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THE  INTERNATIONAL  SCIENTIFIC  SERIES 
VOLUME  LVI 


THE 

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T 


TOE  INTERNATIONAL  SCIENTIFIC  SERIES 


MICROBES 


FERMENTS   AND  MOULDS 


BY 


E.    L.    TROUESSART 


WITH  ONE  HUNDRED  AND  SEVEN  ILLUSTRATIONS 


NEW  YORK 
D.    APPLETON    AND    COMPANY 

1,  8,  AMD  5  BOND  STREET 

1890 


PKEFACE. 


THE  number  of  works  which  treat  of  microbes  is 
already  considerable,  but  they  have  all  been  written 
for  a  special  public  of  physicians  or  naturalists,  and 
imply  that  the  reader  is  familiar  with  the  ideas 
already  established  on  pathology  or  on  cryptogamic 
botany. 

Although  the  science  of  microbes  is  of  recent 
origin,  it  has  made  immense  progress  in  the  course  of 
a  few  years.  It  is,  moreover,  essentially  a  French 
science,  since  it  is  owing  to  Pasteur's  admirable 
labours,  as  well  as  to  his  solid  genius,  aided  by  the 
faith  and  energy  of  his  disciples,  that  this  science 
has  been  able  to  overcome  the  prejudices  of  ages,  and 
to  penetrate  into  the  very  heart  of  the  ancient  theory 
of  medicine,  so  as  to  transform  and  regenerate  it. 

Every  one  now  speaks  of  microbes,  yet  few  of  those 
who  make  use  of  the  term  have  any  clear  conception 


Vi  PEEFACE. 

of  the  beings  in  question,  or  could  give  an  exact 
account  of  the  function  which  microbes  fulfil  in 
nature.  And  yet  this  function  concerns  us  all. 

The  man  -of  the  world  who  desires  to  take  part  in 
a  scientific  discussion ;  the  lawyer  who  has  to  treat  of 
a  question  of  hygiene  in  the  presence  of  experts ;  the 
engineer,  the  architect,  the  manufacturer,  the  agricul- 
turist, the  administrator — all  have  to  consider  such 
questions,  and  they  will  find  in  this  work  clear  and 
precise  notions  on  microbes,  notions  which  they  would 
find  it  difficult  to  glean  from  books  designed  for 
physicians  and  professional  botanists. 

The  questions  of  practical  hygiene,  those  which 
concern  domestic  economy,  agriculture,  and  manufac- 
tures, and  which  are  connected  with  the  study  of 
microbes,  must  especially  demand  attention.  These 
are  pertinent  questions  in  such  a  book  as  this.  There 
is  a  certain  danger  in  vulgarizing  notions  of  medicine, 
strictly  so  called;  but  it  can  only  be  beneficial  to 
make  every  one  acquainted  with  the  precepts  of  hy- 
giene, which  cannot  become  popular  until  they  have 
penetrated  into  the  habits  and  routine  of  national 
life. 

There  is  much  to  be  done  before  modern  society 
is  practically  on  a  level  with  the  achievements  of 
science;  many  prejudices  must  be  uprooted,  and  many 


PREFACE.  Vil 

false  notions  must  be  replaced  by  those  which  are 
sounder  and  more  just. 

For  this  reason,  we  have  endeavoured  to  make 
this  work  intelligible  to  all  It  may  be  read  with 
profit  by  those  who  possess  the  elementary  notions 
of  natural  science  which  are  included  in  the  course 
of  primary  instruction.  We  therefore  hope  that  the 
volume  may  find  a  place  in  the  libraries  of  secondary 
instruction,  and  in  public  libraries. 

Although  the  work  is  not  specially  intended  for 
physicians,  yet  practical  men  may  not  be  indisposed 
to  glance  at  it :  it  may,  at  any  rate,  serve  as  an  intro- 
duction to  the  much  more  learned  works  of  Cornil 
and  Babes,  of  Duclaux,  Klein,  Koch,  Sternberg,  etc. 
We  have  given  an  important  place  to  the  botanical 
question,  which  is  too  often  neglected  in  works  on 
microbian  pathology.  From  this  point  of  view,  the 
narrow  bond  which  connects  bacteria  with  ferments 
and  moulds  has  to  some  extent  marked  out  the  plan 
we  have  adopted;  namely,  that  of  passing  from  the 
known  to  the  unknown,  from  what  is  visible  with  the 
naked  eye  to  that  which  is  only  visible  with  the  aid 
of  the  microscope. 

ANGERS,  September  10,  1885. 


TABLE   OF   CONTENTS. 


INTRODUCTION. 

FAGB 

MICROBES  AND  PROTISTA  ...  ...  ...  ...  ...        1 


CHAPTER  L 

PARASITIC  FUNGI  AND  MOULDS       ...           ...           ...           ...  9 

I.  General  remarks  on  fungi              ...            ...            ...  9 

II.  Basidiomycetes :  uredinese,  the  rust  of  wheat  and  grasses  14 

I 1 1.  Ascomycetes :  ergot  of  rye ;  mould  of  leather  and  dried  fruit  20 

IV.  Oomycetes,  mucorineae,  or  moulds,  strictly  so  called  ;  pero- 

nosporaa;  potato-fungus             ...             ...            ...  27 

V.  Parasitic  fungi  of  the  vine :  oidium,  mildew,  etc.             ...  32 

VI.  Habitat  and  station  of  parasitic  fungi :  their  destructive 

action            ...            ...            ...            ...            ...  43 

VII.  Parasitic  fungi  of  insects,  considered  as  auxiliaries  to  man  47 

VIII.  Muscardin,  or  disease  of  silkworms      ...            ...            ...  50 

IX.  Parasitic  fungi  of  the  skin  and  mucous  membrane  of  man 

and  other  animals      ...            ...            ...            ...  51 

CHAPTER  IL 

FERMENTS  AND  ARTIFICIAL  FERMENTATIONS               ...           ...  60 

I.  Definition  of  fermentation...            ...            ...            ...  66 

II.  Vegetable  nature  of  ferments,  or  yeasts  ...            ...            ...  72 

III.  Ferments  of  wine;  alcoholic  fermentation     ...            ...  74 

IV.  Beer-yeast    ...            ...            ...             ...            ...            ...  78 

V.  Concerning  some  other  fermented  drinks      ...            ...  82 

VL   Yeast  of  bread            84 


X  CONTENTS. 

CHAPTER  III. 

PAGE 

MICROBES,  STRICTLY  so  CALLED,  OR  BACTERIA              ...  ...      85 

I.  The  vegetable  nature  of  microbes               ...  ...              85 

II.  Classification  of  microbes,  or  bacteria  ...             ...  ...      91 

II [.  The  microbe  of  vinegar,  and  acetic  fermentation  ...              95 

IV.  The  microbes  which  produce  the  diseases  of  wine  ...       98 

V.  The  microbe  of  lactic  fermentation               ...  ...            105 

VI.  The  ammoniacal  fermentation  of  urine               ...  ...     107 

VII.  Butyric  fermentation  of  butter,  cheese,  and  milk  ...             109 

VIII.  Putrid  fermentation,  game-flavour       ...             ...  ...     112 

IX.  Aerobic  and  anaerobic  microbes    ...            ...  ...             117 

X.  The  microbes  of  sulphurous  waters      ...            ...  ...     119 

( XI.  The  microbes  which  produce  saltpetre        ...  ...            121 

XII.  The  microbes  which  destroy  building  materials  ...     323 

XIII.  The  microbes  of  chalk  and  coal     ...            ...  ...            121 

XIV.  Chromogenic  microbes             ...            ...            „.  ...     126 

XV.  The  microbe  of  baldness               ...            ...  131 


CHAPTER  IV. 

THE  MICROBES  or  THE  DISEASES  OF  DOMESTIC  ANIMALS  ...    132 

I.  Anthrax,  or  splenic  fever                ...            ...  ...             132 

II.  Vaccination  for  anthrax          ...            ...            ...  ...     139 

III.  Fowl  cholera    ...            ...            ...            ...  ...            142 

IV.  Swine  fever              ...            ...            ...            ...  ...     143 

V.  Some  other  diseases  peculiar  to  domestic  animals  ...            144 

VI.  Babies       ...            ...            ...            ...            ...  ...     147 

VII.  Glanders       ...                ...             ...             ...  ...            149 

VIH.  Pebrine  and  flacherie,  two  diseases  of  silkworms  ...    150 


CHAPTER   V. 

THE  MICROBES  OF  HUMAN  DISEASES             ...           ...  ...    156 

.1.  Microbes  of  the  air,  the  soil,  and  water     ...  ...            156 

II.  Microbes  of  the  mouth  and  digestive  canal  in  a  healthy 

man      ...             ...             ...             ...             ...  ...     172 

III.  The  virulent  microbe  of  human  saliva       ...  ...            176 

IV.  The  microbes  of  dental  caries               ...            ...  ...     177 

V.  The  microbes  of  intermittent  or  marsh  fevers  ...            179 

VI.  The  microbes  of  recurrent  fever  and  yellow  fever  ...     187 


CONTENTS.  XI 

PAGE 

VII.  Typhoid  fever  and  typhua           191 

VIII.  The  microbe  of  cholera        ...            ...            ...            ...  195 

IX.  Eruptive  fevers  :  scarlatina,  small-pox,  measles,  etc.  209 

X.  The  microbes  of  croup  and  whooping-cough     ...            ...  215 

XI.  The  microbes  of  phthisis  and  leprosy        ...            ...  ±i:; 

XII.  The  microbe  of  pneumonia  ...             ...            ...            ...  2±) 

XIII.  Some  other  diseases  due  to  microbes          ...            ...  230 

XIV.  The  microbe  of  erysipelas    ...             ...            ...            ...  232 

XV.  The  microbes  of  pus,  septicemia,  etc.         ...            ...  234 

XVI.  The  microbes  of  other  diseases,  due  to  wounds                ...  236 

XVII.  The  mode  of  action  of  pathogenic  microbes :  ptomaines  237 

CHAPTER   VI. 

PROTECTION  AGAINST  MICROBES        ...            ...            ...           ...  242 

L  Antiseptic  treatment  of  wounds:   Gue'rin's  protective  treat- 
ment;  Lister's  dressing    ...             ...             ...             ...  242 

II.  Hygiene    of  drinking  -  water :    water    free    from   microbes  ; 

Cuarnberland  filter    ...             ...             ...            ...            ...  245 

CHAPTER  VII. 

LABORATORY  RESEARCH,  AND  CULTURE  OF  MICROBES            ...  258 

CHAPTER  VIII. 

POLYMORPHISM  OF  MICROBES           ...            ...           ...           ...  272 

CHAPTER  IX. 

CONCLUSION  ...            ...            ...            ...            ...           ...  285 

The  Miorobian  Theory  compared  with  other  Theories  set  forth  to 

explain  the  Origin  of  Contagious  Diseases            ...            ...  285 

APPENDIX. 

A.  Terminology  of  Microbes           ...            301 

B.  Micrococcus  of  phosphorescence       ...             ,,,            ,,,  394 

C.  Diseases  of  plants  caused  by  bacteria     ...            ...             ...  305 

D.  Ptomaine  of  the  microbe  of  fowl  cholera         ...             ...  306 

E.  Cesspools.    System  of  conveying  everything  to  the  sewers  306 

F.  Sewers  of  Paris  and  the  Plain  of  Gennevilliers            ...  307 

G.  Useful  microbes          ...            ...             ...            ...               t  393 

H.  Ptomaines  of  lish                 308 

,  300 


X  CONTENTS. 

CHAPTER  III. 

PAGE 

MICROBES,  STRICTLY  so  CALLED,  OR  BACTERIA              ...  ...      85 

I.  The  vegetable  nature  of  microbes               ...  ...              85 

II.  Classificatiou  of  microbes,  or  bacteria  ...             ...  ...      91 

III.  The  microbe  of  vinegar,  and  acetic  fermentation  ...              95 

IV.  The  microbes  which  produce  the  diseases  of  wine  ...       98 
V.  The  microbe  of  lactic  fermentation               ...  ...            105 

VI.  The  ammoniacal  fermentation  of  urine               ...  ...    107 

VII.  Butyric  fermentation  of  butter,  cheese,  and  milk  ...             109 

VIII.  Putrid  fermentation,  game-flavour       ...             ...  ...     112 

IX.  Aerobic  and  anaerobic  microbes    ...            ...  ...             117 

X.  The  microbes  of  sulphurous  waters      ...            ...  ...     119 

,  XL  The  microbes  which  produce  saltpetre        ...  ...            121 

XII.  The  microbes  which  destroy  building  materials  ...     123 

XIII.  The  microbes  of  chalk  and  coal    ...            ...  ...            124 

XIV.  Chrornogenic  microbes             ...            ...            ...  ...     126 

XV.  The  microbe  of  baldness               ...           ...  131 


CHAPTER  IV. 

THE  MICROBES  OF  THE  DISEASES  OF  DOMESTIC  ANIMALS  ...    182 

I.  Anthrax,  or  splenic  fever                ...            ...            ...  132 

II.  Vaccination  for  anthrax          ...            ...            ...  ...     139 

III.  Fowl  cholera    ...            ...            ...            ...            ...  142 

IV.  Swine  fever              ...            ...            ...            ...  ...     143 

V.  Some  other  diseases  peculiar  to  domestic  animals     ...  144 

VI.  Rabies        ...            ...            ...            ...            ...  ...    147 

VII.  Glanders       ...                149 

VIII.  Pebrine  and  flacherie,  two  diseases  of  silkworms  ...    150 


CHAPTER   V. 

THE  MICROBES  OF  HUMAN  DISEASES             ...           ...  ...    156 

J.  Microbes  of  the  air,  the  soil,  and  water     ...  ...            156 

II.  Microbes  of  the  mouth  and  digestive  canal  in  a  healthy 

man      ...             ...             ...             ...            ...  ...     172 

III.  The  virulent  microbe  of  human  saliva       ...  ...            176 

IV.  The  microbes  of  dental  caries               ...            ...  ...     177 

V.  The  microbes  of  intermittent  or  marsh  fevers  ...            179 

VI.  The  microbes  of  recurrent  fever  and  yellow  fever  ...     187 


CONTENTS.  XI 

PAGE 

VII.  Typhoid  fever  and  typhus           ...            ...            ...  191 

VIII.  The  microbe  of  cholera         ...            ...            ...            ...  195 

IX.  Eruptive  fevers  :   scarlatina,  .small-pox,  measles,  etc.  209 

X.  The  microbes  of  croup  and  whooping-cough     ...            ...  215 

XI.  The  microbes  of  phthisis  and  leprosy        ...            ...  ±>:; 

XII.  The  microbe  of  pneumonia  ...            ...            ...            ...  229 

XIII.  Some  other  diseases  due  to  microbes          ,..            ...  230 

XIV.  The  microbe  of  erysipelas    ...             ...            232 

XV.  The  microbes  of  pus,  septiceinia,  etc.         ...            ...  234 

XVI.  The  microbes  of  other  diseases,  due  to  wounds                ...  236 

XVII.  The  mode  of  action  of  pathogenic  microbes :  ptomaines  237 

CHAPTER   VI. 

PROTECTION  AGAINST  MICROBES        ...            ...            ...           ...  242 

L  Antiseptic  treatment  of  wounds :   Guerin's  protective  treat- 
ment ;  Lister's  dressing    ...             ...             ...             ...  242 

II.  Hygiene    of  drinking-water:    water    free    from   microbes; 

Chamberland  filter    ...            ...            ...            ...            ...  245 

CHAPTER   VII. 

LABORATORY  RESEARCH,  AND  CULTURE  or  MICROBES            ...  258 

CHAPTER  VIII. 

POLYMORPHISM  OF  MICROBES           ...            ...           ...           ...  272 

CHAPTER  IX. 

CONCLUSION  ...            ...            ...            ...            ...            ...  285 

The  Miorobian  Theory  compared  with  other  Theories  set  forth  to 

explain  the  Origin  of  Contagious  Diseases            ...            ...  285 

APPENDIX. 

A.  Terminology  of  Microbes           ...            ...            ...            ...  301 

B.  Micrococcus  of  phosphorescence       ...            ...            ...  304 

C.  Diseases  of  plants  caused  by  bacteria     ...            ...             ...  305 

D.  Ptomaine  of  the  microbe  of  fowl  cholera         ...             ...  306 

E.  Cesspools.     System  of  conveying  everything  to  the  sewers  306 

F.  Sewers  of  Paris  and  the  Plain  of  Gennevilliera  307 

G.  Useful  microbes           ...            ...             ...            ...               t  30g 

H.  Ptomaines  of  fish                "  '  308 

INDEX    ,                                                                                        .  _QAQ 


MICROBES,  FERMENTS,  AND  MOULDS, 


INTRODUCTION. 

MICROBES  AND  PROTISTA. 

MICROBES  are  the  most  minute  living  things  which 
the  microscope  permits  us  to  see  distinctly,  so  as  to 
study  their  organization.  They  are  for  the  most  part 
invisible  to  the  naked  eye,  and  even  by  the  aid  of  a 
simple  lens.  In  order  to  form  an  exact  idea  of  their 
forms  and  structure,  we  require  the  strongest  magni- 
fiers of  modern  instruments,  which  enlarge  the  object 
500, 1000,  and  even  1500  diameters. 

The  word  microbe  has  been  recently  introduced 
into  the  French  language ;  it  did  not  exist  eight  years 
ago,  and  for  this  reason  it  will  be  sought  for  in  vain 
in  most  dictionaries.  It  was  under  the  following  cir- 
cumstances that  this  term,  now  in  such  general  use, 
was  invented  by  Sedillot,  an  eminent  surgeon,  whose 
recent  death  is  deplored  by  France. 

Those  naturalists   who    have    studied    the    most 


2  MICROBES,   FERMENTS,  AND  MOULDS. 

minute  living  things  have  at  all  times  been  at  a  loss 
to  decide  whether  they  have  had  to  do  with  animals 
or  plants.  There  can  be  no  such  doubt  when  we  com- 
pare a  tree  of  which  the  roots  are  fastened  in  the  soil 
with  a  quadruped  which  moves  freely  on  its  surface. 
But  these  are  highly  developed  forms,  the  one  in  the 
vegetable,  the  other  in  the  animal  kingdom.  The 
lower  representatives  of  the  two  kingdoms  are,  on 
the  other  hand,  often  so  much  alike  as  to  baffle  the 
most  experienced  naturalist.  The  animals  which  are 
assigned  to  the  order  of  Zoophyta,  or  animal -plants, 
have,  as  the  name  indicates,  a  form  which  led  them  to 
be  for  a  long  while  regarded  as  plants  ;  many  of  them 
are  fastened  to  the  bottom  of  the  sea  or  to  rocks  as  if 
by  actual  roots,  and,  when  superficially  examined,  their 
movements  do  not  differ  much  from  those  which  may 
be  produced  in  true  plants,  as,  for  instance,  in  the 
mimosa. 

Many  of  the  lower  plants,  belonging  to  the  groups 
of  Algse  and  Fungi,  live  in  the  water  without  being 
fixed  by  roots ;  many  are  animated  by  more  or  less 
apparent  motion,  at  any  rate  during  part  of  their 
existence,  so  that  it  is  often  somewhat  difficult  to  dis- 
tinguish them  under  the  microscope  from  those  beings 
which  are  generally  called  Infusoria,  and  which  are 
true  animals. 

Hence  it  follows  that  the  boundary  between  the 
animal  and  vegetable  kingdoms  remains  indefinite, 
and  that  many  of  those  microscopic  organisms  which 


MICROBES  AND  PEOTISTA.  3 

we  have  now  to  consider,  may  be  assigned  indifferently 
to  one  or  the  other  kingdom. 

Bory  de  Saint- Vincent,  a  naturalist  belonging  to 
the  early  part  of  the  century,  and  after  him  Haeckel, 
have  attempted  to  evade  this  difficulty  by  creating 
between  the  animal  and  vegetable  kingdoms  an  inter- 
mediate kingdom,  which  they  have  named  Protista, 
indicating  thereby  that  it  includes  the  first  animals 
which  in  the  geological  ages  appeared  on  the  earth's 
surface.  This  kingdom  of  Protista  includes  the  fol- 
lowing groups,  starting  from  the  simplest  and  going 
on  to  those  which  are  more  complex : — 

*1.  Monera  (or  Microbes,  strictly  so  called ;  Schizotuycetes,  Bac- 
teria, Vil>rioiies,  etc.). 
2.  Amorphous  Rhizopoda  (or  Amcoboj). 
3    Cire^urinidiB. 

4.  Flagellata. 

5.  Cat;. llacla. 
G.  Infusoria. 

7.  Acinetae. 

8.  Labyrinthulaj. 

9.  Diatomaceae. 
*10.  Myxomycetes. 
*11.  Fungi. 

12.  Thalamophora  (Foraminifera  or  Rhizopoda  with  a  calcareous 

Hkdctou). 

13.  Radiolaria  (or  Rhizopoda  with  a  silicious  skeleton). 

The  groups  marked  with  an  asterisk  are  those 
which  we  propose  to  study  in  this  work.  For  the 
most  part,  the  organisms  assigned  to  them  resemble 
plants  in  their  general  characters.  They  are  parasites 
which  derive  their  nutriment  from  other  living  beings. 

For  this  reason,  many  of  these  organisms  are  the 


4  MICROBES,  FERMENTS,  AND  MOULDS. 

cause  of  the  more  or  less  serious  diseases  which  affect 
animals  or  plants.  Naturalists  who  regard  these  para- 
sites as  animals  have  termed  them  Microzoaria  (from 
two  Greek  words  signifying  small  animals).  Those 
who  regard  them  as  plants  have  called  them  Micro- 
phytes (small  plants),  and  it  is  still  disputed  which 
term  is  the  most  applicable  to  them.  In  other  words, 
it  is  still  undecided  whether  they  should  be  classed  in 
the  animal  or  vegetable  kingdom. 

It  was  at  the  Paris  Academy  of  the  Sciences,  on 
the  llth  of  March,  1878,  that  Sedillot  took  part  in  one 
of  the  probably  interminable  discussions  between  the 
advocates  of  the  Microzoaria  and  those  of  the  Micro- 
phyta,  and  he  suggested,  with  the  critical  sense  for 
which  he  was  distinguished,  the  word  microbe,  to 
which  it  appeared  to  him  that  every  one  could  give 
tlieir  assent. 

'  In  fact,  the  word  microbe,  which  only  signifies  a 
small  living  being,  decides  nothing  as  to  the  animal 
or  vegetable  nature  of  the  beings  in  question.*  It  has 
been  adopted  by  Pasteur,  and  approved  by  Littre, 
whose  competence  to  decide  on  neologisms  is  generally 
admitted ;  it  has  been  in  common  use  in  France  for 
the  last  four  or  five  years,  and  may  now  be  regarded 
as  definitively  adopted  into  the  French  language. 

This  word  has « not  yet  been  fully  introduced  into 

*  Be"champ  terms  microbes  inicrozyma,  or  small  ferments,  since  the 
chemical  reactions  which  result  from  their  vital  activity  are  generally 
fermentations. 


MICROBES  AND  PROTISTA.  O 

the  English  and  German  languages.  In  order  to  in- 
dicate the  organisms  which  produce  diseases,  they 
make  use  of  the  word  Bacteria,  which  is  only  the 
name  of  one  of  the  peculiar  species  assigned  to  this 
group,  and  the  one  with  which  we  have  been  longest 
acquainted.  In  this  case,  the  name  is  generalized  and 
applied  to  an  entire  group. 

The  Italian  authors  who  have  been  recently  occu- 
pied with  the  study  of  microbes  have  on  their  part 
adopted  the  name  Protista,  proposed  by  Hseckel,  and 
of  which  the  sense,  although  not  the  etymology,  is 
almost  the  same  as  that  of  the  word  microbe. 

.  In  reply  to  the  question  whether  there  is  any  real 
advantage  in  establishing  an  intermediate  kingdom 
of  Protista  between  the  two  organic  kingdoms  of 
animals  and  plants,  we  must  answer  in  the  negative. 
This  third  organic  kingdom  only  serves  to  render 
the  structure  of  our  modern  classification  more  com- 
plex ;  and  it  includes,  as  may  be  seen  from  the  list 
given  above,  a  collection  of  very  heterogeneous  groups, 
which  it  would  be  more  simple  to  leave  in  one  or  the 
other  kingdom.  We  should,  in  our  opinion,  approxi- 
mate more  closely  to  Nature's  plan  by  only  admitting 
two  great  kingdoms :  the  organic  kingdom,  which 
includes  plants  and  animals ;  and  the  inorganic  king- 
dom of  minerals.  The  organic  kingdom  should  then 
be  divided  into  two  sub-kingdoms,  animals  and 
plants,  of  which  microbes  or  protista,  or  whatever 
else  they  may  be  called,  should  form  the  connecting 


6  MICROBES,   FERMENTS,  AND  MOULDS. 

link,  and  testify  to  the  common  origin  of  the  two 
great  organic  kingdoms. 

However  this  may  be,  we  shall  make  use  of  the 
word  "microbe"  as  the  general  designation  of  all 
the  minute  organized  beings  which  are  found  on  the 
borderland  between  animals  and  plants.  We  shall 
presently  show  that  in  the  majority  of  cases  these 
beings  may  be  regarded  as  true  plants,  and  this  is  at 
present  generally  admitted  by  most  naturalists. 

Part  played  by  Microbes  in  Nature. — The  part 
played  by  microbes  in  nature  is  an  important  one. 
We  find  them  everywhere  ;  every  species  of  plant  has 
its  special  parasites,  and  this  is  also  the  case  with  our 
cultivated  plants — with  the  vine,  for  example,  which  is 
attacked  by  more  than  a  hundred  different  kinds. 
These  microscopic  fungi  have  their  use  in  the  general 
economy  of  nature  ;  they  are  nourished  at  the  expense 
of  organic  substances  when  in  a  state  of  putrefac- 
tion, and  reduce  their  complex  constituents  into  those 
which  are  simpler — into  the  soluble  mineral  substances 
which  return  to  the  soil  from  which  the  plants  are 
derived,  and  thus  serve  afresh  for  the  nourishment  of 
similar  plants.  In  this  way  they  clear  the  surface  of 
the  earth  from  dead  bodies  and  faecal  matter ;  from  all 
the  dead  and  useless  substances  which  are  the  refuse 
of  life,  and  thus  they  unite  animals  and  plants  in  an 
endless  chain.  All  our  fermented  liquors,  wine,  beer, 
vinegar,  etc.,  are  artificially  produced  by  the  species 
of  microbes  called  ferments;  they  also  cause  bread 


MICROBES  AND  PROTISTA.  7 

to  rise,  and  from  this  point  of  view   they  are  pro- 
fitable in  industry  and  commerce. 

But  in  addition  to  these  useful  microbes,  there  are 
others  which  are  injurious  to  us,  while  they  fulfil 
the  physiological  destiny  marked  out  for  them  by 
nature.  Such  are  the  microbes  which  produce  dis- 
eases in  wine ;  most  of  the  changes  in  alimentary  and 
industrial  substances ;  and,  finally,  a  large  number  of 
the  diseases  to  which  men  and  domestic  animals  are 
subject.  The  germs  of  these  diseases,  which  are  only 
the  spores  or  seeds  of  these  microbes,  float  in  the  air 
we  breathe  and  in  the  water  we  drink,  and  thus 
penetrate  into  the  interior  of  our  bodies. 

Hence  we  see  the  importance  of  becoming  acquainted 
with  these  microbes.  Their  study  concerns  the  agri- 
culturist, the  manufacturer,  the  physician,  the  pro- 
fessor of  hygiene,  and,  indeed,  we  may  say  that  it 
concerns  all,  whatever  our  profession  or  social  position 
may  be,  since  there  is  not  a  single  day,  nor  a  single 
instant,  of  our  lives  in  which  we  cannot  be  said 
to  come  in  contact  with  microbes.  They  are,  in 
fact,  the  invisible  agents  of  life  and  death,  and  this 
will  appear  more  plainly  from  the  special  study  we 
are  about  to  make  of  the  more  important  among 
them. 

Since  it  is  easier  to  know  and  observe  beings  which 
are  visible  to  the  naked  eye,  we  shall  first  speak  of 
fungi — that  is,  of  the  larger  microbes,  with  whose 
habits  and  organization  we  are  also  best  acquainted. 


8  MICEOBES,   FERMENTS,   AND  MOULDS. 

We  will  then  go  on  to  the  study  of  the  more  minute 
ferments ;  and  finally  to  that  of  bacteria  (Schizophyta 
or  Schizomycetes),  which  are,  strictly  speaking,  mi- 
crobes, and  which  only  become  visible  with  the  aid  of 
the  microscope. 


CHAPTER  L 

PARASITIC   FUNGI   AND  MOULDS. 

I.  GENERAL  REMARKS  ON  FUNGI. 

EVERY  one  is  acquainted  with  the  field  and  forced 
mushrooms,  two  varieties  of  one  and  the  same  species, 
wild  or  cultivated,  and  often  seen  at  table.  It  is  less 
generally  known  that  the  truffle  is  also  a  fungus; 
and  that  the  large  class  of  fungi  includes  moulds  and 
many  parasites  which  are  more  or  less  microscopic, 
which  live  at  the  expense  of  wild  and  cultivated 
plants,  and  attack  animals  and  also  the  human  subject. 
Fungi  are  among  the  lower  plants,  and  differ  from 
higher  orders  in  their  mode  of  life.  It  is  well  known 
that  the  large  majority  of  plants  are  not  nourished  only 
by  absorbing  the  mineral  salts  which,  in  a  state  of 
solution,  their  roots  derive  from  the  soil,  but  also,  and 
chiefly,  by  decomposing  the  carbonic  acid  of  the  air, 
assimilating  the  carbon  which,  as  cellulose,  enters 
into  the  composition  of  all  their  tissues,  and  giving 
forth  pure  oxygen  to  the  air. 


10 


MICROBES,  FERMENTS,   AND  MOULDS. 


This  function  is  not,  as  it  was  formerly  erroneously 
supposed,  a  respiration  in  the  inverse  form  from  that 
of  animals.  All  plants  without  exception  breathe 
like  animals  by  absorbing  oxygen.  The  assimilation 
of  carbon  is  a  true  nutrition,  and  as  the  decomposition 
of  the  carbonic  acid  gas  which  results  from  this  assi- 
milation sets  free  a  much  larger  quantity  of  oxygen 
than  the  plant  requires  for  itself,  it  was  for  a  long 
while  believed  that  plants  really  breathed  the  car- 
bonic acid  gas  of  the  air,  in  the  inverse  method  to 
that  of  animals. 


Fig.  I. — Agaricas  in  different  stages  of  development :  2,  3,  a  vertical  section  showing 
the  formation  of  the  head.  The  hyphse  of  the  mycelium  are  shown  in  the  lower 
part  of  the  figure. 

The  assimilation  of  carbon  is  effected  by  the  leaves 
and  green  parts  of  plants ;  the  green,  granular  sub- 
stance termed  chlorophyll,  which  solely  gives  them 
this  colour,  as  may  be  shown  by  the  microscope,  and 
which  alone  subserves  this  function  of  nutrition. 
Fungi,  however,  have  no  leaves  nor  other  green  parts ; 
that  is,  they  have  no  chlorophyl.  They  derive  the 
cellulose  which  they  contain,  as  well  as  all  the  sub- 
stances by  which  they  are  nourished,  either  from 


PARASITIC  FUNGI  AND  MOULDS.  11 

other  plants,  or  from  animals  and  from  the  organic 
substances  which  are  decomposing  in  the  soil,  such 
as  dung  and  dead  bodies.  So  that  it  may  be  said 
of  fungi,  that  they  subsist  like  animals  by  devouring 
plants  or  other  animals ;  not  like  higher  plants,  which 
derive  their  nutriment  from  the  soil  or  the  air,  and 
owe  nothing  to  other  living  beings. 

It  is  for  this  reason  that  some  naturalists  have 
regarded  fungi  as  animals,  and  have  classed  them  in 
the  animal  kingdom.  We  have  seen  that  Haeckel 
and  the  naturalists  of  his  school  have  assigned  them 
to  the  kingdom  of  Protista.  But  setting  aside  their 
mode  of  nutrition,  which  is  likewise  found  in  plants  of 
a  higher  organization,  such  as  the  Orobranchece  and 
some  of  the  Orchidacece,  fungi  really  exhibit  all  the 
characters  of  plants,  and  as  such  we  shall  here  con- 
sider them,  although  they  are  plants  of  a  peculiar 
and  very  low  type. 

The  class  of  fungi  may  be  defined  by  saying  that 
they  are  plants  devoid  of  stems,  leaves,  and  roots ;  that 
they  consist  only  of  cells  in  juxtaposition,  devoid  of 
chlorophyl.  They  never  bear  a  true  flower,  and  are 
simply  reproduced  by  means  of  very  minute  bodies, 
generally  formed  of  a  single  cell,  which  is  called  a 
spore,  and  which  represents  the  seed. 

In  fungi  of  the  highest  type,  such  as  that  commonly 
known  as  the  edible  mushroom,  the  part  which  we 
eat  and  call  the  umbrella  represents  the  flower  or 
floral  peduncle  of  other  plants,  and  is  in  reality  only 


12 


MICROBES,   FERMENTS,  AND  MOULDS. 


the  support  or  covering  of  the  spores,  which  are  fixed 
on  the  radiating  lamellae  that  may  be  seen  on  in- 
verting the  umbrella  (Figs.  2  and  3).  This  umbrella 
or  floral  peduncle  is  the  only  part  of  the  plant  which 
appears  above  the  soil,  or  the  organic  substances  on 
which  the  fungus  grows. 

But  the  really  essential  part  of  the  plant  is  that 


Fig.  2. — Section  of  one  of  the  lamellce 
of  the  umbrella  of  Agaricus  c : 
a,  b,  spores  of  the  hymenium 
(slightly  magnified). 


Fig.  3 — Spores  of  the  hymenium,  greatly 
magnified,  and  resting  on  their  supports 
or  Uasides,  a. 


which  does  not  appear  on  the  surface;  namely,  the 
white  filaments  or  hyphce  which  creep  along  the  soil, 
the  manure,  or  whatever  supplies  the  nutritive  matter, 
and  which  represent  at  once  the  root,  the  stem,  and  the 
branches  of  the  plant ;  this  part  is  termed  the  mycelium. 
We  shall  presently  see  that  many  of  the  lower  fungi 
are  without  the  organ  we  have  called  the  umbrella,  and 
which  botanists  term  the  hymenium  or  organ  of  repro- 
duction, and  consequently  consist  only  of  mycelium. 


PARASITIC  FUNGI  AND  MOULDS. 


13 


In  this  case,  the  spores  or  seeds  are  developed  in  the 
cells  of  the  mycelium  itself. 

This  latter  mode  of  reproduction  also  occurs  in  the 
higher  fungi,  which  therefore  possess  two  modes  of 
reproduction  and  two  kinds  of  spores :  exogenous 
spores,  which  are  externally  developed,  as  we  see  on 
the  hymenium  (Fig.  2);  and  endogenous  or  internal 
spores,  which  are  developed  in 
the  mycelium  (Fig.  4).  These 
spores  not  only  differ  in  the 
site  of  their  origin,  but  also  in 
their  form,  size,  structure,  and 
in  the  end  they  fulfil  in  the 
reproduction  of  the  fungus. 
There  are  in  many  cases  several 
forms  of  exogenous  spores. 

Classification  of  Fungi. — 
The  nature  of  the  spores,  and 
the  very  varied  mode  of  reproduction,  have  led  to 
the  classification  of  fungi  in  a  certain  number  of 
groups,  of  which  we  need  only  cite  the  most  im- 
portant, and  those  which  chiefly  concern  our  present 
point  of  view.  Such  are — 

1.  The  Hymenomycetes. 

2.  The  Basidiomycetes. 

3.  The  Ascomycetes. 

4.  The  Oomycetes. 

Each  of  these  groups  is   subdivided  into  several 
sections  or  families.     Ferments  and  Schizomycetes,  or 


Fig.  4.— Endogenous  spores  from 
the  mycelium  of  Agaricus 
(much  magnified). 


14  MICROBES,  FERMENTS,  AND  MOULDS. 

microbes,  properly  so  called,  are  still  often  assigned  to 
the  class  of  fungi.  We  shall  speak  of  them  separately, 
and  give  our  reasons  for  distinguishing  them  from 
true  fungi. 

Hymenomycetes  are  the  fungi  which  possess  the 
hymenium  or  umbrella;  all  the  edible  species  are 
included  in  this  class,  together  with  a  great  number 
of  extremely  poisonous  species.  They  are  generally 
of  considerable  size,  and  only  a  few  among  them  are 
true  parasites ;  they  do  not,  therefore,  enter  into  the 
plan  of  this  work,  and,  in  spite  of  the  interest  they 
present,  we  shall  content  ourselves  with  the  brief 
notice  of  them  we  have  just  given.  The  other  groups 
must,  however,  detain  us  longer. 


II.  THE  BASIDIOMYCETES  :    UREDINE^:,  THE  BUST  OF 
WHEAT  AND  GRASSES. 

The  name  of  cereal  rust  is  given  to  a  parasitic 
affection  caused  by  a  minute  microscopic  fungus  which 
is  developed  on  the  leaves  of  wild  and  cultivated 
grasses.  This  rust  appears  in  the  form  of  orange 
patches,  which  gradually  spread  over  the  blades  of 
wheat  and  other  grasses,  and  its  common  name  is 
due  to  this  colour.  Many  of  the  plants  belonging 
to  other  families  are  attacked  by  analogous  parasites, 
and  these  fungi  are  all  assigned  by  naturalists  to 
the  genus  Uredo,  and  to  the  family  of  the  Basidio- 
mycetes  or  Uredinece. 


PARASITIC  FUNGI  AND  MOULDS. 


15 


Basidiomycetes  have  no  endogenous  spores,  but 
they  may  have  as  many  as  four  forms  of  exogenous 
spores.  This  is  the  case  with  the  rust  of  wheat, 
termed  by  naturalists  Uredo  or  Pucdnia  graminis, 
which  appears  in  the  spring  on  the  blades  of  this 
plant.  The  patches  of  rust  are  covered  with  a  fine 
dust,  which,  under  the  microscope,  is  seen  to  consist 
of  small  elongated  bodies  of  a  reddish  brown,  resting 
on  a  filament;  these  are  the  first 
spores  of  the  fungus,  and  are 
termed  uredospores  (Fig.  5).  If 
they  are  scattered  over  a  blade 
of  wheat  which  was  previously 
healthy,  they  germinate  by  means 
of  a  hypha  of  mycelium,  which 
penetrates  the  leaf  and  develops 
a  fresh  patch  of  rust.  In  harvest- 
time  the  patches  are  of  a  darker, 
almost  black  shade,  owing  to  the 
development  of  a  second  kind  of  ^^ST^^fS** 
spore.  These  are  pear-shaped,  SS^SftSSi 
divided  in  two,  with  an  enveloping  ^*£*ff£^ 
membrane  of  considerable  thickness ;  they  are  called 
teleutospores  (Fig.  5). 

Teleutospores  cannot  germinate  on  a  healthy  blade 
of  wheat,  and  consequently  do  not  communicate  rust. 
They  may  remain  through  the  winter  on  thatch 
or  wheat  straw,  awaiting  the  ensuing  spring,  and 
even  then  they  cannot  be  developed  upon  a  blade 


16  MICROBES,  FERMENTS,  AND  MOULDS. 

of  wheat,  but  only  upon  the  leaves  of  another  plant, 
the  barberry. 

Borne  by  the  dew  or  by  a  drop  of  rain  on  to  the 
young  leaves  of  the  barberry,  the  teleutospores  germi- 
nate, and  form  reddish-brown  patches  which  affect 
both  sides  of  the  leaf.  On  its  lower  surface  the 
spores  are  smaller,  and  are  termed  spermata;  their 
function  is  not  thoroughly  understood.  The  larger 
spores  on  the  upper  surface  are  called  acidiospores 
(Fig.  6),  and  with  these  we  are  more  concerned,  since 


Fig.  6.— Section  of  a  burberry-leaf  bearing  two  cecidiospores,  more  or  less  developed, 
of  Puccinia  graminis  (much  magnified). 

they  are  destined  to  return  to  the  wheat,  rye,  or  other 
grasses,  in  order  to  reproduce  the  original  rust. 

When  they  are  placed  on  a  blade  of  one  or 
other  of  these  grasses,  the  cecidiospores  germinate  at 
once,  and  it  is  soon  covered  with  patches  resembling 
those  of  the  preceding  year;  when  these  patches  are 
numerous,  they  dry  up  the  blade  and  destroy  the  ear. 

Hay  and  straw  affected  by  rust  should  never  be 
given  to  animals  as  food,  since  such  food  may  produce 
disease. 

Thus  it  appears  that  Puccinia  graminis  presents 
the  phenomenon  of  alternation  of  generations ;  that  is, 


PARASITIC  FUNGI  AND  MOULDS.  17 

the  complete  development  of  the  fungus  is  only  effected 
by  its  transference  from  one  plant  to  another.  This 
phenomenon  may  be  frequently  observed  in  animal 
and  vegetable  parasites,  and  it  seems  to  be  designed 
in  order  to  secure  the  preservation  of  the  parasitic 
species,  by  permitting  it  to  grow  on  two  plants  in 
succession,  of  which  the  development  occurs  at  different 
periods  of  the  year ;  such  is  the  case  with  the  barberry, 
which  is  developed  in  early  spring,  while  wheat  is 
developed  in  summer.  For  a  long  while  it  was 
believed  that  (Eeidium  berberidis,  Uredo  linearfe, 
and  Puccinia  graminis  were  so  many  distinct 
species;  but  it  is  now  known,  as  we  have  stated, 
that  they  are  only  three  successive  phases  of  the 
development  of  a  single  species.* 

Other  Uredinece,  constituting  the  modern  varieties 
of  Ustilago  and  Tilletia,  are  more  apt  to  affect  the 
ears  of  wheat  and  other  grasses.  This  disease  is  termed 
by  agriculturists  smut  or  caries  (Uredo  carlo  or 
Ustilago  segetum,  and  Tilletia  caries).  The  diseased 
grain  merely  appears  to  be  of  a  somewhat  darker 
colour,  but  on  pressing  it  between  the  fingers,  there 
issues  from  it  a  blackish,  oily  pulp,  which  smells 
like  rotten  fish.  Bread  made  from  the  flour  of  such 
corn  has  an  acrid  and  bitter  taste,  and  although  it 
does  not  appear  to  be  directly  injurious  to  health, 

*  So,  again,  (Eeidium  rhamni  (Nerprun  or  Boimlaine)  produce 
Uredo  rubiyo-vera  and  Piicciuia  coronata  of  wheat  and  oats.  (See 
Fig.  7.) 


18 


MICROBES,  FERMENTS,  AND  MOULDS. 


it  cannot  be  regarded  as  fit  for  food.  The  dust 
arising  from  these  fungi  often  produces  in  threshers 
in  a  barn  an  irritating  cough,  which  ceases  when 
they  are  no  longer  subject  to  the  exciting  cause. 

The  verdet,  or,  as  the  Italians  call  it,  verderame  of 
maize  is  due  to  the  presence  of  the  same  parasite 
(Ustilago  segetum,  Uredo  carlo,  or  Sporisorium  mazdis) 
on  the  grains  of  maize,  and  for  a  long  while  it  was 
believed  to  produce  pellagra,  a  common  disease  among 
the  peasants  who  live  on  maize.  It  is  now  known 
that  pellagra  is  due  to  the  growth  of  another  fungus, 
much  resembling  the  ergot  of  rye,  of 
which  we  shall  speak  presently. 

Other  species  of  Uredinece  attack 
sorghum,  rice,  etc.,  and,  indeed,  very 
many  plants  are  affected  by  parasitic 
fungi  belonging  to  the  genus  Puccinia 
and  to  allied  genera,  and  it  is  probable 
that  they  almost  all  present  the  phe- 
nomenonxof  alternation  of  generations. 
A  simple  means  of  freeing  our  fields  from  the  rust 
of  wheat  is  indicated  by  what  we  now  know  of  the 
alternation  of  generations  which  ensures  the  propaga- 
tion of  this  fungus.  We  must  destroy  all  the  barberry 
bushes  which  are  found  in  the  vicinity  of  cornfields. 
Popular  opinion,  although  ignorant  of  the  phenomenon 
of  alternation  of  generations,  has  long  regarded  the 
neighbourhood  of  the  barberry  as  the  principal  cause 
of  the  rust  of  cereals. 


Fig.  7.  —  gpores  of 
Uredo  rubigo  vera, 
or  Puccinia  coro- 
nata. 


PARASITIC  FUNGI  AND  MOULDS.  19 

In  18G9,  De  Taste  ascertained  that  in  the  parish  of 
Chambray,  after  the  peasants  had  uprooted  all  the 
barberries  which  grew  in  the  hedges,  the  harvest, 
which  had  been  bad  in  the  foregoing  year,  was 
gathered  in  under  normal  conditions  for  three  suc- 
cessive years.  After  the  Lyons  Railway  Company  had 
planted  a  barberry  hedge  to  fence  the  railway  in  the 
parish  of  Genlis  (Cote-d'Or),  the  cornfields  bordering 
on  the  line  were  attacked  by  rust  in  an  aggravated 
form.  An  inquiry  made  by  the  company  showed 
that  the  disease  was  due  to  the  barberry,  and  that 
where  that  plant  was  not  found,  the  wheat  was  not 
affected  by  rust.  On  the  other  hand,  a  single  shrub 
of  barberry  caused  the  disease  to  appear  in  a  field 
in  which  it  had  never  occurred  before. 

The  smut  of  wheat  may  be  destroyed  by  the 
application  of  quicklime,  either  dry  or  dissolved  in 
water,  which  destroys  the  fungus  or  checks  its  develop- 
ment. Seed  corn  should  always  be  subjected  to  this 
operation  when  affected  by  smut.  In  default  of  quick- 
lime, sulphate  of  copper  is  sometimes  used,  which 
may  be  injurious,  or  sulphate  of  soda,  dissolved  in 
water  (eight  kilograms  to  the  hectolitre).  This  should 
be  done  the  day  before  the  seed  is  sown.  In  the  case 
of  corn  intended  for  food,  another  process  called  pelle- 
tage  must  be  employed;  this  consists  in  the  frequent 
stirring  of  the  granaried  corn,  either  with  the  hand 
or  with  Vallery's  movable  granary  floor,  so  as  to  dry 
and  aerate  it,  and  expel  the  dust  and  damp,  which  are 
favourable  to  the  development  of  fungi. 


20  MICROBES,  FEEMENTS,  AND  MOULDS. 


III.    ASCOMYCETES;  ERGOT  OF    RYE;    THE  MOULD  OF 

LEATHER  AND  DRIED  FRUITS. 

In  distinction  from  the  species  just  described,  the 
fungi  in  this  group  possess  endogenous  spores,  enclosed 
in  a  sac  or  special  envelope  which  is  called  an  ascus ; 
hence  the  name  of  the  family.  Truffles,  or  Tuberacece, 
are  only  reproduced  by  the .  spores  contained  in  these 
asci;  but  most  of  the  other  ascomycetes  present  in 
addition  several  forms  of  spores,  and  the  phenomenon 
of  alternation  of  generations  has  led  to  the  belief  that 
in  this  case,  as  in  that  of  the  foregoing  group,  many  of 
the  so-called  species  are  only  successive  transformations 
of  one  and  the  same  species.  This  is  the  case  with 
the  ergot  of  rye,  a  product  used  in  medicine;  it  is, 
however,  a  serious  and  dangerous  disease  of  several 
of  our  cereals,  and  particularly  of  rye  (Fig.  8). 

Ergot  is  caused  by  a  minute  parasitic  fungus  which 
attacks  the  ear  of  rye  when  it  is  in  flower.  The 
young  flower  is  covered  with  a  white  mass,  consisting 
of  microscopic  spores,  formerly  termed  sphacelium 
(Fig.  9).  These  spores  reproduce  themselves  on  other 
flowers,  and  propagate  the  evil. 

The  mycelium  formed  by  the  germination  of  the 
sphacelium  affects  the  grain,  forms  in  it  a  thick  felt- 
work,  and  is  developed  so  as  to  constitute  the  elongated 
substance  termed  sclerotis  (on  account  of  its  hardness), 
or  ergot ;  it  is  called  at  this  stage  Claviceps  purpurea. 


PARASITIC  FUNGI  AND  MOULDS.  21 

The  sphacelium  surrounding  it  falls  off,  and  until  the 


Fig.  9.— Sphacelium  or 
t'luriceps  purpurea, 
tliotir-t  siatf-  ol'ergot 
(magnified). 


Fig.  P.— Ear  of  rye,  on 
which  tlicro-  are  several 
grains  of  ergot. 


Fig  10.— Ergot  bearing  the  organs 
of  fructification  (magnified). 


following  spring  the  ergot  remains  stationary  on  the 
soil  on  which  it  has  fallen. 


22 


MICROBES,  FERMENTS,  AND  MOULDS. 


In  the  spring,  owing  to  the  heat  and  moisture,  the 
hyphse  of  the  sclerotis  swell  and  send  forth  numerous 
branches,  bearing  at   their  ex- 
tremity a  sort  of  rounded  head, 
in  which  the  asci  or  peritheces 
are  developed  (Figs.  10,  11,  12) ; 
the   endogenous  spores   issuing 
from  these  asci  germinate   on 
the    rye-blossom,    and   produce 
there  a  fresh  sphacelium,  then 
a   second    ergot,    thus    always 
passing  through  the  same  cycle 
of  alternation  of  generations. 
Most  of  the  Graminacece  and  several  Cyperacece  are 
capable  of  producing  ergots  resembling  those  of  rye, 


Fig.  11.— One  of  the  heads  or 
organs  of  fructification  in 
ergot,  still  more  magnified, 
a,  peritheces. 


Fig.  12.— Portion  of  preceding  figure  tinder  a  very  high  magnifying  power,  showing 
at  &  the  asci,  and  at  c  the  spores  issuing  from  the  asci  or  peritheces. 

and  possessing  the  same  medical  properties.    The  sug- 
gestion has  been  made  that  instead  of  the  ergot  of  rye 


PARASITIC   FUNGI  AND  MOULDS.  23 

the  ergot  of  wheat  should  be  used  in  medicine ;  it  is 
larger,  harder,  and  more  elongated  in  form,  and  it  also 
appears  to  be  less  perishable. 

Ergot  of  rye,  especially  when  powdered,  strongly 
resembles  meat  in  smell,  and  only  becomes  unpleasant 
when  the  powder  is  spoiled  by  being  kept  in  a  damp 
place ;  it  then  smells  like  rotten  fish,  and  this  is  the 
case  with  many  other  fungi. 

At  first  the  taste  is  not  very  apparent,  but  it  after- 
wards produces  on  the  pharynx  a  somewhat  persistent 
sense  of  constriction.  The  chief  action  of  this  drug 
consists  in  producing  contraction  of  unstriated  muscu- 
lar fibres,  especially  those  of  the  uterus.  Ergotine 
and  ergotinine  are  extracted  from  it,  and  these,  which 
are  its  active  principles,  are  often  employed  in  thera- 
peutics in  preference  to  raw  ergot. 

In  large  doses  ergot  is  a  strong  poison.  It  then 
produces  characteristic  symptoms,  dilatation  of  the 
pupils,  retardation  of  the  circulation,  vertigo,  stupor, 
and  even  death. 

Bread  made  with  flour  from  which  the  ergot  has 
not  been  extracted  may  produce  the  grave  symptoms 
known  as  ergotism,  and  these  soon  become  fatal  unless 
the  use  of  such  bread  is  discontinued.  Sometimes 
nervous  symptoms  predominate,  and  this  is  termed 
convulsive  ergotism ;  sometimes  the  disease  takes  the 
form  of  gangrene  of  the  extremities,  or  gangrenous 
ergotism,  but  these  two  forms  are  only  two  phases  of 
one  and  the  same  disease,  and  often  occur  in  the  same 


24  MICKOBES,  FEKMENTS,  AND  MOULDS. 

individual.  In  countries  where  rye  bread  constitutes 
the  chief  food  of  the  rural  populations,  as  in  Brabant, 
the  north  of  France,  Orleannais  and  Le  Blaisois,  fatal 
epidemics  have  been  recorded  at  different  times  in  the 
Middle  Ages,  under  the  name  of  St.  Anthony's  fire. 
The  first  symptoms  are  a  species  of  intoxication,  sought 
after  by  the  peasants,  and  becoming  habitual,  like 
alcoholic  drunkenness,  up  to  the  moment  when  con- 
vulsions and  gangrene  set  in,  and  death  soon  follows. 

Ergot  of  maize  produces  analogous  phenomena.  In 
countries  where  maize  bread  and  cakes  are  in  use, 
as  in  Italy  and  South  America,  it  appears  to  be  the 
cause  of  the  disease  improperly  called  Pelade.  Of  this 
the  shedding  of  the  hair  and  skin  is  the  first  symptom.* 
Fowls  which  feed  on  ergotized  maize  lay  eggs  which  are 
devoid  of  shell,  owing  to  their  premature  expulsion 
from  the  uterus ;  their  combs  become  black,  shrivel, 
and  finally  drop  off;  and  they  even  shed  their  beaks. 
All  these  phenomena  may  be  easily  explained  by  the 
action  of  ergot  on  the  muscular  fibres  of  the  uterus, 
and  of  the  blood-vessels. 

Recent  research  has  shown  that  Pelade  is  identical 
in  its  cause  and  external  symptoms  with  the  disease 
known  in  northern  Italy  and  in  the  south  of  France  as 
pellagra,  and  in  Spain  as  the  rose  sickness.  The  latter 

*  We  shall  presently  see  that  the  name  Pelade  was  formerly  given 
to  another  parasitic  affection,  peculiar  to  that  part  of  the  skin  covered 
with  hair.  These  two  diseases  must  not  be  confounded,  notwithstand- 
ing the  similarity  of  name,  since  they  are  produced  by  two  fungi 
belonging  to  different  groups. 


PARASITIC  FUNGI  AND  MOULDS.  25 

name  is  clue  to  the  red  stains  which  cover  the  skin, 
afterwards  drying  up  and  falling  off  in  the  form  of 
scales.  At  first  the  general  health  is  not  affected,  and 
several  years  may  intervene  before  the  occurrence  of 
vertigo,  a  want  of  appetite,  emaciation,  and  finally  the 
torpor  and  convulsions  which  precede  death.  These  ill 
effects  may  be  prevented  by  baking  the  maize  before 
grinding  it,  according  to  the  process  in  use  in  Burgundy. 

There  is  another  very  common  fungus  also  belong- 
ing to  the  group  of  ascomycetes,  termed  Eurotium 
repens.  This  mould  appears  upon  leather  which  has 
been  left  in  a  damp  place,  and  on  vegetable  or  animal 
substances  in  process  of  decomposition  or  badly  pre- 
served, and  especially  upon  cooked  fruits. 

This  mould  is  of  a  sombre  green,  a  colour  by  no 
means  due  to  the  presence  of  chlorophyl.  On  the 
mycelium,  which  spreads  over  the  substance  of  the 
leather  or  of  the  fruit-skin,  small  stems  are  developed, 
consisting  of  a  jointed  tube,  and  terminating  in  an 
enlarged  head  on  which  chaplets  of  small  grains  are 
formed,  each  of  which  is  a  spore.  This  was  formerly 
termed  Aspergillua  glaucus,  and  was  regarded  as  a 
peculiar  species  (Fig.  13). 

When,  however,  this  mould  is  developed  in  a  place 
in  which  the  supply  of  air  is  limited,  small  gold-coloured 
balls  may  often  be  observed  beside  or  in  the  midst  of  the 
stems,  and  these  are  filled  with  asci,  each  containing 
eight  spores.  This  second  form  has  been  termed  Euro- 
tium  repens.  It  has  recently  been  ascertained  that 


26 


MICROBES,  FERMENTS,  AND  MOULDS. 


the  balls  in  question  are  produced  from  the  same 
mycelium  as  Aspergillus  glaucus,  and  that  conse- 
quently the  chaplet  of  stalks  and  the  balls  filled  with 
asci  are  merely  two  organs  of  the  same  fungus. 


Fig.  13.— Aspergillus  glaucus,  mould  on  leather  and  rotten  fruits  :  a,  hypha  bearing 
the  chaplet  of  spores  b ;  c,  a  germinating  spore ;  d,  ball  of  Eurotium ;  e,  ascus 
enclosing  the  endogenous  spores  (magnified). 

The  chaplet  of  spores  in  Aspergillus  glaucus  repre- 
sent the  white  exogenous  spores,  or  the  sphacelium  of 
the  ergot  of  rye,  and  those  which  are  subsequently 


PARASITIC  FUNGI  AND  MOULDS. 


27 


produced  in  the  yellow  balls  correspond  with  those 
which  issue  from  the  asci  developed  on  the  sclerotis ; 
these  are  endogenous  spores. 

Many  of  the  parasitic  fungi  belonging  to  the  genera 
Erysiplie,  Sphceria,  Sordaria,  Penicillium,  etc.,  pre- 
sent a  similar  mode  of  vegetation,  and  affect  a  large 
number  of  plants.  Such  is  the  Oidium  of  the  vine 
(Erysiphe  Tuckeri}  to  which  we  shall  presently  revert. 


IV.  OOMYCETES,  MUCORINE.E,  OR  MOULDS,  PROPERLY 
so  CALLED;  PERONOSPOREJS ;  THE  POTATO-FUNGUS. 

In  all  the  parasitic  fungi  of  which  we  have  hitherto 
spoken  there  is  no  sexual  reproduction  analogous  to 
that  of  the  higher  plants ;  there  are  no  male  and  female 
organs  comparable  to  the  stamens  and  pistil.  This 
sexual  reproduction  exists  in  the  oomycetes,  although 
only  in  a  very  elementary  form.  In 
addition  to  the  ordinary  spores  which 
we  have  noticed  in  other  fungi,  there 
are  others  termed  oospores,  which  are 
formed  by  the  fusion  of  the  originally 
distinct  contents  of  two  different 
cells.  In  the  family  of  the  mucorinese, 
which  includes  most  of  the  fungi 
commonly  called  moulds  (Fig.  14-), 
the  two  cells  of  which  the  contents 
are  fused  together  are  similar.  In  the  peronosporeae, 
however,  which  includes  the  potato-fungus,  one  of  the 


.Fig.  14. — Mucor  <ani- 
nut,  the  mould  on 
dog's  excremeut  (mag- 
nified). 


28 


MICROBES,  FERMENTS,  AND  MOULDS. 


cells  is  larger  than  the  other,  and  persists  alone  up  ta 
the  moment  when  the  oospore  is  mature.  It  must, 
therefore,  be  regarded,  as  the  female  cell ;  while  the 


Fig.  15.— Reproductive  organs  of  Mucor  mucedo  (much  magnified). 

other,  which  is  smaller  and  soon  withers  away,  is  the 
male  cell. 

The  mycelium  of  the  oomycetes  is  developed  in  a 
mpre  or  less  liquid  medium,  like  all  other  decomposing 
and  putrefying  substances.  The  ordinary  spores  are 


PARASITIC  FUNGI  AND  MOULDS. 


29 


very  small,  and  are  formed  within  a  small  enlargement 
(sporangium)  borne  on  a  free  hypha  of  the  mycelium. 
Their  succession  is  constant  and  numerous  as  long  as 
the  plant  is  in  a  favourable  medium  in  which  it  can 
flourish.  The  spores  which  are  found  in  the  same 
medium  germinate,  and  reproduce  a  mycelium  similar 
to  that  from  which  they  had  their  origin. 


Fig.  16. — Reproductive  organs  of  Peronospora  cdlotheca  (much  magnified). 

The  oospores  may  be  as  much  as  a  thousand  times 
larger  in  volume  than  ordinary  spores.  They  are  only 
formed  when  the  growth  of  the  fungus  is  on  the  wane, 
as,  for  instance,  when  the  substance  serving  as  a  sup- 
port to  the  mycelium  is  drying  off:  a  long  period  may 
elapse  before  they  germinate  (Figs.  15  and  16). 


30  MICROBES,   FEEMENTS,   AND  MOULDS. 

Fig.  15  represents  the  reproductive  organs  of 
Mucor  mucedo.  1  is  the  sporangium  filled  with 
ordinary  spores ;  in  2,  the  wall  of  the  sporangium 
has  disappeared,  so  as  to  show  the  free  spores  round 
the  central  columella ;  3  and  4  represent  the  germina- 
tion of  these  spores,  giving  forth  their  hyphse ;  5  gives 
the  conjugation  of  the  sexual  spores,  which  are  fused 
into  one  large  oospore,  6 ;  of  this  we  see  the  germina- 
tion in  7,  and  it  produces  a  hypha  terminating  in  a 
sporangium. 

Fig.  16  represents  the  same  organs  in  a  Perono- 
spora.  In  1  we  see  the  mycelium  of  the  fungus 
penetrating  the  tissue  of  the  infected  plant;  in  2, 
the  fructifying  apparatus  containing  the  ordinary 
spores  issues  through  a  stoma,  ramifies,  and  produces 
sporangia  at  the  extremity  of  each  branch ;  in  3  and 
4  we  see  two  spores  which  have  issued  from  these 
sporangia  germinating  and  penetrating  the  epidermis 
of  a  leaf  through  the  stomata  (a,  6) ;  in  5  we  see 
the  conjugation  which  has  taken  place  between  two 
dissimilar  cells :  the  male  cell,  smaller  in  size 
(antheridium)  is  applied  to  the  large  female  cells 
(pogonium),  and  after  this  mode  of  fertilization  it 
is  termed  an  oospore,  which  is  represented  in  6. 

Mucor  mucedo,  and  other  species  of  the  same 
genus,  form  the  small  downy  tufts  of  a  greyish  white 
colour  which  may  be  observed  on  mouldy  bread,  rotten 
fruits,  and  on  the  excrement  of  horses,  dogs,  and 
rabbits.  When  examined  under  the  microscope,  the 


PARASITIC  FUNGI  AND  MOULDS.  31 

filaments  of  which  these  tufts  consist  display  at  their 
extremities  the  sporangia  represented  in  Fig.  15,  1. 
On  rotten  fruits,  the  spores  of  these  fungi  germinate 
in  five  or  six  hours  by  introducing  their  hyphse 
through  the  epidermis.  Sleepiness,  which  is  only  the 
first  stage  of  rottenness,  is,  according  to  Davaine, 
to  be  ascribed  to  the  action  of  these  fungi.  Fruit  in 
this  mouldy  condition  is  sometimes  unwholesome. 

The  potato-fungus,  Peronospora  infestans,  is  one 
of  the  most  dreaded  scourges  of  this  valuable  plant. 
It  attacks  the  lower  surface  of  the  leaves  and  stalks, 
and  appears  in  the  month  of  July,  in  the  form  of 
brown  patches.  The  long  hyphse  penetrate  deeply 
beneath  the  epidermis,  and  will  even  propagate  them- 
selves on  the  tubers. 

Among  the  causes  which  produce  or  promote  this 
disease,  agriculturists  place  the  excessive  moisture 
of  the  soil,  setting  the  plants  too  late  in  the  season, 
the  use  of  bad  seed,  the  premature  and  exhausting 
germination  of  the  tubers  before  they  are  planted, 
and  the  use  of  fresh  dung  which  is  not  sufficiently 
decomposed. 

The  following  process  is  indicated  as  likely  to 
prevent  the  development  of  this  parasite.  In  the 
spring,  the  first  protective  ridge  should  be  prepared 
with  a  flat  top,  from  eight  to  ten  centimetres  high, 
and  from  twenty-five  to  thirty  centimetres  wide. 
In  the  first  fortnight  of  August,  a  second  protective 
ridge  should  be  earthed  up,  of  which  the  edge  should 


32  MICROBES,  FERMENTS,  AND  MOULDS. 

be  acutely  sloped,  and  the  stalks  of  the  plant  should 
be  turned  down  into  the  furrow,  so  that  any  spores 
which  may  be  on  the  leaves  may  be  washed  off  them 
by  the  rain,  and  not  come  into  contact  with  the  stem 
and  roots  of  the  plant. 

It  is  probable  that  earth-worms  diffuse  the  spores 
of  this  fungus,  as  well  of  those  of  many  other 
microbes. 

According  to  Prillieux,  beetroot  is  attacked  by 
another  species  of  Peronospora,  which  causes  the 
leaves  of  the  plant  to  wither  and  fall.  The  remedy 
consists  in  burning  the  dead  leaves  on  which  the 
oospores  remain  during  the  winter,  or,  at  any  rate, 
in  not  allowing  them  to  be  placed  on  the  dung-heap. 

The  mildew  which  affects  the  vine  is  also  a  species 
of  Peronospora  (P.  viticold)  as  we  are  about  to  show. 


V.  PARASITIC    FUNGI    OF    THE   VINE:   OIDIUM, 
MILDEW,  ETC. 

The  parasites  of  the  vine  are  so  numerous  as  to 
require  a  separate  chapter.  Some  years  ago,  in  1870, 
fiftv  of  them  were  enumerated  b}^  Roumeguere,  a  well- 
known  specialist,  and  the  number  is  now  more  than 
doubled.  We  shall  only  now  speak  of  the  more 
important,  of  those  which  are  especially  injurious 
to  the  vine,  and  which  consequently  are  the  most 
interesting  to  us. 


PARASITIC  FUNGI  AND  MOULDS.  33 

O'idium.  —  0'idium,  or  Erysiphe  Tuckeri  —  so 
called  from  the  name  of  the  vine-grower  by  whom 
it  was  first  described — has  been  longest  known  to 
us  among  these  parasitic  fungi.  It  belongs  to  the 
group  of  Ascomycetes,  and  appears  to  have  reached 
us  from  America  in  1845,  in  which  year  it  was  first 
observed  in  England.  Thence  it  passed  over  to 
France.  In  1847  it  was  noticed  in  the  neighbourhood 
of  Paris ;  and  afterwards,  in  1850-1851,  in  the  south 
of  France,  where  for  twenty-five  or  thirty  years  it 
raged  with  such  intensity  as  to  threaten  for  some 
years  the  almost  complete  destruction  of  the  vine- 
yards, a  destruction  which  is  now  taking  place  under 
the  attacks  of  another  parasite,  belonging  in  this 
instance  to  the  animal  kingdom:  Phylloxera  vastatrix. 

The  oidium,  the  white  disease  or  meunier,  was 
equally  destructive  in  the  vineyards  of  Madeira,  so 
that  it  was  necessary  to  uproot  all  the  vines,  and 
replace  them  by  sound  plants  which  were  incapable 
of  bearing  grapes  for  some  years. 

The  oidium  appears  on  the  grape  in  the  form 
of  greyish  filaments,  terminating  in  an  enlarged  head, 
which  contains  an  agglomeration  of  spores,  not  free 
or  in  a  chaplet,  as  in  Aspergillus  (Fig.  13).  These 
spores  escape  as  fine  dust,  diffuse  themselves  in  the 
air,  and  spread  the  disease  afar  with  extreme  facility. 

If  a  spore  lodges  on  a  vine-leaf  under  favourable 
conditions  of  moisture  and  warmth,  it  soon  germinates, 
penetrates  the  epidermis  by  means  of  its  hyphze,  and 


34  MICROBES,   FERMENTS,  AND  MOULDS. 

forms  floury  patches  which  send  forth  a  peculiar 
musty  smell. 

The  oidium  may  remain  latent  on  the  vine-stock 
throughout  the  winter.  In  the  spring  it  reappears 
in  yellowish  patches  on  the  earliest  leaves,  on  which 
it  is  rapidly  propagated  ;  the  plant  languishes,  and 
the  leaves  become  pale  and,  as  it  were,  anaemic. 

Very  dry  weather  is  unfavourable  to  oidium,  and 
so  also  are  heavy  rains,  which  wash  the  fruit  and 
leaves,  and  carry  away  the  spores  on  to  the  soil. 

The  remedy  consists  in  the  application  of  sulphur 
to  the  infected  vines.  Flowers  of  sulphur  is  used, 
which  acts  upon  the  fungus  by  gradually  setting  free 
sulphurous  acid.  Under  this  influence  the  microscope 
shows  that  the  superficial  mycelium  and  the  fragile 
spores  dry  up  as  if  they  were  burnt  (Ed.  Andre'). 
Three  successive  applications  are  necessary,  and  these 
are  made  with  the  help  of  a  special  instrument  in 
the  form  of  a  pair  of  bellows,  to  which  a  rose  is 
affixed,  in  order  to  disseminate  the  flowers  of  sulphur. 
The  first  application  is  made  in  spring,  when  the 
shoots  are  from  eight  to  ten  centimetres  long;  the 
second  directly  after  the  vine  has  blossomed ;  and 
the  third  when  the  grapes  begin  to  ripen.  The  opera- 
tion in  spring  is  the  most  important,  and  should  be 
performed  with  the  utmost  care,  so  as  to  affect  all 
the  hybernating  spores  from  which  the  succeeding 
generations  would  issue.  Not  only  the  upper  and 
lower  sides  of  the  leaves  must  be  dusted,  but  also 


PARASITIC  FUNGI  AND  MOULDS.  35 

the  branches  and  the  stock  itself.  The  third  applica- 
tion should  be  made  early  enough  for  the  sulphur  to 
have  disappeared  from  the  grapes  before  the  vintage 
takes  place.  It  is  evident  that  its  introduction  into 
the  wine  would  have  the  worst  effect :  in  process  of 
fermentation  sulphuretted  hydrogen  would  be  given 
off,  which  is  injurious  to  the  alcohol,  and  this  gas 
would  give  an  unpleasant  taste  to  the  wine. 

The  morning  is  the  best  time  for  applying  the 
sulphur,  since  the  dew  enables  the  powder  to  stick 
to  the  leaves  and  branches;  and  it  should  be  made 
on  a  fine  day,  since  heavy  rain  would  carry  off  the 
sulphur  before  it  has  time  to  act  upon  the  oidium. 

The  sulphur  which  ultimately  reaches  the  soil 
below  the  vine  is  transformed  into  sulphate  of  lime, 
which  is  an  excellent  dressing  for  the  vine. 

Mildew. — This  new  parasite,  of  which  the  scientific 
name  is  Peronospora  viticola,  belongs  to  the  group 
of  Oomycetes.  It  also  comes  to  us  from  America. 
It  was  imported  into  Europe  in  1878,  with  the 
American  plants  destined  to  replace  those  destroyed 
by  the  phylloxera,  and  was  rapidly  diffused  through 
France,  and  thence  to  Algeria.  It  appears  in  the 
form  of  irregular  patches  of  a  whitish  colour,  not 
very  thick,  and  with  an  almost  crystalline  appear- 
ance like  that  of  a  saline  efflorescence  (Planchon). 
It  has  not  the  mouldy  smell  of  oidium,  and  appears 
later  in  the  season,  generally  on  the  autumn  shoots. 
Its  mycelium  penetrates  more  deeply  than  that  of 


36 


MICROBES,  FERMENTS,  AND  MOULDS. 


oidium.  Brown  patches  appear  on  the  upper  surface 
of  the  leaf,  as  if  it  had  been  scorched ;  and  in  corre- 
spondence with  these  there  is  a  delicate  down  "  like 
the  whiteness  of  a  slight  hoar-frost "  (Vaissier)  on  its 
lower  surface.  The  hyphye  issuing  from  the  mycelium 
ramify  at  right  angles,  and  these  branches  bear  the 
spores,  as  in  the  potato-fungus,  Peronospora  infestans 
(Figs.  17, 18).  These  numerous  spores,  diffused  through 
the  air,  are  powerful  sources  of  contagion. 


Fig.  1 1. — Mildew  •.  a,  vertical  section  of  a  leaf,  bearing  tufts  of  Peronospora  viticola 
on  its  lower  surface;  b,  a  withered  leaf,  bearing  the  winter  spores  (oospwes) 
(X  20  diain.). 

This  parasite  destroys  the  tissue  of  the  leaf, 
exhausts  it,  and  finally  causes  it  to  wither  and  fall. 
Those  which  are  least  affected  have  only  diseased 
patches.  The  bunch  of  grapes  and  the  young 
herbaceous  shoots  are  rarely  affected. 

In  addition  to  the  ordinary  or  summer  spores  of 
which  we  have  spoken,  the  sexual  spores  must  be 
noted ;  the  oospores,  or  dormant  winter  spores,  which 


PARASITIC  FUNGI  AND  MOULDS. 


37 


hybernate  in  the  tissue  of  the  leaf  itself  (Fig.  17,  ?>), 

and  germinate  in  the  spring.     The  conjugation  of  the 

sexual  spores,  as  well  as  the  ripening  of  the  summer 

spores,    and   the    germination 

of  the  zoospores   which   issue 

from  them,  can  only  occur  in 

a    drop   of  water,   rain,    dew, 

or  mist,   so  that  a  persistent 

drought  checks  the  propagation 

of  this  fungus. 

The  parasite  injures  the 
stock  by  stripping  it  of  its 
leaves,  thus  hindering  the  nu- 
trition of  the  plant ;  moreover, 
the  grapes,  since  they  are  im- 
perfectly protected  from  the 
sun,  dry  up  before  they  are 
ripe.  Sometimes,  also,  the 
fungus*  attacks  the  grape  itself, 
or  its  peduncle. 

Vines  planted  in  a  moist  soil  resist  its  attacks 
better  than  others,  simply  because  the  nature  of  the 
soil  makes  the  plant  more  vigorous,  and  suitable 
manure  acts  in  the  same  way.  When  the  fungus  is 
developed,  it  may  be  destroyed  by  sulphur  mixed 
with  powdered  lime.  Since  its  mycelium  is  more 
deeply  seated  than  that  of  o'idium,  it  is  necessary 
to  have  recourse  to  more  vigorous  measures  in  order 
to  reach  it.  Powdered  borax  has  also  been  pre- 

! 


Fig.  18.— Group  of  tufts  of  Pero- 
nospt/ra  iuj'tttant,  issuing  irom 
a  stoiua  on  the  lower  surface  uf 
the  leaf  and  bearing  tin-  summer 
spores  (x  120  diaui.). 


38  MICROBES,   FERMENTS,   AND  MOULDS. 

scribed,  in  the  proportion  of  five  grammes  to  a  litre 
of  water ;  also  a  solution  of  sulphate  of  iron,  one 
kilogram  to  two  litres  of  water,  with  which  the 
stock  should  be  washed  fifteen  days  before  the  shoots 
begin  to  start  (Millardet).  Mme.  Ponsot,  in  Bordelais, 
has  used  the  same  substance  mixed  with  lime  (four 
parts  of  powdered  sulphate  of  iron  to  twenty  parts 
of  lime).  The  fallen  leaves  which  contain  the 
winter  spores,  or  oospores,  should  be  burnt  or  buried. 
The  stocks  should  be  irrigated  as  often  as  possible, 
and  the  leaves  should  be  dusted  with  lime  in  order 
to  dry  off  the  dew  or  mist,  which  favours  the  fertili- 
zation of  the  oospores. 

Some  species  of  vines  resist  the  disease  better 
than  others,  and  this  is  the  case  with  the  Labernet, 
a  vine  from  MeMoc,  which  has  remained  almost 
entirely  free  from  it  in  infected  regions  of  Algeria. 

Anthracnosis,  or  Black-rot. — This  fungus,  of  which 
the  name  is  Phoma  uvicola,  or  Sphaceloma  ampelium, 
belongs  to  the  ascomycetes.  Of  all  the  parasites  of 
the  vine  it  was  the  earliest  known,  but  it  was  only 
in  1878  that  its  devastations  were  important  enough 
to  attract  attention.  Like  the  two  preceding  fungi, 
it  is  reproduced  by  spores  carried  afar  by  the  slightest 
breeze.  Heat  and  moisture  are  favourable  to  its  pro- 
pagation, which  is  checked  by  drought. 

It  appears  on  the  young  shoots  in  the  month 
of  May,  in  the  form  of  round  black  spots  which 
gradually  spread  over  the  twigs,  leaves,  and  grapes 


PARASITIC  FUNGI  AND   MOULDS.  39 

The  young  stalks  assume  a  sickly  appearance,  and 
often  wither  off,  together  with  the  leaves  and  fruit. 

When  the  fungus  fastens  on  the  fibro-vascular 
bundles  of  the  leaves  before  their  complete  develop- 
ment, the  leaves  shrivel  and  curl  up,  and  perform  their 
functions  imperfectly ;  when  it  attacks  the  petiole  or 
]>••.! uncle  of  the  bunch  of  grapes,  it  dries  up,  and  the 
destruction  of  all  the  parts  in  dependence  on  it  soon 
follow.  It  is  this  fungus  which,  under  the  name  of 
rot,  now  devastates  the  American  vineyards. 

Sulphur  is  by  no  means  so  efficacious  in  this  case 
as  it  is  with  oi'dium,  but  the  following  treatment  is 
prescribed  by  Fortes : — 

1.  The  primings  of  the  vine  and  other  remains 
of  the  preceding  years  should  be  destroyed,  2.  The 
suckers  and  young  shoots  should  be  dusted,  in  the 
second  fortnight  of  April,  with  slaked  lime  whicli  lias 
been  finely  powdered,  and  this  operation  should  be 
repeated  once  a  fortnight  up  to  the  end  of  June. 
3.  Sulphur  should  be  applied  at  the  usual  times, 
especially  if  there  is  any  oi'dium.  4.  The  vines 
should  be  drained  and  irrigated  as  often  as  possible. 
5.  In  all  cases  in  which  the  fungus  can  be  detected, 
powdered  lime  should  be  applied  at  the  interval  of 
some  days,  alternately  with  the  same  substance  mixed 
with  flowers  of  sulphur. 

Aubernaye,  called  by  the  Italians  the  Slack  di*< 
must  not  be  confounded  with  Anthracnosis.     Accord- 
ing to  recent  researches,  aabcrnage  is  not  produced 


40  MICROBES,  FERMENTS,   AND  MOULDS. 

by  a  fungus,  but  by  a  degeneration  which  is  either 
spontaneous  or,  as  Pirotta  and  Cugini  suggest,  the 
work  of  bacteria,  and  which  consists  in  the  trans- 
formation of  the  cellulose  and  starch  of  the  plant 
into  dextrine,  as  Comes  asserts,  or,  according  to  Pirotta, 
into  tannin. 

This  disease  appears  in  three  stages :  (1)  a  simple 
discolouration  of  the  sap,  which  assumes  a  tawny 
black  shade  without  checking  vegetation ;  (2)  a  begin- 
ning of  necrosis,  which  renders  the  plant  unhealthy ; 
(3)  a  complete  necrosis,  which  affects  the  woody  parts 
and  arrests  the  growth  of  the  plant. 

This  disease  is  contagious,  which  leads  us  to 
believe  that  if  it  is  not  produced  by  a  fungus,  it  is 
at  any  rate  due  to  the  development  of  a  bacterium — 
that  is,  of  a  microbe. 

The  remedy  indicated  by  Italian  naturalists  con- 
sists in  the  application  of  salts  of  potassium,  which 
may  be  extracted  at  small  cost  from  the  ashes  of  the 
vine  branches  which  are  burnt  upon  the  spot. 

JRoesleria  Tiypogea,  or  Rot. — This  parasitic  fungus  is 
found  on  the  vine-roots,  and  has  been  recently  studied 
by  Prillieux.  The  vine  affected  by  this  parasite 
languishes  for  some  years  and  then  dies.  The  evil 
spreads  by  means  of  the  roots  to  adjoining  stocks, 
and  the  parts  affected  spread  like  the  patches  formed 
by  the  phylloxera.  The  roots  rot  away.  This  disease 
has  been  widely  spread  in  Haute  Marne. 

This  small  fungus  is  distinct  from  one  which  bears 


PARASITIC  FUNGI  AND  MOULDS.  41 

the  same  French  name,  PowrvidM,  which  is  found 
in  the  south  of  France,  and  has  been  studied  by 
Planchon  and  Millardet.  These  naturalists  describe 
it  as  formed  by  the  rhizomorphous  mycelium  of 
a  large  hymenomycetous  fungus,  Agaricus  melleus. 
Rcesleria  is  very  different.  It  is  a  small  white  fun- 
gus, with  a  white  or  ash-coloured  head,  from  eight 
to  ten  millimetres  in  size,  of  which  the  mycelium 
lives  in  the  interior  of  the  vine-roots,  penetrating 
and  profoundly  affecting  all  the  tissues  of  the  roots, 
and  producing  in  the  autumn  the  fructification  which 
comes  to  the  surface. 

It  is  generally  developed  in  marly  and  argillaceous 
soils,  after  a  rainy  season,  and  in  the  low-lying  parts 
of  vineyards  on  the  slope  of  a  hill.  It  thrives  in 
the  moisture  which  lies  below  the  surface  of  the  soil, 
and  it  is  therefore  important  to  improve  the  con- 
dition of  those  sub-soils  which  are  impermeable. 

It  is  also  necessary  to  separate  the  stocks,  so  as 
to  prevent  their  roots  from  interlacing,  and  to  uproot 
and  burn  diseased  vines,  since  the  fungus  may  subsist 
for  several  years  in  dead  and  dried  roots.  If,  which 
is  almost  always  the  case,  any  fragments  of  roots 
remain  in  the  ground,  they  will  reinfect  the  sound 
stocks  which  have  been  substituted  for  them. 

Remarks  on  Diseases  of  the  Vine. — We  may  be 
surprised  that  this  valuable  plant,  which  has  been 
so  carefully  cultivated  in  France,  should  be  attacked 
by  such  a  number  of  parasites,  both  animal  and 


42  MICROBES,  FERMENTS,  AND  MOULDS. 

vegetable.  Yet  we  should  rather  be  surprised  that 
the  vine  has  not  been  completely  destroyed  by  the 
combination  of  such  diverse  scourges,  and  that  it  has 
effectually  resisted  them  in  several  regions  of  France. 
When  we  consider  that  for  long  years  the  same  hoary 
old  stocks  have  been  required  to  produce  grapes 
without  truce  or  mercy,  and  often  without  taking 
pains  to  supply  to  them  by  a  fitting  manure  the 
nourishment  which  is  withdrawn  from  them  by  the 
fructification  of  the  grape,  we  shall  be  less  astonished 
at  the  decadence  of  our  vineyards.  And,  indeed, 
enlightened  minds  ascribe  the  attacks  of  these 
numerous  parasites  to  the  weakness  and  exhaustion 
of  our  vines,  rather  than  to  any  accidental  cause,  such 
as  an  importation  from  without. 

The  principal  remedy  may,  therefore,  be  found  in 
restoring  the  strength  of  the  vine  by  the  planting  of 
young  suckers,  and  still  more  of  seedlings.  Instead 
of  attempting  to  introduce  foreign  plants,  which  it 
may  not  be  easy  to  acclimatize,  and  which  will 
certainly  be  less  valuable  than  the  vines  we  have 
lost,  it  would  surely  be  better  to  seek  to  regenerate 
our  indigenous  kinds  by  crossing  the  cultivated  stocks 
with  wild  vines,  or  else,  as  Millardet  suggests,  by 
crossing  them  with  each  other.  The  attempt  might 
also  be  made  to  graft  the  stocks  from  Bordeaux  and 
Burgundy  on  wild  or  American  vines,  which  offer 
a  better  resistance  to  the  attacks  of  the  phylloxera. 


PARASITIC  FUNGI  AND  MOULDS.  43 


VI.  HABITAT  OF  PARASITIC  FUNGI:  THEIR  DESTRUC- 
TIVE ACTION. 

The  habitat  of  parasitic  fungi  is  extremely  varied. 
Roumeguere,  in  his  Cryptoyamie  ill&stre'e,  has  devoted 
more  than  forty  pages  of  a  large  quarto,  printed  in 
three  columns,  merely  to  the  enumeration  of  fungi, 
classified  according  to  their  position  in  plants,  animals, 
organic  or  inorganic  substances,  and  the  author  himself 
admits  that  this  list  is  far  from  complete. 

Parasitic  fungi  are  found  on  plants  belonging  to 
all  the  families  of  the  vegetable  kingdom,  and  also 
on  other  fungi ;  on  living  animals,  vertebrate  and 
invertebrate ;  on  their  dead  bodies  and  on  excrement ; 
in  stagnant  waters  and  in  the  sea,  on  piles  and  rocks. 
Others  prefer  marshes,  turf-bogs,  heathy  ground  (which 
may  be  marshy  or  dry),  dunes,  caves  and  holes,  and 
even  completely  covered  by  the  soil,  as  is  the  case 
with  truffles.  Others,  again,  grow  upon  stones,  walls, 
and  rocks ;  in  the  open  air  or  in  ruins ;  or,  like  Torula 
conylutinata,  and  Himantia  cellaria,  in  the  darkest 
caves,  where  they  form  a  species  of  feltwork,  often 
several  centimetres  in  thickness,  of  a  blackish  colour, 
ragged,  and  extremely  light,  which  in  the  course  of 
a  few  years  overspreads  the  walls  of  cellars.  Other 
fungi  inhabit  our  houses,  attack  our  food,  clothes, 
utensils  of  every  kind;  wall-papers  and  books,  of 
which  the  paste  offers  a  nutriment  which  they  can 


44  MICROBES,  FERMENTS,  AND  MOULDS. 

easily  assimilate ;  linen ;  and  even  our  toilet  sponges, 
notwithstanding  that  they  are  in  daily  use.  They 
may  even  be  found  on  the  most  powerful  chemical 
substances,  on  pastilles  of  sulphur,  arsenical  solu- 
tions, etc. 

"  The  general  belief,"  writes  Roumeguere,  "regards 
fungi  as  the  result  of  decomposition.  This  belief  is 
due  to  an  imperfect  acquaintance  with  the  nature  of 
these  plants.  Fungi  are  not  only  found  on  fragments 
of  wood  and  decayed  vegetables,  but  sometimes  even 
on  bare  pebbles,  on  glass,  on  window-panes,  on  the 
lenses  of  microscopes,  and  on  other  polished  surfaces. 
It  must  be  supposed  that  fungi  are  able  to  extract 
the  elements  of  nutrition  even  in  such  positions. 
Coprins,  which  have  a  surprising  power  of  develop- 
ment, grow  on  amputated  limbs.  Young  has  recorded 
the  appearance  of  a  great  number  of  these  fungi,  still 
in  an  imperfectly  developed  state,  below  the  mattress 
on  which  a  man  was  lying  whose  leg  had  been  ampu- 
tated. The  bed  was  cleaned,  and  in  nine  or  ten  days 
the  fungus  reappeared  in  the  same  abundance  as 
before.  Targionni-Tozetti  had  previously  observed  a 
similar  growth  on  the  apparatus  which  surrounded  a 
fractured  limb  in  St.  George's  Hospital,  Modena." 

Berkeley  states  that  immediately  after  the  death 
of  any  vegetable  substance,  an  army  of  fungi  of 
various  kinds  is  at  hand  to  complete  the  work  of 
decomposition.  The  soft  tissues  are  rapidly  reduced 
to  a  semi-fluid  condition  by  the  combined  action  of 


PARASITIC  FUNGI  AND  MOULDS.  45 

putrefaction  and  of  these  fungi.  The  hardest  wood 
yields  to  the  same  agents,  not  indeed  so  quickly,  yet 
much  more  rapidly  than  Would  be  the  case  from  the 
action  of  the  constituents  of  the  atmosphere  alone. 
When  a  log  of  one  of  our  finest  trees  is  attacked  by 
fungi,  it  soon  becomes  only  a  mass  of  rotten  wood, 
of  which  the  woody  tissue  has  been  traversed  and 
destroyed  by  the  mycelium.  If  the  same  log  were 
merely  subjected  to  the  action  of  the  weather,  it 
might  endure  for  half  a  century  before  becoming 
completely  rotten. 

Meruliua  destruena  (or  M.  lacrymans)  attacks 
beams  and  the  other  pieces  of  wood  used  in  building, 
and  rapidly  destroys  them.  The  administrators  of  the 
Canal  du  Midi,  Toulouse,  were  compelled  to  replace 
the  oak  piles  which  protect  the  sides  of  the  canal  as 
it  traverses  the  town,  on  account  of  the  ravages  of 
Dematium  giganteiim,  one  of  the  higher  orders  of 
fungi  in  its  early  form.  At  the  end  of  the  last 
century,  the  same  fungus  destroyed,  in  the  course  of 
two  or  three  years,  the  Foudroyant,  a  sixty-gun 
vessel. 

In  order  to  stop  the  development  of  these  fungi  in 
wood  used  for  building,  and  especially  in  wood  in- 
tended for  ship- building,  it  is  expedient,  as  soon  as 
the  trees  are  felled,  to  steep  them  in  a  metallic 
antiseptic  solution — as,  for  instance,  in  sulphate  of 
copper. 

An   experiment    made    by   Niigeli,   a    celebrated 


46 


MICROBES,  FERMENTS,  AND  MOULDS. 


botanist  in  Munich,  demonstrates  the  action  of  micro- 
scopic fungi  on  organic  substances,  exclusive  of  any 
previous  deterioration. 

"  I  enclosed,"  he  says,  "  seyeral  loaves  in  a  tin  case, 
which  was  carefully  but  not  hermetically  closed. 
When  the  case  was  opened  at  the  end  of  eighteen 
months,  the  loaves  were  reduced  to  a  small  mass, 
consisting  almost  entirely  of  filaments  of  mould,  in 
which  I  could  detect  no  trace  of  the  substance  of 
bread.  This  mass  was  soft  and  moist,  like  a  mud-pie. 
It  emitted  a  strong  odour  of  trimethylamin :  no  trace 
of  starch  remained.  One  hundred  parts  in  weight 
of  the  original  bread  were  transformed  into  sixty-four 
parts  in  their  moist  state,  and  seventeen  parts  after 
desiccation  in  the  open  air.  The 
starch  had  been  consumed  in  order 
to  form  carbonic  acid  and  water." 

Badham  sums  up  in  a  few 
words  the  destructive  effects  of 
microscopic  fungi.  "  Mucor  mu- 
cedo,"  he  writes,  "  devours  our  pre- 
serves; Ascophora  mucedo  turns 
our  bread  mouldy;  Molinia,  is 
nourished  at  the  expense  of  our 
fruits;  Mucor  herbarium  destroys 
the  herbaria  of  botanists;  and 
Chcetonium  chartatum  (Actino- 
spora)  develops  itself  on  paper,  on  the  insides  of  books, 
and  on  their  binding,  when  they  come  in  contact  with 


Fig.  19. — Chcetoniitm,  char- 
tatum, mould  on  paper. 


PARASITIC  FUNGI  AND  MOULDS.  47 

a  damp  wall  (Fig.  19).    When  beer  or  sweetmeats  turn 
sour,  it  is  the  work  of  a  fungus." 


VII.  PARASITIC  FUNGI  OF  INSECTS,  REGARDED  AS 
ALLIES  OF  MAN. 

Many  microscopic  fungi  attack  insects,  both  living 
and  dead.  We  have  all  seen  the  bodies 
of  flies  still  sticking  to  the  window- 
pane  or  curtain,  and  surrounded  by  a 
species  of  aureole  formed  by  the  growth 
of  a  fungus,  Penicttlium  racemosum,  ^yf 

an  aureole  of  Sapro- 

or  sometimes  Sporendonema  muscce  or 


Saproleynia  ferax,  of  the  family  of  Oospores  (Figs. 
20,  21,  22). 

Cordiceps  attacks  certain  caterpillars  of  the  genera 
Cossus  and  Hepialus,  when  they  are  buried  in  the 
sand  before  their  metamorphosis  into  chrysalides,  and 
kills  them  by  the  development  of  its  mycelium  in 
their  tissue.  These  caterpillars  may  often  be  found, 
bearing  on  their  backs  a  fungus  longer  than  them- 
selves (Fig.  23). 

Sphceria  militaris,  a  parasite  to  Bombyx  pityocarpa, 
the  caterpillar  found  on  pine-trees,  represents  one  of 
the  few  fungi  which  may  be  regarded  as  beneficial 
to  man,  since  it  destroys  multitudes  of  these  cater- 
pillars, and  thus  neutralizes  the  ravages  caused  by 
their  devouring  the  young  shoots  and  pine  needles. 
In  the  Antilles  there  is  a  wasp  called  the  vegetable 


48  MICEOBES,   FERMENTS,  AND  MOULDS. 

wasp,  because  it  is  attacked  during  its  lifetime  by 
a  fungus  which  it  carries  about  for  some  time,  and 
which  finally  causes  its  death :  this  is  Torrubia 
spherocephala  (Tulasne).  Isaria  sphingum,  another 


Fig.  21. — Two  filaments  of  Sapro-  Fig.  22. — Oogonium  of  Saprolegnia 

legnia  containing  spores  (greatly  surrounded  by  Antberidia  (much 

magnified).  magnified). 

species  of  the  same  genus,  has  been  observed  on  the 
back  of  a  butterfly,  which  was  poised  upon  a  leaf  as 
if  alive,  and  which  was  probably  killed  by  the 
development  of  the  fungus. 

These    and    other    facts,    not    to    speak    of   the 
muscardine  of  silkworms,  to  which  we  shall  return, 


PARASITIC  FUNGI  AND  MOULDS. 


49 


have  given  rise  to  a  surmise  that  if  we  could  discover 
the  parasitic  fungus  of  the  phylloxera,  we  might 
transform  it  into  a  powerful  auxiliary  of  agriculture, 
since  by  its  aid  the  parasitic  insect  which 
now  ravages  our  vineyards  might  be 
destroyed. 

From  this  point  of  view  Giard 
has  observed  several  of  these  parasites 
of  insects,  which  he  calls  Entomo- 
phthorece,  from  the  name  of  their  prin- 
cipal genus,  Entomophthora.  Such  is 
E.  Hraosa,  which  attacks  grasshop- 
pers and  the  diptera  of  the  genus 
Chironomus,  enveloping  them  in  a  thick 
feltwork  formed  by  the  winter  spores, 
and  speedily  killing  them.  In  the 
same  manner  Isaria  pulveracea  attacks  Pyrrhocoris 
aptei^us,  an  insect  which  is  often  injurious  to  our 
kitchen  gardens. 

It  has  been  asked  whether  Entomophthora  Plan- 
choni,  the  parasite  of  the  aphis,  might  not  also  prey 
upon  the  phylloxera,  but  the  experiments  made  in 
this  direction  have  not  hitherto  been  so  successful  as 
to  allow  us  to  count  on  this  means  of  averting  the 
scourge.  With  the  same  object,  Hagen  has  suggested 
the  use  of  beer-yeast,  which  seems  to  have  a  destruc- 
tive effect  on  insects,  as  it  is  developed  in  their  tissues. 


Fig.  23.—  Biittfrfly- 
nyin|ili  hearing  u 
(Jordicept. 


50  MICKOBES,   FERMENTS,   AND  MOULDS. 

VIII.  MUSCARDINE,  THE   DISEASE   OF   SILKWORMS. 

Muscardine,  which  is  caused  by  a  true  fungus, 
Botrytis  baesiana,  must  not  be  confounded  with  other 
diseases  which  attack  the  silkworm,  such,  for  instance, 
as  pebrin,  which,  as  Pasteur  asserts,  is  caused  by  a 
bacterium,  or,  strictly  speaking,  a  microbe,  and,  accord- 
ing to  the  recent  researches  of  Balbiani,  by  Psoro- 
spermia.  We  shall  presently  revert  to  this  disease. 

Botrytis  bassiana  is  a  true  mould,  belonging  to 
the  group  of  Oomycetes,  and  allied  to  the  potato- 
fungus,  Peronospora.  It  is  propagated  by  spores, 
which,  when  falling  on  a  silkworm,  germinate  and 
penetrate  its  body.  A  mycelium  is  then  developed, 
which  may  take  possession  of  the  whole  caterpillar 
without  appearing  externally.  The  germination  is 
rapid  in  proportion  to  the  age  of  the  silkworm. 

When  death  has  been  caused  by  the  develop- 
ment of  the  mycelium,  hyphae  appear  through  the 
animal's  skin ;  these  soon  bear  white,  chalky  spores, 
which  are  readily  detached  and  float  in  the  air  in  im- 
palpable dust  like  smoke.  The  silkworms  on  which 
the  dust  falls  do  not  appear  to  be  diseased,  and  eat 
with  avidity,  but  they  die  suddenly.  It  takes  from 
70  to  140  hours  to  develop  the  spores  and  spread 
the  contagion.  It  is  difficult  to  free  the  breeding- 
houses  from  all  the  silkworms  which  die  in  this 
manner;  those  which  die  after  having  crawled  up 
to  the  heather  to  prepare  for  their  transformation 


PAEASITIC  FUNGI  A.ND  MOULDS.  51 

into  chrysalides  are  only  thrown  away  when  they  are 
found  on  removing  the  cocoons.  The  clouds  of  dust 
dispersed  by  the  silkworms  perpetuate  the  disease 
in  the  best-ordered  factories.  When  the  heather  is 
thrown  out  of  window,  and  the  rooms  are  swept  to 
get  rid  of  the  dust,  the  spores  float  in  the  air  and 
are  dispersed  by  the  wind. 

Damp  favours  the  development  of  the  fungus,  and 
the  introduction  of  healthy  silkworms  into  an  infected 
breeding-house  will  not  extirpate  the  disease.  In  order 
to  attain  this  object,  it  is  necessary  to  get  rid  of  all 
the  dead  silkworms  before  the  development  of  the 
spores,  and  to  destroy  their  bodies  by  burning  them 
with  the  heather,  or  with  quicklime.  The  breeding- 
houses  should  then  be  completely  emptied,  and  the 
compartments  should  be  purified  and  disinfected  in 
the  ordinary  way  by  fumigation  with  sulphur,  and 
washed  with  chlorine  water,  before  fresh  silkworms  are 
placed  in  them. 

IX.   PARASITIC   FUNGI  OF  THE  SKIN  AND  Mucous 
MEMBRANE  OF  MEN  AND  ANIMALS. 

The  skin-diseases  of  man  and  animals  which  are 
termed  tinea  are  caused  by  the  presence  of  parasitic 
fungi,  just  as  the  itch  is  produced  by  the  presence 
of  animals  belonging  to  the  group  A  car  us.  These 
diseases  are  rendered  eminently  contagious  by  the 
dissemination  of  the  spores  of  these  fungi,  which  will 


52  MICROBES,  FERMENTS,  AND  MOULDS. 

germinate  wherever  the  conditions  of  heat  and  moisture 
are  favourable,  even  on  a  healthy  skin,  or  where  it  is 
only  irritated  by  a  simple  scratch. 

Ringworm,  Achorion  Schcenlenii,  the  fungus 
which  produces  this  disease  on  the  parts  of  the 
skin  covered  by  hair,  belongs  to  the  same  family  as 
oidium.  Its  mycelium  produces  hyphae,  bearing 
chaplets  of  spores,  as  in  the  Mucorinese,  but  there  is 
no  true  sporangium. 


Fig.  24. — Achonon  Schcenlenii,  fungus  of  ringworm  ( x  400  diam.) :  a,  spores ;  5,  chains 
of  spores ;  c,  mycelium. 

They  are  found  in  abundance  in  spots  of  ringworm, 
amidst  the  sulphur-coloured  substance  which  carpets 
them.  If  a  morsel  of  this  substance  is  dissolved  in 
ammonia,  the  fungus  is  detached,  and  may  be  observed 
under  the  microscope,  especially  if  care  has  been  taken 
to  stain  it  brown  by  an  aqueous  solution  of  iodine 
(Fig.  24). 


PARASITIC  FUXGI  AND   MOULDS. 


53 


The  mycelium  consists  of  elongated,  cylindrical 
articulations,  which  find  their  way  among  the  cells  of 
the  epidermis,  especially  in  the  vicinity  of  the  edges 
of  the  patch,  and  may  penetrate  deeply  into  the  dermis 
(Fig.  25).  Some  of  the  shorter  filaments  terminate  in 


Fig.  25.— Transverse  section  of 
b,  superficial  layer  of  dern 
spores. 


i  spot  of  ringworm  :  a,  epidermis ; 
tlie  dermis;  d  d' mycelium  with 


chaplets  of  spores,  which  are  successively  detached 
from  the  stem ;  they  are  therefore  found  detached  in 
large  numbers  in  the  midst  of  the  epidermic  cells. 
The  centre  of  the  patch  is  occupied  by  one  or  more  still 


54  MICROBES,   FERMENTS,  AND  MOULDS. 

infected  hairs,  surrounded  by  spores;  but,  while  the 
centre  is  in  process  of  healing,  the  fungus  extends  to 
the  periphery  and  continues  to  spread.  The  raised 
surface  of  the  patch  is  formed  by  this  parasitic  growth, 
which  forms  a  circular  excrescence,  always  increasing 
in  size,  while  raising  and  thickening  the  epidermis. 
The  parts  affected  by  the  mycelium  are  characterized 
by  a  slight  suppuration  throughout  the  patch ;  the 
indurated  tissue  is  gradually  absorbed,  leaving  deep 
scars  which  persist  after  a  cure  has  been  effected. 

The  mycelium  is  found  on  infected  hairs  between 
the  coats  of  their  bulbous  roots,  while  the  numerous 
spores  are  only  found  between  the  epidermic  layers  of 
the  hair. 

This  fungus  may  be  inoculated  in  all  parts  of  the 
skin,  but  its  favourite  site  is  the  head,  where  it  pro- 
duces the  disease  long  known  as  ringworm,  or  favus. 

It  has  been  already  said  that  fungi  prey  upon  each 
other.  Thus  Achorion  has  for  a  parasite  Pucciniafavi, 
a  minute  fungus  of  a  reddish-brown  colour,  which  is 
often  developed  on  the  whitish  epidermic  scales  which 
cover  the  mycelium  on  fresh  spots  of  ringworm.  The 
same  parasite  has  also  been  observed  on  Pityriasis. 

Trichophyton  tonsurans. — This  fungus,  allied  to 
the  preceding,  subsists  likewise  on  skin  covered  with 
hair,  and  produces  tinea  tonsurans. 

It  is  formed  of  a  mycelium  with  two  sorts  of 
hyphae,  some  simply  nutritive,  others  with  short 
articulations,  separating  into  chaplets  of  rounded 


PARASITIC  FUNGI  AND  MOULDS.       55 

spores,  which  are  continually  detached  (Fig.  26).    The 


Fig.  26.—  Trichnphyton  tonsurans  on  the  epidermic  layers  of  a  patch  of  circinnate 
herpes :  o,  spores ;  6,  mycelium  with  loiig  articulations ;  c,  mycelium  with  short 
articulations  (  x  400  diam.). 

mycelium  is  often  ramified,  and  penetrates  within  the 
epidermic    cells,  especially  at 
the  base  of  the  hairs. 

It  is  probably  that  the 
parasitic  Sycosis  which  affects 
the  beard,  and  circinnate 
herpes,  two  other  skin-diseases, 
are  only  varieties  of  the  same 
disease.  In  fact,  Cornil  and 
Ranvier  have  ascertained  that  if  Trichophyton  is  in- 
serted in  the  glabrous  chin  of  a  child,  it  will  produce 


Fig.  27. — Spores  and  filaments  of 
Trichophyton,  germinating  on 
two  epidermic  cells  of  the  skin. 


56  MICROBES,  FERMENTS,  AND  MOULDS. 

herpes;  and  that  parasitic  herpes  may  also  be  pro- 
duced on  the  back  of  the  hand  by  the  transference 
of  the  fungus  from  a  patch  of  Tinea  tonsurans. 

The  fungus  may  be  transmitted  to  cats,  dogs,  and 
horses,  who  thus  become  agents  of  the  contagion.  A 
fresh  study  of  the  disease  lias  been  recently  made  by 
an  Englishman,  Dr.  Thin,  and  he  also  regards  it  as 
identical  with  herpes,  or  Tinea  circinata. 

According  to  this  observer,  the  contagion  is  not 
transmitted  by  floating  spores,  but  only  by  direct 
contact,  and  especially  by  the  exchange  of  hats  and 
caps  so  common  among  school -children. 

Experiments  in  artificial  culture  in  milk,  carrot- 
juice,  or  aqueous  humour  show  that  the  fungus  cannot 
be  developed  when  the  hair  on  which  the  spores  are 
is  entirely  submerged ;  a  certain  degree  of  moisture  is, 
however,  necessary,  which  is  probably  more  frequently 
found  on  children's  heads.  In  adults,  the  bulbous  root 
of  the  hair  is  dryer  between  the  follicle  and  the  skin. 
The  parasite  may  be  destroyed  by  causing  an  inflam- 
mation of  the  part  affected,  since  the  serous  effusion 
thus  produced  places  the  hair  in  the  same  conditions 
as  in  the  culture-liquids  in  which  it  is  completely 
covered,  and  not  floating. 

Pityriasis  versicolor  is  produced  by  a  fungus 
resembling  the  foregoing,  termed  Microsporon  furfur. 
It  grows  between  the  cells  of  the  epidermis,  and 
effects  their  rapid  degeneration.  The  hyphse  have 
long  articulations,  intermixed  with  round  spores,  not 


PARASITIC  FUNGI  AND  MOULDS. 


57 


arranged    in    a    chaplet,    but    grouped     below    the 
epidermis  (Fig.  28).     The  development  is  very  slow, 


I 


\  ig.  2S.— Microspornn  furfur  :  a,  b,  groups  of  spores ;  c,  mycelium  with  lonjr  trans- 
parent,  and  curved  articulations. 

but  the  fact  of  its  inoculation  can  be  established,  and 
artificial  cultures  may  be  made. 

In  the  two  parasites  of  which  we  have  now  to  speak 


58  MICROBES,  FERMENTS,  AND  MOULDS. 

we  cannot  recognize  any  mycelium,  and  in  this  par- 
ticular they  are  allied  with  the  ferments,  of  which  we 
shall  speak  presently.  The  fungus  consists  of  round 
cells,  which  multiply  by  budding.  De  Lanessan 
regards  them  as  a  separate  group,  to  which  he  gives 
the  name  of  Microsporete,  while  he  designates  those 
parasites  of  skin  covered  with  hair  which  possess  a 
distinct  mycelium  under  the  name  of  Trichophyta. 
The  Pelade  Fungus. — Pelade  is  another  disease  of 


o 
Fig.  29. — Pelade  fungus :  epidermic  cells,  charged  with  spores  (  X  500  diam.). 

the  skin  covered  with  hair,  which  is  caused  by  Micro- 
sporon  Audouini,  and  which  presents  the  characters 
just  indicated.  It  would,  therefore,  be  an  error  to 
give  it  the  same  generic  name  as  Microsporon  furfur, 
a  fungus  of  which  the  mycelium  is  well  developed, 
if  the  recent  researches  of  Grawitz,  to  which  we 
shall  presently  return,*  did  not  tend  to  snow  that 
Microsporese  and  Trichophyta  are  only  forms  of  the 
same  parasite  in  different  phases. 

*  See  chapter  on  Polymorphism  of  Microbes. 


PARASITIC  FUNGI  AND  MOULDS. 


59 


The  pelade  fungus  develops  in  the  superficial 
horny  layer  of  the  epidermis,  on  the  surface  of  the 
epidermic  cells,  and  in  their  interstices.  It  does  not 
penetrate  the  hair-follicles,  and  is  only  occasionally 
found  on  the  hairs,  in  which  case  it  is  fastened  to  the 
detached  pellicles  of  the  epidermis,  not  to  the  interior 


4 

o 


£000 

«1 

o 


a  6 


42 
.ooO  O 


At      3 

£  o 


Fig.  30.— Hair  affected  by  the 
rapid  progress  of  Pelade 
decalvante.  It  is  surrounded 
by  epidermic  cells  charged 
with  spores  (x  208  diani.). 


Fig.  31. — Isolated  spores,  taken  from 
patches  of  pelade :  1,  2,  3,  4,  largo 
spores ;  5,  budding  spores ;  6,  7,  8, 
empty  spores ;  9  to  12,  small  spores 
(X  1000  diam.). 


of  the  hair  (Figs.  29,  30).  It  is  composed  entirely  of 
the  round  spores  already  described,  which  are  re- 
produced by  budding  (Fig.  31). 

The  Fungus  of  Pityriasis  capitis  simplex. — It  is 
very  similar  to  the  foregoing,  and  is  likewise  seated 


60 


MICROBES,   FERMENTS,  AND  MOULDS. 


in  the  horny  layer  of  the  epidermis,  on  which  it 
produces  a  roughness  in  the  form  of  dusty  pellicles. 
It  penetrates  the  hair-follicles,  but  not  deeply,  and 
only  in  the  vicinity  of  the  point  at  which  they  emerge. 
The  spores  of  which  it  entirely  consists  are  generally 
of  an  elongated  form,  and  give  off  buds. 

According  to  Mallassez,  this   fungus  is  the  prin- 
cipal  cause   of  alopecia;   that  is,   the    shedding    of 


o    o 


Fig.  32.— Epidermic  cell  of  okin 
covered  with  hair,  affected  by 
Pityriasis  simplex,  and  covered 
with  spores  (  x  1000  diam.). 


Fig.  33.— Isolated  spores,  taken 
from  pellicles  of  Pityriasis 
capitis  simplex:  a,  full  spores; 
b,  empty  spores ;  c.  full  spores 
budding  ;  d,  the  same  empty 
(  x  1000  diam.) 


hair,  and  the  baldness  which  eventually  ensues  from 
it.  It  acts  in  two  ways  :  (1) '  its  presence  and  multi- 
plication disintegrate  the  epithelial  layers;  (2)  the 
foreign  body  irritates  the  epidermis,  producing  exces- 
sive activity  in  the  evolution  of  cells,  and  consequently 
the  incessant  desquamation  which  is  the  most  apparent 
symptom  of  the  disease.  The  shedding  of  hair  is  chiefly 
due  to  obstruction  in  that  portion  of  the  hair-follicle 
which  underlies  the  orifice  of  the  sebaceous  glands,  and 


PARASITIC  FUNGI  AND  MOULDS.  61 

this  checks  the  regular  development  of  the  hair.  The 
consequent  irritation  of  the  follicle  produces  hyper- 
trophy; this  leads  to  the  shrinking  and  finally  to 
the  obliteration  of  the  follicle,  and  after  languishing 
for  a  while,  the  hair  falls  off. 

Thrush  (Oidium  albicans)* — This  fungus  generally 
appears  on  the  mucous  membrane  of  the  mouths  of 
infants,  especially  of  those  brought  up  by  hand,  and 
which  have  been  accustomed  to  the  use  of  a  sucker. 
The  saliva  becomes  acid,  and  the  white  spots  which 
constitute  thrush  (Fig.  34)  appear  in  several  places, 
especially  on  the  tongue,  the  gums,  and  the  soft 
palate. 

This  plant  is  composed  of  two  elements:  of  hyphse, 
and  of  spores,  which  adhere  closely  to  the  mucous 
membrane.  The  spores  become  elongated  and  con- 
verted into  hyphse,  which  are  segmented  and  ramified 
as  their  length  increases ;  and  they  produce  spores  by 
division  of  the  terminal  cell,  or  sometimes  by  endo- 
genous formation  within  the  hyphse. 

Thrush  sometimes  occurs  in  adults  in  certain 
diseases,  such  as  phthisis  and  typhoid  fever,  especially 
when  the  patient  eats  little  and  is  imperfectly 
nourished,  which  is  frequently  the  case  in  serious  or 
protracted  illness. 

It  is  easy  to  destroy  thrush  by  washing  the 
mouth  with  Vichy  water,  or  a  solution  of  bicarbonate 

*  Oidium  albicans,  Robin ;  Saccharomyces  attricans,  Recs ;  Sacch. 
mycoderma,  Grawitz.  (See  chapter  on  the  Polymorphism  of  Microbes.) 


62 


MICROBES,   FERMENTS,  AND  MOULDS. 


of  soda,  which  neutralizes  the  acidity  of  the  saliva. 
It  is,  above  all,  essential  that  the  feeding-bottle,  all 
the  utensils  employed  for  the  infant,  and  the  infant 
itself,  should  be  kept  perfectly  clean ;  and,  unfortu- 
nately, this  condition  is  too  rarely  fulfilled,  especially 


Fig.  34.— O'idium  albicans,or  Saccharomyces  mycoderma:  d,  much-branched  myce- 
lium ;  g,  chaplet  or  torula,  of  spores,  giving  birth  at/,  k  to  the  mycelium. 

among  the  working  classes  in  towns,  and  districts  in 
which  children  are  usually  put  out  to  nurse.  The 
feeding-bottle  in  use  in  such  cases  generally  smells 
so  sour  as  to  be  offensive  to  every  one  who  is  not 


PARASITIC  FUNGI  AND  MOULDS.  63 

accustomed  to  it,  and  under  these  conditions  thrush 
is  almost  certainly  developed,  so  that  few  children 
escape  an  attack.  It  is  not  generally  dangerous,  yet 
it  may,  in  some  cases,  compromise  the  health,  and 
even  cause  the  death  of  the  child.  In  addition  to  care 
about  cleanliness,  a  little  pinch  of  bicarbonate  of  soda 
may  be  put  in  the  feeding-bottle;  this  prevents  the 
milk  from  turning  sour. 

Onychomycosis. — This  disease,  which  attacks  the 
nails  of  men  and  the  hoofs  of  uni-ungulates  (the  horse, 
the  ass,  and  the  mule),  is  caused  by  a  parasitic  fungus 
of  the  genus  Achorion  (A.  keratophagus).  In  man  it 
is  termed  dry  caries,  and  it  is  a  fungus  which  is  readily 
transferred  from  man  to  the  animals  with  which  he 
has  to  do,  just  as  Achorion  Schwnlenii  of  ringworm 
passes  from  man  to  the  dog,  cat,  rat,  horse,  ox,  and 
perhaps  even  to  rabbits  and  gallinacese. 

In  uni-ungulates  the  fungus  is  introduced  into  the 
cracked  and  superficial  layer  of  the  hoof  through  its 
fissures.  In  order  to  destroy  it,  this  external  layer 
must  be  removed,  and  for  greater  security  an  anti- 
parasitic  treatment  should  be  used. 

This  remedy  cannot  be  applied  to  the  human  subject 
without  causing  considerable  pain ;  yet  the  nail  may 
be  pared  and  scraped,  and  the  anti-parasitic  remedy 
can  then  be  applied. 

Prevention  and  Cure  of  Skin-diseases. — The  general 
custom  of  going  to  a  common  barber  to  have  the  hair 
dressed  or  cut  must  conduce  to  the  dissemination  of 


64  MICROBES,  FERMENTS,   AND  MOULDS. 

the  fungi  which  attack  those  parts  of  the  skin  clothed 
with  hair ;  the  brush,  the  comb,  or  razor  which  passes 
successively  and  on  the  same  day  over  hundreds  of 
heads  or  chins  must  necessarily,  if  only  in  one  case 
out  of  ten,  carry  the  spores  of  the  parasite  from  one 
person  to  another. 

The  parasitic  diseases  of  the  hair  are  extremely 
persistent,  and  precautions  as  to  cleanliness  will  not 
always  effect  a  cure.  The  mixtures  sold  by  hair- 
dressers under  the  name  of  capillary  water,  lotion  to 
eradicate  scurf,  etc.,  should  all  be  rejected.  Experience 
shows  that  wetting  the  head  often  favours  the 
development  of  the  fungus,  which  may,  indeed,  remain 
stationary  for  two  or  three  days,  but  which  becomes 
more  vigorous  as  soon  as  the  head  is  dry.  Sulphur 
and  its  compounds  are  successful  in  such  cases,  as 
well  as  in  the  parasitic  diseases  of  plants.  It  would 
be  best  to  apply  this  remedy  in  the  form  of  a  dry, 
impalpable  powder,  as  in  the  application  of  sulphur 
to  the  vine,  but  this  cannot  be  done  without  in- 
conveniences to  which  the  persons  affected  do  not 
readily  submit ;  it  might,  however,  be  tried  by  those 
whose  hair  is  naturally  greasy.  In  other  cases,  and 
especially  in  those  in  which  the  hair  is  dry,  as  it 
usually  is  in  persons  affected  by  Pityriasis  capitis, 
pomades  must  be  used,  although  it  has  been  asserted, 
but  not  proved,  that  fatty  substances  afford  nourish- 
ment to  the  fungus. 

However  this  may  be,  the  pomade  for  which  we 


PARASITIC  FUNGI  AND  MOULDS.  65 

subjoin  the  recipe  has  been  very  successful  in  pity- 
riasis,  and  in  all  the  infantile  forms  of  ringworm, 
including  that  which  occurs  in  teething,  and  which 
may  be  safely  treated,  in  spite  of  prejudices  to  the 
contrary : 

Turbith  mineral  (tri-mercuric  sulphate) ...        1  to  2  grs. 
Benzoinated  lard         ...  ...  ...       15  grs. 

This  pomade  is  lemon-coloured ;  it  will  assume  a 
flesh-colour  by  the  addition  of  a  few  drops  of  red 
litmus,  and  may  be  scented  to  the  taste  of  the  person 
who  is  to  make  use  of  it.  In  ordinary  cases  of 
pityriasis,  it  need  only  be  applied  every  eight  or 
fifteen  days.  It  is  indispensable  to  wash  the  combs 
and  brushes  in  a  solution  of  potash  or  ammonia,  lest 
the  benefit  of  the  treatment  should  be  lost  by  re- 
infection. In  the  case  of  true  ringworm,  especially  in 
adults,  a  much  more  energetic  treatment  is  necessary, 
for  which  medical  advice  is  required. 


66  MICROBES,  FERMENTS,  AND  MOULDS. 


CHAPTER  II. 

FEEMENTS   AND  ARTIFICIAL  FERMENTATIONS. 

I.  WHAT  is  FERMENTATION? 

CHEMISTS  define  fermentation  in  these  words :  "  Fer- 
mentation takes  place  wherever  an  organic  compound 
undergoes  changes  of  composition,  under  the  influence 
of  a  nitrogenous  organic  substance  called  a  ferment, 
which  acts  in  small  quantities  and  yields  nothing  to 
the  fermented  substance  "  (A.  Gautier). 

This  nitrogenous  substance,  termed  a  ferment,  is 
regarded  by  naturalists  as  an  organized  living  being, 
either  animal  or  vegetable.  This  was  demonstrated 
by  the  researches  of  Cagnard  de  La  Tour,  of  Turpin, 
of  Dumas,  and  more  recently  by  the  splendid  achieve- 
ments of  Pasteur.  It  is  now  proved  that  the  artificial 
fermentation  which  takes  place  in  the  manufacture 
of  wine,  beer,  etc.,  is  produced  by  small  microscopic 
plants,  called  ferments  or  yeast. 

The  chemical  transformation  resulting  from  them 
might  be  obtained  without  the  intervention  of  yeast, 


FERMENTS  AND  ARTIFICIAL  FERMENTATIONS.      67 

properly  so  called,  either  by  means  of  a  nitrogenous 
substance  of  animal  origin  (Berthelot),  or  by  other 
chemical  and  physical  processes  which  we  shall 
presently  mention.  But  it  may  be  questioned  whether 
the  nitrogenous  substance  of  animal  origin,  which 
Berthelot  considers  to  be  dead,  does  not  contain  a 
living  ferment.  This  is  not  admitted  to  be  the  case 
by  Bechamp,  whose  theory  will  be  given  further  on. 

Whenever  fermentation  is  produced  solely  by  the 
influence  of  physical  and  chemical  agents,  the  action 
is  very  slow.  But  it  is,  on  the  other  hand,  very  rapid 
when  effected  by  living  ferments  or  yeast,  and  it  is 
also  much  less  costly,  so  that  the  latter  mode  of 
fermentation  is  preferred  by  manufacturers.  Yeast  is, 
therefore,  the  true  agent  in  artificial  fermentations. 

All  the  saccharine  liquids  which  contain  glucose  or 
grape  sugar,  or  a  sugar  which  can  be  transformed  into 
glucose,  and  also  all  nitrogenous  substances,  phos- 
phates, and  ammoniacal  salts,  produce  alcohol  at  a 
temperature  varying  between  25°  and  100°,  and  the 
yeast  of  beer  (of  which  the  spores  are  carried  through 
the  air)  appears  and  is  developed  at  the  same  time; 
this  occurs  in  the  juice  of  grapes,  beetroot,  sugar- 
cane, etc.  The  alcoholic  liquids  thus  produced  are 
then  subjected  to  distillation  in  order  to  extract  the 
alcohol.  The  transformation  of  alcohol  into  vinegar 
is  produced  by  another  ferment. 

Fermentations  are  very  common  in  nature.  The 
transformation  of  sugar  into  lactic,  butyric,  and 


68  MICROBES,   FERMENTS,  AND  MOULDS. 

caproic  acids,  under  the  influence  of  nitrogenous 
substances  and  of  the  air;  the  change  into  glucose 
of  gums,  of  starch,  of  dextrine,  of  sucrose,  and  mannite; 
the  transformation  of  these  substances  into  each  other 
under  the  influence  of  living  agents,  or  of  those 
belonging  to  a  living  organism;  the  transformation 
of  such  glucosides  as  populin,  salicin,  tannin,  etc., 
into  sugar,  or  into  neutral  or  acid  substances; — all 
these  phenomena  are  fermentations  (A.  Gautier). 

We  may  even  go  further.  The  germination  of 
seeds  and  the  ripening  of  fruit  are  accompanied  by 
phenomena  qf  the  same  order.  In  animals,  gastric, 
pancreatic,  and  intestinal  digestion,  together  with  other 
changes  connected  with  nutrition  and  assimilation 
which  take  place  in  the  blood  and  in  all  the  organs, 
may  be  considered  as  true  fermentations.  In  this  case 
the  cells  of  our  tissues  and  the  blood-corpuscles  play 
the  part  of  yeast  in  effecting  alcoholic  fermentations. 

Finally,  the  miasmatic,  virulent,  and  contagious 
diseases,  which  we  shall  study  in  another  chapter, 
are  also  caused  by  changes  in  the  blood  and  in  the 
other  fluids  of  the  system,  and  should  be  considered 
as  fermentations,  produced  by  minute  microscopic 
organisms  analogous  to  ferments,  and  which  are,  as 
we  shall  presently  show,  bacteria  or  microbes,  strictly 
so-called.  The  putrefaction  of  dead  bodies  is  also 
a  fermentation. 

We  shall,  in  this  place,  only  consider  the  fermen- 
tations which  are  used  in  manufactures. 


FERMENTS   AND  ARTIFICIAL   FERMENTATIONS.      69 

History. — The  precise  knowledge  of  the  nature  of 
fermentation  is  of  comparatively  recent  date.  The 
ancients,  indeed,  seem  to  have  had  an  idea,  however 
vague,  of  this  phenomenon,  which  was  in  their  case 
connected  with  the  erroneous  theory  of  spontaneous 
generation.  We  all  know  the  fable  of  the  bees,  born 
from  the  putrefying  body  of  a  slain  bull,  which  forms 
one  of  the  chief  episodes  of  the  Metamorphoses  of 
Ovid,  and  of  the  fourth  book  of  Virgil's  Georgics. 
Aristotle  says  that,  by  means  of  heat,  one  living  being 
may  have  its  birth  in  the  corruption  of  another.  .  .  . 
Fermentation  is,  in  fact,  always  accompanied  by  an 
evolution  of  heat.  The  same  idea  was  revived  in  the 
Middle  Ages,  and  during  the  Renaissance  by  alchemists 
and  physicians.  Van  Helmont,  who  lived  early  in 
the  seventeenth  century,  goes  so  far  as  to  say,  "  It  is 
true  that  a  ferment  is  sometimes  so  bold  and  enter- 
prising as  to  form  a  living  being.  In  this  way, 
lice,  maggots,  and  bugs,  our  associates  in  misery, 
have  their  birth,  either  within  our  bodies  or  in  our 
excrement.  You  need  only  close  up  a  vessel  full 
of  wheat  with  a  dirty  shirt,  and  you  will  see  rats 
engendered  in  it,  the  strange  product  of  the  smell 
of  wheat  and  of  the  animal  ferment  attached  to  the 
shirt." 

Beside  these  singularly  rash  and  purely  fanciful 
assertions,  which  show  that  imagination  was  allowed 
in  those  days  to  play  a  much  too  important  part 
in  natural  science,  we  find  a  theory  of  the  fermenta- 


70  MICROBES,   FERMENTS,   AND  MOULDS. 

tion  in  putrefying  bodies  which  would  not  be  rejected 
by  modern  naturalists  and  chemists. 

"After  death  .  .  .  the  foreign  ferments,  which  are 
always  intent  on  change,  are  borne  through  the  air 
and  introduce  corruption  into  dead  matter  ...  at 
least,  unless  the  flesh  is  combined  with  certain  sub- 
stances, such  as  sugar,  honey,  or  salt.  It  is,  therefore, 
these  ferments,  attacking  whatever  matter  is  deprived 
of  life,  which  disintegrate  and  prepare  it  to  receive  a 
new  soul  (or  fresh  life)." 

Linnaeus,  again,  says  that  "  a  certain  number  of 
diseases  result  from  animated,  invisible  particles,  which 
are  dispersed  through  the  air.  .  .  ."  Boerhave,  in  1693, 
distinguished  three  kinds  of  fermentation :  alcoholic, 
acetous,  and  putrefactive.  But  we  must  come  down 
to  the  beginning  of  this  century  in  order  to  find  more 
definite  ideas  respecting  the  organic  nature  of  ferments. 

In  1813,  a  chemist  called  Astier  asserted  that 
every  kind  of  germ  from  which  ferments  proceed  is 
carried  by  the  air;  that  this  ferment,  of  animal 
nature,  is  alive,  and  is  nourished  at  the  expense  of 
the  sugar,  and  hence  results  disturbance  of  the 
equilibrium  between  the  elements  of  sugar. 

Subsequently,  in  1837,  Cagnard  de  La  Tour  de- 
clared yeast  to  be  a  collection  of  globules  which  are 
multiplied  by  budding;  and  in  the  following  year 
Turpin  described  the  yeast  of  beer  as  a  vegetable, 
microscopic  organism,  which  he  termed  Torula  cere- 
visioe  (Fig.  35). 


FERMENTS  AND  ARTIFICIAL  FERMENTATIONS.     71 


Fig.  35.— Tor-ula  (Saccha- 
romyces)  cerevisia;,  yeast 
of  beer  (x  400  diam.). 


Chemists  were  at  first  unwilling  to  admit  the 
important  part  played  by  yeast  in  fermentations,  and 
in  order  to  explain  it,  they  assumed  the  existence 
of  a  very  obscure  physico-chemical 
phenomenon,  to  which  the  name 
of  catalysis,  or  action  by  presence, 
was  given.  But  in  1843  an  illus- 
trious French  chemist,  Dumas, 
clearly  explained  the  physiological 
function  of  the  living  ferment,  or 
yeast. 

" Fermentations,"  he  writes,  "are  always  pheno- 
mena of  the  same  order  as  those  which  characterize 
the  regular  accomplishment  of  the  acts  of  animal  life. 
They  take  possession  of  complex,  organic  substances, 
and  unmake  them  suddenly  or  by  degrees,  restoring 
them  to  the  inorganic  state.  Several  successive  fer- 
mentations are,  indeed,  often  required  to  produce  the 
total  effect.  The  ferment  appears  to  be  an  organized 
being  ;  .  .  .  the  part  played  by  the  ferment  is  played 
by  all  animals,  and  by  all  but  the  green  parts  of 
plants.  All  these  beings  and  organs  consume  organic 
substances,  multiply  and  restore  them  to  the  simplest 
forms  of  inorganic  chemistry." 

Finally,  Pasteur's  memorable  labours,  which  he 
began  to  publish  in  1857,  confirmed  the  new  theory 
of  fermentation,  which  no  one  now  doubts.  Pasteur 
states  that  every  fermentation  has  its  specific  ferment ; 
in  all  fermentations  in  which  the  presence  of  an  or- 


72  MICROBES,   FERMENTS,  AND  MOULDS. 

ganized  ferment  has  been  ascertained,  that  ferment  is 
necessary.  This  minute  being  produces  the  transforma- 
tion which  constitutes  fermentation  by  breathing  the 
oxygen  of  the  substance  to  be  fermented,  or  by  ap- 
propriating for  an  instant  the  whole  substance,  then 
destroying  it  by  what  may  be  termed  the  secretion 
of  the  fermented  products.  Three  things  are  necessary 
for  the  development  of  the  ferment:  nitrogen  in  a 
soluble  condition,  phosphoric  acid,  and  a  hydrocarbon 
capable  of  fermentation  (such  as  grape  sugar).  Finally, 
every  organized  ferment  of  fermentation  or  putrefac- 
tion is  borne  about  in  the  air,  as  may  be  shown  by 
experiments. 

II.  VEGETABLE  NATURE  OF  FERMENTS  OR  YEAST. 

Yeast,  or  ferments,  are  in  their  organization 
closely  allied  to  the  fungi  of  which  we  spoke  in  the 
preceding  chapter  under  the  name  of  Microsporon. 
Many  botanists  still  assign  them  to  the  class  of  fungi 
under  the  name  of  Saccharomycetes  ;  yet,  as  they  live 
in  liquids,  or  at  any  rate  on  damp  substances,  like  the 
Algae,  which  are  species  of  water-fungi,  it  is  now 
almost  agreed  to  place  them  in  the  same  category  as 
the  latter,  which  they  resemble  in  their  whole  organi- 
zation, except  in  the  absence  of  chlorophyl.  This 
last  characteristic,  the  only  one  by  which  they  ap- 
proximate to  fungi,  is  common  both  to  them  and  to 
microbes  or  bacteria,  which  are  only  ferments  of 


FERMENTS  AND  ARTIFICIAL  FERMENTATIONS.      73 

smaller  size,  and  which  are  now  also  placed  in  the 
class  of  Algae.  We  shall  return  to  this  subject  when 
we  come  to  speak  of  bacteria. 

The  structure  of  ferments  is  very  simple :  each 
plant  is  generally  composed  of  a  single  cell,  spherical, 
elliptical,  or  cylindrical,  formed  of  a  thin  cell- wall,  con- 
taining a  granular  substance  called  protoplasm,  which 
is  the  essential  part  of  the  plant.  These  cells  have  an 
average  diameter  of  ten  micro-millimetres.  They 
grow  and  bud,  and  when  one  of  them  reaches  a  certain 
size,  a  median  constriction  occurs ;  it  divides  into  two 
parts,  resembling  the  mother  cell,  and  these  some- 
times separate,  sometimes  remain  united  in  a  group 
or  chaplet  (Fig.  35).  This  mode  of  multiplication 
continues  as  long  as  the  plant  remains  in  a  liquid 
favourable  to  its  nutrition.  But  if  its  development  is 
hindered,  if,  for  example,  the  liquid  dries  up,  the  pro- 
toplasm contained  in  each  cell  contracts,  and  is 
transformed  into  one  or  more  globules,  which  are 
the  spores  or  endogenous  reproductive  organs  of  the 
plant.  These  spores  may  remain  undeveloped  for 
a  long  while,  may  become  perfectly  dry,  and  may 
even  be  subjected  to  a  very  high  temperature,  without 
losing  the  power  of  germination  when  they  are  again 
placed  in  conditions  favourable  to  their  development. 
They  then  reproduce  the  plant  from  which  they  had 
their  birth,  and  are  multiplied  in  the  same  manner.* 

*  For  further  details  ou  ferments  and  fermentations,  see 
Schutzeuberger's  work  on  the  subject. 


MICROBES,  FEKMENTS,   AND  MOULDS. 


III.  WINE  FERMENTS;  ALCOHOLIC  FERMENTATION. 

The  commonest  ferment  of  wine  is,  according  to 
Pasteur,  Saccharomyces  ellipsoideus  (Figs.  36,  37,  38), 
which  must  not  be  confounded  with  Kutzing's 
Cryptococcus  vini,  since  the  latter  has  nothing  to  do 


Fig.  36,—Saccliaromyces  ellipsoideus,  wine  ferment,  in  process  of  budding 
(X600  diam.). 

with  alcoholic  fermentation.     This  ferment  is  found 
on  the  grape,  and  is  thus  introduced  into  the  ferment- 


Fig.  3?.— Sacch.  ellipsoideus: 
development  of  spores  (x 
400  diam.). 


Fig.  38. — Sacch.  ellipsoideus: 
genuinationof  spores  (  x  400 
diam.). 


ing- vats.  The  adult  cells  are  of  an  elliptic  form,  and 
are  six  micro-millimetres  in  length,  by  four  or  five  in 
width.  They  bud,  and  are  reproduced  in  the  way 
already  indicated,  which  is  common  to  all  ferments. 


FERMENTS  AND  ARTIFICIAL  FERMENTATIONS.     75 

Sacch.  Pastorianus  (Rees)  is  probably  only  a 
variety  of  the  foregoing  (Fig.  39),  differing  a  little 
in  the  form  of  the  cells,  which  are  elongated,  pyriform, 
or  club-shaped. 

Lastly,  Sacch.  conglomerates  is  somewhat  rare.  It 
is  found  in  the  grape-must  when  fermentation  is 
nearly  over  (Fig.  40).  It  is  so  called  because  the  new 
cells  are  conglomerated,  instead  of  being  arranged  in 
a  chaplet. 

"We   must   now   notice  the  other  ferments  which 


Fig.  39.— Sacch.  Pastori-         Fig.  40.— Sacch.  conglam-      Fig.  41.— Sacch.  cxiguut 
anus  (  x.  400  dium.).  eratus  (  x  600  diam.).  (  X  350  diam.). 

are  found,  like  those  given  above,  in  fermented  syrups, 
and  which  may  also  produce  the  alcoholic  fermenta- 
tion of  wine.  Such  is  Sacch.  exiguus  (Fig.  41),  of 
which  the  cells  are  much  smaller  than  in  the  fore- 
going, since  they  are  only  three  micro-millimetres 
by  two  and  a  half  micro-millimetres. 

The  apiculate  ferment,  of  which  Engel  has  made 
a  separate  genus,  under  the  name  of  Garpozyma 
ipiculata,  is  the  alcoholic  ferment  which  appears  to 

the  most  widely  diffused  in  nature  (Fig.  42).  It 
found  on  all  kinds  of  fruit,  especially  upon  berries 
ind  drupes,  as  well  as  upon  most  of  the  fruit-musts 


76  MICROBES,   FERMENTS,   AND  MOULDS. 

which  are  in  process  of  fermentation.  It  has  likewise 
been  observed  in  Belgium  .upon  beer.  It  is  generally 
the  first  to  appear  and  bud  in  the  must.  Its  name  is 


Fig.  42. — Sacch.  apiculata  (Carpozyiaa),  iciuient  of  fruits  (  x  600  diam.). 

due  to  the  characteristic  form  of  its  cells,  which  are 
formed  like  rape-seed,  or  apiculated  at  both  extremi- 
ties of  their  large  axis. 

In  the  fermented  must  of  red  wine  we  find, 
together  with  Sacch.  ellipsoideus,  a  somewhat  dif- 
ferent form,  which  is  perhaps  only  a  variety — Sacch. 
Reesii. 

We  must  also  mention  another  alcoholic  ferment, 
Sacch.  mycoderma,  wine  or  beer  flowers,  which  con- 


Fig.  43. — Sacch.  mycoderma,  or  Fig.  44. — Different  forms  of  Sacch. 

wine-flowers  (  x  350  diam.).  mycoderma. 

stitute  the  white  pellicle  often  seen  on  bottled  wine 
(Figs.  43,  44).     Pasteur  has  shown  that,  under  certain 


FERMENTS  AND  ARTIFICIAL  FERMENTATIONS.      77 

circumstances,  Mycodemna,  vini  can  produce  alcoholic 
fermentation ;  this  is  easily  shown  by  adding  it  to  a 
saccharine  solution,  in  which  it  soon  produces  fermenta- 
tion. It  appears  on  the  surface  of  all  alcoholic  liquids 
which  are  exposed  to  the  air,  when  fermentation  is 
over  or  nearly  over.  Its  growth  is  very  rapid  ;  a  few 
cells  are  enough  to  cover  the  surface  in  the  course  of 
forty-eight  hours  with  a  thin  white  or  yellow  pel- 
licle, which  is  at  first  smooth,  and  then  wrinkled.  This 
implies,  according  to  Engel's  estimate,  that  a  single 
cell  has  produced  35,000  others  in  this  short  time. 

Most  of  these  different  forms  are  probably  only 
different  stages  of  development  of  a  limited  number 
of  species,  since  ferments  are  as  polymorphic  as 
microscopic  fungi. 

We  have  said  that  before  they  are  found  in  the 
must  of  wine  or  fruits,  the  ferments  fasten  in  a 
dormant  state  on  the  epidermis  of  the  fruit,  by  which 
means  they  are  introduced  into  the  liquid  about  to  be 
fermented.  We  see  how  the  spores  are  transported 
through  the  air  until  they  rest  on  the  downy  surface 
of  a  drupe  or  berry.  But  it  has  been  asked  what 
becomes  of  this  ferment  between  last  year's  vintage 
and  the  succeeding  summer,  and  in  what  way  it 
passes  the  winter. 

According  to  Hanson's  researches,  Sacch.  apiculata, 
which  is,  for  instance,  found  upon  gooseberries,  is 
washed  off  them  by  the  rain,  dispersed  by  the  wind, 
and  falls  to  the  ground  with  the  fruit,  where  it 


78  MICROBES,  FERMENTS,  AND  MOULDS. 

remains  buried  through  the  winter  as  a  dormant 
spore,  in  order  to  return  to  the  same  fruit  when  it 
has  ripened  in  summer.  It  can  only  be  borne 
through  the  air  when  the  ground  is  completely  dried. 

In  the  same  way,  the  ferments  of  wine,  after 
having  passed  through  the  bodies  of  men  and  animals, 
pass  the  winter  on  the  dungheap.  This  revelation 
may  not  be  pleasing  to  drunkards,  but  it  will  not 
surprise  those  who  are  acquainted  with  the  habits  of 
cryptogams  in  general,  and  of  fungi  in  particular. 
Brefeld  has  found  these  ferments  during  the  winter, 
especially  in  the  excrement  of  herbivorous  animals, 
and  on  the  dungheap. 

The  manufacture  of  wine  is  too  well  known  to 
require  description ;  we  need  only  remind  our  readers 
that  alcoholic  fermentation  essentially  consists  in  the 
transformation  of  glucose,  or  grape-sugar,  into  alcohol 
and  carbonic  acid.  The  latter,  given  off  in  the  form 
of  gas,  produces  the  ebullition  or  effervescence  which 
characterizes  fermentation,  and  to  which  its  name  is 
due.  Sugar  or  glucose  is,  therefore,  the  essential 
nutriment  of  all  yeast-plants,  and  the  indispensable 
element  of  these  fermentations,  of  cider,  beer,  and  all 
fermented  liquors,  as  well  as  of  wine. 

IV.  BEER- YEAST. 

The  yeast  of  beer,  or  Sacch.  cerevisice,  was  the 
earliest  known  and  the  most  carefully  observed  of 


FERMENTS  AND  ARTIFICIAL  FERMENTATIONS.     79 


all  the  ferments,  and  may  be  regarded  as  the  type  of 
the  family.  Its  cells  are  round  or  oval,  from  eight 
to  nine  micro-millimetres  in  their  longest  diameter, 
isolated  or  united  in  pairs  (Fig.  35). 

When  these  cells  are  deposited  in  a  saccharine 
liquid,  which  is  therefore  susceptible  to  fermentation, 
vesicular  swellings,  filled  with  protoplasm  at  the 
expense  of  the  mother  cell,  may  be  observed  at  one 


Fig.  45. — Yeast  of  superior  beer 
budding  (x  400  diaui.). 


Fig.  46.— Spores  of  beer-yeast,  in 
different  phases  of  development. 


or  two  parts  of  the  surface  of  the  cell ;  these  swellings 
increase,  acquire  the  size  of  the  mother  cell,  and  then 
contract  at  their  base  (Fig.  45).  They  generally  arise 
on  the  sides  of  the  cell,  more  rarely  on  its  extremities. 
The  new  cells  thus  formed  soon  separate  from  the 
mother  cell,  and  the  protoplasm  given  up  to  its  off- 
spring by  the  latter  is  replaced  by  one  or  two  empty 
spaces,  termed  vacuoles.  When  yeast  is  not  in  a 
liquid  susceptible  to  fermentation,  it  can  remain  for 
a  longer  or  shorter  time  without  modification.  If 
abruptly  deprived  of  all  nutriment,  and  especially  of 
sugar,  and  placed  in  a  sufficiently  moist  atmosphere, 


80  MICROBES,   FEEMENTS,   AND  MOULDS. 

spores  may  be  produced  (Fig.  46).  It  is  rather 
difficult  to  perform  the  experiment  with  success ;  the 
ferment  must  be  frequently  washed  with  distilled 
water,  as  it  may  otherwise  putrefy,  instead  of  fruc- 
tifying (Schutzenberger). 

Let  us  briefly  describe  the  process  by  which  the 
fermented  liquor  termed  beer  is  obtained.  The  barley 
which  constitutes  its  essential  principle  does  not 
contain  sugar ;  but  when  it  has  germinated  it  contains 
a  substance  termed  diastase,  under  the  influence  of 
which  the  starch  of  barley  can  be  converted  into 
glucose. 

The  barley,  which  has  been  moistened  in  order  to 
make  it  swell  and  germinate,  is  spread  in  a  thin  layer 
on  hurdles,  at  a  temperature  of  about  15°:  this  opera- 
tion is  called  malting.  It  is  generally  performed  in 
spring,  in  order  to  ensure  the  necessary  warmth 
and  moisture,  and  March  beer  is  considered  the  best. 
When  the  sprout  attains  to  two-thirds  of  the  length 
of  the  grain,  germination  is  arrested  by  drying  the 
grains  on  a  stove,  and  they  are  then  ground  to 
powder  and  become  malt.  This  malt  is  then  steeped 
in  water  at  the  temperature  of  60°  and  by  the 
action  of  the  diastase  the  starch  becomes  glucose. 
This  saccharine  fluid  or  wort  is  boiled  with  hops, 
which  are  now  added,  not  only  to  give  a  bitter  and 
aromatic  taste,  but  also  to  preserve  it.  This  infusion 
of  malt  and  hops  is  concentrated  and  cooled,  and  beer- 
yeast,  the  product  of  previous  operations,  is  added  in 


FERMENTS  AND  ARTIFICIAL  FERMENTATIONS.     81 


order  to  establish  fermentation.  The  yeast  is  procured 
by  collecting  the  scum  of  fermented  beer  and  straining 
it  into  bags. 

In  Belgium,  the  wort  is  allowed  to  stand  until  the 
spontaneous  development  of  fermentation  takes  place ; 
but  in  France  and  Germany  the  ferment  is  generally 
added.  In  this  case  two  methods  are  in  use,  fermenta- 
tion from  above,  and  fermentation  from  below ;  and  this 
enables  us  to  distinguish  two  kinds 
of  yeast,  that  of  superior,  and  that  of 
inferior  beer  (Figs.  45,  47). 

In  superior  beer,  the  saccharifica- 
tion  of  the  starch  of  malt  is  effected 
by  successive  steepings  in  casks  at 
the  relatively  high  temperature  of 
from  15°  to  18°.  As  the  yeast  is 
formed,  it  gradually  issues  from  the 
bung-holes  in  the  upper  part  of  the 
cask;  hence  its  name.  In  England,  large  open  vats 
are  used :  the  yeast  rises  to  the  top,  and  is  removed 
with  skimmers. 

In  the  manufacture  of  inferior  beer,  saccharifica- 
tion  is  effected  by  steeping  the  malt  in  open  vats  at 
the  lower  temperature  of  from  12°  to  14°.  The 
yeast  is  deposited  at  the  bottom  of  the  vats  in  a 
doughy  and  tenacious  mass.  When  the  first  and 
most  active  fermentation  is  at  an  end,  the  clear  liquid 
is  drawn  off  and  put  into  casks,  bottles,  or  pitchers, 
and  as  the  separation  of  the  yeast  is  not  yet  complete, 
6 


Fig.  47.— Yeast  of  in- 
ferior beer  in  process 
of  budding  (x  400 
diain.> 


82  MICROBES,  FERMENTS,  AND  MOULDS. 

it  continues  to  act  on  the  unmodified  sugar.  The 
production  of  fresh  yeast  makes  the  liquor  thick,  and 
the  amount  of  alcohol  and  of  carbonic  acid  increases 
in  accordance  with  the  time  for  which  it  is  kept,  after 
being  bottled  or  put  in  closed  casks. 

The  manufacture  of  most  fermented  liquors 
resembles  that  of  wine  or  beer ;  that  of  cider  is  very 
simple,  and  consequently  approximates  to  the  manu- 
facture of  wine.  The  apples  are  cut  and  crushed,  and 
remain  in  the  vats  until  fermentation  is  over;  the 
liquid  is  then  separated  from  the  solid  residue,  and 
put  into  casks  or  bottles. 


V.  CONCERNING  SOME  OTHER  FERMENTED  LIQUORS. 

There  are  many  other  fermented  liquors  made  in 
various  countries  with  substances  derived  from  the 
animal  or  vegetable  kingdom. 

In  France,  cider  or  perry  is  sometimes  made  from 
pears  or  crab-apples. 

What  the  French  call  boissons  are  cheap  fermented 
liquors,  prepared  from  dried  raisins  or  aromatic  sub- 
stances, such  as  the  dried  fruit  of  the  coriander,  to 
which  water  sweetened  with  treacle  is  added.  Fer- 
mentation is  usually  effected  by  germs  borne  by  the 
air,  or  by  those  introduced  by  the  coriander  and  the 
other  ingredients  of  the  liquor ;  or  it  may  be  hastened, 
as  in  Belgian  beer,  by  the  addition  of  beer-yeast  or 
baker's  yeast.  It  is  effected  by  the  transformation  of 


FERMENTS  AND  ARTIFICIAL  FERMENTATIONS.     83 

the  sugar  into  alcohol  and  carbonic  acid,  and  this  con- 
stitutes an  aerated  drink,  which  is  very  agreeable  when 
well  made,  and  especially  if  it  has  been  carefully 
bottled  before  fermentation  is  over. 

Koumiss  is  made  of  soured  and  fermented  mare's 
milk,  and  is  much  used  in  Russia  as  a  refreshing 
drink,  from  which  an  alcoholic  liquor  may  be  distilled. 

Many  kinds  of  brandy  are  made  from  the  fruits 
and  seeds  of  different  plants.  Kirschwasser  is  the 
alcohol  produced  by  distilling  cherries  or  geans ;  rum 
is  made  from  sugar-cane,  arrack  from  rice.  Gin, 
distilled  from  the  juniper-berry,  is  largely  consumed 
by  the  labouring  classes  in  England,  as  corn-brandy  is 
in  the  French  drinking-shops. 

The  savage  Malay  and  Polynesian  races  prepare 
fermented  liquors  from  the  sap  of  various  plants. 
Such  is  kava,  made  from  masticated  roots,  and  steeped 
in  an  infusion  of  Piper  methysticum.  In  this  case, 
the  ptzalin,  a  ferment  contained  in  the  human 
saliva,  transforms  the  fecula  into  a  sugar  susceptible 
to  fermentation.  The  operators  sit  round  a  large 
vessel  containing  the  roots  steeped  in  water,  and  each 
man  takes  a  piece,  which  he  masticates  conscientiously 
until  it  is  sufficiently  impregnated  with  the  salivary 
ferment.  This  process  is  revolting  to  our  ideas,  and 
few  Europeans  would  touch  a  liquor  which  has  been 
prepared  in  such  a  way ;  but  this  is  doubtless  an 
educated  prejudice  which  would  not  occur  to  a  native 
of  Oceana. 


84  MICROBES,   FEEMENTS,  AND  MOULDS. 

The  dragon-trees  (Draccena  termmalis  and  D. 
Aiistralis)  also  possess  a  feculent  root,  from  which  a 
fermented  liquor  is  extracted  in  the  same  manner  by 
the  Sandwich  Islanders. 


VI.  THE  LEAVEN  OF  BREAD. 

Bread  is  leavened  in  order  to  make  it  porous  and 
more  digestible.  According  to  Engel,  the  microbe  of 
baker's  yeast  is  Sacch.  minor,  resembling  that  of  beer- 
yeast,  only  more  minute.  Most  of  the  yeasts  which 
we  have  examined  contain  a  great  variety  of  microbes. 
However  this  may  be,  the  fermentation  of  bread,  like 
other  fermentations,  sets  free  carbonic  acid  gas,  and 
this  raises  the  dough  and  makes  it  light. 


CHAPTER  III. 

MICROBES,  STRICTLY  SO  CALLED,  OR  BACTERIA. 

I.  THE  VEGETABLE  NATURE  OF  MICROBES. 

As  we  have  seen  in  the  preceding  chapter,  there  is 
no  well-defined  limit  between  ferments  and  bacteria, 
any  more  than  between  ferments  and  fungi,  or,  again, 
between  fungi  and  bacteria.  Their  smaller  size  is  the 
principal  difference  which  separates  bacteria  from 
ferments,  since  in  other  respects  these  two  classes  are 
for  the  most  part  alike  in  form  and  organization.  There 
are  bacteria  of  large  size,  such  as  Leptothrix  buccalis, 
so  frequently  found  in  the  mouth  even  of  a  healthy 
man,  which  much  resembles  in  its  mode  of  growth 
some  of  the  lower  fungi,  such  as  Oidium  albicans. 
Yet  the  latter  is  regarded  as  a  fungus,  and  the  former 
as  an  alga,  by  our  best  cryptogamous  botanists.  It 
may,  however,  be  said  that  the  two  classes  of  algae  and 
fungi  are  connected  with  each  other  by  their  lower 
forms,  and  probably  have  a  common  origin  ;  just  as  the 
two  great  organic  kingdoms  are  connected  by  their 


86  MICEOBES,   FEEMENTS,  AND  MOULDS. 

lower  forms,  which  have  been  by  some  united  in  the 
kingdom  Protista. 

Microbes,  or  bacteria  (Schizophyta  or  Sddzomycetes) , 
appear,  in  liquids  examined  under  the  microscope,  as 
small  cells  of  a  spherical,  oval,  or  cjdindrical  shape, 
sometimes  detached,  sometimes  united  in  pairs,  or 
in  articulated  chains  and  chaplets  (Fig. 
48).  The  diameter  of  the  largest  of  these 
cells  is  two  micro-millimetres,  and  that 
of  the  smallest  is  a  fourth  of  that  size, 
.  so  that  at  least  500  of  the  former  and 

Fig.  48. — Ferment 

cLlrmf  aceti\  2000  of  tne  latter  must  be  placed  end 
fer°eninformesdioff  to  end  in  order  to  attain  the  length  of 
edor [na'charTets  a  millimetre.  It  is  therefore  plain  that  a 
fled).  magnifying  power  of  500  to  1000  dia- 

meters, or  even  still  higher,  is  required  to  make  these 
beings  clearly  visible  under  the  microscope. 

One  very  common  bacterium  may  be  found  every- 
where, and  can  be  easily  procured  for  microscopic 
observation :  Bacterium  termo,  or  the  microbe  of  im- 
pure water.  This  bacterium  is  not  injurious  to  health, 
since  there  is  no  potable  water  in  which  it  is  not 
found  in  greater  or  less  quantity.  In  order  to  obtain 
numerous  specimens,  it  is  enough  to  take  half  a  glass 
of  ordinary  water  from  a  spring  or  river,  and  to  leave 
it  for  some  days  on  a  table  or  chimney-piece,  the 
vessel  being  uncovered  to  allow  the  access  of  air.  We 
may  soon  observe  that  a  thin  coating  is  formed  on 
the  surface  of  the  water,  which  looks  like  a  deposit 


MICROBES,   OR  BACTERIA.  87 

of  fine  dust ;  this  dust  consists  of  myriads  of  bacteria. 
If  we  take  a  drop  of  this  water  and  place  it  under 
a  cover-glass,  in  order  to  examine  it  under  a  micro- 
scope with  a  magnifying  power  of  about  500  dia- 
meters, we  shall,  as  soon  as  the  instrument  is  properly 
focussed,  see  a  really  surprising  spectacle. 

The  whole  field  of  the  microscope  is  in  motion; 
hundreds  of  bacteria,  resembling  minute  transparent 
worms,  are  swimming  in  every  direction  with  an  un- 


4 


,          v 

r  // 

Fig.  49.— Bact.  termo  in  different  stages  of  development,  a-h  (much  magnified ). 


dulatory  motion  like  that  of  an  eel  or  snake.  Some 
are  detached,  others  united  in  pairs,  others  in  chains 
or  chaplets  or  cylindrical  rods  which  are  partitioned 
or  articulated  (Fig.  49) ;  these  are  only  less  mature  or 
younger  than  the  first.  Finally,  we  see  a  multitude  of 
small  globules  which  result  from  the  rupture  of  the 
chaplets.  All  these  forms  represent  the  different 
transformations  of  Bacterium  termo,  or  the  microbe  of 


88  MICROBES,  FERMENTS,  AND  MOULDS. 

putrefaction.  Those  which  are  dead  appear  as  small, 
rigid,  and  immovable  rods. 

In  observing  the  lively  movements  of  these  minute 
organisms,  we  might  be  tempted  to  regard  them  as 
animals.  But  we  know  that  movement,  taken  by 
itself,  is  not  peculiar  to  the  animal  kingdom.  Setting 
aside  the  movement  which  can  be  provoked  in  the 
mimosa  and  in  many  higher  plants,  it  is  well  to 
remember  that  many  of  the  lower  plants  are  capable 
of  motion :  this  is  the  case  with  Diatomacece,  in  which 
the  presence  of  chlorophyl  incontestably  proves  their 
vegetable  nature.  The  spores  of  plants  of  a  much 
higher  organization,  such  as  ferns  and  mosses,  have  the 
power  of  swimming  in  the  water,  just  as  bacteria  have : 
this  has  procured  for  them  the  name  of  Zoospores, 
although  many  of  them  contain  chlorophyl. 

The  movements  of  bacteria  are,  like  those  of  zoo- 
spores,  due  to  the  presence  of  vibrating  cilia,  which 
are  inserted  at  both  extremities,  or  only  at  the  hinder 
extremity  of  the  microbe,  and  which  form  organs  of 
propulsion  analogous  to  the  tails  of  tadpoles.  These 
organs  are  very  transparent  and  are  difficult  to  see  in 
the  living  subject,  even  with  the  strongest  magnifying 
power,  on  account  of  the  rapidity  of  their  movements. 
But  their  existence  has  been  ascertained  by  the  use  of 
staining  fluids-,  and  above  all  by  micro-photography. 

If,  however,  we  analyze  the  mode  of  motion  in 
Bacterium  termo,  and  compare  it  with  the  movements 
of  the  ciliated  or  flagellated  infusoria  which  may  often 


MICROBES,   OR  BACTERIA.  89 

be  seen  swimming  with  it  in  the  field  of  the  microscope, 
we  are  struck  by  the  difference.  Infusoria  come  and 
go,  swiftly  or  slowly — they  go  back  or  move  to  the 
right  or  left ;  in  a  word,  their  movements  seem  to  be 
actuated  in  some  sense  by  will.  Nothing  like  this 
is  observed  in  the  bacterium.  The  undulatory  move- 
ment by  which  it  is  animated  is  always  the  same,  and 
impels  it  straightforward,  like  a  stone  sent  from  a 
sling ;  it  never  voluntarily  goes  back  nor  out  of  its 
course,  but  only  under  the  influence  of  a  foreign  im- 
pulse, such  as  contact  with  another  bacterium,  when  it 
rebounds,  just  as  a  projectile  may  rebound  from  a  wall. 
On  encountering  an  obstacle,  the  bacterium  remains 
indefinitely  undulating  before  it,  without  ever  pausing 
or  showing  signs  of  fatigue,  until  some  external  cause 
comes  to  release  and  send  it  to  the  right  or  left.  We 
may  often  see  a  tangled  mass  of  bacteria,  perhaps 
adhering  by  their  cilia  or  by  some  other  substance,  in 
which  all  the  individuals  continue  to  undulate  until 
the  rupture  of  the  mass  permits  them  to  depart  in  all 
directions.  These  organisms  are  therefore  plants  in  the 
character  of  their  movements,  as  well  as  in  the  rest  of 
their  organization. 

In  bacteria  each  cell  consists  of  a  cellulose  wall, 
containing  protoplasm,  as  we  saw  was  the  case  in  fer- 
ments. The  multiplication  by  fission  is  effected  in 
precisely  the  same  way  in  bacteria  and  ferments,  and 
so  also  is  the  formation  of  spores.  Under  certain 
circumstances,  when  the  liquid  on  which  they  subsist 


90  MICROBES,   FEKMENTS,  AND  MOULDS. 

is  dried  up,  the  protoplasm  contracts  and  forms  spores, 
which,  when  set  at  liberty  by  the  rupture  of  the  cell- 
wall,  germinate  and  give  birth  to  fresh  bacteria.  The 
only  difference  consists  in  the  fact  that  ferments  may 
produce  several  spores  in  each  cell,  while  bacteria 
never  produce  more  than  one. 

Bacteria  were,  as  we  have  already  said,  for  a  long 
while  classed  with  fungi  under  the  name  Schizomycetes. 
But  recent  researches  into  their  organization,  and  more 
especially  into  their  mode  of  reproduction,  show  that 
they  resemble  a  group  of  inferior  algse  termed  Phy- 
cochromycece,  which  includes  Oscillaria,  Nostocs,  and 
Chroococcus,  species  generally  furnished  with  chloro- 
phyl.  Bacteria  represent  a  similar  group  devoid  of 
chlorophyl.  Zopf,  in  a  treatise  recently  published,  goes 
still  further :  he  asserts  that  the  same  species  of  alga 
may  at  one  time  be  presented  in  the  form  of  a  plant 
living  freely  in  water  or  damp  ground  by  means  of 
chlorophyllaceous  protoplasm,  and  at  another  in  the 
form  of  a  bacterium  or  parasitic  microbe,  devoid  of 
chlorophyl,  and  nourished  at  the  expense  of  organic 
substances  which  have  been  previously  elaborated  by 
animals  or  plants,  thus  accommodating  itself,  accord- 
ing to  circumstances,  to  two  very  different  modes  of 
existence. 


MICROBES,  OB  BACTERIA.          91 


II.  CLASSIFICATION  OF  MICROBES,  OR  BACTERIA. 

It  is  very  difficult  to  make  any  natural  classifica- 
tion of  the  organisms  which  belong  to  the  group  of 
microbes ;  we  have,  in  fact,  seen  that  they  only  differ 
from  each  other  in  external  form,  and  that  these  forms 
are  very  variable,  since  the  same  organism  may  present 
itself  successively  as  an  isolated  globule,  a  chaplet,  a 
chain,  and  a  more  or  less  articulated  rod  Microbes  are 
essentially  polymorphous,  and  adapt  themselves  to 
varied  conditions  of  existence,  which  influence  the 
form  taken  by  these  microscopic  organisms.  For  this 
reason  their  classification  has  often  varied,  their  dis- 
tinction into  genera  and  species  does  not  yet  rely  on 
precise  data,  and  the  opinions  formed  by  various 
authors  in  accordance  with  their  personal  researches 
still  differ  widely. 

We  will,  however,  subjoin  Wunsche's  classification. 

Schizophyta,  or  Schizomycetes. 

A.  Division  of  cells  always  occurring  in  the  same  direc- 
tion, so  as  to  form  a  chaplet  before  the  joiuts 
or  members  separate. 

1.  Cells  united  in  mucilaginous  or  gelatinous  families. 
o.  Cells  united  (in  a  state  of  repose)  in  amorphous 

families. 

a.  Spherical  or  elliptic  cells,  colourless  and  gene- 
rally motionless ...         ...         ...         Micrococcux. 

j8.  Cells  elongated  in  short,  movable  rods  ...  Bacterium. 

6.  Cells  united  in  families  with  sharp  outlines,  lobu- 

lated  and  agglutinated  like  frog-spawn       ...  Ascococcus. 

2.  Cells  arranged  in  filaments. 


92  MICROBES,  FERMENTS,  AND  MOULDS. 

a.  Cylindrical  filaments,  indistinctly  articulated,  mo- 

tionless. 
a.  Unramified,  very  slender  filaments : 

(1)  Short Bacillus. 

(2)  Long     Leptothrix. 

£.  Filaments  repeatedly  bifurcated  (false  ramifi- 
cations)   Cladothrix. 

b.  Spiral,  movable  filaments: 

(1)  Short,  faintly  undulated Spirochcete. 

(2)  Long,  flexible Vibrio. 

(3)  Short,  rigid      Spirillum. 

(4)  Rolled  into  mucilaginous  mass         Myconostoc 

B.  Cells  dividing  cross-wise,  and  the  daughter  cells  re- 
maining united,  like  packets  tied  with  a  crossed 

cord          Sarcina. 

Most  of  the  microbes  of  which  we  have  now  to  speak 
may  be  assigned  to  one  or  other  of  the  genera  given  in 
this  scientific  enumeration,  and  sometimes,  on  account 
of  their  polymorphism,  to  several  of  these  genera. 

Before  making  a  more  detailed  study  of  some  of 

them,  it  may  be  interesting  to  glance  at  them  as  a 

whole,  following  the  order  of  classification  given  above. 

The    genus    Micrococcus    (Hallier)    includes    the 

spherical  microbes,  which  are  the  most  common  and 

the  most  widely  diffused,  probably  because  the  spores 

^  and  early  stages  of  all  the  other  forms 

>p>°"a        have  this  spherical  shape  before  be- 

*  °  cSr/l  •         coming  elongated  and  assuming  their 

*     ;v  •          adult  form  (Fig.  50). 

rig.    so. -Microbes  Tnis   genus  is   divided   into  two 

crocoJus\^^.    sections:    the   first    includes   Micro- 

coccus  chromogenis,  i.e.  fabricators  of 

colouring  matter — an  extremely  interesting  group,  on 


MICROBES,   OR  BACTERIA.  93 

which  we  must  say  a  few  words,  since  these  microbes 
play  an  important  part  in  nature,  connected  with 
hygiene  and  domestic  economy ;  the  second  section 
includes  Micrococcus  pathogenis,  or  the  producers  of 
disease,  which  must  detain  us  longer. 

The  genus  Bacterium,  of  which  the  name  indicates 
that  it  is  rod-shaped,  also  includes  some  coloured 
species  and  more  which  are  colourless,  such  as  the 
bacteria  of  putrefaction,  of  stagnant  waters,  of  vegetable 
infusions,  etc.  (Fig.  49). 

The  genus  Ascococcus  is  less  common.  The  cells, 
united  in  groups  or  families,  form  mucilaginous, 
wrinkled  membranes  on  the  surface  of  putrefying 
liquids,  on  the  juice  of  meat,  on  the  infusion  of 
hay,  etc. 

Bacillus  (or  Bacteridice,  Davaine)  forms  an  ex- 
tremely important  genus,  characterized  by  its  long, 
flexible,  and  articulated  filaments ;  this  genus  includes 
the  butyric  ferment,  and  the  microbe  which  produces 
the  disease  called  anthrax,  or  splenic  fever. 

Leptothrix  buccalis  is  found  in  the  human  saliva 
and  between  the  teeth  (Fig.  51,  k). 

Cladothrix  dichotoma  forms  a  kind  of  fine  grass, 
which  appears  like  a  whitish  mucilage  on  the  surface 
of  putrefying  liquids  (Fig.  51,  p). 

Vibrio  rugula  and  V.  serpens  are  found  in 
infusions  in  the  form  of  tolerably  thick  filaments, 
which  have  only  one  inflection,  while  their  successors 

spirally  curved  (Fig.  51,  I). 


94  MICROBES,  FERMENTS,   AND  MOULDS. 

Spirillum  and  Spirochoete  only  differ  from  each 
other  in  the  number  and  approximation  of  their 
spirals.  Spirochcete  Obermeieri  is  found  in  the  blood 
of  those  affected  by  recurrent  fever;  S.  plicatile, 
which  is  found  in  stagnant  water,  amid  Oscillaria,  is 


Fig.  51. — Different  forms  of  microbes,  or  bacteria:  a,  b,  c,  d,  Jffcrococcus  of  various 
forms ;  e,  the  short  Bacterium ;  f,  the  short  Bacillus ;  k,  Leptothrix  or  long 
bacillus:  I,  Vibrio,  dividing  by  fission;  m,  Spirillum;  o,  Spirochcete;  p,  Clado- 
thrfo,  etc.  (from  Zopf :  highly  magnified). 

perhaps  only  the  parasitic  form  of  those  algae,  and 
has  often  been  regarded  as  the  cause  of  marsh  fever. 
Spirillum  is  also  found  in  infusions  (Fig.  51,  m,  o). 

Finally,  Sarcina  ventriculi,  so  different  in  form 
from  other  microbes,  is  found  in  the  fluids  of  the 
human  stomach,  in  the  blood,  and  in  the  lungs,  in  the 


MICKOBES,   OR  BACTERIA. 


95 


form  of  yellow  patches.     It  is  also  found  in  the  albu- 
men of  boiled  eggs,  in  potatoes,  etc.  (Fig.  52). 


Fig.  62.— Sarcina  ventriculi,  in  different  degrees  of  development 
(strongly  magnified). 


III.  THE  MICROBE  OF  VINEGAR,  AND  ACETIC 
FERMENTATION. 

Pasteur  has  shown  that  the  acid  fermentation  of 
alcoholic  liquids  is  due  to  the  existence  of  a  special 
microbe,  acting  like  a  ferment,  which  is  developed  on 
the  surface  of  fermented  liquors  whenever  they  are 
abandoned  to  the  contact  of  the  air,  in  the  presence  of 
albuminoid  substances.  This  microbe,  which  consti- 
tutes the  mother  of  vinegar,  and  which  is  termed 
Mycoderma  aceti,  is  probably  identical  with  Bacterium 
lineola,  so  often  present  in  infusions,  in  stagnant 
pools,  and  even  in  spring  water.  It  is  a  true 
bacterium  (Fig.  48). 

The  membrane  which  may  be  observed  on  the 
surface  of  liquids  in  course  of  acetic  .fermentation  is 
formed  of  very  minute  elongated  cells,  from  1*5  to  3 
micro-millimetres  in  length,  united  in  the  form  of 


96  MICEOBES,   FERMENTS,  AND  MOULDS. 

chains  or  curved  rods.  They  multiply  by  the  trans- 
verse fission  of  the  cell,  a  fission  preceded  by  a  median 
constriction.  These  are  characteristics  of  the  bac- 
terium, strictly  so  called. 

The  nutrition  of  this  microbe  resembles  that  oi 
beer-yeast :  it  requires  mineral  salts,  phosphates  of  the 
alkaline  metals  and  of  the  metals  of  the  alkaline 
earths,  proteid  matters,  or  ammoniacal  salts. 

This  ferment  is  an  oxidizing  ferment,  which  with- 
draws oxygen  from  the  air  and  transfers  it  to  the 
alcohol,  thus  converting  it  into  acetic  acid ;  hence  it 
can  only  subsist  in  contact  with  the  air,  and  perishes 
when  it  is  submerged,  so  that  acetification  is  then 
arrested.  The  oxidizing  power  of  this  microbe  is 
such  that  it  can  even  oxidize  alcohol  and  transform  it 
into  carbonic  acid  gas — a  fact  which  explains  how  the 
strength  of  wine  is  lowered  by  the  other  and  larger 
species,  Mycoderma  vini,  of  which  we  have  given  an 
illustration  (Figs.  43,  44).  This  action  is  less  lively 
in  the  presence  of  a  considerable  quantity  of  vinegar, 
and  at  Orleans  acetification  is  always  effected  in  vats 
which  contain  a  large  amount. 

What  is  called  the  Orleans  process,  which  is  the 
one  generally  employed  in  France,  consists  in  filling 
tuns  which  can  hold  about  200  litres  with  100  litres 
of  vinegar  and  10  litres  of  white  or  red  wine ;  once  a 
week  10  litres  of  vinegar  are  drawn  off,  and  replaced 
by  10  litres  of  wine.  The  temperature  should  be 
about  30°.  Oxygen  is  supplied  by  a  proper  system  of 


MICROBES,   OE  BACTERIA.  97 

ventilation.  This  process  is  somewhat  slow,  since  it 
only  produces  ten  litres  of  vinegar  out  of  each  tun  in 
the  course  of  the  week,  and  it  has  the  disadvantage 
of  encouraging  the  multiplication  of  anguillidce,  the 
small  nematoid  worms  which  live  in  vinegar  and  sour 
paste. 

Pasteur  has  modified  and  improved  the  original 
process  so  as  to  obviate  both  inconveniences.  He 
employs  heat,  which  allows  the  process  of  acetification 
to  be  intermittent,  and  thus  prevents  the  development 
of  the  anguillidce.  Shallow  vats,  about  30  centi- 
metres in  depth,  with  lids  in  which  holes  have  been 
pierced,  are  used,  and  mycoderma  is  scattered  on  their 
surface.  Gutta-percha  tubes,  pierced  with  holes  at 
their  lower  extremity,  are  placed  at  the  bottom  of 
these  vats,  so  that  fresh  liquid  can  be  added  without 
disturbing  the  superficial  film  of  mycoderma. 

In  Germany,  vinegar  is  made  by  means  of  spongy 
platinum,  or  platinum  black,  which  oxidizes  alcohol 
without  the  intervention  of  a  microbe.  This  affords 
a  good  example  of  fermentation,  or  of  an  analogous 
phenomenon,  produced  solely  by  physico-chemical 
action.  The  platinum  black  acts  by  disintegrating 
the  alcohol  and  placing  it  in  more  intimate  contact 
with  the  oxgyen  of  the  air,  since  the  process  of 
oxidation  would  be  much  slower  without  either  this 
process  or  the  presence  of  the  ferment. 


98  MICKOBES,  FEKMENTS,   AND  MOULDS. 

IV.  THE  MICROBES  WHICH  AFFECT  WINE. 

The  affections  to  which  some  wines  are  subject 
alter  their  taste  and  quality  so  as  often  to  render 
them  unfit  for  use.  These  affections  ought  to  be 
recognized,  so  that  a  diseased  wine  may  not  be  con- 
founded with  one  which  is  adulterated,  and  it  is  by 
means  of  the  microscope  that  we  are  enabled  to 
recognize  the  nature  of  these  changes.  Chaptal  for- 
merly ascribed  them  to  the  presence  of  an  excess  of 
ferment,  since  he  was  unable  to  discover  any  other 
cause.  We  now  know  from  Pasteur's  valuable  re- 
searches, published  in  his  book,  Etudes  sur  les  vins, 
that  they  are  all  due  to  the  presence  of  microbes 
peculiar  to  each  disease. 

"  The  source  of  the  diseases  which  affect  wine," 
Pasteur  writes,  "  consists  in  the  presence  of  parasitic 
microscopic  plants,  which  are  found  in  wine  under 
conditions  favourable  to  its  development,  and  which 
change  its  nature  either  by  the  withdrawal  of  what 
they  take  for  their  own  nutriment,  or  still  more  by 
the  formation  of  fresh  products  which  are  due  to  the 
multiplication  of  these  parasites  in  the  wine."  These 
diseases  are  known  under  the  names  of  acescence, 
pousse,  graisse,  amertume,  etc.  We  shall  review  them 
in  succession. 

Mouldy  or  Flowered  Wine. — These  are  wines  on  the 
surface  of  which  white  pellicles  are  formed  (fleurs  de 
viri),  which  consist  of  Mycoderma  vini  (Figs.  43,  53). 


MICROBES,   OR  BACTERIA. 


99 


This  product  does  not  turn  the  wine  sour,  nor  sensibly 
affect  it.  It  is  due  to  the  temperature  of  the  casks 
being  too  high  during  the  hot  season.  It  may  be 
obviated  by  sprinkling  them  with  cold  water,  or  by 
putting  ice  into  them ;  care  must  also  be  taken  to 
keep  the  casks  full,  and  the  cellars  as  cool  as  possible. 
Acidity  of  Wines ;  Soured  Wines.— Wine  always 


Fig.  53.— The  disease  acescence,  which  sours  wine.  Deposit  seen  in  the  microscope; 
1, 1,  Mycoderma  vini;  2,  2,  Mycoderma  aceti,  still  young ;  3,  the  same  older,  when 
the  mischief  is  at  an  advanced  stage. 

contaios  a  small  quantity  of  acetic  acid,  and  when 
this  acid  is  in  excess,  the  wine  is  no  longer  drinkable, 
and  turns  to  vinegar.  This  change  is  due  to  the 
presence  of  Mycoderma  aceti  (Fig.  53),  of  which  we 
have  already  spoken.  It  is  much  more  minute  than 
M.  vini,  and  takes  the  form  of  the  figure  8,  as  the 
illustration  shows,  or  of  chaplets  formed  by  the  union 


100          MICROBES,  FERMENTS,  AND  MOULDS. 

of  several  8's  placed  end  to  end.  As  they  grow  older, 
the  two  globules  of  the  8  divide,  and  appear  as  isolated 
granules.  These  two  species  of  Mycoderma  are  in- 
compatible, and  are  never  found  in  the  same  wine. 

The  acid  may  be  isolated  by  distilling  the  sour 
wine.  The  attempt  has  been  made  to  cure  or  im- 
prove sour  wine  by  adding  normal  potassium  tartrate 
(from  200  to  400  grammes  to  every  hogshead  of  230 
litres),  which  forms  potassium  acetate  and  bi tartrate 
by  neutralizing  the  excess  of  acid.  The  bitartrate  is 
deposited  spontaneously,  and  crystallizes.  Carbonate 
of  lime  cannot  be  employed  for  the  same  purpose, 
since  it  would  spoil  the  wine. 

Wines  that  are  turned  or  over-fermented  (vins 
pousses  ;  vins  bleus"). — This  disease  displays  the  follow- 
ing characters :  the  wine  assumes  a  bluish  or  brown 
colour,  and  becomes  turbid;  if  shaken  in  a  test-tube, 
we  may  observe  silky  waves  floating  in  every 
direction.  When  a  cask  is  tapped,  the  wine  spurts 
up,  and  it  is  said  "  qu'il  a  la  pousse."  If  poured 
into  a  glass,  a  number  of  minute  bubbles  appear  on 
the  surface,  the  discolouration  increases,  and  the  wine 
becomes  more  turbid.  The  taste  is  changed  and 
becomes  insipid,  as  if  water  had  been  added.  The 
disease  is  developed  in  very  hot  weather  (Chevalier 
and  Baudrimont). 

This  affection  is  due  to  the  presence  of  an  ex- 
tremely attenuated  microbe,  somewhat  resembling 
that  of  lactic  acid,  which  we  shall  describe  presently, 


MICROBES,  OR  BACTERIA.  101 

but  differing  from  the  latter  in  its  undivided  filaments. 
Its  diameter  is  at  the  most  one  micro-millimetre :  it 
varies  in  length,  and  is  flexible,  in  which  it  resembles 
the  genus  Vibrio.  These  filaments  collect  in  a 
mucous  deposit  at  the  bottom  of  the  cask  (Fig.  54). 

Wine  undergoes  successive  changes  under  the  in- 
fluence of  this  pathogenic  ferment,  and  this  has  led 


Fig.  54. — Wines  affected  by  pousse.  Deposit  seen  undor  the  microscope  :  1,  ordinary 
alcoholic  wine-ferment ;  2,  acicular  crystals  of  potassium  bitartrate ;  3,  crystals 
of  normal  calcium  tartrate ;  4,  Vibrio,  or  microbe  which  produces  the  disease. 

to  the  belief  that  there  are  several  distinct  diseases ; 
hence  the  different  names  which  have  been  given  to 
this  affection. 

The  remedies  for  the  disease  consist  in  the  ad- 
dition of  tartaric  acid ;  in  drawing  off"  the  wine  into 
sulphured  casks,  and  adding  a  little  brandy ;  and  in 
taking  care  to  keep  the  cellars  whitewashed  and  airy. 


102          MICROBES,  FERMENTS,   AND  MOULDS. 

Wine  affected  "by  Bopiness. — White  wines,  and 
especially  champagne,  are  more  often  affected  by  this 
disease  than  red  wines.  It  is  more  apt  to  attack  wine 
which  has  little  alcohol  and  is  deficient  in  tannin, 
and  under  its  influence  the  liquor  becomes  turbid,  flat, 
and  insipid,  ropy,  like  white  of  egg,  and  it  loses  its 
sugar. 

This  change  is  effected  by  a  filamentous  microbe, 


Fig.  55.— Disease  of  ropiness  in  wine,  affecting  champagne,  and  caused  by  a  bacterium 
which  assumes  two  forms  :  the  figure  8,  and  chaplets. 

even  more  like  the  lactic  ferment  (Fig.  58)  than  the 
one  we  have  just  described,  since  it  is  likewise  formed 
of  very  minute  globules,  united  in  chaplets,  which 
are,  however,  more  attenuated  than  those  of  the  lactic 
ferment.  These  filaments  form  a  species  of  feltwork 
through  which  the  liquid  slowly  filters;  hence  its 
oily  appearance.  It  is  probably  a  bacterium  (Fig.  55). 


MICROBES,  OB  BACTERIA.  103 

This  ferment  may  be  destroyed  by  tannin  (15 
grammes  to  a  hogshead),  which  has  the  effect  of  pre- 
cipitating it.  Very  ripe  sorbs,  which  have  been  crushed, 
may  also  be  used  for  this  purpose,  as  well  as  gall- 
nuts  and  grape-seeds  which  have  been  ground  to 
powder ;  all  substances  rich  in  tannin.  The  precipitate 
thus  formed  should  be  separated  from  the  wine  by 
refining. 

Wines  affected  by  Bitterness. — This  disease  affects 
red  wines,  especially  those  of  the  choicest  vintages 
of  Burgundy.  Pasteur  writes  that  "at  its  outset 
the  wine  assumes  a  peculiar  smell,  its  colour  is  less 
vivid,  and  its  taste  becomes  insipid.  Soon  the  wine 
becomes  bitter,  and  there  is  a  slight  taste  of  fermen- 
tation, due  to  the  presence  of  carbonic  acid  gas. 
Finally,  the  disease  becomes  more  aggravated,  the 
colouring  matter  is  completely  changed,  and  the  wine 
is  no  longer  drinkable." 

The  microbe  which  is  the  essential  cause  of  this 
disease  is  seen  under  the  micrpscope  in  the  form  of 
articulated  filaments,  curled  back  or  bent,  and  it  may, 
or  may  not,  be  invested  with  the  colouring  matter  of 
the  wine.  It  is  reproduced  by  fission,  not  by  bud- 
ding. It  is  probably  a  bacillus  (Fig.  56). 

This  ferment  must  not  be  confounded  with  that 
of  wine  affected  by  pousse,  of  which  the  filaments  are 
much  more  slender,  the  articulations  are  hardly  apparent, 
and  they  are  not  incrusted  with  colouring  matter. 
Pousse  is  readily  developed  in  wines  of  inferior  quality, 


104          MICEOBES,   FEKMENTS,   AND  MOULDS. 

while   the   finer   sorts  are  more   often  attacked   by 
bitterness. 

The  bitterness  may  be  to  some  extent  neutralized 
by  the  addition  of  new  and  sweet  wines,  but  the 
application  of  lime  (from  25  to  50  centigrammes  the 


Fig.  56. — Bitter  disease  of  wine.  Deposit  under  the  microscope :  1, 2,  filaments  of  the 
microbe  (Bacillus'}  which  produces  the  disease,  mixed  with  crystals  of  tartar  and 
colouring  matter  (Bordeaux  wine)  ;  3,  young  microbes  in  an  active  state ;  4,  dead 
microbes,  incrusted  with  colouring  matter. 

litre)  is  more  recommended.  This  treatment  mast, 
however,  make  the  wine  sour. 

The  deposits  formed  in  deteriorating  or  old  wines 
are  not  effected  by  the  microbes  which  we  have  just 
enumerated,  but  are  due,  according  to  Pasteur,  to 
the  combination  of  oxygen  with  the  wine  under  the 
action  of  time.  This  constitutes  the  aging  of  wine. 

Viscous  Fermentation  of  Saccharine  Liquids. — 
What  is  termed  viscous  fermentation  takes  place  in  the 


MICROBES,  OR  BACTERIA.  105 

juice  of  beetroots,  carrots,  and  onions,  and  in  liquids 
containing  sugar  and  nitrogenous  substances.  It  is 
probably  produced  by  the  same  ferment  which  causes 
the  ropiness  of  wine  (Fig.  55),  and  the  liquid  assumes 
a  viscous  or  oily  appearance. 

Pasteur  states  that  this  microbe  acts  on  the  glucose 
and  transforms  it  into  gum  or  dextrine,  into  mannite 
and  carbonic  acid.  The  lactic  and  butyric  fermenta- 
tions, which  are  often  simultaneously  produced  in 
saccharine  liquids,  are  due  to  distinct  microbes. 


V.  THE  MICROBE  OF  LACTIC  FERMENTATION. 

The  sugar  contained  in  milk,  as  well  as  grape 
sugar,  can  be  transformed  into  lactic  acid.  This 
transformation  is  always  caused  by  the  presence  of 
a  ferment  with  which  Pasteur  has  made  us  ac- 
quainted. It  had  been  previously  supposed  that  milk 
turned  sour  spontaneously  when  it  was  allowed  to 
stand  for  some  days.  In  this  case,  as  we  know,  the 
milk  curdles,  and  the  clear  liquid  which  separates 
from  the  curd  is  called  whey.  In  1780,  Scheele,  the 
celebrated  Swedish  chemist,  extracted  lactic  acid  from 
whey.  The  same  acid  is  also  found  in  sour-crout; 
in  the  sour  water  of  starch ;  in  baker's  yeast ;  in  water 
in  which  peas,  beans,  or  rice  have  been  boiled,  and  then 
suffered  to  ferment ;  and,  finally,  in  the  juice  of  beet- 
root which  has  passed  through  viscous  and  alcoholic 


106          MICROBES,   FERMENTS,  AND  MOULDS. 

fermentation,  after  which  it  turns  sour  and  produces 
lactic  acid  and  mannite. 

Lactic  fermentation  requires  the  presence  of  pro- 
teid  matters  in  process  of  decomposition,  and  it  can 
only  oe  carried  on  when  the  degree  of  acidity  in  the 
liquid  does  not  exceed  definite  limits.  For  this  purpose 
a  certain  amount  of  chalk  is  added,  to  neutralize  the 
acid  formed  at  the  expense  of  the  sugar. 

It  is  somewhat  difficult  to  observe  the  microbe  of 
this  fermentation  without  previous  instruction.  It 
appears  in  the  form  of  grey  patches,  which  are  readily 
confounded  with  casein,  and  with  the  disintegrated 
gluten,  or  the  chalk  of  the  liquid  under  examination. 


Fig.  57.— Lactic  ferment  in  a  Fig.  58. — Lactic  ferment 

chaplet  (Schutze.iberger).  (Pasteur). 

Under  the  microscope  the  patch  is  seen  to  consist  of 
minute  globules,  or  of  filaments  with  very  short  articu- 
lations, isolated  or  in  flakes.  These  are  the  characters 
of  the  genus  Bacterium  (Figs.  57,  58).  The  globules 
are  much  more  minute  than  those  of  the  yeast  of  beer, 
and  are  strongly  agitated  when  in  isolation  by  a 
motion  incorrectly  termed  Brownian  movement,  and 
which  does  not  in  reality  differ  from  the  movements 
which  may  be  observed  in  most  of  the  spores  of  the 
lower  orders  of  plants,  and  in  a  great  number  of 
bacteria. 


MICROBES,  OR  BACTERIA.  107 

This  ferment  is  often  found  in  wine,  together  with 
those  of  yeast  and  alcohol,  and  produces  in  it  an  in- 
cipient lactic  fermentation.  The  predominance  of  one 
of  these  fermentations  depends  on  the  composition 
of  the  medium,  which  may  be  more  or  less  adapted 
to  them.  A  slightly  alkaline  medium  is  most  suitable 
for  the  lactic  microbe,  while  in  a  perfectly  neutral 
medium  only  alcoholic  fermentation  will  occur. 

We  have  already  said  that  mare's  milk  can  be 
transformed  into  an  alcoholic  liquid  called  koumiss. 


VI.  THE  AMMONIACAL  FERMENTATION  OF  URINE. 

Shortly  after  its  discharge,  urine  which  is  left  to 
itself  assumes  an  aimnoniacal  odour.  This  is  due 
to  the  transformation  of  the  urea  (the  nitrogenous 
principle  of  urine)  into  ammonia  and  carbonic  acid, 
under  the  influence  of  a  microbe  which  appears  in 
the  form  of  free  globules,  of  articulated  filaments 
(Torula),  or  of  chaplets,  resembling  those  of  the  lactic 
ferment.  This  microbe  is  found  in  the  white  deposit 
which  collects  at  the  bottom  of  vessels,  and  has  been 
termed  Micrococcus  uress  (Fig.  59). 

This  ferment  is  conveyed  through  the  air,  like 
other  microbes  of  fermentation.  It  does  not  exist  in 
the  bladder  as  long  as  the  urine  remains  acid.  Yet, 
in  the  rare  cases  in  which  urine  has  been  found  to  be 
alkaline,  immediately  after  its  issue  from  the  bladder, 


108          MICROBES,  FERMENTS,  AND  MOULDS. 

it  may  be  ascertained  that  the  ferment  was  introduced 
by  some  accidental  cause,  such  as  a  surgical  examina- 
tion, and  that  the  sound  served  to  convey  the  microbe. 
It  is,  in  any  case,  sufficiently  common  at  the  exterior 
orifice  of  the  urethra,  and  at  the  depth  of  two  or  three 
centimetres. 

Von  Tieghem  has  shown  by  precise  experiments 


Fig.  59. — Micrococcus  urea  (Von  Tieghem).  Microbe  of  amraoniacal  fermentation. 
It  may  be  observed  that  the  bacterium  is  in  the  figure  8,  or  in  chaplets.  (Much 
magnified.) 

that  the  presence  of  this  microbe  is  the  true  cause  of 
the  ammoniacal  fermentation  of  urine.  With  certain 
precautions,  the  urine  withdrawn  from  a  healthy 
bladder  may  be  preserved  for  an  indefinite  time. 

These  experiments  have  been  recently  resumed  by 
Sternberg,  an  American  physician,  who  has  clearly 
demonstrated  that  only  the  microbes  of  the  air,  or 


MICROBES,  OR  BACTERIA.  109 

those  of  the  orifice  of  the  urethra,  can  produce  this 
fermentation.  Since  the  latter  are  always  carried  off 
by  the  first  discharge  of  urine,  only  the  second  por- 
tions of  the  emitted  liquid  should  be  collected  in 
a  perfectly  clear  vessel,  which  has  been  sterilized, 
or,  carefully  freed  from  all  atmospheric  germs.  The 
vessel  should  then  be  put  under  a  glass  shade  to 
protect  it  from  these  germs,  and  if  all  proper  pre- 
cautions are  taken,  the  urine  will  remain  clear  and 
acid  for  an  indefinite  time  without  undergoing  am- 
moniacal  fermentation.  If  afterwards  a  little  plug 
of  amianthus,  which  has  been  previously  sterilized 
by  heat,  should  be  introduced  by  a  small  pair  of 
pincers  into  the  urethra  to  a  depth  of  two  centi- 
metres, and  then  dropped  into  this  untransformed 
urine,  it  will  soon  be  transformed,  and  undergo  am- 
moniacal  fermentation.  But  if  the  plug  of  amianthus 
has  been  steeped  in  an  antiseptic  solution  (diluted 
carbolic  acid)  before  being  introduced  into  the  urethra, 
it  will  not  produce  this  fermentation. 

VII.  BUTYRIC  FERMENTATION  OF  BUTTER,  CHEESE, 
AND  MILK. 

Butyric  fermentation  follows  lactic  fermentation  in 
milk,  butter,  and  cheese,  and  it  is  butyric  acid  which 
gives  to  butter  its  rancid  taste.  This  fermentation 
also  occurs  in  saccharine  substances,  and  generally 
in  all  proteid  substances. 


110          MICROBES,  FERMENTS,   AND  MOULDS. 

Pasteur  has  ascertained  that  this  fermentation 
results  from  the  development  of  a  microbe  which 
takes  the  form  of  minute  cylindrical  rods,  rounded  at 
their  extremities,  usually  straight,  and  either  isolated 
or  united  in  chains  of  two  or  more  articulations. 
These  rods  are  about  two  micro-millimetres  in  width, 
and  from  two  to  twenty  micro-millimetres  in  length. 
They  advance  with  a  gliding  motion,  are  often  curved, 
and  present  slight  undulations.  They  are  reproduced 
by  fission.  These  characters  are  those  of  the  genus 
bacillus. 

Coagulation  of  Milk:  Cheese. — The  coagulation  of 
milk  is  artificially  produced  by  rennet,  the  liquid 
secreted  in  a  calf's  stomach.  Human  gastric  juice 
produces  the  same  effect,  and  the  milk  introduced  as 
an  aliment  into  the  stomach  is  never  digested  until  it 
has  been  curdled,  both  in  children  and  adults.  The 
artichoke  flower,  and  other  plants  of  the  genus  Car- 
duus,  will  also  curdle  milk  at  a  temperature  between 
30°  and  50°.  It  is  probable  that  this 
action  is  due  to  the  presence  of  an 
organized  ferment  (animal  or  vege- 
.  BO.- saeaiiu  amy-  table  cells),  which  here  supplies  the 
cM«)fbutyric  ferment  place  of  the  microbe  of  lactic  f  ermen- 

agent  in  the  fabrica- 
tion of  cheese,  tation. 

It  is  with  rennet,  or  with  the  still  more  active 
liquid  produced  by  the  maceration  of  the  testicle  of  an 
unweaned  calf,  that  those  cheeses  are  made  which 
consist  only  of  curd,  boiled  or  unboiled,  fresh  or  fer- 


MICROBES,  OR  BACTERIA.  Ill 

mented,  and  obtained  from  the  milk  of  cows,  sheep, 
or  goats,  skimmed  or  unskimmed,  according  to  the 
kind  of  cheese  desired. 

Sweet-milk  cheese  do  not  differ  in  their  composi- 
tion from  those  of  curdled  milk.  They  consist  of  casein, 
albuminoid  matter  which  encloses  particles  of  butter : 
the  liquid  residue  is  the  serum  or  whey,  which  con- 
tains lactic  acid  and  mineral  salts. 

Cheese,  strictly  so  called,  such  as  Gruyere  and 
Roquefort,  only  differ  from  the  foregoing  because  they 
have  been  exposed  for  a  shorter  or  longer  time  to  the 
action  of  the  air,  and  of  the  microbes  suspended  in  it. 
Cheese  is  first  oxidized  under  the  influence  of  the 
oxygen  of  the  air ;  butyric  and  even  alcoholic  fermen- 
tation soon  follows  lactic  fermentation,  together  with 
the  disengagement  of  hydrogen  and  of  putrid  pro- 
ducts, when  the  action  of  the  ferments  which  effect 
these  transformations  has  gone  on  too  long. 

In  order  to  obtain  the  different  kinds  of  cheese 
which  come  into  the  market,  they  are  exposed  to  the 
weather,  generally  in  holes  which  have  been  excavated 
in  the  rock  for  this  purpose,  on  a  bed  of  straw,  or 
sometimes  partially  covered  with  it,  until  the  cheese 
is  ripe  and  has  attained  the  desired  quality. 

Butyric  and  ammoniacal  fermentations  lead  us 
directly  to  the  study  of  putrefaction ;  that  is,  the  fer- 
mentation of  dead  organic  matter. 


112          MICEOBES,   FERMENTS,  AND  MOULDS. 


VIII.    PUTREFACTION,    OR    THE    FERMENTATION    OF 
DEAD  ORGANIC  MATTER;  A  GAME  FLAVOUR. 

The  flesh  of  animals  used  for  food  is  said  to  be 
high  in  the  first  stage  of  alteration  which  occurs  when 
it  is  left  to  itself.  Pasteur  does  not  believe  that  this 
effect  is  produced  by  the  intervention  of  the  ferments 
of  the  air,  although  this  is  the  case  with  the  putrefac- 
tion which  follows.  He  thinks  that  it  merely  results 
from  the  action  of  what  are  called  soluble  or  natural 
ferments  in  the  serum  of  the  meat,  and  that  there  is 
a  chemical,  reciprocal  reaction  of  the  liquids  and  solids 
which  are  withdrawn  from  the  normal  action  of  vital 
nutrition.  This  explanation  is  adapted  to  satisfy  those 
epicures  who  have  a  taste  for  high  game  and  not  for 
microbes.  Yet  it  is  certain  that  this  condition  passes 
into  true  putrefaction  without  any  abrupt  transition, 
and  we  know  that  immediately  after  death  the  microbes, 
which  penetrate  everywhere,  take  possession  of  the 
animal  tissues  and  begin  their  work  of  destruction. 
When  flesh  is  high,  it  is  therefore  probable  that  it 
is  in  the  first  stage  of  putrefaction. 

Gautier  has  made  some  experiments  on  the  sub- 
ject, and  holds  that  this  condition  is  certainly  due 
to  the  action  of  microbes,  and  consequently  to  germs 
in  the  air.  In  fact,  meat  which  is  placed  in  a  soldered 
and  air-tight  case  after  it  has  been  deprived  of  germs 
by  a  suitable  process,  is  devoid  of  any  high  odour  at 


MICROBES,  OR  BACTERIA.  113 

the  end  of  six  months,  and  is  as  fit  for  food  as  freshly 
killed  meat. 

However  this  may  be,  meat  which  is  high  is 
usually  not  injurious,  while  putrefied  meat  produces 
diarrhoea  or  still  more  serious  illness.  Davaine  has 
shown  that  the  septic  properties  of  decomposed  blood 
are  not  removed  by  subjecting  it  to  a  temperature 
of  100°,  which  destroys  the  microbes,  but  not  their 
germs  or  spores;  for  the  destruction  of  the  latter  a 
still  higher  temperature  is  necessary. 

For  a  long  while  it  was  believed  that  the  putrefac- 
tion of  dead  bodies,  and  of  albuminoid  substances, 
either  animal  or  vegetable,  which  have  been  exposed 
to  a  moist  air  at  a  temperature  of  from  15°  to  30°,  was 
merely  due  to  the  instability  of  the  organic  compounds; 
these,  when  left  to  themselves,  tend,  under  the  influence 
of  oxygen,  to  produce  more  stable  compounds  by  dis- 
integration and  successive  oxidations.  Pasteur  has, 
however,  shown  that  in  this  case  also  there  is  a  true 
fermentation;  that  is,  a  decomposition  produced  by 
the  vital  action  of  certain  microbes. 

In  general,  when  organic  animal  substances  are 
exposed  to  the  air,  they  are  in  the  first  instance 
rapidly  covered  with  moulds;  they  lose  their  co- 
herence, and  after  the  lapse  of  a  few  days  give  off 
fetid  effluvia.  Carbonic  acid,  nitrogen,  hydrogen, 
carburetted,  sulphuretted,  and  phosphoretted  hydro- 
gens, are  freely  disengaged,  and  at  the  same  time  they 
combine  with  the  oxygen  of  the  air.  The  microbes, 


114          MICROBES,  FERMENTS,  AND  MOULDS. 

which  appear  simultaneously  with  the  moulds,  pene- 
trate deeply  into  the  tissues,  disintegrate  them  by 
feeding  at  their  expense,  and  the  putrid  condition 
increases ;  then  the  decomposition  changes  its  nature 
and  becomes  less  intense.  The  putrefied  matter  is 
finally  desiccated,  and  leaves  a  brown  mass— a  complex 
mixture  of  substances  combined  with  water  (hydro- 
carbons), and  of  fatty  and  mineral  substances  which 
gradually  disappear  by  slow  oxidation  (Gautier). 

Pasteur    has    ascertained,    from    the    microscopic 


^8V,)_ 

"I 


<?       l*» 


Fig.  61.— Bacilli  of  pu- 
trefaction (Rosenbach: 
much  magnified)  Fig.  62. — Zoogloea  of  Spirillum  tenue. 


study  of  the  phenomena  which  occur  in  an  infusion 
of  animal  matter  in  process  of  decomposition,  that 
microbes  appear  in  it  in  the  form  of  globules  or 
short  rods  (Micrococcus,  Bacterium  termo,  Bacillus, 
etc.),  which  are  either  free  or  collected  in  a  semi- 
mucilaginous  mass,  to  which  the  special  name  zoogloea 
was  at  first  given  (Fig.  62).  These  microbes  rapidly 
deprive  the  liquid  of  all  its  oxygen.  At  the  same 
time  a  thin  layer  of  mucedinece  and  of  bacteria  is 


MICROBES,   OR  BACTERIA.  115 

found  on  the  surface,  which  also  absorb  this  gas  and 
do  not  allow  it  to  penetrate  into  the  lower  part  of 
the  liquid. 

This  liquid  now  becomes  the  seat  of  two  very 
distinct  actions.  In  its  interior,  vibriones  succeed  to 
the  free  globules  and  zoogloea,  of  which  they  appear 
to  be  only  a  higher  stage  of  transformation.  These 
microbes  multiply  and  change  the  albuminoid  matter 
into  more  simple  substances ;  insoluble  cellulose,  fatty 
bodies,  and  gaseous  putrid  matters.  Meanwhile,  the 
microbes  on  the  surface  actively  consume  the  products 
thus  developed,  transforming  them  into  carbonic  acid, 
nitrogen,  and  the  oxides  of  nitrogen,  etc.  This  ex- 
plains why,  when  there  is  an  insufficiency  of  oxygen? 
putrefaction  may  indeed  begin ;  but  it  languishes,  and 
is  finally  arrested. 

The  cause  of  the  fetid  odours  which  escape  from 
putrefying  bodies  and  liquids  is  not  well  understood. 
It  may  be  ascribed  to  the  disengaged  gases  (carburetted, 
phosphoretted  and  sulphuretted  hydrogen,  and  ammo- 
niacal  compounds),  and  to  the  circulation  of  decom- 
posing organic  particles.  We  also  find  formic,  acetic, 
lactic,  butyric,  valerianic,  and  capro'ic  acids,  generally 
combined  with  ammonia,  and  the  fatty  acids  which 
are  one  result  of  the  successive  disintegrations  of 
albuminoid  matters. 

When  these  gases  are  disengaged,  a  substance 
remains  which  may  be  compared  with  humus,  or 
vegetable  earth.  It  is  rich  in  fats,  in  earthy  and 


116          MICROBES,  FERMENTS,   AND  MOULDS. 

ammoniacal  salts,  and  consequently  constitutes  a 
strong  manure,  very  fit  to  serve  as  the  nutriment  of 
plants. 

This  is  at  once  the  beginning  and  the  termination 
of  the  endless  chain  which  sustains  the  equilibrium 
of  nature,  in  which  there  is  no  creation,  no  destruction. 
Plants  draw  their  nutriment  from  the  soil  and  the  air 
in  the  form  of  mineral  solutions,  and  are  devoured 
by  animals  or  by  other  parasites ;  animals  are  in  their 
turn  devoured  by  microscopic  plants  or  microbes,  and 
return  by  means  of  putrefaction  to  the  condition  of 
mineral  salts,  which  are  distributed  in  the  soil,  and 
serve  anew  for  the  nutrition  of  plants. 

We  must  at  the  same  time  be  struck  by  the 
resemblance  which  exists  between  these  phenomena 
of  putrid  fermentation,  and  those  which  occur  in  the 
fermentations  which  accompany  the  nutrition  of 
animals  and  plants.  Germination  and  the  different 
digestions  which  occur  in  the  mouth,  the  stomach, 
the  intestines,  etc.,  are  only  fermentations,  so  that 
Mitscherlich  has  paraphrased  the  Scripture  saying, 
"Dust  thou  art,  and  unto  dust  thou  shalt  return," 
by  declaring  that  "  Life  is  only  a  corruption." 

It  should,  however,  be  remembered  that  fermenta- 
tions are  essentially  phenomena  of  disintegration, 
which  always  reduce  complex,  organic  substances  to 
those  which  are  simpler.  Plants  provided  with 
chlorophyl,  on  the  other  hand,  alone  possess  the 
property  of  forming  higher  organic  compounds,  by 


MICROBES,  OB  BACTERIA.  117 

the  aid  of  purely  inorganic  substances.  Animals  and 
plants  devoid  of  chlorophyl  get  their  nutriment  by 
unmaking  the  complex  substances  elaborated  by  the 
green  parts  of  plants,  and  these  act  in  the  same  way 
for  their  own  profit  in  those  organs  which  have  no 
chlorophyl ;  as,  for  instance,  in  the  seed  and  embryo. 


IX. — AEROBIES  AND  ANAEROBIES. 

We  have  seen  that  microbes,  at  different  epochs 
of  their  existence,  and  in  accordance  with  the  nature 
of  their  environment,  can  assume  very  diverse  forms. 
Thus  the  organism,  which  at  first  appears  in  the  form 
of  globules  (micrococcus),  either  isolated  or  united  in 
more  or  less  numerous  colonies  by  a  kind  of  muci- 
laginous envelope  (Zoogloea),  when  it  again  becomes 
free,  may  be  elongated  in  the  shape  of  the  figure  8, 
which  is  formed  of  two  cells  about  to  separate;  or 
a  large  number  may  be  included  in  the  form  of  a 
straight,  articulated  rod  (Bacterium),  or  in  a  rod 
which  is  curved,  waved,  or  even  spiral  (Vibrio, 
Spirillum,  Spirochcete),  always  more  or  less  mobile; 
or,  again,  the  cells  may  form  long,  stationary  filaments 
(Bacillus),  etc. 

So  also  the  habitat  and  mode  of  life  divide  the 
microbes  into  very  distinct  classes.  Some  can  only 
ibsist  when  they  breathe  the  natural  oxygen  they 
ithdraw  from  the  atmosphere;  they  can  only  exist 


118 


MICROBES,   FERMENTS,  AND  MOULDS. 


on  the  surface  of  liquids,  or  of  the  organic  substances 
on  which  they  feed.  These  are  termed  aerobies,, 
or  consumers  of  air.  Others,  again,  can  live  beneath 
the  surface  of  liquids  and  in  living  organisms,  or  of 
those  in  process  of  decomposition,  and  must  neces- 
sarily derive  the  oxygen  necessary  for  their  respira- 
tion from  the  oxygenated  substances  in  which  they 
are  found.  These  are  termed  anaerobies. 


a  m  p  n 

Fig.  63. — Vibrio  rugula  in  different  stages  of  development  (anaerobic),  much  enlarged. 

This  distinction  and  the  theory  on  which  it  relies 
have  been  introduced  into  science  by  Pasteur,  and 
they  appear  to  be  founded  on  observed  facts.  Thus 
Bacterium  termo,  which  lives  on  the  surface  of  putre- 
fying liquids,  is  an  aerobie ;  while  Vibrio  rugula 
(Fig.  63),  which  lives  below  the  surface  of  the  liquid, 
below  the  layer  formed  by  the  Bacterium  termo,  is  an 
anaerobic,  and  derives  its  oxygen  from  the  water  or 
solid  matters  which  are  found  in  it  in  suspension  or 
solution,  and  even  from  other  microbes.  So,  again, 
the  yeast  of  superior  beer  is  an  aerobie,  and  the  yeast 
of  inferior  beer  is  an  anaerobic,  etc.  Paul  Bert  regards 


MICROBES,   OR  BACTERIA.  119 

the  corpuscles  of  the  blood,  and  the  cells  of  which  all 
our  tissues  consist,  as  true  anaerobic  microbes;  so 
likewise  are  the  microbes  which,  when  introduced  into 
the  blood,  are  the  cause  of  certain  diseases.  The 
important  consequences  of  this  fact,  which  it  is  neces- 
sary to  note,  will  appear  presently. 


X. — THE  MICROBES  OF  SULPHUROUS  WATERS. 

The  formation  of  the  sulphurous  springs  which 
are  so  numerous  in  the  Pyrenees  and  in  other  parts 
of  France,  appears  to  be  due  to  the  presence  of  small 

algae  of  the  family  Oscil-  

latoria,  and  of  the  genera 
Oscillaria  and  Beggiatoa, 
(Fig.  64).  These  microbes 

are  of  the  same  structure        Fig  ^_Beggiatoa  albai  microbe  of 
as  those  of  which  we  have  8ulphmous  8pring8- 

spoken  above,  but  they  contain  chlorophyl,  and  also 
a  blue  colouring  matter.  They  are  placed  in  the 
group  Cyanophycece,  which,  as  Zopf  believes,  contains 
species  that  are  sometimes  green,  and  sometimes 
colourless,  like  Bacillus  and  Leptothrix,  which  they 
resemble  in  their  mode  of  reproduction. 

According  to  Louis  Ollivier,  these  algae  reduce  the 
sulphates  of  waters  charged  with  sulphate  of  lime, 
uisforming  them  into  sulphur.     They  even  accumu- 
ite  sulphur  in   their  cells.     When   sulphur  is  thus 


120          MICROBES,   FERMENTS,  AND  MOULDS. 

abundantly  supplied  to  them,  the  microbes  are  very 
mobile ;  as  soon  as  the  quantity  of  sulphur  diminishes 
they  become  less  mobile,  and  reconsume  the  sulphur 
they  have  stored  up;  finally,  they  become  quite 
motionless — a  phenomenon  concomitant  with  the  forma- 
tion of  spores.  Within  each  cell  of  the  filamentous 
alga  there  is  a  minute  sphere,  brilliant  and  refracting, 
of  which  the  development  is  in  inverse  ratio  to  the 
quantity  of  sulphur  in  the  surrounding  liquid,  These 
spores  become  free  in  the  form  of  chaplets,  after  the 
destruction  of  the  cell-wall,  and  these  chaplets  are 
precisely  like  those  of  Bacillus  subtilis. 

Planchud  was  the  first  to  whom  it  occurred  to 
look  for  a  special  ferment  in  the  glairine  or  baregine 
which  may  be  seen  floating  on  the  surface  of  sul- 
phurous waters.  He  showed  that  one  gramme  of  car- 
bolic acid  to  a  litre  of  water  arrests  the  reduction  of 
the  sulphates  into  sulphur,  and  that  this  reduction  is 
resumed  as  soon  as  the  carbolic  acid  has  evaporated. 
Six  grammes  to  the  litre  completely  destroy  the 
Sulphwraria,  as  these  algae  are  termed  by  Planchud. 

This  observer  also  performed  experiments  which 
led  him  to  believe  that  the  same  algse  will  reduce 
gypsum  to  native  sulphur,  and  that  the  vast  deposits 
of  sulphur  found  in  certain  regions  are  due  to  the 
action  of  this  microscopic  plant.  It  is  now  well 
known  that  a  chemical  action  of  the  same  nature, 
the  production  of  saltpetre,  is  the  work  of  similar 
microbes. 


MICROBES,   OR  BACTERIA.  121 


XI.  THE  MICROBES  WHICH  PRODUCE  SALTPETRE. 

It  is  known  that  nitre  or  saltpetre,  i.e.  potas- 
sium nitrate,  is  produced  in  damp  places  where  de- 
composing animal  matter  is  found  in  contact  with 
carbonate  of  potassium.  It  is  found,  combined  with 
other  salts  of  lime,  soda  and  magnesia,  in  stables,  sheep- 
folds,  cellars,  in  the  neighbourhood  of  urinals,  and 
in  the  earth  of  some  localities  (Peru  and  Chili).  Its 
industrial  importance  in  the  manufacture  of  gun- 
powder, etc.,  has  led  to  its  collection.  Formerly  it 
was  extracted  from  the  plaster  of  old  houses,  or  from 
artificial  nitre  works  which  combined  conditions 
favourable  to  its  production.  Nitrates  are  produced 
by  the  gradual  oxidation  of  the  ammonia  furnished 
by  animal  excretions.  For  a  long  while  it  was  supposed 
that  this  oxidation  was  simply  due  to  the  influence 
of  porous  bodies,  such  as  earth  and  stone  walls.  Nitric 
acid  was  produced,  then  nitrates  of  lime,  potas- 
sium, etc. 

The  researches  of  Boussingault,  Schloesing,  and 
others,  have  now  taught  us  that  this  phenomenon  of 
organic  chemistry  is  due,  like  many  others,  to  the 
vital  activity  of  one  or  more  species  of  microbe, 
whose  invariable  presence  in  the  natural  or  artificial 
nitre-works  has  been  ascertained.  These  microbes  are 
aerobics,  i.e.  they  only  live  and  work  when  in  contact 
with  the  oxygen  of  the  air,  from  which  they  derive 


122          MICROBES,   FERMENTS,   AND  MOULDS. 

materials  for  effecting  oxidation.  This  is  another 
instance  of  the  part  played  by  microbes  in  artificial 
fermentation. 

Gayon  and  Dupetit  believe  that,  in  addition  to 
the  microbes  which  produce  nitre,  there  are  others 
which  decompose  the  nitrates  produced  by  the  former. 
When  nitrate  of  potassium  is  placed  in  culture- 
liquids,  drain-water,  chicken-broth,  etc.,  it  disappears 
rapidly  under  the  action  of  these  microbes.  Under 
favourable  conditions  of  temperature  and  environ- 
ment, culture  microbes  daily  reduce  one  gramme  of 
nitre  to  the  litre.  This  decomposition  causes  the  dis- 
engagement of  nitrogen,  the  formation  of  ammonia 
and  carbonic  acid,  which  latter  remain  in  solution  in 
the  form  of  bicarbonate.  Gayon  and  Dupetit  believe 
that  this  fact  explains  certain  chemical  phenomena 
which  occur  in  the  soil,  under  the  influence  of  manure 
and  water. 

Thus  fresh  discoveries  show  more  clearly  every 
day  the  importance  of  the  part  played  by  microbes 
in  nature.  Agriculture,  manufactures,  geology,  and 
chemistry  must  take  them  into  account,  since  they 
are  the  active  agents  of  a  number  of  phenomena 
which  have  hitherto  been  obscure  in  physics, 
chemistry,  and  physiology. 


MICROBES,   OB  BACTERIA.  123 


XII.    THE    MICROBES  WHICH   DESTROY  BUILDING 
MATERIALS. 

The  observations  of  Parize,  director  of  the 
agronomic  station,  Morlaix,  lead  to  the  belief  that 
microbes,  which  destroy  dead  bodies  and  effect  such 
various  transformations  in  nature,  not  only  attack 
the  beams  of  our  houses,  as  we  have  already  seen,  but 
building  materials  of  an  inorganic  nature,  including 
stones. 

On  one  occasion,  when  Parize  was  examining  some 
mucedinece  which  had  vegetated  on  a  brick  partition, 
in  a  closed  and  somewhat  damp  recess,  he  noticed 
blisters  on  the  coat  of  plaster.  He  broke  one  of  these 
blisters,  and  a  fine  red  dust,  consisting  of  pulverized 
brick,  issued  from  it.  When  placed  in  the  micro- 
scope, under  a  magnifying  power  of  about  300 
diameters,  he  saw,  amid  schistoid  fragments,  dia- 
tomatacese  and  silicious  algae  pertaining  to  the  original 
clay  of  the  bricks,  an  immense  number  of  living 
microbes  :  micrococcus,  bacteria,  amoebae,  and  ciliated 
spores  of  algae,  moving  rapidly  in  the  drop  of  water 
used  to  moisten  the  dust.  Some  of  these  were  in  process 
of  budding.  These  organisms  existed  under  a  coat 
of  five  to  six  mm.  of  plaster,  and  even  of  30  mm.  at 
the  bottom  of  a  hole  pierced  by  the  brace ;  but  in  this 
case  they  were  less  numerous,  in  the  proportion  of 
two  to  three.  The  germs  and  spores  which  exist 


124          MICROBES,  FERMENTS,  AND  MOULDS. 

both  in  air  and  water  may,  therefore,  be  indefinitely 
preserved  in  a  protective  medium,  such  as  a  brick 
wall  covered  with  plaster.  They  are  nourished  at 
the  expense  of  the  ammoniacal  salts  which  are  found 
in  the  air  in  a  gaseous  state,  and  which  are  fixed  by 
atmospheric  moisture,  and  it  is  probable  that  they 
derive  little  nutriment  from  the  solid  materials  in 
the  midst  of  which  they  live,  although  by  their 
increase  disintegration  may  ensue.  Hence,  especially 
from  the  hygienic  point  of  view,  it  is  so  important  to 
disinfect  the  walls  of  hospitals,  barracks,  stables,  etc., 
by  scraping  and  whitewashing  them. 

Parize  also  believes  that  microbes  may  perform 
a  geological  part  in  nature  by  disintegrating  the 
schistoid  rocks  which  enter  into  the  constitution  of 
arable  soil.  But  we  are  now  speaking  of  microbes  of 
recent  origin,  since  the  temperature  to  which  clay  is 
subjected  in  order  to  make  red  bricks  would  certainly 
destroy  all  the  microbes  and  their  germs.  This  is  not 
the  case  with  the  microbes  of  chalk,  which,  according 
to  Be'champ,  are  of  very  ancient  origin. 


XIII.  THE  MICROBES  OF  CHALK  AND  COAL. 

Be'champ's  researches  tend  to  show  that  microbes, 
which  he  calls  microzyma,  or  small  ferments,  have  an 
almost  indefinite  term  of  life.  We  know  that  chalk 
consists  almost  entirely  of  the  remains  of  the  calcareous 


MICROBES,  OB  BACTERIA.         125 

shell  of  Rkizopoddj  protozoaria  or  microscopic  animals 
which  lived  in  incalculable  numbers  in  the  seas  of  the 
secondary  period,  and  which  still  live  at  the  bottom 
of  oceans.  Be'champ  holds  that  the  organic  substance 
of  these  rhizopoda,  or  of  the  microbes  which  live  in 
their  midst,  has  retained  its  vitality  in  the  mass  of 
chalk,  since  a  freshly  cut  piece,  taken  from  the  quarry 
with  all  possible  precautions  to  exclude  air-germs,  is 
able  to  furnish  microbes  which  multiply  rapidly  in 
a  favourable  medium,  and  produce  various  fermenta- 
tions. We  have  already  seen  that  bacteria  germs 
resist  desiccation,  heat,  and  all  kinds  of  destructive 
influences,  and  remain  for  a  long  while,  even  for 
several  years,  in  the  condition  of  dormant  spores; 
but  the  existence  of  spores  of  the  same  kind  in  chalk 
of  the  secondary  period  indicates  a  still  more  sur- 
prising vitality.  It  is  not,  however,  inexplicable  if 
we  suppose  that  these  microbes  pass  through 
successive  periods  of  activity  and  repose,  and  if  we 
compare  these  facts  with  those  presented  by  the 
microbes  of  saltpetre,  of  mineral  waters,  and  of  the 
anaerobic  microbes,  which  are  able  to  live  when 
deprived  of  the  oxygen  of  the  air. 

Be'champ  was  the  first  to  observe  the  presence  of 
granulations  in  coal,  which  appear  under  the  micro- 
scope to  be  microbes.  These  microbes  must  be  far 
more  ancient  than  those  of  chalk,  but  they  have  lost 
all  vitality ;  it  has  been  found  impossible  to  develop 
them  in  infusions,  and  to  obtain  fermentations  from 


126          MICROBES,  FERMENTS,   AND  MOULDS. 

them.  But  this  cannot  always  have  been  the  case, 
and  it  has  been  supposed  that  the  phenomenon  of 
coal  formations,  still  so  obscure  and  so  variously 
explained,  was,  at  any  rate,  partially  due  to  the 
physiological  labour  of  these  microbes,  and  con- 
sequently belongs  to  the  class  of  fermentations. 


XIV.  CHROMOGENIC  MICROBES. 

In  addition  to  the  colourless  microbes,  such  as  are 
most  of  those  we  have  hitherto  considered,  there  are 
others  remarkable  for  their  vivid  and  varied  colours, 
which  betray  their  existence  to  the  least  practised 
eyes.  Many  of  these  microbes  attack  our  alimentary 
substances,  and  should  therefore  be  known  to  the 
manufacturer  and  hygienist,  since  their  action  on 
the  human  system  is  often  injurious. 

Many  phenomena  which  have  struck  the  imagina- 
tion of  ignorant  and  credulous  people  are  merely  due 
to  the  presence  of  these  coloured  microbes.  In  1819, 
a  peasant  of  Liguara,  near  Padua,  was  terrified  by 
the  sight  of  blood-stains  scattered  over  some  polenta, 
which  had  been  made  and  shut  up  in  a  cupboard  on 
the  -previous  evening.  Next  day  similar  patches 
appeared  on  the  bread,  meat,  and  other  articles  of 
food  in  the  same  cupboard.  It  was  naturally  regarded 
as  a  miracle  and  warning  from  heaven,  until  the  case 
had  been  submitted  to  a  Paduan  naturalist,  who  easilv 


MICROBES,   OR  BACTERIA.  127 

ascertained  the  presence  of  a  microscopic  plant,  which 
Ehremberg  likewise  found  at  Berlin  in  analogous  cir- 
cumstances, and  which  he  named  Monas  prodigiosa. 
At  that  time  all  microbes  were  confounded  in  the 
Monad  genus;  we  now  term  it  Micrococcus  pro- 
digiosus.  It  has  been  observed  not  only  on  bread, 
but  on  the  Host,  on  milk,  paste,  and  on  all  alimentary 
or  farinaceous  substances  exposed  to  damp  heat. 

This  microbe  has  been  recently  studied  by  Raben- 
horst,  who  declares  that  it  is  polymorphic,  and  has 
received  a  number  of  different  names :  Palmella  miri- 
fica,  Zoogalactina  imetropha,  Bacterium  prodigiosum, 
which  are  only  varieties  of  Micrococcus  prodigiosus, 
modified  by  the  medium  in  which  it  is  nourished. 
This  observer  noticed  its  appearance  on  cooked  meat 
kept  in  a  cellar.  The  spherical  cells,  examined  under 
the  microscope,  were  shown  to  be  filled  with  a  reddish 
oil,  which  gave  them  a  peach-blossom  tint,  and  when 
transferred  to  raw  meat  they  assumed  a  splendid 
fuchsia  colour,  resembling  spots  of  blood.  This  plant 
is  only  developed  in  the  dark,  and  the  nitrogen 
necessary  for  its  nutrition  must  be  derived  from  the 
air,  especially  when  it  is  developed  on  bread,  the 
Host,  etc.,  in  which  nitrogen  is  deficient. 

When  it  is  said  to  rain  blood,  this  phenomenon  is 
likewise  due  to  the  presence  of  a  minute  plant,  prob- 
ably similar  to  that  which  often  gives  a  red  tint  to 
ponds  and  reservoirs  in  autumn.  This  microscopic 
alga  appears  to  be  the  one  discovered  by  Ehremberg  in 


128          MICROBES,   FERMENTS,   AND  MOULDS. 


1836,  in  a  stream  near  Jena,  and  which  he  named  Ophi- 
domonas  jenensis,  or  sanguinea  (Fig.  65).  It  is,  on 
account  of  its  form,  now  placed  in  the  genus  Spirillum. 
Like  many  other  plants,  it  readily  passes  from  green 
to  red.  No  one  is  surprised  by  the  green  scum 
which  covers  reservoirs  in  summer,  since  it  is  so 
common;  but  when  this  colour  changes,  often  in  a 
single  night,  and  passes  from  green  to  red,  the  unaccus- 
tomed tint  excites  wonder,  although  it  is  caused  by 


Fig.  65. — Ophidomonas  sanguinea  of 
stagnant  water  (slightly  magnified). 


Fig.  66. — Protococcus  nivalis  of 
red  snow  (magnified). 


the  same  plant  which  was  green  the  day  before.  If 
there  is  a  thunderstorm  or  waterspout  which  draws 
up  the  red  water  from  the  ponds  and  reservoirs,  and 
discharges  it  in  the  form  of  rain  on  the  surrounding 
country,  we  hear  of  the  phenomenon  that  it  rains  blood, 
and  it  would  be  easy  to  find  in  the  drops  of  rain  the 
reddish  microbe  which  imparts  this  colour  to  them. 

In  northern  regions  the  snow  is  often  tinged  with 
the  colour  of  blood  by  an  analogous  Micrococcus,  which 


MICROBES,   OR  BACTERIA. 


129 


presents  the  same  transition  from  green  to  red  (Fig. 
6G).  Green-tinted,  snow  may  be  found  adjacent  to 
the  red  snow,  and  under  the  microscope  it  displays 
minute  green  globules,  identical,  except  in  colour,  with 
those  of  the  red-tinted  snow. 

The  variety  of  colour  in  these  microbes  is  extreme. 
MICTOCOCCUS  aurantiacus  gives  an  orange  colour   to 


gf»  •  ' 

~  ///  (i   W 

/I 


V  \  ^       ' 

^3*  \<, 

G 


Fig.  GI.—Racterium  cyanogenum,  microbe  of  blue  milk  (Neelsen).    It  is  probable 
that  several  different  forms  are  here  contused  under  this  name.    B,  zoogloea. 

bread  and  eggs ;  M.  chlorinus  is  grass-green ;  M.  cyanus 
is  of  a  beautiful  azure  blue ;  M.  violaceus  is  violet  or 
lilac,  and  M.  fulvus  is  rust-coloured.  These  have  all 
been  observed  on  food.  M.  candidus  forms  little 
white  patches  upon  cheese. 

The  genus  Bacterium  also  furnishes  its  contingent 
of    coloured  species ;    such   are    B.   xanthinwm   and 

r 


130          MICROBES,  FERMENTS,   AND   MOULDS. 

B.  cyanogenum,  which  give  respectively  a  yellow 
or  blue  colour  to  milk  (Fig.  67).  Peasants  say  that 
an  evil  eye  has  been  cast  upon  the  milk,  but  it  is 
easy  to  prove  that  the  development  of  these  microbes 
is  due  to  imperfect  cleansing  of  the  tin  milk-vessels, 
since  the  discolouration  ceases  when  greater  care  is 
taken  to  wash  and  scald  the  vessels. 

Bread  often  displays  microscopic  growths  of  a 
dark  green  or  orange  colour,  and  in  this  state  it 
cannot  be  introduced  into  the  stomach  without 
danger.  In  the  first  case  it  is  Bacterium  cerugi- 
nosum,  in  the  second  Micrococcus  aurantiacus.  The 
badly  made  and  badly  baked  bread  of  the  French 
peasants,  which  is  often  kept  for  a  fortnight  or  more, 
exposed  to  the  moisture  and  heat  which  favour  the 
development  of  these  microbes,  sometimes  displays 
the  first  of  these  changes;  the  second  is  particularly 
common  in  soldiers'  bread,  which  must  likewise  be 
baked  several  days  in  advance,  and  which  is  conveyed 
in  carts  exposed  to  the  weather.  Megnin  recently 
observed  a  cryptogamic  growth  of  this  kind  on  the 
bread  distributed  to  the  garrison  of  Vincennes. 

The  spores  of  these  microbes  are  found  in  flour, 
and  resist  a  temperature  of  120°,  while  they  are 
destroyed  by  that  of  140°.  Thus  they  are  no  longer 
found  in  the  crust,  of  which  the  temperature  rises 
to  200° ;  but  may  easily  subsist  in  the  much  lower 
temperature  of  the  crumb.  Hence  the  necessity  of 
only  using  flour  perfectly  free  from  germs. 


MICROBES,   OR  BACTERIA.  131 

The  pus  of  wounds  is  often  coloured  blue  by 
an  aerobic  micrococcus,  of  which  the  protoplasm  is 
colourless,  but  which  makes  a  colouring  matter 
called  pyocyanine,  and  this  gives  a  blue  tint  to  the 
lint  and  bandages  used  for  dressing  the  wound. 


XV.  THE  MICROBE  OF  BALDNESS. 

In  addition  to  the  numerous  parasitic  fungi  of 
skin  on  which  the  hair  grows  thickly,  which  we 
have  already  noticed,  the  human  hair  is  attacked 
by  a  true  microbe,  which  is,  according  to  the  re- 
searches of  Gruby,  Malassez  and  Thin,  the  cause  of 
Alopecia  areata,  one  form  of  baldness.  The  parasite 
has  the  appearance  of  a  micrococcus,  and  penetrates 
the  interior  of  the  hair,  which  is,  as  we  know,  hollow. 
The  hair  must  be  made  transparent  by  potash,  in  order 
to  see  the  microbe.  It  probably  penetrates  between 
the  bulb  and  the  hair-follicle  as  far  as  the  root,  is 
introduced  into  the  hair,  and  multiplies  and  gradually 
rises  higher  in  it,  until  the  substance  is  disorganized. 
This  microbe  has  been  called  Bacterium  decalvana. 


132          MICEOBES,  FEEMENTS,  AND  MOULDS. 


CHAPTER  IV. 

MICROBES  OF  THE  DISEASES  OF  OUR  DOMESTIC  ANIMALS. 

I.  ANTHRAX,  OR  SPLENIC  FEVER. 

THE  first  of  the  virulent  and  contagious  diseases  in 
which  the  presence  of  a  microbe  was  positively 
ascertained  was  anthrax,  or  splenic  fever,  which 
attacks  most  of  our  horned  animals,  and  especially 
cattle  and  sheep. 

As  early  as  1850,  Davaine  had  observed  the 
presence  of  minute  rods  in  the  blood  of  animals  which 
died  of  splenic  fever;  but  it  was  only  in  1863,  after 
Pasteur's  first  researches  into  the  part  played  by 
microbes  in  fermentations,  that  Davaine  suspected 
these  rods  of  being  the  actual  cause  of  the  disease. 
He  inoculated  healthy  animals  with  the  tainted  blood, 
and  thus  ascertained  that  even  a  very  minute  dose 
would  produce  a  fatal  attack  of  the  disease,  and  the 
rods,  to  which  he  gave  the  name  of  Bacteridia,  could 
always  be  discovered  in  enormous  numbers  in  the 
blood. 


ANTHRAX.  133 

The  microbe  so  named  by  Davaine  must  from  its 
characteristics  be  assigned  to  the  genus  Bacillus,  and 
is  now  termed  Bacillus  anthracis.  This  disease, 
which  affects  men  as  well  as  animals,  is  characterized 
by  general  depression,  by  redness  and  congestion  of 
the  eyes,  by  short  and  irregular  respiration,  and  by 
the  formation  of  abscesses,  which  feature,  in  the  case 
of  the  human  subject,  has  procured  for  it  the  name  of 
malignant  pustule.  The  disease  is  quickly  terminated 


Fig.  68. — Bacillus  anthracis  of  splenic  fever  in  different  stages  of  development: 
bacilli,  spores,  and  curled  filaments  (much  enlarged). 


by  death,  and  an  autopsy  shows  that  the  blood  is 
black,  that  intestinal  haemorrhage  has  occurred,  and 
that  the  spleen  is  abnormally  large,  heavy,  and  gorged 
with  blood ;  hence  the  name  of  splenic  fever.  The 
disease  is  generally  inoculated  by  the  bite  of  flies 
which  have  settled  upon  carcases  and  absorbed  the 
bacteria,  or  by  blood-poisoning  through  some  accidental 
scratch,  and  this  is  especially  the  case  with  knackers 


134          MICROBES,   FERMENTS,  AND  MOULDS. 

and  butchers  who  break  and   handle   the  bones  of 
animals  which  have  died  of  anthrax. 

The  period  of  incubation  is  very  short.  An  ox 
which  has  been  at  work  may  return  to  the  stall 
apparently  healthy.  He  eats  as  usual ;  then  lies  down 
on  his  side  and  breathes  heavily,  while  the  eyes  are 
still  clear.  Suddenly  his  head  drops,  his  body  grows 
cold ;  at  the  end  of  an  hour  the  eye  becomes  glazed ; 
the  animal  struggles  to  get  up,  and  falls  dead.  In 
this  case,  the  illness  has  only  lasted  for  an  hour  and 
a  half  (Einpis). 


Fig.  69  —Bacillus  anthracis,  produced  in  guinea-pig  by  inoculation:  corpuscles  of 
blood  and  bacilli. 

In  order  to  prove  that  the  disease  is  really  caused 
by  Bacillus  anthracis,  Pasteur  inserted  a  very  small 
drop  of  blood,  taken  from  an  animal  which  had 
recently  died  of  anthrax,  in  a  glass  flask  which  con- 
tained an  infusion  of  yeast,  neutralized  by  potassium 
and  previously  sterilized.  In  twenty-four  hours  the 
liquid,  which  had  been  clear,  was  seen  to  be  full  of 
very  light  flakes,  produced  by  masses  of  bacilli,  readily 


ANTHRAX.  135 

discernible  under  the  microscope.  A  drop  from  the 
first  flask  produced  the  same  effect  in  a  second,  and 
from  that  to  a  third,  and  so  on.  By  this  means  the 
organism  was  completely  freed  from  all  which  was 
foreign  to  it  in  the  original  blood,  since  it  is  calculated 
that  after  from  eight  to  ten  of  such  processes,  the 
drop  of  blood  was  diluted  in  a  volume  of  liquid 
greater  than  the  volume  of  the  earth.  Yet  the  tenth, 
twentieth,  and  even  the  fiftieth  infusion  would,  when 
a  drop  was  inserted  under  the  skin  of  a  sheep,  procure 
its  death  by  splenic  fever,  with  the  same  symptoms 
as  those  produced  by  the  original  drop  of  blood.  The 
bacillus  is,  therefore,  the  sole  cause  of  the  disease. 

These  cultures  have  often  since  been  repeated  by 
numerous  observers,  so  that  the  microbe  has  been 
studied  in  all  its  forms,  and  the  extent  of  its  poly- 
morphism has  been  ascertained.  At  the  end  of  two 
days  the  bacterium,  which,  while  still  in  the  blood, 
is  of  a  short,  abrupt  form,  displays  excessively  long 
filaments,  which  are  sometimes  rolled  up  like  a  coil 
of  string.  In  about  a  week  many  of  the  filaments 
contain  refracting,  somewhat  elongated  nuclei.  These 
nuclei  presently  form  chaplets,  in  consequence  of  the 
rupture  of  the  cell-wall  of  the  rod  which  gave  birth 
to  them ;  others,  again,  float  in  the  liquid  in  the  form 
of  isolated  globules.  These  nuclei  are  the  spores  or 
germs  of  the  microbes,  which  germinate  when  placed 
in  the  infusion,  become  elongated,  and  reproduce  fresh 
bacilli 


136          MICROBES,  FERMENTS,  AND  MOULDS. 

These  spores  are  much  more  tenacious  of  life  than 
the  microbes  themselves.  The  latter  perish  in  a  tempe- 
rature of  60°,  by  desiccation,  in  a  vacuum,  in  carbonic 
acid,  alcohol,  and  compressed  oxygen.  The  spores 
on  the  other  hand,  resist  desiccation,  so  that  they  can 
float  in  the  air  in  the  form  of  dust.  They  also  resist 
a  temperature  of  from  90°  to  95°,  and  the  effects  of  a 
vacuum,  of  carbonic  acid,  of  alcohol,  and  compressed 
oxygen. 

In  1873,  Pasteur,  aided  by  Chamberland  and  Koux, 
carried  on  some  experiments  on  a  farm  near  Chartres, 
in  order  to  discover  why  this  disease  is  so  common  in 
some  districts,  in  which  its  spread  cannot  be  ascribed 
to  the  bite  of  flies.  Grass,  on  which  the  germs  of 
bacteridia  had  been  placed,  was  given  to  the  sheep. 
A  certain  number  of  them  died  of  splenic  fever.  The 
glands  and  tissues  of  the  back  of  the  throat  were 
very  much  swelled,  as  if  the  inoculation  had  occurred 
in  the  upper  part  of  the  alimentary  canal,  and  by 
means  of  slight  wounds  on  the  surface  of  the  mucous 
membrane  of  the  mouth.  In  order  to  verify  the  fact, 
the  grass  given  to  the  sheep  was  mixed  with  thistles 
and  bearded  ears  of  wheat  and  barley,  or  other  prickly 
matter,  and  in  consequence  the  mortality  was  sensibly 
increased. 

In  cases  of  spontaneous  disease  it  was  surmised 
that  the  germs  which  were  artificially  introduced  into 
food  in  the  course  of  these  experiments,  are  found 
upon  the  grass,  especially  in  the  neighbourhood  of 


ANTHRAX.  137 

places  in  which  infected  animals  had  been  buried.  It 
was,  in  fact,  ascertained  that  these  germs  existed 
above  and  around  the  infected  carcases,  and  that  they 
were  absent  at  a  certain  distance  from  their  burial- 
place.  It  is  true  that  putrid  fermentation  destroys 
most  of  the  bacteria,  but  before  this  occurs  a  certain 
number  of  microbes  are  dispersed  by  the  gas  dis- 
engaged from  the  carcase;  these  dry  up  and  produce 
germs,  which  retain  their  vitality  in  the  soil  for  a 
long  while. 

The  mechanism  by  means  of  which  these  germs 
are  brought  to  the  surface  of  the  soil  and  on  to  the 
grass  on  which  the  sheep  feed  is  at  once  simple  and 
remarkable.  Earth-worms  prefer  soils  which  are  rich 
in  humus  or  decomposing  organic  substance,  and  seek 
their  food  round  the  carcase.  They  swallow  the  earth 
containing  the  germs  of  which  we  have  spoken,  which 
they  deposit  on  the  surface  of  the  soil,  after  it  has 
traversed  their  intestinal  canals,  in  the  little  heaps 
with  which  we  are  all  acquainted.  The  germs  do  not 
lose  their  virulence  in  their  passage  through  the 
worms'  intestines,  and  if  the  sheep  swallow  them 
together  with  the  grass  on  which  they  browse,  they 
may  contract  the  disease.  The  turning-up  of  the  soil 
by  the  spade  or  plough  may  produce  the  same  effect. 

A  certain  warmth  is  necessary  for  the  formation 
of  germs;  none  are  produced  when  it  falls  below  12°, 
and  the  carcases  buried  in  winter  are  therefore  less 
dangerous  than  those  buried  in  the  spring  and  sum- 


138          MICKOBES,  FERMENTS,  AND  MOULDS. 

mer.  It  is,  in  fact,  in  hot  weather  that  the  disease 
is  most  prevalent.  Animals  may,  however,  contract 
it  even  in  their  stalls  from  eating  dry  fodder  on  which 
germs  of  these  bacteria  remain. 

Pasteur  and  his  pupils  performed  an  experiment 
in  the  Jura  in  1879,  which  clearly  shows  that  the 
presence  of  germs  above  the  trenches  in  which  car- 
cases have  been  buried  is  the  principal  cause  of 
inoculation.  Twenty  oxen  or  cows  had  perished,  and 
several  of  them  were  buried  in  trenches  in  a  meadow 
where  the  presence  of  these  germs  was  ascertained. 
Three  of  the  graves  were  surrounded  by  a  fence, 
within  which  four  sheep  were  placed.  Other  sheep 
were  folded  within  a  few  yards  of  the  former,  but  in 
places  where  no  infected  animals  had  been  buried. 
At  the  end  of  three  days,  three  of  the  sheep  folded 
above  the  graves  had  died  of  splenic  fever,  while  those 
excluded  from  them  continued  to  be  healthy.  This 
result  speaks  for  itself. 

Malignant  pustule,  which  is  simply  splenic  fever, 
affects  shepherds,  butchers,  and  tanners,  who  handle 
the  flesh  and  hide  of  tainted  animals.  Inoculation 
with  the  bacillus  almost  always  occurs  in  consequence 
of  a  wound  or  scratch  on  the  hands  or  face.  In  Ger- 
many, fatal  cases  of  anthrax  have  been  observed,  in 
which  the  disease  has  been  introduced  through  the 
mouth  or  lungs,  as  in  the  case  of  the  sheep  observed 
by  Pasteur.  The  human  subject  appears,  however, 
to  be  less  apt  to  contract  the  disease  than  herbivora, 


ANTHRAX.  139 

since  the  flesh  of  animals  affected  by  splenic  fever, 
and  only  killed  when  the  microbe  is  fully  developed 
in  the  blood,  is  often  eaten  in  farmhouses.  In  this 
case  the  custom  prevalent  among  French  peasants  of 
eating  over-cooked  meat  constitutes  the  chief  safeguard, 
since  the  bacteria  and  their  germs  are  thus  destroyed. 


II.  VACCINATION  FOB  ANTHRAX. 

The  rapidity  with  which  anthrax  is  propagated 
by  inoculation  generally  renders  all  kinds  of  treat- 
ment useless;  if,  however,  the  wound  through  which 
the  microbe  is  introduced  can  be  discovered,  it  should 
be  cauterized  at  once.  This  method  is  often  successful 
in  man.  The  pustule  is  cauterized  with  red-hot  iron, 
or  with  bichloride  of  mercury  and  thymic  acid,  two 
powerful  antiseptics,  certain  to  destroy  the  bacteridium. 
It  is  expedient,  as  an  hygienic  measure,  to  burn  the 
tainted  carcases,  and  if  this  is  not  done,  they  should 
be  buried  at  a  much  greater  depth  than  is  usually  the 
case. 

But  the  preservative  means  on  which  chief  re- 
liance is  now  placed  is  vaccination  with  the  virus 
of  anthrax.  Pasteur  has  ascertained  that  when 
animals  are  inoculated  with  a  liquid  containing  bac- 
teridia  of  which  the  virulence  has  been  attenuated 
by  culture  carried  as  far  as  the  tenth  generation,  or 
even  further,  their  lives  are  preserved.  They  take 


140          MICROBES,   FERMENTS,   AND  MOULDS. 

the  disease,  but  generally  in  a  very  mild  form,  and  it 
is  an  important  result  of  this  treatment  that  they  are 
henceforward  safe  from  a  fresh  attack  of  the  disease ; 
in  a  word,  they  are  vaccinated  aga-inst  anthrax. 

In  the  cultures  prepared  with  the  view  of  attenu- 
ating the  microbe,  it  is  the  action  of  the  oxygen  of 
the  air  which  renders  the  bacteridium  less  virulent. 
It  should  be  subjected  to  a  temperature  of  from  42° 
to  43°  in  the  case  of  Bacillus  anthracis,  to  enable  it 
to  multiply,  and  at  the  same  time  to  check  the  pro- 
duction of  spores  which  might  make  the  liquid  too 
powerful.  At  the  end  of  the  week,  the  culture,  which 
at  first  killed  the  whole  of  ten  sheep,  killed  only  four 
or  five  out  of  ten.  In  ten  or  twelve  days  it  ceased 
to  kill  any ;  the  disease  was  perfectly  mild,  as  in  the 
case  of  the  human  vaccinia,  of  which  we  shall  speak 
presently.  After  the  bacteridia  have  been  attenuated, 
they  can  be  cultivated  in  the  lower  temperature  of 
from  30°  to  35°,  and  only  produce  spores  of  the  same 
attenuated  strength  as  the  filaments  which  form  them 
(Chamberland). 

The  vaccine  thus  obtained  in  Pasteur's  laboratory 
is  now  distributed  throughout  the  world,  and  has 
already  saved  numerous  flocks  from  almost  certain 
destruction.  Although  this  process  has  only  been 
known  for  a  few  years,  its  results  are  such  that  the 
gain  to  agriculture  already  amounts  to  many  thousands 
of  pounds. 

Toussaint  makes  use  of  a  slightly  different  mode 


ANTHRAX.  141 

of  preparing  a  vaccine  virus,  which  is,  however, 
analogous  to  that  of  Pasteur.  He  subjects  the  lymph 
of  the  blood  of  a  diseased  animal  to  a  temperature 
of  50°,  and  thus  transforms  it  into  vaccine.  Toussaint 
considers  the  high  temperature  to  be  the  principal 
agent  of  attenuation,  and  ascribes  little  or  no  im- 
portance to  the  action  of  the  oxygen  in  the  air. 

Chamberland  and  Roux  have  recently  made  re- 
searches with  the  object  of  obtaining  a  similar 
vaccine  by  attenuating  the  primitive  virus  by  means 
of  antiseptic  substances.  They  have  ascertained  that 
a  solution  of  carbolic  acid  of  one  part  in  six  hundred 
destroys  the  microbes  of  anthrax,  while  they  can  live 
and  flourish  in  a  solution  of  one  part  in  nine  hundred, 
but  without  producing  spores,  and  their  virulence  is 
attenuated  When  a  nourishing  broth  is  added  to 
a  solution  of  one  in  six  hundred,  the  microbe  can  live 
and  grow  in  it  for  months.  Since  the  chief  condition 
of  attenuation  consists  in  the  absence  of  spores,  this 
condition  seems  to  be  realized  by  the  culture  in  a 
solution  of  carbolic  acid,  one  in  nine  hundred,  and  it 
is  probable  that  a  fresh  form  of  attenuated  virus 
may  thus  be  obtained.  Diluted  sulphuric  acid  gives 
analogous  results. 

However  this  may  be,  the  vaccine  prepared  by 
Pasteur's  process  is  the  only  one  which  has  been 
largely  used,  and  which  has  afforded  certain  results  to 
cattle-breeders. 

Public    experiments,    performed    before    com  mis- 


142          MICROBES,   FERMENTS,   AND  MOULDS. 

sions  composed  of  most  competent  men,  have  clearly 
shown  the  virtue  of  the  protective  action.  In  the 
summer  of  1881,  the  initiation  was  taken  by  the 
Melun  Society  of  Agriculture.  Twenty-five  sheep  and 
eight  cows  or  oxen  were  vaccinated  at  Pouilly-le-Fort, 
and  then  re-inoculated  with  blood  from  animals  which 
had  recently  died  of  anthrax,  together  with  twenty- 
five  sheep  and  five  cows  which  had  not  been  previously 
vaccinated.  None  of  the  vaccinated  animals  suffered 
while  the  twenty-five  test  sheep  died  within  forty- 
eight  hours,  and  the  five  cows  were  so  ill  that  the 
veterinary  surgeons  despaired  of  them  for  several 
days. 

This  experiment  was  publicly  repeated  in  Sep- 
tember, 1881,  by  Thuillier,  Pasteur's  fellow- worker, 
whose  death  we  have  recently  had  to  deplore,  before  the 
representatives  of  the  Austro-Hungarian  Government ; 
and  again  near  Berlin,  in  1882,  before  the  representa- 
tives of  the  German  Government,  and  always  with 
the  same  success.  Up  to  April,  1882,  more  than 
130,000  sheep  and  2000  oxen  or  cows  had  been  vac- 
cinated ;  and  since  that  time  the  demand  for  vaccine 
from  Pasteur's  laboratory  has  reached  him  from  every 
quarter. 

III.  FOWL  CHOLERA. 

The  sickness  of  barn-door  poultry,  which  is  com- 
monly called  cholera,  is  caused  by  the  presence  in  the 


OTHER  DISEASES  OF  DOMESTIC  ANIMALS.      143 

blood  of  a  small  micrococcus  or  bacterium  in  the  form 
of  the  figure  8,  differing,  therefore,  in  form  from  Bacil- 
lus anthracis,  but  also  an  aerobie.  It  may  be  cultivated 
in  chicken-broth,  neutralized  by  potash,  while  it  soon 
dies  in  the  extract  of  yeast,  which  is  so  well  adapted 
to  Bacillus  anthracis. 

The  microbe  of  this  disease  may  also  be  attenuated 
by  culture,  and  it  may  be  done  more  easily  than  in 
the  case  of  anthrax,  since  it  is  not  necessary  to  raise 
the  temperature,  as  the  bacterium  of  fowl-cholera  does 
not  produce  spores  under  culture.  Pasteur  has  there- 
fore been  able  to  prepare  an  attenuated  virus  well 
adapted  to  protect  fowls  from  further  attacks  of  this 
disease. 

IY.  SWINE  FEVER. 

The  disease  affecting  swine,  which  is  called  rouget, 
or  swine  fever,  in  the  south  of  France,  has  been 
recently  studied  by  Detmers  in  the  United  States, 
where  it  is  also  very  prevalent,  and  by  Pasteur  in 
the  department  of  Vaucluse.  It  is  a  kind  of  pneumo- 
enteritis. 

These  observers  consider  that  the  disease  is  caused 
by  a  very  slender  microbe,  formed,  like  that  of  fowl- 
cholera,  in  the  shape  of  the  figure  8,  but  more  minute. 
Others  say  that  there  is  a  bacillus  which  was  observed 
by  Klein  as  early  as  1878  in  swine  attacked  by  this 
disease.  In  spite  of  the  apparent  contradiction,  it  is 


144          MICROBES,  FERMENTS,   AND  MOULDS. 

probable  that  we  have  only  two  forms  of  the  same 
microbe,  for  the  bacillus  in  Klein's  culture  at  first 
resembles  Bacterium  termo,  in  the  form  of  an  8,  before 
it  is  elongated  into  rods. 

Pasteur  has  succeeded  in  making  cultures  of 
microbes  in  the  figure  8.  He  has  inoculated  swine 
with  the  attenuated  form,  after  which  they  have  been 


Fig.  70.— Swine  fever:  section  of  a  lymphatic  gland,  showing  a  blood-vessel  filled  with 
microbes  (much  enlarged :  Klein). 

able  to  resist  the  disease,  so  there  is  reason  to  hope 
that  in  the  near  future  this  new  vaccine,  containing 
the  attenuated  microbe,  may  become  the  safeguard  of 
our  pig-sties. 


V.  OF  SOME  OTHER  DISEASES  PECULIAR  TO  DOMESTIC 
ANIMALS. 

An  epidemic  which  raged  in  Paris  in  1881  was 
called  the  typhoid  fever  of  horses,  and  was  fatal  to 
more  than  1500  animals  belonging  to  the  General  Om- 
nibus Company  in  that  city.  This  disease  is  also  pro- 


OTHER  DISEASES  OF  DOMESTIC  ANIMALS.       145 

duced  by  a  microbe,  with  which  Pasteur  was  able  to 
inoculate  other  animals  (rabbits) ;  for  this  purpose 
he  made  use  of  the  serous  discharge  from  the  horses' 
nostrils.  The  inoculated  rabbits  died  with  all  the 
symptoms  and  lesions  characteristic  of  the  disease. 

The  attenuation  of  this  microbe  by  culture  is 
difficult,  since  at  the  end  of  a  certain  time  the  action 
of  the  air  kills  it.  Pasteur  has,  however,  found  an 
expedient  by  which  to  accomplish  his  purpose.  When 
the  culture  is  shown  to  be  sterile  in  consequence  of 
the  death  of  the  microbe,  he  takes  as  the  mother 
culture  of  a  fresh  series  of  daily  cultures  the  one  which 
was  made  on  the  day  preceding  the  death  of  the  first 
mother  culture.  In  this  way  he  has  obtained  an 
attenuated  virus  with  which  to  inoculate  rabbits,  and 
the  same  result  might  undoubtedly  be  obtained  in 
the  case  of  horses. 

There  are  many  other  contagious  diseases  which 
affect  domestic  animals,  and  which  are  probably  due  to 
microbes,  such  as,  for  instance,  the  infectious  pneumonia 
of  horned  cattle.  This  was  probably  the  first  disease  in 
which  the  protective  effects  of  inoculation  were  tried 
according  to  Wilhelm's  method.  This  method  consisted 
in  making  an  incision  under  the  animal's  tail  with  a 
scalpel  dipped  in  the  purulent  mucus  or  blood  taken 
from  the  lung  of  a  beast  which  had  died  of  pneumonia ; 
sometimes  the  serous  discharge  from  the  swelling  under 
the  tail  of  an  inoculated  animal  was  used  for  others. 
Fever  and  loss  of  appetite  ensued,  lasting  from  eight 


146          MICROBES,   FERMENTS,  AND  MOULDS. 

to  twenty-five  days,  but  the  animal  was  afterwards 
safe  from  further  attacks  of  the  disease. 

Cattle  plague,  or  contagious  typhus,  is  likewise 
ascribed  to  the  presence  of  a  microbe  with  which  we 
are  as  yet  imperfectly  acquainted. 

Experimental  septicemia  is  entitled  to  special  men- 
tion, since  it  has  too  often  been  confounded  with 
anthrax,  and  has  been  unskilfully  produced  with  the 
intention  of  vaccinating  animals  in  accordance  with 
Pasteur's  process.  This  occurs  when  too  long  an 
interval  (twenty -four  hours)  elapses  after  the  death  of 


Fig.  71.— -Septic  vibrio,  bacillus  of  malignant  oedema  (Koch)  :    a,  taken  from  spleen  of 
guinea-pig;  b,  from  a  mouse's  lung. 

an  animal,  before  taking  from  it  the  blood  intended  for 
vaccine  cultures.  After  this  date  the  blood  no  longer 
contains  Bacillus  anthracis,  which  is  succeeded  by 
another  microbe  termed  Vibrio  septicus,  differing 
widely  from  the  anthrax  microbe  in  form,  habit,  and 
character  (Fig.  71).  Bacillus  anthracis  is  straight  and 
immobile,  while  the  septic  vibrio  is  sinuous,  curled, 
and  mobile.  Moreover,  it  is  anaerobic,  and  does  not 
survive  contact  with  the  air,  but  it  thrives  in  a  vacuum 
or  in  carbonic  acid.  Since  Bacillus  anthracis  is,  on 


OTHER  DISEASES  OF  DOMESTIC  ANIMALS.        147 

the  other  hand,  an  aerobie,  it  is  clear  that  the  two 
microbes  cannot  exist  simultaneously  in  the  blood  or 
in  the  same  culture  liquid. 

The  inoculation  with  this  fresh  microbe  is  no  less 
fatal;  its  action  is  even  more  rapid  than  that  of 
Bacillus  anthracis,  but  the  lesions  are  not  the  same ;  the 
spleen  remains  normal,  while  the  liver  is  discoloured. 

The  septic  vibrio  is  only  found  in  minute  quantities 
in  the  blood,  so  that  it  has  escaped  the  notice  of  many 
observers.  It  is,  however,  found  in  immense  numbers 
in  the  muscles,  in  the  serous  fluid  of  the  intestines,  and 
of  other  organs.  It  is  very  common  in  the  intestines, 
and  is  probably  the  beginning  of  putrefaction. 


VI.  RABIES. 

Rabies  is  a  canine  disease  which  is  communicated 
by  a  bite,  and  the  inoculation  of  man  and  other 
animals  by  the  saliva.  We  are  not  yet  precisely 
acquainted  with  the  microbe  which  causes  the  disease, 
but  Pasteur's  recent  researches  have  thrown  consider- 
able light  on  its  life-history,  which  is  still,  however, 
too  much  involved  in  obscurity. 

It  must  first  be  observed  that  the  hypothetical 
microbe  of  rabies,  which  no  one  has  yet  discovered, 
should  not  be  confounded  with  the  microbe  of  human 
saliva ;  this  is  found  in  the  mouths  of  healthy  persons, 
and  will  be  briefly  discussed  in  the  following  chapter. 


148          MICROBES,   FERMENTS,   AND  MOULDS. 

The  following  conclusions  are  the  result  of  Pasteur's 
researches  into  the  virus  of  rabies. 

This  virus  is  found  in  the  saliva  of  animals  and  men 
affected  by  rabies,  associated  with  various  microbes. 
Inoculation  with  the  saliva  may  produce  death  in  three 
forms:  by  the  salivary  microbe,  by  the  excessive 
development  of  pus,  and  finally  by  rabies. 

The  brain,  and  especially  the  medulla  oblongata,  of 
men  and  animals  which  have  died  of  rabies,  is  always 
virulent  until  putrefaction  has  set  in.  So  also  is 
the  spinal  cord.  The  virus  is,  therefore,  essentially 
localized  in  the  nervous  system. 

Rabies  is  rapidly  and  certainly  developed  by  tre- 
phining the  bones  of  the  cranium,  and  then  inocu- 
lating the  surface  of  the  brain  with  the  blood  or  saliva 
of  a  rabid  animal.  In  this  way  there  is  a  suppression 
of  the  long  incubation  which  ensues  from  simple 
inoculation  of  the  blood  by  a  bite  or  intra-venous 
injection  on  any  part  of  the  body.  It  is  probable  that 
in  this  case  the  spinal  cord  is  the  first  to  be  affected 
by  the  virus  introduced  into  the  blood ;  it  then  fastens 
on  its  tissues  and  multiplies  in  them. 

As  a  general  rule,  a  first  attack  which  has  not  proved 
fatal  is  no  protection  against  a  fresh  attack.  In  1881, 
however,  a  dog  which  had  displayed  the  first  symptoms 
of  the  disease  of  which  the  other  animals  associated 
with  him  had  died,  not  only  recovered,  but  failed  to 
take  rabies  by  trephining,  when  re-inoculated  in  1882. 
Pasteur  is  now  in  possession  of  four  dogs  which  are 


OTHER  DISEASES  OF  DOMESTIC  ANIMALS.        149 

absolutely  secured  from  infection,  whatever  be  the  mode 
of  inoculation,  and  the  intensity  of  the  virus.  All  the 
other  test  dogs  which  were  inoculated  at  the  same 
time  died  of  rabies.  In  1884,  Pasteur  found  the  means 
of  attenuating  the  virus.  For  this  purpose  he  has 
inoculated  a  morsel  of  the  brain  of  a  mad  dog  into  a 
rabbit's  brain,  and  has  passed  the  virus  proceeding 
from  the  rabbit  through  the  organism  of  a  monkey, 
whence  it  becomes  attenuated  and  a  protective  vaccine 
for  dogs.  This  is  the  first  step  towards  the  extinction 
of  this  terrible  disease. 


VII.  GLANDERS. 

This,  again,  is  a  disease  easily  transmitted  from 
horses  to  man.  Glanders,  or  farcy,  is  caused  by  the 
presence  of  a  bacterium,  observed  as  early  as  1868 
by  Christot  and  Kiener,  and  more  recently  studied  at 
Berlin  by  Schiitz  and  Lb'fler.  This  microbe  appears 
in  the  form  of  very  fine  rods  (bacillus)  in  the  lungs, 
liver,  spleen,  and  nasal  cavity.  Babes  and  Havas 
found  this  bacillus  in  the  human  subject  in  1881. 
Experimental  cultures  have  been  made  simultaneously 
in  France  and  Germany,  and  have  given  identical 
results. 

Bouchard,  Capitan,  and  Charrin  made  their  cultures 
in  neutralized  solutions  of  extract  of  meat,  maintained 
at  a  temperature  of  37°.  By.  means  of  successive 
sowings,  they  have  obtained  the  production  of  un- 


150          MICROBES,   FERMENTS,   AND  MOULDS. 

mixed  microbes,  presenting  no  trace  of  the  original 
liquid,  and  this  was  done  in  vessels  protected  from  air- 
germs.  These  cultures  may  be  carried  to  the  eighth 
generation. 

Asses  and  horses  inoculated  with  liquid  containing 
the  microbes  produced  by  this  culture  have  died  with 
the  lesions  characteristic  of  glanders  (glanderous 
tubercles  in  the  spleen,  lungs,  etc.).  Cats  and  other 
animals  which  have  been  inoculated  in  the  same  way 
die  with  glanderous  tubercles  in  the  lymphatic  glands 
and  other  organs. 

It  follows  from  these  experiments  that  the  microbe 
which  causes  this  disease  is  always  reproduced  in  the 
different  culture  liquids  with  its  characteristic  form 
and  dimensions  ;  that  uni-ungulates  can  be  inoculated 
with  it,  as  well  as  man  and  other  animals.  In  fact,  this 
microbe  is  the  essential  cause  of  the  disease. 


VIII.  PEBRINE  AND  FLACHERIE,  DISEASES  AFFECTING 
SILKWORMS. 

We  have  already  spoken  of  muscardine,  a  silk- 
worm's disease  produced  by  a  microscopic  fungus; 
two  other  diseases  are  caused  by  distinct  microbes,  of 
which  we  must  shortly  speak. 

Pebrine. — In  the  silkworm  nurseries,  in  which  this 
disease  prevails,  the  silkworms  which  issue  from  the 
eggs,  technically  called  seed,  are  slowly  and  irregularly 
developed,  so  as  to  vary  greatly  in  size.  Many  die 


OTHER  DISEASES  OF  DOMESTIC  ANIMALS.       151 

young,  and  those  which  survive  the  fourth  moult 
shrink  and  shrivel  away ;  they  can  hardly  creep  on  to 
the  heather  to  spin  their  cocoon,  and  produce  scarcely 
any  silk. 

On  an  examination  of  the  worms  which  have  died 
of  this  disease,  De  Quatrefages  ascertained  the  presence 
of  minute  stains  on  the  skin  and  in  the  interior  of 
the  body,  which  he  compared  to  a  sprinkling  of 
black  pepper;  hence  the  name  pebrine.  Under  the 
microscope  these  stains  assume  the  form  of  small 
mobile  granules  like  bacteria,  which  Cornalia  termed 
vibratile  corpuscles,  on  account  of  their  movements. 
Finally,  Osimo  and  Vittadini  ascertained  the  existence 
of  these  corpuscles  in  the  eggs,  and  consequently 
showed  that  the  epidemic  might  be  averted  by  the 
sole  use  of  healthy  eggs,  of  which  the  soundness 
should  be  established  by  microscopic  examination. 

It  was  at  about  this  date,  1865,  that  Pasteur  under- 
took the  exhaustive  study  of  pebrine;  but  Be'champ 
was  the  first  to  pronounce  the  disease  parasitic, 
resembling  muscardine  in  this  respect,  and  caused  by 
the  attacks  of  a  microbe — or  microzyma,  to  adopt 
Bechamp's  name — of  which  the  germ  or  spore  is  derived 
from  the  air,  at  first  attacking  the  silkworm  from 
without,  but  multiplying  in  its  interior,  and  developing 
with  its  growth,  so  that  the  infected  moth  is  unable 
to  lay  its  eggs  without  depositing  the  spores  of  the 
microbe  at  the  same  time,  and  thus  exposing  the 
young  grub  to  attack  as  soon  as  it  is  born.  Pasteur's 


152          MICROBES,  FERMENTS,  AND  MOULDS. 

own    researches    soon    induced    him    to    adopt    the 
same  view. 

The  pebrine  microbe  was  long  regarded  as  a  true 

bacterium,  successively  described  as  Bacterium  bom- 

^  bycis,  Nosema  bombycis  (Fig.  72),  and 

<3  0   ^        Panistophyton  ovale.    Balbiani's  recent 

^  0^0  ^      researches  tend  to  show  that  it  should 

n  °Q  ^  O  Q       be  assigned    to    another  group,   much 

0   *  nearer    to    animals,     and    designated 


Fig.    72.  —  Nosema 
bombycis,  pebrine 

Cx  5°°          Sporozoaria.  —  These   protista,   still 


regarded  as  plants  by  many  naturalists, 
chiefly  differ  from  bacteria  by  their  mode  of  growth 
and  reproduction,  in  which  -*they  resemble  the  para- 
sitic protozoaria,  termed  Psorospermia,  Coccidies,  and 
Gregarinidce. 

In  Sporozoaria,  growth  by  fission,  the  rule  in  all 
bacteria,  has  not  been  observed  ;  this  distinction  is 
fundamental.  Sporozoaria  multiply  by  free  spore- 
formation  in  a  mass  of  sarcode  substance  (protoplasm), 
resulting  from  the  encysting  of  the  primitive  corpuscles 
(mother-cells).  The  formation  of  numerous  spores 
may  be  observed  within  the  mother-cells,  having  the 
appearance  of  pseudonavicellce  or  spores  of  gregari- 
nidaeand  psorospermia  (parasites  of  vertebrate  animals). 
Balbiani  forms  these  organisms,  which  are  found  in 
many  insects,  into  a  small  group,  which  he  terms 
Mwrosporidia. 

The  ripe   spores   are   the  vibratile   corpuscles   of 


OTHER  DISEASES  OF  DOMESTIC  ANIMALS.        153 

Cornalia.  They  closely  resemble  the  spores  of  some 
bacilli  (B.  amylobacter,  for  instance),  and  their  germi- 
nation is  likewise  effected  by  perforation  of  the  spore 
at  one  end,  and  issue  of  the  protoplasm  from  the 
interior.  This,  however,  does  not  issue  in  a  rod-like 
form  (Bacillus),  but  in  that  of  a  small  protoplasmic 
mass,  with  amoeboid  movements,  a  characteristic  not 
observed  in  any  bacterium  (Balbiaui). 

The  other  species  of  silkworms  which  have  been 
recently  introduced,  notably  the  oak  silkworm  from 
China  (Attacus  Pernyi),a,Te  attacked  by  microsporidia 
analogous  to  those  of  pebrine. 

Pasteur  has  indicated  the  mode  of  averting  the 
ravages  of  this  disease.  He  has  thus  addressed  the 
breeders:  "If  you  wish  to  know  whether  a  lot  of 
cocoons  will  yield  good  seed,  separate  a  portion  of  them 
and  subject  them  to  heat,  which  will  accelerate  the 
escape  of  the  moth  by  four  or  five  days,  and  examine 
them  under  the  microscope  to  ascertain  whether  cor- 
puscles of  pebrine  are  present.  If  they  are,  send  all  the 
cocoons  to  the  silk  factory.  If  they  are  not  diseased, 
allow  them  to  breed,  and  the  seed  will  be  good  and 
will  hatch  out  successfully.  In  a  word,  start  with 
absolutely  healthy  seed,  produced  by  absolutely  pure 
ts,  and  rear  them  under  such  conditions  of 
cleanliness  and  isolation  as  may  ensure  immunity 
from  infection." 

When  the  disease  is  developed,  fumigation  with 
sulphurous  acid  is  recommended,  or  preferably  with 


abson 
paren 


154:          MICKOBES,    FERMENTS,  AND  MOULDS. 

creosote  or  carbolic  acid,  which  do  not  affect  the  silk- 
worms (Bechamp),  and  which  hinder  the  development 
of  microsporidia.  These  fumigations  likewise  keep 
the  litter  from  becoming  corrupt,  and  in  a  properly 
conducted  nursery  the  litter  is  kept  dry. 

Flacherie.  —  Wrongly  confounded  with  pebrine,  the 
disease  flacherie  is  still  more  destructive  to  silkworms. 
The  symptoms  are  remarkable.  The  rearing  of  silk- 
worms often  goes  on  regularly  up  to  the  fourth  moult, 
and  success  seems  assured,  when  the  silkworms  suddenly 
cease  to  feed,  avoid  the  leaves,  become  torpid,  and 
perish,  while  still  retaining  an  appearance  of  vitality, 
so  that  it  is  necessary  to  touch  them  in  order  to  ascer- 
tain that  they  are  dead.  In  this  state  they  are  termed 
morts-flats.  A  few  days,  sometimes  even  a  few  hours, 
suffice  to  transform  the  most  flourishing  nursery  into 
a  charnel-house. 

Pasteur  examined  these  morts-flats,  and  found  that 

the  leaves  contained  in  the  stomach  and  intestine  were 

full  of  bacteria,  resembling  those  which  are  developed 

when  the  leaves  are  bruised    in 

0  o°Q^  a  glass  of  water  and  left  to  putrefy 

0*o0°  '   \    0°°       (Fig-  73).    In  a  healthy  specimen, 

°°  of  good  digestion,  these  bacteria 


£    are  never  found.     It  is  therefore 
iam')-        evident  that  the  disease  is  owing 
to  bad  digestion,  and  becomes  rapidly  fatal  in  animals 
which  consume  an  enormous  amount  of  food,  and  do 
nothin^  but  eat  from  morning  to  night.    The  digestive 


OTHER  DISEASES  OF  DOMESTIC  ANIMALS.        155 

ferments  of  unhealthy  silkworms  do  not  suffice  to 
destroy  the  bacteria  of  the  leaves,  nor  to  neutralize 
their  injurious  effects. 

These  bacteria  are  really  the  cause  of  the  disease, 
for  if  even  a  minute  quantity  of  the  leaves  taken  from 
the  intestine  of  diseased  silkworms  be  given  to  healthy 
specimens,  they  soon  die  of  the  same  disease.  It  is, 
therefore,  essentially  contagious,  and  in  order  to  prevent 
the  diseased  silkworms  from  contaminating  the  healthy 
by  soiling  the  leaves  on  which  the  latter  are  about  to 
feed,  as  much  space  should  be  assigned  to  them  as 
possible. 

Good  seed  should  also  be  selected,  since  it  has  been 
ascertained  that  some  lots  of  seed  are  more  liable  to 
the  disease  than  others.  The  affection  does  not  indeed 
begin  in  the  egg,  as  in  pebrine,  but  the  question  of 
heredity  comes  in.  It  is  clear  that  when  a  silkworm 
has  been  affected  by  flacherie  without  dying  of  it,  its 
eggs  will  have  little  vitality,  and  the  grubs  which  issue 
from  them  will  be  predisposed  by  their  feeble  constitu- 
tion to  contract  the  disease. 


lot)          MiCEOBES,  JfEKMEUTfcJ,  AND  MOULDS* 


CHAPTER  V. 

THE  MICROBES  OF  HUMAN  DISEASES. 

I,  MICROBES  OF  AIR,  EARTH,  AND  WATER. 

IT  is  generally  admitted  that  the  large  majority  of 
epidemic  and  contagious  diseases  which  affect  men 
and  animals  are  caused  by  the  introduction  of  certain 
kinds  of  microbes  into  the  organism.  In  reply  to  the 
question  how  these  microbes  are  introduced  into  the 
body,  and  where  they  are  before  entering  it,  it  is  easy 
to  show  that  these  microbes  exist  in  immense  numbers 
— they  or  their  spores — in  the  air  we  breathe,  in  the 
water  we  drink,  in  the  ground  on  which  we  tread, 
and  whence  there  rises,  whenever  it  is  dry,  a  fine  dust 
charged  with  all  sorts  of  germs,  which  penetrate 
together  with  the  air  into  our  mouths  and  lungs. 

For  a  long  while  we  were  almost  completely 
ignorant  of  the  conditions  of  existence  of  these 
microbes  when  they  are  in  the  soil  or  water.  The 
recent  researches  of  Zopf,  a  German  botanist,  tend  to 
show  that  among  the  inferior  algsD  termed  Bacteria 


THE  MICKOBES  OF  HUMAN  DISEASES.  157 

or  Schizophyta,  there  is  a  very  remarkable  dimorphism 
of  mode  and  habitat.  In  Beggiatoa,  of  sulphurous 
waters,  for  instance,  and  in  Cladothrix,  which  forms  a 
whitish  pellicle  on  the  surface  of  putrefying  liquids, 
Zopf  has  found,  under  certain  conditions,  all  the  forms 
designated  as  Micrococcus,  Bacillus,  Leptothrix,  and 
Bacterium;  that  is,  microbes  strictly  so  called,  in- 
cluding those  which  are  the  producing  agents  of 
contagious  diseases. 

Where  these  algae  are  found  in  water  or  on  a  damp 
soil,  conditions  of  existence  favourable  to  their  develop- 
ment, there  they  live  and  multiply.  But  when  the 
soil  dries  up,  when  a  river  returns  to  its  bed  after 
a  flood,  or  a  marsh  disappears  in  consequence  of  the 
evaporation  of  its  waters,  all  these  algae  give  forth 
dormant  spores,  destined  to  ensure  their  propagation. 
We  have  described  the  formation  of  these  spores  by 
concentration  of  the  protoplasm  in  the  interior  of 
each  cell ;  in  this  form  their  volume  is  very  small,  and 
they  are  extremely  light,  so  that  as  soon  as  they  are 
desiccated,  and  then  only,  these  spores  are  carried 
away  by  the  slightest  breeze  and  borne  to  great  dis- 
tances. These  are  termed  air-germs. 

When  these  moving  germs  encounter  a  favourable 
medium,  at  once  moist  and  warm,  such  as  the  human 
mouth  or  lungs,  they  fasten  there  and  are  immediately 
developed,  first  in  the  form  of  Micrococcus,  then  of 
that  of  Bacterium,  Bacillus,  or  Leptothrix,  according 
to  the  species  to  which  the  spore  in  question  belongs. 


158          MICROBES,  FERMENTS,  AND  MOULDS. 

Schizophyta  may  therefore  have  two  very  different 
modes  of  existence,  comparable  to  the  hetersecia  (change 
of  habitat)  and  dimorphism  of  the  fungi  Ascomycetes 
and  Basidiomycetes.  Schizomycetes  however,  although, 
like  fungi,  they  obtain  their  nourishment  from  organic 
substances  which  have  been  already  elaborated,  are 
not  true  parasites  in  the  first  stage  of  their  existence, 
during  which  stage  they  live  freely  in  the  water,  or  on 
the  damp  soil.  They  become  true  parasites  when  they 
penetrate  into  the  blood  and  tissues  of  man,  in  which 
they  necessarily  live  at  the  expense  of  their  host. 

Hence  it  may  be  seen  why  half-dried  marshes, 
meadows  from  which  a  river  has  retreated  in  order 
to  return  to  its  bed,  great  excavations  of  the  soil 
necessary  in  railway -cuttings,  etc.,  become  the  source 
of  a  large  number  of  epidemic  or  contagious  diseases. 
In  all  these  places  the  subsiding  waters  have  left 
Schizophyta,  or  microbes  in  a  dried  state,  and  these 
are  soon  transformed  into  dormant  spores,  which  are 
diffused  through  the  air  and  enter  the  mouth  and 
lungs  of  men  living  near  the  rivers  and  marshes,  or 
who  are  working  on  the  railway-cutting.  The  soil 
which  has  remained  undisturbed  for  a  long  while  is 
full  of  dormant  spores,  drawn  into  it  by  the  rain  to 
a  greater  or  less  depth;  these  may  preserve  their 
vitality  for  many  years,  waiting  for  the  favourable 
medium,  which  leads  to  their  fresh  development. 

An  acquaintance  with  air-germs,  with  the  microbes 
of  earth  and  water,  has  therefore  become  indispensable 


THE  MICROBES  OF  HUMAN  DISEASES. 


159 


to  the  physician  and  to  the  professor  of  hygiene,  who 
are  anxious  to  decide  on  the  precise  cause  of  great 
epidemics  in  order,  if  possible,  to  foresee  and  avert 
them.  This  new  branch  of  meteorology  has  been 
termed  atmospheric  micrography,  since  it  necessarily 
involves  the  use  of  the  microscope. 

The  Microbes  of  the  Atmospfiere. — In  the  observa- 
tory of  Montsouris,  Paris,  there  is  now  a  special 
laboratory  under  the  direction  of  Miquel,  with  the 
object  of  studying  the  living  organisms  of  the  air, 
of  establishing  statistics  of  their  times  and  seasons, 


Figs.  74,  75. — Microbes  and  spores  of  atmospheric  dust,  mixed  with  amorphous 
particles,  and  collected  by  the  atiroscope. 

and  of  drawing  general  conclusions  as  to  the  hygienic 
condition  of  the  air,  according  as  it  is  more  or 
less  charged  with  the  microbes  and  spores  which 
are  factors  of  disease.  This  laboratory  is  provided 
with  the  apparatus  necessary  for  such  kinds  of 
research. 

The  first  of  these  apparatus  serves  to  collect  the 
living  organisms  which  are  always  mingled  with  a 
large  amount  of  inert  dust  (Figs.  74,  75).  The 


160  MICROBES,   FERMENTS,  AND  MOULDS. 

apparatus  is  founded  on  the  principle  of  the  aeroscope, 
invented  by  Pouchet  for  the  examination  of  air-dust. 
It  consists  of  a  small  cylinder  in  which  a  current  of 
air  is  produced  by  means  of  an  aspirator,  on  which 
running  water  acts,  similar  to  those  in  use  in  all 
laboratories  of  physics  and  chemistry.  A  thin  plate  of 
glass,  which  has  on  it  a  layer  of  glycerine,  is  placed 
at  the  bottom  of  the  cylinder,  so  as  to  intercept  the 
current  of  air  and  arrest  the  dust.  The  apparatus 
employed  by  Miquel  at  Montsouris  is  only  a  modifica- 
tion and  improvement  of  the  one  devised  by  Pouchet. 
The  glass  slide  is  then  transferred  to  the  objective 
of  the  microscope  in  order  that  the  dust  deposited 
on  it  may  be  examined. 

This  process  has  enabled  Miquel  to  define  the  laws 
which  rule  the  appearance  of  microbes  in  the  atmo- 
sphere, and  he  has  been  able  to  calculate  their  number 
in  a  given  volume  of  air.  With  respect  to  such  fungi 
and  algae  as  live  in  our  houses  (moulds),  and  on  our 
roofs,  walls,  and  on  damp  ground  (such  algae  as  Peni- 
cillium,  Protococcus,  Oklorococcus,  etc.),  he  has  arrived 
at  the  following  results,  as  far  as  Montsouris,  the  site 
of  his  experiments,  is  concerned. 

Few  in  number  in  January  and  February,  the 
number  of  mould-spores  further  diminishes  in  March, 
and  rises  again  in  April,  May,  and  June,  in  which 
month  the  maximum  is  attained.  The  decrease  is  slow 
up  to  October,  more  marked  in  November,  and  the 
minimum  is  observed  in  December.  In  this  case  the 


THE  MICROBES  OF  HUMAN  DISEASES.  161 

influence  of  rain  and  damp  is  very  marked.  In  winter 
the  average  number  of  spores  in  every  cubic  metre  of 
air  does  not  exceed  7000,  while  in  June  it  rises  to 
35,000. 

In  summer,  however,  when  the  temperature  is 
very  high,  the  number  of  spores  is  not  great ;  for  this 
reason,  that,  in  spite  of  the  heat,  the  air  is  moist,  and 
the  spores  settle  on  the  ground,  plants,  or  other  objects, 
instead  of  floating  in  the  air.  On  the  other  hand,  in 
winter,  since  very  cold  weather  is  generally  dry,  the 
number  of  air-germs  increases. 

In  summer,  storms  only  purify  the  air  for  a  very 
short  time ;  within  fifteen  or  eighteen  hours  after  the 
rain,  the  germs  reappear,  and  are  five  to  ten  times 
more  numerous  than  before.  It  seems  that  storms 
give  an  energetic  impulse  to  the  production  of  moulds. 

If  we  turn  to  consider  microbes,  strictly  so  called, 
or  the  bacteria  which  are  the  causes  of  malignant 
diseases,  research  becomes  more  difficult,  on  account 
of  their  smaller  size  and  great  transparency.  An 
expedient  is  necessary  to  reveal  their  presence  and 
enable  us  to  count  them  accurately:  this  expedient 
consists  in  staining  them  by  various  processes,  of 
which  we  shall  speak  when  we  come  to  discuss  the 
micrographic  study  of  drinking-water.  Miquel  prefers 
the  process  of  filtration  of  the  air  invented  by 
Pasteur,  which  consists  in  passing  the  air  and  aqueous 
vapour  into  such  sterilized  liquids  as  are  favourable 
to  the  nutrition  of  microbes. 


162          MICROBES,   FERMENTS,   AND  MOULDS. 

Sterilized  Flasks. — Pasteur  has  shown  that  air  may 
be  deprived  of  all  its  germs  by  being  passed  through 
a  capillary  tube,  turned  back  upon  itself.  He  takes 
a  glass  flask  and  draws  out  its  neck  so  as  to  form 
a  long  tube,  which  is  bent  in  different  directions 
(Fig.  76).  The  prolonged  application  of  heat  expels 
the  air  contained  in  the  flask,  which  is  therefore 
sterilized,  and  it  is  then  allowed  to  cool  slowly.  A 


I 

Fig.  76. — Pasteur's  flask,  with  bent  tube,  containing  a  culture  liquid,  sterilized. 

hot  culture  liquid  may  now  be  put  into  the  flask.  It 
must  be  ascertained,  by  keeping  the  flask  at  a  tem- 
perature of  36°  for  several  days,  that  the  liquid  is 
completely  sterilized.  The  culture  flasks  are  thus 
fitted  to  receive  the  air  which  is  to  be  the  object  of 
study,  together  with  the  spores  contained  in  it. 

Culture  liquids. — There  is  a  considerable  variety 
of  culture  liquids  :  Pasteur's  mineral  solution,  infusion 
of  hay  or  turnips,  neutral  urine,  chicken-broth,  beef- 
tea,  etc.  They  should  be  plunged  in  a  bath  heated 
to  a  temperature  of  150°  to  180°,  since  some  spores 


THE  MICROBES  OF  HUMAN  DISEASES.  163 

are  capable  of  resisting  a  prolonged  boiling  at  a 
temperature  of  100° ;  they  still  live  and  are  capable 
of  germinating  and  multiplying  when  the  liquid  is 
cooled. 

Culture  liquids  may  also  be  sterilized  without 
the  use  of  heat,  which  to  some  extent  affects  their 
nature,  by  filtering  them  through  a  porous  substance — 
biscuit- ware,  or  a  mixture  of  plaster  and  amianthus, 
etc.  A  more  perfect  apparatus  is  employed  by  Miquel, 
consisting  of  a  filter  of  very  thick  paper,  through 
which  the  liquid  is  forced  by  the  simultaneous  action 
of  a  vacuum  on  one  side,  and  of  strong  pressure  on 
the  other. 

For  the  artificial  culture  of  microbes,  solid  or 
partially  solid  substances  are  by  preference  often  used, 
such  as  gelatine,  or  slices  of  potatoes,  carrots,  hard 
eggs,  etc.,  prepared  in  different  ways  and  sterilized 
before  use.  We  cannot  here  describe  in  detail  all  the 
processes  employed  and  the  precautions  necessary  in 
order  to  avoid  error.  We  must  content  ourselves  with 
giving  the  results  obtained  by  Miquel. 

There  are  on  an  average  80  bacteria  in  a  cubic 
metre  of  Montsouris  air.  A  hundred  of  these  bacteria 
includes  66  Micrococci,  21  Bacteria  and  13  Bacilli 
In  rain  water  there  is  a  different  proportion :  28 
Micrococci,  9  Bacteria,  63  Bacilli.  At  the  beginning 
of  a  thunderstorm,  the  rain-water  includes  a  consider- 
able number,  about  15  to  the  cubic  centimetre;  then 
the  number  diminishes,  but  Miquel  states  that  "  after 


164          MICEOBES,   FEKMENTS,   AND  MOULDS. 

two  or  three  days  of  damp,  rainy  weather,  the  rain- 
water often  contains  more  bacteria  than  when  it  began 
to  fall.  Since  the  atmosphere  is  then  excessively  pure, 
it  seems  that  the  bacteria  are  able  to  live  and 
multiply  in  the  clouds,  or  else  that  the  clouds,  in 
their  passage  through  space,  take  up  a  varying  con- 
tingent of  germs." 

The  maximum  of  air-germs  is  observed  in  autumn, 
the  minimum  in  winter;  thus,  50  bacteria  were  counted 
in  December  and  January,  only  33  in  February,  105 
in  May,  50  in  June,  and  170  in  October. 

Inversely  to  what  occurs  with  moulds,  the  number 
of  bacteria,  low  in  rainy  weather,  rises  when  all 
moisture  has  disappeared  from  the  surface  of  the  soil. 
The  effect  of  dryness  is  greater  than  that  of  warmth. 
This  explains  the  scarcity  of  bacteria  after  the  great 
rains  of  February,  April,  and  June.  A  long  drought 
is,  however,  unfavourable  to  their  development. 

Miquel's  experiments  lead  him  to  conclude  that 
dew,  the  evaporation  from  the  soil,  is  never  charged 
with  spores.  The  dry  dust  in  the  neighbourhood  of 
inhabited  places,  and  especially  of  hospitals,  is,  on  the 
other  hand,  charged  with  microbes.  In  the  centre  of 
Paris,  for  example,  in  the  Rue  de  Eivoli,  there  are 
nine  or  ten  times  as  many  microbes  in  the  atmosphere 
as  in  the  neighbourhood  of  the  fortifications.  In  the 
Montsouris  Observatory,  south  of  Paris,  the  north 
winds  bring  many  more  bacteria  than  the  south  winds. 
The  most  impure  wind  comes  from  the  hills  of  Villette 


THE  MICROBES  OF  HUMAN  DISEASES.  165 

and  Belleville,  crowded  and  populous  quarters,  in  which 
are  also  cemeteries  and  slaughter-houses. 

It  has  long  been  established  that  the  air  is  much 
purer  on  high  mountains  or  on  the  sea,  than  in  plains 
and  in  the  vicinity  of  inhabited  places.  If  glass  flasks 
which  have  been  previously  sterilized  and  deprived 
of  air  are  taken  to  a  great  height  on  the  Alps  or 
Pyrenees,  and  then  filled  with  air,  it  will  be  difficult 
to  detect  any  microbes,  and  the  few  which  may  be 
found  are  possibly  brought  by  the  observer.  So 
again,  on  the  top  of  the  Pantheon,  a  cubic  metre  of 
air  only  contains  28  microbes,  while  45  are  found  hi 
the  park  of  Montsouris,  and  462  in  the  centre  of 
Paris. 

The  Microbes  of  Running  and  Drinking  Water. — 
Water,  whatever  be  its  source,  contains  many  more 
microbes  than  air.  They  are  even  found  in  spring- 
water  taken  from  its  source,  which  shows  that  they 
exist  in  the  interior  of  the  earth.  The  following  is 
Miquel's  estimate,  which  will  give  an  idea  of  the 
quantity  of  microbes  found  in  Paris  water,  taken  from 
different  places : — 

Source  of  water.  No.  of  microbes 

to  the  litre. 

Condensed  aqueous  vapour 900 

Water  from  drain,  Asuierea 48,000 

Rain-water      64,000 

Vanne  water  (Montrouge  basin)       248,000 

Seine  water  (from  Bercy,  above  Paris)      4,800,000 

Seine  water  (from  Asnieres,  below  Porid) 12,800,000 

Sewer-water  (from  Clicby) 80,000,000 


166          MICROBES,   FERMENTS,   AND  MOULDS. 

These  numbers  are  the  minima.  The  putrefaction 
of  stagnant  sewer- water  produces  germs  from  which, 
in  a  few  days,  microbes  are  multiplied  by  thousands. 

Certes,  in  France,  and  Maggi,  in  Italy,  have  lately 
been  occupied  with  the  micrographic  study  of  drink- 
ing-water. These  observers  reveal  the  presence  of 
microbes  in  the  water  under  examination  by  means 
of  staining  reagents.  The  reagent  most  in  use  is  a 
1'5  per  cent,  solution  of  osmic  acid  (Certes).  Osmic 
acid  kills  the  microbes  without  changing  their  form, 
and  precipitates  them  to  the  bottom  of  the  glass 
vessel,  whence  it  is  easy  to  collect  them.  A  cubic 
centimetre  of  the  solution  suffices  for  30  or  40  cubic 
centimetres  of  water.  It  is  allowed  to  settle,  then 
the  liquid  is  poured  off,  and  the  thick,  dark-coloured 
deposit  which  remains  consists  of  all  the  organisms 
previously  diffused  in  the  liquid,  and  may  be  examined 
under  the  microscope.  The  only  drawback  to  the 
use  of  this  reagent  is  the  high  price  of  osmic  acid, 
a  matter  worth  consideration  in  the  extensive  and 
comparative  researches  necessary  in  these  cases. 
Maggi  obtained  analogous  results  with  chloride  of 
palladium,  and  Certes  with  iodide  of  glycerine,  and 
alcoholic  solutions  of  cyanine,  gentian,  etc. ;  but  none 
of  these  reagents  are  as  efficient  as  osmic  acid,  of 
which  the  effect  is  more  precise,  constant,  and  durable. 

Microbes  of  the  Soil. — The  presence  of  microbes  in 
the  soil  has  been  proved  by  Pasteur  and  his  fellow- 
workers,  Charnberland  and  Roux,  in  the  researches  into 


THE  MICROBES  OF  HUMAN  DISEASES.  167 

the  nature  of  anthrax,  of  which  we  have  spoken  above. 
These  observers  collected  earth  in  the  neighbourhood  of 
trenches  in  which  animals  which  had  died  of  anthrax 
had  been  buried.  a?id  found  that  not  only  on  the  surface, 
but  at  some  depth,  this  earth  was  full  of  bacteridia 
(Bacillus  anthracis),  and  also  of  many  other  microbes 
or  germs,  of  which  the  inoculation  might  produce  more 
or  less  dangerous  diseases  in  animals.  In  order  to 
procure  earth  in  a  more  perfect  state  of  division,  it 
occurred  to  Pasteur  to  collect  the  excrement  of  earth- 
worms, which  consists  almost  exclusively  of  clay,  rich 
in  humus  or  vegetable  earth,  on  which  the  worms 
are  nourished.  This  earth,  after  passing  through  the 
intestinal  canal  of  worms,  still  contains  microbes  which 
have  not  lost  their  virulence.  As  we  have  already 
said,  spring  water,  on  issuing  from  the  soil,  contains 
microbes  which  it  has  acquired  in  filtering  through 
geological  layers;  and  we  have  also  mentioned  the 
living  microbes  of  chalk,  dating,  as  Be'charnp  believes, 
from  the  secondary  epoch. 

Telluric  and  Diblastic  Theories. — Hence,  it  is  in- 
telligible that  a  theory  should  have  been  formed, 
ascribing  most  epidemic  diseases  to  the  influence  of 
microbes  of  the  soil,  which  can  at  a  given  moment 
enter  the  human  body,  first  by  penetrating  into  the 
lungs  and  digestive  organs,  and  thence  into  the  blood. 

Two  German  discoverers,  Pettenkofer  and  Nageli, 
set  forth  this  telluric  theory  of  disease,  and  several 
facts  confirm  it.  It  explains  why  intermittent  fever  or 


168          MICROBES,   FERMENTS,  AND  MOULDS. 

malaria  only  prevails  in  marshy  countries  when  the 
marshes  are  partially  dry,  and  especially  in  summer. 
In  order  to  make  such  country  healthy,  the  marshes 
must  be  completely  dried  and  filled  up,  and  then 
transformed  into  cultivated  ground.  So,  again,  the 
river  valleys  in  France  only  become  unhealthy  when 
the  stream  returns  to  its  bed,  leaving  the  adjoining 
meadows  transformed  into  marshes,  which  gradually 
dry  up  and  send  forth  into  the  air  a  host  of  spores, 
produced  by  the  schizophyta  deposited  by  the  water. 
Finally,  great  excavations  of  earth  diffuse  through  the 
atmosphere  the  dormant  spores  brought  thither  by  rain, 
and  remaining  in  a  desiccated  state  in  the  soil. 

In  many  cases,  the  intervention  of  two  microbes  of 
different  kinds  have  been  assumed  to  explain  the  nature, 
and  progress  of  great  epidemics,  such  as  cholera,  yellow 
fever,  and  typhoid  fever.  This  is  termed  by  Nageli  the 
diblastic  theory  (or  that  of  two  producing  agents  of 
disease).  Thus  the  microbe  of  malaria,  or  intermittent 
fever,  which  is  not  contagious,  often  predisposes  the 
patient  to  receive  the  attacks  of  another  zymotic 
disease,  such  as  cholera  or  typhoid  fever.  The  two 
microbes  may  subsist  simultaneously  in  the  human 
frame,  and  their  joint  action  may  weaken  the  organism 
at  the  expense  of  which  they  live  and  multiply. 
Numerous  cases  might  be  cited  to  support  this  theory, 
and  the  following  examples  may  be  given : — 

"  In  the  summer  and  autumn  of  1873  the  town  of 
Spires  was  visited  by  cholera,  which  was  limited  to 


THE  MICROBES  OF  HUMAN  DISEASES.  169 

the  lower  part  of  the  town,  situated  on  the  banks  of 
the  Speyerbach.  There  was  a  hospital  for  old  men, 
situated  in  the  high  part  of  the  town,  a  quarter  which 
remained  free  from  cholera,  but  24  out  of  the  200 
pensioners  whom  the  hospital  contained  were  attacked 
by  the  disease.  Now  33  of  these  men,  the  most  able- 
bodied  among  them,  had  been  employed  to  dig  up 
some  blighted  potatoes  in  a  field  which  lay  very  low, 
almost  on  a  level  with  the  water  which  had  collected 
in  a  deserted  sand-pit.  They  had  not  drunk  of  the 
water  in  this  field,  neither  had  they  passed  through 
the  part  of  the  town  visited  by  the  epidemic  :  20  out 
of  these  33  men  had  cholera,  and  only  4  others  out  of 
all  the  inmates  of  the  hospital  contracted  the  disease" 


Observations  made  on  board  English  transports 
on  the  voyage  from  India  give  analogous  results. 
".Detachments  of  equal  number  from  two  regiments 
embarked  on  the  same  steam  transport.  A  few  days 
later,  cholera  declared  itself  and  carried  off  many 
soldiers,  all  belonging  to  one  of  the  two  regiments, 
and  coming  from  a  camp  in  which  there  was  a  violent 
outbreak  of  cholera  shortly  after  their  departure.  The 
detachment  from  the  other  regiment,  coming  from  a 
place  exempt  from  cholera,  altogether  escaped."  Here 
the  influence  of  the  locality  and  the  soil  is  evident  ;  it 
was  the  sole  and  essential  agent  of  the  disease,  since 
the  contagion  could  not  have  occurred  on  board  ship, 
in  which  the  conditions  are  generally  healthy,  neither 


170          MICROBES,  FERMENTS,   AND  MOULDS. 

by  contact  with  the  men,  nor  by  that  with  the 
clothes  and  baggage,  which  were  mixed  together. 
The  cholera  microbe  which  had  been  brought  on 
board  ship  could  only  act  on  the  detachment  mias- 
matically  predisposed  by  their  previous  residence  in 
an  unhealthy  place,  containing  the  malaria  microbe 
(Nageli). 

Miasma  and  Microbes. — This  leads  us  to  say  a  few 
words  on  the  term  miasma,  formerly  in  such  common 
use,  and  now  without  meaning.  Before  the  existence 
of  microbes  and  air-germs  was  known,  the  doubtful 
and  mysterious  principles  which  were  believed  to  be 
the  cause  of  virulent  and  contagious  diseases  were 
termed  miasmata,  and  these  miasmata  were  generally 
supposed  to  be  gases.  It  is  now  proved  that  this  cause 
resides  in  solid,  living  particles,  the  microbes  and  their 
germs:  the  term  miasma  is  less  and  less  employed, 
or  serves  to  designate  air-germs.  When,  therefore, 
Nageli  uses  the  word,  he  regards  it  as  synonymous 
with  microbes  or  air-germs. 

TI&  Question  of  Privies. — Hence  it  follows  that 
it  is  erroneous  to  apply  the  name  of  miasmata 
to  true  gases,  some  of  which  exert  an  injurious  in- 
fluence on  the  human  system.  Such  are  sulphuretted 
hydrogen  and  ammonium  sulph-hydrate  which  are 
disengaged  from  privies,  and  produce  the  disease  called 
plomb  in  the  men  employed  to  empty  them.  These 
gases  are  deleterious  to  microbes  as  well  as  to  men; 
microbes  cannot  co-exist  with  them,  which  is  perhaps 


THE  MICROBES  OF  HUMAN  DISEASES.  171 

the  reason  why  these  men  seem  to  enjoy  an  immunity 
from  most  contagious  diseases. 

People  are  too  much  disposed,  when  an  epidemic 
is  prevalent,  to  accuse  the  privies,  of  which  the 
emanations  are,  under  ordinary  circumstances,  only 
offensive  to  the  smell.  When  these  places,  as  well  as 
the  sewers,  are  properly  constructed,  they  present  no 
danger.  But  it  is  necessary  that  there  should  be 
a  sufficient  flow  of  water  in  both  to  cover  the  solid 
matter.  We  know,  in  fact,  that  if  microbes  are  present, 
they  only  become  dangerous  when  dry  enough  to  float 
in  the  air. 

In  an  epidemic  of  typhoid  fever,  for  instance,  the 
soiled  body  and  bed  linen  of  the  patient  are  much  more 
dangerous  than  the  privies,  in  which,  however,  there 
is  a  much  larger  number  of  microbes.  The  linen, 
therefore,  as  well  as  the  contaminated  rooms  and 
furniture,  should  be  immediately  disinfected  in  the 
mode  prescribed  by  sanitary  authorities. 

The  system  of  directing  everything  to  the  sewer, 
which  is  now  universally  applied  to  large  towns,  and 
which  has  encountered  much  opposition,  is  certainly 
excellent  when  properly  understood  and  applied.  The 
cesspools,  as  well  as  the  cemeteries,  ought  to  be  as 
remote  as  possible  from  the  houses  of  the  living.  It 
is  as  much  opposed  to  public  health  to  retain  cesspools 
which  are  gradually  filled  in  the  course  of  years,  in 
the  midst  of  a  town,  as  to  have  intramural  cemeteries. 
Everything  should  be  carried  off  by  the  sewer,  pro- 


172  MICROBES,  FERMENTS,   AND  MOULDS. 

vided  there  is  a  sufficient  flow  of  water  to  take  all 
solid  matters  with  it  and  completely  cover  them. 
These  are  deposited  in  places  assigned  for  them,  which 
must  necessarily  be  very  remote  from  thickly  populated 
places.  When  these  matters  are  then  spread  over 
a  large  surface  to  dry  in  the  air,  the  oxygen  becomes, 
as  Pasteur  has  said,  the  great  purifier  of  microbes. 

In  Paris,  some  of  the  sewage  water  of  the  great 
main  sewer  is  diverted  on  to  the  peninsula  of  Genne- 
villiers,  and  it  is  then  directed  into  gutters  to  serve  as 
a  manure  for  market  gardens.  After  filtering  through 
the  cultivated  plots,  the  water  flows  off  in  a  limpid 
stream. 

Cornilleau,  whose  medical  practice  is  at  Genne- 
villiers,  has  recently  issued  a  report,  showing  plainly 
that  the  sewage  is  but  a  slight  source  of  danger  to 
the  inhabitants  of  the  peninsula.  During  the  serious 
outbreak  of  typhoid  fever  which  occurred  in  Paris  in 
1882,  there  were  only  two  typhoid  cases  in  the  whole 
commune,  and  these  cases  were  imported  from  Paris. 


II.  MICROBES  OF  THE  MOUTH  AND  DIGESTIVE  CANAL 
IN  A  HEALTHY  MAN. 

Since  there  is  a  profusion  of  microbes  in  the  air, 
we  can  easily  understand  why  they  should  be  found 
in  the  human  mouth,  and  hence  in  all  parts  of  the 
digestive  canal.  They  are  for  the  most  part  harmless, 


THE  MICROBES  OF  HUMAN  DISEASES.  173 

as  long  as  the  epidermis  of  the  mucous  membrane 
covering  the  intestinal  canal  is  healthy.  Pasteur  has 
shown  that  they  are  not  found  in  the  blood  of  a 
healthy  man,  but  that  the  slightest  lesion  of  the 
mucous  membrane  suffices  to  introduce  them  into  the 
circulation.*  This  fact  was  proved  by  experiments 
made  at  Pouilly-le-Fort  on  sheep,  inoculated  with  the 
anthrax  microbe  by  means  of  their  food.  The  mortality 
among  these  animals  was  notably  increased  when 


FVs.  77,  78. — Spirochrrtr  hurrah's,  and  S.  plicatit>'s.  b  (mixed  with  Vibrio  rugttla, 
a),  microbes  in  mouth  of  a  healthy  mail. 

thistles,  bearded  grain,  or  sharp-edged  leaves  were 
mixed  with  their  food,  so  as  to  cause  little  wounds  in 
their  mouths,  each  of  which  served  as  an  entrance  for 
microbes.  As  long  as  the  microbes  are  few  in  number, 
they  perish  quickly  in  the  blood;  but  when  the 
number  is  considerable,  the  organism  has  not  the  power 
to  destroy  them ;  they  soon  compete  with  the  corpuscles 
of  the  blood,  and  the  most  serious  diseases  ensue. 

Miquel  estimates  the  number  of  spores  introduced 
into  the  human  system  by  respiration,  when  the  health 

*  This  is  not  the  case  with  fishes.    Richet  and  Ollivier  have  shown 
that  microbes  are  normally  found  in   the  blood  of  sea-fish,  without 
heir  health. 


174          MICEOBES,   FERMENTS,   AND  MOULDS. 

is  perfectly  sound,  at  300,000  a  day,  and  100,000,000 
a  year.  It  is  evident  that  these  germs,  always 
present,  may  easily  become  the  source  of  diseases,  of 
which  thrush  in  the  mouth  of  infants,  and  of  sick  and 
dying  adults,  is  one  of  the  least  alarming. 

Steinberg,   surgeon   of  the   United   States   army, 
1880,  writes:  "When  I  was  occupied  in  the  micro- 


Fig.  79. — Vibrio  rugula  (Warming)  in  different  stages  of  development :  b,  c,f,  indi- 
viduals with  vibratile  cilia  (jlagellum) ;  /',  ciliated  spores.  Found  in  the  human 
mouth  and  intestines. 

scopic  examination  of  foul  river  water  at  'New  Orleans, 
I  used  to  find  in  my  own  mouth  almost  all  the 
organisms  which  were  present  in  the  putrefying  liquid 
I  was  examining — Bacterium  termo,  Bacillus  subtilis 
(Fig.  80),  Spirillum  undulatum,a,nd  a  variety  of  minute 
spherical  forms  and  of  rods,  difficult  to  classify  except 
under  the  generic  names  of  Micrococci  and  Bacteria. 
Another  organism  which  I  have  often  found  in  healthy 
human  saliva  is  a  species  of  Sarcina,  perhaps  identical 
with  8.  ventriculi" 

But   the  organism  most  commonly  found  in  the 
human  mouth,  which  attracts  attention  from  its  large 


THE  MICROBES  OF  HUMAN  DISEASES. 


175 


size  and  its  abundance,  is  Leptothrix  buccalis.  It  is 
never  absent  from  the  rough  surface  of  the  tongue 
or  the  interstices  of  the  teeth,  and  even  those  persons 
who  make  a  frequent  use  of  the  tooth-brush  are  not 
exempt  from  it.  In  the  latter  case,  however,  it  only 
appears  in  the  form  of  short,  scattered  rods ;  while  in 


G 


Fig.  80.— Bacterium  (Hacillus)  tubtilis  (%>pf\  in  different  stages :  A.  ciliated  rods  ; 
E,  F,  spores ;  G,  Zoogloea.  In  inluMons  of  buy,  and  in  the  human  muuth  (much 
magnified). 

other  cases,  the  tufted  stems  of  its  vigorous  growth 
abound  in  the  saliva,  and  are  often  established  on  the 
epithelial  cells,  whence  they  may  be  detached  by  friction. 
Sternberg  compares  the  human  mouth  to  a  culture 
apparatus,  in  which  the  germs  of  microbes  find  an  even 
temperature  and  the  moisture  necessary  for  their 
development  naturally  provided  for  them — conditions 
which  can  only  be  artificially  produced  in  the 
laboratory. 


176  MICROBES,   FERMENTS,   AND  MOULDS. 


III.  THE  VIRULENT  MICROBE  OF  HEALTHY  HUMAN 
SALIVA. 

Pasteur  and  Vulpian  in  France,  and  Sternberg  in 
America,  discovered  almost  simultaneously  that  the 
human  saliva  may,  under  conditions  with  which  we 
are  still  imperfectly  acquainted,  beco^me  virulent,  and 
that  this  virulence  is  due  to  the  action  of  a  Micrococcus, 
normally  present  in  the  saliva,  a  microbe  quite  distinct 
from  that  of  rabies,  of  which  we  have  already  spoken. 

It  is  only  known  that  this  micrococcus  is  very 
common  in  the  saliva  of  a  healthy  man,  and  that  in 
some  individuals  the  saliva  is  exceptionally  virulent. 
When  injected  under  the  skin  of  healthy  rabbits,  it 
produces  grave  affections,  often  resulting  in  the  animal's 
death.  These  affections  are  due  to  the  presence  of 
the  micrococcus,  since  the  saliva  becomes  harmless  as 
soon  as  these  organisms  are  removed  from  it. 

Sternberg  informs  us  that  his  own  saliva  is 
among  those  which  possess  this  curious  and  alarming 
property.  He  regards  the  more  abundant  nutriment 
which  this  microbe  finds  in  the  mouths  of  some 
persons  as  the  cause  of  this  virulence,  since  thus  its 
development  is  more  energetic.  "  In  my  own  case," 
he  writes,  "there  is  a  very  abundant  secretion  of 
saliva.  .  .  .  My  culture  experiments  show  that  this 
micrococcus  multiplies  very  rapidly,  and  in  virtue  of 
this  faculty  it  has  for  a  certain  time  the  advantage 


THE  MICROBES  OF  HUMAN  DISEASES.  177 

over  Bacterium  termo,  which  appears  to  be  fatal  to 
the  former  when  piesent  in  any  number.  ...  In 
my  culture  flasks,  a  small  drop  of  blood  from  an  in- 
fected rabbit  gave  birth  within  a  few  hours  to  such 
a  number  of  microbes  that  the  liquid  contained  in  the 
flask  was  completely  filled  with  them,  and  it  was 
deprived  of  the  nutriment  necessary  for  any  further 
development." 

The  exceptional  virulence  of  this  microbe  must 
therefore  be  ascribed  to  its  vital  and  reproductive 
energy,  and  to  the  rapidity  with  which  it  multiplies ; 
at  any  rate,  until  we  know  more  on  the  subject 


IV.  THE  MICROBES  OF  DENTAL  CARIES. 

Miller's  recent  researches  (1884)  tend  to  show  that 
dental  caries  is  chiefly  due  to  the  development  of  one 
or  more  species  of  bacteria.  The  presence  of  acids 
introduced  into  the  mouth,  or  developed  by  certain 
diseases  (ulcers,  thrush,  etc.)  which  are  themselves 
produced  by  microbes,  appears  to  be  the  predisposing 
cause  of  this  affection.  These  acids  begin  by  softening 
the  dentine,  deprived  at  some  point  of  its  superficial 
coating  of  enamel,  and  through  this  the  bacteria  enter. 
Saliva  can  be  rendered  experimentally  acid  by  mixing 
it  for  four  hours,  at  a  temperature  of  20°,  with  sugar 
and  starch  (Cornil).  Hence  the  injuriousness  of  sugar- 
plums and  other  sweetmeats,  long  and  correctly 
9 


178          MICROBES,  FERMENTS,   AND  MOULDS. 


Fig.  81.— Bacterium  of  dental 
Caries  in  the  dentine  tu- 
bules: a,  artificial  caries; 
b,  spontaneous  caries. 


supposed  to  be  the  cause  of  the  early  decay  of  teeth, 
especially  in  children  who  eat  them  in  excess. 

The  microbe  which  Miller  has 
found  to  be  most  common  in  de- 
cayed teeth  is  very  polymorphic. 
Microccocus,  bacterium,  chains  and 
filaments,  are  only  different  phases 
of  the  same  plant,  which  also  pro- 
duces acid  fermentation  in  the 
mouth,  and  the  formation  of  lactic 
acid.  Within  the  dentine  tubules, 
a  section  examined  under  the 
microscope  shows  all  the  inter- 
mediate stages  between  the  isolated 
micrococcus  and  the  filaments 
(Figs.  81,  82).  Miller  succeeded 
in  producing  this  disease  in  sound  teeth  artificially. 


I 


0 

0 

0 
0 

°0 


Fig.  82.— Bacterium  of  dental  caries :  a,  6,  different  forms  obtained  in  gelatine 
culture. 

According  to  his  experiments,  the  best  dentifrice  for 


THE  MICROBES  OF  HUMAN  DISEASES.  179 

the  destruction  of  microbes  is  a  solution  of  corrosive 
sublimate  (mercuric  chloride),  one  part  in  1000,  which 
can  be  further  diluted  by  four  parts  of  pure  water. 


V.  MICROBES  OF  INTERMITTENT  OR  MALARIOUS 
FEVERS. 

We  say  microbes  in  the  plural,  since  it  is  almost 
certain  that  the  different  types  of  intermittent  fever, 
tertian,  quartan  fever,  etc.,  are  produced  by  different 
microbes ;  moreover,  it  is  probable  that  these  microbes 
vary  with  the  locality.  That  of  intermittent  fever 
in  France  is  probably  not  the  same  as  that  of  the 
malaria,  or  fever  of  the  Pontine  marshes  in  Italy  ; 
and  the  African  fevers,  again,  are  probably  produced 
by  a  different  organism. 

Intermittent  fevers  are  the  first  internal  diseases 
of  which  the  vegetable  parasitic  nature  was  sus- 
pected. Before  that  time  we  were  only  acquainted 
with  the  parasites  of  the  skin,  and  with  the  entozoaria 
and  epizoaria  (intestinal  worms,  lice,  acari,  etc.),  which 
are  animals.  In  18G9,  Dr.  Salisbury,  of  Cleveland,  U.S., 
entered  on  researches  which  led  him  to  the  con- 
clusion that  intermittent  fever  in  the  marshy  valleys 
of  the  Ohio  and  the  Mississippi  must  be  ascribed  to 
the  presence  in  the  system  of  a  filamentous  alga 
which  approximates  to  the  genus  Palmetto,.  The 
spores  of  this  alga  are  constantly  found  in  the  saliva 


180          MICROBES,   FERMENTS,   AND   MOULDS. 

of  the  subjects  of  intermittent  fever.  By  exposure 
during  the  night  of  little  glass  plates  in  marshy 
meadows,  Salisbury  was  able  to  collect  similar  spores, 
which  settled  on  the  lower  surface  of  the  glass,  and 
were  found  floating  in  the  drops  of  condensed  dew.* 
On  passing  through  these  marshes  in  the  evening, 
there  was  a  peculiar  sense  of  dryness  in  the  throat, 
and  expectoration  revealed  the  presence  of  spores  of 
Palmella.  Finally,  earth  taken  from  these  marshes 
was  found  to  be  full  of  the  same  organisms. 

When  the  marsh  begins  to  dry  up,  the  spores  are 
produced  in  abundance,  and  intermittent  fevers  occur. 
Salisbury  writes  that  "  in  18H2,  the  weather  was  very 
wet  until  about  the  1st  of  July ;  but  that  during 
July,  August,  and  September,  there  was  hardly  a  drop 
of  rain.  The  springs  and  water-courses  were  nearly 
dried  up,  the  marshes  and  wet  grounds  also  became 
dry,  vegetation  was  almost  completely  arrested,  and 
the  whole  country  presented  an  arid  appearance. 
Shortly  after  the  drought  began,  intermittent  fever 
made  its  appearance  in  all  the  unhealthy  districts,  and 
spread  so  rapidly  during  the  months  of  July  and 
August,  that  it  attacked  almost  every  family  living 
on  marshy  ground. 

"  A  low,  peaty  meadow  extends  along  the  canal 

*  We  must  repeat  what  has  been  said  before^,  that  the  presence 
of  these  spores  in  the  air  is  quite  independent  of  that  of  the  vapour 
which  constitutes  dew ;  in  other  words,  the  vapour  does  not  transport 
these  spores,  which  must,  on  the  contrary,  be  perfectly  dry  before  they 
can  float  in  the  air  and  settle  on  any  damp  object. 


THE  MICROBES  OF  HUMAN  DISEASES.  181 

to  the  south-east  of  the  to\*n  of  Lancaster,  and  the 
neighbouring  valleys  are  low  and  damp.  The  third 
quarter  of  the  town,  touching  on  this  meadow,  and 
all  that  part  which  is  not  raised  from  35  to  40  feet 
above  the  level  of  the  meadow,  have  always  been 
districts  in  which  attacks  of  intermittent  fever  are 
prevalent.  Those  who  live  near  the  marsh  are  liable 
to  annual  attacks  of  fever  from  May  to  November. 
In  August  and  September  these  attacks  are  generally 
the  most  severe." 

We  said  that  moisture  does  not  favour  the  trans- 
port of  microbes  and  their  spores  through  the  air, 
but  the  remark  does  not  apply  to  fogs,  in  which 
numerous  spores  are  found.  We  know  that  fogs  are 
formed  of  minute  globules  of  water,  which  float  in 
the  atmosphere,  and  of  which  the  vapour  of  our 
breath,  only  visible  in  cold  weather,  can  give  us  an 
idea.  These  globules  of  water  float  in  the  air  just  as 
spores  and  all  kinds  of  dust  do,  without  wetting 
the  spores  or  running  together,  since  as  soon  as  this 
occurs,  the  fog  ceases  to  be ;  it  is  condensed,  and  falls 
in  the  form  of  more  or  less  fine  rain.  Salisbury  has 
ascertained  that  there  is  a  certain  connection  between 
fogs  and  intermittent  fevers,  and  this  explains  why 
people  are  more  apt  to  contract  fever  in  the  morning 
and  evening,  at  which  times  there  is  in  summer  always 
a  fog  floating  to  a  varying  height  above  marshy  places. 
In  a  farm  near  Lancaster,  the  firmer  and  his  wife,  who 
slept  on  the  first  floor,  were  attacked  by  tertian  fever, 


182          MICKOBES,  FERMENTS,   AND  MOULDS. 

while  their  seven  children,  who  slept  on  the  second 
floor,  escaped.  Salisbury  ascertained  that  there  was 
a  fog  every  morning,  rising  from  a  reservoir  which 
had  been  recently  made.  This  fog  reached  the  house 
and  rose  above  the  first  floor,  but  not  as  high  as  the 
windows  of  the  second  floor,  and  penetrated  into  the 
parents'  bed-chamber  through  the  open  window.  This 
vapour  had  the  same  smell  as  the  marsh,  which  was 
covered  with  fever  algae  (Palmella  febrilis),  and  pro- 
duced the  same  feverish  dryness  in  the  throat  and 
pharynx.  The  vapour  dispersed  soon  after  sunrise, 
and  before  the  children  had  left  their  chamber. 

Salisbury  likewise  ascertained  the  polymorphism 
of  Palmella  febrilis,  a  polymorphism  which  is  con- 
firmed by  the  recent  observations  of  the  skilful 
naturalist  Zopf,  and  this  fact  explains  the  mode  in 
which  an  aquatic  alga  can  live  in  the  human  blood, 
in  the  form  of  Bacillus  or  Spirillum. 

Still  more  recently  (1879),  marsh  fever,  or  malaria, 
which  is  so  common  in  Sicily  and  in  the  Roman 
Campagna,  have  been  studied  from  the  same  point 
of  view  by  Crudeli,  Cuboni,  Cecci,  and  others,  who 
ascribe  the  disease  to  a  vegetable  parasite  which  they 
call  Bacillus  malarias.  This  bacillus  is  abundantly 
found  in  the  blood  of  patients  during  the  period  of 
attack,  while  during  the  period  of  acme  which  ter- 
minates each  attack  only  spores  are  found.  The  same 
microscopic  organism  is  found  in  all  the  malarious 
districts  of  the  Eoman  Campagna,  and  it  can  be 


THE  MICROBES  OF  HUMAN  DISEASES.  183 

produced  in  artificial  cultures.  It  is  not  found  in  the 
healthy  parts  of  Lombardy.  In  the  strata  of  air 
which  float  above  malarious  ground  in  summer,  this 
microbe  is  so  common  that  it  is  found  in  abundance 
in  the  sweat  of  the  forehead  and 

|  *  /  ^/^  \        hands  (Fig>  83)' 

This    organism   is  not   only 

capable  of  cultivation,  but  rabbits 
and  dogs  can  be  inoculated  with 
bacillus  it*  so  as  to  produce  marsh  fever 
in  them  *  The  lesions  which 
are  observed  in  an  autopsy  are  the  same  as  those  in 
man,  showing  that  the  site  preferred  by  the  microbe  is 
the  spleen  and  the  marrow  of  the  bones. 

The  fact  that  the  bacillus  and  its  spores  are  suc- 
cessively found  in  the  blood  explains  the  intermittent 
type  of  the  disease,  tertian,  quartan,  etc.,  according  to 
the  variety  of  marsh  fever.  According  to  its  variety, 
and  perhaps  to  the  species  of  Schizophytum,  the  com- 
plete evolution  of  the  plant  sometimes  demands  48, 
sometimes  72  hours,  and  the  access  of  fever  always 
corresponds  with  the  period  of  greatest  activity  in 
the  bacillus — that  which  precedes  the  emission  of 
spores. 

Two    military   surgeons,  Laveran    and    Richard, 

*  It  is  generally  believed  in  France  that  animals,  and  especially 
herbivora,  cannot  contract  intermittent  fever.  This  opinion  is  erro- 
neous. It  is  known  that  in  Italy  cattle  contract  this  fever  when  they 
are  not  acclimatized  to  marshy  districts,  aud  that  they  are  cured  by 
sulphate  of  quiuiue. 


184  MICROBES,  FERMENTS,   AND  MOULDS. 

have  also  observed  the  parasitic  nature  of  intermittent 
fever  in  Algeria.  The  organism  which  they  have 
constantly  found  in  the  blood  of  those  affected  by 
marsh  fever  presents  several  different  aspects,  but 
appears  especially  to  attack  the  red  corpuscle  of  the 


Fig.  84. — Parasite  of  intermittent  fever  (La veran):  A,  normal  hfematin;  B,  B,  corpuscle 
No.  1;  C,  corpuscle  No.  2,  motionless;  D,  corpuscle  No.  2,  containing  mobile 
pigmented  grains  ;  E,  corpuscle  No.  2,  provided  with  mobile  filaments ;  G,  detached 
mobile  filament ;  H,  H,  corpuscle  No.  3 ;  I,  K,  corpuscle  No.  2,  of  small  size, 
red  and  agglomerated ;  L,  L,  haematins  to  which  the  small  corpuscles  No.  2  are 
attached ;  M,  pigmented  leucocytes,  their  nuclei  made  visible  by  carmine. 


blood,  in  which,  according   to  Laveran's   expression, 
"  it  is  encysted  like  a  weevil  in  a  grain  of  wheat." 


THE  MICROBES  OF  HUMAN  DISEASES.  185 

This  observer  thinks  that  it  approximates  to  the 
algie  of  the  genus  Oscillaria  *  (Fig.  84). 

The  different  forms  taken  by  this  organism  are 
only  the  successive  phases  of  its  development,  and 
have  not  yet  been  observed  by  a  competent  botanist, 
who  alone  can  indicate  precisely  their  true  nature. 
At  a  certain  period  of  its  existence  the  parasite 
attaches  itself  to  the  red  corpuscle  of  the  blood,  and 
is  nourished  at  its  expense.  The  corpuscle  turns  pale, 
loses  its  colouring  matter,  and  disappears,  leaving  as 
residue  a  small  grain  of  pigment,  representing  the 
haemoglobin  absorbed  by  the  parasite.  Two  or  three 
mobile  filaments  arise  from  the  encysted  parasite, 
which  resemble  vibrios,  and  move  rapidly  in  the  blood 
as  soon  as  they  become  detached.  Laveran  states  that 
he  has  found  the  same  organism  in  malaria  patients 
at  Rome;  and  Richard  found  them  in  the  blood  of 
a  sailor  just  returned  from  China,  who  was  suffering 
from  intermittent  fever.  The  use  of  the  microscope 
permits  an  accurate  diagnosis  of  this  disease. 

The  spherical  bodies,  or  the  microbe  in  its  encysted 
form,  announce  that  the  attack  is  imminent,  and  no 
time  should  be  lost  in  administering  sulphate  of 
quinine.  Richard  writes  that  "  the  multiplication  of 
these  bodies  must  be  extremely  rapid.  For  instance, 
in  tertian  fever  they  are  not  found  in  the  intervals 
of  the  attacks  (apyrexia).  As  the  attack  approaches, 

*  litoue    Sckntijl'iue,  April   20,  1SS2,  p.  527;    Juuuar      27,  1883, 


186          MICKOBES,  FEEMENTS,  AND  MOULDS. 

they  appear  in  increasing  numbers,  and  their  maximum 
corresponds  with  the  beginning  of  the  rise  in  tempera- 
ture; from  that  moment  they  begin  to  perish,  since 
the  heat  of  fever  is  fatal  to  them,  and  completely 
checks  their  development.  This  explains  the  inter- 
mittent character  of  the  disease.  They  produce  fever, 
the  fever  kills  them  and  then  subsides ;  when  apyrexia 
occurs  they  multiply  again,  excite  fever,  and  so  on." 
Thus  there  is  a  successive  series  of  auto-infection  by 
the  parasite  itself,  unless  its  development  is  arrested 
by  sulphate  of  quinine.  "The  parasites  of  typhus 
and  typhoid  fever  are  not  affected  by  a  temperature 
of  40°,  and  even  of  42°,  and  hence  the  continuous 
character  of  these  fevers." 

Cornil  has,  with  some  justice,  criticized  Laveran's 
description  and  illustrations  of  the  parasite  of  marsh 
fever.  It  is  difficult  to  recognize  in  it  an  organism 
really  belonging  to  the  animal  or  vegetable  kingdom. 
The  form  of  the  filaments  which,  as  he  asserts,  issue 
from  the  so-called  encysted  bodies,  resemble  those 
which  Hoffmann  has  seen  and  drawn  in  blood  in  its 
normal  state,  and  also  in  various  diseases,  and  are 
probably  only  expansions  of  extravasated  protoplasm 
in  the  red  corpuscles  at  a  temperature  of  40°.  The 
encysted  bodies  are  also,  according  to  all  appearance, 
only  blood-corpuscles,  more  or  less  affected  by  disease. 

There  only  remain  the  pigmented,  encysted  granules 
in  the  red  and  colourless  corpuscles,  granules  which 
have  been  observed  by  others,  and  especially  by 


THE  MICROBES  OF  HUMAN  DISEASES.  187 

Marchiafava  and  Celli.  But  experiments  undertaken 
to  show  that  these  granules  are  microbes  have  as  yet 
afforded  no  certain  results. 

In  short,  Cornil  remarks :  "  Since  bacteria  are 
found  neither  in  the  internal  organs  nor  in  the  blood 
of  those  who  die  of  intermittent  fever,  we  are  tempted 
to  suppose  that  the  virulent  agent  resides  in  the  sur- 
face of  the  mucous  membrane — for  example,  in  that  of 
the  digestive  canal ;  and  that  the  chemical  poisons  pro- 
duced under  the  influence  of  these  micro-organisms 
penetrate  thence  into  the  blood.  They  then  act  on 
the  red  corpuscles  of  the  blood." 

Finally,  we  must  remember  that  many  continuous 
fevers,  especially  those  of  hot  countries,  seem  to  be 
complicated  by  the  presence  of  two  parasitic  elements, 
as  we  have  said  in  describing  Nageli's  diblastic  theory. 
To  the  marsh  microbe,  which  comes  from  the  soil, 
another  is  added,  of  which  the  immediate  origin  is 
due  either  to  direct  contagion,  or  to  some  other  telluric 
or  atmospheric  local  influence. 


VI.  RECURRENT  FEVER  AND  YELLOW  FEVER. 

We  place  these  two  diseases  together,  simply 
because  they  have  rarely  been  observed  in  France. 
Recurrent  fever,  or  relapsing  typhus,  is  a  disease 
which  has  been  observed  in  Germany,  Russia,  Ireland, 
and  India,  in  which  latter  country  it  is  called  jungle 


188          MICROBES,  FERMENTS,  AND  MOULDS. 

fever.  In  all  these  countries  poverty,  scarcity,  and 
famine  appear  to  be  the  predisposing  causes.  In 
this  case,  the  presence  of  microbes  in  the  human 
blood  has  been  established  in  the  clearest  and  most 
incontestable  way.  This  discovery  was  made  by 
Virchow  and  Obermeier  in  1868,  but  nothing  was 
published  on  the  subject  until  1873. 

The  symptoms  of  the  disease  are  very  like  those 
of  typhoid  fever.  The  microbe,  which  may  always 
be  found  in  the  blood,  and  which  characterizes  the 
disease,  is  a  Spirillum  or  Bpvrochafa  (S.  Olermeieri) ; 
that  is,  a  filamentous  organism,  twisted  into  several 
spirals,  and  animated  by  very  lively  movements  (Fig. 
51,  m,  0).  These  spirilla  may  be  seen  moving  in 
thousands  among  the  blood-corpuscles,  when  these  are 
placed  under  the  objective  of  the  microscope. 

The  difficulties  experienced  by  the  original 
observers  in  their  attempts  to  inoculate  man  or 
animals  with  the  disease,  and  the  fact  that  in  some 
cases  the  microbes  appear  to  be  absent  from  the 
blood  of  affected  persons,  have  thrown  some  doubt 
on  the  relation  between  the  disease  and  its  microbe. 
This  is  because  the  conditions  of  the  existence  of 
this  plant  in  the  system  were  not  sufficiently  con- 
sidered. Albrecht  has  recently  shown  (1880)  that 
blood  which  apparently  contains  no  spirilla  will,  if 
kept  in  a  culture-flask  for  some  days,  protected  from 
air-germs,  become  full  of  these  organisms  at  the  end 
of  that  time,  a  proof  of  the  pre -existence  of  the  spores 


THE   MICROBES   OF   HUMAN    DISEASES.          189 

The  same  observer  was  able  to  point  out  the  spores, 
which  are  only  visible  under  a  magnifying  power 
of  1000  diameters,  and  which  succeed  to  the  spirilla 
during  the  remittent  period.  Moreover,  a  monkey  was 
successfully  inoculated  with  the  disease  at  Bombay, 
and  after  the  lapse  of  five  days  spirilla  were  found 
in  the  animal's  blood. 

Yellow  fever  has  not  yet  been  sufficiently  studied 
in  the  countries  in  which  it  prevails,  but  there  can 
be  no  doubt  that  it  is  likewise  produced  by  a  special 
schizophytum.  Originating,  as  it  appears,  in  North 
America,  probably  in  the  delta  of  the  Mississippi,  this 
disease  has  been  spread  by  maritime  commerce  over 
the  whole  intertropical  zone  of  the  globe.  The  centres 
of  infection  are  always  on  the  sea-board,  at  the  mouths 
of  great  rivers,  from  which  we  conclude  that  its  special 
microbe  is  found  in  its  free  state  in  the  brackish 
marshes  formed  at  river-mouths. 

The  medical  men  of  Rio  de  Janeiro,  and  particu- 
larly Freire,  have  lately  described  and  published  illus- 
trations of  microbes  said  to  have  been  observed  by 
them  in  the  faeces  of  patients  attacked  by  yellow 
fever.  But  their  drawings  are  for  the  most  part 
fanciful,  and  betray  great  inexperience  in  the  methods 
of  research  and  in  microscopic  examinations;  for 
instance,  the  air-bubbles,  unskilfully  interposed  in 
the  preparations  which  their  author  thought  worthy 
of  photographic  reproduction,  figure  as  microbes. 
Thanks  to  the  accuracy  of  photography,  which  leaves 


190          MICROBES,  FERMENTS,  AND  MOULDS. 

no  scope  for  the  fancy  of  a  draughtsman,  there  can 
be  no  doubt  as  to  the  gross  error  committed  by  the 
observer. 

As  for  Freire's  attempts  at  vaccination,  his  own 
statistics  are  far  from  being  favourable  to  his  method ; 
in  fact,  they  prove  that  vaccination  increased  the 
rate  of  deaths  in  the  proportion  of  19  per  100. 

Much  more  scientific  researches  were  undertaken 


Fig.  85.— Section  of  Kidney  in  yellow  fever  (Babes),  showing  a  capillary  vessel,  c, 
filled  with  chaplets  of  micrococci. 

by  Cornil  in  Paris,  on  some  anatomical  preparations, 
preserved  in  alcohol,  which  were  sent  from  Brazil. 
He  found  in  the  liver  and  kidney  of  the  victims  of 
yellow  fever,  chaplets  of  micrococci  or  bacteria  (Fig. 
85),  only  visible  under  a  very  strong  magnifying 


THE  MICROBES  OF  HUMAN  DISEASES.  191 

power  (more  than  1000  diameters).  But  they  are  not 
invariably  present,  and  it  is  consequently  uncertain 
whether  they  are  the  cause  of  the  disease.  From  its 
symptoms  and  lesions,  there  is  reason  to  think  that 
the  parasite  or  parasites — for  there  may  be  several, 
according  to  Nageli's  theory — have  their  seat  in  the 
digestive  canal.  New  and  sustained  researches,  carried 
on  in  countries  where  yellow  fever  prevails,  and  more 
methodically  conducted,  are  necessaiy  to  elucidate  this 
question. 


VII.  TYPHOID  AND  TYPHUS  FEVERS. 

These  two  diseases  may  be  taken  together,  since 
in  both  the  digestive  canal  is  the  part  chiefly  affected. 

Here  crowding,  the  aggregation  of  men  and  the 
human  miasmata  resulting  from  it,  play  the  chief 
part,  admitting,  as  we  have  already  said,  that  miasma 
means  microbe.  We  need  not,  therefore,  deny  the  in- 
fluence of  predisposing  conditions,  or  what  is  called 
receptivity  for  the  disease.  These  unfavourable  con- 
ditions are:  physical  exhaustion,  bad  food,  youth, 
mental  emotion — all  which  conditions  are  allied  with 
human  miasmata,  the  result  of  crowding  in  barracks, 
where  typhoid  fever  prevails;  in  camps,  which  are 
more  subject  to  typhus;  and  in  the  badly  built 
houses  of  our  large  cities. 

la  few  diseases  is  the  influence  of  anti-hygienic 


192          MICROBES,  FEEMENTS,   AND  MOULDS. 

conditions  more  apparent.  Want  of  air  and  cleanli- 
ness is  one  of  the  principal  factors  of  these  cruel 
epidemics.  In  the  confined  lodgings  of  the  artisans 
of  large  cities,  the  dead,  the  sick,  and  the  healthy 
man  may  be  found  sharing  the  same  room  and  even 
the  same  bed;  linen  impregnated  with  typhoid  ex- 
cretions may  remain  for  days  in  the  same  chamber. 
The  walls  and  floors  of  our  barracks,  too  rarely  cleansed, 
disinfected,  or  whitewashed,  harbour  myriads  of  mi- 
crobes; and  the  water  of  adjoining  wells  likewise  con- 
tains them  in  great  numbers. 

Nor  can  it  be  said  that  hygienic  conditions  are 
more  carefully  observed  in  the  rural  habitations  of 
villages  and  detached  farms.  The  peasant  is  as 
ignorant  of  the  laws  of  health  and  cleanliness  as  the 
artisan;  the  neglect  of  the  builder,  often  a  mere 
mason,  of  the  landlord  and  the  tenant,  is  still  more 
striking  in  country  districts.  For  this  reason  epi- 
demics are  generally  more  fatal  in  the  country  than 
in  towns ;  but  they  are  less  frequent,  of  shorter  dura- 
tion, and  more  easily  localized  in  a  village  or  detached 
farm,  since  in  this  case  there  is  a  large  supply  of 
oxygen,  which  is  the  great  destroyer  of  microbes. 

With  respect  to  typhoid  fever,  one  of  the  most 
common  diseases  in  this  country,  the  lesions  by  which 
it  is  always  characterized  show  that  the  microbe  pro- 
ducing it  is  chiefly  found  in  the  mucous  membrane  of 
the  intestines,  in  Peyer's  glands,  and  in  the  isolated 
follicles  which  cover  this  membrane,  and  which  aro 


THE  MICROBES  OF  HUMAN  DISEASES.  1(J3 

always  hypertrophied  and  softened  in  typhoid  patients. 
The  round  red  spots  which  may  be  observed  upon  the 
skin  are  distinctive  marks  of  the  affection  of  the  diges- 
tive canal,  and  it  has  occurred  to  Bouchardat  that  if,  as 
he  supposes,  these  spots  contain  the  same  microbe  as  that 
of  the  intestines,  it  might  be  cultivated  and  attenuated 
into  a  true  vaccine. 

The  presence  of  special  microbes  in  typhoid  fever 
was  first  observed  by  Recklinghausen  in  1871,  but  the 
exact  description  of  the  typhoid  bacillus  has  been  only 
recently  given  by  Eberth  and  Klebs. 

Eberth  has  observed  this  bacillus  in  the  spleen, 
the  lymphatic  glands,  and  the  intestines,  making 
use  of  special  staining  processes.  It  appears  in  the 
form  of  short  rods  with  rounded  extremities,  in  the 
tubular  glands  and  round  the  bottom  of  these  glands, 
which  cover  the  mucous  membrane  of  the  intestine. 
They  are  numerous  when  the  ulceration  of  Peyer's 
glands  begins;  afterwards  they  become  fewer,  and 
are  succeeded  by  other  microbes.  From  the  position 
of  the  bacteria  in  a  section  of  the  mucous  membrane, 
it  may  be  seen  that  they  penetrate  through  its  surface, 
and  fasten  on  the  ulcerated  and  mortified  tissue 
(Cornil). 

Blood  taken  from  living  patients  often  displays 
bacilli  amid  the  red  corpuscles  (Fig.  86).  The  spleen, 
which  is  always  hypertrophied,  contains  the  same 
bacillus,  which  is  also  found  in  the  liver,  and  some- 
times in  the  kidneys  and  urine. 


194          MICROBES,  FERMENTS,  AND  MOULDS. 

Many  other  bacteria  appear  in  the  intestines  when 
the  disease  is  approaching  its  end,  but  the  bacillus  in 
question  is  the  only  one  found  in  the  blood  and 
internal  organs,  so  that  it  is  really  characteristic  of 
the  disease. 

Gaffky,  a  German  micrographist,  and  a  pupil  of 
Koch,  has  succeeded  in  the  artificial  culture  of  this 
microbe,  taking  it  from  the  spleen  of  persons  who  died 
of  typhoid  fever.  It  is  actively  developed  on  gelatine 
and  potatoes,  becomes  very  lively  and  produces  endo- 


Fig.  86— Bacilli  of  typhoid  fever  (x  1500  diam.):  three  red  corpuscles  may  be 
observed  in  the  same  preparation. 

genous  spores  at  a  temperature  of  38°.  But  the  inocu- 
lation of  animals  with  the  disease  has  hitherto  been 
unsuccessful,  at  least  so  as  to  reproduce  in  them  an 
affection  of  the  intestines,  really  resembling  that  of 
Peyer's  glands  in  man. 

The  horse  is  the  only  animal  affected  by  a  similar 
disease,  which  has  also  been  called  typhoid  fever.  In 
1881,  the  horses  of  the  Paris  Omnibus  Company  were 
decimated  by  an  epidemic  of  this  nature.  But  the 
Jesion  of  Peyer's  glands  cannot  be  compared  with  that 
which  occurs  in  the  same  glands  in  man,  and  no 
special  microbe  has  yet  been  discovered. 


THE  MICROBES  OF  HUMAN  DISEASES.  195 

The  presence  of  the  bacillus  of  typhoid  fever  in 
the  air  or  in  water  has  not  yet  been  ascertained. 
Neither  is  anything  known  about  the  microbe  which 
may  be  assumed  to  be  the  cause  of  typhus  fever. 


VIII.  THE  CHOLERA  MICROBE. 

This  terrible  disease  has  its  origin  in  Asia,  where 
its  ravages  are  as  great  as  those  of  yellow  fever  in 
America.  It  is  endemic  or  permanent  in  the  Ganges 
delta,  whence  it  generally  spreads  every  year  over 
India.  It  was  not  known  in  Europe  until  the  begin- 
ning of  the  century ;  but  since  that  time  we  have  had 
six  successive  visitations,  and  it  seems  destined  to 
replace  the  plague  or  black  death  of  the  Middle  Ages, 
a  disease  which  appears  to  be  now  confined  to  some 
few  localities  of  the  East.* 

In  1817,  there  was  a  violent  outbreak  of  cholera 
at  Jessore,  India.  Thence  it  spread  to  the  Malay 
Islands,  and  to  Bourbon  (1819) ;  to  China  and  Persia 
(1821);  to  Russia  in  Europe,  and  especially  to 
St.  Petersburg  and  Moscow  (1830).  In  the  following 
year  it  overran  Poland,  Germany,  and  England,  and 
first  appeared  in  Paris  on  January  6,  1832;  here  it 
raged  until  the  end  of  September. 

*  See  in  the  Annuaire  de  iJifrapeutique,  1885,  Bouchardat's 
account  of  cholera  epidemics  in  Paris,  together  with  remarks  on  the 
nature,  the  parasite,  the  hygiene,  and  the  treatment  of  cholera. 


196          MICROBES,   FERMENTS,   AND  MOULDS. 

In  1849,  the  cholera  pursued  the  same  route. 
Coming  overland  from  India  through  Russia,  it 
appeared  in  Paris  on  March  17,  and  lasted  until 
October. 

In  1853,  cholera,  again  coming  by  this  route,  was 
less  fatal  in  Paris,  although  it  lasted  for  a  longer  time 
— from  November,  1853,  to  December,  1854. 

The  three  last  epidemics,  18G5,  1873,  and  1884, 
differ  from  the  foregoing  in  not  having  taken  the 
continental  route;  they  came  by  the  Mediterranean 
Sea.  Brought  from  India  to  Egypt  by  the  Mecca 
pilgrims,  the  epidemic  of  1865  entered  France  by  way 
of  Marseilles,  ravaged  Provence  during  the  summer 
of  1865,  and  was  carried  to  Paris  towards  the  end  of 
September  by  a  woman  who  came  from  Marseilles. 
It  was  less  fatal  than  the  preceding  epidemics,  and 
so  also  was  that  of  1873. 

The  epidemic  of  1884  took  the  same  route.  First 
localized  in  Alexandria  (1883),  it  attacked  Naples, 
Marseilles,  and  Toulon  in  the  summer  of  1884,  and 
overran  all  Provence;  thence  it  was  transferred  to 
Nantes,  to  several  towns  in  the  north-west  of  France, 
and  to  Paris,  where  it  was  comparatively  mild.  Finally, 
it  entered  Spain  at  Barcelona  towards  the  end  of  the 
year,  and  ravaged  the  whole  peninsula  through  the 
summer  of  1885.  In  August,  it  also  reappeared  in 
Marseilles  and  Toulon,  and  this  could  not  be  ascribed 
to  a  fresh  importation  from  Spain  or  the  East. 

The  essentially  epidemic  and  contagious  progress 


THE  MICROBES  OF  HUMAN  DISEASES.  11)7 

of  this  disease  clearly  indicates  the  presence  of  a 
microbe,  of  which  the  chosen  seat  is  the  intestines, 
whence  it  passes  with  the  patient's  faeces,  and  con- 
stitutes the  contagious  element  in  places  affected  by 
the  epidemic. 

The  first  precise  micrographic  researches  made  on 
this  subject  were  those  of  the  French  and  German 
commissions  sent  to  Alexandria  in  1883.  Koch, 
member  of  the  German  sanitary  commission,  was 
the  first  to  describe  the  microbe  which  it  has  been 
decided  to  consider  as  the  producing  agent  of  cholera. 
He  gave  it  the  name  of  comma  bacillus  (Bacillus 
komma),  on  account  of  its  form. 

In  order  to  see  these  bacilli  in  any  number,  a  case 
of  malignant  cholera  must  be  observed.  For  this 
reason,  an  unsuccessful  search  for  this  parasite  has 
often  been  made,  since  it  cannot  be  distinguished  from 
the  numerous  other  parasites  found  with  it  in  the 
intestines  of  cholera  patients  on  the  second  or  third 
day.  A  small  fragment  of  the  rice-water  evacuation 
of  cholera  should  be  placed  on  a  glass  slide  and 
stained  with  methyl  violet  or  methylene  blue;  the 
superfluous  liquid  must  be  drained  off,  and  the  pre- 
paration may  then  be  examined  under  a  magnifying 
power  of  from  1200  to  1500  diameters,  making  oat) 
of  an  immersion  lens,  on  which  light  is  thrown  by  an 
achromatic  condenser. 

The  comma  bacilli  then  present  the  appearance 
shown  in  Fig.  87,  and,  in  spite  of  the  colouring  matter, 


198          MICROBES,  FERMENTS,  AND  MOULDS. 

are  full  of  motion  and  activity,  which  they  retain  for 
some  time.  They  are  arched  in  form,  and,  roughly 
speaking,  resemble  a  comma.  Their  length  is  1 J  micro- 
millimetres  to  2  J  micro-millimetres,  and  their  width  is 
0'6  to  07  micro-millimetre.  They  are  often  arranged 
in  chains  or  chaplets,  so  as  to  appear  like  the  letter  S, 
or  several  S's,  placed  end,  to  end  as  we  see  in  Fig.  87. 
These  latter  are  the  most  characteristic.  Compared 


0 


Fig.  87. — Cholera  microbe,  or  Bacillus  Tcomma  (Koch) :  a-e,  the  different  forrrs  which 
it  presents  in  its  growth  and  division  into  cells  (greatly  magnified) ;  1,  2,  cultures 
of  bacillus,  under  a  simple  lens. 

with  the  microbe  of  tuberculosis,  that  of  cholera  is 
shorter  and  thicker.  Its  spiral  shape  has  led  to  the 
belief  that  it  is  an  intermediate  form  between  the 
genera  Bacillus  and  Spirillum. 

Comma-shaped  microbes  may  be  found  in  most 
stagnant  and  running  water,  but  they  are  in  general 
much  larger,  and  none  of  them  present  the  charac- 
teristic dimensions  of  Bacillus  komma. 

This  bacillus  is  found  in  the  riziform  grains  of 
choleraic  evacuations,  which  are,  as  we  know,  formed 


THE  MICROBES  OF  HUMAN  DISEASES.  199 

by  the  desquamation  of  the  mucous  membrane  of  the 
intestines.  The  membrane  is,  in  fact,  literally  flayed 
from  one  end  to  another,  and,  in  consequence  of  its 
congestion,  the  walls  of  the  intestines  are  of  a  bright 
rose  colour.  The  riziform  grains  consist  of  small 
tufts  of  epithelial  cells,  conglomerated  together,  and 
they  contain  numerous  bacilli. 

They  are  also  found  in  the  glands  of  the  intestine 
into  which  they  penetrate,  owing  to  the  desquamation 
of  the  epithelium.  They  have  not  as  yet  been  found 
in  the  kidneys,  the  urine,  or  the  blood. 

Cultures  of  this  microbe  on  gelatine  or  gelose  are 
very  successful.  Koch  has  observed  that  it  readily 
multiplies  in  damp  linen,  or  in  milk,  broth,  eggs, 
moistened  bread,  potatoes,  etc.  The  temperature  most 
favourable  to  it  is  from  30°  to  40°,  and  even  at  20°  it 
still  multiplies  on  gelatine.  Below  16°  it  grows  very 
slowly,  but  does  not  perish.  Cold  does  not  kill  it :  at 
10°  below  zero  it  is  still  alive,  and  capable  of  resuming 
all  its  activity  when  replaced  in  favourable  conditions. 
This  microbe  is  aerobic,  and  soon  dies  when  deprived 
of  air. 

Water  can  serve  as  its  vehicle,  but  docs  not  supply 
sufficient  nutriment,  so  that  it  soon  disappears. 
This,  however,  is  not  the  case  with  stagnant  water 
containing  organic  matter.  When  the  level  of  sub- 
terranean waters  sinks,  the  surface  water  becomes 
more  charged  with  all  kinds  of  refuse,  and  the 
multiplication  of  germs  becomes  more  easy.  Bacilli 


200          MICROBES,   FERMENTS,   AND  MOULDS. 

cultivated  in  distilled  water-die  within  twelve  hours, 
while  they  can  live  for  a  week  in  drinking-water. 
(Cornil.) 

The  influence  of  the  level  of  the  subterranean 
waters  on  the  progress  of  cholera  epidemics  was 
pointed  out  in  Germany  by  Pettenkofer  long  before 
there  was  any  serious  idea  of  regarding  a  microbe  as 
the  cause. 

During  his  recent  travels  in  India,  Koch  met  with 
the  comma  bacillus  in  the  stagnant  waters  of  that 
country. 

For  a  long  while  the  attempt  failed  to  reproduce 
Asiatic  cholera  in  animals  by  injections  of  comma 
bacilli,  and  thus  to  prove  the  parasitic  nature  of  the 
disease.  The  animals  in  countries  attacked  by  cholera 
appear  to  enjoy  immunity  in  this  respect.  Nicati  and 
Rletsch  at  Marseilles  were,  however,  successful  in  pro- 
ducing cholera  by  the  direct  injection  of  choleraic  liquid 
into  the  duodenum  of  guinea-pigs,  dogs,  etc.  Almost 
all  these  animals  died  at  the  end  of  two  or  three  days, 
and  the  inflamed  intestines  contained  a  number  of 
comma  bacilli,  much  more  vigorous  than  those  of  the 
injection. 

Bochefontaine,  of  Paris,  swallowed  pills  which 
contained  choleraic  evacuations.  He  felt  unwell  for 
some  days,  but  no  serious  consequences  ensued.  It 
is  probable  that  in  this  case  the  acidity  of  the  gastric 
juice  attenuated,  or  partially  destroyed  the  bacilli. 
We  shall  see  that  acids  are,  in  fact,  adverse  to  the 


THE  MICROBES  OF  HUMAN  DISEASES.  201 

development  of  the  microbe.  Bochefontaine  also 
injected  the  choleraic  virus  under  the  skin  of  his  arm, 
but  the  operation  was  only  followed  by  an  oedematous 
redness,  localized  round  the  puncture,  and  .the  con- 
stitutional symptoms  were  not  so  marked  as  those 
produced  by  taking  the  same  virus  into  the  digestive 
canal. 

Ferran's  Attempts  at  Inoculation. — This  leads  us 
to  mention  the  attempts  at  inoculation  made  by 
Ferran  on  a  large  scale  in  Spain,  under  the  name  of 
anti-cholera  vaccinations. 

In  1884,  Ferran,  a  Tortosa  physician,  was  sent  by 
the  municipality  of  Barcelona  to  study  the  infectious 
agent  of  cholera  at  Toulon.  His  preceding  studies 
in  micrography  pointed  him  out  for  this  mission. 
He  returned  from  Toulon,  provided  with  cultures  of 
the  comma  bacillus,  and  devoted  himself  to  the 
study  of  its  life-history.  The  facts  reported  by  him 
differ  very  much  from  those  previously  observed,  and 
cannot  be  accepted  without  further  investigation. 

According  to  Ferran,  the  cholera  microbe  presents 
a  polymorphism  which  has  escaped  notice  in  Koch's 
investigations,  and  those  of  the  other  micrographists 
who  have  observed  and  cultivated  it.  When  trans- 
ferred to  a  sterilized  alkaline  infusion,  the  comma 
bacillus  increases  in  length,  forms  sinuous  filaments, 
then  swells  at  one  extremity  until  it  attains  to  the 
volume  of  a  red  blood-corpuscle,  thus  constituting 

an  'oogonium  filled  with  protoplasm.     A  transparent 
10 


202          MICROBES,   FERMENTS,  AND  MOULDS. 

envelope  (periplasma)  then  encloses  the  oogonium, 
which  thus  becomes  an  oosphere.  Close  to  this,  on 
the  original  filament,  a  small  swelling  appears,  which 
Ferran  regards  as  the  pollinidium,  or  antheridium, 
which  is  intended  to  fertilize  the  oosphere  and  trans- 
form it  into  an  oospore. 

When  the  rupture  of  the  oospore  occurs,  the 
granules  contained  in  it  float  in  the  liquid.  Those 
which  have  been  fertilized  grow  until  they  are  as 
large  as  the  original  oogonium,  and  constitute  mul- 
berry-shaped bodies,  so  called  on  account  of  the 
numerous  round  projections  or  micrococci  which 
cause  the  surface  to  resemble  that  fruit. 

A  very  slender  filament  may  soon  be  seen  to  issue 
from  one  of  the  points  of  this  mulberry-shaped  body, 
a  filament  which  grows  longer,  and  sometimes  two 
of  them  appear  at  once.  These  filaments  become 
sinuous,  twist  in  spirals,  form  spirilla,  and  are  then 
segmented  so  as  to  form  by  fission  Koch's  comma 
bacilli,  which  are  the  starting-point  of  the  culture, 
and  of  this  cycle  of  evolution  (Figs.  88,  89,  90). 

Hence  it  would  appear  that  the  cholera  microbe 
must  belong  to  a  much  higher  group  than  that  of 
bacteria,  to  which  it  has  been  hitherto  assigned. 
This  mode  of  reproduction  would  show  that  it  is  not 
an  alga,  but  a  fungus  of  the  group  of  Peronosporece, 
and  it  is,  in  fact,  termed  by  Ferran  P.  Barcinonce 
while  his  friends  prefer  to  call  it  P.  Ferrani,  after,  its 
discoverer. 


THE  MICROBES  OF  HUMAN  DISEASES. 


203 


FeiTan  regards  this  peronospora  as  the  infectious 
agent  of  cholera.  Yet  it  seems  extraordinary  that 
such  a  remarkable  polymorphism  should  have  escaped 
the  observation  of  Koch  and  of  the  numerous  micro- 


Figs.  88,  89,  90.— Evolution  of  cholera  microbe  {Peronnspora  Ferrani:  FerraiO: 
1.  Cholera  microbe  (/iacillus  komma),  discovered  by  Koch.  2.  Spiral  form  of 
bacillus,  transferred  from  gelatine  to  an  infusion.  3.  Degeneration  of  sjmal 
form  after  a  srri.-s  .•!'  successive  cultures.  4.  Cholera  microbe  (/Vrow>.«;x//-a 
Arrant):  development  of  oogonium  on  the  spirilla  and  straight  filain.  nts. 
5.  The  oogonium  is  filled  with  granules  which  centre  in  a  point  k,  and  it  is  then 
converted  into  an  oosphere ;  m,  pollinidium  on  fertili/ing  oigan.  6.  The  oosphere 
is  converted  into  mulberry-shaped  and  comma-shaped  bodies. 

graphists  who  have  made  various  cultures  of  the 
comma  bacillus.  It  is  difficult  not  to  suppose  that 
some  negligence  or  error  has  vitiated  Ferran's  re- 


204          MICROBES,  FERMENTS,  AND  MOULDS. 

searches,  and  the  first  idea  which  will  occur  to  any 
unprejudiced  micrographist,  is  that  P.  Ferrani  is  not 
really  Koch's  comma  bacillus,  and  consequently  not 
the  cholera  microbe.* 

We  have,  in  fact,  already  shown  that  numerous 
comma-shaped  bacteria,  or  free  cells,  are  found  in 
water  and  in  the  human  body,  and  that  these  may 
be  easily  confounded  with  the  true  comma  bacillus 
when  staining  reagents  and  a  very  precise  mode  of 
culture  are  not  employed.  Ferran  himself  states  that 
this  staining  process  must  not  be  used  in  the  culture 
of  P.  Ferrani.  Cornil  has,  however,  shown  that  the 
true  comma  bacillus  is  not  destroyed  by  methyl 
violet.  Finkler  had  previously  discovered  in  cholera 
nostras,  which  is  not  epidemic,  a  comma-shaped 
microbe  resembling  in  many  respects  the  one 
described  by  Ferran.  Koch  has  shown  that  this 
microbe,  as  well  as  one  of  similar  form  found  by 
Lewis  in  the  saliva,  does  not  act  in  cultures  like  the 
microbe  of  Asiatic  cholera ;  Lewis's  microbe  does  not, 
like  the  cholera  bacillus,  liquefy  gelatine. 

The  precautions  necessary  for  the  sowings  of 
culture  liquids  are  so  great  that  we  may  be  permitted 
to  doubt  whether  Ferran  has  always  guarded  against 
error.  Brouardel's  report  shows,  after  a  visit  to 


*  Our  criticism  on  the  description  and  illustrations  of  Laveran's 
marsh-fever  microbe  might  be  applied,  word  for  word,  to  Ferran 's 
description  and  illustrations  of  the  cholera  microbe,  which  we  have 
reproduced  above. 


THE  MICKOBKS  OF  HUMAN  DISEASES.  205 

Ferran's  laboratory,  that  the  instruments  and  methods 
in  use  there  were  primitive  and  insufficient. 

Until  these  facts  have  been  confirmed  by  other 
observers,  it  seems  prudent  to  regard  P.  Ferrani  and 
B.  kortima  as  two  absolutely  distinct  microbes.  It 
does  not  follow  that  the  culture  liquids  employed  by 
Ferran  did  not  contain  the  latter,  but  it  is  probable 
that  it  also  contained,  and  in  larger  numbers,  a  second 
microbe  (?),  which  is  Peronospora  Ferrani. 

It  may  also  be  observed,  the  injection  of  Ferran's 
culture  liquid  into  the  intestines  of  guinea-pigs  pro- 
duced no  effect,  while  subcutaneous  injections  soon 
killed  these  animals  and  distinctly  affected  men.  This 
is  precisely  the  opposite  effect  to  that  observed  by 
Nicati  and  Rietsch  at  Marseilles,  and  by  Bochefontaine 
in  Paris. 

This  is  a  crucial  difference,  since  it  shows  that 
the  two  microbes  are  not  identical,  and  all  our  know- 
ledge of  cholera  tends  to  show  that  its.  microbe  has 
a  special  action  on  the  intestines.* 

However  this  may  be,  Ferran  carried  on  his 
culture  experiments  in  the  endeavour  to  obtain  an 
attenuated  microbe  which  might  serve  for  preventive 
inoculations.  He  believes  that  he  has  succeeded,  and 

*  The  experiments  made  by  Gibier  and  Van  Ermengen  in  August, 
1885,  confirm  this  opinion.  After  inoculating  a  certain  number  of 
guinea-pigs,  according  to  Ferran's  hypodermic  method,  with  a  virulent 
culture  liquid,  and  giving  them  time  to  recover,  the  same  liquid  was 
injected  into  the  stomach  of  these  animals,  and  they  all  died  with  the 
symptoms  and  lesions  of  cholera 


206          MICROBES,  FERMENTS,  AND  MOULDS. 

after  inoculating  himself,  he  performed  the  same 
operation  on  several  of  his  friends ;  then  on  thousands 
of  people  in  different  towns  of  the  province  of  Barce- 
lona, and  throughout  Spain. 

His  inoculation  consists  in  introducing,  by  means 
of  the  small  syringe  used  for  hypodermic  injection, 
about  a  cubic  centimetre  of  the  vaccinal  liquid,  the 
nature  of  which  is  kept  secret  by  its  author.  There 
is  always  a  certain  discomfort  after  the  operation, 
but  it  disappears  at  the  end  of  a  few  hours.  Ferran 
himself  states  that  one  inoculation  will  not  suffice 
to  ward  off  the  contagion.  A  second,  third,  and  even 
more,  are  necessary  for  the  attainment  of  this  object, 
but  the  discomfort  caused  by  the  operation  always 
becomes  less. 

Up  to  this  time  the  results  obtained  by  the  pro- 
cess during  the  recent  epidemic  in  Spain  are  not 
accurately  known,  since  Ferran  has  been  unable  to 
produce  the  official  statistics  which  are  necessary  to 
confirm  his  assertions. 

We  are,  therefore,  entitled  to  reserve  our  judg- 
ment, both  as  to  the  value  claimed  for  this  vac- 
cination, and  as  to  the  true  nature  of  the  microbe 
cultivated  by  Ferran,  and  considered  by  him  to  be 
the  infecting  agent  of  cholera.  If,  again,  we  recur 
to  the  facts  established  by  Bochefontaine,  it  may  be 
asked  whether  subcutaneous  injection  is  the  true 
mode  of  inoculation  applicable  to  this  disease,  and 
if  the  process  adopted  by  Bochefontaine,  of  intro- 


THE  MICROBES  OF  HUMAN  DISEASES.  207 

ducing  the  attenuated  microbe  into  the  stomach  by 
means  of  pills  or  a  liquid,  would  not  be  more  rational. 

Mode  of  Propagation  and  Persistence  of  Cholera. — 
The  upper  part  of  the  delta  of  the  Ganges  seems  to 
be  the  original  home  of  cholera  and  its  microbe. 
Below  this  region,  the  stagnant  water  on  each  side 
of  the  river,  infected  with  every  species  of  ordure/ 
renders  the  maritime  base  of  the  delta  wholly  unin- 
habitable. But  even  in  its  upper  part  the  land  is 
nearly  covered  by  water.  In  order  to  build  a  house, 
the  earth  is  heaped  up  to  raise  the  level  of  the  soil, 
and  the  house  stands  on  the  embankment,  surrounded 
by  water.  A  high  temperature  is  necessary  to  enable 
the  bacillus  to  live  in  water,  and  it  is  probable  that  it 
will  never  become  acclimatized  in  our  colder  climate. 
The  drainage  which  has  been  carried  on  round  Cal- 
cutta has  already  rendered  epidemics  less  serious. 

The  disease  is  always  propagated  by  man.  In 
India,  Arabia,  and  Egypt,  its  diffusion  is  chiefly  owing 
to  pilgrimages.  In  Bengal  the  pilgrims  all  bathe 
together  in  sacred  pools,  often  only  a  few  square 
metres  in  size,  and  receiving  some  thousands  of  men 
in  the  course  of  the  day,  streaming  with  sweat  and 
exhausted  by  long  journeys  and  insufficient  food,  and 
under  such  conditions  cholera  is  often  developed. 
From  India  it  passes  to  Arabia  by  means  of  the 
Mussulman  pilgrims,  whose  caravans  block  the  nar- 
row streets  of  Mecca  every  year,  and  thence  it  is  trans- 
ported to  Egypt.  Finally,  it  is  carried  from  A  lexandria 


208          MICROBES,   FEEMENTS,  AND  MOULDS 

to  Marseilles  and  other  Mediterranean  ports  by  vessels 
which  have  served  for  the  transport  of  pilgrims,  by 
men,  their  linen,  and  other  garments. 

It  is  consequently  by  the  human  body  and  its 
clothing,  or  by  the  water  which  carries  away  human 
faeces  or  has  served  for  the  washing  of  soiled  linen, 
that  the  infecting  microbes  are  carried.  The  air,  as 
it  has  long  been  known,  need  not  be  taken  into 
account.  As  early  as  1832,  it  was  observed  that  the 
wind  did  not  affect  the  epidemic,  which  seemed  rather 
to  advance  like  a  man  travelling  by  short  stages. 

Duclaux's  recent  researches  show  that  the  sun 
and  air  attenuate  and  soon  destroy  the  microbes,  and 
that  only  dead  germs  are  borne  on  the  air  and  wind. 
"In  order  to  retain  their  virulence  unimpaired,  the 
microbes  must  travel  in  packages  of  clothing,  in  bales 
of  merchandise,  or  in  the  close,  moist  hold  of  a  vessel. 
In  a  word,  of  all  agents  of  sanitation,  the  sun  is  at 
once  the  most  universal,  the  most  economical,  and 
the  most  active  to  which  the  guardians  of  public 
and  private  hygiene  can  have  recourse  "  (Duclaux). 

Koch  has  declared  that  acids  in  general  are  the 
greatest  hindrance  to  the  development  of  the  cholera 
bacillus.  In  this  way,  the  acid  of  the  gastric  juice 
is  the  best  safeguard,  and  many  cases  of  contagion 
may  be  explained  by  the  fact  that  the  large  quantity 
of  water  imbibed  has  diluted  the  gastric  juice  to 
excess,  or  else  that  the  source  of  contagion  has 
rapidly  passed  through  the  empty  stomach,  and 


THE  MICROBES  OF  HUMAN  DISEASES.  209 

has  carried  a  liquid  containing  dangerous  microbes 
straight  into  the  intestines.  Indigestion,  and  catarrh 
of  the  stomach  and  intestines,  of  which  diarrhoea  is 
a  symptom,  constitute  predisposing  causes  of  the 
disease. 

Among  other  substances  unfavourable  to  the  de- 
velopment of  the  microbe,  and  thus  constituting  a 
preventive  of  cholera  up  to  a  certain  stage,  we  may 
mention  calcium  sulphate,  which  acts  by  producing 
sulphuretted  hydrogen  gas,  also  carbolic  acid,  salicylic 
acid,  thymol,  alcohol,  acetic  acid  or  vinegar,  and 
mustard  oil,  which,  like  the  other  volatile  substances 
already  mentioned,  constitutes  an  excellent  antiseptic 
in  an  epidemic  of  cholera. 

We  shall  speak  in  another  chapter  of  the  purity 
of  drinking-water,  which  is  of  great  importance,  and 
of  the  improved  filters  invented  to  eliminate  the 
microbes  which  are  not  arrested  by  ordinary  filters. 


IX.    THE  EXANTHEMATA:    SCARLATINA,  SMALL-POX, 
MEASLES,  VACCINIA. 

Microbes  are  found  in  the  eruptions  characteristic 
of  all  these  diseases.  They  are  generally  micrococci, 
isolated  or  in  chaplets. 

Measles. — Babes,  in  1880,  was  the  first  to  describe 
the  micrococci  which  he  observed  in  this  disease,  and 
especially  in  the  pneumonia  by  which  it  is  often  com- 


210          MICEOBES,   FERMENTS,   AND  MOULDS. 

plicated.  The  blood  of  the  eruption,  the  catarrhal 
secretion  of  the  nose,  etc.,  contain  small  round 
bodies,  isolated  or  in  pairs  (in  the  form  of  the  figure 
8),  or  more  rarely  in  short  chaplets.  When  there  is 
decided  pneumonia,  the  pulmonary  alveoli  likewise 
contain  isolated  bacteria,  in  the  form  of  an  8,  in 
chaplets,  and  even  in  zoogloea,  or  massed  together. 
Babes  has  not  yet  cultivated  nor  tried  to  inoculate 
this  microbe. 

More  recently,  in  January,  1883,  Le  Bel  observed, 
in  the  urine  of  persons  attacked  by  measles,  the 
appearance  of  slightly  curved  rods  (bacillus)  capable 
of  very  slow  movements.  Their  length  varies  con- 
siderably, and  the  spores  appear  in  a  swelling  which 
occurs  at  about  a  third  of  the  length  of  each  rod. 
This  microbe  appears  for  a  few  days  at  the  beginning 
of  the  fever,  and  disappears  with  the  fever,  to  return 
afresh  at  the  moment  when  peeling  begins.  We  know 
that  these  are  the  two  epochs  of  contagion.  The 
microbe  is  found  in  this  scurf,  and  may  be  obtained 
by  scraping  the  skin  with  a  knife.  Le  Bel  succeeded 
in  cultivating  it  in  sterilized  urine.  In  serious  cases 
of  measles,  the  microbe  remains  upon  the  skin  and  in 
the  urine  for  weeks,  and  even  months.  It  is  probable 
that  Babes' s  micrococcus  and  Le  Bel's  bacillus  are  only 
two  forms  of  the  same  microbe. 

Scarlatina. — Pohl  has  found,  in  the  desquamating 
epidermic  cells  of  this  disease,  and  on  the  soft  palate, 
micrococci  of  somewhat  smaller  size  than  those  of 


THE  MICROBES  OF  HUMAN  DISEASES.  211 

measles.  A  bacterium  in  the  form  of  an  8  has  also 
been  found  in  the  urine  of  scarlet-fever  patients. 

Stickler  believes  that  he  has  discovered  a  vaccine 
for  scarlatina,  by  passing  its  virus  through  the  horse 
or  the  cow.  When  these  animals  are  inoculated  with 
the  blood  of  a  man  suffering  from  the  disease,  an 
eruption  accompanied  by  desquamation  occurs  three 
days  after  inoculation.  A  man  inoculated  with  this 
desquamation  displayed  a  rash  resembling  that  of 
scarlatina,  and  when  the  same  man  was  afterwards 
inoculated  with  human  scarlatina,  he  did  not  take  the 
disease. 

Small-pox  and  Vaccinia. — We  find  in  small-pox 
pustules  micrococci,  either  isolated  or  united,  which 
may  be  seen  on  a  section  of  the  skin  if  they  are 
coloured  with  methyl  violet.  The  same  microbe  may 
be  observed  on  the  pustules  of  the  mucous  membrane 
of  the  larynx,  in  the  liver,  the  kidneys,  and  the  blood 
of  the  vena  portse.  The  attempt  to  cultivate  it  has 
hitherto  failed. 

The  micrococcus  found  in  small-pox  pustules  does 
not  differ  in  its  form  from  that  of  cow-pox  in  cows, 
which  constitutes,  as  we  know,  the  original  source 
of  human  vaccine.  It  is  not  yet  certain  that  the 
microbes  of  small-pox  and  vaccinia  are  identical,  but 
from  the  resemblance  of  the  pustules  and  of  the  micro- 
cocci  contained  in  them,  it  is  most  probable  that  this 
is  the  case,  and  this  would  explain  why  vaccine  is 
efficacious  as  a  preventive  of  small-pox. 


212          MICEOBES,   FERMENTS,  AND  MOULDS. 

It  may  be  useful  to  retrace  here  the  curious  history 
of  vaccine,  since  it  is  directly  interesting  to  us  all 


. .        „.      «.    .        ;. . _ . 


•!:•&"'''  '^&$'£:^ 


Fig.  91. — .Section  of  skin  covering  a  small-pox  pustule,  a,  horny  layer  of  the 
epidermis ;  d,  adenoid  tissue ;  m,  m,  micrococci  stained  with  methyl  violet  ( X 
850  diam.). 

Before  vaccine  was   discovered,  inoculation   with 
small -pox  was   practised  as  a  preventive  measure. 


THE  MICROBES  OF  HUMAN  DISEASES.  213 

This  inoculation  was  known  to  the  Arabs  and  Chinese 
as  early  as  the  tenth  century,  but  it  was  decried  by 
physicians,  and  only  practised  by  women.  In  India 
it  was  practised  by  the  Brahmins,  and  a  public  crier 
announced  that  he  had  small-pox  virus  to  sell. 

In  1717,  Lady  Mary  Wortley  Montague,  wife  of 
the  English  Ambassador  in  Constantinople,  chanced 
to  see  the  operation  performed  by  an  old  Thessalian 
woman,  who  always  accompanied  the  puncture  with 
practices  of  witchcraft  and  superstitious  usages.  She 
asserted  that  the  Virgin  herself  had  appeared  to  reveal 
the  secret  to  her,  and  boasted  of  having  performed 
inoculation  in  more  than  40,000  cases.  Lady  Mary 
was  so  much  impressed  by  the  results  obtained  that 
she  had  her  son  inoculated,  and  it  is  said  that  the  old 
Thessalian  handled  her  rusty  needle  so  unskilfully 
that  Maitland,  the  physician  attached  to  the  embassy, 
was  obliged  to  finish  the  operation.  On  her  return  to 
England,  Lady  Mary  made  the  success  of  the  experi- 
ment generally  known.  George  L  authorized  the 
inoculation  of  six  prisoners  in  Newgate,  and  then  of 
six  orphans.  The  operation  was  performed  by  Mait- 
land and  crowned  with  success,  and  he  was  then 
allowed  to  inoculate  members  of  the  royal  family, 
and  more  than  200  other  persons. 

The  practice  was,  however,  condemned  by  the 
clergy,  who  considered  it  to  be  immoral  and  anti- 
religious,  as  being  opposed  to  the  divine  rights  and 
will.  Some  failures,  such  as  the  death  of  Lord  Sunder- 


214          MICROBES,   FEKMENTS,  AND  MOULDS. 

land's  son,  awakened  alarm,  and  caused  inoculation  to 
be  discredited. 

Notwithstanding  this,  it  was  introduced  into  France 
in  1723  by  De  La  Costa,  and  aacepted  by  Chirac, 
Helvetius,  and  by  other  physicians  of  the  day. 
Although  opposed  by  the  majority,  and  officially  con- 
demned by  a  decree  of  the  Sorbonne  in  1753,  as  "  un- 
lawful and  contrary  to  the  law  of  God  " — a  decree 
officially  confirmed  by  the  faculty  of  medicine  in  1763 
—inoculation  continued  to  be  practised  up  to  the 
time  when  vaccination  was  substituted  for  it. 

Vaccination  appears  to  have  been  practised  in 
Asia  in  earlier  times.  However  this  may  be,  it  was 
known  in  the  south  of  France  that  farm  servants  who 
had  been  affected  by  cow-pox  were  secured  against 
srnall-pox.  These  pustules  generally  occur  on  the 
udder,  and  the  milkers  were  inoculated  with  the 
vaccine  matter,  through  some  accidental  scratch  on 
their  hands.  Rabault,  a  Frenchman,  communicated 
this  fact  in  1798  to  Pew,  an  English  physician  and 
a  friend  of  Jenner.  To  Jenner  we  must  assign  the 
merit  of  understanding  the  importance  of  this  fact, 
and  deducing  from  it  one  of  the  most  admirable  dis- 
coveries of  modern  medicine,  the  preventive  method 
which  continually  tends  to  become  more  general,  and 
to  be  extended  to  other  diseases,  especially  since 
Pasteur's  late  researches  into  vaccination  for  anthrax 
and  for  fowl-cholera. 

Pasteur  has  also  shown  t        the  microbes  are  the 


THE  MICHOBES  OF  HUMAN  DISKASES.  215 

active  principle  of  the  vaccine  virus.  The  liquid  need 
only  be  deprived  by  filtration  of  its  micrococci  in 
order  to  become  inert,  and  consequently  unfit  for  use 
in  vaccination. 


X.  THE  MICROBES  OF  CROUP  AND  WHOOPING-COUGH. 

The  parasitic  nature  of  croup  and  diphtheria,  which 
had  long  been  suspected,  was  only  shown  in  1881 
by  the  researches  of  two  American  physicians,  Wood 
and  Formad.  In  the  spring  of  that  year  a  very 
serious  epidemic  of  croup  occurred  at  Ludington,  a 
small  town  on  the  borders  of  Lake  Michigan.  Here 
the  principal  industry  is  derived  from  the  neighbouring 
forests,  the  trees  of  which  are  sawn  into  planks  in  the 
numerous  saw-pits,  and  thus  employ  almost  the  whole 
working  population.  The  town  stands  on  a  height, 
with  the  exception  of  one  quarter  of  it,  which  is  built 
on  very  low,  marshy  ground,  partly  filled  up  with  saw- 
dust. Here  the  soil  is  so  wet  that  when  a  small  hole 
is  dug,  it  fills  with  water  immediately,  and  cellars  are 
almost  unknown.  It  was  in  this  quarter  that  the 
epidemic  was  so  severe ;  almost  all  the  children  were 
attacked  by  it,  and  a  third  of  them  had  already  died. 

Formad  went  to  Ludington  to  study  the  epidemic 
and  collect  materials  for  experiments.  In  all  these 
cases  of  croup,  the  blood  was  full  of  micrococci  belong- 
ing to  Micrococcus  diphthericus,  some  detached,  others 


216          MICROBES,  FERMENTS,  AND  MOULDS. 

united  in  the  form  of  zoogloea,  that  is  agglutinated  in 
small  masses ;  others,  again,  in  the  colourless  corpuscles 
of  the  blood.  All  the  organs,  and  especially  the 
kidneys,  were  likewise  filled  with  them. 

With  the  materials  gathered  at  Ludington,  Wood 
and  Formad  made  some  experiments  in  cultures,  and 
were  able  to  inoculate  rabbits  with  croup.  These 
inoculations  were  made  subcutaneously,  in  the  muscles 
and  trachea,  and  were  followed  by  the  production  of 
false  membranes,  and  the  animals  died  with  all  the 
symptoms  of  diphtheria.  The  blood  was  full  of  micro- 
cocci.  An  examination  of  living  animals  showed  that 
the  micrococcus  first  attacked  the  colourless  corpuscles, 
within  which  their  vibratile  motion  could  be  observed. 
The  corpuscle  changed  in  appearance,  the  granules  dis- 
appeared, and  it  became  so  full  of  rnicrococci  that  they 
could  no  longer  move :  they  grew  until  they  caused  the 
rupture  of  the  corpuscle,  and  then  escaped  in  the  form 
of  an  irregular  mass,  which  constitutes  the  zoogloea. 
Corpuscles  filled  with  micrococci  were  found  in  the 
false  membrane ;  in  the  small  vessels,  which  they  dilate 
and  completely  obliterate ;  and  even  in  the  marrow  of 
the  bones. 

Cultures  made  in  flasks  afforded  important  results. 
A  comparison  of  the  sowings  made  with  micrococci 
collected  at  Ludington  with  those  found  in  the 
ordinary  diphtheritic  angina,  which  is  common  at  Phila- 
delphia, showed  a  great  difference  in  the  vitality  and 
virulent  properties  of  microbes  derived  from  these  two 


THE  MICROBES  OF  HUMAN    DISEASES.  217 

sources.  The  former  multiplied  rapidly  and  energeti- 
cally, succeeding  each  other  up  to  the  tenth  generation, 
while  those  from  Philadelphia  only  went  to  the  fourth 
or  fifth  generation,  and  those  taken  from  the  tongue 
did  not  go  beyond  the  third.  It  must  be  observed  that 
the  diphtheritic  angina  of  Philadelphia  is  much  less 
fatal  than  croup,  and  the  first  attempts  at  inoculation 
made  by  Formad  and  Wood  produced  doubtful  results, 
precisely  because  they  were  made  with  the  microbe 
of  diphtheritic  angina,  which  is  an  attenuated  form 
of  the  microbe  of  croup.  The  organism  is  the  same, 
but  it  is  modified  by  the  medium  in  which  it  is 
developed,  and  the  vitality  of  artificial  cultures  is  in 
direct  proportion  to  the  malignity  of  the  disease  from 
which  the  germs  for  sowings  are  derived. 

The  following  theory  may  be  deduced  from  these 
facts,  which  will  explain  all  cases  of  diphtheria : — A 
child  contracts  a  simple  catarrhal  angina,  or  laryngitis ; 
the  micrococci,  which  up  to  this  time  remained  inert 
in  the  mouth,  begin  to  grow  and  multiply  under  the 
influence  of  the  inflammatory  products  which  favour 
their  development ;  the  plant  which  has  been  dormant 
becomes  widely  diffused.  There  are  many  degrees 
between  croup  with  malignant  complications  and  the 
mildest  form  of  diphtheritic  angina,  as  all  practical 
physicians  know.  More  or  less  numerous  germs  of 
micrococci  float  in  the  air,  or — which  appeared  to  be 
the  case  at  Ludington — are  conveyed  in  drinking- 
water,  and  they  may  encounter  more  or  less  favourable 


218          MICROBES,  FERMENTS,  AND  MOULDS. 

conditions.  If  they  settle  on  a  child's  tender  throat 
predisposed  for  their  reception  by  slight  inflammation, 
they  develop  there  with  frightful  rapidity,  and 
produce  croup,  and  then  diphtheria,  which  is  soon 
fatal.  Nageli  calculates  that  their  number  may  be 
doubled  within  twenty  minutes.  The  plant,  of  which 
the  activity  is  increased  by  its  culture  in  the  person  of 
one  patient,  may  be  expelled  with  the  breath  so  as 
to  infect  another  individual.  And  just  as  there  are 
different  degrees  of  activity  in  the  plant,  so  the  spores 
may  be  more  or  less  contagious,  and  those  of  malig- 
nant diphtheria  are  more  to  be  feared  than  those  of 
the  ordinary  diphtheritic  angina. 

When  we  consider  the  remedies  to  be  employed 
against  the  ravages  of  this  cruel  disease,  it  should 
first  be  observed  that  the  only  effect  of  the  operation 
of  tracheotomy,  which  is  successful  in  barely  a  third 
of  the  cases,  is  to  admit  air  into  the  child's  lungs. 
Its  first  curative  effect,  therefore,  consists  in  saving  the 
child  from  the  asphyxia  by  which  it  is  threatened, 
and  in  giving  time  to  apply  remedies,  but  another 
explanation  is  necessary  when  this  operation  alone  is 
enough  to  effect  a  cure.  Pasteur  has  shown  that  pro- 
longed contact  with  the  air  produces  a  real  attenuation 
of  virulent  microbes.  Wood  and  Formad  have  estab- 
lished similar  facts,  for  when  the  false  membranes  of 
croup  procured  at  Ludington  had  been  exposed  to  the 
air  for  several  weeks,  until  they  were  completely 
desiccated,  they  became  perfectly  inert,  notwithstand- 


THE  MICROBES  OF  HUMAN  DISEASES.  219 

ing  their  former  virulence.  They  were,  however,  not 
dead,  since  they  were  still  capable  of  reproduction,  but 
only  up  to  the  third  or  fourth  generation.  It  must, 
therefore,  be  admitted  that  the  free  access  of  air  given 
by  tracheotomy,  may  attenuate  the  virulence  of  the 
micrococcus  of  croup. 

Too  much  cannot  be  said  against  the  misuse  of 
emetics,  which  is, unfortunately,  very  common,  since  they 
are  readily  administered  by  parents  without  medical 
advice.  A  regular  emetic  of  which  the  action  is 
much  more  violent  than  that  of  ipecacuanha  should 
never  be  given.  The  micrococci  are  only  found  in 
the  most  superficial  layers  of  the  false  membranes, 
and  when  these  are  removed,  an  irritated  and  bleeding 
mucous  membrane  remains,  which  had  been  previously 
protected  by  the  false  membrane  from  immediate 
contact  with  the  microbes:  these  now  pass  without 
difficulty  into  the  blood.  Thus  the  ground  may  be 
said  to  be  prepared  and  rendered  more  favourable 
for  the  multiplication  of  the  micrococci,  which  are 
sown  there  afresh,  and  are  reproduced  with  frightful 
rapidity. 

The  most  effectual  remedy  has  been  prescribed  by 
Dr.  Fontaine  of  Bar-sur-Seine.  It  consists  in  admin- 
istering sulphurous  drugs,  in  the  form  of  sulphate 
of  calcium,  so  as  to  produce  in  the  stomach  a 
slow  disengagement  of  sulphuretted  hydrogen  gas, 
which  checks  the  development  of  microbes,  or  attenu- 
ates their  virulence.  It  need  scarcely  be  said  that 


220          MICROBES,   FERMENTS,  AND  MOULDS. 

this  treatment  must  begin  at  once,  before  the  micro- 
cocci  have  penetrated  into  the  blood.  At  the  same 
time  a  gargle  of  lemon-juice  or  citric  acid  should  be 
used,  which  shrivels  up  the  false  membranes  without 
forcibly  detaching  them.  The  action  of  this  acid  is 
explained  by  the  fact  that,  for  the  most  part,  microbes 
only  thrive  in  an  alkaline  medium.  By  this  treat- 
ment Fontaine  has  been  able  to  save  nine-tenths  of 
his  patients,  while  all  other  modes  of  treatment 
have  only  succeeded  in  a  third  of  the  cases,  and  the 
proportion  is  often  much  smaller. 

The  first  researches  made  in  Europe  on  the 
microbe  of  diphtheria  date  from  1873,  at  which  time 
Klebs  gave  an  exact  description  of  it  under  the 
name  Microsporon  diphtericum.  In  most  cases  he 
observed  two  forms :  micrococci  and  rods  or  bacilli. 
Struck  by  the  great  difference  in  intensity  which  the 
disease  presents  in  different  epidemics,  he  states  in 
his  later  works  that  there  are  two  kinds  of  diphtheria, 
due  to  the  predominance  of  one  or  other  of  these  two 
forms,  one  of  which  he  terms  microsporine,  and  the 
other  bacillary.  The  former  may  be  observed  in  the 
east  of  Europe,  and  especially  in  Hungary;  while 
the  latter  is  more  common  in  Switzerland  and  the 
west,  including  France.  The  first  is  chiefly  found 
upon  the  tonsils,  and  is  less  serious;  while  the  bacillary 
form  soon  attacks  the  larynx  and  trachea,  and  pro- 
duces blood-poisoning,  which  is  rapidly  fatal.  The 
bacilli  which  are,  like  those  of  tuberculosis,  very 


THE  MICROBES  OF  HUMAN  DISEASES.  221 

minute,  remain  on  the  surface  of  the  false  membranes, 
more  rarely  witnin  them,  and  on  the  surface  of  the 
inflamed  mucous  membrane. 

Loffler  undertook  experiments  in  culture  and 
inoculation  which  confirm  Klebs'  opinion.  He  suc- 
ceeded in  isolating  and  cultivating  separately  the 
Microsporon,  or  micrococcus,  and  the  bacillus,  which 
makes  it  probable  that  these  are  two  distinct  species. 
The  chaplets  of  micrococci,  cultivated  separately  and 
used  to  inoculate  animals,  do  not  produce  diphtheria ; 
the  bacilli,  on  the  other  hand,  cause  the  formation  of 
false  membranes,  but  do  not  exactly  reproduce  the 
diphtheria  of  the  human  subject. 

Cornil  and  Babes  have  likewise  studied  these  two 
fonns  of  microbes.  They  have  ascertained  that  the 
bacilli  are  more  generally  found  in  the  false  mem- 
branes of  the  skin,  and  the  micrococci  in  those  of  the 
throat  and  larynx.  But  in  almost  all  cases  they  have 
found  bacilli,  zoogloea,  and  chaplets  of  micrococci 
associated  together  in  the  false  membranes,  even  in 
those  of  the  skin,  and  bacilli  in  those  of  the  throat. 

Cornil  and  Megnin  have  studied  the  spontaneous 
diphtheria  of  poultry  and  domestic  quadrupeds.  The 
anatomical  lesions  and  the  form  of  the  microbes 
approximate  to  those  of  human  diphtheria,  and  cases 
of  contagion  between  the  calf  and  man  have  been 
observed.  Yet  direct  inoculation  has  failed,  so  that  it 
is  still  impossible  to  affirm  the  identity  of  the  two 
diseases. 


222          MICROBES,   FERMENTS,   AND  MOULDS. 

We  do  not  think  that  the  dual  nature  of  human 
diphtheria,  indicated  by  the  researches  of  Klebs  and 
Loffler,  is  yet  established.  The  symptoms,  and  still 
more  the  histological  lesions  of  this  disease,  are  in 
favour  of  its  unity,  and  it  may  be  owing  to  other 
causes  that  the  disease  is  more  or  less  severe. 

The  well-known  polymorphism  of  microbes  leads 
us  to  think  that  the  bacilli  represent  the  adult  form, 
and  the  micrococci,  or  Microsporon,  the  early  form  of 
a  single  species,  which  is  in  all  cases  the  cause  of 
diphtheria  and  of  its  several  manifestations — croup, 
diphtheria,  etc.  Further  researches  are  necessary  to 
decide  this  question. 

Whooping-cough  and  Influenza. —  Burger  has 
lately  discovered  rods  in  the  form  of  an  8  in  the 
sputum  of  whooping-cough ;  they  are  found  in  great 
numbers  in  the  white  scum,  and  are  even  visible  to 
the  naked  eye,  and,  like  many  other  bacteria,  they 
can  be  stained  by  methyl  violet.  To  this  microbe 
whooping-cough  and  its  relapses  are  due,  and  it  is 
always  present.  It  has  not  yet  been  cultivated. 

Influenza  resembles  whooping-cough  in  the  course 
it  takes,  and  is  probably  also  caused  by  microbes. 
Letzerich  has  found  micrococci  in  the  blood,  to  which 
he  ascribes  this  disease,  but  his  researches  must  be 
repeated  with  greater  care. 

Certain  facts  observed  in  medical  practice  have 
led  to  the  surmise  that  whooping-cough  may  be  re- 
garded as  an  attenuated  form  of  croup,  just  as  vaccinia 


THE  MICKOBES  OP  HUMAN  DISEASES.  223 

is  an  attenuated  form  of  small-pox.  The  same  treat- 
ment applies  to  both  diseases.  When  the  patient  is 
kept  in  the  purifying  chamber  of  a  gas  manufactory, 
where  there  is  a  constant  disengagement  of  acid 
vapours,  sulphuretted  hydrogen,  hydro-carbons,  coal 
tar,  benzine,  carbolic  acid,  etc.,  the  microbes  embedded 
in  the  throat  and  lungs  are  attenuated.  Sulphate  of 
calcium  is  a  successful  remedy  in  whooping-cough  as 
well  as  in  croup. 

Children  who  have  had  whooping-cough,  or  who 
are  passing  through  the  disease,  rarely  contract  croup 
even  when  it  is  epidemic,  although  catarrh,  inflamma- 
tion of  the  bronchial  tubes,  ulceration  of  the  mouth, 
and  general  debility,  are  all  predisposing  causes  of 
croup.  The  question  therefore  arises  whether  whoop- 
ing-cough does  not  act  as  a  sort  of  preventive  vaccina- 
tion which  may  serve  as  a  protection  against  croup. 
Further  researches  and  observations  should  be  made 
in  this  direction,  if  that  which  we  now  indicate  can 
be  established  as  a  fact. 


XI.  THE  MICROBES  OF  PHTHISIS  AND  OF  LEPROSY. 

These  two  microbes  are  so  similar  in  form  that  it 
is  necessary  to  have  recourse  to  chemical  reagents  and 
to  staining  processes  in  order  to  distinguish  them 
clearly.  Both  assume  the  form  of  an  8,  or  of  slender, 
elongated  rods,  so  minute  that  it  is  not  surprising 


224          MICROBES,  FERMENTS,  AND  MOULDS. 

that  the  bacillus  should  have  so  long  eluded  the 
observation  of  the  physiologists  who  have  studied  the 
tubercle  of  phthisis  under  the  microscope.  The  form 
of  both  microbes  assigns  them  to  the  genus  bacillus. 

The  experiments  of  Villemin,  begun  ten  or  twelve 
years  ago,  first  showed  the  parasitic  nature  of  tuber- 
culosis, or  pulmonary  phthisis.  Villemin  inoculated 
rabbits  with  tubercular  matter,  showing  that  the 
disease  was  essentially  contagious.  More  recently 
Toussaint  and  Koch  have  cultivated  the  microbe  in 
a  closed  vessel,  and  have  inoculated  animals  with  the 
produce  of  the  culture;  all  these  animals  died  with 
symptoms  of  tuberculosis. 

The  still  more  recent  researches  of  Cornil,  as  he 
stated  in  May,  1883,  before  the  Academy  of  Medicine, 
have  confirmed  the  parasitic  nature  of  this  terrible 
disease.  The  microbe  has  been  found  in  the  giant 
cells  of  the  tubercle  and  in  the  sputum  of  consumptive 
patients  ;  it  has  been  found  in  the  colourless  corpuscles 
of  the  blood,  by  which  it  is  conveyed  into  all  parts  of 
the  system,  and  it  is  also  found  in  all  the  organs  in 
which  a  tubercle  can  be  developed. 

The  bacillus  of  tuberculosis  is  somewhat  smaller 
than  that  of  leprosy.  Each  bacillus  is  from  three  to 
four  micro-millimetres  in  length.  They  are  generally 
found  associated  in  the  form  of  chains  or  chaplets — at 
any  rate,  this  is  the  case  in  the  sputum,  as  we  see  in 
Fig.  91  A.  Koch  has  cultivated  them  in  gelatinized 
blood-serum.  Their  growth  is  very  slow. 


THE  MICROBES  OF  HUMAN  DISEASES. 


225 


Now  that  this  is  known,  it  is  easy  to  explain  the 
facts  of  direct  contagion  which  are  so  frequent  among 
people  living  together,  and  especially  from  a  husband 
to  a  wife,  or  conversely.  Since  the  breath  of  a  con- 
sumptive patient  is  always  charged  with  germs  of 
the  microbe,  which  abound  in  the  cavities  in  which 


>lW$g-£.    \\ 


Fig.  91  A.— Bacilli  in  ine  pputum  of  a  consumptive  patient :  A,  bacilli,  either  isolated 
(a)  or  in  the  fpitli-lial  (/>)  and  pigmentc-d  (c)  cells  of  the  lung;  B,  numerous 
bacilli,  mas-ed  together  in  the  sputum.  Stained  by  Ehrlich's  process  with 
methyl  violet  (much  enlarged). 


the  sputum  is  formed,  it  could  not  possibly  be  other- 
wise. The  following  statements  of  facts  are  taken  from 
Debove's  clinical  lectures  at  the  Hospital  de  la  Pitie. 

"Jean,  a  tuberculous  patient,  was  married  to 
Antoinette,  a  young  woman  with  no  previous  tendency 
to  tuberculosis.  Jean  died,  and  his  wife  became 
phthisical.  She  was  remarried  to  Louis,  who  had 
likewise  no  phthisical  taint;  Louis  and  Antoinette 
both  died  of  phthisis.  The  niece  of  the  latter,  equally 
without  phthisical  taint,  contracted  the  disease  in 
nursing  her  aunt,  then  married,  and  her  husband  was 
11 


226  MICROBES,  FEEMENTS,   AND  MOULDS. 

in  his  turn  attacked  by  phthisis.  All  these  people 
resided  in  a  place  in  which  it  was  easy  to  verify  the 
absence  of  hereditary  taint." 

Here  are  other  observations  of  the  same  nature  :— 

"  A  young  woman  without  hereditary  taint  nursed 
a  phthisical  patient  and  contracted  phthisis.  She 
returned  home,  and  communicated  the  disease  to  the 
six  sisters  with  whom  she  lived.  One  sister  survived, 
but  she  was  not  living  with  her  family. 

"  A  soldier  became  phthisical  while  with  his  regi- 
ment, and  was  therefore  discharged,  and  returned  to 
his  family.  His  father,  mother,  two  brothers,  and  a 
neighbour  who  nursed  them,  became  phthisical.  Yet 
none  of  them  were  predisposed  by  hereditary  taint. 

"  A  girl  returned  from  school  in  consumption ;  on 
her  death  her  room  and  clothes  passed  to  her  sister, 
who  died  of  the  same  disease.  A  third  sister  died 
under  like  conditions.  As  their  parents  still  survive, 
it  is  clear  that  the  disease  was  not  due  to  heredity." 

This  does  not  imply  that  heredity  plays  no  part 
in  the  transmission  of  the  disease,  for  the  contrary  is 
proved ;  yet  such  transmission  often  occurs  after  the 
child  is  born,  and  sometimes  the  nurse  by  whom  it 
is  suckled  may  be  the  source  of  contagion. 

In  the  case  of  children  brought  up  by  hand,  the 
infection  may  come  from  cow's  milk  which  has  not 
been  boiled.  Cows  are  often  attacked  by  tuberculosis, 
and  numerous  bacilli  have  been  found  in  the  teats  and 
milk  of  these  animals.  This  indicates  the  necessity 


THE  MICROBES  OF  HUMAN  DISEASES.  227 

of  boiling  the  milk  used  for  food,  especially  in  the 
case  of  children,  at  any  rate  when  the  source  is  un- 
known.* 

Phthisis  is,  as  we  know,  a  slow  disease,  probably 
because  the  microbe  is  anaerobic,  and  lives  within  the 
cellular  tissue,  not  in  the  blood,  which  it  merely  tra- 
verses. The  slow  progress  of  the  disease  explains  the 
cases  of  spontaneous  cure  effected  by  the  expulsion  of 
the  microbe  in  the  sputum,  or  by  the  tubercles  passing 
into  a  cretaceous  condition,  which  causes  the  destruc- 
tion of  the  bacteria  encysted  in  them.  Hence  also 
the  fact  that  all  the  causes  which  weaken  the  consti- 
tution, bad  food,  overwork,  inflammatory  diseases, 
pregnancy,  etc.,  hasten  the  end  of  consumptive  per- 
sons. Those  who  are  attacked  by  the  disease  may, 
if  rich  enough  to  live  in  the  South,  and  to  follow 
with  care  the  hygienic  prescriptions  of  the  physician, 
often  attain  an  advanced  age,  in  spite  of  the  lesions 
which  remain  latent  in  the  organism,  provided  also 
they  commit  no  imprudence  in  the  matter  of  diet. 

It  is  therefore  important  to  maintain  the  strength 
of  consumptive  patients  by  tonics,  by  a  nourishing  diet, 
and  by  an  hygiene  as  strictly  protective  as  possible. 
The  good  effects  of  creosote,  of  sulphur  waters,  etc., 
are  due,  as  in  diphtheria,  to  the  attenuation  of  the 

*  This  precaution  is  equally  efficacious  to  ward  off  typhoid  fever. 
In  several  epidemics  of  this  disease,  and  especially  in  England,  inquiry 
has  shown  that  milk  was  the  vehicle  of  contagion,  either  from  the 
water  with  which  it  was  adulterated,  or  from  that  which  was  used 
to  wash  the  vessels  in  which  it  was  placed. 


228 


MICROBES,   FERMENTS,   AND  MOULDS. 


virulent  properties  of  the  microbe.  Hansen  considers 
that  alkalis,  not  acids,  are  the  best  antiseptics  in  this 
disease. 

Tubercular  leprosy,  termed  elephantiasis  by  the 
ancients,  is  caused  by  tubercles  seated  in  the  skin, 
and  containing  a  bacillus  greatly  resembling  that  of 
phthisis,  but  larger  (Fig.  92).  This  microbe  is  anae- 


Fig.  92.— Bacilli  of  leprosy,  encysted  in  the  subcutaneous  connective  tissue  of  the  skin 
(^much  enlarged). 

robic,  and  can  only  live  in  the  dermic  cells,  in  which 
it  is  encysted.  Hence  the  treatment  which  experi- 
ence, preceding  the  theory,  showed  to  be  the  most 
efficacious :  instead  of  keeping  the  ulcers  covered,  they 
should  be  exposed  to  the  air  and  sun,  often  washed, 
and  kept  as  clean  as  possible.  This  disease,  which  is 
essentially  contagious,  is  very  rare  in  Europe,  but 
common  in  Egypt  and  throughout  Asia. 


THE  MICROBES  OF  HUMAN  DISEASES.  229 

XII.  THE  MICROBE  OF  PNEUMONIA. 

One  of  the  most  important  micrographic  dis- 
coveries of  late  years  is  that  a  microbe  is  always 
present  in  inflammation  of  the  lungs,  or  pneumonia. 
This  disease  was  long  considered,  and  is  still  con- 
sidered by  the  majority  of  doctors,  to  be  altogether 
independent  of  any  parasitic  infection.  It  is  such 
a  matter  of  tradition,  both  among  patients  and  their 
doctors,  to  ascribe  this  disease  to  accidental  causes, 
and  especially  to  a  sudden  chill,  that  the  parasitic 
doctrine  of  pneumonia  at  once  encountered  a  lively 


Fig.  93.— Micrococci  in  sputum  of  pneumonia :  b,  d,  free,  or  encysted  in  the  lymphatic 
cells  o,  c ;  n,  nuclei  of  cells  (much  enlarged). 

opposition.  It  is,  however,  now  impossible  to  deny 
the  important  part  taken  by  microbes  in  the  trans- 
mission of  this  disease. 

The  microbe  of  pneumonia  was  discovered  by 
Friedlander  and  Talamon  in  1882.  It  consists  of 
micrococci,  often  associated  in  an  8  or  in  short  chains 
(Fig.  93),  and  found  in  the  sputum  and  lungs  of 
pneumonic  patients,  either  detached  or  encysted  in  the 
lymphatic  cells. 


230          MICROBES,   FERMENTS,   AND  MOULDS. 

Under  a  strong  magnifying  power,  this  micrococcua 
is  seen  to  be  shaped  like  a  lance-head,  and  short  rods, 
terminating  in  a  cone,  are  found  with  it.  It  is  probable 
that  the  micrococcus  is  the  early  form  of  the  microbe, 
which  becomes  a  bacillus  in  the  adult  form  (Cornil). 

The  presence  of  a  microbe  in  pneumonia  explains 
many  facts  which  had  remained  obscure  in  this 
disease,  especially  the  epidemics  in  a  room  or  house, 
when  several  persons  living  together  are  successively 
attacked  by  pneumonia.  It  likewise  explains  the 
resemblance,  which  has  long  been  indicated  by  their 
common  name,  between  the  pneumonia  of  man  and 
the  contagious  pneumonia  of  cattle,  which  is  well 
known  to  be  essentially  epidemic,  transmissible  by 
contact  and  inoculation. 

A  culture  of  the  microbe  of  pneumonia  can  be 
made,  and  when  it  is  inoculated  into  the  tissue  of  the 
lung,  it  produces  in  animals  a  true  pneumonia. 


XIII.  SOME  OTHER  DISEASES  CAUSED  BY  MICROBES. 

We  shall  only  say  a  few  words  about  several  other 
diseases,  admitted  to  be  contagious,  and  in  which  the 
presence  of  a  special  microbe  has  been  ascertained. 

In  the  pus-corpuscles  of  gonorrhoea,  very  minute 
and  mobile  inicrococci  may  be  observed,  often  associated 
in  pairs,  in  fours,  or  in  a  small  mass,  but  rarely  in 
chaplets  (Fig.  94). 


THE  MICROBES  OF  HUMAN  DISEASES.  231 

The  same  micrococcus,  or,  at  any  rate,  a  microbe 
which  cannot  be  distinguished  from  it,  is  often  found 
in  the  purulent  ophthalmia  of  new-born  infants.  It 
is  difficult  to  admit,  even  when  we  make  allowance 
for  the  great  susceptibility  of  an  infant's  eyes  at  the 
moment  of  birth,  that  such  ophthalmia  is  always  of 
gonorrhoeal  origin.  However  this  may  be,  the 
micrococci  of  purulent  ophthalmia  resemble  those  of 
gonorrhoea,  and  the  same  treatment  is  applicable. 
The  solution  of  nitrate  of  silver  in  a  diluted  form, 
generally  employed  in  maternity  hospitals,  as  a  pre- 


Flg.  94. — Cells  of  gonorrhceal  pus  24  hours  after  Its  discharge.  Within  may  be  seen 
several  forms  of  fission  of  their  nuclei,  and  micrococci  moving  in  the  protoplasm 
(x  GOOdiam.). 

ventive    treatment    of   infant    ophthalmia,   has  con- 
siderably reduced  the  intensity  of  this  disease. 

The  red,  malodorous  sweat  of  the  armpits  is  due 
to  the  presence  of  a  microbe,  which  is  found  free  in 
the  sweat,  or  massed  in  the  form  of  a  zoogloea,  and 
adherent  to  the  hair  of  the  skin.  The  red  colour  is 
not  due  to  iron,  for  no  trace  of  this  metal  is  revealed 
by  analysis ;  it  approximates  in  its  nature  to  that  of 
Micrococcus  prodigiosus.  It  may  be  cultivated  in 


232          MICROBES,  FERMENTS,  AND  MOULDS. 

white  of  egg  at  a  temperature  of  37°,  in  which  it 
retains  its  characteristic  colour. 

In  a  sweating  foot,  of  which  the  smell  is  so 
offensive,  Rosenbach  found  a  short,  thick  rod,  which 
i§  at  once  aerobic  and  anaerobic,  is  rapidly  developed, 
and  retains  its  offensive  smell  when  cultivated  (Fig.  95). 

In  the  gangrene  of  long  bones,  the  same  observer 


*         •• 

Fig.  95.— Bacillus  of  Fig.  96.— Saprogenic  bacillus 

feet-sweat.  of  osseous  gangrene. 

has  found  a  similar  bacillus,  which,  like  the  foregoing 
one,  produces  by  inoculation  a  local  affection,  more  or 
less  strongly  marked  (Fig.  96). 

Warts. — We  know  that  a  wart  is  self-sown,  and 
appears  to  contain  a  contagious  principle.  This  is 
Tomasi  Crudeli's  Bacterium  porri,  and  is  minute  and 
in  the  form  of  an  8. 

Among  the  diseases  due  to  microbes  we  must 
include  mumps,  epidemic  goitre,  epithelial  xerosis  of 
the  eye,  polypus  of  the  nasal  canal,  of  which  the 
concretions  are  formed  of  Streptothrix  Forsteri,  etc. 


XIY.  THE  MICROBE  OF  ERYSIPELAS. 

Erysipelas  belongs  both  to  internal  and  external 
pathology.    It  is  sometimes  manifested  as  a  special- 


THE  MICROBES  OF  HUMAN  DISEASES.  233 

primary  disease,  characterized  by  the  inflammation  of 
the  skin,  and  sometimes  as  a  secondary  complication 
of  wounds,  sores,  and  surgical  operations.  In  any  case, 
the  course  taken  by  the  disease  and  its  contagious 
nature  enables  us  to  assume  the  presence  of  a  microbe. 
Martin,  Volkmann,  and  Hliter  found  bacteria  in  the 
patches  of  skin ;  and  Hayem  found  them  in  the  pus  of 
meningitis,  which  followed  erysipelas  of  the  face. 
Lukomski  was  able  to  inoculate  rabbits  with  the 
disease,  which  may  also  be  communicated  by  vaccine 
lymph,  taken  from  a  child  suffering  from  erysipelas. 
Fehleisen  has  cultivated  the  microbe  in  a  pure  state, 


Fig.  97. — Section  of  the  Pkin  in  erysipelas :  the  interfascicular  space  (e)  is  full  of 
microbes  (m)  in  8's  or  chains;  t,  connective  tissue  (x  600  diain.). 

and  has  inoculated  man  with  it,  always  reproducing 
erysipelas  with  its  characteristics  and  typical  course. 
Antiseptics,  such  as  carbolic  acid  and  analogous  sub- 
stances, employed  either  as  outward  applications  or  as 
subcutaneous  injections,  have  been  successful  in  many 
instances  in  arresting  the  development  of  the  disease. 

Erysipelas  serves  as  the  transition  to  those  diseases 
within  the  domain  of  surgery,  and  which  are  generally 
due  to  sores,  wounds,  and  operations. 


234          MICKOBES,  FERMENTS,   AND  MOULDS. 


XV.  MICROBES  OF  Pus;  PYAEMIA  AND  SEPTICAEMIA. 

Sores  and  surgical  operations  are  often  followed 
by  a  general  poisoning  of  the  blood  and  of  the  whole 
system — a  severe  affection  which  is  rapidly  fatal,  and 
characterized  by  the  presence  of  pus-corpuscles  in  con- 
siderable numbers  in  the  blood  and  in  the  principal 
organs.  Together  with  these  pus-corpuscles  there  is 
always  a  special  microbe,  termed  Micrococcus  septicus, 
which,  like  that  of  diphtheria,  may  either  appear  free 
or  in  the  form  of  chaplets  (vibrio),  or  in  the  interior 
of  the  colourless  corpuscles  of  pus,  or  embryonic  cells, 
of  which  it  effects  the  rupture  in  the  form  of  zoogloea. 

This  microbe,  or  others  of 
allied  species,  are  the  im- 
mediate cause  of  that  poison- 
ing of  the  blood  which  is 
termed  pyaemia,  septicaemia, 
traumatic  fever,  puerperal 
fever,  post-mortem  wounds, 
etc.  The  germs  of  Micro- 

Fig.  98.— Pus-corpuscles  of  puerperal 

Eu°sn(xs'8ol)u«l!amf).micr  coccus    septicus    are    intro- 

duced  into  the  blood,  and 

multiply  there,  through  the  exposed  surface  of  a  wound, 
or  sometimes  by  means  of  the  instrument  which  caused 
it  (Fig.  98). 

When  the  instrument  causing  the  wound  is  charged 
with  microbes,  it  is  not  necessary  that  the  wound 


THE  MICROBES  OF  HUMAN  DISEASES.  235 

should  be  gaping :  there  is  in  this  case  a  true  inocula- 
tion. Such  is  the  case  in  a  post-mortem  wound.  The 
experiments  of  T4denat,  of  Lyons,  show  that  when 
decomposition  has  not  begun  in  the  corpses  of  healthy 
persons,  who  have  died  by  violence,  the  autopsy  pre- 
sents no  danger ;  but  this  is  not  the  case  when  death 
is  due  to  an  infectious  disease,  pyaemia,  erysipelas,  etc. 
On  the  other  hand,  the  puncture  will  have  no  evil 
results  if  the  bleeding  is  profuse,  or  if  the  microbes 
and  their  germs  have  been  removed  by  immediate 
suction.  Some  hours  after  death,  all  corpses  contain 
microbes,  which  have  penetrated  into  the  blood  owing 
to  the  softening  of  the  tissues,  and  which  either  come 
from  the  external  air  or  from  the  digestive  canal. 

The  enormous  number  of  pus-corpuscles  which 
appear  in  a  very  short  time  in  the  blood  was  for  a 
long  while  a  problem  for  physicians.  It  is  now  known 
that  these  corpuscles  have  their  source  not  only  in  the 
wound,  but  also  in  all  parts  of  the  vascular  system, 
and  especially  in  the  capillaries,  according  to  SchifFs 
theory.  The  microbian  theory  may  easily  be  made 
to  agree  with  the  latter,  and  Sternberg  was  the  first 
to  suggest  that  it  appears  to  be  the  function  of  the 
colourless  corpuscles  to  take  possession  of  the  bacteria 
introduced  into  the  blood,  and  to  destroy  them.  We 
know,  in  fact,  that  the  colourless  corpuscles  do  take 
possession  of  all  foreign  particles,  such  as  micrococci  and 
bacteria,  introduced  into  the  blood,  and  in  some  sense 
encyst  them  in  their  protoplasm.  When  these  bacteria 


236          MICROBES,  FERMENTS,   AND  MOULDS. 

multiply  in  the  blood,  they  must  necessarily  have  an 
irritating  effect  on  the  walls  of  the  blood -capillaries 
and  this  appears  in  the  swelling  of  the  cells  and  their 
return  to  the  spherical  form ;  in  a  word,  they  are 
transformed  into  embryonic  or  migratory  cells  (accord- 
ing to  Cohnheim's  theory).  These  do  not  differ,  or 
only  differ  slightly,  from  the  colourless  corpuscles  of 
the  blood,  and  are  pus-corpuscles.  This  new  theory 
is  in  accordance  with  the  facts  daily  presented  to  us 
in  the  treatment  of  surgical  diseases. 


XVI.  MICROBES  OF  SOME  OTHER  DISEASES,  RESULTING 
FROM  WOUNDS. 

Whitlow  and  Agnail. — These  two  complaints  are 
produced  by  pricking  the  finger  with  some  instru- 
ment charged  with  microbes.  Chains  of  bacteria  or 
micrococci  are  always  found  in  the  collection  of  pus 
or  serous  discharge. 

Boil  and  Carbuncle. — The  pus  from  a  boil  contains 
micrococci,  which  Pasteur  first  observed,  and  which  he 
has  cultivated  in  an  infusion  of  yeast  and  in  chicken- 
broth. 

It  was  found  by  Rosenbach  in  osteomyelitis,  and 
was  termed  by  him  Staphylococcus  pyogenus  aureus 
(Fig.  99). 

Carbuncle  only  differs  from  a  boil  in  its  larger 
size,  and  contains  the  same  microbe.  It  is  well  known 


THE  MICROBES  OF  HUMAN  DISEASES. 


237 


Fig.  99.— Boil  microbe 

(Stcti>h  ifltwc ii a  pi/o- 
genusdurtus:  Rosen- 
bach). 


that  it  is  readily  and  spontaneously  self-inoculated, 
and  that  boils  and  carbuncles  rarely  occur  singly 
in  the  same  individual.  Diabetic 
patients  are  very  subject  to  this 
affection,  yet  the  microbe  does  not 
admit  of  culture  in  sugared  water. 

Phlegmon. — This  is  the  name  given 
to  the  suppuration  of  the  subcutaneous  cellular  tissue, 
caused  by  contusions,  wounds,  and  medical  injections 
of  morphia  or  any  other  sub- 
stance. Microbes  are  always 
found  associated  in  8's  or  in 
long  sinuous  chains  (Fig. 
100).  In  all  these  cases  there 
has  been  some  communica- 
tion with  the  outer  air,  for 
wounds  which  are  really  sub- 
cutaneous— fractures,  for  ex- 
ample — even  when  accom- 
panied by  abundant  haemorr- 
hage, heal  without  suppuration,  and  microbes  are  not 
present. 


Fig.  100. — Pus  of  phlegmon,  contain- 
ing chains  of  micrococci  (x  1UOO 
diam.). 


XVII.  MODE  OF  ACTION  OF  MICROBES  IN  DISEASE. 
PTOMAINES. 

The  question  how  microbes  act  in  disease  has  long 
been  doubtful,  but  the  progress  of  science  tends  to 
clear  away  obscurity. 


238          MICKOBES,  FEKMENTS,  AND  MOULDS. 

The  first  idea  was  that  microbes  introduced  into  the 
blood  or  tissue  of  an  animal  acted  like  parasites  of 
a  higher  organism — intestinal  worms,  for  instance — by 
deriving  their  nourishment  from  their  medium,  and 
developing  at  its  expense.  It  is  evident  that  this 
must  be  the  case,  and  that  in  anthrax,  or  splenic  fever, 
for  example,  the  bacilli  which  swarm  in  the  blood 
abstract  from  the  red  corpuscles  the  oxygen  they 
require,  and  thus  produce  asphyxia  and  the  death  of 
the  animal. 

Yet  it  often  happens,  even  in  anthrax,  that  death 
is  so  rapid,  that  the  bacilli  have  not  yet  had  time  to 
develop  in  the  blood  in  numbers  sufficient  to  produce 
such  fatal  effects.  So,  again,  in  cholera,  the  comma 
bacillus  has  not  yet  been  found  in  the  blood,  and  yet 
cases  of  sudden  death  are  not  uncommon  in  this 
disease.  Some  other  explanation  is  therefore  required. 

Panum  first  showed,  from  the  study  of  the  pro- 
ducts of  putrefaction,  that  a  poisonous  substance, 
resembling  snake- venom  and  vegetable  alkaloids,  is 
developed  as  the  ultimate  product  of  the  putrid  fer- 
mentation of  organic  matter.  Twelve  milligrammes  of 
this  substance  kill  a  dog,"  while  neither  ammonia  nor 
the  acids  which  are  first  formed  in  this  fermentation  can 
produce  septicaemia.  Bergemann  and  Schmiedeberg 
have  termed  this  poisonous  substance  septine. 

Panum's  researches  have  been  recently  resumed  by 
Selmi  and  Gautier,  who  have  extracted  from  corpses 
and  putrefying  organic  matter  a  certain  number  of 


THE  MICKOBES  OF  HUMAN  DISEASES.          239 

poisonous  substances  greatly  resembling  vegetable 
alkaloids,  and  termed  by  them  ptomaines. 

The  action  of  ptomaines  may  be  compared  to  that 
of  strychnine.  Injected  into  the  blood,  even  after 
the  removal  of  every  living  microbe,  the  ptomaines 
produce  fever,  rigors,  vomiting,  diarrhoea,  spasms, 
torpor,  collapse,  and  finally  death.  It  is  probable  that 
in  some  cases  of  poisoning  by  tainted  meat  or  fish 
their  poisonous  properties  are  due  to  the  presence  of 
ptomaines. 

But  in  all  cases  these  ptomaines  are  shown  to  be 
the  product  of  putrid  fermentation,  which  is  always 
effected  in  dead  bodies  by  special  microbes.  Here  the 
ptomaines  are  due  to  the  work  of  the  microbes  of 
putrefaction,  and  are  made  by  them,  just  as  alcohol 
and  the  carbonic  acid  of  alcoholic  fermentation  are 
made  by  yeast,  at  the  expense  of  the  sugared  liquid 
in  which  they  live  and  multiply. 

Direct  experiments  show  that  when  septine,  from 
which  every  microbe  has  been  removed,  is  injected 
into  the  human  subject,  it  produces  feverish  disturb- 
ance, but  only  causes  death  when  introduced  in  con- 
siderable quantities.  If,  on  the  other  hand,  there  is 
in  the  same  individual  a  large  suppurating  wound, 
exposed  to  the  air  instead  of  being  covered  by  an  air- 
tight dressing,  a  purulent  infection  (septicaemia)  will 
almost  certainly  ensue,  since  the  microbes  introduced 
by  means  of  this  wound  will  find  in  it  a  favourable 
soil  (pus  and  putrefying  organic  matter);  they  will 


240          MICROBES,  FEEMENTS,  AND  MOULDS. 

multiply  in  immense  numbers,  and  manufacture  of 
these  materials  a  great  quantity  of  septic  poison,  at  the 
expense  of  the  organism  in  which  they  are  developed. 

It  is  now  admitted  that  the  chief  action  of  patho- 
genic microbes,  or,  at  any  rate,  of  the  most  dangerous 
among  them,  consists  in  the  ptomaines  which  they 
secrete  within  the  body.  This  explains  why  death  by 
cholera  is  so  rapid  and  even  sudden,  when  the  comma 
bacillus  is  still  only  found  in  the  intestines.  Although 
this  micro-organism  has  not  been  absorbed  by  the 
intestinal  mucous  membrane  and  carried  into  the 
blood,  the  poisonous  alkaloid,  or  ptomaine,  which  it 
secretes  is  certainly  present,  and  to  this  the  nervous 
symptoms,  such  as  cramp,  etc.,  which  characterize  this 
disease,  may  probably  be  ascribed. 

Pouehet  has  extracted  from  the  faeces  of  choleraic 
patients,  a  special  alkaloid  of  the  nature  of  ptomaine ; 
and  quite  recently,  in  August,  1885,  he  has  found  traces 
of  the  same  alkaloid  in  infusions  of  pure  culture  of 
Koch's  comma  bacillus.* 

In  conclusion,  at  the  present  stage  of  our  know- 
ledge, it  may  be  admitted  that  the  action  of  patho- 
genic microbes  on  the  system  is  complex,  and  may 
be  analyzed  as  follows: — (1)  The  action  of  a  living 

*  This  affords  the  germ  of  the  idea  of  a  new  process  for  preparing 
lymph,  which  has  perhaps  already  been  put  in  practice.  A  Spanish 
physician  states  that  the  secret  process  employed  by  Ferran  simply 
consists  in  filtering  his  culture  infusion  by  means  of  the  Chamberland 
filter,  and  using  this  liquid  for  inoculation,  since  it  contains  the 
ptomaine  of  cholera  without  its  bacillus  (?). 


THE  MICROBES  OF  HUMAN  DISEASES.          241 

parasite,  which  is  nourished  and  multiplies  at  the 
expense  of  the  fluids  and  gases  of  the  system  ;  (2)  the 
formation  by  this  parasite  of  a  poisonous  substance 
(ptomaine),  of  which  the  elements  are  derived  from  the 
organism,  and  it  acts  as  a  poison  on  this  organism. 


242  MICE013ES,   FERMENTS,   AND  MOULDS. 


CHAPTER  VI. 

MEANS   OF   DEFENCE   AGAINST   MICROBES. 

I.    ANTISEPTIC  TREATMENT   OF  WOUNDS:    GUE"RIN'S 
PROTECTIVE  DRESSING;  LISTER'S  DRESSING. 

THE  first  and  most  brilliant  application  of  the  theory 
of  microbes  to  human  therapeutics  has  been  made  in 
the  treatment  of  wounds. 

Since  it  is  admitted  that  the  danger  of  a  wound 
or  of  a  surgical  operation  is  chiefly  due  to  the  contact 
of  the  wound  with  the  external  air,  which  is  laden 
with  germs,  or  with  the  dressing  which  may  contain 
microbes,  all  the  surgeon's  efforts  should  be  directed 
to  preventing  such  contact.  This  may  be  accom- 
plished by  several  processes,  now  generally  employed 
by  surgeons,  and  these  may  be  regarded  as  the  noblest 
achievement  of  modern  surgery. 

In  Guerin's  protective  dressing,  this  skilful  surgeon 
has  made  a  practical  use  of  Tyndal's  and  Pasteur's 
researches  into  the  nature  of  air-germs.  We  have 


MEANS  OF  DEFENCE  AGAINST  MICROBES.      243 

already  said  that  air  filtered  through  a  sufficiently  thick 
layer  of  cotton  wool  becomes  free  from  germs.  Guerin 
covers  that  part  of  the  body  in  which  the  wound  is 
situated  with  several  layers  of  cotton  wool,  carefully 
applied  and  confined  by  a  cotton  bandage.  This 
dressing  permits  the  access  of  air  to  a  certain  extent, 
but  the  air  is  filtered  through  the  cotton  wool,  which 
arrests  all  microbes ;  and  this  is  proved  by  removing 
the  dressing  after  the  lapse  of  several  days,  when  the 
wound  will  be  found  to  be  in  a  satisfactory  state,  and 
in  process  of  healing.  A  certain  amount  of  pus  is 
produced,  but  much  less  than  in  the  old-fashioned 
lint  dressing,  and  this  pus  is  not  putrefied,  since  the 
germs  which  are  the  agents  of  putrefaction  have 
been  excluded. 

The  English  surgeon,  Lister,  has  arrived  at  the 
same  result  by  a  more  complicated  process,  which 
has,  however,  been  generally  adopted  in  France.  His 
process  is  based  on  the  use  of  carbolic  acid  as  an 
antiseptic  or  destructive  agent  of  microbes  and  germs. 
Whenever  an  operation  is  to  be  performed,  the  instru- 
ments, the  surgeon's  hands,  those  of  his  assistants, 
and  all  the  materials  used  for  dressing,  must  be 
steeped  in  a  sufficiently  dilute  solution  of  carbolic 
acid ;  throughout  the  operation  the  wound  must  be 
surrounded  with  a  spray  of  the  same  solution,  playing 
over  the  hands  of  the  surgeon  and  over  all  he  touches. 
The  same  solution  and  the  same  precautions  are 
applicable  to  the  treatment  of  all  wounds,  whatever 


244          MICROBES,   FERMENTS,   AND  MOULDS. 

be  their  origin,  and  should  be  renewed  whenever  the 
wound  is  dressed. 

We  cannot  describe  Lister's  dressing  in  detail,  but 
will  only  mention — (1)  that  the  skin  surrounding  the 
region  of  the  operation,  the  surgeon's  hands,  and  the 
instruments  are  washed  with  a  carbolic  solution  of  two 
to  three  per  cent. ;  (2)  the  spray  contains  one  per  cent, 
of  carbolic  acid ;  (3)  the  ligature  of  the  arteries  is  done 
with  carbolized  catgut,  which  is  eventually  dissolved 
in  the  wound ;  (4)  the  drainage-tube  usually  arranged 
for  the  outflow  of  the  discharge  is  likewise  carbolized ; 
(5)  so  also  are  the  eight  folds  of  gauze,  which  is 
used  instead  of  linen  dressings ;  (6)  a  protective,  con- 
sisting of  green  oiled  silk,  steeped  in  carbolic  acid 
and  varnished  like  court-plaister,  is  interposed  to 
prevent  the  irritating  effect  of  the  gauze  on  the 
wound  ;  (7)  an  impermeable  mackintosh,  laid  between 
the  seventh  and  eighth  folds  of  gauze,  prevents  the 
penetration  of  fluids. 

The  admirable  results  obtained  by  Lister's  method 
are  the  strongest  confirmation  of  the  truth  of  the 
theory  of  microbes.  Since  its  introduction  into 
medical  practice,  mortality  among  the  wounded  and 
among  the  surgical  patients  has  considerably  diminished, 
and  operations  formerly  considered  impracticable  have 
been  undertaken  and  successfully  carried  out. 

Carbolic  acid  is  not  the  only  antiseptic  which 
affords  excellent  results  by  destroying,  or  at  all  events 
by  attenuating,  the  virulence  of  microbes  and  their 


MEANS  OF  DEFENCE  AGAINST  MICROBES.      245 

germs.  Alcohol,  which  has  been  long  in  use,  boracic 
acid,  salicylic  acid,  thymol  (essence  of  thyme),  and 
eucalyptol  (the  essence  extracted  from  Eucalyptus 
globulus),  and  many  other  substances,  have  been 
employed  both  internally  and  externally  with  this 
object,  and  most  of  them  take  a  more  or  less  impor- 
tant place  in  the  therapeutics  of  those  diseases  caused 
by  microbes. 


IL   HYGIENE    OF   DRINKING-WATER  :   WATER  FREE 
FROM  MICROBES;  CHAMBERLAND  FILTER. 

The  researches  carried  on  by  Miquel  for  some  years 
at  the  Observatory  of  Montsouris,  at  the  Pantheon, 
and  in  other  parts  of  Paris,  teach  us  that  living 
bacteria  are  more  rare  in  the  atmosphere  than  had 
been  generally  supposed.  We  have  already  said  that 
air  is  the  great  purifier  of  microbes,  which  it  destroys 
by  desiccation.  Even  in  the  infection  of  wounds,  it 
is  probable  that  the  liquids  and  linen  formerly 
employed  for  dressings  transported  the  microbes  in 
greater  number  than  the  air,  however  charged  it 
might  be  with  these  organisms  in  the  neighbourhood 
of  a  hospital. 

In  the  water  which  supplies  large  towns,  whether 
furnished  from  wells  or  streams,  a  large  number  of 
microbes  are,  however,  found  in  a  state  of  perfect  vitality. 
This  is  quite  natural,  since  we  know  that  these  plants 


246          MICROBES,  FERMENTS,  AND  MOULDS. 

cannot  exist  without  moisture,  and  they  find  in  such 
water  the  organic  matter  which  nourishes  them.  The 
rivers  receive  them  by  the  sewers  which  discharge  into 
them,  the  wells  by  infiltration  of  the  soil,  and  thus 
in  times  of  epidemic,  the  microbes  of  typhoid  fever 
and  of  cholera  are  always  to  be  found  in  running  or 
stagnant  waters,  which  therefore  become  the  vehicle 
of  infectious  diseases. 

Well-water,  owing  to  its  stagnant  nature,  and  to 
the  infiltration  to  which  it  is  liable  from  cesspools 
which  are  often  leaky,  is  more  dangerous  than 
running  water.  About  two  years  ago,  an  epidemic 
of  typhoid  fever,  which  occurred  in  one  quarter  of 
Angers,  was  stopped  by  introducing  a  supply  of  water 
from  the  Loire ;  up  to  that  time  well-water  had  been 
exclusively  in  use. 

Well-water  in  Bread- making. — In  many  places 
well-water  is  still  too  often  used  for  making  bread 
instead  of  running  water.  There  are  probably  many 
reasons  for  this  preference.  Bakers,  without  assigning 
any  reason  for  the  fact,  assert  that  well-water  causes 
the  bread  to  rise  better ;  and  moreover,  in  towns,  such 
as  Angers,  where  there  is  a  water  company,  river- 
water  costs  money,  while  well-water  may  be  had  for 
nothing.  About  50  per  cent,  of  water  is  used  in 
making  bread,  which  explains  the  preference  shown 
by  bakers  for  well-water,  and  also  the  importance 
ascribed  by  hygienists  to  the  purity  of  the  water 
used  in  bread-making. 


MEANS  OP  DEFENCE  AGAINST  MICROBES.     247 

In  fact,  direct  experiments,  made  with  a  maximum 
registering  thermometer  enclosed  in  the  dough,  shows 
that  the  internal  temperature  of  the  loaf,  that  of  the 
crumb,  rarely  rises  to  100°.  We  know  that  this  tem- 
perature does  not  suffice  to  destroy  most  microbes, 
still  less  their  germs,  for  which  a  temperature  of  from 
115°  to  160°  is  necessary. 

In  1884,  Bouvet,  a  chemist,  and  Preaubert,  a  pro- 
fessor at  the  Lyce'e,  were  commissioned  by  the  munici- 
pality of  Angers  to  make  a  microscopic  examination  of 
numerous  specimens  of  well-water  used  by  bakers  in 
their  trade  in  different  parts  of  the  town.  The  exami- 
nation of  deposits,  either  obtained  spontaneously  by 
allowing  the  water  to  stand  for  twenty-four  hours,  or 
by  testing  the  water  with  osmic  acid,  in  accordance 
with  Certes's  process,  almost  invariably  revealed  the 
presence  not  only  of  the  ova  of  ascarides,  but  of 
numerous  microbes  —  some  of  them  harmless,  like 
Bacterium  termo ;  others  doubtful,  on  account  of  their 
forming  chains  like  the  micrococcus  (two  species  of 
different  form),  and  resembling  Micrococcus  diphtke- 
ricus.  Now,  croup  may  be  regarded  as  endemic  at 
Angers.  In  four  wells  out  of  the  twenty-five  ex- 
amined these  microbes  were  found  in  great  numbers. 
It  must  be  noted  that  micrococci  are  not  found  in 
strongly  aerated  water,  but  only  in  that  of  which 
the  organic  deposit  is  abundant. 

"Well-water  must,  therefore,  be  generally  condemned, 
both  for  drinking  purposes  and  for  the  making  of 


248  MICROBES,  FERMENTS,   AND  MOULDS. 

bread.  Spring-water,  and  still  more  river-water,  as 
it  is  now  supplied  in  towns  by  a  system  of  pipes, 
is  not  free  from  organic  matter,  nor  from  microbes, 
although  they  are  less  abundant  than  in  well-water. 
Purification  is  therefore  necessary. 

With  this  object,  it  is  recommended,  especially  in 
times  of  epidemic,  to  boil  the  water,  so  as  to  destroy 
the  microbes  contained  in  it.  But  this  process  expels 
the  gases,  and  reduces  the  proportion  of  salts  in  solu- 
tion, thus  rendering  the  water  heavy  and  indigestible. 
It  has,  therefore,  -been  suggested  that  only  weak 
mineral  waters  should  be  drunk,  such  as  that  of 
Saint  Galmier,  which,  if  taken  at  the  source  and 
immediately  placed  in  hermetically  sealed  bottles, 
contains  very  few  microbes.  But  this  process  is 
costly,  so  that  only  rich  people  can  avail  themselves 
of  it.  The  most  practicable  mode  of  purifying  table- 
water  and  rendering  it  wholesome  is  by  the  use  of 
filters. 

Ordinary  Filters.  Ckamberland's  Microbe  Filter. 
— Every  one  is  acquainted  with  the  common  filter, 
made  with  crushed  sandstone,  charcoal,  etc.,  which 
should  be  found  in  all  households  and  kitchens.  This 
generally  suffices  to  free  water  from  organic  matter, 
and  especially  from  the  ova  of  ascarides  (intestinal 
worms),  which,  when  introduced  into  the  system, 
develop  and  cause  inconvenience  to  so  many  children, 
and  even  to  grown  persons.  It  is  impossible  to  insist 
too  strongly  on  the  fact  that  the  presence  of  ascarides 


MEANS  OF  DEFENCE  AGAINST  MICROBES.      249 

in  the  intestines  is  always  due  to  the  use  of  unfiltered 
water,  and  this  should  enforce  the  general  use  of 
filters,  which  is  often  neglected  even  by  those  who 
cannot  be  deterred  by  the  relatively  moderate  cost 
of  an  instrument  which  it  is  almost  impossible  to 
wear  out.  An  ordinary  filter,  however,  can  arrest  a 
very  small  proportion  of  microbes,  which  are  much 
more  minute  than  the  ova  of  ascarides. 

A  filter  has,  therefore,  been  devised,  so  perfect  as 
to  allow  the  passage  of  no  solid  matter  in  suspension, 
not  even  the  most  minute  organisms  contained  in 
drinking-water.  This  result  is  effected  by  the  filter 
invented  by  Chamberland  in  Pasteur's  laboratory. 
The  filter  is  formed  (Fig.  101)  of  a  vessel  of  biscuit- 
ware,  A,  shaped  like  a  candle  (whence  its  name  of 
bougie  Chamberland) ;  this  is  Fastened  to  the  lower 
part  of  the  metallic  receiver  D,  which  receives  under 
pressure  the  water  coming  from  the  cock  E.  This 
vessel  consequently  filters  the  water  from  without  to 
within,  and  it  flows  through  the  orifice  B,  perfectly 
free  from  solid  particles,  as  it  appears  from  a  micro- 
graphic  examination. 

Fitted  to  the  distributing  water-taps  of  many 
houses  in  Paris,  and  especially  in  lyc£es,  the  Cham- 
berland filter  acts  under  the  normal  pressure  of  the 
water-conduit,  and,  by  a  new  modification  of  the 
inventor,  can  even  act  without  such  pressure.  For 
this  purpose  he  arranges  his  filters  in,  a  battery,  from 

eight  to  ten  or  more,  in  a  cylindrical  receiver,  closed 
12 


250          MICROBES,  FERMENTS,   AND  MOULDS. 

in  its  upper  part.     This  receiver  is  connected  by  a 
caoutchouc  tube  with  the  vessel  which  contains  water 


Fig.  101.— Section  and  elevation  of  Chamberland's  filter. 

for  filtering.     When  the  vessel  is  placed  two  or  three 
metres  above  the  filter,  from  fifteen  to  twenty  litres 


MEANS  OF  DEFENCE  AGAINST  MICROBES.     251 

of  perfectly  pure  water  may  be  obtained  in  the  course 
of  an  hour.  Under  the  pressure  of  the  taps  of  the 
Paris  water-supply,  the  jet  of  the  filtered  water  is 
as  strong  as  that  of  the  pipes  used  for  watering  our 
gardens;  in  fact,  it  gives  out  four  or  five  litres  a 
minute  under  the  pressure  of  two  or  three  atmospheres. 

Preservation  of  Alimentary  Substances.  Appert's 
Protective  Process,  etc. — We  have  already  said  that 
organic  substances  may  be  preserved  unchanged  for 
an  indefinite  time,  as  long  as  they  are  protected  from 
the  microbes  and  germs  in  the  air.  This  was  shown 
by  Pasteur's  exhaustive  experiments.  He  took  urine 
and  blood,  and  transferred  them  directly  from  the 
animal  organs  into  glass  flasks  which  had  been  pre- 
viously sterilized  or  deprived  of  all  germs.  These 
flasks  were  hermetically  closed  and  kept  for  forty-five 
days.  When  opened  at  the  end  of  that  time,  it  was 
ascertained  that  the  smell  and  appearance  of  the 
liquids  were  unchanged,  that  no  putrid  gas  had  been 
developed,  and  even  that  some  of  the  oxygen  in  the 
flasks  had  not  been  absorbed. 

Most  of  the  processes  in  use,  even  before  this 
experiment,  for  the  preservation  of  food  substances, 
are  only  the  practical  application  of  this  principle : 
the  exclusion  of  microbes  and  germs. 

Appert's  process,  now  so  generally  used  to  preserve 
meat  and  vegetables,  consists  in  enclosing  the  sub- 
stances to  be  preserved  in  tins,  which  are  hermetically 
closed,  and  heated  to  a  temperature  of  110°,  so  as 


252          M1CKOBES,   FEKMENTS,  AND  MOULDS. 

to  ensure  the  destruction  of  all  germs.  A  very  small 
aperture  is  left  at  the  top  of  the  case  for  the  escape 
of  steam  and  air,  which  is  closed  with  a  drop  of  solder 
before  the  ebullition  of  the  liquid  within  is  completely 
over. 

The  envelopment  of  meat  in  its  own  fat,  its  pre- 
servation in  sugar,  wax,  etc.,  are  analogous  protective 
processes,  always  employed  at  a  high  temperature. 

When  meat  is  smoked,  the  aromatic  principles  of 
carbolic  acid,  creosote,  etc.,  contained  in  the  smoke, 
destroy  the  ferments  and  prevent  the  subsequent 
development  of  air-germs.  It  is,  therefore,  a  true  anti- 
septic, analogous  to  the  salts  used  to  preserve  meat 
or  fish  by  pickling.  Meat  may  also  be  preserved  by 
desiccation,  when  it  is  cut  in  thin  strips  and  exposed 
to  the  sun  and  air.  This  constitutes  the  jerked  beef 
of  South  America. 

Excellent  results  are  now  obtained  by  drying  meat 
at  from  35°  to  55°  in  a  stove  through  which  a  current 
of  dry  air  is  passed.  The  powdered  meats  to  be  ob- 
tained from  chemists,  which  are  of  great  use  in  nourish- 
ing the  sick  and  convalescent,  are  prepared  by  an 
improvement  on  this  process.  They  are  absolutely 
free  from  smell,  and  will  keep  as  long  as  they  are 
protected  from  damp.  .  Vegetables  cooked  by  steam, 
and  then  compressed  and  dried,  may  be  kept  for 
several  years. 

Eefrigeration  by  ice  has  been  used  to  preserve 
meat.  But  when  congelation  has  occurred  in  the 


MEANS  OF  DEFENCE  AGAINST  MICROBES.      253 

< 

fluids  contained  in  the  muscular  tissue,  putrefaction 
sets  in,  and  rapidly  increases,  as  soon  as  the  tempera- 
ture rises  a  few  degrees  above  freezing-point.  The 
meat  also  acquires  an  unpleasantly  sweet  taste.  It 
will  be  remembered  that  the  first  cargo  of  frozen 
American  meat  which  was  brought  to  Paris  had  con- 
tracted an  unpleasant  taste  and  was  very  soon 
tainted.  When  meat,  game,  or  fish  is  kept  in  ice,  the 
congelation  of  the  fluids  contained  in  their  tissues 
must  therefore  be  avoided. 

Many  antiseptics,  vinegar,  alcohol,  glycerine,  etc., 
may  likewise  be  used  to  preserve  meat  and  other 
alimentary  substances. 

Antiseptics  and  Disinfectants. — We  will  discuss 
the  substances  which  are  thus  designated,  especially 
from  the  hygienic  point  of  view,  and  as  a  preventive 
treatment  of  contagious  diseases,  indicating  the  action 
of  these  substances  on  microbes. 

Antiseptics  have  been  studied  by  Jalan  de  La  Croix 
with  reference  to  their  action  on  microbes  in  general. 
His  experiments  were  performed  on  culture  liquids 
made  of  the  juice  of  cooked  meat,  into  which  he 
introduced  an  equal  number  of  drops  of  the  same 
broth,  which  contained  fully  developed  bacteria.  He 
next  ascertained  the  dose,  in  milligrammes,  of  an 
antiseptic  substance  which  would  suffice  either  to 
arrest  their  multiplication  or  to  destroy  the  microbes, 
and  consequently  to  sterilize  the  liquid. 


254          MICROBES,  FERMENTS,   AND  MOULDS. 

He  analysed  in  this  way  twenty  substances  con- 
sidered to  be  antiseptic,  or  commonly  used  as  such. 
He  has  published  a  table  in  which  these  substances 
are  classified  in  their  order  of  activity,  and  it  includes 
among  others  the  following  antiseptics,  which  we  cite 
in  the  order  assigned  to  them : — 

Corrosive  sublimate  (mercuric  chloride)       ...         ...  No.    1 

Chloride  of  lime  at  98° No.    3 

Sulphurous  acid            No.    4 

Essence  of  mustard       No.    9 

Thymol No.  13 

Salicylic  acid      No.  14 

Carbolic  acid      No.  16 

Boracic  acid        No.  18 

Alcohol No.  19 

Essence  of  eucalyptus No.  20 

The  three  last  substances  are  incapable  of  steri- 
lizing culture  broths. 

This  table  shows  that  carbolic  acid,  which  is  now 
so  much  in  use,  does  not  destroy  microbes  so  efficiently 
as  salicylic  acid,  permanganate  of  potassium,  thymol, 
benzoic  acid,  bromides,  and  iodine.  In  this  estimate, 
however,  we  must  take  into  account  how  far  the  use 
of  each  antiseptic  is  practicable. 

Thus,  corrosive  sublimate,  which  these  experiments 
show  to  be  the  best  antiseptic,  can  be  used  as  an 
external  lotion,  but  it  cannot  be  given  internally  in 
doses  sufficient  to  produce  the  desired  effect.  Eighty 
milligrammes  are  required  to  sterilize  a  litre  of  broth, 
and  forty  to  arrest  the  development  of  bacteria. 
Twenty  milligrammes  will  not  effect  this  result,  and 


MEANS  OF  DEFENCE  AGAINST  MICROBES.     255 

this  latter  dose  is  a  maximum  which  it  is  almost 
impossible  to  exceed  in  man  in  the  course  of  twenty- 
four  hours  without  poisoning  him. 

Sulphurous  acid  is  very  effectual  when  employed 
in  fumigations,  but  it  does  not  penetrate  to  the  interior 
of  the  tissues,  and  only  acts  on  the  microbes  on  their 
surface.  It  does  not  destroy  their  spores. 

Iodine  has  great  effect  in  this  respect.  Davaine 
has  ascertained  that  seven  milligrammes  of  iodine 
suffice  to  destroy  the  bacteria  of  anthrax  in  a  litre 
of  liquid.  Instead  of  a  hot  iron,  tincture  of  iodine 
might,  therefore,  be  used  to  cauterize  the  bites  of 
poisonous  flies,  carbuncles,  and  the  pustule  of  anthrax. 

Koch  states  that  a  solution  of  five  per  cent,  of 
carbolic  acid  is  required  to  destroy  the  spores  of 
anthrax  in  twenty-four  hours ;  but  the  bacilli  them- 
selves are  destroyed  by  a  solution  of  one  per  cent. 
A  solution  of  0  02  per  cent,  iodine,  or  0'07  per  cent, 
of  bromine  prevents  the  development  of  bacilli. 

Chloride  of  zinc  and  sulphate  of  iron,  which  have 
been  recommended  as  disinfectants,  are  very  inferior 
to  chloride  of  lime,  which  takes  the  third  place  in  the 
list,  the  second  being  occupied  by  chlorine. 

Alcohol  arrests  the  development  of  bacteria  and 
their  spores,  but  does  not  destroy  the  latter,  even 
at  the  end  of  a  month,  as  it  is  stated  by  Claude 
Bernard. 

Babes  regards  essence  of  mustard  as  an  excellent 
preservative  from  cholera.  If  a  drop  of  this  essence 


256          MICEOBES,  FERMENTS,  AND  MOULDS. 

is  put  at  the  bottom  of  a  bell-glass  which  covers  a 
culture  of  comma  bacilli,  it  arrests  their  development 
and  destroys  them  within  forty-eight  hours. 

When  cholera  is  epidemic,  it  has  been  suggested 
that  rum  or  cognac  should  be  taken,  to  which  salicylic 
acid  is  added,  in  the  proportion  of  25  grammes  to  the 
litre.  A  petit  verre,  or  three  teaspoonsful,  of  this  mixture 
may  be  taken  between  meals  in  coffee,  tea,  or  grog. 

Kedard  has  been  recently  occupied  with  the  dis- 
infection of  the  railway-waggons  used  for  the  trans- 
port of  cattle.  He  regards  most  of  the  substances 
employed,  including  sulphurous  acid,  as  insufficient. 
The  only  effectual  process  is  by  steam,  at  a  tempera- 
ture of  110°,  which  may  be  easily  procured  at  the 
railway  stations. 

As  we  have  already  said,  the  oxygen  contained  in 
air  is  an  excellent  antiseptic,  and  the  attempt  has 
been  made  to  employ  it ;  but  the  experiments  of  Bert 
and  Regnard  show  that  bacteria  are  only  destroyed 
by  oxygen  at  a  high  pressure.  As  for  oxygenated 
water,  it  has  not  yet  afforded  the  results  which  were 
expected  from  it. 

Finally,  each  species  of  microbe  appears  to  be 
more  or  less  sensitive  to  the  action  of  different 
therapeutic  agents.  Thus  the  effect  of  mercurial  salts 
on  the  microbe  of  syphilis  was  known  before  the 
existence  of  the  microbe  itself  was  known ;  that  of 
the  salts  of  quinine  and  arsenic  on  the  microbes  of 
intermittent  fever,  etc. 


MEANS  OF  DEFENCE  AGAINST  MICROBES.     257 

We  must,  in  conclusion,  rely  much  more  upon 
measures  of  hygiene  than  on  antiseptics  to  ward  off 
the  attacks  of  the  microbes  which  are  factors  of 
disease.  Even  in  Lister's  dressing,  it  is  probable 
that  the  hermetic  closing  of  the  wound  has,  as  it  is 
shown  by  Gue"rin's  process,  much  more  effect  than 
carbolic  acid,  which  is  shown  by  direct  experiments 
to  be  a  feeble  and  generally  an  insufficient  antiseptic. 

We  have  still  to  speak  of  the  preventive  vaccina- 
tions and  inoculations  on  which  medicine  relies  more 
than  on  antiseptics;  but  this  subject  will  be  better 
discussed  in  the  ^following  chapter,  when  we  have 
spoken  of  the  processes  of  culture  by  which  the 
liquids  destined  for  these  inoculations  are  prepared. 


258          MICEOBES,  FEBMENTS,  AND  MOULDS. 


CHAPTER  VIL 

LABORATORY  RESEARCH,  AND  CULTURE  OF  MICROBES. 

THE  processes  employed  in  laboratories  for  the  study 
and  culture  of  pathogenic  microbes  are  now  very 
complicated,  and  they  have  attained  a  remarkable 
degree  of  perfection.  In  such  an  elementary  work  as 
this  we  can  only  give  a  general  idea  of  these  different 
processes,  and  for  details  we  must  refer  our  readers  to 
the  valuable  work  by  Cornil  and  Babes,  Les  Bacteries, 
in  which  the  technique  of  laboratories  devoted  to  the 
histology  of  microbes  is  described  with  great  accuracy 
and  clearness. 

Microscopes. — The  best  instruments  for  the  research 
and  study  of  microbes  are  those  of  Zeiss,  Jena,  and 
Ve'rick,  Paris.  Immersion  lenses,  either  for  use  in 
water  or  in  other  homogeneous  liquids,  are  indispen- 
sable for  the  high  magnifying  power  which  is  necessary 
in  order  to  see  most  bacteria  distinctly.  Condensers, 
especially  those  of  Abb4  made  by  Zeiss,  are  no  less 
useful  in  order  to  concentrate  the  luminous  rays  on 
that  point  of  the  preparation  which  is  to  be  specially 
examined,  and  to  place  the  bacteria  in  relief  after 


LABOEATORY  RESEARCH,  ETC.       259 

they  have  been  stained  by  the  process  we  are  about  to 
mention. 

A  preparation  ought  first  to  be  examined  under  a 
low  magnifying  power  (from  50  to  100  diameters),  so 
as  to  study  the  topography  of  the  object,  and  ascertain 
the  points  at  which  the  colonies  of  microbes  may  be 
sought  amid  the  tissues  of  a  section,  or  of  the  matters 
in  suspension  in  the  liquid. 

We  should  then  go  on  to  a  higher  magnifying 
power  (for  example,  to  from  500  to  700  diameters), 
making  use  of  the  simple  light  of  the  mirror ;  and  we 
should  ultimately  come  to  the  highest  magnifying 
powers  (from  1000  to  1500  diameters),  using  immer- 
sion-lenses and  the  condenser. 

Instruments,  Microtome. — The  instruments  for  fine 
dissection  are  those  commonly  used  in  histology.  In 
addition,  needles  of  glass  and  platinum  are  necessary, 
and  thin  spatulas  of  nickel  to  convey  the  sections,  etc. 

The  ordinary  razor,  which  serves  for  hand  sections, 
will  not  do  for  the  thin,  wide  sections  necessary  for 
the  discovery  of  bacteria.  In  this  case  a  microtome 
must  be  used,  an  instrument  for  making  thin  sections, 
for  which  purpose  those  of  Thoma  or  Verick  are  the 
best.  Sometimes  the  object  to  be  examined  is 
hardened  by  freezing  it  with  ether  spray,  since  this 
makes  it  possible  to  cut  thin  sections  by  hand.  This 
is  Jung's  process. 

Non  -  staining  Liquid  Reagents.  —  Acids,  bases, 
alcohol,  oil  of  aniline,  and  other  essences  serve  to 


260          MICROBES,  FERMENTS,  AND  MOULDS. 


dehydrate  and  partially  decolourize  preparations. 
Canada  balsam  is  used  to  mount  them;  and  finally 
distilled  water,  absolutely  free  from  microbes,  which 
may  be  easily  obtained  by  means  of  the  Chamberland 
filter  already  described,  is  used  for  washing  instru- 
ments, etc. 

Mode  of  collecting  the  Liquids  to  be  examined. — In 
order  to  collect  the  liquids  to  be  obtained 
in  the  wards  of  a  hospital  or  elsewhere 
(blood,  urine,  sputum,  stagnant  or  sewer 
water,  etc.),  pipettes,  which  may  be  either 
straight  or  with  twisted  necks,  are  used, 
ending  in  a  capillary  point  closed  by 
heat,  and  in  its  upper  part  by  a  stopper 
of  fine,  sterilized  cotton  wool.  The 
pipette  is  heated  at  a  blowpipe  flame, 
in  order  to  destroy  the  germs.  When  it 
is  to  be  used,  the  point  is  broken  off, 
and  it  is  plunged  into  the  liquid  (dis- 
charge from  a  freshly  opened  abscess, 
blister  of  erysipelas,  etc.),  and  an  aspira- 
tion is  made  through  the  other  end.  The 
liquid  is  unable  to  rise  above  the  level 
of  the  twisted  neck;  and  this  is  important, 
especially  when  the  aspiration  is  made 
by  the  mouth.  The  point  is  then  resealed 
at  the  lamp.  The  shape  of  these  pipettes 
may  be  varied  according  to  the  require- 
ments, so  long  as  the  same  precautions  are  always 
taken  to  avoid  mistakes. 


Fig.  102. —  Small 
pipette  with 
twisted  neck, 
corked  with  cot- 
ton wool  and 
sterilized. 


LABORATORY  RESEARCH,  ETC.       261 

Preparations. — Such  precautions,  and  especially 
the  most  scrupulous  cleanliness,  are  necessary  in 
making  preparations,  since  air,  water,  dust,  the  human 
hand,  and  instruments  may  all  introduce  foreign 
microbes.  The  instruments  should  be  washed  in  abso- 
lute alcohol,  and  it  is  still  more  effectual  to  heat  them 
to  a  temperature  of  from  150°  to  200°. 

As  to  the  liquids  (pus,  mucus,  etc.),  the  upper  sur- 
face should  not  be  taken,  but  that  which  is  nearest  to 
the  tissues,  and  it  should  be  spread  on  a  thin  slide 
by  a  platinum  wire,  which  has  been  heated  red  hot 
and  then  allowed  to  cool. 

When  the  tissues  are  to  be  examined,  part  of  them 
is  detached  by  a  knife  which  has  been  heated  red  hot. 
It  is  placed  in  Jung's  freezing  microtome,  in  order  to 
cut  sections,  after  it  has  been  hardened  in  alcohol,  to 
which  bichromate  of  potassium  is  sometimes  added. 
The  sections  are  made  as  large  as  possible,  and  are 
then  instantly  transferred  to  a  capsule  full  of  alcohol, 
in  which  they  spontaneously  unfold.  The  glass  or 
platinum  needle,  and  the  nickel  or  platinum  spatula, 
serve  to  spread  out  and  smooth  these  sections. 

Staining  Methods. — Aniline  dyes  have  the  property 
of  giving  a  more  vivid  colour  to  the  bacteria  than  to 
the  surrounding  tissues,  often  even  without  destroying 
them  or  altering  their  movements.  This  property  has 
been  turned  to  account,  and  the  staining  of  preparations 
is  now  largely  practised. 

Methyl- violet,  or  fuchsin,  in  aqueous  solution,  serves 


262          MICROBES,  FERMENTS,  AND  MOULDS. 

to  stain  the  living  bacteria  in  a  drop  of  water,  under 
a  cover-glass.  A  small  drop  of  the  staining  liquid  is 
slowly  diffused  into  the  preparation,  and  gradually 
tinges  the  bacteria  without  giving  any  sensible  colour 
to  the  liquid  which  contains  them.  When  the  comma 
bacillus  of  cholera  is  thus  treated,  it  is  still  capable  of 
motion  after  the  lapse  of  twenty-four  hours,  and  it  will 
continue  to  develop  if  the  stage  of  the  microscope  is 
heated  to  25°. 

In  sections  which  have  been  hardened  or  dried  in 
alcohol  the  bacteria  have  ceased  to  live,  but  they  may 
be  stained  with  the  following  reagents — Grenacher's 
borassic  carmine,  hematoxylin,  and  tincture  of  iodine 
may  be  respectively  employed,  according  to  the  species 
of  microbe  which  is  to  be  stained:  Micrococcus,  the 
flagellum  of  bacteria,  Bacillus  amylobacter,  moulds, 
etc. 

Aniline  dyes,  with  an  alkaline  or  acid  basis,  are 
very  numerous  and  varied ;  methyl- violet  and  gentian 
in  oil  of  aniline,  or  in  aqueous  solution,  rosine,  saffronine, 
Bismarck  brown,  purpurine,  etc. 

It  is  often  desired  to  effect  a  double  staining  of  the 
section,  the  tissues,  for  example,  being  stained  red,  and 
the  bacteria  violet,  or  conversely.  Picrocarminate  of 
ammonium  gives  this  effect  by  the  following  process : — 
After  staining  the  preparation  with  methyl-violet,  it 
is  dipped  for  a  moment  in  the  iodide  solution,  and 
washed  in  water  or  weak  alcohol ;  it  is  then  steeped 
for  some  minutes  in  the  picrocarminate,  of  which  the 


LABORATOKY  RESEARCH,  ETC.       263 

colour  is  made  lighter  by  washing  with  absolute 
alcohol  and  oil  of  cloves,  and  the  preparation  is  after- 
wards mounted  in  balsam.  The  nuclei  of  the  cells  are 
then  of  a  carmine  red,  and  the  bacteria  are  violet ;  the 
rest  of  the  preparation  is  of  a  much  paler  colour. 

Ehrlich's  Method. — We  mentioned  this  method 
when  speaking  of  the  bacillus  of  tuberculosis.  It 
consists  in  treating  the  sections  or  mounted  prepara- 
tion with  a  solution  of  methyl-violet  in  aniline  oil,  and 
the  colour  is  afterwards  quickly  discharged  in  nitric 
acid ;  the  bacteria  alone  remain  violet.  Fuchsin, 
methylene  blue,  coccinine,  vesuvine,  etc.,  are  also  em- 
ployed in  various  processes  for  staining  bacteria. 

Measurement,  Drawings,  and  Photoyraplis. — Bac- 
teria are  measured  by  comparing  them  with  the 
divisions  of  the  micro-millimetre  slide  placed  on  the 
stage  of  the  microscope  over  the  preparation.  The 
microbes  may  be  drawn  without  much  difficulty  by 
means  of  the  camera  lucida — at  least,  after  a  little 
practice,  as  their  forms  are  not  at  all  complex.  But 
the  results  afforded  by  photography  are,  as  it  is  plain, 
very  superior.  The  photographic  plate  is  indeed  more 
sensitive  than  the  eye,  and  often  allows  us  to  see 
details  which  had  escaped  the  latter.  Koch  has  given 
good  illustrations  of  pathogenic  bacteria  in  his  book 
entitled,  Beitrdye  zur  Biologie  der  Pflanzen,  voL  ii. 
(1877). 

Methods  of  Microbe  Culture. — The  development  of 
microbes  may  be  observed  by  placing  the  drop  of 


264 


MICEOBES,   FEEMENTS,  AND  MOULDS. 


liquid  to  be  examined  in  Ranvier's  moist  chamber, 
consisting  of  a  glass  holder,  with  a  circular  groove  and 
a  flat  space  in  the  centre.  On  the  top  is  a  cover-glass, 


Fig.  103.— Different  forms  of  culture  flasks  employed  by  Pasteur  (from  Duclaux). 

which  is  bordered  with  paraffin  or  vaseline,  in  order  to 
seal  it.     The  groove  contains  air  and  a  little  liquid. 


LABORATORY  RESEARCH,  ETC. 


265 


The   stage  of  the  microscope   is  maintained  at  the 
requisite  temperature. 

In  order  to  make  cultures  in  large  quantities,  other 
kinds  of  apparatus  are  in  use.  The  liquid  supposed  to 
contain  microbes  is  introduced  into  sterilized  nutritive 
liquids  by  means  of  a  platinum  wire,  which  has  been 
heated  red  hot  and  then  allowed  to  cool;  its  end  is 


Fig.  104. — Gas  stove  for  the  heating  and 
sterilizing  of  flasks. 


Fig.  105.— Pasteur's 
culture  tubes. 


dipped  into  the  liquid,  and  then  instantly  transferred 
to  the  culture,  while  it  is  exposed  to  the  heat  of  a 
spirit-lamp.  The  flask  is  then  sealed  with  a  wad  of 
cotton  wool. 

The  culture  liquids  employed  by  Pasteur  are  the 
extract  of  beer-yeast,  an  infusion  of  hay,  boiled  and 
neutralized  urine,  and  the  broth  of  various  kinds  of 


266          MICROBES,  FEEMENTS,   AND  MOULDS. 

meat.  The  flasks  are  all  modifications  of  the  form 
indicated  in  Fig.  76.  These  flasks  are  heated  in  an 
iron  gas  stove  (Fig.  104),  of  which  the  double  case  is 
heated  by  gasburners,  and  it  contains  a  basket  of  iron 
wire  as  the  receptacle  of  the  flasks,  tubes,  etc.,  which 


Fig.  106. — Stand,  bearing  culture  tubes. 

are  to  be  sterilized.     The  temperature,  regulated  by  a 
thermometer,  must  rise  to  from  1 50°  to  250°. 

The  nutritive  liquid  is  boiled  in  a  porcelain  cru- 
cible in  the  open  air,  and  is  introduced  by  breaking 
off"  the  tapered  end  of  the  flask ;  it  is  then  instantly 
plunged  into  the  broth,  and  drawn  by  an  aspiration 
through  the  opposite  tube,  after  which  the  tapered 
end  is  resealed  at  the  lamp. 


LABOR ATOHY  RESEARCH,   ETC.  267 

The  tubes,  which  have  two  reservoirs  and  two 
tapered  ends  (Figs.  105,  106),  are  very  numerous  in 
Pasteur's  laboratory.  They  are  ranged  on  a  stand  in 
the  way  shown  in  the  figure. 

It  is  ascertained  that  the  contents  of  the  tubes  are 
really  sterilized  by  leaving  them  for  several  days  in 
a  stove  which  is  maintained  at  a  temperature  of  35°. 

In  addition  to  the  culture  liquids  already  indi- 
cated, many  others  consist  of  various  solutions  of 
phosphates  of  lime  and  potassium,  albuminous  solu- 
tions, etc. 

Solid  Nutritive  Substances. — In  order  to  isolate  the 
different  species  of  bacteria,  and  to  obtain  pure  cul- 
tures, solid  substances  are  now  preferred :  eggs,  slices 
of  potatoes  and  carrots, '  but  especially  gelatine  and 
gelose — which  comes  from  Japan  ready  for  use,  and  is 
said  to  be  extracted  from  a  marine  alga — and  the  gela- 
tinized serum  of  the  blood  of  oxen.  All  these  sub- 
stances are  transparent,  so  that  the  cultures  can  be 
easily  observed  in  glass  tubes.  Koch,  in  his  Berlin 
laboratory,  makes  almost  exclusive  use  of  solid  media, 
which  are  first  sterilized  by  similar  precautions. 

In  order  to  obtain  pure  cultures,  all  kinds  of  germs 
are  first  allowed  to  grow ;  then  a  very  small  amount 
of  them  is  taken  from  the  culture  medium,  and 
transferred  to  the  sterilized  medium,  in  which  fewer 
microbes  naturally  appear.  After  several  repetitions 
of  this  transplantation,  sufficiently  pure  cultures  may 
generally  be  obtained  within  a  short  time. 


268          MICKOBES,  FERMENTS,  AND  MOULDS. 

Koch  employs  a  more  certain  method.  He  makes 
his  sowings  on  glass  plates,  covered  with  sterilized 
gelatine  and  kept  at  a  temperature  of  30°,  by  means  of 
a  slender  platinum  wire  which  has  been  made  red  hot, 
then  allowed  to  cool,  and  charged  with  a  very  minute 
particle  of  matter,  which  is  full  of  bacteria.  The 
colonies  of  different  microbes  isolate  themselves,  and 
may  be  plainly  seen  on  the  glass  plate  with  the  aid  of 
a  magnifier.  Their  variable  size  and  characters  often 
enable  experienced  observers  to  distinguish  them  by 
their  aspect  alone  (Fig.  87,  1,  2).  The  test-tubes, 
containing  sterilized  gelatine,  are  then  inoculated 
with  the  microbe  which  it  is  desired  to  study  (Figs. 
82,  105),  after  taking  the  usual  precautions. 

The  niters  used  to  sterilize  liquids  are  of  Sevres 
biscuit-ware  heated  to  120°,  or  unglazed  pottery. 
Such  is  the  Chamberland  filter  already  described. 

Cultures  for  Experiments  on  Animals. — The  pro- 
cesses we  have  just  indicated  are  also  necessary  in 
these  experiments.  Here  likewise  all  the  causes  of 
error  which  would  arise  from  the  want  of  cleanliness,  or 
from  the  impurity  of  the  culture  liquids,  must  be  care- 
fully avoided;  and  it  must  also  be  ascertained  that 
the  effect  produced  on  the  animal  is  not  due  to  any 
other  microbe  than  that  of  the  experiment,  nor  to 
any  irritating  and  septic  substance.  The  experiment 
should  be  repeated  several  times  by  taking  some  of 
the  blood  of  the  inoculated  animal,  and  making  a  pure 
culture,  which  may  be  used  to  reproduce  the  disease 
in  other  animals. 


LABORATORY  RESEARCH,  ETC.       269 

Attenuation  of  Pathogenic  Microbes. — Successive 
cultures  have  established,  as  we  have  seen,  the  pos- 
sibility of  attenuating  virus,  and  transforming  it  into 
vaccine.  The  processes  employed  to  attain  this  object 
are  complex  and  varied,  according  to  the  species  of 
bacterium  with  which  we  have  to  do. 

Thus,  for  fowl-cholera,  Pasteur  found  that  cultures 
dating  from  fifteen  days,  or  from  one,  two,  eight,  and 
ten  months,  progressively  lost  their  virulence,  and  he 
believes  this  attenuation  to  be  due  to  the  action  of  the 
oxygen  of  the  air.  So,  again,  Koch  supposes  that  the 
action  of  the  air  and  the  desiccation  of  the  germs 
produces,  after  a  time,  the  natural  extinction  of  the 
disease. 

Toussiant  and  Chauveau  attenuate  the  virus  of 
anthrax,  as  we  have  seen,  by  subjecting  it  to  a  tem- 
perature of  from  42°  to  43°.  Pasteur  and  Thuillier  have 
attenuated  the  virus  of  swine  fever  by  passing  it 
through  the  system  of  a  rabbit.  Pasteur  has  also 
attenuated  the  virus  of  rabies,  of  which  the  microbe 
is  still  unknown,  by  passing  it  successively  through 
the  systems  of  a  rabbit,  monkey,  etc. 

Finally,  the  same  result  may  be  obtained  by  add- 
ing various  antiseptic  substances  to  culture  liquids, 
and  thus  weakening  the  virulent  action  of  the 
microbe. 

Vaccination  and  Inoculation. — The  attenuated 
virus  or  vaccine  thus  obtained  may  be  used  for  inocu- 
lation in  quantities  which  experience  indicates  to 


270          MICROBES,  FEEMENTS,  AND  MOULDS. 

be  necessary  and  sufficient,  quantities  which  vary 
according  to  circumstances.  In  order  to  vaccinate 
a  sheep  against  anthrax,  the  animal  must  be  held  by 
its  fore  feet  in  a  sitting  position,  so  as  to  present  its 
belly  to  the  operator ;  the  tube  of  a  Pravaz  syringe, 
containing  the  injection,  is  then  inserted  in  the  base 
of  the  groin,  which  is  devoid  of  wool.  In  cattle  the 
operation  is  performed  at  the  root  of  the  tail.  It  is 
performed  twice — first  with  a  weak  vaccine,  and,  after 
the  lapse  of  a  week,  with  one  which  is  stronger. 

Every  one  is  acquainted  with  the  process  of  vacci- 
nating the  human  subject  against  small-pox,  which 
may  be  done  either  with  lymph  from  an  infant  or 
from  a  calf.  A  lancet  or  grooved  needle  is  employed, 
on  which  there  is  a  drop  of  lymph,  and  five  or  six 
punctures  are  made  on  the  arms  or  thighs. 

We  must  not  imagine  that  vaccination  can  become 
an  absolute  preservative  from  all  diseases.  For  in- 
stance, in  erysipelas,  pneumonia,  and  gonorrhoea 
a  first  attack  is  so  far  from  warding  off  a  second 
attack  of  the  same  disease,  that  it  creates  a  favourable 
field  for  relapses.  It  may,  consequently,  be  assumed 
a  priori  that  vaccination  in  such  cases  would  do  more 
harm  than  good  (Cornil).  It  is  the  same  with  inter- 
mittent fever,  tuberculosis,  syphilis,  etc. ;  all  diseases 
by  which  the  same  individual  may  be  attacked  several 
times,  and  at  varying  intervals  of  time — a  clear  proof 
that  the  first  attack  has  created  no  immunity  against 
subsequent  attacks. 


LABOEATORY  RESEARCH,  ETC.       271 

Immunity. — This  term  is  applied  to  the  property 
which  the  organism  may  acquire  of  being  safe  from 
attacks  of  certain  diseases  due  to  microbes,  either  in 
consequence  of  a  former  attack,  or  from  a  condition 
which  doubtless  arises  from  absorbing  the  pathogenic 
poison  in  minute  doses,  often  repeated.  Acclimatization 
frequently  constitutes  immunity.  Thus,  in  countries 
where  malaria,  yellow  fever,  etc.,  prevail,  the  inhabi- 
tants are  less  apt  to  contract  the  disease  than 
strangers.  Such  immunity  is  not  absolute,  and  may 
be  lost  in  course  of  time.  This  has  been  ascertained 
in  the  case  of  small-pox,  so  that  it  is  prudent  to  be 
revaccinated  every  ten  or  twelve  years. 


272          MICROBES,  FEUMENTS,  AND  MOULDS. 


CHAPTER  VIIL 

POLYMORPHISM  OF  MICROBES. 

MICROBES  (bacteria,  ferments,  and  moulds)  display, 
like  all  the  lower  types  of  the  animal  and  vegetable 
kingdoms,  considerable  polymorphism.  It  is  necessary, 
therefore,  that  we  should  be  on  our  guard,  lest  this 
phenomenon  should  be  the  source  of  errors  and  con- 
fusions very  prejudicial  to  science,  either  by  describing 
as  distinct  species  different  forms  of  the  same  species, 
or  by  being,  on  the  other  hand,  led  to  regard  as  one 
and  the  same  species  several  which  are  really  distinct, 
and  which  for  want  of  proper  precautions,  have  been 
brought  together  in  the  same  preparation,  without  the 
observer  being  aware  of  the  fact. 

We  have  indicated  in  the  foregoing  chapter  the 
scrupulous  care  which  is  indispensable  in  laboratories 
in  order  to  guard  against  surprises  of  this  kind. 
These  precautions  are  not  always  sufficient,  and  ex- 
perience shows  that  a  single  act  of  forgetfulness  or 
distraction  on  the  part  of  the  observer  is  enough  to 
spoil  the  result  of  a  long  series  of  researches.  More- 


POLYMORPHISM  OF  MICROBES.  273 

over,  these  precautions  often  afford  only  a  negative 
result,  since  some  bacteria  which  have  been  reproduced 
for  a  long  while  in  the  same  form  in  a  given  medium 
of  culture,  suddenly  change  their  form  and  habits  on 
beinsr  transferred  to  another  medium. 

o 

In  order  to  give  an  idea  of  the  difficulties  which 
beset  this  branch  of  research,  it  will  be  enough  to 
cite  the  history  of  lichens,  a  history  well  known  to  all 
cryptogamous  botanists.  The  structure  of  these  lower 
plants  is  at  once  simple  and  complex,  since  we  may 
regard  them  as  formed  by  the  association,  or  symbiosis, 
as  it  is  technically  called,  in  each  lichen  of  a  species 
of  green  alga  with  a  species  of  colourless  fungus  of  the 
Ascomycetes  group. 

De  Bary  and  the  botanists  of  his  school,  Schwen- 
dener,  Bornet,  Reess,  Stahl,  etc.,  state  that  in  what 
is  called  a  lichen  the  tissues  of  an  alga  and  those  of 
a  fungus  are  intermingled  in  such  a  way  as  to  form 
the  structure  which  constitutes  the  lichen.  Owing 
to  this  close  association,  a  lichen  can  live  like  other 
plants,  not  as  a  parasite,  like  fungi :  the  green  parts 
of  the  alga  assimilate  the  carbon  contained  in  the 
air  in  the  form  of  carbonic  acid,  and  thus  supply 
nutriment  to  the  fungus,  which  is  consequently 
regarded  as  a  sort  of  parasite  to  the  alga.  In  return, 
the  fungus  supplies  its  mycelium  to  the  lichen,  by 
which  the  latter  is  enabled  to  fasten  on  the  surface  of 
rocks  or  trees. 

This  attractive  theory  was  in  favour  for  a  con- 
13 


274          MICROBES,   FERMENTS,  AND  MOULDS. 

siderable  time.  It  is  now  almost  completely  abandoned, 
and  recent  researches,  made  with  the  view  of  isolating 
the  alga  and  fungus  which  were  supposed  to  co-exist 
in  the  lichen,  tend  more  and  more  to  show  that  the 
lichen  is  an  independent  plant,  and  not  merely  an 
association  of  two  plants  of  distinct  families,  algae  and 
fungi. 

Errors  of  the  same  kind  may  occur  in  the  study 
of  microbes,  which,  from  their  minute  size,  their 
unicellular  nature,  the  rapidity  of  their  growth,  the 
variety  of  their  habitat,  and  the  great  resemblance 
of  their  form,  are  still  more  difficult  to  distinguish 
than  lichens.  Of  this  we  will  give  some  examples. 

Polymorphism  of  Leptothrix  buccalis. —  Robin 
(1866-1873),  after  studying  the  development  of 
Leptothrix,  stated  that  this  microbe  first  appears  in 
the  form  of  a  micrococcus ;  then  of  a  moving  bacterium, 
resembling  B.  termo,  B.  lineolum,  etc.,  and  finally  it 
forms  the  long  immovable  rod  (bacillus),  which  consti- 
tutes Leptothrix  buccalis.  This  mode  of  evolution, 
supposed  to  be  usual  in  the  genera  Bacillus  and 
Leptothrix,  is  probably  exact,  and,  with  some  reserve 
as  to  the  specific  identity  of  the  different  forms 
observed  by  Robin,  modern  micrographists  are  dis- 
posed to  accept  it.  But  Robin  goes  further:  he 
regards  the  anthrax  bacillus  as  specifically  identical 
with  Leptothrix  buccalis.  The  recent  progress  of 
science  no  longer  permits  us  to  allow  this  identity. 
We  have  seen  that  there  are,  at  any  rate,  two 


POLYMORPHISM  OF  MICROBES.  275 

species,  quite  distinct  in  their  action  upon  men  and 
animals. 

Polymorphism  of  Moulds. — The  comparatively 
early  researches  of  Hallier  and  others  tend  to  show 
that  the  fungi  of  moulds  display  considerable  poly- 
morphism, so  as  to  completely  overthrow  the  classi- 
fication of  these  cryptogams.  These  researches  have 
been  recently  resumed  by  Cocardas,  who  considers 
it  proved  that  all  the  moulds  found  in  saccharine 
liquids  which  have  been  allowed  to  ferment  and  in 
pharmaceutical  extracts  belong  to  one  and  the  same 
species,  which  is  highly  polymorphic,  and  which  he 
terms  the  Penicillium  ferment.  Cocardas  asserts  that 
he  has  seen  this  Penicillium  ferment  pass  through 
the  following  successive  stages  : — Corpuscular  (Micro- 
coccus),  bacteridian  (Bacterium,  Bacillus),  zooglairian 
(colonies,  or  zoogloea),  submerged  hyphse  (torula, 
chaplets,  or  chains),  fructiferous  filaments  (endogenous 
spores),  the  whole  constituting  the  algous  phase  of  the 
cryptogam  which  floats  on  the  surface  of  syrup. 

The  fungoid  phase  then  begins.  The  swellings 
formed  on  the  surface  of  the  liquid  by  the  endogenous 
spores  bud  ;  these  buds  become  elongated,  partitioned, 
and  ramified,  constituting  the  aerial  mycelium  on 
which  the  aerial  fructifications  are  developed,  which 
can  only  form  outside  the  liquid. 

These  fructifications,  although  all  issuing  from  the 
same  mycelium,  may  present  either  the  form  of  asper- 
gillus,  of  mucor,  or  of  penicillium,  according  to  the 


276          MICROBES,   FERMENTS,   AND  MOULDS. 

nature  of  the  spores  on  the  fructiferous  hypha.  In 
other  words,  the  characters  which  have  been  hitherto 
considered  as  proper  to  the  three  genera,  Aspergillus, 
Mucor,  and  Penicillium,  themselves  types  of  three 
very  distinct  families,  are  found  either  simultaneously, 


Fig.  107. — The  penicillium  ferment  (Cocardas).  Aerial  fructification  in  extract  of 
liquorice :  the  three  forms,  Mucor  (1),  PeniciUium  (2),  Aspergillus  (3;,  borne  by 
a  single  hypha  A  (x  225  diam.). 

or  successively,  on  the  same  hypha,  and  are  only 
varied  forms  of  a  highly  polymorphic  species,  the 
penicillium  ferment  (Cocardas). 

Fig.  107  represents  the  three  forms  of  fructifica- 


POLYMORPHISM  OF  MICROBES.  277 

tion,  as  Cocardas  states  that  he  has  seen  them,  united 
and  borne  by  a  single  hypha,  magnified  225  diameters. 

Each  form  of  Penicillium  belongs  to  a  special 
change  in  the  syrup.  In  syrup  which  has  become 
turbid,  the  ferment  is  in  the  corpuscular  or  bac- 
teridian  stage;  when  the  syrup  is  ropy,  it  is  in  the 
zooglairian  or  filamentous  stage ;  when  it  has  turned 
sour,  it  is  in  the  stage  of  aquatic  fructification  ; 
finally,  when  the  syrup  is  mouldy,  it  is  in  the  stage 
of  aerial  fructification. 

Cocardas  states  that  he  has  observed  this  really 
astonishing  polymorphism  while  making  use  of  the 
ordinary  precautions  for  averting  gross  errors.  Not- 
withstanding facts  of  the  same  kind,  which  have  been 
put  forward  previously,  notably  by  Hallier,  but  which 
are  frequently  contradicted  by  more  accurate  research, 
it  may  be  asked  whether  this  is  not  merely  a  pheno- 
menon of  confusion,  analogous  to  that  which  was 
rightly  or  wrongly  supposed  to  exist  in  the  case  of 
lichens.  Fresh  researches,  made  with  greater  pre- 
cision in  sterilized  liquids,  and  accompanied  by  the 
most  scrupulous  precautions,  are  necessary  before 
these  facts  can  be  definitively  accepted  by  science. 

Polymorphism  of  Fungi  of  the  Human  Skin. — It 
is  more  easy  to  accept,  at  any  rate  in  part,  the  poly- 
morphism recently  noted  by  Grawitz  in  the  fungus 
of  Favus  (ringworm),  which  we  have  already  de- 
scribed under  the  name  of  Achorion  Schoenlenii. 

Grawitz  asserts  that  Achorion  Schoelenii  of  ring- 


278          MICROBES,   FERMENTS,  AND  MOULDS. 

worm,  Trichopkyton  tonsurans  of  cirinnate  herpes,  and 
Microsporon  furfur  of  variegated  pityriasis,  are  only 
different  forms  of  one  and  the  same  parasite,  of  which 
he  has  made  a  successful  culture  on  gelatine,  repro- 
ducing its  successive  appearances. 

Grawitz,  however,  goes  further  than  many  micro- 
graphists  will  consent  to  follow  him.  He  asserts  that 
all  the  fungi  of  the  human  skin  are  only  trans- 
planted forms,  modified  by  the  medium,  of  Oidium 
lactis,  the  white  mould  found  on  milk,  bread,  paste, 
potatoes,  etc. 

So,  again,  Oidium  albicans,  the  fungus  of  thrush, 
is,  as  we  have  said,  specifically  identical  with  Sac- 
charomyces  mycoderma,  or  flowers  of  wine,  a  ferment 
which  is  developed  on  the  surface  of  liquids  which 
are  acid  and  contain  little  sugar.  This  must  not  be 
confounded  with  Mycoderma  aceti,  a  true  bacterium, 
causing  the  acid  fermentation  of  wine  and  beer. 

Still  more  recently,  in  1883,  Malcolm  Morris  and 
G.  C.  Henderson  have  stated  that  in  an  artificial 
culture  of  peptonized  gelatine  at  the  temperature  of 
from  15°  to  20°,  spores  of  Trichophyton  tonsurans  were 
developed,  forming  ramified  hyphge  which  were  after- 
wards covered  with  fructifications  resembling  those  of 
Penicillium. 

Injections  of  Mould-spores  into  the  Blood. — Grawitz 
injected  spores  of  Penicillium  and  Aspergillus  into 
the  vascular  system  of  rabbits,  with  the  view  of 
demonstrating  their  transformation  into  bacteria.  He 


POLYMORPHISM  OF  MICROBES.  279 

thus  obtained  the  formation  of  small  metastatic 
centres  in  the  kidneys,  liver,  lungs,  etc.  The  spores 
sent  forth  hyphae  which  were  able  to  produce  im- 
perfect organs  of  fructification,  but  failed  to  effect 
the  formation  of  fresh  spores.  Gaffky,  Koch,  and 
Leber  repeated  these  experiments,  and  showed  that 
the  acclimatization  of  any  kind  of  mould  in  the 
interior  of  the  system  was  impossible,  whatever  might 
be  the  more  or  less  serious  lesions  produced  by  the 
introduction  of  foreign  bodies  into  the  blood  of  a 
warm-blooded  animal. 

Errors  caused  in  Laboratory  Experiments  by  the 
Involuntary  Mixture  of  Different  Microbes. — We 
should  be  the  more  cautious  about  accepting  the  real 
or  apparent  polymorphism  of  certain  microbes,  since 
the  most  scrupulous  precautions  do  not  always  suc- 
ceed in  preventing  confusion.  Of  this  Klein  gives 
the  following  instances. 

While  he  was  studying  the  microbe  of  anthrax  in 
his  laboratory  at  the  Brown  Institution,  one  of  his 
friends  was  studying  canine  distemper  in  an  adjoining 
room.  This  friend  injected  the  blood  of  a  dog  affected 
by  distemper  into  a  guinea-pig's  veins,  and  was  sur- 
prised to  see  the  animal  die  two  days  later  with  all 
the  symptoms  of  anthrax,  and  to  discover  Bacillus 
anthracis  in  its  blood.  Yet  he  had  made  the  injec- 
tion with  a  perfectly  new  hypodermic  syringe ;  while 
Klein,  for  his  own  injections,  had  made  exclusive  use 
of  pipettes  drawn  to  a  point  in  the  flame  of  a  lamp. 


2 SO          MICEOBES,   FEEMENTS,   AND  MOULDS. 

In  this  case,  it  must  be  assumed  that  the  bacilli  and 
spores  of  anthrax  had  settled  on  Klein's  clothes,  had 
spread  to  the  table  and  floor  of  the  second  cabinet, 
and  had  passed  thence  on  to  the  guinea-pig's  hair 
at  the  moment  of  the  experiment. 

Another  operator,  who  inoculated  a  guinea-pig 
with  human  tubercles,  worked  at  the  same  table  as 
that  on  which  Klein  performed  his  experiments  on 
anthrax.  Two  of  the  guinea-pigs  died  with  Bacillus 
anthracis  in  the  blood.  Yet  the  pipettes  in  use  had 
always  been  repointed  in  the  fire,  and  all  the  other 
instruments  had  been  thoroughly  heated  before  the 
inoculation. 

In  another  case,  on  the  contrary,  a  guinea-pig 
inoculated  with  an  attenuated  culture  of  Bacillus 
anthracis,  of  which  the  effect  could  not  be  fatal,  was 
examined  at  the  end  of  some  weeks,  and  all  its  organs 
were  found  to  be  affected  by  the  bacilli  of  tuberculosis. 
On  consulting  his  notes,  Klein  found  that  on  the  same 
day  he  had  performed  experiments  on  tubercular 
matter  in  the  same  laboratory,  but  he  had  always 
been  careful  to  use  different  instruments.  The  same 
phenomenon  was  produced  in  a  rabbit  which  died,  not 
of  anthrax,  with  which  he  was  supposed  to  have  been 
inoculated,  but  of  general  tuberculosis.  The  inocu- 
lating liquid  had  clearly  been  impure. 

It  is  probable  that  Buchner's  experiments  on  the 
bacillus  of  meat  were  vitiated  by  a  similar  error. 
Biichner  inoculated  mice  with  this  bacillus,  and  believed 


POLYMORPHISM  OF  MICROBES.  281 

that  he  had  produced  anthrax.  But  as  he  had  per- 
formed numerous  experiments  on  anthrax  in  the  same 
laboratory,  it  is  probable  that  his  cultures  of  the  meat 
bacillus  were  impure,  and  that  he  had  really  inoculated 
with  B.  anthracis.  The  transformation  of  the  bacillus 
of  meat  into  that  of  anthrax  is  therefore  not  yet 
proved. 

Jequirity  Microbe. — This  is  another  instance  of  an 
analogous  mistake,  owing  to  which  the  Jequirity 
bacillus  has  been  supposed  to  be  transformed  from  a 
merely  septic  into  a  pathogenic  microbe.  This  sub- 
stance, recently  imported  from  India,  is  extracted  from 
the  seeds  of  Abrus  precatorius,  one  of  the  leguminous 
plants.  A  few  drops  of  the  infusion  of  these  seeds 
applied  to  the  eye  produce  conjunctivitis,  which  is 
artificially  excited  in  order  to  effect  the  disappearance 
of  the  granules  (trachoma)  by  which  the  inner  surface 
of  the  eyelids  is  sometimes  affected.  In  India,  the 
same  liquid  is  used  to  kill  cattle  by  a  simple  puncture, 
with  the  object  of  skinning  them. 

When  Sattler  noticed  that  an  infusion  of  Jequirity 
became  full  of  moving  bacilli  in  a  few  hours,  re- 
sembling bacillus  subtilis  of  an  infusion  of  hay  (Fig. 
80),  he  made  cultures  of  this  bacillus,  and  produced 
by  their  means  serious  ophthalmia  in  the  eyes  of 
rabbits.  At  the  same  time  he  ascertained  that  this 
microbe  was  harmless  when  floating  in  the  air,  and 
that  its  pathogenic  properties  were  only  displayed 
when  it  was  cultivated  in  an  infusion  of  Jequirity. 


282          MICKOBES,   FERMENTS,   AND  MOULDS. 

In  spite  of  this,  Sattler  ascribes  the  pathogenic  action 
of  this  substance  to  the  microbe. 

Klein  repeated  his  experiments  'with  great  care, 
and  was  successful  in  solving  the  contradictions  which 
appeared  to  result  from  Sattler's  researches.  He 
proved  that  the  bacillus  of  jequirity,  taken  by  itself, 
could  no  more  produce  an  infectious  ophthalmia  than 
Biichner's  meat  bacillus  could  produce  anthrax.  The 
poisonous  principle  of  jequirity  is  a  chemical  ferment 
(Abrine),  analogous  to  pepsine,  and  independent  of 
any  microbe,  and  its  assumed  bacillus  probably  does 
not  differ  specifically  from  Bacillus  subtilis. 

The  transformation  of  an  originally  harmless  mi- 
crobe into  a  pathogenic  microbe  is  therefore  not  yet 
proved,  and  all  known  facts  contradict  the  possibility 
of  such  a  transformation. 

Septic  and  Pathogenic  Microbes. — Hence  we  are 
led  to  define,  more  precisely  than  before,  the  terms 
septic  microbes  and  pathogenic  microbes,  which  are 
in  current  use  in  bacteriology. 

The  |term  "  septic  "  is  applied  to  the  microbes  or 
bacteria  which  generally  live  in  decomposing  organic 
matter  and  in  dead  bodies.  These  microbes,  or  their 
spores,  are  found  in  the  air,  in  water,  or  the  soil,  in 
the  mouth  and  intestinal  canal  of  a  healthy  man  or 
animal;  but  they  are  developed  in  greater  numbers 
when  the  tissues  are  dead  or  in  a  diseased  condition, 
and  also  in  pus,  in  the  bronchial  secretion  of  pulmonary 
catarrh,  on  the  surface  of  intestinal  ulceration,  etc. 


POLYMORPHISM  OF  MICROBES.  283 

Such  are  Bacterium  teivmo  and  Bacillus  subtilis,  the 
microbes  of  putrefaction,  those  of  the  sweat  of  feet, 
etc.,  of  which  we  have  spoken  above ;  such,  again,  is 
the  bacillus  of  Biichner's  meat  infusion,  that  of  Battler's 
jequirity,  and  finally,  Grawitz's  AspergiUus,  mentioned 
in  this  chapter. 

These  various  microbes,  inoculated  or  injected  into 
blood,  may  indeed  produce  different  disorders,  which 
in  some  cases  always  remain  local  (oedema) ;  in  others 
are  limited  to  metastatic  centres  encysted  in  various 
organs — the  liver,  kidneys,  lungs,  etc. ;  or,  again,  they 
may  produce  a  general  infection  of  the  blood,  as  in  the 
septicernia  produced  by  Davaine  when  he  inoculated 
rabbits  with  the  fluid  of  putrid  beef.  These  rabbits 
died  within  two  days,  and  their  blood  was  found  to 
be  full  of  Bacterium  termo.  The  same  result  has  been 
obtained  by  Pasteur  and  Koch,  by  merely  inoculating 
guinea-pigs  and  mice  with  a  little  putrid  earth  or 
water,  in  which  the  same  organism  was  evidently 
present.  But  in  no  case  a  disease  with  distinct  cha- 
racters was  produced  by  this  means,  with  special 
.symptoms,  epidemic  or  contagious,  analogous  to  those 
of  erysipelas,  anthrax,  tuberculosis,  or  cholera.  Hence 
the  name  of  experimental  septicemia,  since  these 
diseases  do  not  exist  in  nature. 

On  the  other  hand,  those  microbes  are  termed 
pathogenic  which  always  characterize  by  their 
presence  a  special  disease,  epidemic  or  contagious,  and 
possessing  special  symptoms  and  lesions,  whether  this 


284          MICROBES,   FERMENTS,   AND  MOULDS. 

microbe  subsists  in  the  blood,  the  inner  part  of  the 
organs,  or  merely  on  the  surface  of  the  digestive  canal. 
Such  are  the  microbes  of  anthrax,  of  tuberculosis,  and 
of  cholera,  natural  diseases  which  are  not  produced  by 
the  experiments  of  man.  Up  to  this  time  a  septic 
microbe  has  not  been  proved  to  be  transformed  into  a 
truly  pathogenic  microbe,  and  consequently  a  com- 
pletely new  disease,  characterized  by  the  development 
of  this  microbe  in  the  body  of  man  or  animals,  has 
not  been  created. 

It  must  also  be  remarked — and  this  peculiarity  is 
common  to  both  classes  of  microbes — that  certain 
bacteria  produce  very  different  effects,  according  to 
the  animals  into  whose  bodies  they  are  introduced. 
Thus  guinea-pigs  cannot  be  inoculated  with  the 
experimental  septicemia  of  rabbits  and  mice ;  and 
dogs  and  swine  display  more  or  less  resistance  to  the 
inoculation  of  anthrax.  Finally,  there  are  cases  in 
which  the  attempt  to  inoculate  an  animal  with  a 
contagious  disease  merely  produces  a  septicemia 
which  must  not  be  confounded  with  it.  This  result 
will  not  astonish  those  who  know  that  some  species 
of  plants,  poisonous  to  man,  can  be  eaten  with  im- 
punity by  many  animals.  But  it  is  well  to  keep 
this  fact  in  mind  in  laboratories,  when  the  attempt 
is  made  to  inoculate  animals  of  various  species. 


CHAPTER  IX. 

CONCLUSION. 

THE  MICROBIAN  THEORY  COMPARED  WITH  OTHER 
THEORIES  PUT  FORWARD  TO  EXPLAIN  THE 
ORIGIN  OF  CONTAGIOUS  DISEASES. 

THE  parasitic  theory  of  diseases  is  far  from  being 
generally  adopted  by  medical  men  ;  at  this  very  time 
the  theory  is  actively  opposed  by  medical  practitioners 
of  high  standing,  who  are  advocates  of  the  theory  of 
the  innate  character  of  diseases.  In  their  opinion,  the 
disease  is  spontaneously  developed  in  the  patient,  or, 
at  any  rate,  under  the  influence  of  a  contagion  of 
which  the  nature  is  still  unknown.  They  consider  that 
it  is  only  a  secondary  complication  when  microbes  are 
found  in  the  blood,  and  that  these  microbes  are  not 
the  cause  of  the  disease,  nor  even  the  contagious 
element,  nor  the  vehicle  of  contagion.  In  a  word, 
the  microbian  theory  is  in  their  eyes  a  purely  gratuitous 
hypothesis. 

Admitting  with  them  that  the  microbian  theory  is 


286          MICROBES,   FERMENTS,   AND  MOULDS. 

only  an  hypothesis,  let  us  compare  it  with  other  hypo- 
theses which  have  been  proposed  to  explain  the 
virulent  and  contagious  nature  of  certain  diseases. 
This  comparison  may  throw  some  light  on  the  question 
at  issue. 

The  value  of  an  hypothesis  must  be  estimated  by 
the  number  and  importance  of  the  facts  of  which  it 
affords  a  clear,  precise,  and  really  scientific  explanation ; 
it  must  also  be  estimated  by  its  influence  on  the 
advance  of  science.  We  will  therefore  enumerate  the 
principal  theories  which  have  been  proposed  to  explain 
the  origin  of  virulent  and  contagious  diseases,  without 
the  intervention  of  microbes. 

Robins  Theory  of  Blastema. — Although,  as  far  as 
we  are  aware,  Robin  has  not  recently  published  any- 
thing with  reference  to  his  opinion  of  the  value  of  the 
microbian  theory,  some  of  his  pupils  have  set  forth  the 
theory  of  blastema  as  it  was  stated  by  their  master  in 
books  published  from  ten  to  twenty  years  ago. 

In  Robin's  opinion,  no  cell  is  born  from  another 
cell,  in  the  form  of  a  bud,  an  egg,  or  a  spore.  Un- 
doubtedly there  is  no  spontaneous  generation,  at  the 
expense  of  elements  of  exclusively  inorganic  origin ; 
but  this  generation  or  genesis  occurs  every  day  at  the 
expense  of  an  organized  substance  which  is  living, 
but  fluid  and  amorphous,  and  which  has  its  source 
from  other  pre-existent  cells.  This  fluid  is  termed 
blastema  by  Robin.  Blastema  is  the  surplus  of  the 
nutritive  substance,  organized  by  the  cells  and  exuded 


CONCLUSION.  287 

from  them.  New  cells  may  be  completely  formed  at 
the  expense  of  this  blastema,  without  having  their 
source  in  one  cell  more  than  in  another.  According 
to  Robin's  theory,  the  pus-corpuscles,  which  are  a  new 
creation,  are  produced  in  this  way :  they  result  from 
the  exudation  of  a  fluid  which  issues  from  all  the 
organs,  and  are  not  produced  by  the  enlargement, 
reproduction,  and  budding  of  pre-existent  cells,  as  it 
is  stated  in  other  theories,  and  notably  in  those  of 
Schiff  and  Cohnheim. 

When  this  is  established,  it  follows  that  all  diseases 
have  their  origin  in  a  chemical  or  physiological 
change  in  the  blastema,  which  at  one  time  produces 
normal  cells,  adapted  to  replace  those  which  die  from 
natural  decay,  and  at  another  engenders  diseased  cells, 
which  are  dangerous,  either  owing  to  their  too  great 
number,  as  in  septicemia,  or  from  their  peculiar  nature, 
as  in  tubercle  and  cancer.  Here  we  will  quote  Robin's 
words  :  "  The  cause  of  morbid  disturbance  arises  from 
the  changes  which  take  place  in  the  quantity  and 
nature  of  the  immediate  constituents  of  the  actual 
substance  of  the  tissues  and  secretions.  These  changes 
make  the  development  of  minute  spores  possible.  The 
multiplication  of  microscopic  plants  is  a  secondary 
phenomenon;  not  the  scientific  cause  which  actually 
determines  it.  The  presence  of  the  vegetable  parasite 
is  a  complication  which  has  been  mistaken  for  the 
cause "  (Histoire  naturelle  des  vegetaux  parasites  de 
rhommc,  1853,  p.  287). 


288          MICROBES,   FERMENTS,  AND  MOULDS. 

These  words  were  written  more  than  thirty  years 
ago,  and  it  may  be  asked  whether  the  immense  pro- 
gress which  science  has  made  since  that  date  has  not 
somewhat  modified  the  author's  opinions.  Jousset 
de  Bellesme  is  scarcely  entitled  to  take  these  words 
and  paraphrase  them  as  follows : — "  The  microbe, 
where  it  really  exists,  is  only  a  secondary  phe- 
nomenon, and  it  would  not  be  too  much  to  say  that 
no  fresh  element  has  intervened,  either  in  small-pox, 
scarlatina,  or  tubercular  disease ;  in  such  cases  there 
is  only  an  exaggeration  and  reproduction  of  normal 
elements,  which,  influenced  by  wholly  obscure  con- 
ditions, are  evolved  in  an  altogether  unusual  manner." 

The  definition  given  by  Jousset  de  Bellesme  is  not 
that  of  contagious  diseases,  but  of  those  which  are 
combined  under  the  generic  name  of  cancer.  If  he 
means  to  compare  these  diseases  with  cancer,  such  a 
comparison  is  impossible.  It  is  well  known  that 
cancer  is  not  contagious,  and  this  fact  alone  places  a 
gulf  between  these  two  kinds  of  disease.  Cancer  is 
not  only  not  contagious  nor  is  it  conveyed  by  inocula- 
tion, but  it  is  only  hereditary  in  about  a  tithe  of 
cases.  Tuberculosis  is,  on  the  other  hand,  a  con- 
tagious disease,  because  it  is  produced  by  microbes, 
and  it  may  be  set  down  as  hereditary  in  nine  cases 
out  of  ten. 

Jousset  de  Bellesme's  theory,  therefore,  explains 
nothing,  and  leaves  the  question  absolutely  untouched, 
since  it  throws  no  light  on  contagion  and  virulence, 


CONCLUSION.  289 

the  precise  points  which  it  is  essential  to  explain. 
But  we  must  return  to  Robin's  theory.  When  he 
states  that  the  microbe  is  only  developed  in  tissues 
which  are  already  changed,  Robin  is  not  so  far  from 
the  parasitic  theory  as  his  pupils  represent  him  to 
be.  It  matters  little  that  the  microbe  may  be  only 
a  complication,  a  secondary  phenomenon,  if  this 
secondary  phenomenon  dominates  the  whole  disease 
and  invests  it  with  its  dangerous  character,  its  con- 
tagious and  virulent  nature.  In  the  case  of  a  viper's 
bite,  it  is  not  the  bite  from  the  animal's  teeth  which 
is  dangerous,  but  the  introduction  of  the  venom 
which  flows  from  them;  that  is,  the  secondary 
phenomenon.  And  it  is  the  same  with  an  anatomical 
puncture. 

Two  men  in  similar  circumstances  are  attacked  by 
pneumonia;  the  first  will  recover  with  ease  because 
he  is  only  thirty  years  old,  while  the  other  is  almost 
certain  to  die  because  he  is  seventy-five,  but  we  should 
not  therefore  say  that  he  died  of  old  age,  and  that  the 
pneumonia  was  only  a  secondary  phenomenon. 

Oidium  and  the  phylloxera  have  attacked  the 
French  vineyards  which  are  exhausted  by  excessive 
cultivation,  but  it  will  not  therefore  be  denied  that 
these  are  two  dangerous  diseases ;  nor  should  we  say 
that  they  are  secondaiy  phenomena.  It  is  therefore 
evident  that  Robin's  theory,  as  it  is  set  forth  by 
his  disciples,  who  have  resuscitated  statements  made 
twenty  or  thirty  years  ago,  is  no  longer  on  a  level 


290          MICROBES,  FERMENTS,  AND  MOULDS. 

with  the  present  state  of  science,  and  is  in  no  case 
applicable  to  virulent  and  contagious  diseases. 

Theory  of  Charlton  Bastian,  and  the  English  Fol- 
lowers of  his  School. — This  theory,  held  by  the  most 
ardent  opponents  of  the  school  of  Tyndall  and  Pasteur, 
is  set  forth  in  the  writings  of  Lewis  and  Lionel  Beale. 
It  scarcely  differs  from  the  one  we  have  just  stated. 
Lewis  thinks  it  very  evident  that  the  presence  of 
microphyta  of  the  blood  is  only  a  secondary  pheno- 
menon ;  that  the  change  in  the  fluids  of  the  body  is 
effected  before  the  slightest  trace  of  their  presence  can 
be  discovered.  This  is  plainly  Robin's  theory.* 

Beale  is  still  more  absolute  and  exclusive.!  He 
holds  that  the  solid  particles  of  vaccine  are  not  bacteria 
nor  micrococci,  but  bioplasts,  or  formulated  elements 
which  have  their  source  in  the  living  substance  of  the 
cow,  and  these  bioplasts  constitute  the  effective  con- 
tagion of  all  virulent  diseases.  Bioplasts  are  extremely 
minute  particles  of  the  living  substance  of  the  species 
affected  by  the  disease.  The  contagion  is  a  bioplasma, 
and  each  species  of  contagious  bioplasma  manifests  its 
peculiar  specific  action,  and  that  only.  We  must 
leave  it  to  others  to  admire  and  paraphrase  this  scien- 
tific jargon,  which  seems  intended  to  take  us  several 
ages  back.  We  must,  however,  observe  that  Beale's 
theory  is  somewhat  allied  to  another,  much  more 
serious  and  complete,  of  which  we  have  now  to  speak. 

*  Les  Microphytes  du  Sang,  1881. 
f  The  Microscope  in  Medicine,  1882. 


CONCLUSION.  291 

Bechamp's  Theory  of  Microzyma. — According  to 
this  theory,  diseases  are  not  due  to  a  fluid  blastema 
which  is  changed  in  disease,  but  to  an  organized  and 
solid  blastema,  resembling  the  constituents  of  the 
blood,  and  consisting  of  very  minute  particles  of  living 
matter,  which  are  microzyma.  These  are  the  elemen- 
tary granules  which  may  be  seen  under  the  microscope 
in  the  cells  and  in  all  the  fluids  of  the  organism. 
The  mycrozyma,  and  not  the  cells  in  which  they  are 
encysted,  are  the  real  agents  of  all  the  functions  of 
the  organism.  By  the  secretion  of  a  fluid  termed 
zymase,  or  ferment,  by  which  they  are  constantly 
surrounded  (both  together  constituting  what  is  called 
protoplasm) ;  these  microzyma  effect  the  various  trans- 
formations which  have  for  their  final  object  the  nutri- 
tion of  the  organism.  Virulent  and  contagious  diseases 
are  not  produced  by  parasites  coming  from  without, 
but  by  the  microzyma  themselves,  owing  to  a  perver- 
sion of  their  normal  functions.  In  such  cases  they 
secrete  a  vitiated  zymase,  and  are  transformed  into 
micrococci  and  bacteria,  which  it  is  an  error  to  regard 
as  foreign  bodies,  since  they  are  only  the  result  of  the 
special  form  of  microzyma  pre-existing  in  our  tissues. 

It  must  also  be  said  that  these  microzyma  are  im- 
perishable. The  cells  of  our  organism  die  and  are 
renewed,  but  the  microzyma  which  they  contain  are 
only  associated  with  other  microzyma  in  order  to 
constitute  fresh  cells.  After  death,  their  transforma- 
tion into  microbes  produces  putrid  fermentation,  an- ' 


292          MICROBES,   FERMENTS,   AND  MOULDS. 

their  existence  is  prolonged  far  beyond  that  of  the 
organisms  of  which  they  temporarily  formed  part. 
Thus  the  microzyma  of  chalk,  which  doubtless  have 
their  source  in  the  animal  and  vegetable  tissues  of 
that  epoch,  are  still  living  after  a  repose  of  many 
thousand  centuries,  and  may  be  transformed  into 
bacteria  if  supplied  with  the  fitting  nutritive  liquid, 
as  Bechamp  has  demonstrated. 

This  is  undoubtedly  a  very  attractive  theory, 
which  would  explain  a  larger  number  of  facts  than 
the  theories  previously  stated,  yet  it  is  impossible  to 
make  it  agree  with  some  of  these  facts,  while  they 
are  readily  explained  by  the  parasitic  theory.  Such, 
for  example,  are  the  phenomenon  of  putrefaction,  and 
the  benefits  of  Lister's  dressing,  and  of  Guerin's  pro- 
tective method  applied  to  wounds. 

Robin,  in  his  theory  of  blastema,  also  stated  that 
putrefaction  took  place  without  the  intervention  of 
any  external  agent. 

It  is,  however,  now  known  that  when  dead  bodies 
are  protected  from  air-germs,  they  do  not  putrefy,  but 
become  mummies.  Such  is  the  case  with  the  bodies 
which  have  been  preserved  for  many  centuries  in  the 
crypt  of  one  of  the  churches  in  Bordeaux,  and  which, 
without  any  antiseptic  preparation,  have  gradually 
passed  into  the  state  of  mummies.  Many  underground 
buildings  and  caverns,  in  which  the  air  is  dry  and 
the  temperature  invariable,  present  conditions  favour- 
able to  such  transformation,  doubtless  because  this 


CONCLUSION.  293 

situation  is  unfavourable  to  the  life  of  the  lower 
plants. 

The  theory  of  microzyma  explains  the  transmission 
of  diseases  by  the  organized  elements  of  the  virus, 
while  the  filtered  liquid  of  the  same  virus  is  unin- 
jurious,  and  in  this  respect  it  is  more  in  accordance 
with  facts  than  the  theory  of  blastema;  but  it  does 
not  explain  the  effect  of  the  exclusion  or  sifting  of 
the  air  by  Gue'rin's  dressing,  nor  that  of  carbolic  acid 
in  Lister's  dressing.  In  fact,  if  the  virulent  microzyma 
are  in  the  patient's  body,  and  have  no  external  source, 
it  is  difficult  to  understand  of  what  use  this  process 
can  be.  It  is  evident  that  the  cotton  wool,  which  only 
arrests  the  solid  particles  of  the  air,  while  admitting 
the  air  itself,  must  act  by  warding  off  something 
suspended  in  the  air,  and  the  matter  in  suspension 
can  only  be  organized  bodies,  or  air-germs. 

Theory  of  Ptomaines. — Special  alkaloids  (septine) 
were  discovered  by  Panum  in  pus  and  by  Selmi  and 
Gautier  in  putrefying  matter  (ptomaines),  and  par- 
tizans  of  the  theory  of  non-organized  virus  appeal  to 
these  as  a  last  resource.  It  has  been  supposed  that 
these  ptomaines  or  toxic  alkaloids  were  the  product 
of  putrefaction,  or  morbid  changes  which  were  purely 
chemical,  produced  in  the  tissues  and  fluids  of  the 
system,  without  any  external  intervention  of  microbes. 
This  a  priori  idea  does  not  really  differ  from  Robin's 
theory  of  blastema.  If  it  is  accepted,  all  pathogenic 
microbes  resemble  Sattler's  jequirity  bacillus,  which 


294          MICROBES,  FERMENTS,   AND  MOULDS. 

certainly  lives  and  is  developed  in  the  toxic  juice  of 
the  seeds  of  Abrus  precatorius,  but  which,  as  Klein 
has  shown,  has  no  influence  on  the  artificial  conjunc- 
tivitis produced  by  the  aid  of  this  liquid. 

This  theory  of  ptomaines  without  microbes  is, 
however,  inconsistent  with  an  impartial  study  of  facts. 
It  is  true  that  a  suitable  filtration  will  separate  the 
ptomaine  from  its  microbe ;  but  the  converse,  as  in 
the  case  of  the  jequirity  liquid,  is  impossible.  When 
this  microbe  is  separated  from  the  original  liquid, 
and  transferred  to  the  infusions  of  successive  cultures, 
so  as  to  purify  it  from  every  foreign  element,  it 
continues  to  produce  its  characteristic  ptomaine,  which 
is  manufactured  completely  at  the  expense  of  the 
culture  liquid,  as  Pouchet's  recent  experiments  on  the 
ptomaine  of  cholera  have  shown.  There  is  no  ptomaine 
without  its  special  microbe,  any  more  than  there  is 
ergotine  without  Claviceps  purpurea,  or  vinegar 
without  Mycoderma  aceti. 

Pasteur's  Microbian  Theory  is  the  only  one  which 
explains  all  Facts. — The  microbian  theory  is  the  only 
one  which  is  not  obliged  to  have  recourse  to  the  vague 
expressions  with  which  medicine  was  formerly  content 
to  explain  the  contagion  of  diseases,  and  which  still 
satisfies  Jousset  de  Bellesme,  when  he  speaks  of  the 
wholly  obscure  conditions  which  accompany  the  pro- 
duction of  these  diseases.  All  the  expressions  of 
miasmata,  virus,  effluvia,  etc.,  which  were  in  use  twenty 
years  ago  to  designate  that  unknown  agency  which 


CONCLUSION.  295 

constitutes  contagion,  could  only  be  defined  by  having 
recourse  to  the  term  "  catalytic  action/'  which  merely 
placed  the  solution  of  the  problem  another  step  back, 
and  substituted  one  unknown  thing  for  another.*  The 
parasitic  theory  will  have  done  much  for  science  if  it 
only  delivers  us  from  "miasmata,"  "effluvia,"  and, 
above  all,  "  catalytic  action."  As  soon  as  it  had  been 
shown  that  miasmata  and  effluvia,  as  well  as  virus,  were 
only  air-germs — that  is,  microbes  and  their  spores — a 
brilliant  light  was  thrown  on  all  pathology,  of  which 
the  benefits  may  be  measured  by  the  great  work  accom- 
plished in  this  direction  within  the  last  ten  years. 

This  theory  has  given  us  Guerin's  protective  treat- 
ment of  wounds,  Lister's  antiseptic  dressing,  and 
Pasteur's  new  vaccine,  and  these  three  great  dis- 
coveries are  enough  to  render  the  hypothesis  immortal, 
even  admitting  that  it  is  only  an  hypothesis.  The 
adverse  theories,  when  opposed  to  the  microbian 
theory,  can  show  us  no  progress  effected  in  science, 
and  this  suffices  to  condemn  them. 

Moreover,  the  microbian  theory  is  no  longer  in 
the  primitive  stage  in  which  it  can  be  regarded  as 
a  pure  hypothesis,  since  it  has  entered  the  domain 
of  positive  facts.  Before  an  infectious  disease  can  be 
considered  due  to  the  presence  of  a  specific  microbe, 

*  See,  for  example,  the  article  Miasmes  in  Nysten's  Dictionary 
(LittriJ  and  Jtuliin,  edit.  1864):  "Miasma  is  constituted  by  the  organic 
substances  of  the  air,  in  different  stages  of  catalytic  modification."  These 
words  are  printed  in  italics  by  Robin  himself.  See  also  the  words 
J''j]l uvcs,  Cakdytiques,  Virus,  etc.,  in  the  same  dictionary. 


296          MICROBES,  FERMENTS,   AND  MOULDS. 

it  is  indispensable  to  submit  it  to  the  test  of  the  four 
following  rules,  which  have  been  clearly  established 
by  Koch : — 

1.  The  microbe  in  question  must  have  been  found 
either  in  the  blood  or  tissues  of  the  man  or  animal 
which  has  died  of  the  disease. 

2.  The    microbe    taken    from    this    medium   (the 
blood  or  tissues,  whichever  it  may  be),  and  artificially 
cultivated  out  of  the  animal's  body,  must  be  trans- 
ferred from  culture  to  culture  for  several  successive 
generations,    taking    the    precautions    necessary    to 
prevent  the  introduction  of  any  other  microbe  into 
these  cultures,  so  as  to  obtain  the  specific  microbe, 
pure  from  every  kind  of  matter  proceeding  from  the 
body  of  the  animal  whence  it  originally  came. 

3.  The  microbe,  thus  purified  by  successive  cultures, 
and  reintroduced  into  the  body  of  a  healthy  animal 
capable  of  taking  the  disease,  ought  to  reproduce  the 
disease  in  question  in  that  animal  with  its  charac- 
teristic symptoms  and  lesions. 

4.  Finally,  it  must  be  ascertained  that  the  microbe 
in  question  has  multiplied  in  the  system  of  the  animal 
thus  inoculated,  and  that  it  exists  in  greater  number 
than  in  the  inoculating  liquid. 

These  four  conditions  are  necessary  and  sufficient, 
and  in  the  present  state  of  science  they  may  be 
regarded  as  fulfilled  in  a  considerable  number  of 
diseases :  in  anthrax,  fowl  cholera,  swine  fever, 
glanders,  small-pox,  tuberculosis,  erysipelas,  and  even 


CONCLUSION.  297 

in  Asiatic  cholera.  These  are  undoubtedly  microbe 
diseases  in  every  sense  of  the  term. 

The  opposition  which  the  microbian  theory 
encounters  in  pathology  is  not  new,  and  need  not 
surprise  us.  In  all  ages  medicine  has  clung  to  its  old 
traditions,  and  has  been  unwilling  to  renounce  the 
habit  of  regarding  disease  as  something  mysterious, 
just  as  in  the  times  of  ancient  magic,  of  which  our 
modern  seers  and  sorcerers  are  a  relic.  The  parasitic 
theory  is  too  simple  and  natural  to  be  accepted  without 
a  struggle,  but  its  earlier  achievements  are  a  good 
omen  for  the  future.  We  need  scarcely  remind  our 
readers  that  at  the  beginning  of  this  century  the 
parasitic  theory  of  itch  encountered  the  same  opposi- 
tion, yet  no  physician  now  doubts  that  Sar  copies 
scabiei  is  the  sole  cause  of  the  disease.  Somewhat 
later,  towards  the  middle  of  the  century,  when  the 
presence  of  special  microphyta  was  ascertained  in 
most  skin-diseases,  the  importance  of  this  discovery 
was  denied;  yet  few  physicians  will  now  dispute 
that  these  microphyta  are  the  chief,  or  rather  the 
sole  cause  of  these  diseases. 

So,  again,  in  anthrax,  when  we  observe  the  blood 
and  all  the  organs  filled  with  bacteridia  (Bacillus 
antkracis),  it  can  hardly  be  denied  that  this  disease 
is  essentially  parasitic.  Since  these  bacteridia  are 
living  beings  which  grow,  are  reproduced,  and  breed 
with  great  energy,  it  must  be  admitted  that  their 

presence  constitutes  an  immediate  danger,  especially 
14 


298          MICROBES,   FERMENTS,  AND  MOULDS. 

since  it  is  known  that  they  elaborate,  at  the  expense 
of  the  organism,  a  violent  poison  (ptomaine),  which 
penetrates  wherever  the  bacteridia  cannot  find  their 
way.  It  can  hardly  be  said  that  in  this  case  the 
bacteridia  are  only  a  "  secondary  phenomenon ; "  that 
is,  an  unimportant  complication  which  gives  no  cause 
for  uneasiness. 

What  we  have  here  said  of  anthrax  also  applies 
to  other  diseases :  to  diphtheria,  small-pox,  and  inter- 
mittent fever.  We  venture  to  say^that  if  our  instru- 
ments were  not  sufficiently  powerful  to  enable  us  to 
see  the  organisms  which  cause  these  diseases,  reason 
alone  would  oblige  us  to  admit  their  existence,  from 
our  general  knowledge  of  the  cause  and  nature  of 
contagious  diseases.  The  word  "contagion"  implies 
microbe,  and  the  simplicity  of  the  theory  gives  it 
value,  and  permits  us  to  regard  it  as  the  expression 
of  actual  facts. 

After  this,  it  is  unimportant  to  know  whether  the 
microbe  is  itself  the  contagion,  or  only  its  vehicle ;  if 
it  acts  by  itself,  or  only  by  the  production  of  ptomaine ; 
if  there  is  a  specific  microbe  for  each  kind  of  disease, 
or  if  this  microbe  is  susceptible  of  transformation,  like 
other  living  things,  according  to  the  nature  of  the 
medium  in  which  it  is  nourished.  These  are  secondary 
questions,  of  which  the  future  will  doubtless  afford  the 
solution,  but  which  do  not  affect  the  principle  of  the 
parasitic  theory.  That  theory  is  only  just  established ; 
each  day  brings  a  fresh  stone  to  the  edifice,  but  we 


CONCLUSION.  299 

must  not  yet  expect  it  to  be  complete  in  all  its  parts. 
The  advance  of  science  may  modify  its  details,  but  it 
may  be  asserted  that  the  foundation  itself  will  remain, 
since  it  relies  on  the  simple  and  natural  interpretation 
of  facts, 


APPENDIX. 


TERMINOLOGY   OF   MICROBES  :   VARIATIONS   IN   DENOMINATION 
AND   CLASSIFICATION. 

IN  consequence  of  the  polymorphism  of  microbes,  the 
terminology  employed  by  different  authors  is  very  unstable. 
We  have  given  the  established  morphological  classification 
which  is  still  most  generally  used,  but  we  must  here  add 
some  remarks  which  will  make  it  more  easy  to  understand 
the  works  recently  published  on  microbes,  such  as  Les 
Bacteries,  by  Cornil  and  Babes,  and  Micro-organism*  and 
Diseases,  by  Klein. 

We  must  first  note  the  tendency  to  eliminate  the  names 
of  two  genera  :  Bacterium  and  Vibrio. 

Cornil  and  Babes  give  the  name  Bacteria,  which  is  the 
title  of  their  work,  to  the  whole  group  of  Bacteriacece,  or 
microbes  strictly  so  called,  regarded  as  a  distinct  order. 
They  have  consequently  been  led  to  suppress  the  penus 
Bacterium,  in  order  to  avoid  confusion ;  and  most  of  the 
species  formerly  assigned  to  the  genus  Bacterium  are 
regarded  by  them  as  Bacillus,  whether  the  individual  is 
long  or  short,  mobile  or  stationary.  In  the  description 
of  the  microbes  of  human  diseases,  we  have  conformed 


302  APPENDIX. 

to  this  nomenclature,  which  appears  to  be  adopted  by 
histologists,  so  as  not  to  overload  the  synonymy  of 
microbes,  which  is  already  somewhat  encumbered.  It  is 
probable,  moreover,  that  this  assimilation  is  correct, 
and  that  most  bacilli  pass  through  a  phase  in  which  they 
are  short  and  mobile,  before  becoming  elongated  and 
stationary.  On  the  other  hand,  certain  types  of  the  old 
genus  Bacterium — for  instance,  the  bacteria  in  the  form  of 
an  8 — should  rather  be  assigned  to  the  genus  Micrococcus, 
or  to  the  new  genus  Diplococcus. 

With  respect  to  the  genus  Vibrio,  it  seems  to  have 
been  originally  only  a  somewhat  heterogeneous  collection, 
comprising  both  the  chains  and  chaplets  of  micrococci  or  of 
short  bacteria,  and  the  strictly  unicellular  organisms  which 
might  be  assigned  to  the  genus  Spirillum.  Klein,  how- 
ever, reserves  this  genus  for  Vibrio  rugula  and  V.  Serpens. 

The  genus  Hicrococcus   (Hallier)    is   also   termed   by> 
Cohn,   Spherobacterium,    and   these   two   names   are   now 
given  to  the  only  unicellular  microbes  which  are  round 
or  oval,  stationary,  and  consequently  devoid  of  eilium  or 
flagellum,  the  organ  of  propulsion. 

These  micrococci  may  be  in  the  form  of  chains  or 
chaplets  (torula),  dumb-bells  (Klein),  the  figure  8  (Diplo- 
coccus, Billroth),  groups  of  four,  and  zoogloea3  or  in  masses 
of  greater  numbers. 

The  genus  Bacterium  (Microbacterium,  Cohn)  differs 
from  the  foregoing,  as  Klein  states,  chiefly  in  the  oval  or 
cylindrical  form  of  its  cells,  and  still  more  by  the  presence 
of  a  eilium  or  flagellum  at  one  extremity,  which  gives  a 
spontaneous  movement.  They  may  thus  assume  the  form 
ot  a  sponge-cake  and  of  a  dumb-bell  when  they  divide  in 
two,  and  may  also  form  short  chains  or  zoogloeae.  As  we 
have  already  said,  most  of  these  organisms  are  assigned 


APPENDIX.  303 

by  Cornil  to  the  genus  Bacillus ;  at  any  rate,  in  the  case 
of  organisms  peculiar  to  human  diseases. 

The  genus  Bacillus,  according  to  Klein  (Deswo&ac- 
terium,  Cohn),  includes  microbes  in  the  form  of  more  or 
less  elongated  rods,  which  divide  by  fission  into  straight, 
curved,  or  zigzagged  chains,  formed  of  elements  generally 
in  contact  by  their  sqnare-cut  edges,  and  which,  may  be 
considerably  elongated  in  the  form  of  Leptothrix. 

Some  of  these,  when  isolated  or  in  short  chains,  pos- 
sess a  flagellum  at  one  extremity,  and  are  consequently 
mobile — such  is  the  case  with  Bacillus  subtilis  and  most 
of  the  bacilli  of  putrefaction — but  they  lose  this  organ 
of  movement  on  passing  into  the  state  of  Leptothrix- 
Bacillus  anthracis  is  always  stationary,  and  devoid  of 
flagellum.  The  fact  that  there  is  in  this  genus  a  vibratory 
cilium,  and  consequently  motion,  breaks  down  the  barrier 
between  the  genera  Bacterium  and  Bacillus,  and  con- 
sequently justifies  Cornil's  view. 

The  genera  Spirillum  (Spirobacterium,  Cohn,)  and 
Spirochoete  are  much  more  rare,  and  have  not  given  rise 
to  the  same  variations  in  nomenclature. 

We  conclude  by  reproducing  the  classification  of 
Rabenhorst  and  Fliigge,  as  it  is  given  by  Cornil  and 
Babes,  in  order  to  serve  as  a  convenient  scheme  for  the 
pathogenic  bacteria  in  which  we  are  specially  interested  : 


304 


APPENDIX. 


CLASSIFICATION  OF  RABENHORST  AND  FLUGGE. 


.LDUiatcu,  u*  vuB£v*m  vi  iii  fcvugiveet/             ...            ...            ...      jute/  vct/vcw*. 

In  large  numbers 

Round 

and 

or 

/Solid  colonies      inegukr  colonies     

Ascococcus. 

cells.     Forming!    ^fu^pii.,         In  small  definite 
zoogloeajj                                    numbers 

in  th 

e  ^ 

and 

k  form  of  j 

regular  groups        ...        «. 

Sarcina. 

\A  single  circular  layer  

Clathrocystis. 

/'  Short,  isolated,  in  a  mass  or  in  zoogloeae         

Bacterium. 

Short,  jointed 

Bacillus. 

"3 

/Isolated, 
inter- 

•d  /  Straight 
S,  1  filaments. 

1 

,     jointed.     (  Thick 

Leptothrix. 
Beggiatoa. 

J 

Forming 
long 

laced, 
or  in 
bundles. 

|        Spiral     (  S^rt,  rigid  
^filaments-  (Long,  flexible        ... 

Spirillum  (Vibrio). 
Spirochoste. 

\ 

(  Streptothrix. 

With  false  ram 

ificationa 

(  Cladothrix. 

In  zoogloeae  ... 

Myconostoc. 

B. 

APPENDIX  TO  CHAPTER  III.  (p.  131). 

M1CROCOCCUS   OF   PHOSPHOKESCENCE. 

The  phosphorescence  of  the  sea  is  due  to  the  presence 
of  NoctiluccB,  protozoaria  of  the  group  of  Flagellata,  which 
come  to  the  surface  in  stormy  weather.  Many  other 
marine  animals  present  the  same  phenomenon.  The 
phosphorescence  of  rotten  fish  is  due  to  the  presence  of 
a  special  micrococcus  which  forms  large  circular  zoogloeae. 
The  same  micrococcus  also  appears  on  putrefied  meat 
and  imparts  to  it  a  phosphorescent  light. 


APPENDIX.  305 

a 

APPENDIX  TO  CHAPTER  III.  (p.  131). 

PLANT-DISEASES  CAUSED  BY  BACTERIA. 

The  presence  of  parasitic  bacteria  has  been  recently 
pointed  out  as  the  cause  of  diseases  in  plants.  In  1880, 
Burril,  of  Illinois,  U.S.,  has  declared  the  shrivelling  of 
pears  to  be  due  to  a  bacterium  which  attacks  fruit-trees, 
and  of  which  he  succeeded  in  making  an  artificial  culture. 
In  1882,  the  jaundice  of  hyacinth  bulbs  was  ascribed  by 
Wakker,  of  Amsterdam,  to  the  development  of  a  bacterium 
between  the  layers,  which  may  finally  destroy  the  plant. 
In  August,  1885,  Luiz  de  Andrade  Corvo  presented  a 
paper  to  the  Academy  of  Sciences,  in  which  he  asserted 
that  the  vine- disease  ascribed  to  Phylloxera  vastatrix  is 
really  due  to  a  bacillus,  or  rather,  according  to  his  de- 
scription, to  a  bacterium,  which  is  always  found  in  the 
tubercles  of  the  radicles  and  in  the  tissues  of  the  vine 
which  are  affected  by  this  disease,  termed  by  him  tuber- 
culosis. They  are  also  found  in  the  body  of  the  insect, 
Which  thus  becomes  simply  the  agent  of  contagion. 

Neither  Wakker  in  1882,  nor  Burril  in  1880,  was  the 
first  to  point  out  the  presence  of  microbes  in  the  diseased 
tissues  of  plants.  As  early  as  the  year  1869,  Bechamp 
noticed  the  presence  of  microzyma,  that  is,  bacteria,  in  the 
affected  parts  of  plants  (Comptes  rendus  de  VAcademie  des 
Sciences,  vol.  Ixviii.  p.  4GG). 


306  APPENDIX. 

D. 

APPENDIX  TO  CHAPTER  IY.  (p.  143). 

PTOMAINE  OF  THE  MICROBE  OF  FOWL  CHOLERA. 

Duclaux  cites  the  following  fact  in  his  book,  Ferments 
et  Maladies: — "If  a  fowl  is  inoculated  with  a  few  drops 
from  a  culture  of  fowl  cholera,  the  bird  sickens  and  dies ; 
but  if  the  liquid  has  been  filtered  before  using  it,  through 
plaster  or  porous  china,  the  disease  produced  is  not  fowl 
cholera.  The  bird  rolls  himself  up  and  falls  into  a  passing 
sleep,  from  which  he  is  roused  by  the  slightest  noise. 

"  After  a  few  hours,  his  recovery  is  complete.  Thus 
there  are  two  kinds  of  symptoms  in  fowl  cholera,  of  which 
the  most  apparent  is  due  to  a  species  of  narcotic  (ptomaine) 
secreted  by  the  microbe,  but  capable  of  independent  action, 
and  not  in  general  ending  fatally." 


E. 


APPENDIX  TO  CHAPTER  V.  (p.  171). 

CESSPOOLS.      SYSTEM   OF   CARRYING    EVERYTHING   TO   THE    - 
SEWERS. 

This  system,  so  long  advocated  in  Paris  by  Durand- 
Claye,  implies  that  the  water  should  pour  into  the  recep- 
tacles, so  as  constantly  to  flush  the  drain-pipes.  A  minimum 
of  ten  litres  per  diem  to  each  inhabitant  is  necessary  for 
this  purpose. 

The   household   water  and  rain-water  likewise   pass 


APPENDIX.  307 

into  evacuation  pipes  of  the  sewer  by  sypecial  sphons,  and 
help  to  flush  them.  This  system  has  been  applied  to  the 
Hotel  de  Yille,  to  the  new  Guards'  barracks,  to  a  certain 
number  of  primary  schools,  and  to  many  private  houses. 
The  municipal  administration  proposes  to  apply  this 
system  to  most  of  the  schools,  hospitals,  and  barracks,  of 
which  the  sanitary  condition  is  at  present  far  from  satis- 
factory. They  hope  eventually  to  extend  the  same  system 
to  all  private  houses,  so  as  to  do  away  with  the  cesspools — 
a  reform  already  effected  in  many  foreign  cities,  and 
notably  in  Germany. 


F. 

APPENDIX  TO  CHAPTER  V.  (p.  172). 

THE    SEWERS   OF    PARIS    AND   THE    PLAIN   OF   OENNEVILLIERS. 

The  water  issuing  from  the  main  sewer  of  the  city  is 
partly  turned  into  the  Seine,  partly  into  the  plain  of 
Gennevilliers,  and  used,  by  a  system  of  irrigation,  for  fer- 
tilizing the  soil.  There  was  some  fear  lest  the  vegetable 
mould  might  be  saturated  with  fertilizing  matter,  but  the 
presence  of  a  special  microbe  was  ascertained,  which  re- 
duces organic  matter  to  its  inorganic  constituents,  and 
thus  adapts  them  to  be  absorbed  by  plants.  Schloesing 
and  Muntz,  who  have  studied  this  microbe,  term  it  the 
nitrifying  microbe.  The  same  system  of  sewer-irriga- 
tion will  shortly  be  applied  to  another  place  in  the  neigh- 
bourhood of  Paris,  Aeheres,  near  the  forest  of  Saint- 
Germain. 


308  APPENDIX. 

G. 

APPENDIX  TO  CHAPTER  V.  (p.  172). 

USEFUL   MICROBES. 

We  have  said  that  numerous  bacteria  exist  in  the  diges- 
tive canal  of  a  man  in  good  health.  Recent  researches  by 
Duclaux,  Richet,  and  Bourquelot  tend  to  show  that  these 
microbes  are  not  only  innoxious,  but  that  they  play  an 
active  part  in  gastric  digestion,  and  especially  in  the 
transmutation  of  albumins  into  peptones.  Since  they  are, 
in  fact,  living  ferments,  the  transmutation  is  retarded,  if 
these  microbes  are  eliminated.  It  is  therefore  probable 
that  they  manufacture  pepsin. 

Pasteur's  experiments  also  tend  to  show  that  microbes 
aid  the  germination  of  plants.  If  the  microbes  contained 
in  vegetable  mould  are  withdrawn  from  it,  without  taking 
away  any  other  constituent,  germination  is  retarded,  arid 
effected  with  difficulty. 


H. 

APPENDIX  TO  CHAPTER  Y.  (p.  241.) 

PTOMAINES   OF   FISH. 

Salt  and  smoked  fish  often  produce  in  those  who  eat 
them  violent  poisoning,  which  may  even  end  in  death. 
Aurep,  of  Kharkov,  has  recently  studied  these  causes, 
and  ascribes  them  to  a  ptomaine  secreted  by  a  microbe, 
or  perhaps  evolved  from  the  fish  itself  during  life,  under 
the  morbid  influence  of  this  microbe. 


INDEX. 


Abrine,  282 

Abrus  precatorius,  281 

Acarus,  51 

Acescence  in  wine,  99 

Achorion  Tteratophagus,  63 

Schcenlenii,  52,  277 

Acidity  of  wines,  99 

Acinetce,  3 

Actinospora  chartarum,  46 

Action  by  presence,  71 

Aerobies,  117,  118 

Aeroscope,  160 

Agaricus  comestibilis,  10,  12 

melleus,  41 

Agnail,  236 

Alkaloids,  238-241 

Alopecia,  60 

— —  areata,  131 

Amertume,  98 

Ammoniacal  fermentation,  107 

Aracebae,  3 

Anaerobies,  117,  118 

AnguiUidce,  97 

Antheridinm,  30 

Anthracnosis,  38 

Anthrax,  132-142 

Antiseptic  dressing,  242-245 

Antiseptics,  253-257 

Appert's  process,  251 

Apyrexia,  185 


Ascarides,  248 
Ascococcus,  91,  93,  304 
Ascomycetes,  13,  20 
Ascophora  mucedo,  46 
Aspergillus,  33,  275,  278 

glaucus,  26 

Attennation   of  pathogenic   mi. 

crobes,  269 
Aubernage,  39 


B 


Bacillus,  92,  304 

amylobacter,  110 

butyricus,  110 

komma,  198,  203 

of  anthrax,  133,  134 

of  cholera,  197,  198 

of  foot  sweat,  232 

of  gangrene,  232 

of  glanders,  149 

of  leprosy,  228 

of  malaria,  183 

of  phthisis,  225 

of  pneumonia,  230 

subtilis,  175 

Bacteridia,  93 

,  their  vegetable  nature, 

Bacterium,  93,  301-304 

centginosum,  130 

bombycis,  152 

cyanogenum,  129 


310 


INDEX. 


Bacterium  decalvans,  131 

lineola,  95 

porri,  232 

prodigiosum,  127 

subtilis,  175 

termn,  86,  87,  88 

xanthinum,  129 

Baregine,  120 
Basides,  12 
Basidiomycetes,  14 
Bechamp's  theory,  291 
Beggiatoa,  119,  304 

alba,  119 

Bitterness  of  wine,  103 
Blastema,  theory  of,  286 
Boil,  236 
Boissons,  82 
Botrytis  bassiana,  50 
Bougie  Chamberland,  249 
Butyric  fermentation,  105,  109 


Carbuncle,  236 
Caries,  dental,  177-179 
--  ,  dry,  63 
-  ,  of  cereals,  17 
Carpozyma  apiculata,  75 
Catallacta,  3 


Cattle  plague,  146 
Cellulose,  9,  10 
Chcetonium  chartarum,  46 
Chalk,  microbes  of,  124 
Chamberland  filter,  240-248 
Chlorococcus,  160 
Chlorophyl,  10 
Cholera,  fowl,  142 

-  ,  mode  of  propagation,  207 
--  ,  microbe  of,  195-206 
Cilia,  vibrating,  88 
Cladothrix,  92 

-  dichotoma,  93 
Classification  of  microbes,  91,  301 
--  of  fungi,  13 
Clathrocystis,  304 

Claviceps  purpurea,  20,  21 
Coprins,  44 


Cordiceps,  47,  49 

Corpuscles,  vibratile,  151 

Cossus,  47 

Cow-pox,  211,  214 

Croup,  microbe  of,  215-222 

Culture  flasks,  162,  264 

Culture  of  microbes,  163,  258- 

268 
Cyanophycese,  119 


Dematium  gigantewn,  45 

Desmobacterium,  303 

Diastase,  80 

Diatomacece,  3 

Diblastic  theory,  168 

Diphtheria,  microbe  of,  220 

Diplococcus,  302 

Disease,  white,  33 

Diseases,  action  of  microbes  in, 

237-241,  294 
of  domestic  animals,  132- 

155 

,  human,  156-241 

of  plants,  305 

of  potato,  31 

of  silkworms,  50,  150-155 

of  the  vine,  32-42 

of  wines,  98  -105 

•,  produced  by  microbes,  7 

Drawings  of  microbes,  263 


Earth-worms,  32,  137 

Ehrlich   (staining  method),  225, 

263 

Elephantiasis,  228 
Entomophthora  2'lanchoni,  49 

rimosa,  49 

Entomophthorese,  49 
Ergot  of  maize,  24 

of  rye,  20,  21 

Ergotine,  23 
Ergotism,  23 
Erisyphe,  27 


INDEX. 


Sll 


Erisyphe  TucJceri,  27,  33 
Erysipelas,  microbe  of,  232,  233 
Eurotium  repens,  25 
Exanthemata,  209-215 


Farcy,  149 
Favus,  54 
Fermentation,  66-84. 

,  acetic,  95 

,  alcoholic,  75 

,  annnoniacal,  107 

,  butyric.  110 

f  lactic,  106 

,  of  beer,  78 

,  putrefactive,  112 

,  vinous,  74 

,  viscous,  104 

Ferment,  of  beer,  79-81 

of  bread,  84 

of  fruit,  76 

of  wine,  74,  75,  76 

Ferments,  66-72 

Fevers,  eruptive,  209-215 

,  intermittent,  179-187 

,  jungle,  187 

,  of  horses,  194 

,  recurrent,  187 

,  typhoid,  191-194 

1  typhus,  191 

,  yellow,  189,  190 

Filter,  Chamberland,  240-248 
Flacherie,  154,  155 
Flfigellata,  3 
Flfigellum,  88 
Fleurs  de  vin,  98 
Fowl  cholera,  1 12 
Fuchsin,  26  L 
Fungi,  3,  9-65 


Gangrene,  232 
Germs  of  the  air,  156-165 
Glairine,  120 
Glanders,  149 


Glucose,  67 
Goitre,  232 
Gonorrhoea,  230 
Graisse,  98 
OregarinidoB,  3 
Guerin's  dressing,  212 


Hay,  infusion  of,  162 
Hepialus,  47 
Herpes,  circinnate,  56 
Himantia  cellaria,  43 
Hymenium,  12 
Hymenomycetes,  15 
Hyphse,  10 


Immunity,  271 
Infusoria,  3 
Inoculation,  269 

for  anthrax,  139 

for  cholera,  201 

for  pneumonia,  145 

for  rabies,  148 

Instruments   for   research,   258, 

259 

Isariapulveracea,  49 
sphingum,  48 


.Tequirity,  microbe  of,  281 


Kava,  83 
Kirschwasser,  83 
Koumiss,  83 


Laboratory  research,  258-271 
Labyrinthulce,  3 


312 


INDEX. 


Lamellae,  12 

Leprosy,  microbe  of,  228 

Leptothrix,  92,  304 

buccalis,  175 

,  polymorphism  of,  274 

Lichens,  273 

Liquids,  culture,  162,  268 

Lister's  dressing,  244 


Malaria,  179 

bacillus,  183 

Malt,  80 

Marsh  fever,  179-187 

Measurement  of  microbes,  263 

Merulius  destruens,  45 

Methods  of  culture,  263 

Methyl-violet,  261 

Miasma,  170 

,  human,  191 

Microbes,  aerobic  and  anaerobic, 
117 

,  chromogenic,  126-131 

,  classification  of,  91,  304 

,  culture  of,  263-269 

,  defence  against,  242—257 

destroyers  of  building  ma- 
terials, 123,  124 

,  in  general,  1-8 

of  bad  bread,  130 

of  baldness,  131 

of  blue  milk,  129 

— —  of  domestic  animals,  132— 
155 

of  human  diseases,  156-241 

of  jequirity,  281 

of  saltpetre,  121 

of  sulphurous  waters,  119, 

120 

of  the  air,  156-161 

of  the  mouth,  172-179 

of  the  saliva,  173 

of  the  soil,  166 

of  urine,  107 

of  water,  165,  166 

,  part  played  by,  6,  7 

,  pathogenic,  282-284 

polymorphism  of,  272-284 


Microbes,  ptomaines  of,  237-241, 

306 

,  septic,  282 

,  strictly  so  called,  85-90 

,  their  mode  of  action,  237- 

241 

,  useful,  6,  305 

,  vegetable  nature  of,  85-90 

Microbian  theory,  Pasteur's.  294- 

299 
Micrococcus,  91,  92,  304. 

auriantiacus,  129 

bombycis,  154 

candidus,  129 

chlorinus,  129 

cyamtg,  129 

diphthericus,  215 

fulvus,  129 

of  gonorrhoea,  231 

of  peritonitis,  234 

of  pneumonia,  229 

of  scarlatina,  210 

of  small-pox,  211,  212 

prodigiosus,  127 

septicu*,  234 

urece,  107,  108 

violaceus,  129 

Microsporece,  58 
Microsporidia,  152 
Microsporon  Audouini,  58 

diphtericum,  220 

furfur,  56,  57,  278 

Microtome,  259 

Microzoaria,  4 

Microzyma,  4,  291,  305 

Mildew,  35,  36 

Mixture    of  different  microbes, 

279 

Molinia,  46 
Monera,  3 
Montsouris,  159 
Morts  flats,  154 
Motion  of  microbes,  88 
Moulds,  of  dog's  excrement,  27 

of  leather  and  fruit,  25,  26 

of  paper,  46 

Mucor  caninus,  27 

herbarium,  46 

mucedo,  28,  46 


INDEX. 


313 


rp,  27 
Muscardine,  50 
Washroom,  edible,  9,  11 
Mycoderma  aceti,  95 

vini,  76,  96 

Myconostoc,  304 
Alyxomycetes,  3 

N 

Noctilucce,  304 
Nosema  bombycis,  152 
Nostoc,  90 

O 

CEcidiospores,  16 
(Ecidium  berberidis,  17 

rhamni,  17 

O'idiain,  33 

albicans,  61,  278 

lactis,  278 

Onychomycosis,  63 
Oogonium,  30 
O&mycetes,  13,  27 
Oospores,  27 

Ophidomonas  sanrfninra,  128 
Ophthalmia,  purulent,  231 
Orleans  process,  96 
Oscillaria,  9,  119,  185 
Oscillatoria,  119 
Osteomyletis,  236 


Palmella  febrilis,  182 

miriftca,  127 

Panistophyton  ovale,  152 
Pebrine,  150-154 
Pelade,  spurioup,  24 

,  true,  58,  59 

Pellagra,  18,  24 
Pelletage,  19 
Penicillium,  27,  275,  278 

ferment,  275 

racemo««m,  47 

Peronospora  Barcinonce,  202 

calotheca,  29,  30 

infestans,  31,  37 

,  35-37 


Peyer's  glands,  192,  ii?i. 
Phlegmon,  237 
Phoma  uvicolu,  38 
Phosphoresceace,  304 
Photogruph'j  of  micrubep,  /(»3 
Phthisis,  223-228 
Phycvr.rnmycecs,  90 
Phylloxera  vastatrix.  33 
Piper  meihysticum,  83 
Pipette,  260 
J'ifyrio£t#  capitis,  59,  60 

verstcoior,  56 

Pneumonia,  229 

Polymorphism  of  microbes,  27fc- 

284 

Polypus,  232 
Pousse,  100 
Powdered  meats,  252 
Preparations,  2G1 
Protista,  3-8 
Protococcus,  160 

nivalis,  128 

PtomaYnes,  239,  293 
Puccinia  coronata,  17,  18 

favi,  54 

graminis,  15-17 

Puerperal  peritonitis,  234 
Pus-corpuscles,  234,  235 
Putrefaction,  112-117 
Pyaemia,  235 
Pyrochoria  apterus,  49 


Rabies,  147-149 
Eeagents,  non-staining,  261 

,  staining,  261 

Ringworm,  52-54 
Robin's  theory,  286 
Ecesleria  hypogea,  40 
Rot,  40 
Rust,  cereal,  14 


Saccharnmyces  albicans,  61 
apiculatus,  76 


314 


INDEX. 


Saccharomyces  conglomeratus,  75 

ellipsoideus,  74 

• exiguus,  75 

minor,  84 

mycoderma,  61,  62,  76,  278 

Pastorianus,  75 

Eeesii,  76 

Saprolegnia  fer.ax,  47,  48 
Sarcina  ventriculi,  94,  95 
Scarlatina,  210 
Schizomycetes,  8,  86,  91,  158 
Schizophyta,  8,  86,  91,  158 
Sclerotis,  20 

Septic  and  pathogenic  microbes, 
282 

vibrio,  146 

Septicaemia,  234 

,  experimental,  146 

Septine,  238 
Sleepiness  of  fruit,  31 
Small-pox,  211,  212 
Smut  of  wheat,  19 
Solid  nutritive  substances,  267 
Sphacelium,  20,  21 
Sphaceloma  ampelium,  38 
Spherobacterium,  302 
Spirillum,  92,  304 

tenue,  114 

undulatum,  174 

Spirobacterium,  303 
Spirochcete,  92,  304 

buccalis,  173 

Obermeieri,  188 

plicatilis,  173 

Splenic  fever,  132-139 
Sporangium,  29 
Sporendonema  muscce,  47 
Spores,  air  charged  with,  104 

• ,  injected  into  the  blood,  27S 

Sporisorium  maidis,  18 
Staining  methods,  261 
Staphylococcus  pyogenus,  236 
Streptothrix,  204 
Forsteri,  232 


Sulphurous  waters,  119 
Sulphur,  application  of,  34 
Sweat,  red,  231 
Sweating  foot,  232 
Swine  fever,  143 
Sycosis,  55 
Symbiosis,  273 


Vaccination,  211-215,  269 

—  for  anthrax,  139 
Verdet,  18 
Vibrio,  3,  93,  101,  117,  301,  304 

rugula,  93,  118,  173,  174 

septicus,  146,  147 

serpens,  93,  302 

Vinegar,  ferment  of,  86,  95 
Viscous  fermentation,  105 


W 

Whitlow,  236 

Wine,  diseases  of,  98-105 

,  ferments  of,  74-78 


Xerosis,  232 


Yeast  of  beer,  78-82 


Znogalactina  imetropha,  127 
Zoogloeae,    114,    115,   129,   175, 

304 
Zjmase,  291 


D.  APPLETON  &  GO.'S  PUBLICATIONS, 

ANTS,  BEES,  AND  WASPS.  A  Record  of  Observations  on  tho 
Habits  of  the  Social  Hymenoptera.  By  Sir  JOHX  LUBBOCK,  Bart., 
M.  P.,  F.  R.  S.,  etc.,  author  of  "  Origin  of  Civilization,  and  the  ri-inii- 
tivc  Condition  of  Man,"  etc.,  etc.  With  Colored  Plates.  12mo. 
Cloth,  $2.00. 

14  This  volume  contains  the  record  of  various  experiments  made  with  ants,  bees,  and 
wasps  during  tin-  last  ten  years,  with  a  view  tj  test  their  mental  condition  and  powers 
of  sense.  The  principal  point  in  which  Sir  John's  mode  of  experiment  differs  'roni 
those  of  Huber,  Forel,  McCook,  and  others,  is  that  he  has  carefully  watched  and 
marked  parti.-ul.ir  insects,  and  has  had  their  nesta  under  observation  for  long  periods 
— one  of  his  ants'  nest.-,  having  Iwen  under  constant  inspection  ever  since  1S74.  His 
observations  are  made  principally  upon  ants,  hwau-e  they  show  more  power  and  flexi- 
bility of  mind ;  and  the  value  ui'  his  studies  is  that  they  belong  to  the  department  of 
original  research." 

"  We  have  no  hesitation  in  saying  that  the  author  has  presented  ns  with  the  most 
valuable  series  of  observations  on  a  special  subject  that  has  ever  been  produced,  charm- 
ingly written,  full  of  logical  deductions,  and,  when  we  consider  his  multitudinous  en- 
guffeUMBtf,  a  remarkable  illustration  of  economy  of  time.  As  a  contribution  to  insect 
psychology,  it  will  be  long  before  this  book  finds  a  parallel."— London  Athenaeum. 

DISEASES  OF  MEMORY.  An  Essay  in  the  Positive  Psychology. 
By  T».  RiBor,  author  of  "Heredity,"  etc.  Translated  from  the 
French  by  William  Iluutington  Smith.  12 mo.  Cloth,  $1.50. 

"  M.  Kibot  reduces  diseases  of  memory  to  law,  and  his  treatise  is  of  extraordinary 
interest."— Philadelphia  I*ress. 

"  Not  merely  to  scientific,  bat  to  all  thinking  men,  this  volume  will  prove  intensely 
int.  res  in-"— \eiu  York  Observer. 

"  M.  Kibot  has  bestowed  the  most  painstaking  attention  upon  his  theme,  and  nu- 
mrrous  examples  of  the  conditions  considered  greatly  increase  the  value  and  interest 
of  the  volume. "—Philadelphia  North  American. 

"To  the  general  reader  the  work  is  made  entertaining  by  many  illustrations  con- 
nected with  such  names  ns  Linnaeus,  Newton.  Sir  Walter  Scott,  Horace  Veruet,  Gus- 
tave  L)ore,  and  many  others."— ha  rrigburg  Telegraph. 

"The  whole  subject  is  presented  with  a  Frenchman's  vivacity  of  style."— Provi- 
dence Journal. 

u  It  is  not  too  much  to  say  that  in  no  single  work  have  so  many  curious  cases  been 
brought  together  and  interpreted  in  a  scientific  manner." — Boston  Evening  Traveller. 

MYTH  AND  SCIENCE.     By  TITO  VIGNOLI.     12mo.     Cloth,  f  1.50. 

"Ills  book  is  ingenious;  ...  his  theory  of  how  science  gradually  differentiated 
from  and  conquered  myth  is  extremely  well  wrought  out,  and  is  probably  in  essentials 
correct."— Saturday  Ketiew. 

"The  book  is  a  strong  one,  and  fir  more  interesting  to  the  general  reader  than  its 
title  would  indicate.  The  learning,  the  acut»ness,  the  strong  reasoning  power,  and  the 
scientific  spirit  of  the  author,  command  admiration."— New  York  Christian  Advocate. 

•'  An  attempt  made,  with  much  ability  and  no  small  measure  of  success,  to  trace  the 
origin  and  development  of  the  myth.  The  author  has  pursued  his  inquiry  with  much 
jritii  nee  and  ingenuity,  and  has  produced  a  very  readable  and  luminous  treatise." — 
PhUadtlpMa  North  American. 

"  It  is  a  curious  if  not  startling  contribution  both  to  psychology  and  to  the  early 
history  of  man's  development." — New  York  World. 


New  York :   D.  APPLETON  &  CO.,  1,  3,  &  5  Bond  Street, 


D,  APPLETON  &  CO.'S  PUBLICATIONS, 

THE  BRAIN  AND  ITS  FUNCTIONS.  By  J.  LUYS,  Physician 
to  the  Hospice  de  la  Salpetriere.  With  Illustrations.  12mo. 
Cloth,  $1.50. 

"No  living  physiologist  is  better  entitled  to  speak  with  authority  upon  the 
structure  and  functions  of  the  brain  than  Dr.  Luys.  His  studies  on  the  anatomy 
of  the  nervous  syetem  are  acknowledged  to  be  the  fullest  and  most  systematic 
ever  undertaken.  Dr.  Luys  supports  his  conclusions  not  only  by  his  own  ana- 
tomical researches,  but  also  by  many  functional  observations  of  various  other 
physiologists,  including  of  course  .Proiessor  Ferrier's  now  classical  experi- 
ments."—^. James's  Gazette. 

"  Dr.  Luys,  at  the  head  of  the  great  French  Insane  Asylum,  is  one  of  the  most 
eminent  and  successful  investigators  of  cerebral  science  now  living  ;  and  he  has 
given  unquestionably  the  clearest  and  mo?t  interesting  brief  account  yet  made 
of  the  structure  aud  operations  of  the  brain.  We  have  been  fascinated  by  this 
volume  more  than  by  any  other  treatise  we  have  yet  seen  on  the  machinery  of 
sensibility  and  thought;  and  we  have  been  instructed  not  only  by  much  that  is 
new,  but  by  many  sagacious  practical  hints  such  as  it  is  well  for  everybody  to 
understand." — The  Popular  Science  Monthly. 

THE  CONCEPTS  AND  THEORIES  OF  MODERN 
PHYSICS.  By  J.  B.  STALLO.  12mo.  Cloth,  $1.75. 

"Judge  Stallo's  work  is  an  inquiry  into  the  validity  of  those  mechanical  con- 
ceptions of  the  universe  which  are  now  held  as  fundamental  in  physical  science. 
He  takes  up  the  leading  modern  doctrines  which  are  based  upon  this  mechanical 
conception,  such  as  the  atomic  constitution  of  matter,  the  kinetic  theory  of  s:ases, 
the  conservation  of  energy,  the  neonlar  hypothesis,  and  other  views,  to  find  how 
much  stand*  upon  solid  empirical  ground,  and  how  much  rests  upon  metaphys- 
ical speculation.  Since  the  appearance  of  Dr.  Draper's  '  Religion  and  Science,' 
no  book  has  been  published  in  the  country  calculated  to  make  BO  deep  an  im- 
pression on  thoughtful  and  educated  readers  as  this  volume.  .  .  .  The  range 
and  minuteness  of  the  author's  learning,  the  acuteness  of  his  reasoning,  and  the 
singular  precision  and  clearness  of  his  style,  are  qualities  which  very  seldom 
have  been  jointly  exhibited  in  a  scientific  treatise."—  New  York  Sun. 

THE  FORMATION  OF  VEGETABLE  MOULD,  through 
the  Action  of  Worms,  with  Observations  on  their 
Habits.  By  CHARLES  DARWIN,  LL.  D.,  F.R.  S.,  author  of  "On 
the  Origin  of  Species,"  etc.,  etc.  With  Illustrations.  12mo. 
Cloth,  $1.50. 

"Mr.  Darwin's  little  volume  on  the  habits  and  instincts  of  earth-worm  p  is  no 
less  marked  than  the  earlier  or  more  elaborate  efforts  of  his  genius  by  freshness 
of  observation,  unfailing  power  of  interpreting  aud  correlating  facts, "and  logical 
viijor  in  generalizing  upon  them.  The  main  purpose  of  the  work  is  to  point  out 
the  share  which  worms  have  taken  in  the  formation  of  the  layer  of  vegetable 
mould  which  covers  the  whole  surface  of  the  land  in  every  moderately  humid 
country.  All  lovers  of  nature  will  unite  in  thanking  Mr.  Darwin  for  the  new  and 
interesting  light  he  has  thrown  upon  a  subject  so  long  overlooked,  yet  so  full  of 
interest  and  instruction,  as  the  structure  and  the  labors  of  the  earth-worm." — 
Saturday  Review. 

"  Respecting  worms  as  among  the  most  useful  portions  of  animate  nature, 
Dr.  Darwin  relates,  in  this  remarkable  book,  their  structure  and  habits,  the 
part  they  have  played  in  the  burial  of  ancient  buildings  and  the  denudation  of 
the  land,  in  the  disintegration  of  rocks,  the  preparation  of  soil  for  the  growtb 
tf  plants,  and  in  the  natural  history  of  the  world." — Boston  Advertiser. 

New  York :  D.  APPLETON  &  CO.,  1,  3,  &  §  Bond  Street. 


0.  APPLETON  &  00,'S  PUBLICATIONS, 


GENERAL  PHYSIOLOGY  OF  MUSCLES  AND  NERVES. 

By  Dr.  I.  ROSEXTHAL,  Professor  of  Physiology  at  the  University  of 
Erlangen.  With  seventy-five  Woodcuts.  ("International  Scientific 
Series.")  12mo.  Cloth,  $1.50. 

"  The  attempt  at  a  connected  account  of  the  general  physiology  of  muscles  and 
nerves  is,  as  far  as  I  know,  the  first  of  its  kind.  The  general  data  for  this  branch 
of  science  have  been  gained  only  within  the  past  thirty  years." — Extract  from 
Preface. 

SIGHT  :  An  Exposition  of  the  Principles  of  Monocular  and  Binocular 
Vision.  By  JOSEPH  LE  CONTE,  LL.  D.,  author  of  "Elements  of  Ge- 
ology"; "Religion  and  Science";  and  Professor  of  Geology  and 
Natural  History  in  the  University  of  California.  With  numerous 
Illustrations.  12mo.  Cloth,  $1.60. 
"  It  is  pleasant  to  find  an  American  book  which  can  rank  with  the  very  best 

of  foreign  works  on  thin  subject.    Professor  Le  Conte  has  long  been  known  as 

an  original  investigator  in  this  department ;  all  that  he  gives  un  is  treated  with 

a  master-hand.1'—  The  Nation. 

ANIMAL  LIFE,  as  affected  by  the  Natural  Conditions  of  Existence. 
By  KARL  SEMPER,  Professor  of  the  University  of  Wiirzburg.     With 
2  Maps  and  106  Woodcuts,  and  Index.     12mo.    Cloth,  $2.00. 
"This  is  in  many  respects  one  of  the  most  interesting  contributions  to 

zoological  literature  which  has  appeared  for  some  time."— Mature. 

THE  ATOMIC  THEORY.  By  AD.  WURTZ,  Membre  de  1'Institut ; 
Doyen  llonoraire  de  la  Faculte  de  M6decine ;  Professeur  a  la  Facult6 
des  Sciences  de  Paris.  Translated  by  E.  CLEMINSHAW,  M.  A.,  F.  C. 
S.,  F.  I.  C.,  Assistant  Master  at  Sherborne  School.  12mo.  Cloth, 
$1.50. 

"There  was  need  for  a  book  like  this,  which  discusses  the  atomic  theory  both 
in  its  historic  evolution  and  in  its  present  form.  And  perhaps  no  man  of  this 
age  could  have  been  selected  so  able  to  perform  the  task  in  a  masterly  way  as 
the  illustrious  French  chemist,  Adolph  Wnrtz.  It  is  impossible  to  convey  to  the 
reader,  in  a  notice  like  this,  any  adequate  idea  of  the  scope,  lucid  instruct!  veness, 
and  scientific  interest  of  Professor  Wurtz's  book.  The  modern  problems  of 
chemistry,  which  are  commonly  so  obscure  from  imperfect  exposition,  are  here 
made  wonderfully  clear  and  attractive." — The  Popular  Science  Monthly. 

THE  CRAYFISH.  An  Introduction  to  the  Study  of  Zoology.  By 
Professor  T.  H.  HUXLEY,  F.  R.  S.  With  82  Illustrations.  12mo. 
Cloth,  $1.75. 

"  Whoever  will  follow  these  pages,  crayfish  in  hand,  and  will  try  to  verify  for 
himself  the  statements  which  they  contain,  will  find  himself  brouirnt  face  to  face 
with  all  the  great  zoological  questions  which  excite  so  lively  an  interest  at  the 
present  day." 

"The  reader  of  this  valuable  monograph  will  lay  it  down  with  a  feeling  of 
wonder  at  the  amount  and  variety  of  matter  which  has  been  got  out  of  so  seem- 
ingly slight  and  unpretending  a  subject."— Saturday  Review. 


New  York :    D.  APPLETON   &   CO.,  1,  3,  &  6  Bond  Street. 


D,  APPLETON  &  00,'S  PUBLICATIONS, 

THE    ORIGIN   OF   THE    FITTEST:    ESSAYS   ON   EVOLU- 
TION.    By  Professor  E.  D.  COPE,  Member  of  the  National  Academy 
of  Sciences.     With  numerous  Illustrations.     8vo,  cloth.     $3.00. 
CONTESTS  :  Part  I.  General  Evolution.     Part  II.  Structural  E  mlencq  of 
Evolution.      Part  III.    Mechanical    Evolution.       Part  IV.    Metaphysical 
Evolution. 

Probably  no  scientist  in  the  United  States  is  of  higher  authority  in  the  field 
covered  by  this  volume  than  Professor  Cope,  whose  paleontologies!  discoveries 
have  made  him  famous  in  scientific  circles  in  Europe  as  well  as  in  America.  The 
twenty-one  essays  which  constitute  the  work  present  the  whole  subject  of  evolu- 
tion with  great  fullness. 

A  TREATISE  ON  SURVEYING,  COMPRISING  THE  THEORY 
AND  THE  PRACTICE.  By  WILLIAM  M.  GILLESPIE,  LL.  D.,  for- 
merly  Professor  of  Civil  Engineering  in  Union  College.  Revised 
and  enlarged  by  CADY  STALEY,  Ph.  D.,  President  of  Case  School  of 
Applied  Science.  With  numerous  Illustrations.  8vo,  half  bound. 
$3.50. 
The  two  volumes  previously  published,  "Land  Surveying"  and  "Leveling 

and  Higher  Surveying,"  are  now  revised  and  united  in  this  volume. 

THE  SUN.  By  C.  A.  YOUNG,  Ph.  D.,  LL.  D.,  Professor  of  Astronomy 
in  the  College  of  New  Jersey.  With  numerous  Illustrations.  Third 
edition,  revised,  with  Supplementary  Note.  Vol.  34  of  "  The  Interna- 
tional Scientific  Series."  12mo,  cloth,  $2.00. 

In  this  edition  a  "  Supplementary  Note  "  has  been  added,  giving  a  brief  state- 
ment of  the  most  important  developments  in  eolar  astronomy  since  the  publica- 
tion of  tlie  second  edition,  in  1882,  bringing  the  subject  to  date  as  lar  as  possible. 
"  Professor  Young  is  an  authority  on  '  The  Sun.'  and  writes  from  intimate 
knowledge.  He  has  studied  that  great  luminary  all  his  life,  invented  and  improved 
instruments  far  observing  it,  gone  to  all  quarters  of  the  world  in  search  of  the 
best  places  and  opportunities  to  watch  it,  and  has  contributed  important  discov- 
eries that  have  extended  our  knowledge  of  it."— Popular  Science  Monthly. 

THE  POISON  PROBLEM ;  OR,  THE  CAUSE  AND  CURE  OF 
INTEMPERANCE.  By  FELIX  L.  OSWALD,  M.  D.,  author  of  "  Physi- 
cal Education."  New  cheap  edition.  12mo.  Paper,  25  cents. 

"  The  most  forcible  exposition  of  the  evil  of  intemperance  that  has  lately  been 
published.  It  contains  facts  derived  from  recent  statistics,  and  the  views  of  meu 
of  science  on  the  terrible  results  of  the  use  of  alcohol  in  all  parts  of  the  world." 
—Philadelphia  Bulletin. 

A  NEW  PHYSICAL  GEOGRAPHY.  By  E^ISEE  RECLTJS. 
Being  Supplementary  Volumes  to  M.  RECLUS'S  "  Earth  and  its  In- 
habitants." Edited  by  A.  H.  KEANE,  B.  A.  In  two  volumes.  Illus- 
trated by  numerous  Engravings,  and  by  Maps  printed  in  Tints. 

Vol.   I.  The  Earth :   A  Descriptive  History  of  the  Phenomena  of  the  Life 

of  the  Globe. 
Vol.  II.  The  Ocean,  Atmosphere,  and  Life. 

Price,  per  Volume,  $6.00  in  sheep ;  $7.00  in  half  Morocco. 


New  York :  D.  APPLETON  &  CO.,  1,  3,  &  5  Bond  Street. 


D.  APPLETON  &  00,'S  PUBLICATIONS, 


PHYSICAL  EXPRESSION:  Its  Modes  and  Principles.     By 

FRANCIS  WAR.NKR,  M.  D.,  Assistant  Physician,  and  Lecturer  on  Bot- 
any, to  the  London  llospital,  etc.     With  51  Illustrations.     12mo. 

f  Cloth,  $1.75. 

"  In  the  term  '  Physical  Expression,'  Dr.  Warner  includes  all  those  changes  of  form 
and  feature  occurring  in  the  body  which  may  be  interpreted  as  evidences  of  mental 
action.  At  first  thought  it  would  seem  that  facial  expression  is  the  most  important 
ot  these  outward  signs  of  inner  processes;  but  a  little  observation  will  convince  one 
that  the  posture  assumed  by  the  body  — the  poise  of  the  head  and  the  position  of  the 
hands— as  well  as  the  many  alternations  of  color  and  of  general  nutrition,  are  just  as 
striking  evidences  of  the  course  of  thought.  The  subject  thus  developed  by  the  au- 
thor becomes  quite  extensive,  and  is  exceedingly  interesting.  The  work  is  fully  up 
to  tha  standard  maintained  in  •  The  International  Scientific  Series.'  "—Science. 

u  Among  those,  besides  physicians,  dentists,  and  oculists,  to  whom  Dr.  Warner's 
book  will  be  of  benefit  are  actors  and  artists.  The  art  of  gesticulation  and  of  postures 
is  dealt  with  clearly  from  the  scientific  student's  point  of  view.  In  the  chapters  con- 
cerning expression  in  the  head,  expression  in  the  face,  expression  in  the  eyes,  and  in 
that  on  art  criticism,  the  reader  iuay  find  many  new  suggestions."— Philadelphia 
fret. 

COMMON   SENSE   OF   THE    EXACT   SCIENCES.      By  th? 

late    WILLIAM    KINGUON    CLIFFORD.      With    10O.  Figures.      12mo. 
Cloth,  $1.50. 

"  This  is  one  of  the  voTnmes  of  '  The  International  Scientific  Series,1  and  wan  origi- 
nally planned  by  Mr.  Clifford;  but  upon  his  death  in  Ib7i»  the  revision  and  completion 
of  the  work  were  intrusted  to  Mr.  C.  R.  Rowe.  He  also  died  before  accomplishing  his 
purpose,  and  the  book  had  to  be  finished  by  a  third  person.  It  is  divided  into  five 
chapters,  treating  number,  space,  quantity,  position,  and  motion,  respectively.  Each 
of  these  chapters  is  subdivided  into  sections,  explaining  in  detail  the  principles  under- 
lying each.  The  whole  volume  is  written  in  a  masterful,  scholarly  manner,  and  the 
l  ire  illustrated  by  one  hundred  carefully  prepared  figures.  To  teachers  espe- 
cially is  this  volume  valuable;  and  it  is  worthy  of  the  most  careful  study ."—Aew  York 
School  Journal. 

JELLY-FISH,  STAR-FISH,  AND  SEA-URCHINS.  Being 
a  Research  on  Primitive  Nervous  Systems.  By  G.  J.  ROMANES, 
F.  R.  S.,  author  of  "Mental  Evolution  in  Animals,"  etc.  12mo. 
Cloth,  $1.75. 

44  A  profound  research  into  the  laws  of  primitive  nervous  systems  conducted  by  one 
of  the  ablest  Knglish  investigators.  Mr.  Romanes  set  up  a  tent  on  the  beach  and  ex- 
amined his  beautiful  pets  for  six  summers  in  succession.  Such  patient  and  loving 
work  has  borne  its  frnits  in  a  monograph  which  leaves  nothing  to  be  said  about  jelly- 
fish, star-fish,  and  sea-urchins.  Every  one  who  has  studied  the  lowest  forms  of  life  on 
the  sea-shore  admires  these  objects.  But  few  have  any  idea  of  the  exquisite  delicacy 
of  their  structure  and  their  nice  adnptation  to  their  place  in  nature.  Mr.  Romanes 
brings  out  the  subtile  beauties  of  the  rudimentary  organisms,  nnd  shows  the  resem- 
blances they  bear  to  the  higher  types  of  creation.  His  explanations  are  made  more 
clear  by  a  large  number  of  illustrations.  While  the  book  is  well  adapted  for  popular 
reading,  it  is  of  special  value  to  working  physiologists."— Ifew  York  Journal  oj 
Commerce. 

"  A  most  admirable  treatise  on  primitive  nervous  svstems.  The  subject-matter  is 
full  of  original  investigations  and  experiments  upon  the  animals  mentioned  as  types 
of  the  lowest  nervous  developments."— Boston  Commercial  Bulletin. 


New  York:   D.  APPLETON  &  CO.,  1,  3.  &  5  Bond  Street, 


D.  APPLETON  &  CO.'S  PUBLICATIONS, 


BRAIN  EXHAUSTION,  with  some  Preliminary  Considerations  on 
Cerebral  Dynamics.  By  J.  LEONARD  CORNING,  M.  D.,  formerly  Resi- 
dent Physician  to  the  Hudson  River  State  Hospital  for  the  Insane. 
Crown  8vo,  cloth,  $2.00. 

"The  author  begins  by  laying  a  broad  foundation  for  his  deductions  in  con- 
sidering the  law  of  the  convertibility  of  forces  to  the  dynamics  of  the  brain.  This 
parallelism  between  inanimate  physics  and  cerebral  action  is  closely  followed  by 
our  author,  and  with  excellent  results.  Dr.  Corning  proceeds  to  classify  his  facts, 
which  appear  to  be  drawn  from  wide  experience  and  study,  and  to  marshal  them 
with  the  bkill  of  a  trained  scientist.  He  first  considers  the  various  existing  causes 
which  conduce  to  brain  exhaustion  in  the  physical  sense,  such  as  alcohol-drink- 
ing, tobacco,  excessive  sexualism,  irregular  hours,  etc. ;  in  the  mental  sense, 
overwork,  whether  iu  study  and  business,  fret  and  worry,  false  educational  meth- 
ods, etc.  He  concludes  with  a  summary  of  the  principles  of  brain  hygienics,  and 
indicates  very  clearly  how  brain  exhaustion  may  be  remedied  before  the  final  and 
inevitable  result  comes.  In  these  latter  chapters  the  author  discusses  the  relation 
of  blood  to  muscle  and  brain,  the  relation  of  food  to  mental  phenomena,  rest, 
special  medication,  etc.  The  book  is  admirably  written.  The  style  is  simple, 
tnrect,  lucid,  with  as  much  avoidance  as  possible  of  technical  terms  and  purely 
professional  logic.  It  is  a  timely  work,  which  every  thinking  man  can  read  with 
interest  without  being  a  physician.  Brain-workers  everywhere  can  study  this 
able  digest  with  both  profit  and  pleasure."— Eclectic  Magazine. 

OUTLINES  OF  PSYCHOLOGY,  with  Special  Reference  to  the 
Theory  of  Education.  A  Text-Book  for  Colleges.  By  JAMES  SULLY, 
A.  M.,  Examiner  for  the  Moral  Sciences  Tripos  in  the  University  of 
Cambridge,  etc.,  etc.  Crown  8vo,  cloth,  $3.00. 

41 A  book  that  has  been  long  wanted  by  all  who  are  engaged  in  the  business  of 
teaching  and  desire  to  master  its  principles.  In  the  first  place,  it  is  an  elaborate 
treatise  on  the  human  mind,  of  independent,  merit  as  representing  the  latest  and 
best  work  of  all  schools  of  psychological  inquiry.  But  of  equal  importance,  and 
what  will  be  prized  as  a  new  and  most  desirable  feature  of  a  work  on  mental 
science,  is  the  educational  applications  that  are  made  throughout  in  separate  text 
and  type,  so  that,  with  the  explication  of  mental  phenomena,  there  comes  at  once 
the  application  to  the  art  of  education." 

BODY  AND  WILL :  being  an  Essay  concerning  Will  in  its  Meta- 
physical, Physiological,  and  Pathological  Aspects.  By  HENRY 
MAUDSLEY,  M.  D.  8vo,  cloth,  $2.50. 

"  Dr.  Mandslpv's  powers  of  losric  have  never  been  more  keenly  exercised  than 
in  'Body  and  Will,1  bis  latest,  volnme.  He  takes  the  ultra-materialistic  view  of 
the  human  mind,  and  regards  will  as  the  result  of  definite  material  causes,  so 
that,  were  synthetical  science  a  little  further  advanced,  it  would  be  possible, 
havino-  given  physical  conditions,  to  declare  the  inevitable  resnlt.  The  skill  and 
erudition  displayed  in  'Body  and  Will'  are  only  equaled  by  the  keenness  of  its 
criticisms  npon  what,  from  the  writer's  point  of  view,  are  empirical  dn<rmap. 
No  fairer  or  more  able  exposition  on  the  latest  scientific  teaching  upon  the  sub- 
ject of  man  as  a  free  agent  is  to  be  found  than  in  this  volume."— .Boston  Courier. 


New  York :  D.  APPLETON  &  CO.,  1,  3,  &  5  Bond  Street. 


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