUTION AND HABITAT OF THE BACTERIA. 703

bacteria as to lead to their destruction does not readily
occur in the soil, not even in the so-called dry soil,
because the air in it is saturated with moisture, and a
layer of vapour surrounds the elements of the soil ; but
that, on the contrary, as Soyka has suggested, the
arrangement of the fluid in the soil in thin capillary
layers surrounding the particles produces a sort of fixation
of the bacteria, and hinders such free circulation of the
organisms as occurs in thicker layers of fluid, and thus
both their overgrowth by other bacteria and their destruc-
tion by drying are avoided; and these two factors, which
are present in the soil in a very exceptional manner, lead
to preservation of non-spore-bearing pathogenic bacteria
to an extent which occurs much more rarely in other
substrata.

The result that the soil may possibly be a particularly good Explanation
preserving medium for bacteria, but does not permit their of the marked
multiplication, seems opposed to the experience mentioned the^oih1 ^ °
above that a soil impregnated with putrid fluids sets up
infective diseases in animals much more readily than the
putrid fluids themselves. But this fact is easily explained
without assuming a multiplication of these bacteria. In
putrid fluids parasitic bacteria are present in very much
smaller numbers than the saprophytic forms, among which
some are always present which furnish very poisonous
ptomaines. On account of these ptomaines we cannot
employ large doses of the putrid fluid if we wish to obtain
an infection ; after the injection of large quantities the
animals only die of intoxication, and when on the other hand
small doses are injected the chances of an infection are very
slight on account of the relatively small number of the patho-
genic bacteria. — If now the putrid fluids reach a porous soil
the individual bacteria are fixed and preserved, while there is
rapid destruction of the ptomaines. Numerous experiments
formerly performed, and also those carried on of late by Falk
and Soyka, have shown that the soil by its capillary attraction
splits up poisonous organic bases, and also ptomaines, in a
very short time. Hence we can introduce subcutaneously
into animals large quantities of an impure soil without in any
case causing intoxication, and hence with such a soil infective
diseases are much more easily produced than with the fluids
themselves. Very small quantities of the soil are usually
without any effect.

The question now arises whether this supposed, but

704 DISTRIBUTION AND HABITAT OF THE BACTERIA.

Local and as yet by no means proved, power of the soil of preserv-

seasonal

differences in nig pathogenic bacteria is subject to local and seasonal

Seso3to°£ variations; and whether these variations might suffice

bacteria *° exP^n tne ^oca^ an^ seasonal differences in the dis-

tribution of epidemic diseases as understood by Petten-

kofer ?

Although we have as yet no experimental proof of
such a view, it is probable that certain local and seasonal
differences in the preserving power of the soil do in fact
exist. Thus compact rock, which does not permit the
entrance of fluids and bacteria, would be out of the
question as a means of preservation. Further, the va-
rious forms of porous soil would show quantitative
differences according to the size of the particles and the
degree of porosity. Possibly also the greater or less con-
tamination of the soil is of influence, but only in so far
that if the soil contains a large quantity of saprophytes
and of nutritive materials, it will be less suitable for the
preservation of pathogenic bacteria.

As regards time also, certain variations may occur ;
more especially it is conceivable that a very moist soil
presents more the conditions of a fluid, and prevents the
rapid distribution and fixation of the bacterial masses
which are necessary for their preservation, while the
action of the air which, is present in the pores of a soil
only partially moistened does not occur, and thus preser-
vation is prevented. As excessive moistening of the
upper layers of the soil is generally accompanied by a
high level of the ground water, the sinking of the ground
water may frequently indicate increased suitability of the
soil for the preservation of pathogenic bacteria.
The preserva- But in spite of the possible existence of these local
all(l seasonal variations, the preserving power of the soil

n
the soil is, would not be in the slightest degree sufficient to exert

however, not . , , „ .-..,.

necessary for an exclusive influence on the spread of epidemic dis-
eases. For we cannot assume with regard to any species
of bacterium that the condition of preservation in which
it is present in the soil is at all necessary to fit it for
being transmitted to other individuals ; on the contrary,
all infective agents are without doubt capable of causing

DISTRIBUTION AND HABITAT OF THE BACTERIA. 705

further infection without and hefore coming in contact
with the soil. And further, the preservation of the
pathogenic bacteria is certainly not an exclusive property
of soil ; on the contrary, sufficient preservation can occur
in very various substrata, especially when the bacteria in
question can readily form spores, as in the case of the
anthrax bacilli, or are already spore-bearing when they
leave the body, as in the case of the typhoid bacilli.
Many kinds of soil may perhaps in this respect be of
more than average value, and the preservation of the
spores in them may be remarkably long and complete.
But there are always so many other possible modes of
distribution of the pathogenic bacteria that the action or
want of action of the soil in their preservation cannot in
very many cases exercise any marked influence on the
spread of the epidemic.

A third question arises, in what way bacteria preserved 3. How do the
in the soil can spread to man, and whether a definite bacteria d

condition of the soil, varying according to time and place,
Ms much influence on this spread ? The following man ?
modes of transport may come into play in the case of the
bacteria of the soil : —

1. Winds, which carry up the dust, and with it the winds.
bacteria, from the most superficial layers of the soil, and
transport them through the air. From what has been

said above as to the organisms of the air and as to the
movement of bacteria within the soil, it is evident that
such a detachment of bacteria is only possible in com-
pletely dry soil, and only from the superficial layers,
which are converted into dust. A thoroughly moist soil
does not permit the detachment of bacteria, nor does a
soil which possesses a superficial dry layer, but the outer-
most surface of which is moistened from time to time by
slight rains.

2. The ground water, and the water taken from it for Ground water.
drinking and other purposes. Where there is a thick

layer of cultivated soil above the ground water this mode
of transport cannot come into play ; but where the ground
water is only separated by thin layers of loose soil from
the surface, and where it can ultimately reach the sur-

45

706 DISTRIBUTION AND HABITAT OF THE BACTERIA.

Food.

By animal?.

Digging.

Seasonal
influences on
their spread
due to the
moisture of
the ground.

Behaviour of
the water in
the soil.

face if it increases in amount, and also when fissures
and cracks open a communication between the contents
of cesspools and the ground water used in houses, it will
occasionally happen that the bacteria poured into the
soil again return to man and to dwellings.

3. Articles of food which grow in the soil (potatoes,
turnips, roots, &c.) carry particles of earth adhering to
them, and large numbers of bacteria from the upper
layers of the soil, into dwellings, kitchens, kitchen uten-
sils, towels, &c., and thus ultimately to other kinds of
food.

4. Men and animals who come in any way in contact
with the soil, implements which are employed in culti-
vation, &c., can in a similar manner aid in the transport
of the bacteria from the soil to the domestic economy.

5. By digging the soil and laying bare the deeper
layers which may contain bacteria, while at the same
time dry winds prevail, numbers of pathogenic bacteria
may be detached which have reached the soil from de-
fective cesspools, or at a former time from the surface,
but which have been withdrawn from contact with the
outer air by being covered with new layers of soil. It
is possible that we may in this way explain the fre-
quently suggested connection between typhoid epide-
mics and digging up the soil of streets.

As a matter of fact it is evident that these various
modes of transport of the pathogenic bacteria of the soil
do not come equally into action in every soil and at every
season, but that local and seasonal causes of variation
exist, and favour or hinder one or other mode of trans-
port.

The seasonal influences are most distinctly seen in
the first and most widespread mode of transport, viz.,
the spread through the air ; and this is due to the
varying degrees of moisture of the upper layers of the
soil.

As to the important conditions of the moisture of the soil
in relation to this point we have obtained clearer information
by Hofmann's investigations.* In porous soil we have to

Arckiv f. Hygiene, vols. i. and ii., Part 2.

DISTRIBUTION AND HABITAT OF THE BACTERIA. 707

distinguish, in the first place, a superficial zone of evaporation
in which the degree of moisture of the soil is very variable,
and oscillates between complete saturation and marked dry-
ness ; in this zone, when of great breadth as the result of the
summer heat, the whole of the rain in late summer and
harvest often finds a place, and the filling of the capillary
pores does not reach to its lower border ; in this case there is
therefore always a dry layer between the most external part
which is temporarily wetted by the rains, and the deeper
layers of the soil in which the water lies. And under these
conditions all the impurities which reach the soil remain in
the upper dry zone.

Under this layer lies a zone which never dries, but in
which the capillary pores are always full of water. If this
zone receives water from above (when the upper dry layer
has been completely filled with rain water) the amount of
water in it remains the same, for the excess runs downwards
into the third zone, that of the ground water.

It is evident that, when a drying zone exists, the con- Favouring
ditions are the most favourable for the detachment and a^g^one.
carrying away of the bacteria of the soil by currents of
air. It is only in that case that this most important
mode of transport comes into play. During the whole
of the winter and a great part of the spring there is
usually no dry zone in our climate, and hence no possi-
bility for such a passage of germs into the air. In the
latter end of summer and in autumn, on the other hand,
this possibility is present, and is only absent from time
to time when the occurrence of rain renders the outer
surface moist.

As the existence of a dry zone always results in the The variations
cessation of addition to the ground water from above, and ™^ San^

thus leads to sinking of the level of the ground water, index of

, . . , .... the moisture

we have in the variations in the level of the ground water of the soil,

a fairly useful index of the possibility of a transport of
the bacteria of the soil by the wind. This index is not,
however, quite correct, because the temporary moisture of
the surface of the soil (sometimes lasting even for weeks
and months) and the cessation in the transport thus
occasioned find no expression in the variations of the
level of the ground water.

The existence of a dry zone has a further favourable

708 DISTRIBUTION AND HABITAT OF THE BACTERIA.

Further action effect on the number and variety of the bacteria trans-
zone. ryU1' ported by the wind, because all impure fluids, dejecta,
&c., and with them all bacteria, remain in the most
superficial dry zones. In this way the accumulation of
the most various kinds of saprophytes, and also of patho-
genic bacteria, takes place to a much greater extent than
in the case of a thoroughly moist soil where there is no
drying zone, because the continuous stream of water in
the latter case carries the bacteria to a certain though
moderate depth and removes them from the action of
the wind.

The other modes of transport are only to a slight
degree subject to influences varying according to season.
Formerly a variation in infective power was ascribed to
the ground water according as its level was high or low,
usually, however, the number of bacteria present in it is
but little influenced by alterations of the level.

The spread by food, man, and various materials can
perhaps be favoured by the presence of a drying zone, in
that when such a zone exists a large accumulation of bac-
teria occurs in the most superficial layers of the soil from
which the transport takes place ; nevertheless a constant
difference of this kind can only be made out in the case
of those soils which are exposed to continual contamina-
tion, as in the soil of streets, courts, &c. ; while the soil
of fields, for example, which are only impregnated at
considerable intervals with fluid containing bacteria, can
only show seasonal variations in the action of the mode
of transport as the result of a conjunction of accidents.

On the whole, therefore, it is practically only the drying
of the surface of the soil which increases the danger of
distribution of pathogenic germs from the soil.

influence of The existence of any influence on the transport of the
constitution bacteria of the soil as the result of the character of the soil
of the soil on in any given locality is not so evident. Here again it is
the bacteria . only a porous soil, and one which can take up large numbers
of bacteria, which could exert an influence on their dis-
tribution. Further, we may suppose that where the pores
are large the bacteria do not on the whole accumulate in
such numbers, but are more readily distributed over con-

DISTRIBUTION AND HABITAT OF THE BACTERIA. 709

siderable distances than in finely porous soil ; and this
must be the result, more especially when copious rains
thoroughly soak the soil, and when there is no drying zone.
In such a grossly porous soil the drying zone assumes
a special importance ; for it is only while it exists that
there is any chance of the bacteria being transported by
winds, or by men or things. Finely porous soil, on the
other hand, keeps back the bacteria in the superficial
layer to a much greater extent, and even possibly when
the dry zone is absent ; in this case the bacteria may be
distributed, not indeed by winds, but in other ways, for
example, by contact with man, &c., even when the sur-
face is moist, and hence the difference between the dry
and the moist stage is not so sharply marked in finely
porous soil.

We must, however, for the present leave it to experi-
mental investigations made with bacteria to confirm or
to correct these ideas, and to give us definite information
as to the special disposition of the individual kinds of
soil for the spread of infective germs.

From what has gone before we can at all events come Resume.
to the definite conclusion that the soil does not lead
to any special ripening, or even to active multiplication
of the pathogenic bacteria, but on the other hand, that
it possibly aids in their preservation, and in the distri-
bution of the bacteria so preserved. Both preservation
and distribution are probably subject to local and seasonal
variations ; for it is only a porous soil, and only at a time
when a superficial dry zone exists, and where the ground
water is as a rule sinking, that a preservation and more
especially a distribution of the infective germs can take
place.

By this property of preserving the pathogenic agents influence ot'
in an unaltered condition, and allowing their return oAfeeoU on8
again under certain conditions in large numbers to the
surroundings of man, the soil probably takes part in the disease
spread of many infective diseases ; and the dependence
of these properties of the soil on local and seasonal in-
fluences will ultimately find its expression in the local
and seasonal variations of many epidemics. The most

710 DISTRIBUTION AND HABITAT OF THE BACTERIA.

Frequent dis- important mode of spread, more especially of such patho-
the typhoid genie bacteria as reach the soil directly or in a round-
thesoilfr°m a^out waJ along with the dejecta of the sick (e.g.,
typhoid bacilli), and which either contain resistant spore
forms in the dejecta as passed, or form these in the soil,
is that in one or other of the ways mentioned they are
again carried into the household from the uppermost
layers of the soil. And this distribution only occurs
from a porous soil, and at a time when a dry zone exists
(in other words when the level of the ground water is
low), that is to say, it depends markedly on local and
seasonal predisposition.

Their distri- But even *ne typhoid bacilli are not always restricted
Imtion, to this mode of spread. We must assume that they

however, does *

not occur only can cause infection in other ways, and this assumption

the'soS.?8 is still more necessary in the case of those pathogenic

bacteria which do not reach the soil to the same extent,

or which (like the cholera bacilli) cannot be distributed

from the soil in the most common manner, viz., by

currents of air, for the reason that they cannot with-

. stand the necessary degree of drying. In the case of

the majority of the facultative parasites, therefore, their

preservation in and distribution from the soil forms in

reality a rare exception.

The patho- The important difference between our views and those

donnotafcequire of Pettenkofer is, therefore, that we (basing our opinions
infective on our present knowledge of the biology of the patho -
the result of genie bacteria and their behaviour in the soil) can find
6 soil!06 nothing in the soil which must of necessity act on the
pathogenic bacteria in order to make them capable of
producing infection. The idea formerly held as to a
sort of ripening of the infective agents under the
influence of certain mysterious properties of the
soil cannot be brought into accord with the recently
ascertained facts as to the biological properties of the
bacteria, and must now be definitely abandoned. Nor
can we assume that the multiplication of pathogenic
bacteria takes place exclusively in the soil (perhaps with
the exception of the as yet completely unknown cause of
malaria) , because other superficial substrata are as a whole

DISTRIBUTION AND HABITAT OF THE BACTERIA. 711

much more suitable for such a multiplication ; what the
soil really effects in a marked manner, viz., the preserva-
tion and the distribution of the preserved pathogenic
agents, is, however, not an exclusive privilege of the soil ;
on the contrary, the distribution of these infective agents
can also take place by other means and in other ways,
which are for the most part more available than the
roundabout way through the soil.

Further, the occurrence of local and seasonal varia- The local and
tions in the distribution of the infective diseases, which, predisposition

according to Pettenkofer, are only explicable on the as- is nj>
sumption that the soil exerts an influence, does not by means of the
any means necessitate the idea of a constant connection Bother waSys
between soil and epidemics. We see, on the contrary,
that the other modes of spread in which the soil does
not come into question, e.g., the spread by the food, by
contact, &c., are subject to local and seasonal variations
which are quite sufficient to explain the corresponding
oscillations of the epidemics (see the following part).

Bacteria are almost- always present in very varying Occurrence of
numbers in water. The varieties observed are almost ^ctteerna m
without exception saprophytes. Among these there are
some which are of special interest, because they are able
to multiply markedly in the presence of imponderable
quantities of the most simple nutritive materials, and at
a temperature of 8° to 10° C., and hence they are present
in large numbers in the most various kinds of water.
These "water bacteria" of which Bolton* has isolated six Bacteria
varieties, which are very widely distributed, influence the ^Stiply in
total number of bacteria in any particular water ; for water-
where they are present they multiply with such extreme
rapidity, that very soon the number of all the other
bacteria becomes insignificant compared with them. The
quality of the water is quite indifferent for these typical
inhabitants of the water; they multiply quite as markedly

* Bolton, Ztiitschr. f. Hygiene, vol. i., Part 1. — See Cramer, Die Was-
servtrsorgung von Zurich. Zurich, 1885. — Wolffhiigel, Arb. a. d. Kais.
Ges. Amt., 1885, vol. i.— Wolffhiigel and Eiedel, ibid., 1886, vol. 2.—
ieone, Atti cklla R. Acad. del Lincei, Sar. 4, vol. i.

712 DISTRIBUTION AND HABITAT OF THE BACTERIA.

Behaviour of
pathogenic
bacteria in
water.

in distilled water which is as pure as possible, as in the
so-called bad well water which is contaminated with
sewage. — Besides these special bacteria we have as
inhabitants of the water those forms which are cha-
racterised by their more advanced morphological de-
velopment, and by the variability of their vegetative
forms insisted upon by Zopf, viz., crenothrix, cladothrix,
beggiatoa. We require more accurate investigations as
to the character of the water which is necessary for the
development of these fungi.

Many of the other saprophytic forms apparently either
do not multiply at all in water, or only to a very limited
extent. Nor can any of the pathogenic bacteria multiply
in water even where the temperature is favourable,
because they absolutely require a certain even though a
small quantity of the best nutritive materials. Typhoid
bacilli require, according to Bolton's experiments, at
least 67 milligrammes of organic nutritive materials per
litre of water, cholera bacilli require 400 milligrammes
per litre. Such an amount of organic materials only
occurs extremely rarely in water which is employed for
household and drinking purposes ; and besides, in the
case of the pathogenic bacteria very much depends on
the quality of the nutritive materials, and even the
presence of a considerable quantity of the less nutritious
organic materials which are usually present in water is
unable to replace the necessary but small amount of
peptone and albumen.

On the other hand, the pathogenic bacteria retain their
vitality for a comparatively long time in water. Non-
spore-bearing anthrax bacilli and micrococcus tetragenus
live for about six days, typhoid bacilli free from spores
for fourteen to twenty days, spore-bearing bacilli from
thirty to ninety days or longer. In the case of cholera
bacilli Wolff hiigel and Riedel have made out a duration
of vitality of about eighty days, and frequently also a
multiplication ; however, in some of their experiments,
the results of which are not completely in unison, they
have probably sown too many organisms, and have
carried over a small amount of nutritive material from

DISTRIBUTION AND HABITAT OF THE BACTERIA. 713

the cultivation, which has heen able to exert a decided
influence on their multiplication and preservation. In
numerous experiments which have been made in the
author's laboratory multiplication of cholera bacilli has
never been observed in any water when only small
numbers of the organisms were sown ; on the contrary,
they have always died within eight to fourteen days.

In these laboratory experiments the conditions are
particularly favourable for the development and preserva-
tion of the pathogenic bacteria, because sterilised water
has always been employed for the cultivation experi-
ments. Under ordinary circumstances the saprophytes,
which are always present in large numbers in water,
must render the conditions much more unfavourable
for the existence of the pathogenic bacteria. This has
in fact been directly proved by experiments made by
Wolffhiigel and Kiedel, who have found that cholera
bacilli disappear in unsterilised water even after two
days, although large quantities are introduced.

The entrance of the bacteria into the water does not Mode of
occur to any great extent through layers of intact soil, bacteria6 into
or through the ground water. The unanimous results wells-
of the experiments made by Koth,* Bolton,t Heraeus,J
and others show that in the majority of wells the number
of bacteria constantly decreases the more fresh ground
water is drawn into them by continuous pumping.
Further, after the pumping has been continued for some
time there are unusually few bacteria in the wells if they
are well covered on the surface and protected, as far as
possible, from fresh contamination from the well wall and
from the pumping tube; e.g., where we have tubular iron
wells and conducting pipes. Hence we must conclude
that the bacteria reach the drinking and household
water chiefly by currents from the surface, and also by
cracks and passages which run through the soil from
cesspools, &c., towards the wall of the well. It is
evident that pathogenic bacteria can also reach wells in

* Viertelj.f. ger. med., N. F., Bd. 43, Heft 2.
t Zeitschriftf. Hygiene, Bd. 1, Heft 1.
J Ibid., Heft 2.

714 DISTRIBUTION AND HABITAT OF THE BACTERIA.

the same manner. Hence we have the best opportunity
for the infection of drinking water where an imperfectly
covered well stands in the middle of the ordinary dirty
court; as a rule all dejecta and waste water are poured
out on the soil of these courts, and further, the arrange-
ments are frequently such that the superfluous water
employed for washing clothes, for example, flows hack
again into the well. — At times, also, the ground water
which supplies the well contains numerous bacteria ;
this is the case, for example, when the distance from the
surface is slight, or when cesspools in the neighbour-
hoods of the wells reach as deep as the ground water, or
when the soil is exceptionally porous.

Factors which The number of bacteria in a water chiefly depends on
number of ^ whether varieties are present which are able to multiply
bacteria in jn ^e water, and whether the conditions are favourable

water.

for their multiplication. These conditions are the more
favourable the higher the temperature and the longer the
water is stagnant and able to maintain the newly formed
bacteria. Hence we find the greatest numbers of
bacteria in stagnant water and during the summer
months, and the smallest numbers in wells which are
much used and during the cold season of the year.
The other conditions of the water, the amount of organic
material and salts present in it, are not of importance
for the multiplication of these special kinds of bacteria,
nor for the number of bacteria in any given water. It is
only when the true water bacteria are absent, and sapro-
phytes are present, which require a large quantity of
nutritive materials, that the differences in the chemical
constitution find an expression also in the number of
the bacteria. — We cannot, therefore, draw any con-
clusion from the number of living bacteria in a given
specimen of water as to its infective power, or even as to
the degree of contamination ; such conclusions can only
be come to when we ascertain at the same time whether
aquatic bacteria are present, and whether the conditions,
such as the season of the year or the frequency with
which the well is used, are favourable for their multi-
plication before the specimen was taken.

DISTRIBUTION AND HABITAT OF THE BACTERIA. 715

It is always very difficult to pick out the pathogenic Demonstra-

i • * n i ^ e turn of the

bacteria from among the large number of saprophytes, presence of
And in attempting to ascertain their presence we have
also to remember that they do not as a rule live long in
well water ; that as they never multiply in the water,
every withdrawal of water, and every addition of pure
ground water diminishes their numbers ; and it is only
in those cases where there is repeated contamination by
pathogenic bacteria that the chances of demonstrating
them by cultivation are at all favourable. — It is probably
owing to these difficulties that pathogenic bacteria have
never as yet been demonstrated with absolute certainty
in any water.

In addition to the ground water which is chiefly
employed for drinking and household purposes, the means of
water which flows on the surface of the ground often
serves as a means of transport of saprophytic, and at
times of pathogenic bacteria. In fact the water in
gutters, streams, and rivers is particularly dangerous,
because it not unfrequently serves the double purpose
of taking up and removing waste water of the most
various kinds, and at the same time of supplying water
for household purposes.

Further, stagnant and superficial collections of water, Banks of
the muddy banks of rivers, and fields which are at times
submerged, are probably of special importance for the
etiology of many infective diseases. These act not only bacteria.
as means of transport for all sorts of disease germs, but
they also in all probability facilitate the growth and
multiplication of the facultative parasites. It has been
shown that anthrax, typhoid, and cholera bacilli can
grow well on moist, dead portions of plants, such as
often occur in enormous quantities on the banks of
rivers, in regions which are flooded, &c. In these places
the bacteria mentioned find a favourable temperature, as
well as the necessary moisture and nourishment, during
a great part of the year, and if a saprophytic existence
of parasites is possible anywhere in the natural sur-
roundings of man, it must be here. Such a saprophytic
growth is most likely to occur in tropical climates ; it

716 DISTRIBUTION AND HABITAT OF THE BACTERIA.

was there that Koch succeeded in demonstrating the
presence of cholera bacilli in one of the Indian tanks, and
proving that a marked saprophytic multiplication of the
bacilli had occurred on the banks of the tank.

Eactena m We daily take into our bodies very large numbers of

articles Of , . . , . , . . mm • , n

food. living bacteria, not only with water, but also with our

food. To some articles of food — for example, beer,
cheese, &c. — numerous bacteria are intentionally added
in their preparation. In the case of other articles of
food, of which the edible portions are formed beneath
the surface of the soil, large numbers of bacteria adhere
to the particles of earth surrounding them. Others
again, such as fruits, are covered with numerous
bacteria from the air, which are either fixed on their
sticky surface, or are deposited there by the condensa-
tion of watery vapour. Further, it very frequently
happens that articles of food which were originally free
from bacteria, or which were sterilised in their prepara-
tion (milk, meat, various kinds of cooked food), are in-
fected either by contact or from the air, and according
to their nutrient conditions and the prevailing tem-
perature, smaller or larger colonies of bacteria develop
on them.

In all these cases the colonies may consist of com-
pletely harmless saprophytes ; or, on the other hand,
bacteria may be present which are able to set up fer-
mentation, and which are not altogether indifferent, for
if taken into the body in very large numbers they may
exert their energies in too marked a manner in the
human digestive tract; or, again, the bacteria may
belong to a class which usually grow as saprophytes,
but which produce very active ptomaines, some of which
may cause morbid changes in the intestinal mucous
membrane; or, finally, pathogenic bacteria may be at
times present in the food.

Development Those bacteria which develop on food kept in the
parasites on house seem to be especially worthy of attention. Under
food1680* these circumstances the temperature is often very

DISTRIBUTION AND HABITAT OF THE BACTERIA, 717

favourable for a multiplication of facultative parasites ;
further, the nutrient substrata could scarcely be better
even if they were prepared for the artificial cultivations
of the pathogenic bacteria ; again, many articles of food
are solid, and thus it is not so easy for the saprophytes
to overgrow these bacteria. Milk, broth, and meat are
excellent nutrient substrata for typhoid and cholera bacilli,
and we cannot but suppose that these and similar patho-
genic agents, when they once reach the food, the vessels,
or washing-cloths, &c., either through the air, or from
the earth, or by contact, very readily multiply to such a
marked extent that the greatest dangers may result from
the use of such food.

Not only the facultative parasites, which find here Obligatory
conditions particularly favourable for their development, Parasites-
but also the obligatory parasites can be carried to man
by the food, and especially those which (like the tubercle
bacilli) are infective for animals as well as for man, and
are at times introduced by the use of meat.

The dangers on the side of articles of food can be
almost completely avoided by the mode of preparation —
by sufficient boiling and roasting — and by avoiding the
use of food which has been kept for a considerable time
after being cooked. But as we know, in all nations and
in all classes of the people part of the food is eaten in a
raw state, or after it has been kept for a long time, and
thus it contains numerous bacteria. The proportion of Local differ-
the whole food which is employed in such a dangerous

condition is very variable, and differs according to the bacteria in

, „ , i mi ^ i .-, • the food.

customs and manners of each people. Thus while in
Southern lands there is the greatest carelessness as
regards the food, even the larger portion of it being
used in a raw or half decayed condition, in other
regions there is such great care in the selection, treat-
ment, and preparation of articles of food that the danger
of this mode of infection is reduced to a minimum.

Hence the number of bacteria in articles of food, and
the danger of infection resulting therefrom, is evidently
subject to marked local differences, and seasonal varia-
tions can also occur with equal frequency. Thus, in

718 DISTRIBUTION AND HABITAT OF THE BACTERIA.

Seasonal onr country the summer is naturally the time of the year
•es' during which those parasites which require a high tem-
perature can most readily establish themselves on articles
of food ; further, on account of the presence of raw decay-
ing fruits autumn is a particularly favourable time for
contamination with numerous and different kinds of
bacteria, and it so happens that, at the same time of the
year, the various articles of food are exposed to greater
danger of contamination by the bacteria preserved in
the soil, because the latter are at that time readily
distributed owing to the formation of dust .on the sur-
face of the ground. This dust formation is in our
climate almost exclusively limited to the end of summer
and to autumn, because it is only then that a superficial
dry zone is constantly and for a considerable time pre-
sent.— Hence we have various reasons for believing that
at a particular time of the year exceptionally large
numbers of bacteria are taken into the intestine with
the food, some of which perhaps produce ptomaines, and
thus possibly prepare the intestine for more severe
diseases, while others may penetrate as infective agents
into the predisposed intestinal tract.

From what has been said, it is evident that articles of
food probably form such a marked factor in the spread of
the infective diseases that we must in future attempt to
gain a more accurate knowledge of this mode of infec-
tion.

Bacteria in Numerous bacteria of all kinds are also frequently
present in the artificial surroundings of civilised man ;
thus the clothing is for the most part very rich in
living micro-organisms, which have reached it partly
from the surface of the body and the excreta, and partly
from without by the dust and rain. Washing clothing
is not uncommonly the means of transport of faculta-
tive and obligatory parasites ; such a role on the part
of clothes is well known in the case of those infective
diseases which are localised in the skin (e.g., small-pox),

DISTKIBUTION AND HABITAT OF THE BACTEBIA. 719

also in the case of cholera, where, owing to the fact that infection by
the linen becomes soaked with the nutrient substances °
contained in the dejecta, multiplication of the pathogenic
agents may occur on it, so long as drying does not take
place. Infective diseases of wounds, diphtheria, puer-
peral fever, tuberculosis, &c., are also without doubt
frequently carried by linen and dressings. Unfortu-
nately we do not as yet know, and must still ascertain
by exact researches, how far the usual methods of
cleansing linen destroys the infective agents, or how
long they may retain their vitality in linen which has
been \vashed and put away.

The dwelling offers many opportunities for the pre- Occurrence of
servation and distribution of bacteria, and especially of
facultative and obligatory parasites ; a multiplication
within the materials, which in a narrow sense belong to
the dwelling, does not seem to occur. The soil under the In the soil
floors forms, according to Emmerich's investigations, a UI
particularly favourable reservoir, and often contains
enormous numbers of saprophytic, and not uncommonly
also of pathogenic bacteria. These are present partly
in the original and for the most part very impure
material, and in part they reach it through the medium
of the water used for scouring, which carries with it
sputa, remains of dejecta, &c., and passes through
the numerous joints and seams of the floor into the
porous material beneath. In this way the bacteria of
pneumonia, spores of tubercle bacilli, &c., can readily
reach the soil. It is probably quite exceptionally that a
multiplication of bacteria occurs here, because as a rule
the material contains very little water. But it is pro-
bable that various forms of bacteria can be preserved in
the porous mass in a manner similar to that which
occurs in the natural soil. The bacteria can be ex-
tremely readily detached and distributed from this
reservoir by the mechanical disturbances to which the
floor of a dwelling- room is exposed ; the large masses of
dust which rise from the seams at every step can be
readily seen in a beam of sunlight. — Where the flooring
is close and covered with oil colours, more especially,

720 DISTRIBUTION AND HABITAT OF THE BACTERIA.

however, where it is waxed and polished, this reservoir
of bacteria with its danger of infection need not be taken
into consideration.

Further, the furniture, curtains, and corners of the
rooms, which are usually insufficiently cleaned, form
places on which bacteria may be deposited and preserved
for a considerable time.

Bacteria in The refuse of houses and of cattle stalls forms also a
favourable place for the accumulation of bacteria. The
intestinal excreta contain at times infective agents mixed
with the large numbers of saprophytes; for example,
typhoid bacilli, cholera bacilli, tubercle bacilli, anthrax
bacilli, the bacilli of swine fever, of chicken cholera, &c.;
further, probably the infective agents of dysentery and of
the epidemic diarrhoea of children. Fresh urine seldom
contains micro-organisms, but it is a suitable nutritive
substratum for the most various kinds of bacteria; we must
further bear in mind the kitchen refuse, kitchen water and
washing water, which are for the most part laden from
the first with numerous bacteria, and can also serve as a
settling place for others when it stands for a long time.
Not a good All these waste materials have up to the present been
nutritive sub- looked on as the chief nutritive materials for pathogenic

stratum for . . , /

pathogenic bacteria, and in this respect have as a rule been much
over-estimated ; on the contrary, they usually offer such
excellent nutrient conditions for the saprophytes that
they are totally unsuitable for the growth of infective
agents. We see in all waste waters, in putrid fluids,
&c., that the facultative parasites, even when they are
sown in them in enormous quantities, die in a few hours,
or at most days ; and it is only in the spore form that
they can be preserved (without multiplication) for a
longer time.

Dangerous on Hence these waste materials are only of importance
-account of the for the spread of the infective diseases in so far as they
dejecta which may at times contain obligatory or facultative parasites
^ which come from the bodies of diseased individuals ; and
hence the most important hygienic point with regard to
the removal of the waste materials is that the whole
mass, with the infective agents which may be present in

DISTRIBUTION AND HABITAT OF THE BACTERIA. 721

it, should be removed as quickly and completely as
possible from the dwellings and from the neighbourhood
of susceptible individuals. This aim will be best fulfilled Their prompt
by a system of drainage which is at the same time com-
bined with a constant and sufficient supply of pure water,
thus rendering the carrying out of cleanliness easier.
The system of removal of refuse by means of pails seems
less satisfactory, especially when by this means the
excrement and the infective agents in it are thrown on
gardens or fields in the neighbourhood of dwellings, thus
leading to the preservation of the germs, and therefore
probably to their re-introduction into the dwellings.
The system of cesspools, by storing up the masses for a
longer time, affords a better guarantee than the pail
system for the death of the infective bacteria before they
reach the ground. A decided disadvantage of the two Disadvan-
last-mentioned methods as compared with the drainage ^her °
system is, that there is always a danger of infective germs methods,
spreading in some way or other to the surroundings of
man, from dried masses in the exit-tube ; while in the
former system the water-closets and pipes leading there-
from can be readily kept in a clean and moist condition.
And further, stagnant gutters, dirty courts, &c., with
their multifarious dangers of infection, can only be effec-
tively dealt with by flushing with water and by drainage. —
The question as to the hygienic value of the methods of
cleansing towns must therefore be reconsidered from the
points of view shortly indicated above; we must also
trace out more accurately the fate of the pathogenic
agents in each of the systems employed, and of course
we must also carefully weigh other interests before
coming to a final conclusion as to the value of any given
system. At all events the most important hygienic Necessity for
points of view from which these matters have up to the
present been considered are incorrect, because the view
has been acted on that especially good nutrient materials
for pathogenic bacteria are present in the refuse materials,
and that it is necessary to keep the soil free from these
substances, and to remove them from human dwellings,
in order to prevent a development of disease germs in

46

722 DISTRIBUTION AND HABITAT OF THE BACTERIA.

them or in the contaminated soil. We must undoubtedly
give up this view, since we have become better acquainted
with the conditions of life of the pathogenic bacteria ;
and we cannot now see in a contamination of the soil
such a great and immediate danger of infection as for-
merly, especially when the water required for household
purposes is not taken from this soil, but is conducted
Significance from a distance by a system of pipes. Of course, how-

of contamina- . J . £ i Av

tionofthe ever, it is very desirable for other reasons to keep the
soil pure, and this is attained at the same time and in
the most complete manner by those methods which keep
prominently in view as rapid a removal of all pathogenic
agents as possible from the dwelling-house. The neces-
sity for and the sanitary effect of drainage thus remain
the same, and it is only the basis on which the precau-
tions are taken which is altered in accordance with the
more recent views.

infection as The profession and business of the individuals also in

profeTsionand manv wajs aid the spread or the reception of pathogenic

occupation, bacteria. In former times, for example, the infective

diseases of wounds were undoubtedly often carried by

physicians who did not at that time hesitate to examine

the infected wounds of one patient and the fresh wounds

of another with the same imperfectly cleansed finger.

infection by Even now infection is frequently carried by the clothes

and liands of tllose medical men who do not rightly
estimate the dangers of infection. In like manner mid-
wives, to whom is almost entirely to be ascribed the
transmission of puerperal fever, nurses, washerwomen,
old clothes men, rag-collectors, &c., very often lead to
Opportunities the further spread of infective agents.-' — We only require
to specially mention further the manifold possibilities of
infection to which children are wont to expose them-
selves ; how they cover their hands now with the soil of
dirty courts, now with the water of gutters, and the most
various objects rich in bacteria, and then the next mo-
ment place them in their mouths, or eat their food with
their dirty hands. It is difficult to understand how
when a child becomes ill from typhoid fever, diphtheria,
&c., the majority of doctors, in spite of these dangers of

DISTRIBUTION AND HABITAT OF THE BACTERIA. 723

infection which are constantly present and very evident,
always search for the ominous glass of "impure " water
which has in their opinion caused the disease.

Large numbers of bacteria are also present on the Bacteria on
surface of the human body. The most various forms of the 06

bacteria have already been demonstrated on the skin, in

the sweat from the feet and axilla, &c. It is evident On the skin.

from the researches of Forster,* that in spite of appa-

rently careful washing, bacteria still adhere to and

retain their vitality in the folds of the skin of the finger

and under the finger nails ; he found that, even after

cleaning the hands with brushes, water, and soap, if the

fingers were pushed into nutrient jelly a varying number

of bacterial colonies constantly developed.

On the internal surfaces of the body still greater in the mouth.
numbers of bacteria are found. For a long time sapro-
phytes have been known to exist in the mouth, which
excite fermentations, and bear a distinct relation to
caries of the teeth (p. 391) ; various forms of pathogenic
bacteria have also been observed there. Thus Kreibohm
in a relatively small number of cultivations from the
secretions of the mouth has isolated four different forms
which cause septicaemia in animals (see p. 319) ; and
also the bacillus crassus sputigenus, which occurs com-
paratively frequently in man, which likewise causes
septic infection in some animals, and which produces in
its cultivations a violent poison, killing those animals
which are not susceptible to infection by intoxication if
introduced in large doses. This state of matters is
readily intelligible when one considers that in the cavity
of the mouth there exists a very suitable temperature,
and in the dead epithelium, &c., a good nutritive mate-
rial for the development of pathogenic bacteria. Hence
it is readily conceivable that parasitic bacteria, which
require a special point for their invasion of the body, can
live for a time as epiphytes, till they find an opportunity
of entering the body, and thus the occurrence of an infec-

* Centralb. < Uin. med., 1835, Nr. 18.

724 DISTRIBUTION AND HABITAT OF THE BACTERIA.

ratory mucous
membrane.

In the
stomach.

tion need not be immediately preceded by the reception
of the infective agent. Possibly this is the meaning of
the observation made by Loeffler on the presence of the
diphtheritic bacilli in the secretions of the mouth of a
healthy child (see p. 287).

Ontherespi- Various bacteria (e.g., Micrococcus tetragenus) are
also found in the laryngeal mucus, and in that of the
trachea and bronchi ; these have been carried in by the
respired air, and have in part multiplied to a considerable
extent in the mucus.

Enormous numbers of bacteria are also met with in
the intestinal tract. Numerous forms are found even
in the contents of the stomach. It has been erroneously
assumed that the acid contents of the stomach kill most •
forms of bacteria ; this is, however, not the case.
Feeble action Experiments which have been made by Mac Fadyan
]?uice6 gastlic in the autllor's laboratory have shown that even the
strongly acid gastric juice of the dog can kill only
cholera and anthrax bacilli with anything like con-
stancy, that, however, most other bacteria are not so
susceptible to the action of the gastric juice, and can
pass in a living state through the stomach even when
conditions are as favourable as possible for an energetic
action of the gastric juice ; among bacteria which
behave in this way may be mentioned micrococcus
tetragenus, staphylococcus aureus, bacillus cuni-
culicida, &c.

Hence there is for the most part only a temporary
hindrance to development in the stomach, and vegeta-
tive forms such as spores reach the small intestine in a
living condition in large numbers. There they find a
good opportunity for development so long as the reaction
of the chyme remains neutral or faintly alkaline ; it is
true that this multiplication appears to be limited
chiefly to certain definite forms of bacteria, so that in
spite of the multiplicity of forms and varieties which
strikes one at first, there are some which evidently find
in the intestinal contents a particularly favourable soil
for multiplication, and occur there almost constantly.
These prevailing varieties seem to vary according to the

In the
intestine

Some prevail
ing varieties.

DISTRIBUTION AND HABITAT OF THE BACTERIA. 725

composition of the food as well as the course and stage of
digestion. — The occurrence of an acid reaction in the
intestinal contents must cause marked alteration in the
bacterial life in the intestine. More especially do organic
acids, such as occur in the later decompositions of the
chyme, exert a particularly marked inhibitory action on
many bacteria ; it is only some forms which are excep-
tionally insensitive, such as lactic acid and butyric acid
bacilli, which still remain capable of development, and
thus gain the mastery the sooner. — Anaerobes are also Anaerobes,
constantly found in the intestines, and often in such
large numbers that there can be no doubt that they
have multiplied there. This is easily intelligible, be-
cause in certain sections of the intestine, and in certain
layers of the intestinal contents, there is always a
deficiency of oxygen sufficient to permit the development
of anaerobes.

Among the large numbers of intestinal bacteria the Pathogenic
saprophytes are most numerous, nevertheless those h^es^ne
bacteria which do not grow so quickly as the sapro-
phytes, and are hence as a rule hardly adapted for
concurrent growth with them, not uncommonly multiply
to a marked extent, and possibly grow in the folds of
the intestinal wall which are more removed from the
action of the saprophytes of the chyme. In this way
bacteria may develop in the intestine which are
dangerous to the body, partly by means of their
ptomaines, and partly by penetrating into the intestinal
wall and causing infection.

We must await future investigations for a more
accurate knowledge of the intestinal bacteria, for an
isolation of the varieties which occur most frequently
or regularly, and also of those which only occur now and
then, and for facts as to their functions and their
effects.* — This study is to some extent rendered difficult
by the fact, that in microscopical preparations made

* While those sheets were passing* through the press, an extensive
research, which has just been published by T£tScherich(Die Darmba&terien
des Sauglings, Stuttgart, 1886), forms an important beginning to the
investigations in this department.

726 DISTRIBUTION AND HABITAT OF THE BACTERIA.

Some of the
intestinal
bacteria do
not grow in
the ordinary
cultures.

from the contents of some part or other of the
intestinal canal, or from the secretions of the mouth,
we see a much greater number of varieties of "bacteria
than when the bacteria contained in the same specimens
are isolated by our ordinary methods of cultivation.
It is evident that only a small fraction of the bacteria
which are present develop. It is by no means clear
what is the cause of this result of cultivation. Some of
the bacteria which do not, appear in the ordinary culti-
vations are evidently anaerobes, and a markedly better
development of bacteria is often obtained when the
material is cultivated in the absence of air. Others of the
bacteria which are seen and stained in the microscopical
preparations have probably been so affected by the action
of the gastric juice, or of the organic acids of the intes-
tinal contents, that they grow very slowly, and only in
specially favourable fluid nutritive media; hence Buclmer
was able to cultivate a greater number of varieties from
the intestinal contents by the employment of isolated
cultivation in fluid media, and by carrying on the culti-
vation for a longer time than when he limited himself
to jelly plates. It is also possible that the mucous
membrane may exert some inhibitory influence on the
bacteria, and that this may continue even after their
inoculation into cultures.
Absence of While the external and internal surfaces of the body

bacteria in the . , , TI-.TI • r* n

interior of the are thus richly supplied with bacteria we find none in
healthy body. tlie jnterior of the body under normal conditions (see
p. 83). It is only when parasitic organisms have
penetrated into the body, and have set up disease there,
that we have the presence of specific bacteria either in
Exceptions, the blood or in various organs. Further, Wyssoko-
witsch has shown that bacteria may be temporarily
present in an apparently quite normal body when
bacteria, either saprophytes or at any rate species not
infective for the animal in question, have penetrated
into the blood through a wound. Such bacteria are
deposited chiefly in the liver, spleen, and medulla of
bone, and remain there in a living condition for a
length of time varying from a few hours to days, while

DISTRIBUTION AND HABITAT OF THE BACTERIA. 727

spores, e.g. , those of bacillus subtilis, may live for
several months (compare p. 644).

The secretions of the body also, more especially the Absence of
urine, are according to the investigations of Wyssoko- of Cpl?ho

witsch * free from bacteria, even when infective bacteria on.es' in the
are present in the body and circulate in the blood. It
is only in the cases where there is plugging of the
vessels of the kidneys b}7 masses of bacteria, and in con-
sequence necrotic patches with marked lesion of the
tissue, that we have an excretion of bacteria in the urine.
Such a state of matters is almost always seen after the
injection of staph. aureus into the blood, but these
bacteria do not appear in the urine soon after the
injection even when large numbers were introduced, but
only after deposits have been formed in the kidney and
have opened up artificial passages.

Gunning f has examined the air expired by man for Absence of
bacteria. He found that when the air was expired
through a nutrient solution there was no infection of
the latter if only the entrance of saliva, &c., was pre-
vented. As a matter of fact we must, from what we
have learnt as to the detachment of bacteria from moist
surfaces (see p. 688), regard it as very improbable that
bacteria would be detached from the constantly moist
mucous membranes and carried with the current of
expired air which is constantly saturated with moisture.
— Hence the only way in which we can conceive that
organisms present on the mucous surface of the respira-
tory tract can spread through the air, is that in speaking
and coughing small particles of fluids are detached,
expelled, and remain mixed for short distances with the
expired current of air, or that sputa dry up after their
expulsion, and are converted into dust.

* Zeitschr.f. Hygiene, Bd. 1, Heft 1.

f Klin. Monatbl.f. Angenheilk,, Jahrg-. 20, 1882,

'•28

PART VII.

THE MODE OF SPREAD OF THE INFECTIVE DISEASES.

The principal IN the following paragraphs we shall sketch shortly
modeofspread the mode of spread of the human infective diseases, hut
tfvefdiseases on^y in so fai> as ^ bears an intimate relation to the
biological facts mentioned in the preceding pages, to the
distribution of the pathogenic bacteria, and to the con-
clusions already drawn. And even within these limits
we shall by no means attempt to give a complete de-
scription in view of the large number of these diseases
which never completely coincide in their mode of spread,
of the number of the problems to be solved, of the
numerous isolated facts obtained by investigation and
observation, and of the manifold hypotheses and theories
which have been promulgated. This limitation will be
the more permissible, because in a former chapter on
" Cholera " a detailed description of the mode of spread
of at least one kind of infective agent has been given,
and to this we must refer the reader as an example
which may be extended on the fundamental lines to be
mentioned below.

In considering the mode of spread of the infective
diseases we have in the first place to take into con-
sideration the sources of infection, the modes of trans-
port to man, and the points of invasion at which the
penetration of the infective agents into the healthy body
occurs. Then we have to pay special attention to the
individual predisposition and immunity, for these points
influence the mode of spread of many infective diseases
in a high degree. Finally, we must shortly consider
the meaning and the causes of the local and seasonal
variations in the epidemic distribution of the infective
diseases.

MODE OF SPREAD OF INFECTIVE DISEASES. 729

1. The Sources of Infection.

At the present time we only reckon as infective All infective
diseases those affections which are caused by the caused by*6
penetration of a pathogenic agent from without into ^^ly^eh
the body of the patient, and its multiplication there, the body of the
Hence a relatively insignificant quantity of the virus is P'
always sufficient for the infection, but a certain time
usually elapses before the development of the action, this
time being necessary for the multiplication of the virus.

If a noxious agent must be employed in a certain
and large dose, if it does not multiply in the body
of the patient, and if the action sets in relatively
quickly, the process is comprehended under the term
" intoxication." And in like manner when disease is pro-
duced by a so-called miasma, that term implying a
gaseous chemical substance or a mixture of unorganised
substances not capable of reproduction in the body, we
regard it not as infection but as intoxication.

From the fact that reproduction is necessary, it follows Hence the
that the infective agents are all organised beings. It agent? areW
has been further ascertained by the researches of the ™& organisms.
last ten years that these organisms — quite apart from
the animal parasites — chiefly belong to the class of bac-
teria ; it is possible, however, that the exciting agents
of certain human infective diseases belong also to other
as yet imperfectly known classes of micro-organisms,
e.g., the mycetozoa.

It follows also, from the reproduction of the infective All infective
agents in the body of the patient, that all true infective

diseases can be transmitted continuously from sick to from the sick

i 1,1 .,..,, , ., , , to the healthy.

healthy individuals, although it is possible that for
reasons to be discussed later this transmission is at
times accomplished only under marked difficulties, and
at certain stages of the disease, and in one particular
way. Quite recently the malarial virus has been trans-
mitted to healthy individuals by inoculation of the blood
of sick people, and hence the infective character of this
disease has been demonstrated with certainty.

Although this power of multiplication and trans-

730 MODE OF SPREAD OF INFECTIVE DISEASES.

mission is common to all infective agents, we have still
to ascertain their natural mode of spread in each in-
dividual case, and especially whether and to what extent
the infective agents are transmitted from the sick to the
healthy under the ordinary conditions met with in
practice.

With refer- The natural mode of transmission evidently depends
natural ^ode on whether the infective agents can leave the body of

°ue?tiondisthe tlie sick in a state caPa^e of producing infection. If
whether they are given off from some diseased surface of the
^producing6 body in sufficient quantity, in a living state and suf-
gtaooff-to™ ficien% resistant, then the disease may be transmitted
the sick. directly from the sick to the healthy, and spreads under

certain circumstances by contagion.

Contagious— If, on the other hand, the infective agents which are
ous'infec^fve reproduced in the body of the sick do not leave it at all,
diseases. or onjy in a g^g incapable of causing infection, the
infective disease in question is non-contagious. The
infective agents which cause these diseases must be
located somewhere in the surroundings of man, from
whence they can penetrate into healthy individuals, and
where they can also probably continue to multiply.
Hence all the non-contagious infective agents are
capable of a saprophytic existence, and belong to the
group of facultative parasites (see p. 629). The most
important representatives of this group are the infective
agents of malaria.

In the group of the contagious infective agents we
are at once struck by a remarkable variety in the
degree of contagiousness. This undoubtedly depends
in part on the unequal resisting power of the healthy
body against the various pathogenic agents, an influence
which will be dwelt on presently ; in part also, however,
on the quantity and the resisting power of the infective
agents which are given off from the diseased body.
Contagion by Some of these are very vulnerable and quickly die after
' they leave the body, and therefore can only pass from
the sick to the healthy by direct contact. Others
retain their vitality in the surroundings of the sick for
some time after they are given off from the body ; they

MODE OF SPREAD OF INFECTIVE DISEASES. 731

can therefore be transmitted not only by direct contact Contagion by
but also by all sorts of objects which play the r6le of objecS! 3
transporting agents ; some are characterised by a par-
ticularly lengthened resisting power, and in the case of
these, the number of modes of transport is markedly
greater. In effecting the transport, and in preserving
the infective agents, surrounding objects are not all of
equal value, some act better, others worse. Porous sub-
stances, soil, articles of clothing, &c., appear to be
particularly well fitted for these purposes.

In the preceding paragraph we have only referred to the
case where the objects in human surroundings act merely
as indifferent means of transport for the contagious
infective agents, and where the latter do not grow or
multiply on them ; these infective agents are only able
to multiply in the human body, and therefore belong
to the obligatory parasites.

But there are also contagious infective agents which
can lead a saprophytic existence on the dead materials
in our surroundings, and must therefore be classified as
facultative parasites. In this case there is a multipli- Multiplication
cation of the sources of infection outside the body of the £ive agents on

patient, and this may go on to such an extent in our sur-

roundings, that there are in fact more chances of infection

by the infective agents produced outside the body than

by direct or indirect transmission by indifferent objects

of the infective agents given off from the patient. On the

whole, however, the simple transport of resistant infective

agents by various objects is in many respects of as great

importance for the spread of a disease as when a cer-

tain degree of multiplication is possible outside the

body ; where the obligatory parasites are preserved for a

long time, and are very resisting, the important influence

of the surroundings is often as marked as when multipli-

cation of the possibly less resistant facultative parasites

has here and there taken place. In recent times special Slight import-

stress has been laid on the distinction between the infective phytic gSrawth

agents according as they belong to the facultative or to

the obligatory parasites, or according as they multiply

in the surroundings, or pass through them unchanged ;

782

MODE OF SPREAD OF INFECTIVE DISEASES.

1. Contagious
obligatory
parasites with
slight resist-
ing power.

With greater

resisting

power.

2. Contagious

facultative

parasites.

Spread of
anthrax.

but this distinction is not of great importance from the
point of view of the mode of spread of human infective
diseases.

To mention some examples, we have in the group
of the contagious obligatory parasites infective agents
which are distinguished by slight resisting power and
require direct inoculation ; for example, the agents of
syphilis, gonorrhoea, and hydrophobia. To those dis-
eases which can also be carried by various objects on
account of the greater resisting power of their causal
agents belong small-pox, measles, scarlatina, tuberculosis,
glanders, diphtheria, and the majority of the infective
diseases of wounds. Differences in the contagiousness
of these diseases are either due to the degree of resisting
power of the infective agents, or to the fact that the
situation of the points of invasion and the special protec-
tive arrangements of the healthy body only permit their
entrance in rare cases.

To the group of the contagious facultative parasites
belong the exciting agents of typhoid fever, cholera, and
anthrax. Here also the chief mode of spread is by
means of surrounding objects, which only act as trans-
porting agents, viz., clothing, water, soil, &c. ; at times,
however, multiplication or fructification also occurs on
articles of food, in regions which are marshy, or where
vegetable remains are plentiful. &c. This occurrence
may exert a special influence on the mode of spread of
the disease, because the maintenance of the species is
thereby rendered certain for a considerable time, and
also because, as in the case of anthrax, the formation of
resisting spores occurs at times only outside the body.

Anthrax behaves very differently according as it pursnos
the course of a septicasmia as a result of a cutaneous inocula-
tion, or of an intestinal anthrax from swallowing food con-
taining spores. In the first case, bacilli are not usually given
off from the affected body ; the surface of the wound is
occupied by other bacteria, and it is only at times that
anthrax bacilli are excreted in the urine; after death the
cadaver may become a prey to putrefactive bacteria without
the passage of virulent anthrax bacilli into the surroundings.
In such cases — for example, in animals artificially inoculated

MODE OF SPREAD OF INFECTIVE DISEASES. 733

with anthrax — it is evident that healthy animals do not easily
become affected, even when they live in close contact with
the diseased ones. On the other hand, in intestinal anthrax
quantities of dejecta containing anthrax spores are poured
out on the meadows from which healthy animals obtain their
food, and thus it is easy to understand how the disease
spreads by the spores which are preserved in the grass. In
like manner in burying the bodies of animals which have
died of anthrax, and which have been opened, blood, &c., may
be left on the surface of the soil, and spores subsequently
form there and ultimately get into the fodder. — While, how-
ever, in this mode of spread the pathogenic agents are as a
rule ultimately killed or interfered with by some meteoro-
logical influence, it is probable that there are some natural
abodes of the anthrax bacilli where they multiply outside the
body and constantly form new spores, these abodes being
therefore dangerous and permanent reservoirs ; situations
of this kind are present in the neighbourhood of rivers and
marshes, where sufficient moisture, favourable temperature,
and a plentiful supply of dead vegetable substances are
present, and thus in exceptional cases a saprophytic growth
of anthrax bacilli can take place. From these situations the
spores may be transported to meadows by means of floods,
and there give rise for a series of years to outbreaks of
disease, although the multiplication of the infective agents
may be limited to the body of the diseased animal. — In the
case of man, as is well known, infection with anthrax occurs
almost exclusively by means of the bacilli and spores developed
in the diseased animal, and adhering to the skin, hairs, &c.,
and the fact that the formation of the spores occur for the
most part after the death of the animal does not in any way
detract from the contagious character of this mode of spread.

Various other infective agents may show a certain Parasites
amount of saprophytic growth, which, however, is of less Jj}]"5^ J^JJJ
importance as regards their spread than in the case of saprophytic
typhoid fever, cholera, and anthrax. The staphylococci gl
are very widely distributed ; but it is relatively unimpor-
tant whether their number increases only as the result of
constant reproduction in pus, or also as the result of
saprophytic growth. The streptococci, erysipelas cocci,
&c., are able to multiply on dead nutrient substrata
under favourable conditions ; but the usual mode of
spread to healthy individuals is nevertheless either in
the fresh state by contact, instruments, &c., or in the

734 MODE OF SPREAD OF INFECTIVE DISEASES.

preserved state by clothes, dressings, furniture, or from
the surface of the body.

Unequal re- Also among the so-called facultative parasites we find
of%h?facnTta- very varying degrees of resisting power, and this in-
tive parasites, fluences the mode of spread to a much greater degree
than the temporary saprophytic multiplication. Anthrax
spores show, for example, a very marked resisting power,
and hence can be carried by the most various objects, and
can act after a very long interval of time ; the spores of
the typhoid bacilli which are possibly present in large
numbers in the dejecta of the sick do not, it is true,
possess such great resisting power, but they can never-
theless retain their vitality for several months in various
substances, in fluids, and in the dry state ; the cholera
bacilli, on the other hand, as mentioned above (p. 444),
die in a few days under the conditions normally present
in our surroundings.

Non-con- In the third group of the non-contagious facultative

tafive 8 faCUl" parasites we must include the exciting agents of malaria,
parasites. which, however, are as yet completely unknown ; these
organisms possibly belong to the mycetozoa, and pro-
bably multiply in water which is rich in vegetable
materials, and especially on marshy ground, and are
carried when drying occurs into the air immediately
over the surface.

For a long time it has been the fashion to employ the

term non-contagious for all those infective diseases in

the spread of which our surroundings play a distinct role,

and in these cases — for example, in malaria — it has

been assumed that the infective agents are transmitted.

Pcttenkofer's not by the sick, but by the surroundings. This incor-

typho^fever rec* yiew as *° tne sources of infection has even been

and cholera applied to the obligatory parasites ; but it is the faculta-

last group. tive parasites, more especially such as the exciting agents

of typhoid fever and cholera, that have been designated

by a large number of epidemiologists as non-contagious,

and placed in the same category as malaria.

Undoubted Apart, however, from undoubted practical experience
nessof typhoid ^at cholera and typhoid fever are contagious, the view

fever and -just referred to, and which is now held chiefly by Petten-
cholera. J

MODE OF SPREAD OF INFECTIVE DISEASES. 735

kofer, is irreconcilable with the results of the more

recent experimental investigations with regard to the

specific exciting agents of typhoid fever and cholera.

We see that both in typhoid fever and cholera the living

infective agents of these diseases are given off in large

numbers in the dejecta of the sick, and there is abso-

lutely no reason why they should not transmit the

disease to a healthy predisposed individual, either by

immediate contact, or through the intervention of some

object. Pettenkofer assumes that these agents as they Excretion of

come from the sick are not ripe, and are not able to

cause infection ; and he holds that they must first ac- infection by
quire their infective properties in a suitable soil outside
the body. This idea of a specific transformation of the
infective agents in the soil could, however, only be held
so long as we were completely in the dark as to the nature
of the infective agents ; it is no longer admissible in the
present state of our knowledge as to the biology of the
infective agents of typhoid fever and cholera. And be-
sides, we have definitely ascertained from experiments on
animals, as well as from involuntary experiments on
man, that there is no necessity for a transformation of
the infective agents after they are given off by the sick
in order to enable them to cause infection.

The possibility of the spread of these diseases by Role of the
contagion, and its occasional occurrence, must there
fore be looked upon as undoubted facts. It is true that °f both
the surroundings play a very marked part in the natural
distribution of these diseases, but they do so chiefly by
preserving unaltered the infective agents given off by
the sick, and bringing them in contact with predisposed
individuals. Among the numerous substrata and
objects in our surroundings, the soil appears particularly
well adapted for such a preservation, and therefore in
many cases it plays a prominent part as a means of
transport, To a less degree the spread of these diseases
is also influenced by a multiplication of the infective
agents outside the body — on nutritive materials, on the
surface of the soil, &c. ; but in our climate this ecto-
genous development and multiplication of the typhoid

3101; E OF SPREAD OF INIECTIYE DISEASES.

and cholera bacilli is of little importance, and lias but
little influence on the mode of spread of the disease,
while on the other hand it plays a more important role
in tropical countries.

Local and The chief fact which Pettenkofer has brought for-

disposition'10 ward in support of his views is the peculiar local and

may be ex- seasonal distribution of cholera and typhoid fever, which
plained with- , . , ,, „

out assuming according to him can only be explained as a result ot

Influence1 of some influence of the soil. It has been already shown
the soil. jn the chapter on cholera, and will be further discussed
below, that such local and seasonal variations in the
distribution of these diseases can be very well explained,
even though we hold to the opinion of the contagious-
ness of both diseases, and only ascribe to the soil the
role of a part of our surroundings, in that like other
substrata it harbours the infective agents given off by
the sick for a considerable time, and then again brings
them into contact with man.

In accordance Having thus arrived at definite views as to the
sotVviewswe various modes of spread of the infective diseases, it is
have to con- easy ^0 group together and characterise the sources of

Rider the •> . . .

following infection in the case of each individual disease, ihe
following is the result in the case of the more impor-
tant infective diseases, omitting those whose mode of
transmission is as yet too imperfectly known (viz.,
leprosy, recurrent fever, dysentery, yellow fever, &c.) : —

a. Contagious Obligatory Parasites.
(a) With slight resisting power.

Syphilis and gonorrhoea : sources of infection, the
fresh secretions.

Rabies : fresh saliva, blood, spinal cord, and brain.

MODE OF SPREAD OF INFECTIVE DISEASES. 737

(ft) With greater resisting power (also transmissible
by various objects).

The acute exanthemata (small-pox, scarlatina, measles,
&c.) : typhus fever. Sources of infection, the morbid pro-
ducts of the skin and mucous membranes. The ex-
citing agents are probably cast off in large quantities ;
they can withstand drying, they adhere to rags, wash
linen, beds, furniture, &c.

Diphtheria : the sputa, membranes expelled by
coughing, secretions of the mouth, secretions from
other mucous membranes attacked by the disease.
The pathogenic agents can probably retain their vitality
in the dry state for a certain time, for how long is as
yet unknown ; they can adhere to the linen, bedding,
floors, soil, &c. We do not as yet possess more ac-
curate knowledge as to the nature of the sources of in-
fection.

Tuberculosis : chiefly the sputa. The spores cast
off in the sputum retain their vitality in the dry state
for about six months. They can adhere to the linen,
clothes, furniture, &c. ; they are also present in tbe
soil under the flooring in a living condition, in the dust
of the streets, &c. In consequence of the large number
of phthisical patients, the number of the infective agents
in the sputa, and their resisting power, the sources of
infection are almost everywhere present.

Glanders : the secretions of the diseased mucous
membranes, and of the ulcers of the skin, furnish the
infective agents in large quantities. According to
Loeffler's recent investigations spores are probably not
formed, for the dry cultivations usually die after some
days or weeks (it was only exceptionally that they were
found alive after three months), and a temperature of
55° C. kills the infective agents in five minutes. The
most important sources of infection are therefore the
fresh secretions and, for some days or weeks, the various
objects to which they adhere. — According to Loeffler a
saprophytic growth of the bacilli does not occur in the
nutrient materials present in the stalls.

47

738 MODE OF SPEEAD OF INFECTIVE DISEASES.

Erysipelas and other human infective diseases of
wounds (puerperal fever, &c.) : secretions of wounds
either in the fresh state or dried on linen, dressings,
bedding, ultimately beneath the floors. In the majority
of cases we do not as yet know how long the infec-
tive agents retain their vitality in the dry state. The
ordinary pyogenic organisms are present in dust, on
clothing, on the surface of the human body, &c.

b. Contagious Facultative Parasites.

Anthrax : 1. The fresh secretions of wounds or of the
diseased mucous membranes, also dressings, clothes, &c.
2. Fasces of animals suffering from intestinal anthrax,
soil and grass impregnated with such dejecta. 3. Pre-
served portions of anthrax cadavers (skin, hair), earth
(or portions of the dwelling, clothing, &c.) which has
come in contact with the blood, organs, &c., during the
post-mortem examination. — In all cases the duration of
the infective power depends on whether or not spores
are formed. There are plenty of opportunities for their
formation outside the living body in a great variety
of substrata, provided the temperature is sufficient.
4. Saprophytic colonies of bacilli growing on the banks
of rivers, &c.

Typhoid fever : dejecta of patients. For the most
part the infective agents are present in the spore form ;
they retain their vitality for a considerable time in a dry
state, at all events up to three months (Gafl'ky) ; they
also live for several months in watery fluids, and in
drinking water. Hence various objects (linen, bedding)
which come in contact with the dejecta may retain in-
fective properties for a long time. It is probable also
that the spores may be preserved for a long time in
the soil (in garden and field earth on which dejecta has
been deposited). — Multiplication can ultimately occur in
nutrient materials, especially in milk, in broth, on
meat, &c.

Cholera : dejecta of the sick. They only retain their

MODE OF SPREAD OF INFECTIVE DISEASES. 739

vitality for a few days under ordinary conditions ; they
die as the result of drying or from over-growth by sapro-
phytes. Hence the most frequent sources of infection
are the fresh dejecta, and the objects contaminated with
them : linen, bedding, water, food, superficial layers of
the soil. — Multiplication can occur on various nutrient
materials, as in the case of typhoid bacilli.

c. Non-contagious Facultative Parasites.

Malaria: probably in marsh water, on the banks of
rivers, on the surface of marshy soil. Nothing more
precise is known.

2. The Modes of Transport.

According to the description given in the preceding Modes of
chapter, the sources of infection are as a rule repre- belbween the
sented by the fresh or dry secretions of wounds, of the

diseased mucous membranes, or of the skin ; further, healthy
by objects and materials in our surroundings contami-
nated by them, especially dressings, linen, clothing,
bedding, the soil under the flooring, drinking water and
articles of food, the most superficial layers of the soil.

From these sources the infective agents may be
carried to individuals capable of taking the infection.

1. By contact between the healthy and sick. The 1. Contact
surface of the body of healthy individuals is brought

into direct contact with the morbid secretions or the ai.c-,k i?rtl"

viduals.

objects harbouring them, by handling the infected per-
sons, or even through a third person. Almost all the
infective diseases can be transported in this way. This
mode of transport is on the whole extremely frequent,
and in the case of many diseases it is the only, or at
least the most important, mode of infection (syphilis,
gonorrhoea, infective diseases of wounds, &c.).

2. By contact with infective animals. The transmis- 2. Contact
sion of the most important zoonotic diseases occurs by )e wee

740 MODE OF SPREAD OF INFECTIVE DISEASES.

diseased

3. Transport

4. Transport

5. Transport
™ J

Influence of

contagious-

noss

contact with the fresh or dried morbid excreta, or with
ol)Jects contaminated therewith, the contact being
brought about by intentionally handling these materials,
by bites, &c.

3. By insects which transport fresh or dried excreta,
or objects contaminated with them, to individuals capable
of taking the infection.

4. By swallowing food or water which contain infec-
^ve germs- This is the most important mode of trans-
port for those infective diseases in which the invasion
only begins from the intestine (typhoid fever, cholera).
Water and food may be directly contaminated by the
infected excreta, or the contamination in the case of the
food may be occasioned by contact, insects, adhering
portions of soil, or infective air germs, in the case of
water by the wash linen, &c.

5. By aerial germs. As has been pointed out above,
the transport by currents of air only occurs in the case
of those infective agents which can withstand drying.
Accordingly it does not come into play in cholera; it is,
further, almost excluded or occurs very rarely in glanders
and some infective diseases of wounds ; on the other
hand it plays an important role in the acute exanthe-
mata, typhus, typhoid fever, tuberculosis.

It is apparent that the last-mentioned mode of trans-
Port has an important influence on the mode of con-
tagion. In cases where it cannot occur the other modes
of transport are much more easy of recognition and
avoidance. We can comparatively readily protect our-
selves against infection by contact by means of careful
cleanliness, and against the introduction of the infec-
tive agents by food and water, by careful selection and
preparation of the nutriment, and direct transport by
infected animals or insects occurs on the whole very
seldom. On the other hand, transmission by currents
of air occurs in an unnoticeable manner and one against
which no protection exists, and it may extend over
considerable distances ; the infective agents which are
transportable in this way may also infect individuals
who do not come into immediate contact with the sick

MODE OF SPREAD OF INFECTIVE DISEASES.

or with infectious objects. The number of infections
caused by them is under certain circumstances much
greater and more widely distributed. That all the
diseases belonging to this group do not in practice show
an equally high degree of contagiousness, — that, for
example, the acute exanthemata and typhus fever are
extremely contagious, while in typhoid fever and tuber-
culosis the danger of contagion is much less, — is explained
by the other conditions necessary for infection ; for ex-
ample, by the situation of the seats of invasion and by
the individual predisposition. These two conditions
are referred to more in detail in the following pages.

The detachment of the infective agents from their Conditions for
substrata and their passage into the air occurs from the air"81
dried excreta and the various objects to which they
adhere — from clothing, from the flooring, from the sur-
face of the soil. In all cases complete dryness of the
surface is a necessary condition for the detachment of
the infective germs; hence in the soil this only occurs
when a drying zone is present, and when the most super-
ficial layer is in a state of dust.

It frequently happens that the same mode of transport indirect trans-
does not carry the infective agents directly from the source P<
of infection to the point of invasion, but that it carries
them in the first place to another means of transport.
Thus, for example, the detached infective agents may be
carried by currents of air to articles of food, and from
thence reach the exposed individual.

3. The Seats of Invasion.

Before we can arrive at definite ideas as to the im- Do the skin
portance of the seats of invasion for the spread of the
infective diseases, we must decide the question whether

the bacteria can penetrate the various surfaces of the the entrance
body, the skin, and especially the mucous membranes,
when these are in a normal condition ?

742

MODE OF SPREAD OF INFECTIVE DISEASES.

This question
was formerly
answered in
the affirmative
in the case of
the intestine
and lung's.

The .sapro-
phytes are
supposed to
die in the
Wood.

This assump-
tion is in-
correct,

This question has or the most part been answered in
the affirmative. The passage of oil globules through
the walls of the intestine, and the enormous surface and
delicate epithelial covering of the lung, has been promi-
nently pointed out ; and the constant entrance of sapro-
phytic bacteria, and the occasional passage of infective
agents into the interior of the body, especially into the
circulating blood, has been assumed. Pettenkofer has
indicated the lungs as the chief organ through which
the pathogenic bacteria pass into the blood ; according
to the view generally held, they are then carried from
the lungs to those parts of the body in which the local
affections characteristic of the disease in question usually
appear. Thus the infective agents of cholera and typhoid
fever, when they are inhaled, are supposed to pass
through the lungs into the blood, and from thence into
the mucous membrane of the intestine, where they
multiply and set up the specific alterations.

The fact that no bacteria have been found in the
interior of the healthy body in various careful investiga-
tions is opposed to the view that saprophytic bacteria are
constantly penetrating into the normal body from the
lungs and intestine. Von Fodor and others have, how-
ever, sought to explain this contradiction by the assump-
tion that the saprophytic organisms which pass into the
body are rapidly destroyed in the blood.

Such an explanation is, however, no longer admissible
after the researches of Wyssokowitsch, to which we have
previously alluded. These investigations have shown
that a great variety of bacteria are not destroyed in the
circulating blood, but retain their vitality in the interior
of certain organs for several hours, days, or even months.
If, therefore, there were a constant passage of bacteria
from the lungs and intestines into the blood, we must
undoubtedly frequently find them in considerable n am-
bers in the interior of the body, and the resistant subtilis
spores which are always present on the surface of the
body would gradually accumulate in the body.

As the result of these experiments it is very impro-
bable that bacteria can pass through the mucous mem-

MODE OF SPREAD OF INFECTIVE DISEASES. 743

branes and lymphatic glands, and ultimately reach the
blood. It is probable also that pathogenic bacteria behave
in this respect in the same manner as the ordinary in-
tants of the surface of the body; for the excreting
membranes of the animal body (kidneys) are just as
impassable for the numerous kinds of pathogenic bacteria
as for the saprophytic organisms.

Nevertheless it was desirable to make direct experi- Direct experi-
ments as to the passability of the walls of the lungs and

of the intestine by bacteria ; and experiments of this °f the lungs

. . x and the mtes-

kind have been carried out in large numbers by Wysso- tine by
kowitsch during the course of last year in the author's bactena-
laboratory. From these experiments, which will be
shortly published in the Zeitschriftfur Hygiene, it follows
with complete certainty that neither the surface of the lung
nor of the intestine permits the direct passage of bacteria
into the blood, so long as the mucous membrane is intact;
even if small lesions of the mucous membrane are pre-
sent, the bacteria do not as a rule reach the blood, but
remain in the neighbouring lymphatic glands. — In the Intestine.
experiments on the intestine, staphylococcus aureus,
bacillus indicus, and spores of subtilis were employed;
the cultivations were given in large quantities as food,
and it was found that the bacteria did not suffer any
injury from the gastric juice; but in order to be more
certain as to this point, they were in some cases injected
into loops of intestine isolated by ligatures. In no case,
however, were the bacteria found in the organs which, as
had been previously ascertained, always preserved any
germs which had really reached the blood; while, on the
other hand, they were always found when even only very
small quantities of the same bacteria were introduced
into the blood or into the peritoneal cavity. In the
experiments with loops of intestine, small injuries of the
intestinal membrane were unavoidable; and then the
bacteria in question could be found in limited numbers
in the corresponding mesenteric glands, but did not pass
beyond them.*

* Eibbert (Deutsch Med.Woch., 1885, Nr. 13) andBizzozero (Centralbl.
f. d. iued.\\roch., 1885, Nr. 45) found various kinds of bacteria in healthy

744 MOPE OF SPREAD OF INFECTIVE DISEASES.

Lungs.

There is no
passage of
bacteria
through the
lungs and in-
testine.

invasion of

troduction of

bacteria into

the blood.

Experiments as to the passability of the surfaces of
the lungs were made by causing the animals to inhale
either the dried cultivation in the form of dust, or a fluid
cultivation in the form of spray; or the material was
injected into the trachea in small and repeated quantities.
Here also no passage of the bacteria into the blood was
observed, even when the lung tissue had undergone
pathological changes as the result of the injections. —
These results harmoniso entirely with those obtained by
Arnold, who found by very numerous and careful investi-
gations that minute bodies (soot, ultramarine, &c.), when
inhaled do not pass into the blood or organs of the body,
but at most only reach the neighbouring bronchial glands.
Arnold has ascertained by accurate microscopical investi-
gations that the human lung does not behave differently
to that of animals as regards its passability to minute
elements ; soot does not pass into the internal human
organs by normal preformed paths, but only by abnormal
ways.

Hence we have given up the former view that bacteria
can pass readily into the blood, and from thence into
the organs of the body through the intact lungs or the
normal intestine ; on the contrary, the body of warm-
blooded animals nowhere offers a surface permeable by
infective agents, so far as is as yet known, unless im-
portant alterations of the normal tissue have previously
occurred.

One mode in which an infective agent can enter the

r blood and the internal organs of the body is when a

large opening is present which permits its direct passage

i i i i * i j t ,1 i •

into the blood ; lor example, a wound 01 the skin or
mucous membrane communicating with a blood vessel.

animals in the follicles of the processus vermiformis and of the
sacculus rot. at the entrance to the caecum, which had evidently pene-
trated from the lumen of the intestine ; they did not appear to be alive
in the deeper layers of the follicles, and could not be traced beyond
the follicles. This occurrence of bacteria at one special part of the
intestinal mucous membrane, together with the constantly negative
results obtained in other parts of the intestine, and with the evident
death of these bacteria in the deeper layers, quite corresponds with
the results of Wyesokowitsch's experiments.

MODE OF SPREAD OF INFECTIVE DISEASES. 745

This is a mode of infection which we frequently produce
artificially in our experiments on animals, but which
seldom occurs under natural conditions. The experiments Even then in-

. , . . f f ection does

on animals, however, teach us further that in many mtec- not aiways
tive diseases the penetration of the infective agents into occur-
the hlood is not sufficient for the production of infection;
we see that the bacilli of pneumonia, of malignant oedema,
of cholera, the micrococci of erysipelas, &c., do not cause
disease when injected into the hlood, with suitable pre-
cautions against the entrance of other bacteria, such as
disinfection of the wound in the skin, while they are
virulent in the same animals when introduced into
other parts, such as into a wound of the lung, into a
wound of the skin, into an altered intestine, &c. This
is explained in part by the fact demonstrated by Wysso-
kowitsch that bacteria circulating in the blood are not
excreted through certain surfaces of the body, such as
the wall of the intestine, and cannot pass into the
lumen of the intestine, for example, except when haemor-
rhages occur in the mucous membrane ; and that there-
fore cholera and typhoid bacilli, even when they have
penetrated into the blood, do not always reach their
proper seat of action. Wyssokowitsch's experiments
also give a partial explanation, these experiments show-
ing that the endothelial cells of the capillaries have the
power of fixing and destroying bacteria circulating in
the blood ; hence only those bacteria which are able to
overcome this protective arrangement can set up disease
from the blood. In the case of those resistant infective
agents which can penetrate with the blood into various
organs, and multiply there or in the blood itself, injection
into the blood is a very active mode of infection, e.g.,
in the case of the exciting agents of septicaemia, anthrax,
and tuberculosis.

Besides this infection through the blood, which occurs Or the infcc-
comparatively seldom, infection evidently occurs in many eirteratn
dieases by the primary establishment and development ^^af1^1^
of the infective agents at those parts of the body in wards become

T • -I ,i -c i ., the seat of the

which the specific process occurs or begins ; so that the future disease.
seat of the alterations characteristic of the infective

746 MODE OF SPREAD OF INFECTIVE DISEASES.

disease in question coincides with the specific seat of
invasion. Erysipelas develops in the lymphatic channels
of the skin ; wounds of the skin which open an entrance
to these channels form the points of invasion of the
erysipelas cocci : gonorrhoea establishes itself only on
the urethral and conjunctival mucous membrane, and
these are likewise the seats of invasion of the gonococci :
pneumonia is limited to the lungs, and there the in-
vasion of the infective agents must begin : typhoid and
cholera localise themselves in the first place in the
intestine (leaving out of account the secondary deposits
of the typhoid bacilli), and here we must look for the
seats of invasion of the infective agents. If typhoid
bacilli are introduced into the lungs, pneumonia bacteria
into wounds in the skin, gonococci on the intestinal
mucous membrane, there is no result even when small
wounds and injuries are present.

Some infective agents can set up a primary specific
disease in several different organs of the body ; for
example, anthrax in wounds of the skin, in the intestine,
in the lungs ; tuberculosis likewise in the lungs,
intestine, genito-urinary system, &c. ; diphtheria on
various mucous membranes. In the case of these
diseases the points at which the infective agents can
enter are therefore correspondingly more numerous.

In the case of the acute exanthemata it is probable
that the skin or the surface of the mucous membranes
are the parts which are specially predisposed for the
development of the infective agents, and it is also pro-
bable that these parts are the seats of invasion of other
as yet unknown infective agents.

These points We must next inquire whether these points of in-
pormlt th? vasion peculiar to the various kinds of infective agents
entrance of permit the establishment and development of these

bacteria either L . , .

when in a agents when the tissues are in the normal condition, or
normal n- ^^her solutions of continuity of the skin or mucous
membranes must be present to enable the infective agents
to penetrate. It is conceivable that some infective
agents do not require any preparation of the seat of
invasion, but only that they should be protected while

MODE OF SPREAD OF INFECTIVE DISEASES. 747

developing in folds and recesses of the mucous membrane,
and not be readily removed with the mucus or overgrown
by saprophytes. In such situations the parasites might
be able to multiply to a certain extent, and then lead to
a production of toxic materials which would be sufficient
to destroy the neighbouring cells, and thus allow them
to penetrate more deeply into the tissue. Such penetra-
tion through normal skin and mucous membrane must
be assumed, more especially in the case of the infective
agents of the acute exanthemata, which often attack very
numerous individuals.

Other infective agents, on the contrary, probably require Or the infec-
minute lesions or solutions of continuity of the mucous

membrane in order to obtain a firm footing in the tissue, lesions at the
and multiply at first at the cost of the dead cell material, aion.
and spreading from that point carry on the struggle
against the living cells. In all cases, however, the
presence of such minute injuries favours the entrance of
all infective agents and increases the individual predis-
position (see below).

The fact that a specific and exclusive seat of invasion importance of
is necessary for each infective agent evidently is of great * ofnt^eof ?nva
importance as regards the mode of spread of the infective sion for the
diseases. For the transmission of this group of diseases
it is evidently not sufficient that the means of transport
should carry the infective agents from the source of
infection to some part or other of the body, but
it is also necessary that they should be brought to
a particular situation. In the case of cholera and
typhoid the disease must therefore occur chiefly as the
result of swallowing infected water and infected food ; it
is possible that the germs may also reach the mouth by
contact or by the inspired air, but it is only in relatively
few cases that a sufficient number of the infective agents
will pass in this way in a living state through the
stomach into the intestine.

It is further evident that the position and other con- influence of
ditions of the specific points of invasion must have a
great influence on the danger of infection. Although invasion
the spores of the typhoid bacilli are probably more

748 MODE OF SPREAD OF INFECTIVE DISEASES.

resistant than the infective agents of the acute exanthe-
mata, and although both are produced in large quantities
and distributed in the surrounding world by the patient,
the latter are, nevertheless, incomparably more contagious,
because the unprotected surfaces of the body can be
readily invaded by them, and these surfaces are very
easily infected by contact or by currents of air ; on the
other hand, in the case of typhoid fever we usually have
to do with a limited mode of transport by means of im-
perfectly prepared food and of impure water, and the
seats of invasion are difficult of attack and provided with
a protective arrangement ; in this case also currents of
air can only exercise an influence as a means of trans-
port in so far as they curry the specific infective agents,
in the first place to the food, and under favourable con-
ditions by means of the food to the intestine.

In the case of some infective agents which are as yet
but little known (malaria, relapsing fever, &c.), we can
scarcely put forward any hypotheses as to whether
specific points of invasion are present at all, or where
they should be looked for.

4. Individual Predisposition.

Unequal pre- Experience has long ago taught us that the different
different011 °f infective agents are not equally dangerous to all kinds
species and of of warm-blooded animals, but that the one can affect only

different m- .

•HvMnais. this, the other only that species. Closely allied species
and races of animals often show in this respect the
most striking differences ; thus the bacillus murisepti-
cus kills without exception every house-mouse inoculated
even with the most minute quantity, while field-mice
are not at all affected even by large doses ; and the
micrococcus tetragenus is only infective for the white
variety of house-mice, while it is not infective for the
grey variety. — But even among the individuals of one
and the same species similar differences exist ; and the
infective organisms which are peculiar to man attack for
the most part only a certain number of predisposed in-

MODE OF SPREAD OF INFECTIVE DISEASES. 749

dividuals, while others equally exposed to the attack of
the infective agents are not affected, in other words are
immune.

As to the causes and the meaning of this individual
predisposition and immunity we know as yet very
little, but the results of a large number of experiments
on animals give us some insight into the behaviour of
the infective agents in the body. Further investiga-
tions must, however, be made on these points before we
can come to any very definite conclusions. The factors Factors which
which influence the predisposition of the body lie partly flnence.
in the body itself, in the constitution of its cells, secre-
tions, &c., and come partly from without, these external
factors aiding the infective agents in that they render
the body abnormally susceptible to attack.

In the first place it may happen that the access of Protective
certain infective agents to their specific points of invasion agSnft thT S
is rendered difficult by the natural protective arrange- S^^ctCTiato
ments of the body ; thus the gastric juice can, according certain points
to its degree of acidity, and according to its quantity, °
injure those infective agents which must develop in the
intestine ; and this injurious action may be present to
a greater degree in one species of animal, or in one
individual than in other individuals, where the infective
agents more easily pass this protective arrangement. —
Further, as regards those infective agents which have
their seat in the lungs, the more or less narrow and
convoluted entrance to the respiratory tract, the ciliated
epithelium, and the sensitive mucous membrane form a
protective arrangement of varying efficacy, and according
to the development of these arrangements the one species
or the one individual will have an advantage over the
other as regards the ease with which parasitic bacteria
can enter the lungs.

Further differences in the constitution of the points Differences in
of invasion even of an apparently trivial character must the characters

. ' a r™ -, • of the Points

exercise a very important influence. Thus according to of invasion
species and race, according to the age and state of the:Tlselves-
nutrition of the individual, &c., there are probably
differences in the skin, in the mucous membrane, and

750 MODE OF SPREAD OF INFECTIVE DISEASES.

especially in the epithelium, which, although scarcely
noticeable, have nevertheless a marked effect, and permit
or prevent the growth of the infective agents. Loeffler,
in his investigations on diphtheria, has brought forward
a very beautiful experimental proof of the importance of
the character of the epithelium ; he showed that young
guinea-pigs could be infected in the vagina by cultivations
of the bacilli of diphtheria, evidently because the epi-
thelium of the mucous membrane is extremely delicate
and easily injured ; older animals, whose vagina is pro-
tected by tough epithelium, were, on the contrary, quite
insusceptible to this mode of inoculation. — The variation
in predisposition in accordance with age which is seen
in various human infective diseases, must probably be
in part referred to a similar influence of the epithelium
at the point of invasion. Further, many facts point to
the view that even the very slightest pathological altera-
tions or loosening of the epithelium, such as usually
occurs in catarrhs for example, also render infection
easier.

influence of Further, the condition of the other more deeply
the other cells. p]ace(j ce]}s of the affected organ is also of importance
for the occurrence of the disease. The endothelial cells
of the capillaries, and to a very marked extent in some
organs the cells of the lymphoid tissue, appear to play
an important part in the battle with the attacking
bacteria, and on the vital energy of these cells the result
of the battle — its rapid termination before general infec-
tion occurs, or its continuation in ever-increasing dimen-
sions— will depend to a very marked degree. In the
case of the endothelial cells of the blood vessels it can
be experimentally shown how a general depression of
the cell energy by poisons, and especially by ptomaines,
leads to a totally different ending to the battle in which
in the normal condition these cells are, in the case of
certain species of bacteria, always victorious ; it can be
shown that, under the influence of ptomaine poisoning,
the same bacteria which formerly quickly died in the
endothelial cells, and never caused disease in the
animals, are now able to multiply extremely rapidly in

MODE OF SPREAD OF INFECTIVE DISEASES. 751

the blood and cause the death of the animals which
were previously immune (Wyssokowitsch).

Not uncommonly small injuries due to the most External in-

. , . . ,, . . fluences ; in*

various causes seem to prepare the points of invasion juries at the
for the reception of the infective agents, and to pave the gjjtsof inva"
way for their growth. Experimental proof of this mode
of predisposition has been recently brought forward by
Orth and Wyssokowitsch ; these investigators were able
to set up typical endocarditis in rabbits by first causing
trivial lesions of the cardiac valves, and then injecting
cultivations of staphylococci ; on the other hand, the
infection did not succeed when the cultivation was
injected without simultaneous injury of a valve.

In the intestinal mucous membrane predisposing
injuries of this kind may at times be caused by animal
parasites, by sharp and pointed constituents of the food,
&c. It is possible also that other, though not truly
infective, bacteria, which, however, when they multiply
to a marked extent in the intestine produce consider-
able quantities of ptomaines, and by means of these
cause irritation of the intestinal mucous membrane with
loosening of the epithelium, may be able to prepare the
soil for the true infective agents, and thus give rise to
predisposition.

It is evident that the various factors just mentioned importance of
present such manifold though slight differences that the ^e^doc^ t0*Q
different behaviour of individuals and species is very diseases.
easily intelligible. It is true that these — and especially
the individual differences — do not play an equally
prominent part in the case of all the infective agents ;
the more exposed the points of invasion, the more exten-
sive and numerous they are, and the more energetically
the infective agents in question are able to overcome
the resisting power of the cells, so much the less will
individual predisposition come into play. These con- slighter in-
siderations seem to be especially applicable in the case &^edis 0°fit{'^
of the acute exanthemata of man, and hence the danger in the acute
of infection in these diseases is much more general than c"
in other cases where the exciting agents, although they
possess the same or even a greater degree of resisting

752 MODE OF SPREAD OF INFECTIVE DISEASES.

power, and can be distributed by the most various modes

of transport, establish themselves, however, chiefly in

the lungs or in the intestine, — in other words, in places

which are protected by special arrangements against the

entrance of infective agents in a manner varying in

individual cases ; and the danger of contagion is still

less when the energy of the infective agents is so slight

as compared with that of the cells of the body that they

can only reach the place of their development when the

epithelium has been specially prepared and weakened.

Influence of The influence of individual predisposition is most

tionTn the081" strikingly seen in the case of tuberculosis ; in this

spread of disease we learn from experience that the greater or

tuberculosis. x

less accumulation of resistant infective agents in human
surroundings plays a relatively subordinate part in the
spread of the disease ; on the other hand, the state of
the protective arrangements at the points of entrance,
and especially the state of nutrition of the mucous
membrane, has such a definite and important influence
that it has become the rule to pay the greatest attention
to the removal of the individual predisposing factors (by
good nourishment, increased respiratory movements,
&c.), and not to attempt the careful removal of the
infective agents, as is done in the case of other infective
diseases.

5. Acquired Immunity and Protective Inoculation.

Of special importance is the immunity acquired as
the result of recovery from the same disease, or from
one caused by similar or attenuated exciting agents.
Relapsing Such immunity is not acquired in the case of all

infective diseases. Erysipelas, pyaemia, gonorrhoea,
relapsing fever, pneumonia, and malaria, frequently
show relapses even within a short time after recovery
from the first attack. Other diseases are followed by
immunity for some time, but never without exception,
nor to a similar degree, in the different species of
animals ; for example, anthrax may occur repeatedly in

MODE OF SPREAD OF INFECTIVE DISEASES. 753

man and horses, while sheep and cattle seem to be pro-
tected by one attack of the disease. Cholera, as a rule,
gives protection for some years against a second attack ;
nevertheless even in this case exceptions not un-
commonly occur. A marked immunity, lasting for a Varying
long time, follows a single attack of the acute exanthe- acquired*
mata, and of typhoid fever. immunity.

In the case of those diseases which produce immunity,
even though for a short time, it almost always happens
that the second attack runs a milder course, and often
occasions only a very trivial disturbance of the general
condition. Nevertheless the length of time between the
two attacks may, according to the nature of the infective
agent, completely neutralise this effect.

Further, it is important to note that in the case of
many diseases the severity of the attack seems to be
almost of no importance for the production of immunity.
In the case of the acute exanthemata, typhoid fever,
cholera, &c., we often observe remarkably mild cases, in
which there is only a trivial local development of the
infective agents at the seat of invasion, and yet recovery
from such affections, which can scarcely be called dis-
eases, may lead to immunity against the infective agent
in question. — Nevertheless, in other diseases we are
able not unfrequently to trace a relation between the
degree of the immunity and the severity of the disease.

An explanation of the peculiar phenomenon of acquired Former
immunity cannot at present be given on the basis of experi- attempts to
ments. Numerous attempts have been made to furnish an acquired^
explanation. Thus Klebs and Pasteur assume that in the immunity,
first attack of the disease some material that is necessary for
the life of the pathogenic fungi has been removed from the
body, and that the body thus acted on no longer offers a suit-
able soil for the development of the organism at a subsequent
period. But the results of our cultivation experiments and
all our biological experience contradict, on the one hand, the
idea of such a sensitiveness of pathogenic bacteria towards
minute quantities of an unknown nutrient material, and
on the other the probability that such a state of matters
should be kept up for years in the living body. — Chauveau,
Wernich, and others have assumed that those products of the
life of the bacteria which are noxious to the organisms them-

48

754 MODE OF SPREAD OF INFECTIVE DISEASES.

selves may remain for a long time in the body, and thus
afford a protection against subsequent invasions. But this
disinfecting power of the products of the bacteria, which has
been often insisted upon, appears, according to the accurate
experiments of Sirotinin, to be in most cases a fable, or at
any rate to be much exaggerated; and, on the other hand,
such a stubborn retention of minute quantities of this bacterial
poison in the living body does not at all correspond to our
ordinary physiological ideas.— Grawitz sought to explain
immunity by supposing that as the result of the battle
between the cells of the body and the pathogenic organisms,
the vital energy and the assimilating power of the animal
cells is increased as compared with that of the parasites ; and
that the duration of the immunity is occasioned by the trans-
mission of this increased physiological energy from one cell
generation to another. But in this case it would be very
difficult to understand why it is always only the same or
similar infective agents which occasion a sufficient increase
of the cell energy.

Assumption of A better view, and one more in correspondence with
alteration^ ^e views developed in the preceding pages, as to the
the seat of mode of entrance of the infective agents, is that put for-
ward by Buchner, viz., that that organ which is associated
with the development of the specific infective agents
undergoes a reactionary alteration of its tissue under the
influence of the bacteric development, and that this lasts
for a long time, and does not permit a second develop-
ment. Wolff berg has put forward a similar hypothesis
with regard to the origin of the immunity against small-
pox after vaccination. Wolff berg asserts that the altera-
tions which lead to the immunity must occur in the skin,
as being that organ which forms the first and most im-
portant point of attack for the infective agents ; and he
tries to point out the probability that the causes of the
immunity are chiefly the destruction of the weak cells of
the rete, and the retention and development of the more
resistant elements.

On the assumption of a reactionary alteration of the
specific seats of invasion, we can understand that it is
only the infective agents of the same disease, or of
one similar to it (or only weakened agents), which arc
able to give immunity against a later attack by the same

MODE OF SPREAD OF INFECTIVE DISEASES. 755

organisms. Only those parasites which have exactly the
same seats of invasion can come into play in causing a
reactionary alteration of these seats. — It further becomes
intelligible that complete immunity against later in-
vasions is at times obtained by locally limited affections
which have caused an almost unnoticeable disturbance
of the whole body, for it is only a certain local affection
of the seats of invasion which seems to be of importance
for the production of the immunity. — It is to be hoped
that experimental investigations will soon afford a more
sure basis for the attempt to explain immunity ; as yet
the explanations are quite hypothetical, and do not meet
all cases, but only apply to that group of infective dis-
eases which have specific points of invasion.

The experience as to the action of pestilences, and Protective in-
more especially the knowledge of the protective effect of ot
vaccinia against small-pox, which has been gained by ex-
periments on millions of men for almost 100 years, have
demonstrated that the acquired immunity is in many
respects the most important factor in preventing the
devastating action of the infective diseases. In vaccina-
tion we artificially transmit organisms which are remark-
ably like the infective agents of small-pox, but which
excite in man only a mild and local disease. By this In variola,
inoculation we can prevent the invasion of virulent in-
fective agents of the same kind ; and such a vaccination
is of great value, especially for variola, because, as we
know, one attack of this disease gives a very long con-
tinued and certain immunity ; because, further, the at-
tenuated vaccine material preserves its slight degree of
virulence with great constancy ; and because as a result
we need neither fear injury from the inoculation, nor
uncertainty in the result.

During recent years only few, and at the same time
crude and uncertain attempts have been made to extend
protective inoculation to other infective diseases, espe-
cially in the case of domestic animals, but since the year

756 MODE OF SPREAD OF INFECTIVE DISEASES.

In chicken
oholera.

1880 there has been a very active movement in this
direction with the aim of providing an extensive appli-
cation of protective inoculation.*

The starting point of this movement was Pasteur's
discovery that the microbes of chicken cholera could be
artificially attenuated, and that the inoculation of these
attenuated bacteria caused a local affection in fowls, after
recovery from which they were found to be immune
against inoculation with the virulent infective agents of
fowl cholera. On page 317 a more minute description of
Pasteur's experiments is given ; we need only add here
that two vaccines have been employed in practice, of
which the first is more, and the second less attenuated ;
the first vaccine is injected by means of a Pravaz syringe
at the tip of the wing of fowls, and the second
vaccine is employed twelve to fifteen days later. As a
result the animals are said to be protected against the
virulent bacteria. Kitt was, however, unable to confirm
Pasteur's results as regards the protective action of these
inoculations. And even if the action of the vaccine were
prompt, it is very seldom that it could be of practical
value in view of the usually very rapid spread of the
disease in the hen-houses which are attacked, and of the
length of time which must elapse till the protective in-
oculation is completed. The value of the inoculation is
also correspondingly less, because by proper disinfection
of the hen-houses a much more reliable prophylaxis can
be obtained.

The method of protective inoculation with the artifi-
cially attenuated infective agents was then attempted in
ohe case of anthrax, symptomatic anthrax, and swine
In swine fever, fever. The methods employed in the two last diseases
have been already described on pages 300 and 307 ; it
was there shown that the practical value of the inocu-
lations against swine fever is as yet extremely doubtful,
while the results in symptomatic anthrax are more

* While these pages were passing through the press a very valuable
paper has been published by Kitt under the title \\'ert und Unwert der
Schutzimpfungen gegen Thierseuchen, Berlin, 1886, to which we must
refer the reader for all the details with regard to protective
inoculations.

In symptom-
atic anthrax.

.MODE OF SPREAD OF INFECTIVE DISEASES. 757

favourable ; but here also we cannot yet come to a final
judgment on account of our ignorance of the length of
duration of the protection, the absence of a calculation
as to the cost, and the neglect up to the present time
of other prophylactic measures in the infected districts.

The inoculations for anthrax have excited special in anthrax,
interest. They were carried out in the first place with
bacilli attenuated by Toussaint's method (p. 657); a
practically useful vaccine was later produced by Pasteur
and Chauveau, each by a different method. Pasteur Pasteur's
employed as his first vaccine a cultivation in meat m
infusion which had been kept at a temperature of 42°
to 43° C. till it no longer killed guinea-pigs and rabbits,
but was still fatal to mice (see page 657). One
division of a Pravaz syringe of this vaccine is injected on
the inner side of the hind thigh of sheep ; in the case of
cattle two divisions are injected behind the shoulder.
After the lapse of twelve to fourteen days a similar in-
jection is made with the second vaccine, which has been
kept at 42° to 43° C. till rabbits are not killed by it,
while mice and guinea-pigs still die. It was not till
Koch introduced the method of testing the cultivations
on these three kinds of animals that it was possible to
know exactly the degree of virulence of the organisms. —
Chauveau makes his vaccine by heating the organisms
for a shorter time at higher temperatures ; he em- m
ploys fresh anthracic blood and not cultivations, and in
order that it may be warmed as quickly as possible, he
collects it in very small glass tubes. More recently
Chauveau, in conjunction with "Wosnessenksi, has also
utilised for the purpose of attenuation the simultaneous
action of high pressure (page 660). The virulence of
his vaccine lies somewhat between that of the two vaccine
materials employed by Pasteur ; it is chiefly intended for
cattle, and they are inoculated in the ear by means of a
syringe. — The other methods of attenuation and protec-
tive inoculation for anthrax have not as yet been intro-
duced into practice.

In judging of the results obtained we must, in the
first place, note that the effect of the protective inocu-

758 MODE OF SPREAD OF INFECTIVE DISEASES.

Value of the lation differs in different species of animals : for example,

protective in- . _ . L

oculation for guinea-pigs and rabbits cannot be made immune by the
attenuated anthrax bacilli ; rats often resist inoculation
with the virulent material, but do not thereby acquire
immunity. In like manner the effect is different in
sheep and cattle, the two species of animals chiefly in-
oculated in practice. In the case of sheep the protec-
tive inoculation appears to be particularly uncertain in
its results ; too weak vaccines do not give the necessary
guarantee for immunity ; too strong materials, on the
other hand, readily cause the death of the animal ;
further, the duration of the protection is very short,
probably not lasting more than a year; and it has also
been shown by Koch that sheep inoculated with strong
vaccines are not able to resist natural infection produced
by feeding them with anthrax spores. — In the case of
cattle the result is probably more favourable, because
stronger vaccines can be borne, the losses by the inocula-
tions themselves are less, and the chances of immunity
are better. Nevertheless even here we cannot make any
definite statements as to the duration of the protection,
nor as to its potency against the natural modes of in-
fection. In any case the strong vaccines present a
certain amount of danger for the people who have to
attend on the animals, and without doubt these protec-
tive inoculations can only be looked on as a temporary
means to be employed till rational means of prophy-
laxis, proper modes of disinfection, change in the pas-
ture, care in burying the dead bodies, &c., have been
generally introduced.

Protective in- The protective inoculation which has most recently
oculation attracted attention is that employed by Pasteur against
Method/' rabies. When the method of attenuating the rabic
virus described on page 660 had been ascertained,
Pasteur attempted to rentier dogs immune by first in-
oculating them with virus which had been dried for the
longest time, and which was the weakest ; then two days
later less virulent material was used, and so on till
finally the virulent virus was employed. — When these ex-
periments had led to uniform results. Pasteur made pro-

MODE OF SPREAD 0? INFECTIVE DISEASES. 759

tective inoculations on persons who had been bitten by
dogs which were stated to be rabid. His method con-
sisted in injecting into the patient on the first day a
Pravaz syringeful of an emulsion prepared by the aid of
sterilised infusion from a portion of the spinal cord of a
rabbit which had died of rabies, the cord having been dried
for fourteen days; on the following day a mixture from a
piece of spinal cord dried for twelve days was injected ; on
the third day a cord eleven days old was used, and so on,
till on the twelfth day a virulent material which had been
preserved for only one day was employed.

By this method hundreds of people have been treated Eesuits of the
in Pasteur's laboratory, and the number is still increas- ^uiatiol6 in~
ing. However, of these some have died of rabies
shortly after the treatment, and others at a later period.
It is difficult to decide with certainty whether the
percentage of those who have died after inoculation
is smaller than of those who die when no protective in-
oculation is used, as among those who have been treated
by Pasteur there is a large number who were, it is true,
bitten by dogs, but in which there was no certainty that
the dogs were mad. It is nevertheless probable that a
much smaller percentage of those persons who have been
inoculated have died as the result of the bite than of those
not inoculated, and, therefore, that the protective inocu-
lation has had the desired effect in a large number of
cases. But this result is far from being a certain and
constant one, and in addition to the uncertainty of the
•effect, we have on the other hand the danger that per-
sons who were not infected by the bite, and who would not
therefore have died of rabies, may have been infected by
the inoculation itself. In some of the fatal cases which
have followed the preventive treatment, the suspicion
of such an unintentional production of the disease can-
not be entirely put aside.

On the whole an unbiased person will receive the Differences
impression that Pasteur's discovery, which is of un- protective in-
doubted scientific value, has been introduced into prac- rabJe^am/01
tice too hurriedly. As contrasted with the preparation other modes of
of other vaccines, the method of attenuation is difficult oovlatUm! *

760 MODE OF SPREAD OF INFECTIVE DISEASES.

to control, and does not sufficiently guarantee the degree
of virulence. Further, the whole process of protective
inoculation against rabies completely differs from
former protective inoculations for small-pox, anthrax,
symptomatic anthrax, and swine fever, and also from
the experiments made on dogs with the rabic virus, and
which served as a proof of the utility of the method,
for the people which were inoculated by Pasteur were
already infected by the virulent disease. In all
the former protective inoculations which might be
thought to be analogous, the preventive means were
employed before the infection, and experience has taught
us that inoculation with vaccine lymph, for example,
has no effect if infection with variola has occurred before
the vaccination was performed. In like manner the
dogs experimented on by Pasteur, with regard to which
accurate numbers have been published, were not infected
before the protective inoculation. Pasteur mentions,
however, that he has attempted subsequent protective
inoculation on dogs which had been previously bitten or
infected with virulent material ; but accurate numerical
details of these most important experiments have not
been given, and hence the suspicion arises that in these
experiments the result obtained has been as little con-
stant and certain as those which have followed the in-
oculations on infected individuals.

A more thorough scientific study of the matter in
various directions would, therefore, have been at all
events desirable before the method was introduced into
practice. It is very possible that the method in its present
form, being so difficult of control, may, if employed ex-
tensively and by less experienced hands than those cf
Pasteur and his assistants, lead to many serious mishaps.
General value In conclusion, neither the inoculation for rabies, nor

of protective , -i ,-1 , ' . . ,

inoculations. tne otner modern protective vaccinations, represent the
ideal of a satisfactory prophylaxis against the infective
diseases. Even the valuable vaccination for small-pox
has not been generally introduced without difficulties,
and yet in the case of variola we have to do with a
disease which, on account of the number and resisting

MODE OF SPREAD OF INFECTIVE DISEASES. 76 1

power of the sources of infection, on account of the easy
transportation of the infective agents, and on account
of the readiness with which the body is attacked, can he
influenced with extreme difficulty by other prophylactic
means. It is further a disease which is very specially
suitable for a protective inoculation on account of the
peculiar certainty and persistence of the immunity. On Advantages of
the other hand, in the case of the majority of other in- p
fective diseases, it is decidedly more rational to aim at means-
the destruction of the infective agents, and the preven-
tion of their spread or invasion, than to rely on an un-
certain protective inoculation. That in the case of
rabies suitable prophylactic rules deserve by far the
greatest confidence is shown most distinctly by the con-
dition of those countries in which a high tax on dogs,
stringent rules against stray or possibly rabic animals,
and under certain circumstances compulsory muzzling,
have been already introduced ; statistics show that in
these countries (Prussia, Bavaria, &c.) the deaths from
rabies in dogs have diminished to a marked degree, and
in man have practically disappeared.

6. The Local and Seasonal Predisposition to Infective
Diseases.

From the foregoing considerations as to the mode of irregular
spread of the infective diseases, we may draw the con- t
elusion that this distribution cannot occur either equally diseases
over a large area or in an unbroken course as regards time,
but that seasonal and local variations must appear and
exert an influence on the occurrence of these diseases.

In none of the infective diseases is the spread of the
infective agents like that of a gas which diffuses itself
equally in all directions, and over great distances ; on
the contrary, the effective agents, even in the most
favourable cases, only spread equally from one centre
over a small distance. Even the most typical con-
tagia, viz., the exciting agents of the acute exanthe-

762

MODE OF SPREAD OF INFECTIVE DISEASES.

Multiplicity
of the local
and seasonal
variations.

mata, are not distributed over a wide area by means
of currents of air ; on the contrary, with the distance
from the patient and the progressive dilution by
pure air there is evidently such a rapid diminution
of the chances of infection that they nre no longer suffi-
cient for a natural spread of the disease ; on the other
hand, where the transport is by the air the chances of
infection only exist in the immediate neighbourhood of
the sources of infection, and when the infective agents
pass over greater distances they are usually carried by
means of man or by surrounding objects.

The patient may therefore form the centre of a small
infectious area; from this new centres may then be
established in all possible directions, these centres having
their origin in infected patients, or in any other suitable
source of infection. The immediate neighbourhood of
such a centre is always specially dangerous ; whether,
however, a number of infections will occur in the same
house, or whether the danger will disappear there with-
out the occurrence of any new infection while infective
agents may possibly have been carried to other streets or
places, and give rise to fresh areas of infection, depends
in every individual case on a great variety of circum-
stances— on the number and resisting power of the sources
of infection, on the number of modes of transport, on
the individual susceptibility — and may vary to a great
extent. We must, therefore, after what has been said
in the foregoing chapters as to the multiplicity of all the
factors which come into play in infection, look on the
whole essence of distribution as something so dherse
and varying, and we must realise that the paths are so
tortuous and the results so unexpected, that we need not
be surprised either by a persistent localisation, or by an
apparently causeless leap of the disease over a consider-
able distance.

It is only where a community is overtaken by a new
and very contagious disease, where total ignorance of
the danger of infection renders every mode of transmis-
sion easier, and where every individual presents a predis-
posed body not yet protected by recovery from similar

MODE OF SPREAD OF INFECTIVE DISEASES. 763

affections, that there can be a general distribution of the
disease without distinction of person. In every other
case we meet with a great number of variations.

In the great majority of these variations it is unavoid- Laws as
able that we here and there come across apparent natural ie

laws ; one locality will be more frequently attacked than
another, one season of the year will cause an increase in
the number of cases of the disease, another will cause a
diminution, and so on. Such recurring local and sea-
sonal variations are in their essence only a further result
of the numerous concomitant accidents, and one cannot
from small numbers deduce laws which justify the
assumption of a special local or seasonal influence.

Here and there, however, the variations apparently
follow more distinct laws, and these point to external
influences, varying with place and season. This is a
priori intelligible if we consider in how marked a
degree the number and resisting power of the sources of
infection, the facility of transport, and the state of the
seats of invasion are dependent on causes varying with
place and time. Even in those diseases which are ex- In obligatory
tremely easily transmitted, <?.#., the acute exanthemata, pl
we can at times, though by no means always, recognise
regularly recurring seasonal or marked local variations.
Thus the statistics of small-pox epidemics show that the Seasonal
disease usually increases markedly in the cold months small-pox
and diminishes in summer ; and that, further, in warm ePldemic?-
climates there is a marked increase in the dry season, and
an almost complete disappearance in the wet months.*
One can scarcely go wrong in attributing the regular
increase of small-pox in winter to the greater amount of
time spent at home, to the more intimate association of
individuals, to the wearing of the same clothing for some
time, and to the diminished cleansing of the skin, thus
rendering the transport of the infective agents and their
preservation at the seats of invasion much easier than
in summer when all these favouring factors are absent.
These differences are of course more or less marked in
different countries, according to the climate and the

* Hirsch, Handbuch der histor. geogr. Path.. 2 Aufl., i., p. 105.

7()4 MODE OF SPREAD OF INFECTIVE DISEASES.

mode of life. In tropical climates the remarkable dimi-
nution of small-pox in the rainy season may be due to
the easier cleansing of the body and to the increased
difficulty in the transport of the infective agents by cur-
rents of air, perhaps also to certain habits of life which
cannot be thoroughly appreciated.

Local yaria- The mode of spread of scarlet fever forms a very
latinain *" striking example of the effect of locality. While epi-
epidemioB. demies of scarlet fever have constantly occurred in
Europe during the present century, and many of them
have spread from place to place, some towns have re-
mained entirely free from the disease for years, although
they have been in communication with the infected
places. Thus Minister has been free from scarlatina for
50 years, Tuttlingen for 35 years, and Ulm for 17 years,
while long intervals have occurred between the epidemics
in Lyons and also in the whole department of Indre-et-
Loire.* Experiences of this kind might very readily
mislead us into supposing that there was some special
influence, proceeding from the nature of the soil or from
some other part in the surroundings of man, which
favoured the development of scarlatinal epidemics in the
one case and hindered it in the other ; and yet we have
overwhelming proof that scarlet fever only spreads by
contagion. Nevertheless, in spite of the purely conta-
gious character of the disease, differences in its local
distribution may quite well occur. Thus it may happen
that all sorts of accidents, which can scarcely be gauged,
may prevent the infective agent, although repeatedly
introduced, from causing infection ; for example, these
agents may only come in contact with individuals which
have been previously attacked, and are therefore immune ;
or again, the infective agents may find a difficulty in
obtaining a foothold in these individuals, owing to their
cleanly habits, and so on. In a similar manner it is
possible that a particular city may present better oppor-
tunities for a long continued immunity than another,
in that the population may have been largely attacked
during a former epidemic, or in that the spread of the

* Hirseh, 1. c., p. 128.

MODE OF SPREAD OF INFECTIVE DISEASES. 765

disease from the first case may be rendered difficult on
account of certain habits of the population, such as
the mode of treatment of the sick (inunction of fat),
special attention to cleanliness, &c. — It is, however,
evident that even when a place has remained free
from the disease for several years, although repeated
epidemics have occurred in its neighbourhood, we are
not justified in asserting that this place possesses a
permanent immunity, due to a direct influence of the
nature of the place on the infective agents ; on the con-
trary, all these places have ultimately been found to be
susceptible as soon as the effect of the previous epidemic
has disappeared, and the chances against the attack of
the infective agents have become less favourable.

A priori we may, however, expect that these local and Greater local
seasonal variations will be more marked in the case of

those infective diseases which are not so extremely con- Jhe.less c°n-

v tagious

tagious as the acute exanthemata, but in which the diseases.
distribution is much more dependent on external acci-
dents. This will evidently be the case where the sources
of infection, the modes of transport, and the seats of
invasion are limited, and where a marked spread of the
infection can only result when there is a certain concur-
rence of these circumstances. The chief of these diseases In cholera.
are those which are occasioned by the contagious facul-
tative parasites, in which the number of the sources of
infection increases or diminishes under the influence of
external conditions, the modes of transport vary in their
value, and the seats of invasion become accessible or
inaccessible. The numerous influences which come into
play in these cases have been subjected to a more accu-
rate analysis in the chapter on cholera (page 443), and
from the description which has been given there we may
readily understand the manifold character of these influ-
ences and the applicability of the facts to other diseases
which show a similar mode of distribution.

In many towns a regularly recurring seasonal varia- in typhoid
tion is still more marked in the case of typhoid fever fever'
than in cholera ; thus during the dry harvest months,
and when the level of the ground water is low, the

766 MODE OF SPREAD OF INFECTIVE DISEASES.

number of cases of typhoid fever increases, while it
influence of a diminishes as the ground water rises. In explanation

drying zone of „ .. . . ,. . J ' , . ,

the soil on the ol tnis phenomenon the same iactors must be taken
typhokHever *n*° account as afforded to some extent an explanation
of the corresponding variation in the cholera epidemics,
but in the case of typhoid fever the drying of the super-
ficial layers of the soil at the time when the frequency
of typhoid fever increases comes more markedly into
play than in the case of cholera. As the typhoid bacilli
undoubtedly often reach the soil with the dejecta, either
when fresh or after being retained for some time in cess-
pools, and as they are present partly in the spore form,
and can thus be preserved for a long time and carried
by currents of air, the drying of the surface of the soil
or the sinking of the ground water must exert a much
greater influence on the spread of this disease than in
the case of cholera. The typhoid spores can, when a
dry zone is present, be very readily carried by currents
of air from the surface of the soil along with the dust
to dwellings and to various materials on which they
can develop, and thus the chances of infection are
much increased at these times.

It is true that there is no absolute necessity for
assuming an exclusive influence of the soil as an ex-
planation of the coincidence between the frequency of
typhoid fever and the dryness of the soil at the end of
Other factors. summer and during harvest. It is quite possible that,
as in the case of cholera, other factors which come more
markedly into play at these periods — such as the cha-
racter of the food, the large numbers of insects, factors
which influence the individual predisposition, &c. —
have an influence on the seasonal distribution of
typhoid epidemics. In those cities where there is a
constant and immediate connection between the dryness
of the soil and typhoid fever we can scarcely go wrong
in ascribing the sudden increase of cases chiefly to the
Their multi- drying of the surface of the soil. Where, however, the
seasonal relation is less marked, and where we have also
to explain a local distribution, we must not without very
strc ng reason refer the explanation only to alterations

MODE OF SPREAD OF INFECTIVE DISEASES. 767

in the soil ; on the contrary, the whole series of factors
which influence the local and seasonal occurrence, and
which have been referred to above, must be taken into
consideration just as much as in the case of those affec-
tions which are only contagious and which are in no
wise influenced by the soil, but which nevertheless also
show local and seasonal variations (scarlet fever, small-
pox). Among these factors the chief are certain habits
of life, selection and preparation of food, water supply,
cleanliness of the person and of the dwelling, and the
previous occurrence of epidemics with the consequent
immunity.

There are a number of factors which we can with Drinking
more or less certainty refer to as affording a certain
amount of explanation of the smaller epidemics
typhoid fever which often show a marked local and typhoid fever,
seasonal occurrence. At present there is a tendency
among physicians to find something remarkable and
only explicable by the assumption of a special and
specific mode of spread in almost all cases of typhoid
fever, whether they are limited to a single house, or
occur in neighbouring houses, or pass over streets ; the
usual explanation has been the presence of wells con-
taining so-called impure water.

It is no doubt quite true that the typhoid bacilli are
carried by the water in many large and in numerous
small epidemics, but it is equally certain that in a large
number of cases this mode of transport has been assumed
without sufficient justification. The view is also
generally held that it is only by means of the drinking
water that we can explain those cases where a small
circle of people become affected around the small central
epidemic, some of the persons in this circle being passed
over (these usually not having partaken of the water),
and where in addition a few individuals outside this
immediate circle become affected, these being shown
to have also consumed this water. On examining such
cases, however, we very often find that the statistical
facts were insufficient and incorrect, because they only
take into account a small portion of the population

768 MODE OF SPREAD OF INFECTIVE DISEASES.

Influence of
various
accidents on
the distribu-
tion of the
bacteria.

It is often im-

Sensible to
iscover the
caiise of the
local distribu'
tion of
epidemics.

surrounding the wells, and that the observer has paid
but little attention to this defect, on the assumption that
in no other way could such a peculiar distribution of
the disease have occurred.

To obtain an idea of the innumerable small accidents
which may influence the spread of the infective agents
in one or other direction, and that without the interven-
tion of drinking water, we only require to follow the fate
of a cultivation of some readily recognisable form of
bacterium, e.g., bacillus prodigiosus, when placed any-
where in a house. We can often observe how small
red colonies appear on various nutrient substrata and
articles of food, with regard to which it is evident, from
the place where they have developed or from the group-
ing of the colonies, that they have been carried by the
fingers, sleeves, table, or flies without intentional or even
conscious contact with the exposed cultivation. It
may further be observed that at one time the epidemic
is limited to the room in which the culture is ; at
another it suddenly appears in another and distant
room ; again it rapidly spreads over the whole house ;
or again it appears in neighbouring houses without any
affection of the immediate neighbourhood ; and lastly,
although the conditions are apparently the same, no
epidemic may occur. The result is so dependent in
each individual case on the most trivial accidents, that in
laboratories where much work is done with bacteria one
soon ceases to wonder at the peculiar and varying mode
of spread of this or that readily recognisable impurity.

Exactly analogous are the sources of infection of
typhoid epidemics, whether originating from a patient
suffering from the disease, or from infected earth, or
from spores which have been carried to suitable nutrient
substrata, or from any materials which have been con-
taminated with typhoid dejecta. The mode, the direc-
tion, and the extent of the spread of the epidemic from
these sources depends on a great variety of accidents.
As in the case of the prodigiosus cultivation, the trans-
port by man and various objects will play a very
important rule ; the result in each case will, however,

MODE OF SPREAD OF INFECTIVE DISEASES. 769

depend on whether the germs can live in the place to
which they are transported, whether they find sufficient
nutrient materials to permit their growth, &c.

Thus it is only seldom that we are able to pick out
the true mode of transport from the many possible ones.
This want of knowledge, and our open acknowledgment
of it, does not, however, render it more difficult to take
prophylactic measures against a typhoid epidemic. In
whatever way the spores have been transported they are
in all probability introduced into the body by water and
food ; and they only leave the body by the dejecta. If
the latter are thoroughly disinfected or removed by a
good system of drainage, if the water is taken from
proper wells, and if the selection and preparation of
food is attended to, a typhoid epidemic can be satis-
factorily coped with even though the exact mode of
transport in each individual case remains unknown.
The closure of suspected wells is also a perfectly proper
procedure, though the reason for doing so is not now
the same as formerly; the former practice led to in-
sufficient and probably erroneous views as to the etio-
logical importance of the water, and to too great one-
sidedness in the prophylactic measures.

It is evident that the great multiplicity of the factors
which play a part in the local and seasonal distribution
of all infective diseases makes it extremely difficult to
draw conclusions as to the nature and the infective
properties of the causal agents from these local and
seasonal variations and from the laws which appear to
govern them. At the present time, when we can study Difficulties in
the behaviour of the infective agents themselves, and eddmAtiDgtte
can solve the question of their mode of distribution local and
experimentally, it would help us but little to employ the disposition'0"
former circuitous method by which we drew conclusions
as to the characters of the infective agents from the
phenomena of their local and seasonal distribution; it
is much better to attempt to gain a solid basis from
experiments with the isolated infective agents them-
selves, and thus to obtain an explanation of the results
of epidemiological statistics.

49

770 MODE OF SPREAD OF INFECTIVE DISEASES.

Prophylaxis
by influencii
the individu
predisposi-
tion.

Prophylaxis
by destruction
or removal of
the infective
agents.

General pro-
phylactic
measures.

7. The most Important Prophylactic Measures against
the Spread of the Infective Diseases.

We can very easily deduce the prophylactic measures
against infective diseases from the facts as to the mode
of spread of these diseases which have been referred to
in the foregoing paragraphs.

In some cases it seems hest to direct our precautionary
[ methods rather towards the individual predisposition of
the body than towards 'the infective agents, and in fact
to neglect the latter more or less completely. The most
marked example of this is tuberculosis (see p. 752).
It is possible also that other infective diseases will be
best held in check by such a method of prophylaxis, and
probably there is a great field for investigation and for
practical work in this direction.

Among the means of lessening the individual pre-
disposition we have also protective vaccination, the
practical value of which — with the single exception of
vaccination for small-pox — must, however, for the
reasons given above (p. 760), be judged on the whole
unfavourably.

In the great majority of cases, however, our prophy-
lactic measures deal with the infective agents themselves,
and seek to destroy them, or to hinder their development
or spread.

The reporting of cases, quarantine, and the isolation
of the sick are precautions which do not require any
special discussion, nor do the points which would have
to be discussed in connection with them specially con-
cern the matter of this work, and we may therefore pass
them over. We have here to do with the measures for
the destruction and removal of the sources of infection
mentioned on p. 736, and for interfering with the modes
of transport (see p. 739). The following are the most
important precautions in this direction : —

a. Measures which are generally applicable. — In cases
of disease it is of the first importance to destroy or disin-
fect all the excreta of the sick which may contain the effec-
tive ugcnts, and all the objects contaminated with them,

MODE OF SPREAD OP INFECTIVE DISEASES. 771

more especially linen, beds, &c. ; it is further necessary
to keep all these sources of infection in a moist state
till they can he disinfected, so that the infective
agents may not become detached and carried away by
currents of air. (This is unnecessary in cholera.) All
surrounding objects which might retain the infective
agents, and which are difficult to cleanse, should be re-
moved as far as possible, and protected from con-
tamination (for example, soil, &c., the doors and walls
of sick-rooms should be closely covered with some im-
permeable material). Those who come in contact with
the sick should be particularly cleanly, and should also
wash with sublimate or carbolic lotions ; similar cleanli-
ness is also necessary with regard to the clothing, the
dwelling, the kitchen, &c. It is also desirable that those
who are particularly predisposed to one or other disease
on account of the presence of abnormal points of invasion
(as in the case of wounds, catarrhs, gastric disturb-
ances, &c.) should avoid the danger of infection, and
should observe the necessary precautions even when no
evident sources of infection are present.

b. Special precautions in individual diseases. — In special pre-
the case of the acute exanthemata we must attempt by ^diridaar
rubbing oil over the skin of the patient to prevent, or at diseases,
any rate to limit, the detachment of the infective agents
from the surface of the body, and their transport through
the air. Thorough ventilation of the sick-room, which
is much recommended for prophylactic purposes, can, it
is true, lead to a dilution of the germs, but it is difficult
even by the best methods of ventilation to diminish the
chances of infection to such an extent as occurs in the
open air, and as is requisite if we are to place ventila-
tion on the same footing as the other prophylactic
measures.

In those diseases in which the seat of invasion and
the seat of the disease lie in the intestinal tract, such as
cholera and typhoid fever, we must, when there is a great
danger of infection, pay the greatest attention to the
preparation of the food, and we must also see that the
drinking water comes from pipes or from good wells,

772

MODE OF SPREAD OF INFECTIVE DISEASES.

Disinfection.

Disinfection
of excreta.

Disinfection
of linen, beds,
&c.

Apparatus for
disinfecting
by means of a
current of
fcteam.

and this is clone by insisting that all food must be
cooked, and that all water must be filtered through a
proper apparatus. Where sources of infection are pre-
sent we must also employ the general precautions
referred to above. An extremely important measure
consists in making arrangements to remove dejecta and
waste water rapidly and to get rid of gutters, and thus
to render it impossible for the surface of the surrounding
soil, the wells, and the watercourses to become con-
taminated with dejecta.

The prevention of fresh sources of infection by means
of a rational method of disinfection, forms the most im-
portant part of the prophylactic measures in the majority
of the infective diseases. This method applies to the
following materials, and is carried out by the- following
means :—

1. The infective excreta of the patient (sputa, dejecta,
pus, &c.) should be mixed with 5 per cent, carbolic
acid (or if necessary with commercial fuming hydro-
chloric acid), and allowed to stand for twenty-four hours,
each motion being disinfected at once. The receptacles
must be repeatedly washed with similar solutions. In-
fective material on the body of the patient must also be
removed by means of carbolic acid, or sublimate solu-
tions.

2. The linen and bed linen of the patient, dressings,
feather beds, woollen blankets, mattresses, straw beds,*
handkerchiefs, curtains, carpets, &c., should be dis-
infected by a current of steam at 100° C. Various
apparatuses have been constructed in recent years for
carrying out this method of disinfection, and of these
three have been tested and found satisfactory. These
are the apparatus made by Schimmel & Co. in Chem-
nitz, the stationary and portable apparatuses made by J.
L. Bacon in Berlin, and lastly that by Eietschel &
Henneberg. — So far as possible these various machines

* It is usually beat to burn straw beds and other worthless materials.
In practice, however, this cannot always be done without risk of
infection, and in that case it is simplest to disinfect these mateuials
also in the steam apparatus.

MODE OF SPREAD OF INFECTIVE DISEASES. 773

should be round, or nearly round, in order to avoid the
presence of corners in which the disinfection may very
readily he imperfect. It must also he home in mind
that hot air containing a certain amount of steam does
not by any means have the same effect as a good
current of steam without any air (see p. 665) ; those
forms of apparatus are untrustworthy in which steam is
present even under high pressure, hut not in such
quantity that after filling the apparatus a good current of
steam escapes from it. It does not seem to be necessary
to raise the temperature of the steam by employing
saline solutions ; it has been definitely proved by
numerous experiments in Koch's laboratory, and by
comparative tests by Wolff which were made on a num-
ber of machines and in a trustworthy manner, that even
very large objects (balls composed of 22 woollen blankets)
are completely disinfected by exposure for one to two
hours to a current of steam at 100° C. One hour
suffices for smaller objects, and half an hour for linen
and clothing, the time being reckoned from the moment
when the steam which escapes shows a temperature of
100° C.

By this plan the injury done to the materials is very
slight. Linen, feather beds, mattresses, clothing,
printed matter, &c., are quite unhurt, but sensitive
colours are somewhat altered. Disinfection by heat
cannot be employed for objects made of leather (boots),
gum, or caoutchouc, and bound books.

No definite statement can be made as to the special
advantages of one or other of the disinfecting appara-
tuses mentioned above ; at all events, they are all trust-
worthy and useful. They are prepared in various sizes
and at various prices, and one ought to be in use in every
town.

In Gottingen a very simple and cheap apparatus has heen Special

introduced provisionally, and acts extremely well. It is con- f^jj^f*1™ °f
structed on the same principles as the sterilising apparatus ratus for dis-
commonly used in laboratories and described on page 665, infection.
being merely correspondingly larger. It is desirable to have
two of these machines of different sizes, the one being 7
metres in height and 50 cm. in diameter, the other 1'4 metres

774 MODE OF SPKEAD OF INFECTIVE DISEASES.

Method of
heating.

Construction high and 80 cm. wide. The smaller, which costs with acces-
sory apparatus about £7 10s., is employed when portions of
clothing or linen are to be disinfected (as in tuberculosis) ;
the larger, which costs about £13, serves for the disinfection
of beds, mattresses, &c. — The apparatus is made of tin, with
the exception of the bottom, which is copper, and has a conical
shape, enlarging at the lower part so as to increase the
heating surface. The receptacle for the water is provided
with a tube projecting outwards, through which it is filled,
with a pressure gauge tube, and with a stop cock to empty it.
To provide air-tight fittings for the lid, and also at the
attachment of the body of the machine to the boiler, these
parts fit into grooves which are filled with water. To prevent
cooling, the body and the lid are protected by a thick layer of
clay, which is fixed on by means of gauge bandages, and an
external arrangement of wire netting. In the lid there is a
tube for a thermometer, and another for the steam, with
which a long leaden tube is connected so as to conduct the
steam out of the house.

The apparatus is heated by gas. In the case of the larger
apparatus twelve large Bunsen burners are necessary to raise
the temperature of the thermometer in the lid to 100° C. within
half an hour ; for the smaller apparatus five burners are
sufficient. This method of heating has the advantage that it
can be very cheaply fitted up, that the temperature remains
constant, that the heat is very completely utilised, and that
the disinfection is completed in a very short time (within
two hours). The cost of the gas for the larger apparatus is
about sixpence per hour, that for the smaller about 2|d.
Where larger machines are employed boilers and fires are of
course indispensable.

Attempts have been made to add arrangements to warm
the clothing, &c., previously, and to pass a current of dry
hot air through them subsequently to the disinfection in
order to dry them as quickly as possible. These arrange-
ments have not, however, acted well, and they lengthen the
Prevention of process too much ; they are besides quite superfluous if care
wetting^of the js taken to prevent the materials from coming in contact
with the water. If the materials are only moistened by the
current of steam they dry in a very short time, within half
an hour ; and it is only at those places where the water has
soaked in that the moisture remains longer and that the
colours are more readily destroyed. Hence in the apparatus
described above special care has been taken that the water
condensing on the walls or top of the apparatus shall not run
on to the materials which are being disinfected. Beds and
similar bodies are placed in a cylindrical basket of strong

materials.

MODE OF SPREAD OF INFECTIVE DISEASES. 775

wire, the sides of which are at least 1 cm. from the wall of the
vessel, and are lined with wire netting and inside that with
waxed cloth, which is the only material impermeable to water
which stands heating well. Further, to protect the articles
from water dropping from above without preventing the
passage of the steam they are covered with several layers of
cloth. By means of these simple arrangements the articles
can be dried in half an hour if they are laid out on a dry
frame arranged around an ordinary iron stove, and thus only
two to three hours elapse from the beginning to the end of
disinfection. — Above the apparatus an arrangement is fixed
by means of which the cover can be raised and turned aside,
the basket introduced or removed, and the cover replaced in
u very few minutes.

Spring mattresses can be sufficiently disinfected by
scrubbing them with sublimate solution (1 : 2000) ; it is
most convenient to combine this procedure with the dis-
infection of tbe dwelling. Boots, indiarubber materials,
<fcc., sbould also be washed with sublimate solution.

3. In the house, the bedstead (and the other furni- ^fist£efection
ture if necessary) and the floor should be scrubbed with dwelling,
sublimate solution, and afterwards washed with soap and
water. In the water-closets, the seat, the pan, and the
drain should be scrubbed or sluiced with 5 per cent,
carbolic lotion. The contents of cesspools, &c., should
be mixed with commercial hydrochloride acid till the
reaction of the contents after being well stirred is
markedly acid. Where the cesspools are very large we
cannot attempt disinfection. — As to the defects and the
methods of disinfection of the air see p. 669. In most
cases no attempt is made to disinfect the air, but reliance
is placed in thorough ventilation. We may, however,
before disinfecting the floor, furniture, &c., attempt
to cause deposition and fixation of the air germs by
loading the air with moisture by means of steam or spray.

To carry out thorough disinfection it is essential that Necessity for
there should be a staff of educated persons, indeed this
is quite as necessary as the possession of a proper ap-
paratus. In a small town three trustworthy persons
are sufficient ; these should be thoroughly instructed
and examined by the medical officer ; in larger cities the
staff must be correspondingly more numerous.

776 MODE OF SPREAD OF INFECTIVE DISEASES.

Regulations
for disinfec-
tion in
Gottingen.

In Gottingen the following regulations have been drawn up
by Dr. Schiitte.- — Families in which a case of infective disease
has occurred, and who desire disinfection, must send an
intimation to the court-house, stating also the nature of the-
disease. In this way the staif can judge as to the extent of
the disinfection and the method to be employed ; the follow-
ing are their instructions according to the nature of the
case : —

Small-pox, scarlet fever, typhus fever, diphtheria, &c. ;
linen, beds, curtains, £c., are to be disinfected with a current
of steam ; bedsteads and floors to be scrubbed with sublimate
solution; upholstery, &c., to be moistened with sponges
dipped in sublimate solution, and at once dried.

Cholera, typhoid fever, dysentery: disinfection of linen,
&c., by steam. Water-closets disinfected with 5 per cent,
carbolic acid; cesspools, &c. with commercial hydrochloric
acid. In cholera warm and ventilate the room, in typhoid
fever and dysentery cleanse the bedsteads, floor, &c., with
sublimate solution.

Tuberculosis : disinfection of the linen and beds.

The persons who are to carry out the disinfection take
with them all the solutions, vessels, brushes, &c., also some
iiidiarubber garments, and a number of moistened cloths of
various sizes ; also the wire basket from the sterilising
apparatus. These are transported in a suitable hand barrow.
When they reach the house they put on the iiidiarubber gar-
ments, and take the utensils and cloths into the room, wrap
the beds, mattrasses, clothes, &c., in the moist cloths, cleanse
their hands and mackintoshes with sublimate solution, and
place the parcels in the wire cage. One of the disiiifectors.
takes these back to the apparatus, which has been in the
meantime heated by the third, while the first remains behind
and disinfects the room. After two to three hours the beds,,
&c., are brought back, and in the meantime the room has
been disinfected.

The detailed instructions may be obtained from the magis-
trate of Gottingen, or from Dr. Schiitte, the medical officer of
health.

It is a fact which cannot be overlooked that it is as a
result of the recent bacteriological investigations that,
we are in a position to employ trustworthy prophylactic
measures against the infective diseases, and more
especially to carry out the disinfection so thoroughly
that it has become one of the most potent means of
opposing the spread of these affections.

777

PAKT VIII.

METHODS OF INVESTIGATING BACTERIA.

I do not propose in the present work to give at all a
complete description of the various methods of bacterio-
logical investigation ; such an attempt would very much
increase its size, and is so much the less necessary as
very thorough descriptions of bacteriological methods
have been given by Hueppe, and also in a recent work by
Huber and Becker (Leipzig, Vogel, 1886).

In the following pages I shall only put together the
most important methods for the microscopical examina-
tion of bacteria, for their cultivation, and for their
demonstration in air, water, and soil.

I. Microscopical Examination of the Lower Fungi.

We can examine microscopically a great variety of Methods of
materials, such as fluid and solid substances, nutritive ^a^S?™
materials, dust, earth, animal and vegetable organs and of bactena-
juices, fungus colonies, &c. In doing this we must
always remember that these lowly organisms are con-
stantly present in all our surroundings, and that in order
to demonstrate the presence of the fungi in any one of
these materials care must be taken to prevent the
accidental introduction of fungi into the preparation
from the surroundings. All instruments, glasses, re- Apparatus,
agents, &c., must therefore be free from organisms, and
this is best attained in the case of the instruments and
glasses by exposing them for a short time to a tempera-
ture of at least 150° C., or, still better in many cases, by
placing them in a solution of corrosive sublimate 1 to
2,000.

778

METHODS OF INVESTIGATING BACTERIA.

Mode of
specimens.

staining of

bacteria.

Cover glass
preparations.

If we are investigating pathogenic organisms we must
remember that numerous fungi are constantly growing
on the surface of healthy living animals, on the skin, in
the cavity of the mouth, &c. After death these organ-
isms rapidly spread, in the first place, into all the
superficial parts of the body; specimens taken with the
view of investigating the presence of pathogenic organ-
isms must therefore never be taken from the impure
surface, even in the case of living animals ; and after
death we must always try, if possible, to obtain the
specimens from the interior of the organs by making a
series of fresh cuts with a heated knife.

The direct microscopical observation (sometimes after
the addition of a half per cent, soda solution, a mixture
of glycerine and water, or a solution of acetate of potash
1 to 10) without further aids only gives results at all
satisfactory in the case of the larger fungi, or of cultiva-
tions of bacteria ; if other objects, such as cells, nuclei,
or fragments of nuclei, crystals, and amorphous in-
organic materials, are present in the preparation we
may not be able to recognise the bacteria, even under
very high powers of the microscope. Hence in almost
all cases where it is important to examine the preparation
accurately it becomes necessary to stain the micro-
organisms. The bacteria take up certain colouring

. , . , * -

materials with extraordinary energy, and we can usually
so manage the staining that the micro-organisms alone-
are coloured, or at least these alone are markedly
stained, while all the other objects in the preparation
are but faintly, or not at all, tinged. And where we
wish to demonstrate the absence of micro-organisms
from some material it is only possible to do so with any
degree of certainty by the aid of methods of staining. —
The treatment of the preparations with the view of
staining them differs according as we have to do with
fluids or with animal organs.

Fluids are in the first place dried on a cover glass in
a yer^ ^^ iayerj a sman drop being placed on the
glass by means of a recently heated platinum wire, and
spread out over it by a few circular movements, or still

METHODS OF INVESTIGATING BACTEBIA. 779

better "by laying a second coyer glass on the top of the
first, so that the drop is spread out, and the layer of
fluid extends to the border of the cover glass ; these
glasses are then slid asunder, and thus we obtain two
thinly-spread layers ; these layers dry in a few minutes.
If now the cover glass is at once brought into con-
tact with the staining solution the layer again becomes
detached, and is washed away; hence the organisms
must first be fixed on the glass as far as possible.
This can be done either by prolonged immersion of the
glasses in absolute alcohol, or by exposing them for a
short time to a temperature of from 110° to 130° C.
(for two to ten minutes), but the exact degree of heat
differs somewhat in the case of different objects, and
must be ascertained by experiment. This heating can
be conveniently and sufficiently done by passing the
cover glass two or three times slowly (" about as quickly
as we cut bread ") through the flame of a Bunsen burner
or a spirit lamp. After this treatment the organisms
adhere so firmly to the glasses that these can be kept
for a long time in watery fluids without any bad result.

The cover glass being prepared in this way a drop of
one of the staining solutions mentioned below is placed on
it ; it usually suffices to allow the solution to act for from
fifteen to twenty minutes ; if we wish to prolong the action
it is advisable to float the cover glasses on the staining
material contained in a flat vessel. The cover glass is
then seized with forceps, freed from the stain by filter
paper, washed in distilled water, or at times in very
dilute acetic acid (5 to 10 drops to 100 com. of water),
and then placed on the slide with a drop of water, or
else dried and mounted in oil of cloves or Canada
balsam.

Organs must in the first instance be hardened in Treatment of
absolute alcohol for some time (several days) ; in doing sec
this plenty of alcohol must be used, and it is well to cut
the organs into small pieces. A number of fine sections
are then made, if possible by means of a microtome, and
are placed in the first instance in absolute alcohol, and
from thence transferred to the staining solution. The

780 METHODS OF INVESTIGATING BACTERIA.

sections remain in this solution for from a half to five
hours, in some cases even for twenty-four hours. By
warming the solution to 30° to 40° C. the duration
of the staining can he considerably shortened. When
the sections are taken out of the stain the whole tissue is
strongly coloured, and hence we must attempt to produce
a differentiation between the organisms and the tissue by
placing the sections in alcohol, or in dilute acetic acid,
which has the effect of withdrawing the colouring matter
from the cells, and leaving only the organisms and at
most the nuclei of the cells stained (in addition also
certain forms of mucine, horny tissue, at times fat, and
the axis cylinder of nerves retain the stain). In most
cases the best method of decolourising tissue is to leave
the sections in alcohol for fifteen to thirty minutes,
then to transfer them to oil of cloves, from this again
to pure alcohol, and then again to oil of cloves. It is
well at times to employ dilute acetic acid before the
alcohol. The sections can be at once examined in the
oil of cloves ; or they can be transferred to slides, the
oil removed carefully by blotting paper, and the sections
then mounted in balsam. Some colouring matters are
dissolved out by the oil of cloves, and in these cases the
sections are transferred from alcohol to oil of bergamot
or xylol, in some cases after a previous short immersion
in oil of cloves. — If we have a freezing microtome at
hand the fresh organ can be at once frozen and cut.
The sections are then in the first instance placed in salt
solution, from which they are carefully removed to abso-
lute alcohol, and then treated as above described.
Staining Carmine or haematoxylin are only rarely employed as

staining materials, the chief dyes used being the aniline
colours, to which the lower fungi show a great affinity.

According to Ehrlich* we have to distinguish two
great groups of aniline dyes which are sharply defined
from each other by their chemical and histological
peculiarities ; these are the acid and the basic colouring
materials.

* Westphal, Schwarze, Spilling (Lit.), Weigert.— See also Virchow's
Arch., vol. 84.

METHODS OF INVESTIGATING BACTEKIA. 781

Among the acid dyes we reckon all those colouring matters
in which the staining substance is an acid ; the dye is not
necessarily, however, a free acid, nor need it even have an
acid reaction, it may be in combination with bases forming
salts, such as picrate of ammonia. There are four classes of
acid colouring materials, viz. : 1. Fluorescine ; to this group
belong fluorescin, pyrosin, eosin (tetrabromfluorescin), and
several others. 2. Nitro bodies — for example, Martin's yellow
(a salt of binitronaphthol), picric acid, aurantia (the ammonia
salt of hexanitrodiphenylamine). 3. Sulpho acids — for ex-
ample, tropaeolin, bordeaux, ponceau ; derivatives of the form
of aniline blue which is soluble in spirit ; aniline black, &c.
4. Primary acid dyes — for example, rosolic acid, alizarine,
nitroalizarine, purpurine, coeruleine, possibly ha3matoxyline,
&c.

To the basic dyes belong fuchsine (rosaniline), methyl
violet, methyl green (both of them methyl derivatives of
rosaniline, the latter being usually contaminated with methyl
violet), triphenylrosaniline (impure aniline blue) and its
derivatives, cyanine, safranine, magdala ; further, the stains
which are more especially employed for colouring bacteria,
viz., Bismarck brown, dahlia, and gentian violet.

The basic colouring matters are not usually sold as free
bases, but as salts ; thus fuchsine is sold as hydrochlorate or
acetate of rosaniline.

The basic aniline dyes are almost alone suitable for
staining bacteria ; they, however, also stain the nuclei.
In order to prevent the occurrence of a diffuse stain of
the whole tissue we must treat the stained preparations
with solutions which have a greater affinity with the
staining material than the tissue, hut less affinity than
the micro-organisms (and nuclei of cells) ; such solutions
are alcohol and dilute acetic acid.

Many bacteria only take up few stains well ; and hence
in searching for unknown micro-organisms all the various
staining materials must he employed with or without the
addition of acetic acid, or in faintly alkaline solution ;
the spores of bacilli do not take up the colouring matter
unless when they are specially treated. In the case of
most forms of micrococci all the nuclear stains (carmine,
hsematoxyline, basic aniline dyes) are suitable. These
organisms can he stained red with the various forms of
carmine which stain the nuclei, and also with purpurine,

782 METHODS OF INVESTIGATING BACTERIA.

fuchsine, magdala, and magenta ; brown, with Bismarck
brown, or vesuvine ; green, with methyl green ; blue or
violet, with hsematoxyline, methylene blue, iodine violet,
methyl violet, dahlia, and gentian violet. Many of the
bacilli, however, can only be stained by those aniline
dyes which stain nuclei. The following are the materials
which are most used.

Most useful Methylene blue, more especially in faintly alkaline
tions!ng " solution (Loeffler's universal staining fluid). This fluid
is prepared by mixing 1 ccm. of concentrated alcoholic
solution of methylene blue, which can be kept for a long
time, with 200 ccm. of distilled water, and then adding
two to four drops of a 10 per cent, solution of caustic
potash. The mixture must be refiltered every day, and
must be freshly prepared about every eight days.

Gentian violet (B.R. in the catalogue of the Berlin
company for the manufacture of aniline dyes) in about
1 per cent, watery solution.

Fuchsine is kept at hand in the form of a concentrated
alcoholic solution, and is diluted with about five times
the amount of water when required.

Methyl violet, gentian violet, and dahlia show in a
special degree the property of metachromatic staining,
i.e., they stain various elements of a shade somewhat
different from the primary colour, reddish to red, &c.
Methyl green, which is usually contaminated with methyl
violet, often gives blue, and at times rose tints.
Double stain- In order to differentiate better between nuclei and
bacteria double staining is at times very suitable; we
may mention, for example, double staining with picro-
carmine and gentian violet, wrhich depends on the fact
that the carmine can drive out the violet from the nuclei,
but not from the bacilli. The sections are placed in the
first instance in a solution of gentian violet, then in
alcohol, then for a moment in water in order to remove
the alcohol, and then in Weigert's picro-carmine solu-
tion. After remaining in this solution for a half to one
hour they are passed through water, alcohol, oil of
cloves, and Canada balsam. The result is that the
nuclei of the cells have a red colour, while the bacilli

METHODS OF INVESTIGATING BACTERIA. 783

are stained blue. The clubs of actinomyces can be
stained reddish-blue by treatment first with Wedl's
orseille (Yirchow's Archiv, vol. 74), and then with
gentian violet.

Tubercle bacilli are best stained by the following To stain
method (see p. 261): aniline oil and water are well
shaken up together, and then filtered through moistened
thick filter paper ; concentrated alcoholic fuchsine or
gentian violet solutions are then cautiously dropped into
the filtered aniline water till a slight cloudiness is noted,
which later again disappears (about 10 to 20 drops of
the stain to 10 ccm. of aniline water). The cover glasses,
prepared with sputum in the manner above-mentioned,
are then floated on this colouring material for from twelve
to twenty- four hours, or, if the solution is kept at a tem-
perature of 30° to 35° C., for one to two hours ; in the case
of sections, it is best to stain them for twenty-four hours,
and then to warm the solution for one to two hours. The
cover glasses and sections are then washed in the first
instance in acidulated alcohol (100 ccm. alcohol, 20 ccm.
water, and 20 drops of concentrated hydrochloric acid) ;
after a short time (a half to two minutes) the red or violet
colour is removed from all the thinner parts of the pre-
parations, which are now carefully washed in water, the
cover glasses dried, and then stained in dilute watery solu-
tion of methylene blue if fuchsine has been employed in
the first instance, or with a solution of vesuvine if gentian
violet has been used. After five to fifteen minutes
they are washed in water, dried, and mounted in Canada
balsam. Sections are placed for half an hour in the
methylene blue or vesuvine solution, and then treated in
the usual manner; if the preparations are to be preserved
we must employ oil of bergamot instead of oil of cloves. —
In this way we obtain preparations in which the tubercle
bacilli are stained red or violet, and the cells and cell
nuclei blue or brown. The only other organisms which
show the same staining reactions as tubercle bacilli are,
so far as we know at present, the leprosy bacilli. Some
other materials also retain the stain in this method, such
as the epidemic structures, the spores of the mould fungi,

784 METHODS OF INVESTIGATING BACTERIA.

the spores of bacilli under certain conditions, and also
at times fat crystals, which are sometimes present in
sputum; the fat crystals are, however, readily soluble
in ether and chloroform (Celli and Guarneri). — The pure
solutions of the dyes, and also the mixture of aniline
and water, can be kept for a long time, but the latter
must always be freshly filtered before use, and the mix-
ture with the colouring material must always be freshly
prepared. — The following solution will, however, keep for
from ten to twelve days : 100 com. saturated aniline water,
+ 11 ccm. concentrated alcoholic solution of methyl violet
or fuchsine, +10 ccm. absolute alcohol. — With regard
to the numerous other methods of staining bacteria, see
the papers by Plaut* and Kaatzer.f

As regards the staining of the bacilli of syphilis and
smegma, see p. 289.

Gram's Gram's method is admirably adapted for the differential

staining of bacteria in the tissue, and also as a means
for the diagnostic separation of many species of bacteria.
It consists of, 1, aniline gentian violet solution, Ehrlich's
formula (as for staining tubercle bacilli) ; 2, solution of
iodine and iodide of potassium, composed of 2 grammes
of iodide of potassium, 300 grammes of water, and 1
gramme of iodine. The sections are transferred from
absolute alcohol to the staining solution, and remain
there for from one to three minutes (in the case of tubercle
bacilli for twelve to twenty-four hours) , then after a short
immersion in alcohol they are placed in the iodine solution.
After one to three minutes the sections are again placed in
alcohol till they are completely decolourised, then in oil of
cloves, &c. As a result the tissue and nuclei have a
faint yellow colour; the bacteria, on the other hand, are
intensely blue or black. Cover glass preparations are
treated in a similar manner. — The following organisms
retain the stain in this method: the bacteria of pneu-
monia, the cocci of pyaemia and erysipelas, staphylococci,
tubercle bacilli, anthrax bacilli, and various saprophytes;

* Plaut, Fdrbungsmethoden u. s. w., 2 Aufl., 1885.
t Kaatzer, Die technik der Sputumuntersuchung auf Tuberkelbacillen
2 Anfl., 1885.

METHODS OP INVESTIGATING BACTERIA. 785

on the other hand, typhoid hacilli and cholera spirilla are
decolourised by the iodine solution.

Buchner,* and subsequently Hueppe, was the first staining of

, „ , . . . . ,, f . the spores of

who was successful in staining the spores of various bacilli,
bacilli. In order to stain the spores the cover glass
preparations are raised to a higher temperature than in
staining the bacteria, thus they are not passed three times
but from six to ten times through the flame, or they are
kept for a quarter to half an hour in a dry chamber at a tem-
perature of 180° to 200° C. After this treatment the spores
take up the ordinary aniline dyes. — Neisser, however, suc-
ceeded in staining spores by the use of the solutions
employed to stain tubercle bacilli when they were at the
same time warmed. Cover glass preparations, prepared
in the ordinary manner, are floated on the aniline fuchsine
solution at a temperature of 80° to 90° C. for ten, twenty,
or even forty minutes, and are subsequently treated like
preparations of tubercle bacilli. By this method the
spores are stained red and the bacilli blue.

In order to preserve the preparations we can employ Preservation
Canada balsam, dammar, a concentrated solution of £aration.e~
acetate of potash or glycerine ; the latter, however, is
only suitable for preparations stained with solutions of
aniline brown which contain glycerine. — The best mount-
ing material for mould and yeast fungi is glycerine gela-
tine (one part of gelatine, six parts of water, seven parts
of glycerine, and one part of carbolic acid, warmed and
filtered).

For the examination of the preparations only the best Microscopical

.,17 T ,-, f .-, , investigation.

microscopes are suitable. In the case of the larger
forms of bacteria — for example, anthrax bacilli — dry
lenses are sufficient, in the case of all the smaller forms
it is necessary to use the best oil immersion lenses. t
In order to be able to recognise the stained bacteria in
the tissue a special mode of illumination is necessary.

* Miinchener cirzll. Intelligenzbl., 1884, p. 370.

t Excellent oil immersion lenses and apparatus for illumination are
furnished by Zeiss of Jena, Seibert and Kraft, Leitz and R. Winkel
in Gottingen. Winkel's lenses are excellent, and, according to the
author's experience, are most worth the money. — Colouring materials
and other apparatus can be obtained from Dr. Griibler in Leipzig.

50

786 METHODS OF INVESTIGATING BACTERIA.

It would of course be best if we could obtain a pure
colour picture, i.e., if the Canada balsam and the tissue
had an identical refractive index, and as a consequence
the tissue were not at all visible, and only the bacteria
could be seen by virtue of the stain that is, in them.
But usually the various portions of the tissue have a
different refractive index to the Canada balsam, and give
rise by diffraction of the transmitted rays of light to the
structure picture, which consists of lines and shadows,
and which obscures the colour picture. We must there-
fore try, as far as possible, to obliterate these diffraction
appearances and the structure picture, and this can be
done by the employment of a suitable illumination appa-
ratus.

Abbe's sub- If we examine a microscopical preparation illuminated at

stage con- first with a narrow, and then with a constantly but slowly
increasing cone of light, we find that the diffraction appear-
ances and the structure picture, which were most intense
with the narrow diaphragm, gradually disappear ; and to the
same degree as the structure picture diminishes, so the colour
picture becomes more intense and sharper. Hence where
possible a condenser must be employed with so large an angle
that the diffraction appearances are completely obliterated.
An instrument which attains this object completely is the
condenser devised by Abbe, and prepared by Zeiss. This
consists of a combination of lenses, the focal point of which
is only a few millimetres distant from the front lens. When
this lens is placed in the opening of the stage of the micro-
scope at a somewhat lower level than that of the stage the
focal point falls on the object under examination, and the
latter is consequently best illuminated in this position. The
angle of aperture of the rays is so great that the most external
of them are bent in a layer of water almost 16° towards the
axis, and hence the total active cone has an aperture of 120°,
a broader aperture than that of any other condenser. The
rays of light are sent into the system of lenses by means of a
mirror which can only rotate around a fixed point in the axis
of the microscope. Between the mirror and the lens, and
near the focal point of the former, we have the arrangement
for diaphragms which can be moved laterally and circularly,
so that the cone of rays may be altered in any manner
desired. By means of a greater or less diaphragm the
aperture of the lens is modified from the smallest to the
largest.

METHODS OF INVESTIGATING BACTERIA. 787

The appearances observed under the microscope are Photography
best reproduced by means of photography. The cover of bactena>
glass preparations prepared in the manner above de-
scribed permit the employment of high power immersion
lenses. It is best to stain the organisms brown.
Photography also possesses a special advantage in that
the photographic plate reproduces the microscopic
picture better, or rather with greater accuracy, than does
the retina of the eye.

The sensitive plate is to a certain extent an eye which is
not blinded by bright light, and which does not become tired
by the attempt to distinguish between minute differences in
light, &c. We often find 011 the negative, when the picture
has been sharply focussed, fine objects, for example, minute
nagella, which can only be seen with the greatest difficulty,
and under the most favourable conditions of illumination.

As regards the methods of photography see the works
mentioned below.*

Bacteria, more especially micrococci, may be con- Differential
founded with detritus, but the latter shows granules
irregular size and grouping ; we also at times find small
drops or little spheres, which become stained with the
dyes, and the nature of which is as yet doubtful. Con-
fusion is most likely to occur with the cells described by
Ehrlich under the name of " Mastzellen " (plasma cells,
granular cells), which are very widely distributed, and
increase in number in various pathological processes.
The uniform round granules of these cells are usually
stained in a similar manner, and with a similar shade,
to the bacteria ; and the two forms can often be only
distinguished by the position which they occupy, and
more especially by the fact that the granules in the
plasma cells are always grouped in the form of cell-like
structures. If it is necessary to make certain that we
are studying bacteria the following method may be
employed : after staining with aniline the sections are

* Gerlach, Die Photographic als H&lftmittel mikroskoplscher Forschung
Leipzig, 1863.— Beneke, Die P hoi oy rap hie als Hillfsmittel u. s. w., Braun-
chweig, 1868. — Eeichardt u. Stiirenburg, Lehrbuch der mikroskopischen
Fhntographie, Leipzig, 1868.— Vogel, Lehrbuch der Photoc/raphie, Berlin,
1874. See also the excellent photographs by E. Koch in Cohn's Seitr.,
vol. 2, and in the Mittheilunyen a. d. Kais. Gesundheits-Amt., vol. 1.

788

METHODS OF INVESTIGATING BACTERIA.

treated, not with acetic acid or alcohol, hut with a weak
solution of carbonate of potash, and under these circum-
stances the nuclei and plasma cells, and in fact all
animal tissues, lose the stain, and the bacteria alone
retain it (Koch),

Methods of
cultivation.

Vessels.

II. The Artificial Cultivation of the Loiuer Organisms.

Artificial cultivation is absolutely essential for the
minute study of the properties of the various micro-
organisms.

The vessels most commonly employed for this purpose
are thick- walled test tubes ; or vessels 5 cm. in diameter
with narrow necks ; or flasks of various sizes, the best
of which are the so-called Erlenmeyer's flasks with flat
bottoms. In order to exclude the
organisms plugs of cotton wool are
employed, which extend for about
3 cm. into the neck of the vessels,
and project about 1 cm. above it; this
must not press too closely on the
walls lest channels be left on the sur-
face of the compact mass. Pasteur
employs small flasks (matras), on the
neck of which a small helmet fits (J5),
which contains the plug of wool (a).
These vessels are move especially
suitable for culture fluids where one wishes to re-inocu-
late frequently ; in this case it is not necessary to take
out the cotton wool plug with the particles of dust ad-
hering to it — the helmet itself is lifted. Fol* employs
a complicated plan consisting of an external cotton wool
plug which remains untouched, in the interior of which
is a glass tube which becomes narrower at the lower part.
This tube contains at the lower part an asbestos, and at
the upper part a cotton wool plug, and when a specimen
is required only the latter is removed, while the asbestos
plug is perforated by a heated canula. — As a rule, how-

* Arch, des sc. pTiys. et natnr., Geneve, 1884, t. 11.

Fig. 140.— Pasteur's
culture vessels.

METHODS OF INVESTIGATING BACTERIA. 789

ever, these precautions are quite unnecessary ; when the
vessels are opened it is sufficient to burn the outer part
of the cotton wool, which contains the dust, in the flame
of the Bunsen burner in order to remove almost entirely
the danger of the introduction of germs.

In many cases where we wish to have a larger surface
of nutrient material we may employ, besides Erlenmeyer's
flasks, small flat glass capsules with vertical walls 1 to
2 cm. in height, and with a diameter of 4 to 6 cm. — the
so-called crystallisation capsules. These are preserved
in a wider cylindrical vessel, 15 to 20 cm. in height, in
which the capsule can be readily raised and lowered by
means of a bent strip of metal ; the cylinder is plugged
with cotton wool in the usual manner. If microscopic
slides or glass plates are employed for cultivation it is
sufficient to preserve them in glass dishes which are well
closed, and it is best for the cover to overlap the lower
part* of the dish.

The nutrient substrata. These must, in correspondence The nutrient
with what has been said above with regard to the con- Sl
ditions of life of the lower fungi and of the necessary
nutrient materials, consist of carbonaceous, nitrogenous,
and mineral substances ; the excellence of the nutrient
solution depends on the nutritive value of the materials
employed, and also on whether the quantities present
approach as nearly as possible the optimum of con-
centration, on whether the reaction is that which is best
for the organism in question, on whether, and in what
quantity, oxygen is present, &c.

If we wish to cultivate mould fungi, and to avoid as far as Formouldand
we can the entrance of bacteria, we must employ a substratum yeas
which is solid, which contains a small amount of water, and
of which the reaction is markedly acid ; in the case of the
yeast fungi the best conditions are obtained by the employ-
ment of fluids which are not so markedly acid, but are still
distinctly so, and which contain a considerable amount of

* A more precise description of the apparatus and the utensils
necessary for the cultivation of bacteria will be found in the special
catalogues of the firms from .which all these articles can be obtained.
The following may be recommended : E. Muencke, Berlin, N.W. ; H.
Eohrbeck, Berlin, N.W.

790 METHODS OF INVESTIGATING BACTERIA.

sugar; for bacteria the most suitable substrata are those
which contain a large amount of water, and of which the
reaction is neutral or alkaline.

As nutrient soil for mould fungi we employ decoctions of
dried plums and other fruits ; decoctions of the fresh dung
of herbivorous animals; decoctions of yeast containing a
large amount of sugar; spread out dung of herbivorous
animals; pieces of bread which may be impregnated with
various decoctions ; a paste made of bread, &c. If the sub-
strata are not sufficiently acid they may be made so by
means of tartaric acid (2 to 5 per cent., according to the con-
centration of the nutrient solution) or phosphoric acid (1 to
1 per cent.). — In the case of yeast fungi we select a decoction
of malt, wort, or one of the above-mentioned decoctions, to
which grape sugar is added ; in the case of bacteria, urine,
hay infusion, meat infusion, &c., to which may be added the
ashes of yeast, cigars, &c., and of which the reaction should
be as far as possible neutral, or at the most very slightly acid
or alkaline.

For saprophy- Pasteur formerly recommended the following as a pure
tic bacteria, artificial nutrient solution: 100 parts of water, 10 parts of
candy sugar, 1 part of tartrate of ammonia, and the ashes
from 1 part of yeast, the weight of the latter being about '075
of that of the whole mixture. Bucholtz replaced the yeast
ashes in this solution by "5 grm. of phosphate of potash.
Cohn selected the following mixture : "1 grm. of phosphate
of potash, '1 grm. of crystallised sulphate of magnesia, *01
grm. of tribasic phosphate of lime, 20 grm. of distilled water,
and "2 grm. of tartrate of ammonia. — These and similar
nutrient solutions were, however, imperfect in various ways,
as has recently been discovered by Niigeli. As the result of
numerous experiments as to the nutriment of the lower
fungi, Nageli recommends the following solutions as normal
fluids for bacteria (from these, solutions suitable for mould
and yeast fungi can be readily prepared by the addition of
sugar and acid) : —

1. Water 100 ccm., tartrate of ammonia 1 grm., biphosphate
of potash (K2HP04) '1 grm., sulphate of magnesia '02 grm.,
and chloride of calcium "01 grin.

Instead of the tartrate of ammonia we may employ acetate
or lactate of ammonia, &c., or even asparagine or leucine.

2. Water 100 ccm., peptone or soluble albumen 1 grm.,
biphosphate of potash (K2HP04) "2 grm., sulphate of
magnesia '04 grm., chloride of calcium '02 grm.

3. Water 100 ccm., cane sugar 3 grm., tartrate of ammonia
1 grm., and mineral salts as in No. 2.

METHODS OF INVESTIGATING BACTERIA. 791

These various nutrient substrata are more or less un- For patho-
suitable for the cultivation of the pathogenic bacteria, genie bacteria.
These organisms evidently require a certain quantity of
albumen and peptone, and sometimes also sugar, and
are very sensitive to variations in the composition of
the nutrient substratum. In the case of the majority of
the pathogenic bacteria, the most favourable medium
must be specially ascertained by experiment.

The following nutrient solutions are the best : meat
infusion (prepared in the same manner as in the pre-
paration of the nutrient jelly) ; meat infusion, with 1 per
<ient. peptone and 2 per cent, dextrose ; solution of
meat extract (Liebig's meat extract, 1 per thousand),
with peptone and dextrose ; milk ; blood serum. We
have also a series of soft but solid nutrient substrata,
more especially boiled potatoes ; mixtures of the nutrient
solutions with solidifying agents, such as gelatine or agar ;
solidified blood serum. All these nutrient substrata
must be neutralised till the reaction becomes faintly
alkaline ; where the reaction is at first markedly acid,
this is done by the addition of concentrated soda
solution, where the excess of acid is slight it is best to
-employ a solution of the acid phosphate of soda.

All the vessels and nutrient substrata must be sterilisation
thoroughly sterilised before their employment, i.e., and
they must be deprived of all living germs. This is done substrata.
by heating the vessels (test tubes, with their cotton wool
plug, &c.) in copper or iron cases kept at a temperature
of 150° to 180° C. for an hour ; at this temperature the
wool is slightly burned; as a rule the temperature
differs at various parts of the oven, and we must there-
fore ascertain in what part the proper temperature is
present. — Larger dishes are washed out with a solution
of corrosive sublimate (1 to 2000), and then they are
repeatedly rinsed with distilled water which has been
sterilised by boiling, or with absolute alcohol. — The
nutrient substrata as soon as they have been intro-
duced into the sterilised vessels are freed from their
germs by boiling them in a steaming apparatus ; accord-
ing to the amount of material they remain for fifteen to

792 METHODS OF INVESTIGATING BACTERIA.

sixty minutes in the current of steam. The mixtures con-
taining gelatine often lose their power of solidification if
the heat has been continued for too long a time ; hence
for these mixtures we employ discontinuous heating, i.e.,
the gelatine mixture is placed on the first day in the
steam for only five minutes; it is then kept till next day
at a temperature of 20° to 30° C., so that any living
spores which have remained behind may germinate ;
it is then exposed to the steam for five minutes on
the second day, and this is repeated on the third day.
— In the case of blood serum, which must be obtained
clear and transparent, temperatures of only 55° to
60° C. are employed, and for five or six days in succes-
sion the material is exposed to this temperature for
several hours (see p. 663).

Special M etlw ds of Preparing some of the Nutrient Substrata.

Nutrient sub- — Potatoes are immersed for half-an-hour in a solution

strata.

Potatoes. of corrosive sublimate in order to kill the resisting spores
present in the particles of earth which adhere to the
outside of the potato ; they are then washed with
sterilised water, i nd cooked for thirty to forty minutes
in the steaming apparatus. They are then placed to
cool in a sterilised and covered vessel, and when they
are cold they are cut by means of a knife which has been
previously heate'd, and is still warm ; the cultivation is
then spread over the freshly cut surface.

Meat infusion. Meat infusion and nutrient jelly. One kilo of good
beef, free from fat, is minced and placed in two litres of
water ; after it has been kept for twenty- four hours at
15° to 20° C., the fluid is drained off, and the solid
material is well squeezed ; the infusion is then placed in
flasks and boiled for one hour in the steaming apparatus*
and then filtered. One per cent, of peptone and half
per cent, of common salt is then added to the filtrate,
which is neutralised with soda solution ; the mixture is
again boiled and filtered, and then introduced into the
cultivation vessels ; these vessels are again sterilised in

Nutrient the steaming apparatus for twenty to thirty minutes. — If
a solid substratum is required we add, in addition to the
peptone and common salt, 5 to 10 per cent, of gelatine,

METHODS OF INVESTIGATING BACTERIA. 793

or 1 per cent, of agar-agar. The gelatine is dissolved by

heat; the mixture is then neutralised, boiled for ten

minutes in the steaming apparatus, and filtered through

a warm filter. If the filtrate is not clear it must be

again boiled, either with or without the addition of white

of egg. The clear filtrate is introduced into the test

tubes or flasks, and sterilised in the steaming apparatus

for five minutes on three successive days. — The agar Nutrient agar.

mixture must be kept for a long time (ten to twelve

hours) in a state of constant simmering over a small

flame, the water being replaced as it evaporates ; it is then

filtered through a warm funnel, or it is poured into a

tall cylinder which is kept in warm water till the muddy

portion is deposited ; it is then allowed to solidify, the

upper clear portion is cut off, dissolved by boiling, and

placed in the various vessels ; these are then again

sterilised by exposure for half hour to the steam.

If possible sheep's blood should be received with anti- Blood serum,
septic precautions in a sterilised vessel and covered with
a sterilised glass plate ; after forty-eight hours the clear
serum is removed by a pipette, transferred directly to
the vessels to be employed for cultivation, and kept at a
temperature of 68° to 70° C. till the serum is solidified.
The vessels are then placed in an incubator, and it is
generally found that the great majority are sterile. — If
it is found impossible to obtain the blood with anti-
septic precautions, it must in the first place be sterilised
as above described at 55° C. on several successive days.
— Instead of killing the germs we may sometimes try to
get rid of them by filtering the nutrient material through
plaster or porcelain (Chamberland's filter).

All the nutrient substrata which are to be employed for
cultivation must be tested before use to see whether they
are sterile ; for this purpose they are kept for some time,
and generally at a high temperature (30° to 35° C.) ; where
the nutrient material is completely sterile no alterations
ought to occur. The substrata are protected against
drying by means of a caoutchouc cap placed over the
wool plug. — Nutrient materials prepared with gelatine
must not be placed at a higher temperature than 20° to

794

METHODS OF INVESTIGATING BACTERIA.

Be-inocula-
tion.

25° C., otherwise they will become liquid ; on the other
hand, agar mixtures and solidified blood serum may be
kept at a temperature of 35° to 39° C.

The inoculation of these sterilised media must be per-
formed with great care ; a small quantity of material
containing the organisms is taken by means of a heated
platinum wire, or of a fine glass tube, and the cotton
wool plug being removed for the moment the wire is
introduced into the nutrient material. In this method
the entrance of organisms from the air is never quite
excluded, but as the danger of contamination from the
air is much less than from the instruments employed,
this source of error is not of any great importance in
practice. However, it is advisable in all cases where we
wish to be certain as to the purity of the cultivations, to
avoid draughts in the room, shaking of the room, &c.,
and if necessary to moisten the floor and the walls. — It
is well for the experimenter to wash his hands in sub-
limate solution before proceeding to the inoculation.

Some

Special Methods of Cultivation.

cial Small cultivations, such as those on hollow micro-
scopic slides, or in the so-called " glass chambers," are

Fig1. 141. — Drop cultivations.
«, the hanging drop. b, the layer of vaseline.

of use for studying the stages of development of a species
Drop cultiva- of bacteria which has already been cultivated pure. The
most simple mode of carrying on these cultivations is by

tions.

METHODS OF INVESTIGATING BACTERIA. 795

placing a small drop of the nutrient solution on the
centre of a sterilised cover glass; the latter is then
seized with heated forceps, turned over, and placed over
the hollow in a sterilised excavated slide. Before doing
this it is well to place a layer of vaseline around the
cavity in the slide, and the cover glass is pressed on this
layer, and thus air is excluded (see fig. 141 ; a, the
hanging drop ; 6, the vaseline layer, which must not
touch the border of the drop). The development of the
bacteria in the drop can then he watched with high
powers of the microscope, either by the use of a warm
slide, or by Watson Cheyne's method (see p. 344).

Access of air is necessary for the development of many
fungi, and the arrangement just described does not
permit it. In these cases Prazmowski has devised an
arrangement by which a small channel leads from the
moist chamber to the outer air, and is not closed by the
vaseline. These moist chambers do not permit a long
observation, because the closure is imperfect, and im-
purities, more especially mould fungi, are generally
found after a few days.

The glass cells employed by von Recklinghausen and Glass cells.
Brefeld are more perfect arrangements. Brefeld's ap-
paratus, which has been specially constructed for the
cultivation of mould fungi and for their observation
with high powers, consists of a narrow glass tube which
dilates in the middle and forms a flattened sphere. The
walls of the chamber are only of the thickness of cover
glasses, and are so flat that an uniformly thin layer of
fluid may be readily obtained in their interior. These
vessels are thoroughly cleaned and freed from fat by
immersion in ether and subsequently in boiling water,
and then the fluid containing the fungus to be examined
is sucked in, so that the inner wall of the chamber is
only covered by a thin layer, and thus an individual
spore can be watched for days with a high power.

Where larger cultivations are required we employ Advantages of
either fluid or solid nutrient substrata. The latter are
most suitable for obtaining and maintaining a pure culti-
vation, and they also form the best means for isolating

796 METHODS OF INVESTIGATING BACTERIA.

individual species of bacteria from a mixture of organisms.
Solid nutrient media had been formerly frequently em-
ployed, but Koch was the first to use them with the de-
finite view of obtaining thereby pure cultivations. — While
in the case of fluids the organisms which are introduced,
and any which may have accidentally entered, become
mixed with each other, so that those that are few in
number are scarcely recognisable among the larger
number of rapidly growing organisms, in the case of
solid substrata the individual species are much more
easily isolated. If we inoculate a species of bacterium at
various parts of the solid nutrient substratum, small
colonies, soon distinctly visible to the naked eye, develop
at each of the points of inoculation ; if extraneous or-
ganisms accidentally fall on the same nutrient soil, they
on their part form isolated colonies which do not usually
mix with those inoculated, and which are readily dis-
tinguishable from them by their colour, form, and con-
sistence ; should, however, the extraneous germ fall on
one of the colonies inoculated, and multiply at the same
part, they usually cause an alteration in the external ap-
pearance of this colony ; and we can ascertain by simple
microscopical observation whether at any part which we
wish to choose for the inoculation of fresh soil impuri-
ties are present. For the second inoculation we only
employ those parts which are found to be quite pure,
and it is in the certainty with which we can find the
material for each further inoculation that we have one
of the greatest advantages of solid as compared with fluid
nutrient substrata. If in the latter extraneous organisms
once enter they spread through the whole medium, and
it is pure chance if we succeed in avoiding one of these
extraneous organisms when we inoculate fresh soil ; the
previous examination of a drop under the microscope is
not sufficient ; for if we find on examination that other
organisms are present it is very difficult to obtain a pure
cultivation. In the case of the solid nutrient substrata,
on the other hand, it is not necessary to avoid altogether
the entrance of other organisms, for in this case, as we can
constantly control the selection of the part for re-inocu-

METHODS OF INVESTIGATING BACTERIA. 797

lation, we have a guarantee for the purity of the second
cultivation.

Among these solid nutrient substrata potatoes are Transparent

. ,, . -vT . , , .. . , , solid nutrient

more especially convenient. JNevertneless, it is better substrata.

if we can obtain a transparent soil, as, for example, by

the admixture of gelatine or agar with the fluid ; on

these transparent soils the majority of the bacteria grow

in a very characteristic manner, and we can distinguish

the colonies very easily, not only with the naked eye,

but also by the aid of the microscope. I have already,

on p. 167, pointed out the most important differences

of the stroke and puncture cultivations on these nutrient

substrata.

It is, however, difficult to isolate the individual species isolation
of bacteria from a mixture by means of stroke and bactena-
puncture cultivations on solid nutrient substrata. If
after the gelatine has been allowed to solidify on a glass
slide we draw several long strokes over the surface with
the infected needle we observe that discrete colonies
appear at various parts of the track, and we can then re-
inoculate from these before they have coalesced with the
other colonies. The more we dilute the material to be
investigated, the more readily do we succeed in obtaining
these discrete colonies. But where numerous species
are present it may very readily happen that the
organisms are carried along the stroke, and that several
species develop at the same place.

On the other hand, the organisms can be very readily Plate cnltiva-
isolated by means of plate cultivations. In this method tlons'
the material to be investigated is in the first place
mixed with the fluid jelly in various degrees of dilution,
and this jelly, containing the subdivided germs, is then
poured out on a cold glass plate, on which it rapidly
solidifies. It is evident that in this method each of the
suspended germs will be fixed at a particular spot, and
if they are not too numerous, isolated colonies will
develop from each organism, and these can be recog-
nised by their characteristic appearance under the micro-
scope, and may be inoculated into test tubes.

For this purpose we employ square, or, better, oblong

798 METHODS OF INVESTIGATING BACTERIA.

plates of about 8 to 12 cm. in length, and 6 to 8 cm. in
breadth. A number of these are sterilised at 180° C.,
and kept in a covered vessel ; the uppermost plate is
always taken, and the gelatine is placed on its lower
surface. We usually employ three plates, of which each
is laid on a large sheet of glass, which is kept level. If
the room is warm it is well to place a vessel contain-
ing cold water or ice beneath this glass plate. A mix-
ture of nutrient jelly and bacteria is then poured out on
its surface. This mixture is prepared in the following
manner: we take three test tubes each containing 8 to 10
ccm. of nutrient jelly, and the gelatine in each is
liquefied by dipping them in water at 40° C. A small
quantity of the material to be investigated is then intro-
duced into the first glass and slowly but carefully mixed
with the jelly ; from this mixture three to five loopfuls
are introduced into the second glass ; this is again
thoroughly shaken up, and from this glass three to five
loopfuls are introduced into the third. The contents of
these three glasses are then poured out on separate glass
plates, the gelatine being equally divided over the plate
by means of a previously heated glass rod. A strip
about 1^ cm. in breadth is left free all round the
margin ; on these free places sterilised glass supports
are placed and fixed with a few drops of gelatine, and
thus several plates may be piled one above the other.
The plates are kept covered with a bell -jar till the gela-
tine is quite firm; after ten to fifteen minutes they can be
placed in a glass vessel and set on one side. The vessel
and its cover are lined with moistened filter paper, and
sterilised in the steaming apparatus. These vessels
may be placed in incubators kept at a temperature of
about 22° C., and are examined every twelve or twenty-
four hours, at first without removing the cover, and later
by examining the plates under the microscope at a mag-
nification of 80 to 100 diameters.

By employing three degrees of dilution as above
described, we almost always find that one of the plates
is good, i.e., it contains a few isolated colonies which
can be counted, and on the other hand not too few

METHODS OF INVESTIGATING BACTERIA. 799

colonies to make it doubtful whether or not they have
arisen from accidental impurities, air germs, &c. If at
least 10, or at most 500 colonies grow on a plate, it is
in most cases a useful plate ; if we only wish to count
the colonies, and not to investigate them further, the
number on the plate may be as great as 5,000. If in
all three plates the numbers are greater or less than
those given it is well to repeat the experiment.

In investigating various questions it is of great im- Enumeration
portance that we should be able, by counting the colonies ^iSiies
which have grown on the plate, to estimate the number
of bacteria which are present in a mixture of organisms.
In order to do this we must add a measured quantity
of the material to the jelly, and afterwards count the
number of colonies accurately. This is most easily done,
when the colonies are numerous, by means of a glass
plate divided into squares. In such a case we only count
a few of the squares, strike an average from the figures
so obtained, and calculate the number in the whole plate.

Similar plates can also be made with nutrient agar. Agar plates.
This material is first liquefied in the tubes by boiling,
and then cooled to 40° C. in a water bath ; the material
is then added to the liquid agar, and the mixture poured
out on the plates. We must employ agar, which be-
comes fluid at 40° C., but solid at 38° or 39° C. The
agar afterwards often expresses water, and as a result
the whole mass may subsequently glide over the glass
plate. It is therefore of importance to line the vessels
in which the agar plates are to be kept only with dry
filter paper; and thus the water as it is expelled from
the agar evaporates so quickly that it cannot collect
between the material and the glass plate.

A modification of the plate cultivations which has Esmarch's
been made by Esrnarch* is very useful for many prac- method>
tical purposes. Instead of flat glass plates he employs
wide test tubes, and the surface of the glass plate is
replaced by the equally large internal wall of the test
tube; while the gelatine is still fluid, and after it has
been mixed with the material under investigation, the

* Zeitschr.f. Ihjyienc, rol. i., Part 2.

800 METHODS OF INVESTIGATING BACTEEIA.

tube is continually rotated in a horizontal position, and
thus as the material cools it solidifies in the form of an
equally thin layer over the whole wall of the tube. The
best way of doing this is to close the tube by means of a
caoutchouc cap, let it swim on cold water, and give it a
slight rotatory motion with the right hand, holding the
orifice of the tube loosely in the left, and keeping it in
the horizontal position. — In order to count the colonies
the outer surface of the tube may be divided into larger
or smaller portions by ink lines. One great advantage
of this method is, that in the case of bacteria which
grow very slowly an opportunity is afforded for their
growth in these tubes, in which contamination cannot
occur. It is more difficult to examine accurately the
individual colonies, and to inoculate from them, than in
the case of the plate cultivations, and it is only in special
cases that this method would be employed when further
cultivations were required.

Where it is important to obtain as complete know-
ledge as possible of all the species of bacteria which are
present, we must vary the nutrient conditions as far as
we can, more especially we must vary the amount of
sugar, the degree of alkalinity, the temperature, and the
amount of oxygen ; in the case of numerous bacteria the
conditions necessary for their artificial cultivation are
not as yet known, and hence it is desirable to vary the
Cultivation of conditions as much as possible. — For cultivating the
bacteria0 anaerobic bacteria Liborius recommends deep layers of
nutrient agar containing 2 per cent, of dextrose. For
this purpose test tubes are filled to a height of about 10
cm. with the nutrient material, and the bacteria to be
investigated are mixed with this material while still fluid
and at a temperature of 40° C. ; the result is that isolated
colonies of the anaerobes grow in the deeper layers.
Instead of this method we may employ vessels contain-
ing nutrient substrata from wilich all the air has been
expelled by means of hydrogen. Vessels of the form
shown in fig. 142 are best suited for this purpose, and
these are filled with the nutrient agar up to the level of the
lateral tube; the material to be tested is then introduced

METHODS OF INVESTIGATING BACTERIA.

801

through the upper opening, while a'continuous stream of
hydrogen is sent through the lateral tuhe, and when it has
passed for a sufficient length of time the tubes are sealed
at a and b. In vessels of this kind we ohtain luxuriant
growth of the most typical anaerobes. If we wish to
obtain the colonies of the anaerobes in such a way that
they may be examined under
the microscope, we employ
little vessels containing a layer
of the nutrient material at
least 1*5 cm. in depth, and
these vessels are placed in an
iron case with a tight fitting
cover and provided with stop-
cocks, by means of which hy-
drogen can be passed through
the vessel and all the air driven
out. For further details, see
Liborius, Zcitschr.f. Hygiene,
vol. i., part 1.

If we have to do with bac-
teria which will not grow on
solid nutrient substrata but
only in fluids, the difficulty of
isolating them is much greater.
This was formerly done by
Klebs' method — the so-called
method of fractional cultiva-
tion ; in this method a vessel
is in the first place inoculated
and the bacteria are allowed to grow; a small quantity
is then taken from the first vessel and introduced into
a new nutrient material ; this is again allowed to
develop, and the process repeated through a series of
cultivations. In this method the cultivations gradually
become purer and contain only those organisms which
grow most quickly under the conditions present, while
the chances of the presence of the more slowly grow-
ing organisms become constantly less. This method
is, however, not as a rule of much use, because it is not

51

Fig. 142.— Apparatus for the
cultivation of anaerobes.

Isolation of
bacteria in
fluid nutrient
substrata.

Fractional
cultivation.

802 METHODS OF INVESTIGATING BACTERIA.

always the most quickly growing organisms which interest
us; it is true that by varying the external conditions,
more especially the temperature, we may vary the species
of organism which grows most quickly in the mixture ;
but the method is always uncertain and tedious, more
especially as we know very little as regards the most
favourable conditions for the growth of the various kinds
of organisms.

Dilution A much better plan is that of diluting the material to

a great degree. This principle was first recommended
by Brefeld, and then by Na'geli and Buchner, and Brefeld
employed it more especially for the purpose of inocu-
lating the moist chambers described above. According
to Brefeld a small quantity of the material is taken and
mixed thoroughly with pure sterilised water; the dilution
is carried to such a degree that in the quantity contained
on the point of a lancet-shaped needle only one germ
should be present. When we have convinced ourselves
by microscopical examination that this condition has
been complied with, we then introduce this amount into
each of a series of vessels, and if we employ a large
number of vessels, and if in these the same organisms
develop which are most numerous in the material em-
ployed, the chances are that only one germ was present
in each drop. In some of the vessels we will find
examples of the other organisms which are present in
smaller numbers in the material. If we are isolating
mould fungi, the spores of which are difficult to see, it
is well to employ a nutrient solution instead of water, in
order that the spores may sprout, and thus become
larger and more easily visible, and then to dilute the
material in the manner above described.

In the case of the bacteria the microscopical examination
is, as a rule, of but little value, because the spores, and
even the fully grown organisms, are so small that it is
practically impossible to ascertain the presence of a single
germ in one drop. In this case we can only get an approxi-
mate idea as to the amount of dilution from the micro-
scopical appearances. The whole process rests on the
assumption that the organisms in which we are interested

METHODS OF INVESTIGATING BACTERIA. 803

were present in relatively large numbers in the material
employed, and in many cases, even where we have to do
with pathogenic organisms, this condition is prohably
fulfilled; where, however, saprophytes of various kinds
are present in great excess, it is hardly feasible to hope
for complete separation by this method.

In some cases it is well to combine the plate method
and the dilution method in order to obtain good results.

The whole method of pure cultivation must of course
be practised in the first instance with some typical ex-
amples. As good specimens for this purpose I would
recommend the cultivation of bacillus prodigiosus on
potatoes, gelatine, &c., at various temperatures; the
cultivation of anthrax bacilli on potatoes, nutrient jelly,
blood serum, and in fluid substrata, likewise at various
temperatures ; the cultivation of Aspergillus flavescens
on slices of potato at a low temperature (15° to 20° C.,
&c.). If every one who attempts the cultivation of
fungi, and especially the isolation of pathogenic organ-
isms, would first test their knowledge with these typical
examples, a great many imperfect papers would remain
unpublished.

Having succeeded in obtaining a pure cultivation of A further

A . . , differcntia-

an organism, we have next to determine its morplio- tion of the
logical and biological characters. We have to ascertain
what are the nutrient materials, and what the tempera-
ture which most favour its growth, and whether, and in
what degree, it requires the presence of oxygen ; we have
to test whether it is able to excite fermentation, and for
this purpose we have to add the most important of the
fermentescible substances (carbo-hydrates, the higher
alcohols, fatty acids, albuminous materials, &c.) to the
ordinary nutrient materials, and under the other
conditions necessary for the growth of the organisms.
We have further to ascertain whether the organism
isolated has any pathogenic action ; inoculation experi-
ments must be made on a variety of animals, more
especially on mice, which are so very susceptible
to infective diseases, and also on guinea-pigs, rabbits,
monkeys, &c. These experiments must be carried out

804

METHODS OF INVESTIGATING BACTERIA.

with smaller and larger doses, and the organisms must
be introduced either by superficial inoculation, or by in-
jection into the subcutaneous tissue, or by direct injec-
tion into the blood stream. If the animals become ill
or die similar attempts at cultivation and inoculation
must be made with their blood or organs, and the
identity of the organisms inoculated with those found
must be ascertained. All these experiments must be
frequently repeated. — Lastly, we must make experi-
ments as to the conditions of death of the organisms, and
more especially as to the loss of their pathogenic pro-
perties, and we must ascertain what external conditions
and what disinfecting means can most readily cause
their destruction (see p. 653).

Examination
of air.

Miguel's
method.

3. Bacteriological Investigation of Air, Water, and
Soil.

a. Air. — Attempts were formerly made to ascertain
the number, species, and vitality of the organisms pre-
sent in the air by fixing the
germs on sticky surfaces, and
by subsequent microscopical
examination. These attempts
were, however, failures, but in
recent times fresh methods have
been devised, the essential aim
of which is to obtain a develop-
ment of the individual germs,
and then to count the colonies.
Miquel employed for this pur-
pose a fluid nutrient substra-
tum, a broth prepared some-
what after the method described
on p. 792 : this material was in-

Fig. 143.— Miquel's ap-
paratus for the investi- troduced into a large number oi

small glass vessels of the form

shown in fig. 143. These sterilised vessels were fixed in a
stand, the end/ was connected with an aspirator, and the

METHODS OF INVESTIGATING BACTERIA. 805

point a was heated and then broken off. A small
quantity, 1 to 3 litres, of air was drawn through the
fluid and the point a was sealed, the plug c, composed
of spun glass, and which might have taken up some of
the germs, was blown back into the fluid, and the ap-
paratus was placed in an incubator. In each of these
experiments 20 to 50 vessels were employed ; after some
time it was ascertained in how many of these muddi-
ness had occurred as the result of the development of
bacteria, and if this did not occur in all the vessels, but
only in a small proportion of them, it was assumed that
in each of the muddy vessels only one germ had entered.
Hence the number of the vessels in which develop-
ment occurred gave also the number of the germs which
were present in the quantity of air aspirated through
all the vessels. If none of the tubes became muddy, or
if, on the contrary, they all became turbid, the experi-
ment was repeated with larger or smaller quantities of
air ; if all the tubes had become turbid it was only
possible to obtain the approximate minimal number of
the organisms present, for in each case the muddiness
might have been due not only to one but even to two, or
ten, or more germs.

As is quite evident, the utility of this method rests on Sources of
the assumption that the germs are very equally dis- me
tributed in the air, and that they do not exist in masses.
All other observations, however, show that this assump-
tion is incorrect. Direct microscopical observations
demonstrate that there are numerous collections of
bacteria among the germs present in the air, and that
they are by no means equally distributed through-
out the air. — Besides, the whole method is extremely
troublesome, and does not permit any sufficient varia-
tion of the nutrient media.

Hesse has attempted to utilise the solid nutrient sub- Hesse's
strata for the investigation of air. A glass tube, 70 cm. m
in length and 3' 5 ccm. in width, is filled with 50 ccm. of
nutrient jelly in such away that the inner wall is lined with
the material, and that a thicker layer of it is present at
the lower part of the tube. One end of the tube is closed

806 METHODS OF INVESTIGATING BACTERIA.

with an india-rubber cork, the centre of which is per-
forated, and contains a glass tube plugged with cotton
wool ; this glass tube is connected with the aspirator,
the other end is covered with a caoutchouc cap, in which
there is a central hole through which the air enters.
The whole tube is placed on a stand in a horizontal
position.

The germs present in the air fall — usually shortly
after the entrance of the air into the tube — on the
gelatine, and develop there to form isolated colonies.
By this method we often obtain very instructive appear-
ances, but even this method does not give accurate
comparative results. For one thing, it is difficult to
ascertain the proper rapidity of the current of air, so
that no germs shall pass through the tube, and yet that
they shall not be too numerous near the entrance of
the tube ; again, the dry surface of the gelatine is
not a suitable place for the commencement of develop-
ment; and, lastly, a mass of organisms gives rise to
colonies which are equally well isolated as those which
develop from a single individual.

Other Other attempts to determine quantitatively the germs

of the air have also as yet failed in giving entirely satis-
factory results. Yon Sehlen's attempts to employ agar
nutrient solutions are open to the error that rapidly grow-
ing saprophytes may enter these nutrient materials while
the air is being slowly drawn through them ; and further,
that it is difficult to retain the germs in the fluid, and

Kault8x£f . also to vary the composition of the nutrient substratum.

the methods as J

yet employed, — It seems best to employ indifferent substrata for the re-
tkms for their ception of the germs of the air. This can be best done by
improvement, the use of cotton wool, glass wool, and similar substances.
The material employed for the filtration of the air, and
laden with the air germs, is then put into nutrient jelly,
and after this has been shaken up for about half an hour
(in order to break up any colonies that may be present)
it is poured out on plates. If we wish to employ a
variety of nutrient substrata the material used for
the filtration is in the first place shaken up with salt
solution, and equal known quantities of this solution are

METHODS OF INVESTIGATING BACTEBIA.

807

added to the various nutrient substrata. — Attempts
carried out on those principles seem to promise useful
results, hut as yet this method has not heen sufficiently
tested.

b. Water. — The specimens to be investigated must be investigation
taken in sterilised vessels with glass stoppers, or, in order £*
to avoid contamination which is very apt to occur during specimens,
the transport, in small glass bulbs devoid of air and sub-
sequently sealed. These glass bulbs have a diameter of
about 1^ cm., and are provided at
one side with a glass tube almost of
capillary thickness, and 10 to 15 cm.
in length.* By warming the bulb,
and subsequently immersing it in
distilled water it is about half filled
with water; it is then placed on a
stand, the glass tube being directed
obliquely upwards, and surrounded
with filter paper; the water in the
bulb is then brought to the boil, the
steam streams out of the capillary
tube, and any drops of fluid which
may be carried with it are soaked up
by the filter paper. When all the
water, with the exception of half a
drop, has been volatilised the capil-
lary tube is sealed while the stream
of steam is still passing.

These tubes are carried in this state,

and can be readily sent over considerable distances in tin
vessels with a wooden bottom in which two hollows are
present. — In taking the specimen to be tested a solution of
sublimate (1 to 2,000) is poured over the bulb and the
hands of the experimenter, and then the sublimate is re-
moved by a portion of the water to be tested. When it
has been quite removed, the capillary tube is broken near
the point (at a) under water, which then rushes into and
fills the bulb. The tube is then sealed (at I) in the flame

* These glass bulbs are readily prepared by means of a blow-pipe,
or they can be obtained from any glass manufactory at a price of from
3d. to 7(/. per dozen.

Fig. 144. — Apparatus
for collecting water.

808 METHODS OF INVESTIGATING BACTERIA.

of a spirit lamp. — When these bulbs are brought back to
the laboratory they are again disinfected and washed with
sterilised water. A mark is made with a file close to the
junction of the tube with the bulb (at c), and the tube
broken off at this point. The resulting opening is suffi-
cient to enable one to remove the desired amount of
water — a drop to a cubic centimetre or more — by means
of a sterilised pipette.

Investigation. The best method of ascertaining the number and
species of the germs present is by means of gelatine
plates, or by Esmarch's method. In order to obtain
useful plates (containing 10 to 5,000 colonies), it is well
to make the first experiment with from 1 to 10 drops of
water ; according to the result of this experiment we can
employ in the subsequent attempts either larger quantities,
or we can dilute the water with sterilised distilled water.
If, however, we cannot again obtain a fresh specimen of the
water to be tested we mast at first make a large number
of plates containing varying amounts of the water.

Error as the It is of importance to examine the water as soon

result of keep- . .

ing a specimen as possible, at any rate within one to three hours after it
has been obtained. This precaution is essential, in view
cf the fact that has now been confirmed by many in-
vestigators that the bacteria in the water multiply rapidly
if it is kept in a warm place (see p. 711). In trans-
porting the water it should be packed in ice; Wolffhiigel
has indeed ascertained that when water is preserved in
ice the number of living germs present gradually di-
minishes ; but the diminution is not so marked during
the first twenty-four or forty-eight hours as to make any
essential difference in the result. The great point is to
avoid as far as possible any delay in the investigation.

Fol and Dunant have described a method of analysing
water which is closely similar to Miguel's method of
examining air, but it also possesses all the errors of this
method, and is not of any practical use.*

In judging the results of the investigation we have to
bear in mind the points which have been referred to on
p. 714.

* See Boltoi, Ztitschr.f. Hygiene, vol. 1, Part 1.

METHODS OF INVESTIGATING BACTERIA. 809

c. Soil. — As yet no accurate methods of investigating investigation
the bacteria of the soil have been published. The of s
author has found that the best method is to take a
small known quantity of the soil and mix it with a
known quantity of sterilised distilled water ; the mixture
is thoroughly shaken up for a half to one hour ; and then
various quantities of the fluid are taken and employed,
as in the case of the examination of water, for a number
of plate cultivations. — In the case of the soil, also, it is
of importance to examine the specimen as soon as
possible after it has been taken, because the saprophytes
multiply rapidly in the laboratory as the result of the
higher temperature. No trustworthy method has been
published with regard to taking specimens of the soil at
various depths in such a wray that all contamination
from without and from the adjacent layers of soil is
avoided.

It is of extreme importance in the interest of hygienic
investigation that the methods of the bacteriological in-
vestigation of air, water, and soil should be improved.

LONDON :

Printed by JAS. TKVSCOTT & SON,
Suffolk Lane-. B.C.

INDEX.

PAGE

Abbe's sub-stage condenser ... ... 786

Abscess formation in rabbits ... 210

Absolute alcohol, action on spores ... 666

Acclimatisation of bacteria 679

Acetic fermentation 618

bacteria of 389

conditions of 619

fermentative agents 618

materials necessary for ... 618

relation of organisms to ... 619

Acetone, action on spores ... ... 666

Acquired immunity 752

degrees of 753

explanation of ... ... 753

Acrasiaa ... 143

Acrospores 106

Acrostalagmus cinnabarinus 113

Actinorhycosis in man 140

Actinomyces 138

Aerobes 530

— obligatory 533

^Sthylic alcohol, formation of, by

fermentation 601

Agar plate cultivations 799

— preparation of, for cultivations 793
Air. bacteriological investigation of 804

— occurrence and behaviour of

bacteria in 687

— transport by currents of ... 740
Air germs, deposit of, by condensation

of water vapour 690

errors in the recent investi-
gations on 691

origin of 687

weight of 688

Alcohol as an inhibitory agent ... 654

— influence of amount of, on fer-

mentation 594

Alcoholic fermentation of sugar by

yeast 588

Alcohols, fermentation of the higher 602

Allyl-alcohol as an inhibitory agent . . . 653

Alum, action on spores ... ... 666

Alvarez and Tavel on smegma bacilli 291

A mido bodies as nutriment for bacteria 550

Ammonia, action on spores ... ... 666

Ammonium sulphide, action on spores 667

PAGE
Anaerobes ... 530

— cultivation of ... 800

— facultative 532

— in relation to putrefaction ... 614

— obligatory 532

— source of energy in 545

— which excite putrefaction ... 38 ">

Anaerobic parasites 639

Analysis of anthrax bacilli 526

— of bacteria 252

— of Friedlaender's pneumonia

bacilli 526

— of micrococci 526

— of the ashes of the fission fungi 527

— of the budding fungi 516

— of the mould fungi 502

— of the vinegar plant 526

Aniline dyes, Ehrlich on 780

Antheridium 107

Anthrax bacilli, analysis of 526

attenuation of 657

degrees of attenuation ... 657

Koch on spore formation in 538

Pasteur's views on the at-
tenuation of 658

— products of 572

Anthrax, protective inoculation

against 757

— source of infection of 738

— spread of... 732

Anthrax-protein 526

Apparatus for disinfection by steam 772

Aquatic bacteria 711

Area Celsi, micrococci in 203

Arloing, Cornevin, and Thomas, on

the bacillus of Rauschbrand ... 299
Aromatic bodies, production of, by the

lower fungi 561

Arseniate of potash as an inhibitory

agent ... 653

Arsenious acid, action on spores ... 667

Asci 106

Ascococcus Billrothii 231

Ascomycetes 108

Asco.-pores 106

Ashes of fission fungi, analysis of ... 527
Ashes of yeast, analysis of ... ... 518

812

INDEX.

Aspergilli, pathogenic properties of... 123
Aspergillus 119

— albus 122

— clavatus 122

— distribution of ... 126

— flavus 121

— fumigatus 121

— infective, temperature optimum

of 125

— niger 121

— ochraceus 122

— parasitic, occurrence of, in birds 124

in mammals ... ... 125

in man 125

Assimilation by the bacteria... 543, 545
Atmospheric pressure, influence of, on

bacteria... ... 535

in relation to yeast ... ... 521

Attenuated anthrax bacilli, return of

virulence of 658

Attenuation of anthrax bacilli ... 239

by carbolic acid ... 659

by chromic acid ...659

by heat 656

by sulphurous acid ... 659

chicken cholera bacilli ... 317

pathogenic and fermentative

organisms 655

Kauschbrand bacilli 300

the bacilli of chicken cholera 660

the virus of rabies 660

Author's suggestions as to the best
method of examining air for
bacteria 806

B.

Babes on red sweat ... 225

Bacillary necrosis of the liver ... 350

Bacilli, characters of the ... ... 172

Bacilli in malaria 294

— in smegma 291

— key for the diagnosis of ... 411

— of saliva 319

— pathogenic in animals ... ... 299

— pathogenic in man ... ... 234

— with no known pathogenic pro-

perties ... 351

Bacillus 156

— aceticus ... ... 389

— acidi lactici 363

— aerophilus 398

— alvei 343

— anthracis 234

— butyricus ... ... ... 366

— butyricus (Hueppe) ... ... 372

— butyricus (Liborms) ... ... 371

— butyricus (Prazmowski) ...367

— butyricus, products of ... ..... 612

— caucasicus ... 372

— causing erysipelas in the ear of

rabbits ... .. 350

PAGE

Bacillus cavicida 333

fermentation of carbo-hy-
drates by 601

— choleras gallinarum 314

— coprogenes foetidus 379

products of 612

parvus 333

— crassus sputigenus (Kreibohm) 322

— cuniculicida (Koch) 312

— cyanogenus 361

— diphtherias (Loeffler) 280

columbarum (Loeffler) ...826

vitulorum (Loeffler) 328

— dysodes ... 374

— erythrosporus 357

— Fitzianus 388

as a ferment of glycerine ... 602

— fluorescens liquefaciens ... 358

products of 612

putidus ... ... ... 357

products of 612

— fuscus 360

— Hansenii 409

— janthinus 361

products of 612

— leprse 274

— liodermos 401

— luteus 359

— mallei 277

— megaterium 407

— mesentericus fuscus 399

vulgatus 400

— multipediculus ... 401

— murisepticus (Koch) 310

— mycoides 403

— neapolitanus ... 335

— necrophorus ... 338

— cedematis maligni 242

— of jequirity ophthalmia ... 346

— of Kauschbrand 299

— of rhinoscleroma 291

— of swine erysipelas 302

— of syphilis 288

— oxytocus perniciosus 332

— parvus ovatus 339

— Pasteurianus 390

— pneumonias (Friedlander) ... 255
fermentation of carbo-hy-
drates by 601

— pneumonicus agilis ... ... 325

— polymyxa 374

— prodigiosus 352

products of 612

— pseudopneumonicus ... ... 324

— putrificus coli ... ... ... 376

products of 611

— pyocyaneus, as a ferment of

glycerine 602

products of ... ... ... 612

• — pyogenes foetidus ... ... 375

products of 612

— ramosus liquefaciens 402

INDEX.

813

PAGE

Bacillus saprogenes 377

products of 611

— septicus agrigenus 318

sputigenus (Fraenkel) ... 325

— subtilis 394

analysis of ... 526

— synxanthus 360

— tetani 340

— tremulus 409

— tuberculosis 260

— tumescens 409

— typhi abdominalis 248

— ulna 409

— ureae (Leube) 390

products of 612

Bacteria, analysis of 525

— arthrospores in ... ... 161, 163

— assimilation by 543,545

— characters of the cultivation of 164

— classification of 169

— Cohn's classification of... ... 177

— conditions of spore formation

and spore germination of ... 537

— de Bary's classification of ... 179

— destruction of. in the body ... 643

— diagnosis of, from tissue ele-

ments 787

— distribution of ... 685

— endospores in 161

— fermentation by ... ... 595

— fermentatjon of sugar by ... 590

— from mud, or the intestinal

contents of ruminants, pro-
ducts of 612

— germination of spores of ... 163

— growth in meat jelly 165

— habitat of (5S5

— in articles of food 716

— in dwelling houses 719

— in clothing 718

— influence of atmospheric pres-

sure on ... 535

— influence of concurrent growth on 53 7

— influence of electricity on ... 535

— influence of fermentative ac-

tivity on the life of 536

— influence of light on 5 '35

— influence of mechanical move-

ment on ... 535

— influence of temperature on ... 536

— in refuse 720

— in the intestine ... 724

— in the mouth 723

— in the soil 693

— in the soil under floors... ... 719

— in the stomach 724

— involution forms of 156

— means for the destruction of ... 662

— method of diagnosing 176

— methods of investigating ... 777

— movement of ... 159

— multiplication of 160

PAGE

Bacteria of putrefaction 375

— on the respiratory mucous mem-

brane 724

— on the skin ... .;. ... 723

— on the surface of the body ... 723

— parasitic, in plants 636

— propagation of, by spores ... 161

— reaction of the nutrient medium

in relation to 534

— relation of concentration of the

nutrient medium to 533

— relation of, to oxygen 530

— spores of 156, 162

— staining of 778

— structure of cells of 158

— transport of 687

— vegetative forms of 155

— with variable vegetative forms 175,

484

— Zopf's classification of 180

Bacteriological investigation of air,

water, and soil 804

Bacterio-purpurine 490

Bacterium 156

• — brunneum 360

— chloriiium 359

— coli commune 334

— janthinum ... 361

— lactis aerogenes 335

— lactis, nutrient materials neces-

sary for 529

— lineola 388

— merismopedioides 410

— syncyanum 361

— synxanthum 360

— termo 387

— relation of temperature to ... 536

— Zopfii 405

Basidia 105

Basidiosporese ... 108

Basidiospores 106

Bassi on muscardine 94

Beer yeast 589

Bees, bacillus of foul brood of ... 343
Beggiatoa 174, 488

— alba '489

— mirabilis 490

— roseo-persicina 490

— sulphur in 526

Behaviour of bacteria in the air ... 687

— of bacteria in the soil 691

Benzoate of soda as an inhibitory agent 654
Benzoic acid, action on spores ... 666

as an inhibitory agent ... 653

Benzole, action on spores 666

Bichloride of mercury, action on

spores ... ... 667

as an inhibitory agent ... 653

Bienstock's bacilli from fjeces 333, 404

— putrefactive bacillus from f a3ces 376
Billroth's objections to the parasitic

theory ... 97

814

INDEX.

PAGE

Biological relations between the
higher plants and the fungi,

former views as to 495

Biology of the micro-organisms ... 495
Birds, mould fungi as parasites in ... 634

Black yeast ... 154

Blight fungi 109

Blood serum, preparation of, for cul-
tivations 793

Blue milk, bacillus of 361

Boracic acid, action on spores ... 667

as an inhibitory agent ...653

Borax, action on spores ... ... 666

Bostroem on cultivation of actino-

myces ... ... 141

Botrytis 115

Bread, fermentation of 606

Bref eld's glass cells 795

Brefeld on temperature in relation

to bacillus subtilis 536

Brieger's analysis of Friedlaender's

pneumonia bacilli ... ... 526

Brieger on ptomaines... ... ... 569

Bromine as a disinfectant 669

— as an inhibitory agent ... ... 653

Bromine water, action on spores ... 667
Buchner on the staining of spores ... 785

— on the variability of anthrax

bacilli 240

Budding fungi as infective agents ... 636

chemical composition of ... 516

conditions of life of ... ... 516

conditions of spore formation

and spore germination of ... 523

nutrient materials of ... 518

Bumm on the coccus of gonorrhoea... 199
B uty ric acid fermentation ... ... 5 9 7

fermentative agents of the 598

materials necessary for ... 597

nature of the decomposi-
tion of 598

Bye products in the alcoholic fer-
mentation of sugar 590

0.

Cadaverine 569

Calomel as a disinfectant 654

Camphor as an inhibitory agent ... 654
Carbo-hydrates, bacilli causing fer-
mentation of 363

— fermentation of, by bacteria ... 595
Carbolic acid, action on bacteria ... 667

action on spores ... ... 667

as a disinfectant 671

as an inhibitory agent ... 654

Carbon, assimilation of, by the lover

fungi ... 546

— sources of, for the fission fungi . . . 528
— of, for the mould fungi ... 504

of, for yeast 519

Carbonic acid as a product of the

lower fungi 560

Cellulose fermentation 600

— solution of, by the butyric acid

bacillus' 578

Cerebrospinal meningitis, micrococci

in 203

Charbon symptomatique, bacillus of 299
Charrin's septicemie consecutive au

charbon 207

Chaveau on protective inoculation in

anthrax 757

Cheese spirilla 477

Chemical composition of the budding

fungi ... 516

of the fission funei ... ... 525

of the mould fungi 502

Chemical ferments ... ... ... 574

roleof 575

— poisons as inhibitory agents of

bacterial growth 651

Cheyne's method of studying spore

formation and the sprouting

of spores ... 795

Chicken cholera, attenuation of the

bacilli of 660

bacillus of 314

protectiveinoculation against 75(5

Chinolin as an antiputrefactive agent 655
Chlorate of potash, action on spores 666
Chloride of calcium, action on spores 666
Chloride of iron, action on spores ... 667
Chloride of lime, action on spores ... 667
Chlorine as a disinfectant 669

— as an inhibitory agent ... ... 653

— water, action on spores 667

Chloroform, action on spores ... 666

Cholera, acquired immunity ... ... 447

— artificial production in animals 438

— bacillus 415

— contagiousness of ... ... 734

— Emmerich's bacillus of 335

— endemic occurrence 451

— factors predisposing to 447

— influence of individual predis-

position on 446, 460

— influence of the soil on ... 457
— local and seasonal variations

in ... ... 7(55

— localistic view 4(57

— local predisposition 453

— meteorological influences ... 455

— modes of transport of the infec-

tive agents of ... ... ... 444

— natural mode of infection ... 422

— on ships 450

— Pettenkofer's views on 468

— points of entrance of the infec-

tive agents into the body ...444

— present mode of spread of ... 452

— prophylactic measures against 449

— prophylactic regulations against 470

INDEX.

815

PAGE

Cholera, protective arrangements in

the healthy body 446

— seasonal predisposition ... ... 453

— sources of infection ... 443,738

— transmission by the sick ... 451
Cholera nostras, relation of Finkler

and Prior's spirillum to ... 476

Choline 569

Citrate of lime, fermentation of ... 605

Claclothrix 174

— dichotoma 491

Clathrocystis roseo-persicina ... 490

Claviceps purpurea 113

Cleospora ... 115

Clostridium 156

Clothing, bacteria in 718

Clou de Biskra 188

Cochin on the time required for fer-
mentation 593

Cohn's nutrient solution 790

Comma bacillus 415

Common salt as an inhibitory agent 654
Concentration of the nutrient medium

in relation to the bacteria ... 533
Concurrent growth of bacteria ... 537

of mould fungi with other

organisms 513

of yeast with other fungi ... 522

Conditionsof life of the budding fungi 516

of the fission fungi ...525

of the lower fungi ... 501

of the mould fungi ...502

Conidia 106

Constancy of the characters of the

fungi 672

— of the products of tissue change 564

Contact, transport by 739

Contagion by direct contact ... 730

— by surrounding objects 731

Contagious facultative parasites ... 732

sources of 738

— infective diseases 730

— obligatory parasites 732

sources of infection by ... 736

Contamination of the soil 722

Cordua on zoonotic finger erysipeloid 201

Cordiceps isaria 115

Corrosive sublimate as a disinfectant 670

Cover glass preparations 778

Crcnothrix 174

— Kiihniana 486

Cryptococcus xanthogenicus ... 203

Cultivation of anaerobic bacteria ... 800

— of micro-organisms 788

— special methods of 794

D.

Dahlia... 782

Davaine on progressive virulence ... 682
Death of the lower fungi, conditions

affecting the 647

PAGE

De Bary on bacillus megaterium ... 407
classification of the parasitic

fungi 628

Decay 616

Degenerative changes in the fungi,

variations as the result of ... 676
De la Croix on the action of chemical

agents on bacteria 651

Deneke on cheese spirilla ... ... 477

Dental caries, bacilli in 298

bacteria in ... 391

Destruction of bacteria by chemical

poisons 665

— by steam 665

in the blood 742

— means for 662

Dextran fermentation 600

Dextran fermentation of sugar ... 215
Diagnosis of bacteria from tissue

elements 787

— of the bacilli, key for 411

— of the micrococci, key for ... 232

— of the spirilli, key for 485

Diastase, chemical composition of ... 581

Diastatic ferments 576

Dilution, separation of bacteria by. . . 802
Diphtheria in calves, bacillus of ... 328

— in pigeons, bacillus of 326

— Loeffler's bacillus of 280

— micrococci in 202

— sources of infection of 737

Diplococcus albicans tardissimus ... 230
Disinfection 647

— by steam 772

— experiments, conditions of ... 647

— natural means of ... ... 685

— of dwelling-houses 775

— of excreta ... 772

— of linen, beds, &c. 772

— Schiitte's regulations for ... 776

Dispora caucasica 372

Distilled water, action on spores ... 666

Distribution of bacteria 685

Double staining 782

Drainage, advantages of 721

Drinking water in relation to

typhoid fever 767

Drop cultivations 794

Drying, influence of on cholera bacilli 433
Dry zone in relation to the spread of

bacteria from the soil ... 707

Duclaux, on the coagulation of caseine

by bacteria 580

Dujardin-Beaumetz on sulphurous

acid as a disinfectant 669

Dulcite, fermentation of ... ... 603

Duodenum, injection of cholera

bacilli into 436

Durin and Schebler on the analysis of

bacteria P27

Dwelling-houses, disinfection of ... 775

816

INDEX.

E.

PAGE

Earth bacillus ... 403

Ehrenberg ... 69

Ehrlich on Mastzellen 787

— on the aniline dyes ... ... 780

Eidam on temperature in relation

to bacterium termo ... ... 536

Electricity, influence of, on bacteria 535
Embolism by bacteria ... ... 641

Emmerich's bacillus of cholera ... 335
Emmerich on bacteria in diphtheria 287

— on cholera bacilli 420

— on pneumonia bacteria out-

side the body 259

Empusa muscle ... ... ... Ill

— radicans 112

Emulsine, chemical composition of... 581

Endocarditis ulcerosa 197

Endosporium 107

Endothelial cells, relation to bacteria 644
Endothelium, importance of , in regard

to infection 750

Energy, development of, by the lower

fungi 544

— interchange of, in the lower fungi 557

— source of, in the case of the

anaerobes ... 545

Engelmann on the influence of
oxygen on the movement of

the bacteria 531

Entomophtoreaa ... Ill

Enzymes ... ... 574

Epidemic anthrax, mode of occur-
rence of 239

Epidemic diseases of plants, factors

which influence their spread... 632

of plants, relation to season

and locality 631

Episporium 107

Epithelium, importance of, in regard

to infection 750

Ergot 113

Erlenmeyer's flasks ... ... ... 788

Erysipelas, sources of infection of ... 738

Erysiphae oidium 126

Erythrite, fermentation of 603

Escherich on bacilli in the fasces of

infants... 334

Esmarch's method of separating bac-
teria 790

Ether, action on spores 6(5(5

Etiology of cholera 421

Eurotium 119

— aspergillus glaucus ... ... 123

— repens 123

Exanthemata, sources of infection of 737
Excrementitious nitrogenous pro-
ducts of the lower fungi ... 550

Excreta, disinfection of 772

Excretion of infective agents by the

sick 735

Excretory products, nitrogenous ... 550

PAGE

Excretory products, non-nitrogenous 553

Exoascus taphrina 146

Expired air, absence of bacteria in the 727
External conditions, variations in, as
influencing the products of
time change 679

F.

Facultative anaerobes 532

— parasites 629

— saprophytes 629

Fasces, Bienstock's bacilli of ... 404

Falkenheim on sarcina ventriculi ... 326
Fate of non- nitrogenous materials in

the lower fungi ... ... 553

— of the parasitic bacteria outside

the body 686

Fatty acids as anti-putrefactive sub-
stances... 655

fermentation of 603

production of, by the lower *

fungi 560

Favus, fungus of 127

— of mice, fungus of 130

Fermentation 586

— acetic 618

— and tissue change ... ... 623

— a physiological act of living

organisms 623

— as a substitute for oxygen in

supplying energy 545

— by bacteria 595

— butyric acid ... 597

— of cellulose 600

— chemical changes in ... ... 621

— classification of ... 587

— definition of 586

— dextran ... 600

— influence of oxygen on... ...595

— influence of the quantity of

yeast on 594

— influence of temperature on ... 594

— influence of the amount of

alcohol on ... 594

— influence of the amount of

sugar on 594

— lactic acid ... 596

— of bread 606

— of carbo-hydrates by bacteria ... 595

— of glucose, chemical process of 590

— of the fatty acids 603

— of the higher alcohols ... ... 602

— products of 562

— time required for 593

— viscous ... ... 598

Fermentative action of the mould

fungi ... 511

relation to acids- 584

— relation to temperature ... 583
Fermentative activity as a substitute

for oxygen 531

INDEX.

817

PAGE

Fermentative activity, influence of, on

the life of the bacteria ... 536
of yeast ... 522

Fermentative organisms, attenuation

of 656

Fermented fluids, scums on ... ... 151

Ferments and true fermentations,

distinction between 585

— chemical 574

— chemical composition of ... 581

— formation of, by bacteria ... 530

— method of separating ... ... 581

— mode of action of ... 582, 585

— relations to carbolic ticid ... 584

— relations to salicylic acid ... 584

— which break up glucosides .. 580

— which decompose fat ... ..580
Finkler and Prior's spirillum ..472
Fission fungi as causes of disease .. 636

chemical conditions of .. 525

conditions of life of... .. 525

granulose in .. 527

nutrient materials of .. 527

sources of carbon of .. 528

sources of nitrogen of ... 527

Fish, mould fungi as parasites in ... 634
Fitz on the fermentation of dulcite... 603

— on the fermentation of erythrite 603

— on the fermentations of glycerine 602

— on the fermentation of mannite 603
Flacherie, micro-organisms in ... 207
Flies, parasitic mould fungi in ... 633

Fol's method of cultivation 788

Food, bacteria in 716

— ptomaines in 572

— transport by 740

Form of the fungi, variations in, as the

result of degenerative changes 676
Form of the lower fungi, variations

in, during development ... 67t
Formate of lime, fermentation of ... 60;
Formic acid, action on spores ... 66i

Foul brood, bacillus of 34i

Fowl scab, fungus of

Fractional cultivation 80:

Frank on disinfection with bromine 67(
A. Fraenkel's bacillus of pneumonia 325
E. Fraenkel on a diplococcus from

vaginal secretion ... ... 230

Freire on micro-organisms in yellow

fever 203

Friedlander's pneumonia bacteria ... 25c

Fuchsine 78

Fumago •••

Function of the lower fungi in nature 49
Functional activity of the lower fungi 54
Fungi, absorption and assimilation of

nutriment by 54

— alterations which the nutrient

materials undergo

— assimilation of carbon by ... 5-1

— assimilation of nitrogen by ... 54

PAGE
Fungi, conditions affecting the death

of 647

— functional activity of 548

— moiphology of 103

— place of, in the vegetable king-

dom 101

— products of tissue change of ... 559

— spore formation in 105

— tissue change and development

of energy in ... 541

— vital actions of 540

^usisporium solani ... 113

G.

Gadinine 569

Gaff ky on micrococcus tetragenus ... 205

— on typhoid bacilli 248

Gartner and Plagge on the action of

carbolic acid on bacteria ... 668
Gastric juice, action of, on bacteria... 724
Gastro-enteritis, bacteria of ... ... 330

Gemmae 105

General prophylactic measures ... 770

Gentian violet 782

Germ theory, development of ... 70

objections to 81

Germination of spores of bacteria ... 163

of yeast 524

Giant cells and tubercle bacilli ... 263
Glanders, bacillus of 277

— sources of infection of 737

Glucose, forms of, suitable for alco-
holic fermentation 588

Glucosides, ferments of 580

Glycerinate of lime, fermentation of 604

Glycerine, action on spores 666

Glycerine, fermentations of 602

Gonorrhoea, micrococcus of 198

— sources of infection of 736

Goodsir on sarcina ventriculi ... 226
Gbttingen, regulation for disinfec-
tion in 776

Gram's method of staining ... ... 784

Granuloma f ungoides, streptococci in 204
Granulose in the fission fungi ... 527
Grawitz on the development of
pathogenic properties in mould

fungi 138

Ground water as an index of the

moisture of the soil 707

H.

Habitat of bacteria 685

Habitats for bacteria in water ... 715
Haemophilia neonatorum, micro-

• • OAO

cocci in *v6

Hallier 94

Haplococcus reticulatus 1

Hauser's putrefactive bacilli ... 380
Haustoria 104

818

INDEX.

85

680
636

PAGE

Hay bacillus 394

Healthy body, absence of bacteiia in

the 726

Heat, production of, by the lower fungi 558
Henle's views on contagia ... ... 91

Hereditary variations in the lower

fungi, mode of origin of ... 673
Hesse's method of examining air for

bacteria ... ... ... 805

Hoppe-Seyler on the influence of

oxygen on putrefaction ... 533
Hueppe on spores in comma bacilli... 428

— on the production of invertine

ferment by the bacillus lactis 578

— on the staining of spores

— on variability in the lactic acid

bacilli

Hyacinths, yellow disease of...

Hydrochloric acid, action on spores 667
as an inhibitory agent ... 653

Hydrocyanic acid as an inhibitory

agent 653

Hydrogen, role of nascent, in putre-
faction ... 615

Hypha; 104

I.

Illumination of specimens, method of 786

Immunity 752

Indirect transport of infective agents 741

Individual predisposition 748

Infants, bacilli in faeces of 334

Infection as the result of profession

and occupation ... ... 722

— by clothing 719

— by doctors, &c 722

— in children 722

— in cholera 442

— sources of 729

Infective agents, accidents influenc

ing the spread of 768

mode of transport of ... 739

multiplication of, on sur-
rounding objects 731

seats of invasion of 741

slight importance of sapro-

phytic growth of, for the spread

of disease ... 731

Infective diseases, local and seasonal

predisposition to ... ... 761

mode of spread of 728

prophylactic measures against 770

Infective nature of soil ... ... 694

Influenza, micrococci in 203

Inhibition of growth of bacteria ... 648
Inhibitory action of the products of

tissue change ... 566

Injury in relation to infection ... 751
Iodine, action on spores ... ... 666

— as an inhibitory agent 653

Iodine water, ar-tion on spores ... 667

PAttH

Insects, parasitic mould fungi in ... 633

— transport by ... ... ... 740

Intestine, bacteria in the ... 417, 724
Intestinal mucous membrane, pas-
sage of bacteria through ... 742

Intramolecular respiration m the

lower fungi ... ... ... 542

relation of oxygen to ... 542

Invasion, differences in the charac-
ters of the points of 749

Invasion of infective agents, seats of 741

Invertine ... ... ... ... 577

— chemical composition of ... 581

— production of, by bacillus lactis 578
Involution forms of cholera bacilli... 426

J.
Jequirity ophthalmia, bacilli of ... 346

K.

Kephyr, chemical composition of ... 608

— ferment of 372

— preparation of ... 607

Key for the diagnosis of the bacilli... 411

— for the diagnosis of micrococci 232

— for the diagnosis of the spirilla 485
Kitt on protective inoculation ... 756
Klebs on fractional cultivation ... 801
Klebs and Tommasi-Crudeli on bacilli

in malaria 294

Koch, experiments on the inhibitory

action of various poisons ... 653

— on cholera bacilli ... ... 415

— on protective inoculation in

anthrax...

— on spore formation in anthrax

bacilli

— on the advantages of solid

nutrient substrata

— on tubercle bacilli

Koch and Wolff hiigel on sulphurous

acid as a disinfectant...
Konig on disinfection with sublimate 671
Kreibohm's bacilli of saliva ... ... 319

Kurth on bacterium Zopfii 405

758
538

796

260

669

L.

Laboulbenia ... ... ... ... 115

Lactate, of lime, fermentation of ... 604

Lactic acid bacteria ... 363

Lactic fermentation ... ... ... 596

fermentative agents of ... 59(5

materials necessary for ... 596

— nature of the decomposition 596
Lankester on a peach-colouied bac-
terium ... ... ... ... 490

Laveran on organisms in malaria ... 295

Leprosy, bacillus of 2/t

Leptothrix 156

— bueealis .. .. 391

INDEX.

819

Leptothrix gigantea
Leube's bacillus ureae

PAGE PAGE

... 392 Methylene blue 782

... 390 Methyl green 782

— micrococcus ureas 212 — violet 782

Leuconostoc mesenterioides 214 Metschnikoff on phagocytosis ... 643

Liborius on bacteria in relation to Mice, progressive necrosis of tissue in 209

oxygen 531 Micrococci, characters of 171

Lichen ruber, organisms in 297 — analysis of 526

Liebig's views on fermentation ... 86 — key for the diagnosis of ... 232

Light, development of , by the fungi 559 — of putrefaction 217

— influence of , on bacteria ... 535 — pathogenic in man 183

— influence of , on the motility of Micrococcus 155

bacteria 558 — albicans amplus 229

Linen, disinfection of 772 — aurantiacus ... 224

Liver, acute yellow atrophy of micro- — candicans 218

cocci in ... • 203 — cereus albus 228

Local differences in the number of flavus 228

air germs 689 — chlorinus 224

in the number of bacteria in — cinnabareus 218

food 717 — citreus conglomerate 228

Local predisposition to infective — coronatus 220

diseases 761 — cyaneus 224

Localistic view of cholera 467 — flavus desidens 222

Lochia, cocci in ... 200 liquefaciens 219

Loeffler on diphtheria in calves ... 328 tardigradus 219

— on streptococci in diphtheria ... 283 — foetidus 216

— on streptococcus articulorum ... 194 products of 612

Loeffler's bacillus of diphtheria ...280 — f ulvus 225

— bacillus of pigeon diphtheria ... 326 — gonorrhoea 198

— universal staining fluid ... 782 — hasmatodes 225

Loeffler and Schiitz on glanders bacilli 277 — lacteus faviformis 229

Loss of fermentative and pathogenic — luteus 224

properties 565 — Pfliigeri 216

Lower fungi, conditions of life of ... 501 — prodigiosus 352

Lungs, passage of bacteria through... 742 — pyogenes tenuis 189

Lustgarten on the bacilli of syphilis 289 — radiatus ... 221

— roseus 229

— subflavus 200

— tetragenus 205

292 —ureas 212

739 liquefaciens 213

604 nutrient materials necessary

242 for 529

247 — versicolor 222

— violaceus ... 224

603 — viscosus 216

294 — -viticulosus 223

Micro-organisms as parasitic exciting

295 agents of disease 90

— classification of 101

787 Microscopical examination, mode of

202 obtaining the specimens ...778

Microscopical examination of speci-
792 mens 785

Microscopical examination of the

535 lower fungi, methods of ...777

160 Milk, viscous fermentation of ... 599

455 Miller on curved bacilli in carious

797 teeth 476

785 Miller's bacillus, products of ...612

777 — bacteria from the deposit on

teeth 393

777 — coccus from carious teeth ... 230

M.

Malaria, bacteria in

— sources of infection of ...
Malate of lime, fermentation of
Malignant oadema, bacillus of

in man

Mannite fermentation — see viscous.

— fermentation of

Marchiafava on bacilli in malaria ...
Marchiafava and Celli en organisms

in malaria

Marsh gas fermentation — see cellulose.

Mastzellen

Measles, micrococci in

Meat infusion, preparation of, for

cultivations

Mechanical movement, influence of,

on bacteria

Merismopedia

Meteorological influences in cholera
Method of isolating bacteria

— of staining spores

Methods of investigating bacteria ...
Methods of the microscopical ex-
amination of the lower fungi

820

INDEX.

PAGE

Mineral substances, assimilation of,

by the lower fungi ... ... 547

Miguel's experiments on disinfection 652

— method of examining air for

bacteria 804

Mitscherlich's analysis of the ashes

of yeast 518

Mode of spread of the infective

diseases 728

Mode of entrance of bacteria i nto wells 713

Monadina ... ... 143

Monas Okenii '... 494

— vinosa 494

— Warmingii 494

Morphological differences in the

lower fungi 675

Morphology of micro-organisms ... 101
Motility of bacteria, influence of

lighten 558

influence of nutrient

materials on 558

influence of oxygen on 531, 558

influence of temperature on 558

Mould fungi as exciting agents of

disease 629

as parasites in birds ... 634

in fish 634

in insects 633

in man... ... ... 634

on animals ... ... 633

chemical composition of ... 502

concurrence with other

organisms 513

conditions of life of 502

conditions of spore forma-
tion and spore germination ... 514

duration of the vitality of

the spores ... ... ... 515

fermentation of sugar by ... 589

fermentative action of ... 511

growth in the animal body... 508

mode of penetration into

plants 629

nutrient materials of ... 503

relation of, to oxygen . . . 508

relation to concentration of

nutrient material 509

relation to temperature ... 512

relation to the reaction of the

nutrient material 511

Mouldiness 617

Mouse septicaemia, bacillus of ... 310
Mouth, bacteria in ... ... ... 723

Mucor corymbifer 134

— melittophtorus ... 133

— mncedo 131

— racemosus ... 133

— rhizopodiformis 133

— stolonifer 133

Mucorinese ... ... 131

Multiplication of pathogenic bac-
teria in the soil .. 698

PAGE

Muscardine 115

Muscarine ... 571

Musculus's ferment of urine 214, 580
Mussels, poisoning by ... ... 573

Mutability of bacteria, Niigeli's views

on ... 680

— of the characters of the fungi... 672

Mycelium 104

Mycetozoa 142

— parasitic 144

Mycoderma aceti 389

M y conostoc gregarium 492

Mycosis fungoides, streptococci in ... 204

My co-protein 525

Myco-protein in yeast 517

Mydalem 571

Mytilotoxine 573

Myxomycetes 142

N.

Nageli on mineral substances in

relation to the lower fungi ... 548

— on the assimilation of carbon by

the lower fungi 546

— on the self -fermentation of yeast 593
Nageli's analysis of anthrax bacilli... 526

— analysis of yeast ... 516

— experiments on the nutrient

materials of the mould fungi 504

— normal nutrient solutions ... 790

— theory of fermentation 626

— views as to the mutability of

bacteria 680

Natural means of disinfection ... 685
Neisser on the coccus of gonorrhoea 198
Nencki on ptomaines ... ... 568

Nencki's analysis of bacteria ... 525

— my co-protein ... 525

Neuridine 569

Neurine 570

Nicati & Rietsch on the artificial

production of cholera in

animals 436

Nicolaier on the tetanus bacillus ... 340
Nitrates, reduction of, by bacteria ... 528

Nitrification ... 695

Nitrogen, assimilation of, by the lower

fungi 547

— sources of, for the fission fungi 527

— sources of, for yeast 519

— source of supply for the mould

fungi 504

Nitrogenous plastic materials, altera-
tions in by the lower fungi ... 549
Non-contagious facultative parasites 734

— infective diseases 730

Non-hereditary variations in the

lower fungi 673

Non-nitrogenous plastic materials ... 552
Nosema bombycis 208

INDEX.

821

PAGE

Number of air germs, local differ-
ences in the ... 689

Nutrient jelly, preparation of, for

cultivations ... 792

— materials of the budding fungi 518

of the fission fungi 527

of the lower fungi, altera-
tions which they undergo ... 548

of the mould fungi 503

— substrata 789

Nutriment of the lower fungi, amount

required 557

Nutritive requirements of the fungi,

Pasteur on .. 498

Obermeier's spirillum 479

Obligatory aerobes ... 533

— anaerobes 532

— parasites 628

— saprophytes ,.. 629

Occnrrence of bacteria in the air ... 687

iu. the soil 691

in water 711

Oidium albicans 131

— lactis 127

— Tuckeri 127

Oil immersion lenses ... 785

— of cloves as an inhibitory agent 653

— of mustard as an inhibitory

agent 653

— of peppermint as an inhibitory

agent ' 653

— of turpentine as an inhibitory

agent 653

Oogonium 107

Oospores 107

Ophidomonas sanguinea 484

Origin of air germs 687

Osmic acid, action on spores ... 667

Oxygen, influence of, on fermentation 595

— influence of, on the motility of

bacteria 531, 558

— influence of, on the putrefactive

process 614

— influence of, on yeast cells ... 520

— in relation to intramolecular

respiration ... 542

— in relation to the mould fungi... 508

— in relation to the tissue change

of the lower fungi 553

— relation of, to bacteria 530

Ozaena, micrococci in 203

P.

Pancreatic ferment, chemical compo-
sition of 582

Parasitic bacteria 636

— degrees of pathogenic action 637

fate of 686

modes of action of .. .. 638

PAGE

Parasitic bacteria, modes of develop-
ment in the body 638

— fungi 109

classification of 628

— mould fungi 629

— role of micro-organisms, proof of 98

— yeast fungi 636

Parasitismus of the lower fungi ... 627

Parrots, disease of 207

Passet's pseudopneumonia bacteria... 324
Pasteur on acetic fermentation ... 619

— on aerobes and anaerobes ... 530

— on attenuation of chicken
cholera bacilli 317

— on fermentation by yeast ... 77

— on protective inoculation against

anthrax 756

— on protective inoculation for

rabies 758

— on silk- worm disease 209

— on the attenuation of the virus

of rabies 660

— on the fermentation of glucose 590

— on the nutritive requirements

of the fungi 498

Pasteur's bacillus of saliva 321

— flasks for cultivations 788

— nutrient solution 790

— views on putrefaction 614

— views on the attenuation of

anthrax bacilli 658

Pathogenic bacteria, behaviour of, in

water 712

biological peculiarities of ... 641

in the soil, behaviour of ... 698

resistance against excretion 642

resistance against oxygen ... 642

resistance to the living cells . 643

Pathogenic organisms, attenuation of 656

— — fermentation of carbo-hy-

drates by 601

Peach-coloured bacterium, Lankester

on 490

Pebrine, micro-organisms in 208

Penicillium 136

— glaucum 137

Pepsine, chemical composition of ... 581
Peptone, production of, by yeast ... 549

Peptonising ferments 578

Peptotoxine 570

Perisporiaceae 118

Perithecia 106

Permanganate of potash, action on

spores 667

as an inhibitory agent ... 653

Peronospora infestans 112

Peronosporeae 112

Pettenkofer on the relation between

the soil and infective bacteria 692
Pfeffer on certain nutrient materials

in relation to the movement of

bacteria 558

Phago-cytosis 643

822

INDEX.

PAGE

Phosphorus, source of, in the fungi... 547

Photography of bacteria 787

Phragmidiothrix multiseptata ... 491
Phthisical sputa, distribution of the

bacilli by means of 271

Phycomycetes 109

Physiological differences between the

lower fungi 678

Pig typhoid, bacillus of 302

Pigeon diphtheria, bacillus of ... 326
Pigment, chemical nature of ... 562

— formation, relation of oxygen to 562
relation of the nutrient sub-
stratum to 562

— forming micrococci ... ... 224

— production of, by the lower fungi 561

Pink yeast 154

Pityriasis versicolor ... 127

Plants, epidemic disease of 631

— parasitic bacteria in 636

Plasma cells 787

Plasmiodophora Brassicae ... ... 144

Plasmodia 142

Plate cultivations 797

Pleuropneumonia in cattle, micro-
organisms in 204

Pneumonia, bacillus of (Friedlander) 255

— bacilli (Friedlaender) analysis of 526

— bacteria, bacilli resembling ... 322

— Fraenkel's bacillus of 325

Potash soap, action on spores ... 666

as an inhibitory agent ... 653

Potato bacilli 399

— disease 112

Potatoes,preparationof,forcultivations 792
Predisposition, role of, in tuberculosis 273

— to infection in different species

and individuals 748

Preservation of pathogenic bacteria

in the soil 701

in the soil not necessary

for the spread of disease ... 704
Products of the putrefactive fermen-
tation 610

— of the tissue change of the lower

fungi 559

Progressive abscess formation in rab-
bits, micrococcus of ... ... 210

— gangrenous emphysema in man 247

— necrosis of tissue in mice, micro-

coccus of 209

Promycelium 110

Prophylactic measures against the

spread of infective diseases ... 770

— regulations against cholera ... 470
Protective inoculation ... ... 752

general value of 760

in anthrax ... ... ... 240

in Kauschbrand 300

in swine erysipelas 306

Proteus mirabilis 382

— vulgaris 380

PAGE

Proteus vulgaris and mirabilis, pro-
ducts of ... ... ... 612

— Zenkeri 385

Protospores 108

Ptomaines 567

— action of 638

— hygienic importance of ... 572

— in food 572

— influence of nutriment on the

formation of ... ... ... 574

— influence of, on parasitismus ... 645

— of putrefaction 569

— of typhoid bacilli 571

— production of, by the lower fungi 561
Puccinia graminis ... ... ...116

Putrefaction 608

— micrococci of ... 217

— spontaneous ... ... ... 613

Putrefactive anaerobes 385

— bacteria 375

— fermentation, materials for ... 609
multiplicity of the exciting

agents of 611

nature of the decomposition 609

products of ... 610

variations in 611

— process, influence of oxygen on 614

— ptomaines 569

Putrescine 569

Putrid intoxication, ptomaines as the

cause of 573

Pyaemia in rabbits, micrococcus of ... 210

Pycnida 106

Pyocyanine ... 356

— chemical composition of ... 562
Pyrenomycetes 113

Q.

Quantitative estimation of the tissue

change ... 556

Quercite, fermentation of 603

Quinate of lime, fermentation of ... 605
Quinine, action on spores 667

— as an inhibitory agent 654

K.

Babbits, progressive abscess forma-
tion in 210

— pyaemia in 210

— septicaemia in 211

— septicaemia, bacillus of 312

Rabies, attenuation of the virus of... 660

— protective inoculation for ... 758

— sources of infection of 736

Rasmussen's species of leptothrix ... 392

Ratimoff on disinfection 652

Raulin's experiments on the nutrient

materials of the mould fungi 503

Rauschbrancl, bacillus of 299

Reaction of the nutrient material in

relation to the yeast fungi ... 521

INDEX.

823

PAGE

Reaction of the nutrient material in

relation to bacteria ... ... 534

Relapsing diseases ... 752

Relapsing fever, spirillum of ... 479

Rennet, ferment of ... ... ... 79

Respiratory mucous membrane, bac-
teria on 724

Rhabdomonas rosea ... 494

Rhinoscleroma, bacillus of ... ... 291

Ribbert on bacteria in healthy in-
testinal mucous membrane ... 743
Richet's experiments on disinfection 654
Rinderpest, micro-organisms in ... 204
Rindfleisch on streptococci in mycosis

fungoides 209

Rouget du pore, bacillus of 302

Rust ,. 116

Saccharomyces albicans ... ... 152

— apiculatus ... 150

— cerevisiae 148

— conglomerate ... 150

— ellipsoideus ... 150

as the ferment of wine ... 589

— cxiguus 150

— glutinis ... ... ... ... 154

— mycoderma ... 150

— Pastoriarius 150

— sphasricus 150

Salicylic acid, action on spores ... 666

as an inhibitory agent ... 653

Saliva, spirochrete of ... " 482

Salt solution, action on spores ... 666

Saprine 569

Saprolegnia 634

Saprophytic bacilli ... 351

— micrococci 212

— mould fungi, results of injection

in animals ... 634

Sarcina 160

— aurantiaca ... ... ... 226

— intestinalis ... ... ... 227

— litoralis Reitenbachii hyalina... 228

— lutea .' 225

— ventriculi 226

Sattler on jequirity bacilli 347

— on micro-organisms in trachoma 203
Scarlatina, micrococci in 202

— epidemics, local variations in ... 764

Schizomycetes 155

Sehou's bacillus pneumonicus agilis... 325

Schroeder and Dusch... 72

Schulze ... 71

Schiitte, regulations for disinfection

in Gb'ttingen 776

Schwann ... 70

Sclerotium 104

Season and locality in relation to the

epidemic diseases of plants ... 631
Season, influence of. in cholera ... 453

PAGE

Seasonal differences in the number

of bacteria in food 718

Seasonal predisposition to infective

diseases 761

Seats of invasion of infective agents 741

Sections, method of preparation and

779
802
801
310
312
211
450

staining of
Separation of bacteria by dilution

in fluid substrata

Septicasmia in mice, bacillus of

— in rabbits, bacillus of ...
micrococcus of ...

Ships,. cholera on

Sieber's analysis of the mould fungi 502
Significance of micro-organisms ... 66

Silk-worms, lethargy of 207

Skin, bacteria on 723

Small-pox epidemics, seasonal varia-
tions in 763

Smut 110

Soil, bacteriological investigation of

693, 809

— influence of, in cholera 457

— occurrence and behaviour of

bacteria in 691

— preservation of pathogenic bac-

teria in 701

— relation to infective bacteria ... 692

— transport of bacteria within the 695
Solid nutrient substrata, advantages

of 795

Sources of infection 729

Special methods of cultivation

Special prophylactic measures in indi
vidual diseases...

Specific points of invasion, impor-
tance of, for the mode of spread
of the disease

Spermogonia

Sphaerotilus natans

Spirira

— characters of ...

— key for the diagnosis of
Spirillum

— choleras Asiatics

— Finkler and Prior

— leucomelsenum

— Obermeieri

794
.. 771

747
106
493
415
174
485
156
415
472
484
479

— rugula 482

— sanguineum

— serpens

— sputigenum

— tenue

— tyrogenum

— undula

— volutans
Spirochaete

— denticola

— Obermeieri

— plicatilis
Spiromonas

— Cohnu

484
483
478
483
477
483
483
156

479
481
493
493

824

INDEX.

PAGE

Spiromonas volubilis 493

Spirulina 156, 380

Spontaneous putrefaction ... ... 613

Sporangium ... ... 106

Spore formation in bacteria, condi-
tions of 587

in the mould fungi 514

in yeast 524

Spore germination in bacteria, condi-
tions of 539

in the mould fungi ... ... 514

in yeast ... -524

Spores, formation of 342

— method of staining 785

— of bacteria, destruction of ... 663

— of fungi, acrogenous segmenta-

tion of 105

endogenous, formation of 106

intercalary, formation of 105

sexual fructification of ... 106

Spores of mould fungi, duration of

the vitality of 515

Spores, resistance of, to high tem-
peratures 663

Staining materials for bacteria ... 780

— of bacteria 778

Staphylococcus ... 156

— pyogenes albus 187

characters of ... ... 187

effect on animals. 188

— pyogenes aureus ... ... 183

action on animals ... 185

mode of growth 184

morphology of ... ... 183

occurrence in man ... 186

products of growth 185, 571

• — citreus ... 188

Steam, apparatus for disinfection by 772

— as a disinfecting agent -. 665

Sterigmata ... ... ... ... 105

Sterigmatocystis 121

Sterilisation of vessels and nutrient

substrata 791

Stomach, bacteria in ... ... ... 724

Streptococci in diphtheria. Loeffler on 283

— distinction between the ... 196
Streptococcus 155

— articulorum ... 194

— bombycis... ... ... ... 207

— Charrin 207

— erysipelatosus 191

action on animals ... ... 192

mode of growth 191

occurrence in man ... ... 192

— malignus ... 193

— perniciosus psittacorum ... 207

— pyogenes 189

action on animals 190

modeof growth 189

morphology of 189

— occurrence in man ... ... 191

Streptococcus septicus 195

PAGE

Streptothrix Foersteri 493

Stutzer's analysis of yeast 517

— analysis of the mould fungi ... 503
Sugar, alcoholic fermentation of, by

yeast 588

— influence of the amount of, on

fermentation ... 594

Sulphate of copper, action on spores 667

Sulphur in the beggiatoa 527

Sulphuretted hydrogen, action on

spores 667

Sulphuric acid, action on spores ... 667
Sulphurous acid as a disinfectant ... 668

Sweat, red 225

Swine erysipelas, attenuation of the

bacilli of 660

bacillus of 302

micrococci in ... 205

Swine fever, protective inoculation

against 756

Symptomatic anthrax, attenuation of

the bacilli of 660

protective inoculation against 756

Syphilis, bacillus of 288

— sources of infection of ... ... 736

T.

Tappeiner on cellulose fermentation 600
Tartrate of lime, fermentation of ... 604
Teeth, caries of, bacilli in 298

— Miller's curved bacilli in ... 476
Ideological role of the lower fungi 496
Temperature in relation to the growth

of bacteria 650

— in relation to the mould fungi 512

— influence of, on fermentation ... 594

— influence of, on the motility of

bacteria ... ... ... 558

— relation of, to bacteria ... ... 536

— relation to yeast 522

— resistance of bacteria to ... 663
Test for trustworthy disinfecting

media 666

Tetanus bacillus ... 340

Thallus 104

Thrush, fungus of 131, 152

Thymol, action on spores 66(5

— as an inhibitory agent 653

Tilletia caries 110

Tinea tonsurans, fungus of ... ... 127

Tissue change in presence of oxygen 553

in the lower fungi 541

of the lower fungi, products of 559

when oxygen is absent ... 554

Toxic effects of cholera cultivations 440

Trachoma, micrococci in 203

Transmission of infective diseases

from the sick to the healthy... 729

Transport by air, conditions for ... 741

influence of , on contagiousness 740

INDEX.

825

PAGE

Transport of bacteria 687

in the soil by downward

currents of water 696

within the soil 695

— of infective agents to indi-

viduals, mode of ... • ... 739

— of preserved bacteria from the

soil to the man 705

True fungi, classification of 108

Tubercle bacillus 260

method of staining of ...783

mode of entrance into the

body 272

Tuberculosis, mode of spread of ... 271

— sources of infection of 737

Turpentine, oil of, action on

spores 667

Typhoid bacilli, distribution from

the soil 710

fermentation of carbo-hy-
drates by 601

modes of distribution of ... 253

points of entrance of ... 253

Typhoid fever, bacillus of 248

contagiousness of 734

local and seasonal variations

in 765

sources of infection of ...738

Tyrothrix 606

U.

Unboiled tissues, preservation of ... 74

Urea ferment 580

Uredinese i 116

Ustilagineae 109

Ustilago carbo... 110

V.

Vaccination 755

Vaccinia, micrococci in 202

Vandevelde's analysis of bacillus

subtilis 526

Variations in the lower fungi ... 681

— in the form of the fungi as the

result of degenerative changes 676

— in the form of the lower fungi

during development 675

— in the lower fungi, relation to

external conditions 674

— in the products of tissue change

as the result of varying ex-
ternal conditions 679

Variola, micrococci in 202

Various anaerobes, products of ... 612
Vessels for the cultivation of organ-
isms 788

Vibrio 156

— rugula 482

Vibrion septique 242

Villemin on the inoculation of

tubercle ... .. 260

PAGE

Vinegar plant, analysis of ... ... 526

Violet bacillus 361

Viscose ... 216, 599

Viscous fermentation 598

of milk 599

of wine ... 598

Vital actions of the lower fungi ... 540

Von Pettenkofer's views on cholera... 468

Von Sehlen on organisms in malaria 295

W.

Water, bacteriological investigation of 807

— influence of, in cholera 458

— occurrence of bacteria in ... 711

— transport by 740

Weight of air germs 688

Whooping-cough, organisms in ... 297
Winds, influence of dry winds on the

number of air germs 690

Wine, viscous fermentation of ... 598
Wortmann on diastatic ferment ... 577
Wyssokowitsch on the destruction of

bacteria in the body 644

— on the passability of the walls

of the lungs and intestine by
bacteria 743

X.

Xerosis conjunctivas, organisms in ... 297

Y.

Yeast, alcoholic fermentation of sugar

by 588

— concurrent growth with other

fungi 522

— discovery by Caignard-Latour 69

— forms of, capable of exciting f er

mentation 588

— influence of fermentative acti

vity on the growth of .. 522

— influence of quantity of, on fer

mentation 594

— myco-protein in 517

— necessity for oxygen 520

Yeast of beer 149

— relation of temperature to ... 522

— relation of, to the fermentative

process 76

— relation to atmospheric pressure 521

— self -fermentation of 592

— spore germination 524

— spores of 524

— the only cause of alcoholic fer-

mentation 71

Yeast fungi, characters of 146

formation of mycelium by ... 147

formation of spores in ... 147

multiplication of 147

relation to concentration of

nutriment .. 520

826

INDEX.

PAGE

Yeast fungi, relation to the reaction

of the nutriment 521

Yellow fever, micrococci in ... ... 203

organisms in 297

Z.

Zooglaea

164

PA(IE

Zooglaea ramigera 492

Zoonotic finger erysipeloid, micro-
cocci in ... 201

Zopf on crenothrix Kiihniana ... 486
Zopf's classification of bacteria,

objections to 181

Zygomycetes 109

Zygospores ... ... 107

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