“

ALBERT R. MANN
LIBRARY

NEw YORK STATE COLLEGES
OF
AGRICULTURE AND HOME ECONOMICS

AT

CORNELL UNIVERSITY

IT

The original of this book is in
the Cornell University Library.

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http://www.archive.org/details/cu31924000659122

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INSTITUTED MDCCCXLIV.

LONDON.

MDCCCLITT,

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BOTANICAL AND PHYSIOLOGICAL

ee
MEMOIRS,

CONSISTING OF

L—THE PHENOMENON OF REJUVENESCENCE IN NATURE,
ESPECIALLY IN

THE LIFE AND DEVELOPMENT OF PLANTS.
te

BY DR. A. BRAUN. . /

TRANSLATED BY A. HENFREY, F.R.S., ETC.

IL—ON THE ANIMAL NATURE OF THE DIATOMEA,
WITH AN

ORGANOGRAPHICAL REVISION OF THE GENERA

ESTABLISHED BY KÜTZING.

BY PROFESSOR G. MENEGHINI.

TRANSLATED BY CHRISTOPHER JOHNSON, M.R.C.S.E.

IL—AN ABSTRACT OF THE NATURAL HISTORY OF PROTOCOCCUS
PLUVIALIS.

BY DR. FERDINAND COHN.

BY GEORGE BUSK, F.R.S., ETC.

ARTHUR HENFREY, F.R.S., F.L.S.
LONDON:

PRINTED FOR THE RAY SOCIETY.
MDCCCLIIT.

318161

uF. ADLARD, PRINTER, BARTHOLOMEW CLOSE.

CONTENTS.

On THE PHENOMENON OF REJUVENESCENCE IN NATURE . 3 1
» ANIMAL NATURE OF THE DIATOMER . R 343
515

NATURAL History oF PROTOCOCCUS PLUVIALIS . #

Bry

REFLECTIONS

ON

THE PHENOMENON

OF

REJUVENESCENCE IN NATURE,

ESPECIALLY IN

THE LIFE AND DEVELOPMENT OF PLANTS.

By Dr. ALEXANDER BRAUN,

PROFESSOR OF BOTANY IN THE UNIVERSITY OF BERLIN,
&c. &c.

(Leırsıc, 1851.)

TRANSLATED BY

ARTHUR HENFREY, F.R.S., F.L.S., Ere.

TO THE READER.

Tue present ‘Treatise ‘On the Phenome non of Rejuvenes-
cence in Nature, especially in the Life and Development
of Plants,’ was issued to a small circle in May of last
year, from the High School of Freiburg, in the Breisgau,
to which the Author at that time belonged, and for which
it was especially composed, as a Prorectorate Address ;
its publication to wider circles of the Scientific world
has been delayed by many circumstances, partly connected
with the change of residence of the Author, through his
call to the High School of Giessen ; partly in consequence
of the events which afflicted the country with dissensions,
and obstructed the calm progress of scientific undertak-
ings. Nevertheless, the Author hopes that the substance
of the Essay, which contains an attempt to combine the
special branches of Botanical research more intimately
together and with the entire body of Science, by means
of certain connecting ideas, and to grasp and trace out
the old questions under a new point of view, has not
meanwhile grown out of date, so that he may venture to
comply with friendly requisitions from many quarters, and

x PREFACE,

deliver over his little work to more general diffusion.
May the reader receive it kindly, as a little nail in the
great structure which Natural Science has to erect, to
which each labourer seeks to add his contribution in his
own way, and to work for which, with voice and pen,
is the endeavour, the life, and the happiness of the
Naturalist
THE AUTHOR.

Giussen ; February, 1851.

Since the original of this work was published, the
Author has been chosen to succeed the late Professor
Link in the University of Berlin; and now occupies a
position commensurate with his numerous and elaborate
contributions to Science. Modestly as he speaks of this
remarkable work, the Translator has no hesitation in
designating it one of the most important of modern con-
tributions to the Philosophy of Botany. Without enter-
ing into the discussion of the curious speculations
indicated in the title, attention is especially to be called to
the lucid exposition of the Morphology of Plants, and to
the definite establishment and full illustration of the laws
of this branch of botanical science; to the section upon
Cell-formation, again, which constitutes a body of fact
and theory of the utmost importance to Physiology,
Animal as well as Vegetable, since, bringing together
and completing the various recent publications on the

PREFACE. xl

subject of cell-development, it clearly demonstrates the
necessity of reforming the older views of the character of
cellular structures, and, in showing the incontestible
evidence now existing as to the essentially primary nature
of the cell-contents or protoplasmic structures, at once
levels the new field of investigation in Plants, and affords
a basis for the clearing up of the analogies existing
between the Animal and Vegetable tissues.

The Translator has confined himself to a careful
rendering ofthe text and a slight amplification of the refer-
ences, especially in cases where English translations exist
of the works quoted. To have revised, in accordance
with the present condition of knowledge, certain of the
speculations which are now a little out of date, would
have been interfering too far with the Author; but the

sources are indicated whence the more recent facts may
be obtained.

A.H.
Lonpon ; September, 1853.

SUMMARY OF THE CONTENTS.

PAGE

Prerace: Origin and object of the Treatise, with addenda to certain
special parts . :

Inrropuction: Reflections on the appearance ail the Sante Nature
of Rejuvenescence in general; passing to the Phenomena of Reju-
venescence in Plants, more particularly, divided into three sections

1. Formation or Sprouts as the means of Rejuvenescence of the
Vegetable stock
1. Individual nature of the Sprouts
2. Formation of sprouts as subordinate beprodustiin, and aller
nation of generations of the plant caused thereby
a. Origin of sprouts
b. Deficiencies of them .
c. Complementary conditions
d. Distinction of essential and inessential sprouts
e. Importance of the latter in reference to
a Character a :
ß Economy of Vegetable life .
J. Transitional cases :

11. LEAF-FORMATION, giving rise to the subdivisions of the Rejuvenes-
cence in the single sprout :
1. Phenomena of Rejuvenescence in the aprout chreugli retro
gressive and vibratory course of the Metamorphosis
9. The ascending Metamorphosis considered in its risings and
sinkings
a. Summary ai the Leaf- cannitions
b. Change of proportionate breadth of the base of the
leaf in the different leaf-formations
c. The samein the longitudinal development of the leet,
d. Disappearance of leaf-formation in particular regions.
3. The individual leaves as links of Rejuvenescence in the course
of Metamorphosis

ix

101

XIV

CONTENTS.
PAGE

a. Criticism of Schultz’s doctrine of the Anaphyta of
the plant . 102
d. Criticism of E. Meyer’s and aller views of the building
up of the plant out of leaves ; and also of Steenstrup’s
view of the Alternation of Generations in the plant 106

ce. Relation of the stem to leaf-formations . . 108
Explained by the examination of the fundamental
organs of the plant i 5 . 109
d. Course of formation of the leaf . ‘ .112
e. Observations on Phyllotaxy a ‘ . 116
111. CELL-FORMATION, constituting the immediate focus of the pheno-
mena of Rejuvenescence : : . 121
1. Formation of the Cell, sent . 123
a. Departure of the plant and of the Vegetuble kingdom from
the simple cell e . 124
a, Unicellular nn in the different senses of the
term . 124
8. Graduated succession of Multi. edllular plants . 130
b. The single cell, examined by itself . i . 155
a. The various meanings of the word Cell . . 155
8. Membrane and contents of the Cell : . 155
y. Cells without membrane i . 156
6. Coat of the contents pvimnonitial utricle) . . 156
&. Further subdivision of the contents ‘ . 169
« Nucleus. . 174
2. Destruction of the Cell, a preparatory © condition to its Bafa
venescence B . 176
A. The Cell-membrane . 3 ‘i . 176
a. Dissolution of this e 4 = 177
a. Through tearing 177

ß. Through complete peeling (Sidubitig of the cell) 180
y. Escape of the Rejuvenescent cell from the
old coat (demonstrated more particularly in

the active gonidia of the Alye) ; . 182

6, Examples of imperfect liberation of gonidia . 187

8. Softening and Solution of the Cell-membrane . 189
». Processes of Destruction in the contents of the cell 195
w. Solution of Starch . ‘ ‘ . 196
6. Disappearance of Fat. 5 : . 202
Caused by previous desiccation . . 205

(Illustrated by the history of Chlamidococeus aul
Chlamidomonas) . ; ‘ . 205

CONTENTS.

XV

PAGE

e. Relation of these phenomena to the interchange of
substances in animals
d. The nocturnal respiration of plants
e. The phenomenon of Rejuvenescence of the Cell in
its relation to the periods of the day .
3. Reconstruction of the Cell, considered as a process of Rejuve-
nescence
Kind and degree of Rasonstruetion :
A. Reconstruction without division of the cell
B. With division into two Daughter-cells :
(Different descriptions of this by Mohl, Unger, and Nägeli)
a. Division by gradual constriction (confirmed in Spi-
rogyra)
d. Division with Snellansoni (e) ietiagion over the
whole plane of division
B*, Reconstruction with division into two cells, one srenatiiog
as an unchanged Mother-cell, the other cut off as a
Danghter-cell (cell-formation by constriction).
c. Reconstruction with division into four Daughter-cells
Connection of this with halving
D. Reconstruction with division into an indefinite Amber of
Daughter-cells :
1, By division of contents filling fie whole ori of the
cell
2. By division of a layer of Korte gene. the wall of
the Mother-cell (explained specially in Hydrodictyon)
Connecting case
=. Partial Reconstruction through (nestor of Daaahtans cells
inthe contents of theindependently surviving Mother-cell
1. The Daughter-cells produced close upon the cell-wall
2. The Daughter-cells formed free in the contents
a. Formation of a free Daughter-cell around the pri-
mary nucleus of the Mother-cell
4. Formation of free Daughter-cells around secondary
nuclei ‘
a, Formation of the Se vesicles of the Pha-
nerogamia
8. Of the transitory cells in the anbrye! sac
y. Of the endosperm cells
ö. Cases of abnormal cell-formation
4, Appendix, on the union of a mr Cells (Con-

jugation)

. 217
. 219

. 221

. 226

. 229
. 232

233

. 237
. 247
. 250
. 254
. 256

. 259

. 259

261

.271

272
272

. 274

. 275

. 276

. 276

. 278
. 278

. 281

. 281

XV1 CONTENTS.

PAGE
Attempt to classify the numerous kinds of Conjugation :
A. Conjugation of Similar cells, with the subordinate modif-
cations 284
B. Conjugation of Dissimilar cells . 296
Excluded cases . . 298
305

Conciupine RRFLECTIONS .

Connection of the Tieivenevoenee of the Individual with that of
the Species - 306

a. Examination of the ehachehien of Ehe anges and Ferns
in reference to this . 808

4. The formation of Varieties, in its felusion to the history of
the Individuals and of the Species . . 311

c. Examination of Hybrids (with a particular deinen of
the behaviour of Cytisus Adami) . . 316

2. Analogous ascent in the higher systematic Ginistous; from
the species to the genus, family, order, class, &e. . . 822

3. Rejuvenescence as universal Phenomenon of the course of De-

velopment of Nature, in detail and as a whole, as the expres-

sion of a constantly re-awakened recollection ofthe inherent

Vital Purpose. ‘ 4 324
EXPLANATION OF THE PLATES 327
InpEx . ¥ ; ‘ ‘ 337

ADDENDUM. At page 9, line 5, insert after

“ Rheum with 6, outer, shorter, and 3 inner, longer ;” “in Polygonum
with 5, outer, shorter, and 3 inner, longer.”

PREFACE.

Tax idea carried out in the following treatise, namely,
of grouping together the phenomena of the graduated
organisation of plants, and those of their reproduction,
under a common point of view, as processes of Rejuvenes-
cence, and of subjecting them to a minute examination
under this point of view, was awakened in my mind several
years ago, through an investigation of Hydrodictyon, and
aroused anew at the end of that autumn of 1848 through
the discovery of the mode of reproduction of Pediastrum,
a genus of most elegant little Algee, which are still
included by many authors in the Animal Kingdom. At
the Annual meeting of our local Association for the ad-
vancement of the Natural Sciences, on the 4th of December
of the same year, I endeavoured, in a public lecture,
apropos to the description of the course of formation and
reproduction of the genus of Algze just named, to develope
this idea, and to show that it is the power of Rejuvenes-
cence which principally distinguishes organic from inor-
ganic existence, since it is to this that we must ascribe,
both the graduated progression of the development of the
individual organism, and the repetition of individuals
by reproduction. When in the spring of last year, the

confidence of my colleagues, and the grace of his Royal
b

xvil PREFACE.

Highness the Grand-Duke, the most serene Rector of
our High School, conferred the Prorectorate upon me, I
determined to make this subject, which appeared both
capable of a profound treatment and of general interest,
the basis of the Introductory Programme which, in
accord nce with the good old custom, the Prorector
“lists in honour of the birthday of the exalted Patron
aud Rector of the High School, our beloved native
Prince. The main thoughts were soon arranged, and
the outlines traced; the illustrative examples added to
the text were to be worked out during the printing of
the essay, and the natural history of some of the genera
of Algze more particularly remarkable in reference to the
subject, (Pediastrum, Characium, Hydrodictyon, As-
cidium, Sciadium, Palmoglea, &c.) was to be given in an
appendix. But the storm of the revolution, which broke
out in May, and shook our blessed fatherland to the
very foundations of its existence, soon interrupted the
incipient labours ; for our High School was threatened
by the tempestuous waves, and it was at the cost of care
and severe effort alone, that the threadsof scientific activity
were protected from total disruption in the midst of
the session. But, in the ever-memorable days of July,
when the fermenting elements of social dissolution, which
we at length saw gathered within our walls, had vanished
before the helpful Brother-hand, strong in the spirit of
order, like the shades of night before the sun’s light ;
when in the following month our beloved ruler was
enabled to return to his blinded people, who, ungrateful
for his beneficence, had risen in opposition to him; the
season was too far advanced, for the projected discourse
to be properly carried out in time, on the basis which

PREFACE. xix

had been previously laid down. Consequently, to avoid
offering anything hasty and unworthy of the High School,
and yet to avoid withdrawing this essay from the des-
tination to which it had been as a labour of love devoted,
there remained nothing else, but to make it follow the
invitation to the celebration of the Royal birthday, as a
subsequent secondary tribute. The reasons why it has
been delayed until now, lie partly in the manifold re-
tardations through current official duties, and partly in the
nature of the subject itself, which claimed more time
and space in the elaboration of the details, than could be
guessed in the original project. For, in the publica-
tion of phenomena as yet little known, the examples
cited could not well be mentioned without an exact
account of personal observations, which rendered neces-
sary repeated diffusive episodes, in which both the vo-
taries of the Morphology and Anatomy of Plants, and
Physiologists in particular, will find many novelties.
Where I have depended on the observations of others,
the sources are conscientiously mentioned; I connected
with this point also the design, to point out to the young
who are just entering the realms of Science, who, more-
over, were especially kept in view throughout the whole
exposition of the chosen subject, the authors who deserve
confidence, and from whose writings may be discerned,
not only the present state of Scientific Botany, but the
problems growing out of this, which will next require
to be solved. I had greatly desired to be able to add
numerous illustrative plates to this treatise, but I have
omitted doing so, in order to avoid further delaying its
publication. For the same reason I am obliged to give
up, for the present, the appendix which formed part of

XX PREFACE.

the original plan, and which is referred to more than
once in the text; a separate treatment of this will the
sooner enable me to publish, with a certain degree of
completeness, my observations on the natural history
of various fresh-water Alge, in particular on many genera
belonging to the debateable region between the Veget-
able and Animal Kingdoms, as well as those that
produce active gonidia.

After these remarks, which may explain the delay in
the appearance of these pages, I feel compelled to add
a word of justification in reference to the direction of the
researches which form the basis of the following obser-
vations, and which will doubtless be regarded in many
quarters as antiquated, and leading away from the strict
scientific path. A vivid conception of Nature, such as
is here attempted, which tries to find in natural objects,
the expression of living action, and not merely the effects
of dead forces, does not lead, as some think, to baseless
air-castles, for it does not set itself to study the life of
nature, in any other way than in its revelation through
phenomena; and just as little does it exclude rigid in-
vestigation of the laws, governing all natural phenomena ;
for it is exactly by the investigation of the laws within
which, and the forces through which life acts, that it
hopes to arrive at a perception of what is given to life,
according to the difference of its stages. The justification
of the effort to comprehend all the phenomena of nature,
not only in their external reactions, but also in their
inner connection, as the data for an universal history of
living nature, lies in the very nature of the human soul,
in its connection, not merely external but inward and
essential, with living nature. As the study of nature

PREFACE, xxl

originally arose from the feeling of the intimate relation-
ship between external nature and human nature, it is
also its aim to grasp and bring to perception, the fur-
thest depths of this connection.

Partly during the printing of these pages, partly after
its conclusion, I met with various literary novelties, of
which I could have wished to have availed myself in
passages on which they bore, in particular, Mettenius’s
‘ Beiträge zur Botanik’ (Heidelberg, 1850), in which
occurs an exact description of the discovery of spermato-
zoids in Jsoétes, mentioned cursorily at page 144 from
information derived from a letter from the author.*
Geertner’s important work, on the Production of hybrids in
the Vegetable Kingdom, (Die Bastardzeugung im Pflan-
zenreich, Stuttgart, 1849), first reached me after my ob-
servations on Cytisus Adami, p. 316, were printed. There
is no absolute decision there even, whether this remarkable
intermediate species is a hybrid, produced by fertilisation
from Cyt. Laburnum, and C. purpureus, or not; on the
other hand various notices on the same subject had been
published, which I had overlooked, especially the informa-
tion of Schnittspahn’s paper, in the third Year’s publication
of the Horticultural Society of the Grand-duchy of Hesse,
(Mitth. des Gartenvereins im Grossherz. Hess., Darmstadt,
1842, p. 38,) that Adam obtained his plant, by budding
C. purpureus upon C. alpinus.t During the first year
the grafted buds remained undeveloped, but many ine-
qualities of the surface displayed themselves around

* These points are further referred to in editorial notes.—A. H.

T This probably means C. alpinus, Lamk., the same as C. Laburnum, L.,
and not C. alpinus, Mill., for the C. Adami of gardens returns on all hands
into €. Laburnum, L., and not into C. alpinus, Mill.

XX11 PREFACE.

them, which were gradually developed into buds, and these
were developed in the second year into shoots, all but
one of which, were C. purpureus. This one shoot had
grown much thicker, and exhibited a form intermediate
between C. alpinus and C. purpureus; this shoot was the
parent of the C. Adami of gardens. Unfortunately, this
report does not state from what source H. Schnittspahn
himself derived his knowledge of these circumstances at-
tending the origin of C. Adami. Since C. Adam: possesses
undoubtedly the nature of a hybrid, if Schnittspahn’s
information be correct, this plant will furnish the ex-
traordinary case of a hybridation in a vegetative way,
(conceivable as occurring through a fertilising action of
the cells of the graft upon the primitive cell of an adven-
titious bud,) and its return into the two parent species,
within the vegetative region, would then correspond to
the vegetative origin. That hybridation is not in any
way unusual in the genus Cytisus, is proved by a mag-
nificent hybrid, between C. purpureus and C. elongatus,
which is now, while I write these lines, in most beautiful
blossom in the Botanical garden of our High School.
It was obtained from the brothers Baumann of Bollwiller,
in whose catalogue for 1847, it is given as “C. purpureo-
elongatus (nobis), une nouvelle hybride superbe.’ In
form and hairiness of the leaves it resembles C. elongatus;
in the form of the calyx, more C. purpureus. The colour
of the flowers is a mixture of light-yellow and pale rose-
red, the standard being of the latter colour, the wings
and keel of the former; when withered or dry, the red
colour becomes stronger and almost like that of Cytisus
Adami. The blossoms keep fresh a long time, but set no
fruit. Messrs. Baumann were kind enough to furnish

PREFACE. xx

me, by letter, with the following particulars concerning
the origin of this fine hybrid. “ Our C. purpureo-elongatus
was produced from our own sowing, but not by means
of artificial fertilisation ; the mother of this plant is C.
elongatus, from which we gathered the seeds; but near
this stood a C. purpureus, and probably the hybrid was
produced by insects conveying the pollen from the latter
plant to the former. We have never observed in this
plant such a change of form as occurs in C. Adami.”
After all this, we look with so much the greater impa-
tience for positive elucidation, based on repeated experi-
ments, of the mode of origin of C. Adami, and in this
for the establishment of several most important physiolo-
gical facts. In regard to the return of Cytisus Laburnum
quercifolius, into the common Laburnum with entire
leaflets, mentioned at p. 315, I shall only mention here,
in addition, that I have observed the same phenomenon
lately in the Botanic garden of this town, and here the
transition to the parent species took place by a marked
separation from the variety and not through graduated
intermediate stages.

Since this Preface is at the same time a Postscript, and
as regards the first part of the Treatise a tolerably late one,
it affords an opportunity of adding a few more comple-
mentary observations on the subjects touched upon in
the text. In the first place, in regard to the mode of growth
of the Vine, described at p. 46, I must report that the
examination of fresh seedlings obtained last autumn, after
that passage had been printed, did not confirm the con-
jecture expressed in the note, that the seedlings would
behave like root-suckers ; for they were totally devoid of
tendrils at the summit, and displayed in the axils of the

=

XXIV PREIACE.

ordinary leaves, resting buds, which had {wo bud-scales,
and therefore resembled,in this respect, not the “Geitzen,”
but the “ Zoften.” The derivation of the “Zot¢en” from
the “Geitzen” in the way described, does not occur
until the later degrees of ramification.

To the examples mentioned in the note, p. 114 of Fern
leaves, with the apex of the leaf constantly undeveloped, or
only unrolled after long interspaces and in steps, belongs
also the genus Neurolepis, the larger species of which, re-
lated to N. ewaltata, develope their slender pinnate leaves,
which often attain a length of 4 or 5 feet, in several
annual stages or lengths, which are marked in the deve-
loped leaf as contracted places, furnished with shorter
pinne. In N. neglecta, Künze., the commonest species
of our gardens, I found four such sections, of which,
however, two often appear to be developed in one year.
With this mode of development is connected the fact
that the leaves of the species of Mewrolepis ordinarily exhibit
a little rolled-up knob at the end, and only rarely their
proper leaf-point, running out into a terminal pinna.

I have to give a short postscript to the natural history
of the Chlamidomonada, relating to the “resting stage”’ of
Chlamidomonas tingens (p. 215). The said species
appeared in great abundance this spring in little rain
pools, close to the town, colouring the water bright green.
When the “rest” commenced, the cells collected together
in pulverulent, partly floating masses, exhibited a
globular form, a diameter of from „to 4 of a millim.,
granular-punctate, green contents, and one ‘larger vesicle.
When the pools dried up in the month of May, crust-
like, pale brick-red coats were found on the ground, the

cells, formerly green, having assumed a pale reddish

PREFACE. XXV

colour, the vesicle at the same time becoming indistinct,
while the remainder of the contents became coarsely
granulated, (through the formation of oil?). The plants
have remained in this state ever since, not altering even
when the pools were refilled by rain. The resting, but
still green condition, seemed to me to correspond to
Protococcus Felisii, Kütz., that which had turned red
through desiccation, to Pr. Orsinü, Kütz., at least, ac-
cording to the specimens sent to me by De Brébisson
as a small variety of that species.

Herewith, I deliver these pages to the Fathers of our
High School, my honoured colleagues, with the petition
for a friendly reception, as a memorial of the efforts and
expansions in Science and in Life, we have shared in an
eventful year; I deliver it to the Academic Youth, in
the hope that they may find therein the threads which
connect the separate fragments of knowledge into a
whole, and that the perception of this connection may
encourage them to follow, with double zeal, undistracted,
through good and evil times, the study of the material
so abundant in all branches of science, and thus to enter
more and more into the sacred workshops, in which are
hewn the stones for building the great Dome of human
knowledge. To the wider scientific public, lastly, I
delive: these pages, with the consciousness of having
therein published many results of conscientious research
which will find their place in the building of Science,
even if the connection in which I have here sought to
place them, should shape itself very differently in a
future, higher stage of development of Natural History

Dr. A. Braun.

FREIBURG, Brrescau; May, 1850.

CONSIDERATIONS

ON THE

PHENOMENON

OF

REJUVENESCENCE IN NATURE,

ESPECIALLY IN

THE LIFE AND DEVELOPMENT OF PLANTS.

SCIENTIFIC investigation of the laws of Organic Nature
advances, in our times, in two distinct directions, one of
which may be called the physiological, the other the
morphological. Each, followed in a one-sided manner,
has led to multiplied contradiction in theory, which
can only be solved by a more profound biological method
of contemplation. Both directions hasten towards a pro-
founder comprehension of this kind; the former in a
negative manner, since, considering vital phenomena only
in their external physical conditions, it is led, at the
conclusion of every investigation, to a ground of the
phenomenon inexplicable on this side; the latter in the
positive way, since, regarding the forms, in connexion
with the history of development, as becoming, changing
and passing away, it must recognise a specific and indi-
vidual vital unity, running through all the changes of
form, unless the temporary products of development are
to dissolve away into inessential appearance, and to lose
all internal connexion. ‘The investigation of development,
in the smallest as in the largest circle, is, therefore, the

as 1

2 THE PHENOMENON OF

most profitable and most promising field of action in
natural history; and the remarks offered here belong
to this field, for they discuss a general question which
is not foreign to any special history of development.

Among the most essential and general characters of
every course of development of a natural object, are com-
mencement and term, and, connected with these, youth and
age. Youth and Age, although falling within the sphere
of ordinary human direct experience of life, do not appear
to me, in reality, so easily or simply comprehensible in
their true meaning and their contrasted relations, as
might seem from a mere abstract consideration. Answers
to the questions, so readily presenting themselves—How
are youth and age distinguished? When does youth
cease, and age begin? How do they pass into one
another? Which is the more perfect condition of life ?
—would penetrate deeply into the interconnection existing
among the totality of cosmical ideas. The purpose of the
present Essay only extends to a few reflections, based on
experience, on the changing relation of youth and age in
the course of the life-time of the individual.

Youth and age are not mere periods of time, into
which life may be divided so as to allow us to say,—Youth,
ceases here and Age begins; and one does not pass
gradually and continuously into the other, so that youth
decreases in the same ratio as age increases; a glance
into life rather demonstrates to us that the phenomena of
youth go through life side by side with those of age, in
the most varied conditions of exchange, not merely pre-
senting themselves simultaneously in various departments
of life, but crowding into the same region, and contending
there. Even the child has o/d teeth, destined to early
destruction (the milk-teeth), and young teeth (wisdom
teeth) appear even at a late age. Many organs have
already become old and lost their vitality before birth,
such as the gills of the Mammalia, the teeth of the
whale,* &c.; lizards and snakes form a young skin

* See Stannius, ‘Lehrb. der Vergleich. Anatomie,’ p. 411, on the teeth

REJUVENESCENCE IN NATURE. 3

annually, throwing off the old one; the crab changes even
his old stomach for a young one, every year. The
cotyledons, and even the radical leaves, as they are termed,
have already yielded to age in the (Zmothera, the rape,
and many other plants, at a time when the flowers still
remain in a young condition of buds, and, on the other
hand, the floral envelopes have perished when the fruit
is only in the commencement of its process of matura-
tion. In the pupa of the grasshopper, all the external
organs are fully developed, at a time when the wings are
just beginning to be formed. So may Man be a mere
child in mental development, when already old in bodily
respects. We see youth and age, therefore, presenting
themselves alternately in one and the same course of
development ; we see youth break forth in age, and enter
into the midst of the process, for the purpose of com-
pleting or metamorphosing the structures. This is the
phenomenon of Rejuvenescence (Verjüngung), which is
repeated in infinitely varied ways in all domains of life,
but nowhere asserted more distinctly and more accessibly
to investigation, than in the Vegetable kingdom. With-
out Rejuvenescence there can be no progressive develop-
ment; only the lifeless creation, or rather, that dying in
the moment of production, the mineral, is devoid of the
power of Rejuvenescence ; whence it is also deprived of
development and propagation.

Rejuvenescence appears, in the first place, as a return
to an earlier condition of life, whereby is obtained a point
of departure for renewed progress; or, in the extreme
case, as a retrogression to the commencement of the
entire course of development, to attain the aim in a repe-
tition of the development. The former we see in the
Rejuvenescences of the individual within the course of its
individual development, the latter in the Rejuvenescence
of the species through the succession of individuals. ‘he
retrogression just mentioned, introducing the Rejuve-

in the foetus of the whale. According to Eschericht the fetus of Balenop-
tera longimana has 102 teeth in the upper, and 84 in the lower jaw.

A THE PHENOMENON OF

nescence, is either morphological, the structure returning
actually from a higher stage into a lower formation ; as
we see, for example, in annual Rejuvenescence of many
herbaceous perennials (plante redivive), as also in most
woody plants, in the buds, which commence the rejuve-
nised course of life with leaves of the lowest stage of
formation, the bud-scales belonging to the “cataphyllary”
(nieder-blatt) formation ;* or the retrogression is merely
physiological, a chemical decomposition and dissolution
m the structure already existent, whereby this becomes
capable of a Rejuvenescence of its form, combined with a
more or less distinct metamorphosis. Such it is in the
interchange of materials in animals, with which are con-
nected their more gradual and imperceptible, as well as
the more sudden and surprising transformations. That
the like is not wanting in plants, will be demonstrated
in the succeeding examination of the phenomena of
Rejuvenescence in Cell-life.

We have consequently to distinguish a descending and
an ascending direction in the Rejuvenescence, one retro-
gressive, the other advancing with new impetus, one
undoing the old and existent, the other shaping out the
new. Both directions are necessarily related to that
renewal of the vital movement to which we have applied
the term “ Rejuvenescence,” and it is their alternation
which maintains life in vibration and guards it against
untimely rest. The smaller the vibrations in which it
occurs, the more constant will the formative process
appear to be, as for example in the processes completing
the structure of a cell not destined to division; but even

* There arises great difficulty in rendering these terms applied to the
different orders of leaves, since we have none corresponding to them in
English. They are so frequently used, not only in a substantive but an
adjective way, both in this treatise and in other recent German works, and
have such a definite meaning, that we venture to invent new words and to
use them in this translation. The word “ zieder-blatt,” (lower leaf), signifying
cotyledons, the bud-scales at the base of branches, or the scales of rhizomes,
is rendered by cataphyll; “ laub-blatt,” (\eafy-leaf), stem leaves generally, by

euphyll; “ hoch-blatt,” (high leaf), leaves belonging to the inflorescence, by
Aysophyll—A. H.

REJUVENESCENCE IN NATURE. 5

here the lamellar deposition of the coat of the cell betrays
the internal vibration of the formative activity. On the
other hand, the phenomena of Rejuvenescence appear so
much the more striking and surprising, the deeper the
depression of life preceding the new upraising ; and the
more distinct, consequently, the separation of the new
lease of life from the old, the more perfect the con-
sumption and breaking through of the old structure by
the new. The metamorphoses of insects furnish most
beautiful examples.

Inquiring into the causes of the phenomena of
Rejuvenescence, we recognise that external Nature, amid
which special life displays itself, acts in calling and awaken-
ing through the influences which the seasons of the
year, nay even the hours of the day, bring forth; but the
proper internal cause can only be found in the tendency
towards completion, which is present in every existence
according to its kind, and drives it to subordinate to itself
ever more completely the foreign and external world, to
shape itself within it, as independently as the specific
Nature allows. At the same time, however, a term
is set to the task, beyond which the phenomena of Re-
juvenescence do not proceed. As in mental life there is
a time of maturity, when youth and age are as it were
intermingled, when the restless strife of acquisition and
destruction ceases, when motion is paired with rest, so
also in the physical and corporeal there is an analogous
condition of maturity and relative rest, when the alterna-
tion of destruction and reformation is only carried on
in the small vibrations of the interchange of material,
maintaining vital motion and guarding against its being
benumbed. In animals we see this condition com-
mence when the organism has attained completion, is
“grown-up” as it is called, when nothing more new is
formed, but the actually existent enters upon its predes-
tined function, into its service in the more elevated side of
animal life. In Vegetable life we see the corresponding
phenomenon in thefruit, which Aristotle alreadyregarded as

6 THE PHENOMENON OF

the aim of the formative activity ofthe Plant. With it ıs
closed the series of structures, in the graduated production
of which the plant runs through its metamorphoses ; in it
vegetable life comes to a peaceful conclusion, yet without
the internal vital movement stopping at the same time with
the cessation of external growth, for it is not so inde-
pendent and permanent in any other part of the plant as
in the ripening fruit. At this stage of development,
therefore, in comparison with the preceding process, rest
comes at the end, but at the same time, according to the
relation to a higher sphere of life, the activity lying in
the destination of the final form.

If we compare the structures of the earlier stages of life
with the condition of the final forms, we see that in them
also exists a pause, an effort at conclusion, which, however,
has to be renounced before the development can advance
towards its term. In opposition to such fixation at
subordinate stages, which would become arrests of
development, comes the active power of Rejuvenescence,
spinning onward the threads of development with new
lengths. Thus it is in every single creature which has a
development at all, that is in every living thing. But
we may give this reflection a wider expansion.

The term reached by the individual, is not the last term
of development for the greater complex of the whole, nay
the individual itself indicates this totality in its depen-
dance. The individual existences of Nature are links
in the development of that Kingdom of Nature to which
they belong, and in the widest sense, links in the develop-
ment of the totality of natural life. Hence the phenomena
of Rejuvenescence present themselves not only in the
individual existence, but connect themselves again on all
hands with the term of the individual existence, going
beyond this, constantly renewing living Nature in her
individual members, and thus bearing up and carrying
her onwards to her final purpose. To the fruit adjoins
itself the seed as the commencement of a new individual
course of development, just as the production of future

REJUVENESCENCE IN NATURE. 7

generations is connected with the maturation of the
animal organism.

Against this general relation, however, of the phe-
nomena of Rejuvenescence to progressive development,
may be raised the objection that the cases of Rejuvenes-
cence last mentioned, on which depend propagation of
natural bodies, are, in point of fact, very different in this
respect from those first spoken of, those occurring within
the cycle of the individual development; in the one case
the aim of the Rejuvenescence would be a progress in the
development, while in the other it would be a mere repe-
tition of the like, as is distinctly demonstrated by the invari-
ability of species in the Animal and Vegetable kingdoms.
Yet this distinction vanishes when we test the gradations
of the cases, on both sides, and particularly if we rise above
the narrow field of vision of the present, in our examina-
tion of reproduction. The appearance of like alone being
repeated in nature, is removed in looking back from our
present stationary time into former epochs of the world.
There we find really the first beginnings of the species,
the genera, nay even of the orders and classes of the Vege-
table and Animal kingdoms ; we see at a glance how more
or less profound transformations were connected with the
appearance of the higher stages of the Organic Kingdoms,
so that genera and species of the ancient world disappeared
again, while new ones took their places. But through all
this change are expressed not mere accidental revolutions
of the earth, on the one hand of destroying, on the other
laying the basis of new soil for the flourishing progress
of organic life,—but far rather definite laws, penetrating
into the very details of the development of organic life.
Thus, for example, among the Vertebrate series the Fishes
appear first, then the Amphibia, and, subsequent to both,
Birds and Mammalia. The Fishes of the first periods, as
fish the lowest of their class,* resemble in many respects
the Amphibia, more indeed than the fish subsequently
appearing, of higher orders, from the very circumstance

* Agassiz. Poissons fossiles, Introduction, xxx.

8 THE PHENOMENON OF

that the types of the individual classes were less distinct
in the first representatives ; the special character of the
class, which is ever more distinctly impressed in the suc-
ceeding series of Fishes, not yet being fully developed.
Equally remarkable is the relation of the first Mammals
of the earth, the celebrated Marsupialia of Stonesfield,*
to the class Mammalia generally. ‘(he Marsupialia (in-
cluding the Monotremata) stand, as is well known, below
all Mammalia, nearest to the oviparous animals of the pre-
ceding classes, the Birds and Fishes, and not merely in
regard to the structure of the organs of generation. but
also in that of the brain; while, on the other hand, they
adjoin in their external form, in the structure of the
extremities and the teeth, the higher orders either of the
Herbivorous or the Carnivorous series, the Rodentia and
the Fere. We thus see again here the character of the
class imperfectly represented in the beginning, and the
subsequently diverging series of the class united even
to indistinctness. In the geological occurrence of the
separate sections of the Invertebrate animals, also, we
find the developmental connexion many times confirmed,
in that a determinate fundamental type appears first in a
few simple forms, then in the course of epochs the
number and multiformity of the representatives increase
more and more, till finally, when the series of forms is
developed to its extreme term, it often suddenly vanishes
again from nature, or leaves but a few representatives
behind. One of the most remarkable examples of this
kind is presented by the family of the Ammonites.

* Phascolotherium Bucklandi, and Thylacotherium Prevostii, Owen. Vide
Buckland, ‘Mineralogy and Geology,’ i, 72.

+ The transition period possesses the single genus of the family of
Ammonites, the Goniatites, the trias period the genus Ceratites, the Jurassic
age 11 sections of the genus Ammonites, the chalk period 14 sections of the
same genus, 10 of which are peculiar, and besides these the genera Crioceras,
Ancyloceras, Scaphites, Hamites, Ptychoceras, Baculites, Turrilites, and
Helieoceras, all of which occur exclusively in the chalk formation, with the
exception of Ancyloceras, of which genus the Jura formation already possessed
species. Then the family of the Ammonites vanishes totally. See Leopold
von Buch on „Immonites, and D'Orbigny, ‘ Paleontologie Francaise,’ 1, 433.

REJUVENESCENCE IN NATURE. 9

The Vegetable kingdom of the ancient world likewise
exhibits a periodical progress corresponding to a gradation
of structure still existing, since the oldest periods have
exhibited scarcely anything but Flowerless plants (Crypto-
gamia), which are soon followed by the Gymnosperms
(Cycadaceze and Coniferee), and in some degree by still
doubtful Monocotyledons, while the Dicotyledonous plants
appear distinctly latest. The results of geological re-
search appear to confirm, more and more, that all this
progress of organic nature, from the first onset to our
own time, has an essential connexion, and, although dis-
turbed in many ways by the catastrophes which the
earth has suffered, has never been altogether interrupted ;
in a word, that it represents a single history of develop-
ment, and not a series of separate and independent
creations.

The ancient changes in the living garment of the earth,
appear then as Rejuvenescences of organic nature in mass,
and the individual genera and species of the organic
kingdoms as subordinate links in its great chain of
development. ‘The fact that nature halted at determinate
points, in the calm intervals, and during the epochs pro-
duced, essentially at least, only the like, does not remove
the relation to the totality of the development. This is
the same phenomenon, on a grand scale, as when we see
the plant repeat itself in the same form, often hundreds
of times, at particular stages of its growth, before the
metamorphosis advances to a new stage, as for example,
often hundreds, or even thousands, of the ordinary
(euphyllary) leaves (Lirica, Calluna, Tamarix Abies), bracts
(hypsophyllary leaves) (Dipsacus, Cnicus, Celosia), petals
(Nymphea, Mesembryanthemum, Illicium), stamens (Pa-
paver, Dillenia, Helleborus), or carpels (Myosurus,
Anemone, Anona), are formed in unbroken succession on
one and the same axis. But even in these times of
halting, by no means the absolutely like is formed. No
leaf, even when belonging to the same formation, exactly
resembles another; and with every successive leaf, if the

10 THE PHENOMENON OF

development advances as far as the terminal blossom, the
plant approaches one step nearer the formation of the
flower. Neither are the individuals of the same species
exactly alike; and the capability of developing certain
sets of varieties testifies the developmental power of the
species, even within the restriction to the specific type.
We cannot, therefore, ignore a certain relation to the
development of the great whole, even in those phenomena
of Rejuvenescence which continue the series of individuals
in what seems a mere repetition of the like. ‘This rela-
tion speaks most meaningly in the highest region of the
whole graduated series of Nature, where the development
passes over from the physical into the spiritual. Who
would deny the relation of the production of new genera-
tions to progressive development, in the field where it
lies nearest to us, namely, in the Human Race? The
condition of humanity in this respect falls within the
sphere of our contemplation, for the aim to which the
infinite Rejuvenescences throughout all Nature strive,
through the attainment of which our period of creation
is distinguished from all the ancient epochs, is the very
existence of Man, towards whom Nature points, from step
to step, ever more distinctly throughout her entire series ;
and Man again cannot be considered without that which
itself constitutes his humanity, the development of Mind.
The development of Mind cannot be separated from its
substratum Nature, since although Mind itself is destined
to rise victorious over all the obstructions of physical life,
it must also penetrate backwards through all the stages
of that life, and give them a spiritual signification.
Only by starting from this standing point, fixing the
aim of the entire development in Nature, can we find the
true internal connection of all the gradations of natural
life, and by the very conjunction with the course of
development of Man, Natural History acquires its highest
import. As Nature without Man presents externally
only the image of labyrinth without a clue, scientific
examination which denies the internal spiritual founda-

REJUVENESCENCE IN NATURE. li

tion of Nature, and its essential connection with
Mind, leads only to a chaos of unknown matters and
forces,* that is of matters and forces which are sealed
books to the mind, or more properly of unknown causes
which co-operate in a manner to us inexplicable. From
this dark chaos no bright path leads up to the mind;
nay, it is inconsequent to regard the mind from this
point of view as anything but an inessential result of the
co-operation of unknown causes. The study of develop-
ment is pre-eminently calculated to defend us from such
a miserable spoliation of Science, for the connection of
the perceived phenomena of Being must necessarily lead
us to the recognition of the Becoming, as an internal
essence (specifically) the same through all changes.

The comprehension of the individual phenomenon as a
member of a series of essential correlative representations,
requires not merely the carrying back of the research to
the earliest rudiment, from which alone the succeeding
transformations can obtain their correct interpretation,
but also a continuation of the observation up to the term
of the development, whereby is first perceived, on the
other hand, the true destination of the efforts in the
formative processes. This is equally true of individual
organs, whose physiological destination is first distinctly
realised when the formation is complete, and of the indi-
vidual whole, whose specific and generic character is
chiefly expressed in the last stage of the metamorphosis,
—for example, in the flower and fruit of the Plant. This
is true, moreover, of the more comprehensive develop-
mental series in Nature. ‘The character of every genus,
family, class, &c., should grasp its type, as it were its
idea] object, for which purpose the lower members of the

* The sadness of such an essence-less view of nature, which of course must
strive to eradicate fromthe ideas and language of science, all which from its
own standing point appears anthropomorphic, does not strike us in its
fulness, simply from the fact that the desired eradication cannot be so readily
carried out, on account of the intimate and immemorial blending of the
more profound ideas with human language. See Schleiden, ‘Die Pflanze
und ihr Leben,’ 15. ‘The Plant,’ translated by A. Henfrey.

12 THE PHENOMENON OF

series are always less fit than the higher, in which it ıs
stamped more plainly and completely. Thus in the
Ornithorynchus the type of the Mammal is so imperfectly
and aberrantly represented, that doubt could long exist
whether it belonged to the series of the Mammalia at all,
and the flowers of the Cycadez are so little like a flower,
that it was only after much comparative study that the
conviction was arrived at, that these plants actually belong
to the commencement of the series of Flowering plants
(Phanerogamia). If we apply this mode of examination
to Nature as a whole, as the developmental series in-
volving all the subordinate series, if we here also seek the
solution of the problem, at the term of the development,
we are most distinctly directed to the completion of the
development of Mind as the destination of the whole pro-
cess, becoming visible at the highest stage of natural life.
The mind which becomes developed in Man, is not fitted
together, with the physical organism, from without, for we
behold its evolution indicated in the lower stages of
natural life, especially in the Animal kingdom; the
spiritual life is rather the purest and most refined repre-
sentative of the fundamental life, which we meet as
natural life in the preceding stages. We may say of
Mind, that it is the youngest, and yet the oldest, existence
in nature, destined to attain in its last age, its eternal
youth, the freedom fitted to its essential nature. Rising
from the groundwork of Nature bearing and supporting
them, the spiritual Rejuvenescences in the history of Man
strive towards this aim of internal vital emancipation,
driving the mind out of every senility, every fetter of
time, to soar upward in a new flight of life.

‘Thus is our own history connected with the history
of Nature. ‘The thought of Rejuvenescence in Science,
Church and State, now again moves nations, and
meets us in the most varied efforts, in ways crossing one
another in manifold directions. As yet, alas, we have
become acquainted almost solely with the negative side
of these efforts, the Destructive ; but in the eyes of the

RUJUVENESCENCE IN NATURE. 13

naturalist this dissolution would tend merely to indicate
the proximity of the transition to a new, upgrowing time
which will seize the Positive, in all fields, more pro-
foundly, and give it a more perfect shape. Will this
hope be fulfilled? Has not Old Europe rather arrived
at a hoary age, and an approach to its dissolution?
The answer to this must be written first of all in our
own hearts; but if you would seek it externally, look
with the eye of the naturalist into the hidden workshops
of the future, and you willfind an infinite abundance of
germs and buds, which bear the promise of a rich future
within them ; you will above all find them in the domain
of Science, as the highest region of mental development,
from which alone the latest reformations of life can and
ought to issue. But these are digressions leading us too
widely from the purpose of the foregoing considerations.
If however it be true that all the domains of life are parts
of a great total development ; if it be true that every de-
partment of science leads in its more profound establish-
ment to the same eternal idea, which is the foundation of
all reality and all truth,—each department must be
mirrored in the others, and thus the naturalist may be
permitted to contemplate each movement of the human
life which surrounds him, in the mirror of Nature; to
find in whose lawfully connected government, the key to
calm judgment, is often his gain and payment.

In the preceding observations we have sought to regard
the phenomenon of Rejuvenescence in its general, exter-
nal mode of appearance, and to mark out the wide field
in which it is repeated in such a multifold and yet es-
sentially always the same way. A profound investigation
into the nature of Rejuvenescence would pre-require
somewhat minute research into the essence of age and
youth. A few more remarks upon youth may be per-
mitted here. According as we regard life as a mere
result of external causes, or discover its basis in one
original internal endowment, will youth appear to us, in
the one case as poverty, want, and crudity, in the other

14 THE PHENOMENON OF

as the yet undivided fulness and strength of the unde-
veloped existence, as superabundant wealth of energy,
striving to unfold itself. These two modes of considering
the question occur, for example, in application to the
earliest, youthful stages of the Human Race ; thus we find
on the one side the doctrine of the originally animal con-
dition of Man, according to which Man, scarcely distin-
guishable from apes, probably of black colour, perhaps
even sought after his nourishment on all fours or climbing,
devoid of art, language and thought ; then gradually dis-
covered speech through imitation of natural sounds, and
as it were accidentally; and was only led through external
necessity, not through internal impetus, through the com-
bat with external nature which his extraordinary defence-
lessness and helplessness brought upon him, to each
flight upward of life in art and civilization, upbuilding
all progress from without, not unfolding from within.
In opposition to this representation stands the doctrine
of the paradisaical condition of the first Man, who at his
first appearance stood face to face with obedient Nature,
as Lord, as complete Man and likeness of God, urged by
the fulness within to give outward shape in word and
work to his inborn divine ideas. When we acknowledge
both the internal and external, in their co-operation in
life, we shall easily be able to unite these two views, that
is if we disregard the exaggerations on the one side, and on
the other the mythical imagery (which represents the inner
potentiality as the external actuality.) The insufficiency
of the first view, which logically carried out entirely dis-
owns anything internal and essential in natural phe-
nomena, may be shown us, if, as was referred to above,
we do not find it in our own life, or are disinclined to
draw conclusions from that as to life outside us, by the
instinct of animals, in which is revealed so great an
abundance of gifts, not given from without, but un-
doubtedly inborn, as the gift of song, the impulses to art,
or to migration, &c. The phenomena of mental life in
animals, which we ascribe to Instinct, have been correctly

REJUVENESCENCE IN NATURE. 15

compared with what has been called, in the material
sphere, the specific formative impulse, or typical force.
Instinct is the continuation of the formative impulse in
a higher sphere, as is particularly clearly manifest in the
phenomena of the constructive impulse, in the formation of
envelopes and clothing (Serpula, Phyganea, Psyche), nests
and dwellings, as a kind of ulterior and more external
material organisation. The specific formative impulse,
however, is not an outwardly derived direction of the
activity, but one inwardly contained, acting, from internal
causes, as inner determination and force. This is shown
by the fact, that under like external conditions of exist-
ence, the organism shapes itself in a peculiar, specific,
nay even individual way, in each creature, whence the
multiformity of the picture which every mingled wood,
every meadow, every field, displays to us. Hence in the
grove we see the woodruff and the herb Paris, later in the
summer the willow-herb and the fox-glove, on the rock
the oak-fern, the dragon’s-mouth, and the stone-crop,
side by side; they take up the same nourishment, and
form their structures out of the same elements. What
maintains them in the distinctness? It is the same force
that enables different animals to elaborate the same food
for such constantly varying bodily development, and, on
the other hand, prevents a considerable change of food
from effacing the specific type. This internally given
force of life is pre-eminently expressed in youth, while in
later age the formative forces are more and more fettered
to the products of their own activity, and work only in
a narrower circle, till at length their activity, every-
where more hampered in its own products, becomes
extinguished.

For the definition of Rejuvenescence, we draw from
the foregoing considerations, the conclusion, that the
renouncement of forms already attained, and the retro-
gression to new rudiments, with which Rejuvenescence
begins, only mark the external side of the process, while
its inner and essential side is rather an inward gathering-

16 THE PHENOMENON OF

up, as it were a new draught from the proper source of
life, a renewed recollection of the specific purpose, or a
renovation of the conception of the typical ideal, which is
to be represented in the outward organism. ‘This gives
to Rejuvenescence its definite relation to development,
which can only bring into gradually perfected repre-
sentation, that which lies in the essence of the creature,
that which is inwardly its own.

This inner part of the process of Rejuvenescence may
be rendered more clearly comprehensible by sleep, for
this also is a phenomenon of periodical Rejuvenescence,
the Rejuvenescence of the consciousness. In sleep the
mind is relaxed from the tension in which it is held
towards the outward world while awake. All images
and shapes of thinking life vanish, or appear only as
reflected pictures in dreams; the mind sinks back into a
condition comparable to that in which it was before it
first awoke to consciousness, therefore, externally regarded,
to a lower condition of development, for sleep is older
than waking in the history of development of human life.
But the mind does not lose itself in sleep, it rather
gathers itself up into new force, new comprehension of
its purpose, and much that crossed the waking thoughts,
scattered and entangled, becomes sifted and arranged
through this recollection.

Sleep, a necessary recreation for the mind, is equally
required by all the powers of the body immediately
serving the mind. The inner formative processes, on the
contrary, through which the body itself is preserved, do
not rest during this time of retreat, they rather act the
more undisturbedly and concentratedly. Hence the
rejuvenising power of sleep also for the body, which
appears so wonderful to us in many cases, as when sleep
occurs at the crisis in severe diseases. But the most
remarkable instance of the connexion of sleep with bodily
Rejuvenescence, is seen in the pupa-sleep of insects. Here,
where occur the most important metamorphoses we know
in the Animal kingdom, that of the sluggish caterpillar

REJUVENESCENCE IN NATURE. 17

into the light-winged butterfly, the footless or headless
maggot into the deeply-segmented fly ;—here, also,
occurs the greatest retreat and gathering i in of life, a
deeper sleep of weeks, months, or even years’ duration,
which may be compared with the embryonal sleep in the
earliest period of formation of the organism, the sleep in
the egg. Without nourishment and without locomotion,
as it were shrouded in its pupa-coats, the insect prepares
the rejuvenised body for its future resurrection into a
freer, more mobile existence.

The awakening of the butterfly from the pupa-sleep,
recalls to us the awakening of Nature from its winter sleep
in Spring; and this leads us to the proper subject of the
present considerations,— the Rejuvenescence in Vegetable
life. The Vegetable Kingdom is, indeed, the principal
workshop of Spring: “ the” wonderful workshop where
myriads of vegetable atoms, in brief space, spin the
threads to clothe the trees and weave the verdant carpet
of the earth. With all its sunshine over land and sea,
with all its swelling streams and brooks, Spring would be
barren and empty without leaves and flowers, as a sky
without stars. Leaf and blossom alone give life and fresh-
ness to the active scene.’ *

First of all, however, we must here dispel the illusion
that all the splendour of the new-born vegetable world,
which appears so magically in spring, is merely the work
of the few days in which it comes so suddenly into view.
No, the labour of Rejuvenescence begins earlier in the work-
shops of vegetable life, and Spring merely brings the last
steps before our eyes. ‘The breath of Spring only urges
to its unfolding that which was prepared long before in
silence, that which was reserving and strengthening itself
during the evil season of winter. For in the same pro-
portion as the vegetable world advances in summer and
autumn,—in shoot, leaf and flower, in wood and fruit, in
obedience to the impulse to outward representation, to

* Blias Fries, “der Fruhling’ (Spring). ‘Archiv Scandinav. Beitrag,’ i
pp. 182, 214.

?

2

18 TUE PHENOMENON OF

expansion and firmer establishment, does it retreat simul-
taneously into itself in the formation of buds and seed, to
prepare the germs of new life. Thus the greater part of
that which unfolds itself in Spring, after winter has passed
over it, was already formed in the preceding summer and
autumn. Even now in August we find in the terminal
and lateral buds of the oak, within numerous, five-ranked
bud-scales, the rudiments of the leaves destined for
next year; nay, in the mostly paired terminal buds of
the dilac (Syringa), we find not only these, but the rich
thyrse of blossom for the future year, with hundreds of
closely crowded flowers, which at this time indeed appear
only as inconspicuous green nodules, scarcely the twelfth
part of a line in diameter. In the heart of the Zulip
bulb, shielded by three- to four-fold succulent leaf-scales
(cataphyllous coats, Miederblatt-hülle), exists, in autumn,
a little greenish-yellow bud ; thisis the tulip stem for the
next year, with all the parts which it elevates from the
earth nine months later, namely, two or three leaves,
between which les hidden the blossom, scarcely a third
of a line high, the petals and stamens appearing as ex-
tremely sinall, uniform papilla, scarcely distinguishable,
and not yet closed in as in later shape of the flower-bud,
while the pistil is visible in the middle as a little, three-
lobed papilla. The spike of the Ayacynth is somewhat
more advanced, at the same period, in the interior of the
many-scaled bulb, for the three outer petals of each flower
already begin to close up. In Ophioglossu, a strange
little plant of the alhance of the Ferns, which unfolds
annually only one leaf and one spike, we find in May, in the
bud still hidden under ground, enclosed in a cellular cover-
ing, (not formed of cataphyllary leaves or bud-scales, but
thallus-like,) not only the leaf and spike for the next
year, but also the rudiment of the leaf for the year after that.

A further penetration into hidden workshops of Reju-
venescence i plants, requires, first of all, a more minute
investigation of the bud. The plant is bud, so long as
its existing rudiments are kept, in relation to completion,

REJUVENESCENCE IN NATURE. 19

in a stage of close connection of the organs. ‘Those things
which are subsequently removed and unfolded, are here
still closely approximated, and, as it were, fitted one
within another. The bud is, therefore, properly regarded
as an entire young plant, and each new bud on an old
stem as a new plant, as an individual : “Gemme totidem
herb@”’ was an axiom laid down even by Linnzeus, and
since his day has oftentimes been repeated.* Neverthe-
less, this conception of the bud has remained itself to a
certain extent in the condition of a bud, since the sur-
prising abundance of conclusions derivable from it, have
never been properly developed up to the present time.
In the first place, however, the idea of the bud as indi-
vidual still requires an essential clearing up. Since the
word dud merely expresses a certain stage of existence of
the thing in question, we must here rather call this sprout
(Spross), in the definite sense that we here understand
by sprout all belonging to one axis of the plant, that we
therefore regard as belonging to a sprout all which is
produced directly from one centre of vegetation (punctum
vegetationis), and belongs essentially to one line of deve-
lopment. Hye and dud are only the commencement and
young condition of the sprout; and that which we call
bud frequently comprehends only one part, and not the
whole of the sprout, as when the lower portion of a sprout
is already unfolded and the upper part of it alone remains
in the condition of a bud. ‘Thus every richly clothed,
but gradually progressing and gradually unfolding leaf-
bearing axis, as, for example, the sucker of the willow,
the rosette of the lettuce before its flower-stalk has arisen,
the crown of the palm or of the agave, has a bud (a
“heart’’) hidden among the uppermost leaves, which
bud, however, passes by almost imperceptible gradations
into the unfolded part of the crown, rosette, or shoot.
In other cases there is a sharper division between the
earlier unfolded parts and those remaining long in the

* For instance, by Roper, (‘ Linnea,’ 1826, p. 434,) and quite recently by
J.N. Carus, (‘Zur näheren Kenniniss des Generationswechsels, 30.)

20 THE PHENOMENON OF

bud state, in reference to the period of unfolding and the
stage of formation; thus, for instance, in the oak, the beech,
and other trees, where the leafy shoot terminates in a bud,
the shoot does indeed begin again with cataphyllary leaves
(bud-scales), and unfolds itself a year later than the pre-
ceding portion of the branch, but is, nevertheless, the
direct continuation of the axis, and therefore belongs to
the same sprout. So also when a flower-bud forms the
termination of a sprout, on which the preceding forma-
tions were unfolded earlier than the terminal flower, as in
the tulip, the ranunculus and the peeony. Hence it is not
the separated bud which we must regard as dn individual,
but the entire shoot, which in these cases includes several
superimposed buddings. A Rejuvenescence in the
course of formation of the plant, is indeed expressed in
each production of a bud; but we must not, therefore,
attribute an equal individual importance to each, for some
buddings belong to the individual completion of the par-
ticular branch (all terminal buds), while others form the
commencement of the new individual line of development
of a new sprout, as is the case in all lateral buds. If
individual value be attributed to the terminal buds also,
it will follow, in reference to the cases where the terminal
bud unfolds gradually, and is renewed in like progression
in the centre, that we must accord the rank of an indi-
vidual at last to every single leaf with its supporting
internode, since each is a specially rejuvenised link of the
progressive development. And if we attribute an equal
importance in this respect to each step of Rejuvenescence,
we cannot stop here, for then every organ of the plant,
as internode and leaf, is itself again formed by a series of
Rejuvenescences, as we see in the cell-formation of the
organs; and the single cell itself finally has its own
periods of Rejuvenescence. Consequently, if we wish to
review the various gradations of the phenomena of Reju-
venescence in vegetable life, we must consider separately:
—1, the Formation of Sprouts; 2, the Formation of
Leaves; and, 3, the Formation of Cells.

REJUVENESCENCE IN NATURE. 2]

1.—IHE FORMATION OF SPROUTS.

There cannot be any doubt that the formation of
sprouts belongs to the class of the phenomena of Reju-
venescence, for with every sprout commences a new
train of development, the relation of which to the entire
developmental chain of the specific vegetable life, we have
here especially to investigate. The principal sprout of
the plant takes its origin from the seed, and is indeed
merely the direct development of the seedling (embryo),
thus grown up from the first pomt of vegetation of the
plant, which, traced backwards, leads to the primary
germinal vesicle. The lateral sprouts (branches), al-
though their origin is unconnected with the co-operation
of the sexes, agree with the main sprout in that they
also are developed from special centres of formation,
distinct, after their first origin, from the principal sprout.
We shall return in the sequel to the origin of the principal
sprout, with which every new vegetable “ stock’’* arises,
when examining propagation from the point of view of
cell-formation ; here we must occupy ourselves with the
lateral sprouts, which belong to the sphere of com-
pletion (Ausbildung) of the vegetable “ stock” itself.

Unfortunately we are deficient in thoroughly worked-
out researches on the origin of the lateral sprouts or
branches; but so much is known, that the origin of the
sprouts is subsequent to that of the leaves, that they
derive their origin from the already more developed
tissues of the stem, while the first rudiment of the leaf
coincides with the earliest stage of formation of tissue
underneath the point of vegetation.t While the leaf,

* The word “stock” is used here and elsewhere in the sense of what may

be called a phytidom (like a polypidom), indicating the total organically
connected structure composed of a number of partially independent links
or members.—Zraas.

T Vide Nageli, ‘Zeitschrift fur Wissenschaftl. Botanik,’ Heft ui, iv,
pp. 158, 177.

22 THE PHENOMENON OF

as essential part of the sprout, has its history of develop-
ment intimately connected with that of the stem;* on
the other hand the formation of the sprout does not
seem to have any essential connection with the com-
pletion of the stem from which it proceeds. This is
further confirmed by the circumstance that the sprouts
are not always distributed, like the leaves, in definitely
regulated order on the stem, but in many cases may
arise without order at any points of herbaceous stems,f
or of the older lignified trunk, nay even from the root}
and the leaf, as the so-called adventitious buds.

It is a remarkable mdication for the essential dis-
tinction m the origin of the leaf and sprout. that no
adventitious leaves occur. ‘The character of the new
formation is expressed most distinctly in the formation of
adventitious buds making its appearance in detached
fragments of roots of woody plants, as has been described
by Trecul in Ailanthus, Paulownia, Tecoma, and Maclura.
Here, in a deep-seated layer of the cellular bark, a new
focus of development is formed through a local thicken-
ing of the cellular tissue, and on this point again origi-
nates a much more delicate mass of cellular tissue, a new
sphere of formation, which soon grows externally, al-
though still enclosed in the tissue of the bark, into a
leaf-producing point of vegetation, and on the inside
strikes, stem-like, into the formative zone (the cam-
bium-layer) of the root, there, by the formation of a
proper system of vessels, which takes its origin on the
limit between the stem of the adventitious bud and the
wood-cylinder of the root, acquiring a firm connection

* The essential interconnection of the leaf and stem is expressed in the
completed structure also, in the fact that there is no sharply defined limit
between the leaf and the portion of stem bearing it. Remark, for instance,
the pulvini gradually lost in the stem of Larix, Picea, Cactee, Cacalia
articulata, &c., and stems winged by the decurrence of the borders of leaves.

+ In Euphorbia, Linaria, and Anagallis, from the internode below the
cotyledons.

+ Frequently in woody, rarely in herbaceous plants, e. y. Huporbia Cypar-
issias, Linariv, Rumex acetosella, tjuyu genevensis, Nasturlinm pyrenaicum,
Jurinen Pollichii, and Helichrysum arenarium.

REJUVENESCENCE IN NATURE. 23

with the latter.* The bud breaks out subsequently
through the bark in which it was previously concealed.
In this instance there can be no doubt that the sprout is
really a new, and in this case even an accidental product,
a new commencement of life, which creates its own
sphere of formation, its own point of vegetation, and
through the development of this, its own axis, around
which it arranges its organs. Hereby we are warranted
in regarding the sprout as an individual, for, if we may
ascribe individuality to the plant generally, in which we
are certainly justified by the repetition of its mode of
appearance in determinate cycles of development, we
must, consequently, conceive the individual as a develop-
mental series of unit power, and set up as its criterion
the unity of the point of vegetation from which the series
proceeds, or, in the developed condition, the unity of the
axis. According to this, only the simple sprout can be
regarded as a vegetable individual, and that this, far
as the vegetable individual stands behind the animal
individual in inner unity, is actually the analogue of the
animal individual, is proved beyond all doubt by com-
parison with those animals in which “ family stocks’ are
produced by the formation of sprouts.

The formation of the compound vegetable “ stocks’
(trunks or common stems) is thus a phenomenon of pro-
pagation, if we use this expression according to the
meaning of the word and the custom of language, in
general application to the production of new individuals
for the increase and maintenance of the species of plant.
Propagation by the formation of sprouts, on which not
only depends the formation of compound stocks, but in
which is also given the possibility of the formation of
separate stocks, has indeed been distinguished as mere
multiplication from the proper (sexual) propagation, or

* Trécul ‘Recherches sur lOrigine des Bourgeons Adventifs.’ ‘Aun.
des Se. Nat.,’ 3 sér. vili, 268, 1847. The cases there described as two
different modes of origin, and represented i in Plate vu, fig. 6 under 4 and 4,
may probably be only stages of one and the same process.

24 THE PHENOMENON OF

called propagation of the individual, in contradistinetion
to the propagation of the species effected by the forma-
tion of seeds.* But, disregarding the contradictions
which here exist even in the expression, these definitions
by no means reach the true essence of the modes of
propagation occurring in the formation of sprouts, for it
is incorrect that the formation of the sprout is mere/y for
the object of multiplication, as I shall endeavour to show
in the sequel; in like manner it does not always apply,
that the new stocks formed by separation of sprouts
(cuttings, layers, &c.) constantly retain unaltered the indi-
vidual (more accurately the variety’s) character of the
parent stock, for even without separation from the stock,
particular shoots “ sport,” as it is called, out of the species.
The well-known example of the occurrence of isolated blue
bunches of grapes on stocks of white varieties, isolated
bunches of red currants mingled with the white ones of
the same stock, isolated pure sulphur-yellow roses among
variegated flowers of the red and yellow Austrian briar-
rose (Rosa eglanteria, var. bicolor) afford proofs of this.
‘The remarkable phenomena relating to this point in the
hybrid Cytisus Adami, which displays in particular
sprouts the characters sometimes of one, sometimes of
the other parent species, will have more particular atten-
tion paid to them in another place.

The true import of the formation of sprouts upon the
vegetable stock is that of a subordinate propagation.
The cycle of development given by the sexual propaga-
tion (formation of seed) divides again, in the majority of
plants, in the most varied manner, into subordinate
series of development, which proceed out of one another
by the formation of sprouts, so that what in more highly
individualised beings is completed in the simple indi-
vidual, is distributed in the plant, through the inter-

_* Link, ‘Element. Philos. Bot.,’ p. 208. “Gemme individuum con-
tinuant, cum semina speciem propagent.” We have already shown above

that the lateral sprout, morphologically considered, is no continuation, but a
new beginning.

REJUVENESCENCE IN NATURE. 25

position of a subordinate process of propagation, among
a society of individuals, a developmental series, and a
family circle formed thereby. The subordinate nature
of this mode of propagation represented by the formation
of sprouts is expressed—1. In the connection of the
formation of sprouts with the lower stages of develop-
ment of the plant. 2. In the imperfection of the
“sprout individual” in reference to the series of stages
of development which specifically belong to the plant.
3. In the complementary relations in which the various
sprouts of the same plant stand towards each other.

In the first respect, all sprouts agree, with the ex-
ception of the seed-sprouts (commonly called ovules),
which as standing in the closest relation to sexual propa-
gation, may be here left out of consideration. All other
sprouts spring from the so-called vegetative region, while
inside the flower, omitting monstrous occurrences in
antholyses, no more formation of sprouts takes place.
The cataphyllary (Meder-blatt) region, the euphyllary
(Laub) region, and the hypsophyllary (Hoeh-Dlatt) region,
have more abundant or more sparing formation of sprouts
according to the peculiarity of the species of plant; nay
the production of sprouts is not unknown, as already
mentioned, in the descending portion of the plant, the
root. How characteristic the formation of sprouts is of
the vegetable “stock” is shown by the circumstance that
there exists perhaps not one single plant wholly without
the formation of sprouts.* If this assertion look at first
strange, considering the number of plants which are
diagnosed with “ caule simplici” and “ simplicissimo,”
more accurate examination of such plants as appear
to want the formation of sprouts, will readily confirm it.
A few instances may serve to bear this out. Cicendia
‚iliformis is certainly one of the simplest plants in this
respect. A delicate threadlike stem bears a few pairs
of small euphyllary leaves and ends in a terminal blossom.

* The leafless plants of the lowest ranks of the vegetable kingdom are
temporarily passed over in this assertion.

26 THE PHENOMENON OF

But the rudiments of the formation of sprouts exist in
the axils of the lower leaves of this series, and quite as
many specimens may be found with one or two branches,
as perfectly simple. In a similar way, in many other
plants which usually possess abundant ramification, we
find specimens which, under the influence of unfavorable
conditions, do not complete the branches which really
exist in rudiment, and therefore appear quite simple.
Such simple “ arrests” (Kümmerlinge) occur, for example,
in Erythrea pulchella, Gentiana utriculosa, Saxifraga
tridactylites, Silene conica, Gypsophila muralis, Papaver
Rheas, Myosurus minimus, &c. In all these cases, there-
fore, the want of branches depends solely upon an acci-
dental obstruction. Other plants appear simple because
the formation of sprouts is hidden beneath, or is close
down upon the earth, as in the tulip, which forms sprouts
in the cataphyllary leaf region (bulbels), also Trollius
europeus, Papaver nudicaule, Gentiana verna, which
form sprouts in the axils of the ground leaves (“ radical”
leaves), whereby the originally simple “stock” passes
into a ceespitose complexity, and acquires what is called a
“radix multiceps.” Paris is deceptive in another way,
the simple and one-flowered erect stem being itself a
lateral sprout from a subterranean cataplıyllary-leaved
stem (rhizome). Among the simplest plants altogether
devoid of sprouts, apparently presenting solely a flower
without a stem, is the celebrated Raflesca and the para-
sites nearly allied to it; but it is most probable that the
flowers of these plants arise as sprouts out of a thallus-
like basis, creeping along under the bark of the nursing
plant.* ‘The Melocactee form an exception in the family
to which they belong, ungrateful to the admirers of that
family, in sending out no sprouts from their green,
globular “ stocks ;” but here also the rudiments of the
formation of sprouts are indicated, by headed-down
“stocks,” sometimes sending out sprouts from the lower

* Sce R. Brown ‘On the Female Flower and Fruit of Raffesia tracldi. &e.
“Trans. Linn. Soe.,’ xix, 3, p. 232 (note).

REJUVENESCENCE IN NATURE. 27

portion; moreover, Melocactus normally exhibits formation
of sprouts in the terminal tuft of flowers, in which (as in all
Cacteze) the flowers stand laterally. The palms are also
mentioned as plants which usually form no sprouts; but
leaving out Cucifera thebaica, which acquires a multiple
crown by the formation of leafy branches, the inflorescences
originating in the axils of the leaves are lateral sprouts.
Corypha umbraculifera, with terminal inflorescence, has,
in the inflorescence itself, ©. e. in the hypsophyllary leaf re-
gion, an extremely rich ramification, carried out to many
degrees, and in addition to this, sends out sprouts from the
root, at the time of the maturation of the fruit.* Cycas
would have better right than the palms to be regarded as
a plant devoid of sprouts, at all events if the cone-
or Ananas-like male blossom is terminal, as Richard
expressly states. But Rumph says of Cycas circinalis,
that the stem at first grows very slowly, but afterwards
more rapidly, particularly when it has borne the “ananas.”’
Such a continuation of the growth of the stem can, how-
ever, only be conceived through the formation of a lateral
sprout, if the male blossom is actually terminal, or, if a
direct prolongation of the stem occurs, the male blossom
must be a lateral sprout. The female tree of Cycas
circinalis is stated by Rheede + to divide frequently into
four or five tops when old, which again can only take
place. by the formation of sprouts. Lastly, in Cycas
revoluta, formation of sprouts from the lower part of
oldish stems, mostly close down to the ground, is quite a
common phenomenon, and may be seen in every old
trunk in our gardens; recurring moreover in the fossil
stems of Cycadee.} Many Ferns, especially most tree-
ferns, would appear as sproutless plants, in the strictest
sense of the word, were not the entire Fern stem itself a

* Vide Mohl, in Martius’s ‘History of the Palms.’ The palms are also
very subject to subterraneous branching, and lateral sprouts sometimes break
out from old leaf-axils on full-grown trunks.—A. H.

t Hist. Malabar., iii, t. 20, fie. 3.

% See plates in Buckland’s ‘ Geology and Mineralogy, t. 55, 60, 61.

28 THE PHENOMENON OF

second generation, ö.e. a sprout produced from the
thallus-like pro-embryo (prothallium). 'The circumstances
are similar in Jsoétes. Thus, even after very extensive
investigation, there probably does not remain to us one
single plant which, through the whole course of its deve-
lopment, from the germinal vesicle to the fruit, is but a
single, simple individual, uncomplicated by subordinate
propagation.*

The subordinate condition of the propagation pre-
senting itself under the form of the production of sprouts
is expressed, secondly, in the fact that the particular
sprouts, and indeed the main sprout as well as the lateral
sprouts, do not, in the majority of cases, bring into exist-
ence all the stages of vegetable metamorphosis which
belong to the “stock” as a whole. Consequently there
exist, in reference to the share in the graduated structure
of the entire plant, sprouts of different kinds, and the
individual sprout on that account mostly represents only
more or less imperfectly the history of life of the plant.

The deficiency of the sprout may relate either to its
commencement or its conclusion. The formation with
which a sprout commences mostly stands in relation to
the region of the parent-shoot from which it takes origin.
Thus we frequently see a series of sprouts, accurately
graduated in this respect, arise from successive regions of
the (absolute or relative) main-sprouts, e.g. sprouts
beginning with cataphyllary structures from the cataphyl-
lary region, with euphyllary leaves from the euphyllary
region, with hypsophyllary structures from the hypsophyl-
lary region. Hypericum perforatum and Mentha aquatica
are well-known examples exhibiting this phenomenon.
But a retrogression of the sprout to a lower formation, as
well as an advance to a higher, is possible. The former

* See on this subject, Hofmeister, ‘ Frucht-bilding, &e. der höher. Krypto-
gamen,” Leipsic, 1851. He however regards the fronds of ferns as branches,
a view which does not appear admissible. The first product from the pro-
thallum is the primary axis of a new individual, continued by a terminal
growth, but forking of the rhizome may oceur, and this must depend on the
formation of secondary sprorts. In /soeles the stem appears simple.—A. H.

REJUVENESCENCE IN NATURE. 29

occurs especially when the sprout is destined to be sub-
sequently developed into the central shoot. Thus many
hlies exhibit in the axils of the euphyllary leaves cata-
phyllary buds, which finally fall off as bulbels, and con-
tinue their development in the following year ; so also
we see the buds formed in the axils of the euphyllary
leaves of most trees, intended to overlast the winter and
unfold in the next year, commence with cataphyllary
structures. In many instances the plant first reaches the
lowest stage of its metamorphoses by such a retrogression,
the lateral sprout going down to a lower rudiment than
the main or original sprout brought forth by the seed.
This is a process through which the plant enters more
closely into connexion with the earth in the second
generation than in the first, and becomes more firmly
established in it, preparing a more fixed, enduring and
sheltered existence, to the vegetable life, though its cata-
phyllary formation and the adventitious roots mostly fol-
lowing this. ‘The followmg remarks may serve to illus-
trate this case, which is especially important in reference
to the biology of perennial herbaceous plants. It is self-
evident that the cotyledons of Dicotyledonous plants,
although mostly strikingly different * in shape from all
the following leaves, do not belong to the lowest leaf-
formation, but rather bear, essentially, the characters of
the second leaf-formation, that of the euphyllary leaves ;
while, on the other hand, the sheath-like cotyledon of the
Monocotyledons is mostly decidedly like a cataphyllary
leaf. Now Dicotyledons continue the euphyllary forma-
tion directly from the cotyledons, without ever producing
cataphyllary leaves either on the main or the lateral
sprouts; perennial Dicotyledons, on the other hand,
mostly descend from the original leafiness to cataphyllary
formation, and this either on the main sprout itself, as in
Adoxa, Helleborus niger, Hepatica, and Anemone nemo-

* The first leaves of the sprouts have been compared with the cotyledons
of the main sprout, a ground for which is indeed to be found in their position,
but only rarely in their forms.

30 THE PHENOMENON OF

rosa; or on the lateral sprouts arising from the axils of
the cotyledons and the euphyllary leaves next succeeding
these on the main sprout, in which case the main sprout
dies down either entirely, or at least in the upper part,
and this indeed mostly without having carried its develop-
ment up to blossoming; while the lateral sprouts last
through the winter in the form of basilar buds or ranners
penetrating into the soil, and in the second year bring
forth a more vigorous generation, mostly advancing to
the terminal point, blossom and fruit. This is the condi-
tion, for instance, of most of the perennial species of Aster,
Solidago, Achillea, Tanacetum, Mentha, Lysimachia, Hy-
pericum, Epilobium, Lythrum, &c.; Owxalis stricta and
Solanum tuberosum also belong here, in which the parent
stem dies entirelyaway, and onlythe ends of the runners live
over the winter as the foundations of a new, more vigor-
ous generation. It is well known that the potato raised
from seed does not usually flower, or only exceptionally.
Perhaps, however, Physalis Alkekengi affords one of the
best examples of this kind. Between the stalked, broadly
lanceolate cotyledons of this plant, spreading out above
ground, rises In germination a stem about a span high,
with twelve or thirteen (euphyllary) leaves, increasing in
size upwards, and when winter approaches this stem dies
down without having flowered. In the axils of the
cotyledons and the succeeding leaves standing close
down to the earth, in the course of the summer, while
the sterile main sprout is being developed further up-
wards, arise buds, which, scarcely a line long, turn their
points at once obliquely downwards, and subsequently,
becoming more and more elongated, penetrate almost
perpendicularly into the earth. They are clothed with
distant, clasping, apiculated, cataphyllary leaves, beut
inwards like a cap at the tips, and these are reddish
above ground, whitish beneath. The uppermost of these
sprouts penetrating into the earth and laying the founda-
tion of the more vigorous and fertile generation of the
second year, begin again with small, dwarfed, euphyllary

REJUVENESCENCE IN NATURE. 3l

leaflets, and descend gradually on the tips penetrating
into the earth to cataphyllary leaf-formation.

The anticipatory condition of the sprout is no less
frequent than the retrogressive. It occurs, for example,
where we see flowers arise without bracts (Vordlätter), or
with such leaves as belong to the hypsophyllary leaf-
formation, from the axils of euphyllary leaves, as in
Linaria cymbalaria, Lysimachia Nummularia, Tropeo-
lum, &c.

More important for our purpose is the consideration of
the deficiencies of the sprouts in the upper part, i.e. in
reference to the formation with which they close. Not
every sprout carries the developmental series, whether it
take it up lower down or higher up, to its termination in
the formation of flower and fruit ; but certain determinate
sprouts remain fixed at determinate subordinate stages,
beyond which they have no power, or only in extraordinary
cases, to advance ; nay, there are even cases where instead
of an advance to the final term in the building onwards
of the sprout, a retrogression of the metamorphosis takes
place, which is frequently followed by a periodical vibra-
tion up and down of the formations, connected with the
changes of the seasons. So, for instance, in the oak, the
beech, and the chesnut, the sprouts of which produce
cataphyllary and euphyllary leaves in regular alternation
from year to year.”

These limitations downwards and upwards, which de-
termine the history of the individual sprout, in contra-
distinction to the history of the life of the entire plant,
form the most essential causes of the infinite multiplicity
we meet with in the formation of sprouts in vegetables.
Far removed, therefore, from merely subserving to an
asexual increase and a multiplication of identities, the
plant rather developes its great multiplicity in this very
formation of sprouts, and thereby becomes a “ vegetable”

* The same is the case with Adoxa, which creeps along the ground and
rises and descends in undulations with the alternation of euphyllary and
cataphyllary formations.

32 THE PHENOMENON OF

(Gewächs), i.e. a whole composed of subordinate indi-
viduals.

Lastly, the subordinate import of the sprout is ex-
pressed, ¢/ird/y, most distinctly in their reciprocal com-
pensations. For how were it otherwise possible in the
frequently so one-sided endowment of the sprout, limited
to a few, nay often to a single formation? A mere cata-
phyllary sprout necessarily requires the appearance of
euphyllary formation in another series of sprouts, and
when these again do not proceed as far as the formation
of hypsophyllary leaves and flowers, further ranks of
sprouts must be introduced. Thus in the pine we find on
the main-shoot and the branches resembling it (in the
earliest youth of the germinating seedling excepted), only
scale-like cataphyllary leaves; the euphyllary formation
so requisite to the tree is committed to a second order of
sprouts, to the little branchlets which bear the two, three,
or five-fold bunches of aciculate euphyllary leaves. These,
however, produce neither flower nor fruit; it is a new
rank of sprouts which produces the staminal leaves
(stamens), and again, another which forms the foundation
of the cone, on which, as the last formation of sprouts
appear the fruit-scales, in the axils of the bracteal scales
(hypsophyllary leaves) of the cone. ‘Thus the pine has
five qualitatively different orders of sprouts, or, if we
count as a separate rank the main-sprout or trunk, dif-
fering in its earlier behaviour from the branches which
form the crown of the tree, even six.

The most important and interesting point revealed by
these investigations, is the definite order of generation in
which the different ranks of sprouts proceed one out of
another. Only a small proportion, namely, of (Phanero-
gamic) plants, reach the goal of the metamorphosis,
blossom and fruit, in the first generation ; the majority
attain this term only in the second, third, fourth, or some-
times not until the fifth generation of sprouts.* Every

* If we include the seed-bud (ovule) as the last generation of sprouts, we
have, for all plants which do not possess a “ terminal” or “central” ovule, a

REJUVENESCENCE IN NATURE. 33

vegetable species has its specific law in this, and some-
times even nearly related species are distinguished by
their character in this respect ;* more frequently, how-
ever, the species of a genus, nay even the genera of a
family, follow essentially the same order in the production
of sprouts. Thus, for instance, the Grasses, Cyperacee,
Orchidex, Labiate, Scrophularinee, Primulacez, Cruci-
feree, Onagree, Malvacex, Dipsaceze, and Composite,
never attain the flower in the first, mostly in the second,
but sometimes not until the third generation ; the Plan-
tagineze, as well as the majority of the Scitamines,
Amentaceze, and Leguminosz, mostly in the third; a
few of the last, as Phaseolus, Apios, Hedysarum corona-
rium, and Trifolium montanum in the fourth. But this
enumeration of the essential generations of sprouts, or,
as they may be called, the system of axes of the plant,
merely marks the most general outlines of conditions
which include an infinite multiplicity of subordinate cases.
The number of the axes being equal, they divide, in the
first place, according to the distribution of the formations
on the axes in question. Especiallyimportant in this respect
is the behaviour of the last axis, which bears the flower.
Whether the last axis sets the flower cmmediately,t or
after the preceding formation of a definite number of
leaves, or, finally, an endefinite number of leaves precede
the flower,$ are distinctions of importance even as
characters of families. But also with like distribution of
the formations, further distinctions occur in reference to
the region from which the next system of the axes arises ;
as also, lastly, less essential ones, of great importance
however in regard to the habit of the plant, in respect to

still further term in the series of generations, and the really uniaxial plants
are then reduced almost to none.

* Note the genera Echium, Arabis, Sagina, Silene, Potentilla, Viola,
Lysimachia, Veronica, &c. See the Ratisbon ‘Flora,’ 1842, 692.

T Cyperacex, Orchidex, Crucifere, Balsaminex, Primulaces.

+ Graminee and Iridee have one bract (Vorblatt); Labiate, Scrophu-
larinee, Lythrariee, and Leguminose, have two; Gesneriacex have three.

$ Polemoniacew, Zigustrinee.

3

34 THE PHENOMENON OF

the number of the co-ordinate sprouts of each rank, the
region and the abundance in which the said formations
occur on the various axes, the relative dimensions of
these axes, &c. A few examples placed side by side for
the sake of comparison, may render these further dis-
tinctions more clear.

Paris quadrifolia and Lysimachia Nummularia, both
have a two-membered chain of sprouts; but the endow-
ment of the two axes is quite different. In Paris, i is a
cataphyllary sprout creeping underground ; ii, brings forth
successively a basilar cataphyllary formation, the euphyl-
lary formation, and the flower. In Lysimachia Nummu-
laria, 1 is a creeping euphyllary sprout; ii, immediately
produces the flower.

Convallaria majalis and Convallaria multiflora have
both three-membered series of sprouts, both also have the
sume distribution of the formations, namely, on axis 1,
the cataphyllary and euphyllary formation ; on ii, the
hypsophyllary formation ; while im concludes with the
flower. But they are distinguished in the relations of the
emergence of the shoots ; in Convallaria majalis, ii, arises
from the cataphyllary region of 1; in Convallaria multi-
fora from the euphyllary region. They differ, moreover, in
reference to the number of the co-ordinate sprouts, since
Convalluria majalis possesses only a single sprout of the
second generation, thus only one inflorescence; Convallaria
multiflora numerous inflorescences, but less numerous
sprouts of the third generation, 7. e. only afew flowers in
each inflorescence. Cyclamen and Centunculus both have
two-membered series of sprouts, both the same distribution
of the formations and the same regions of origin of the
sprouts: 1, being a euphyllary sprout ; ii, blossoms from
the axils of the euphyllary leaves. Here the relative
dimensions are the principal causes of the very different
habit. In Cyclamen, i is a tuberous stock; ii, the
blossom, on the other hand, has an elongated stalk ; in
Centunculus, on the contrary, i is a delicate little sprout,
while the flower is almost sessile.

REJUVENESCENCE IN NATURE. 35

Plantago major and Impatiens Balsamina owe their
very different habit, in like manner, principally to the
different relative dimensions. In both, i is a euphyllary
sprout ; in both the ii, hypsophyllary leaf bearing sprouts
(the axes of the inflorescences), arise from the axils of
the euphyllary leaves ; from the axils of the hypsophyllary
leaves (bracts), finally, i in, the flowers; but i is a short
stock in Plantago, forming a rosette upon the ground.
In Impatiens it is a very much elongated sprout; ni, on
the contrary, is a sprout in Plantago, especially elongated
in the lowest part, and thereby forming the shaft, or
rachis, as it is called. In Jmpatiens, on the contrary, it
is an extremely short stalk, thus hidden in the axil of
the leaf; iii, the flower, is sessile in Plantago, and fur-
nished with a long stalk in Jmpatiens. In ü is to be
added the distinction in reference to the abundance in
which the formation occurs, for in Plantago a great
number of hypsophyllary leaves exist, laying the founda-
tion of a rich spike; while in Jmpatiens there are but few
hypsophyllary leaves, which is the cause of the poverty of
blossom in the small axillary cyme.

The complementary relations of the sprouts become
still more manifold through the superaddition of a division
of a generation, to the consecutive series of generations,
which can start from any generation contained in the
vegetable “stock,” but in many cases appears even in
the first generation, produced by sexual propagation, and
then gives rise to the existence of two ditferent comple-
mentary “stocks.” The latter is the case in all dicecious
plants, the former in the monoecious, unless the case
occurs of the terminal structures distributed to the two
kinds of flowers being attained by a simple series of
generations. Cases of moncecia through division of gene-
ration, so that one part of the sprouts belonging to the
same generation terminates (immediately, or even in the
second or third line) with male flowers, another portion
with female flowers, occur in Pachysandra, Arum, Sil-
phium, Calendula, and Eriocaulon, in which the flowers

36 THE PHENOMENON OF

belonging to the same spike or the same capitule, 2. e.
arising from the same parent axis and thus forming only
one generation, are partly male (the lower or outer) and
partly female. ‘The Hornbeam (Carpinus) may furnish
an example of a more complicated case. Male and female
catkins arise as co-ordinate sprouts from the same parent
axis, but the male flowers form the second generation on the
male catkins, the female blossoms the third generation on
the female inflorescences. ‘The division of the generations
occurs therefore here in the last generation but one for
the males, in the last but two for the females; the two
kinds of catkin are, to a certain extent, themselves again
“ stocks” upon the “stock,” the male “stock” (catkin)
with two-membered, the female with three-membered
series of generations.* Examples of moncecious condition
through mere succession of generations are furnished by
many Euphorbiacee, for instance, Zuphorbia and Buxus,
where the male blossoms are produced as lateral sprouts
from the sprouts terminating with female flowers.
Besides the sprouts which present themselves as essen-
tial members of succession of generations and of division
of generations, and consequently are necessary to the full
carrying out of the series of formations up to blossom
and fruit, most plants possess other sprouts, which are
not necessarily connected here, and therefore may be dis-
tinguished from those hitherto examined, under the name
of inessential sprouts. In plants which possess terminal
flowers, z.e. in which the main-sprout terminates in a
flower, all the lateral sprouts, however numerous and
regular they may be, are to be regarded as inessential.
The inessential sprouts enröch the “stock” within the
annual period of vegetation, if they succeed the main
sprout quickly in their development, as is the case, for
example, among annual plants (summer plants) with
all the sprouts; in herbaceous perennials with the

* It is similar in Quercus, only here both the female and the male flowers
form the sccond generation within their inflorescences.
T Sarcococca exhibits the reverse.

REJUVENESCENCK IN NATURE, 37

upper sprouts. If the sprouts remain undeveloped, as
buds, until the commencement of a new period of vege-
tation, they maintain and renew the plant, while the old
a stock, ” m so far as it bears such buds capable of
development, does not die away, as is seen in perennial
herbs, half-shrubs, and true woody plants, in which less
or greater, merely underground or also an above-ground
portion of the “stock” is preserved. ‘This gives the pos-
sibility for the plant to rise up in new generations from
the same stock, year after year, and thus repeatedly to
produce flower and fruit. Finally, if such inessential
sprouts become detached, whether by dying away of the
old “stock,” as in the monk’s-hood (Aconitum Napellus),
the potato, and many bulbous plants ; or, the old “ stock”
persisting, by a natural solution of the connection with
it, as in the young plants springing from the runners of
the strawberry,—the sprout becomes a new “stock,” and
appears as a multiplying sprout, as a natural layer. All
these modifications may occur in one and the same plant.

Thus the common spurge (Huphorbia Cyparissias), ex-

hibits two kinds of enrichment-sprouts above ground,
namely, in the euphyllary leaf region, the densely-leaved
spreading, mostly barren euphyllary sprouts, which give
‘the characteristic fulness to the euphyllary region of this
plant; in the hysophyllary region, further, the branches
of the umbels arising from the circle of hypsophyllary
leaves beneath the small terminal capitules, with further
bifurcated and scorpioid ramifications of their branches,
forming the rich and finely compound infloresence of this
plant. Below the ground, in the cataphyllary region,
occur in summer numerous small, reddish-white, little
buds; these are the sustaining and renovating sprouts of
the plant, arising with a cataphyllary formation, advanced
somewhat in development, and destined to shoot up in
the next year and renew the “stock.” Other little
sprouts, finally, not unlike these, are met with here and
there on the branches of the root approaching the surface
of the earth, where however they assume an independent

38 THE PHENOMENON OF

character, through forming roots of their own, and sooner
or later become detached from the parent “stock,” thus
presenting themselves as increase-sprouts or layers.

All these modifications in which the inessential
sprouts occur, agree in the circumstance that they re-
present, in greater or less extension, only repetitions of
that which the plant possesses in its essential sprouts.
They lie outside the straight line towards the flower and
fruit, being interposed laterally, at various heights, as ines-
sential lines of repetition. In many cases the presence
or absence of such repetition-sprouts, appears, usually,
as something accidental and indifferent to the plant, as
for instance, when the tulip stem acquires a branch with
a lateral flower. In general, however, these repetition-
sprouts are of more importance, and are more necessary to
the plant than might appear, so that they must be regarded
as in certain respects essential, thus, namely, in reference
to the characterisation and also to the economy of plants.

That the repetition-sprouts are characteristic, is ex-
pressed generally by their influence on the “habit” of
plants, on the architectural design of the “ stock,” whether
as a whole, or in its separate parts, as in the inflorescence
especially. Entering more into particulars we find
characteristic features in the arrangement and direction
of the branches, in the frequently peculiar arrangements
of the leaves and rudimentary traces of such arrangements
on the branches, in the laws of curvature of the lines of ar-
rangement of the leaveson rudimentary branches, especially
in the laws of antidromy occurring on the branches placed
symmetrically opposite to each other, in the relations of the
subtending leaves to the branches, particularly the con-
ditions of fusion of the two, &e. A multiplicity of good
and important characters would be altogether lost if the
inessential branches were removed; nay even the mere
presence or absence of certain modifications of them, as
of subterranean or above-ground bulbels,* stolons,t

* Thus in the genus Suaifraga ; in 8. granulata, and S. bulbifera.
T See the genera Carer, Kpilobium, Ilieracium, Valeviana, Viola.

REJUVENESCENCE IN NATURE, 39

above or below the earth, with or without tuberous struc-
tures, spine- branches,* &c., are characteristic of particular
species of plants. ‘Thus, in spite of the distinction between
essential and inessential sprouts, we must acknowledge,
that from a higher point of view all sprouts appear es-
sential. As it is not merely in the last stages of the
metamorphoses that the life reveals its peculiarities,
since every one of the lower stages also turns outwards
a special side of the living essence, not only are those
sprouts which bear relation to the attainment of the goal
of the metamorphosis to be called essential, but also,
everything else in the collective circle of those structures
which are destined to represent the plant on all sides, and
cannot be removed from that circle without essential interfe-
rence with the characterisation of the plant. A fewexamples
may render more clear the importance of the inessential
or repetition-sprouts in the characterisation of the plant.
The peculiar forms of the crowns of trees, for instance
of the pyramidal poplar, of the cypress, depend upon the
proportion of the vigour and abundance of the repetition-
sprouts to the main sprout or trunk of the tree. ‘The
relation of arrangement shows itself more distinctly in
many Conifers, where the repetition-sprouts over-leap
certain tracts which reınain without branches, and form
tolerably regular whorls. In Pinus the tracts between
the larger, whorled branches are occupied by the small
(essential) leafy branchlets. Essential and inessential
sprouts occur in extremely regular alternation in 7ro-
peolum minus, when every third flower-sprout is followed
by a euphyllary leaf sprout. When there is 2 arrange-
ment of the leaves on the main-shoot, the euphyllary leaf
sprouts derive from this an arrangement according to
2 in the reverse direction. Here also may be mentioned
the peculiar cases where the leaves having a many-ranked
direction, the branches are nevertheless in distichous
arrangement, on account of only part of the leaves pro-

* See Prunus, Pyrus, Cratagus, Rhamaus.

40 THE PHENOMENON OF

ducing branches in their axils, as in the Arbor Vite
(Thuja), and several of the branched Mosses, for instance,
Hypnum abietinum, delicatulum, tamariscinum, &e. Hence
arise pinnate forms of ramification, which frequently stop
at a determinate degree of pinnation ; as in the three
species of Hypnum just named, the first is simply, the
second doubly, the third triply, pinnate. In the Horse-
tails we see a determinate degree of ramification kept to,
even in a verticillate arrangement of the branches.* If
we take the characteristic branches away from such a
plant, it would lose its peculiar “habit.” Imagine, for
instance, a Tamarisk (Zamariv) robbed of its numerous
minutely-leaved euphyllary leaf twigs, and the fine bushy,
thousand-leaved, pyramidal shrub becomes a simple,
meager, naked rod, on which the distant, minute leaves
are scarcely visible. Even characters applicable to generic
distinction may vanish through removal of inessential
branches. All the lateral spikelets of Zolium and Triticum
are inessential, insomuch that a terminal spikelet exists ;
but with their removal is wholly lost the distinction be-
tween the two genera, founded on the different commence-
ment of the branches of these lateral spikelets. Thus also
would one of the most important distinctions between the
genera Festuca and Bromus become imperceptible through
the disappearance of the panicle-branches, namely, the
one-sided direction of the first secondary branch, which
principally distinguishes Festuca from Bromus. But
inflorescences above all show most distinctly what im-
portant and weighty characters of plants are expressed
by mere repetition-shoots. All inflorescences having a
terminal flower, evidently consist, with the exception of the
main axis of the inflorescence terminating in that flower,
of repetition-sprouts ; and yet what distinction, what mul-
tiformity of structure, exists in these inflorescences ! What
a distinction, for instance, between the simple raceme of
Henyanthes and Berberis, the umbel of the coriander,

* Eyniselum arvense wd E. sylvalican.

REJUVENESCENCE IN NATURE. 41

the pyramidal panicle of the lilac (Syringa) or the phlox,
and, finally, the anthele of Luzula and Ulmaria, rendered
so remarkable by the strong development of the lower
flower branches. But the essential lateral parts of the
spiked or racemose inflorescence may be developed to
most characteristic forms of the inflorescence, by inessen-
tial sprout-formation from the bracts (Vordlätter), e.g. to
the forked form, by the equilibrium of a homodromous
and antidromous sprout, to the screwed form by the pre-
dominance of the homodromous, to the scorpiord form by
the prevalence of the antidromous sprout. All these
characteristic forms are produced by mere succession of
inessential generations, which proceed one out of the other
according to determinate laws, and are frequently inti-
mately chained together into apparently continuous axes
(sympodia).

Another side, on which the sprouts which have been
termed inessential in the foregoing, appear in a deep and
essential connection with the course of existence of the
plant, is their relation to the economy of vegetable life.
Formation of sprouts, generally, especially however the
formation of inessential sprouts retrograding to the lowest
stages of the metamorphosis, gives the plant the means of
attaching itself to the most varied conditions, of persisting
through periods of continued cold and heat, damp or
drought, according as the climate may produce, and
guarding against death in all cases of frustrated seed-for-
mation. Under the varied circumstances which may frus-
trate the fertilisation, under the readily possible prevention
of the formation of seed after fertilisation has taken place,
it is of importance, since the proper individual of the
plant (the simple sprout) can only once flower and ripen
seed, that the “stock” should have the capacity, by
another kind of propagation, namely, the formation of
sprouts, of repeating the blossoming and ripening, either
in the same period of vegetation,—whereby, for example,
in every many-flowered inflorescence, any temporary dis-
turbance loses its effect upon the whole through succes-

42 THE PHENOMENON OF

sive opening of the flowers, which is especially important
in the case of annuals,—or in a succeeding period of
vegetation. The latter condition is particularly important
for such plants, as, in consequence of the contrivance of
the organs of fertilisation, rarely bear fertile seed, as 1s
the case with most of the Orchideze,—as also for such as
through their situation are often prevented from flowering
for a long time, as is the case with many water-plants,
when the level of water remains long very high. Thus
Littorella lacustris, which never flowers under water,
maintains and increases itself by lateral runners, year
after year, at the bottom of the lakes of the Black Forest,
and only comes into flower when the water retreats, in
the driest years, which scarcely recur oftener than once
in ten. Similar conditions are exhibited by many nemoral
plants, as for instance, the woodruff; when the shade of
the wood is too dense, or even when too free an opening
of the wood interferes with its flourishing above-ground, it
maintains itself many years without flowering by subter-
ranean runners, waiting from generation to generation
the return of a season favorable to its success. The well-
known phenomenon that annual plants almost entirely
disappear in the extreme north and in the Alps, likewise
deserves to be mentioned here, since it shows how, in
proportion as the ripening of seed is endangered by cold,
a formation of sprouts adapted to the persistence through
the cold season takes place. Lastly, the formation of
sprouts is of especial importance for hybrid plants, which
as a rule can only be maintained and increased by
uaturally or artificially detached sprouts. The frequent
experience that hybrids of annual or biennial plants, e. g.
the hybrids of the genus Verbascum,* acquire a duration of
ınany years through continued formation of sprouts from
the old “stock,” is a speaking testimony of the inter-
position of sprout-formation in cases where propagation
by seed is difficult or impossible, since in this instance

* I have observed this phenomenon also in the hybrid between Guothera
biennis and wuricata, not unlyequent in the district of Freiburg.

REJUVENESCENCE IN NATURE. 43

the longer maintenance of the hybrid form is effected by
a sprout-formation, not merely inessential in the sense
above denoted, but also quite extraordinary, and alto-
gether absent in the parents of the hybrid.

To these indications respecting the connection of the
inessential sprouts with the economy of vegetable life, we
have to add also the consideration of certain cases, which
completely remove the sharpness of the former distinction,
since, as cases of transition, they may be taken in two ways.
In contrast to the essential sprouts, which, as determinate
series of subordinate generations in which the metamor-
phosis of the plant is carried to its term, represent,
according to number, a firmly fixed system of axes, each
successive one bringing something new—we have called
the inessential sprouts, lying outside the series and inde-
finite in number, repetition-generations. But cases occur
of real repetition-generations, which do not lie outside
the line, but belong to the series of transition generations
necessary to the attainment of the goal. Here refer the
strengthening generations—already noticed above*—of
many perennial plants, which in the first year are still too
weakly to form flowers and fruit. The fortification to
the point of fruitfulness may occur either in the next
succeeding generation, otherwise essentially like the first,
or deviating only in a retrogression to cataphyllary leaf-
formation, and thus in the second year, if every gene-
ration is destined to a year’s duration,—or, more or less
numerous, and then mostly numerically indeterminate,
in all essentials completely similar generations, may suc-
ceed one another, till at length that age of the “ stock”
is attained in which it advances to the formation of
blossom. The latter condition occurs especially frequently
in trees, and indeed most distinctly in those which haye
no terminal buds, and consequently, in the strictest sense,
unfold each new year a generation composed of un-
doubtedly new individuals (evident lateral buds). ‘Three

* See pp. 29, 30.

44 THE PHENOMENON OF

examples, very unlike, but agreeing in the conditions
here referred to, the asparagus, the lime, and the vine,
may be examined a little more minutely, to illustrate
this point.

The common asparagus (Asp. officinalis) differs from
other perennial herbs formerly mentioned which arrive at
blossom only through strengthening generations, in the
circumstance that it produces several strengthening
generations in one and the same year, three or four in
fact even in the first year, while in the succeeding years
the number of generations sprouting out of one another,
in one summer, amounts to eight or ten. The single
shoots of asparagus are namely, really so many successive
generations, and not as it might appear co-ordinate mem-
bers of one and the same generation, since the horizontal
root-stock is not a continnous axis, but a sympodium
formed by the chaining together of the basilar portions
of the individual shoots. Each succeeding shoot. arising
from the axil of the second, sub-basilar cataphyllary leaf
of the foregoing, hidden in the ground, is related anti-
dromously to the foregoing, like the successive flowers
of ascorpioid inflorescence. From the first shoot, arising
from the seed, which is the weakest of all, and sends
out the second, already somewhat stronger, from the
axil of the first leaf after the cotyledon, the shoots
produced in scorpioid succession out of each other, in the
above-described way, increase in strength till about the
fourth or fifth year, when the asparagus has attained its
perfect vigour, which remains pretty equal for about
fifteen years, and then again gradually decrease with age.
A subordinate reaction occurs during this, the last. shoots
of each year decreasing somewhat in strength. The
shoots of the first, and often even of the second year, are in-
fertile, for the asparagus does not usually flower until the
third year. Since three or four shoots are produced in
the first year, and five or six in the second, the asparagus
requires a series of eight to ten generations to strengthen
it up to the point of hearing. All gencrations, both

REJUVENESCENCE IN NATURE. 45

the earlier infertile and the later fertile ones, are essentially
alike in all other respects. ‘lhe first shoot bears, after
the cotyledon, a basilar, subterranean, amplexical sheath-
ing leaf, then in the upraised stem distant smaller and
narrower scale-like Jeaves, which might be taken for
hypsophyllary leaves if they were not preferably to be re-
garded as cataphyllary formations, since it is their axils
that the aciculate, leafless branchlets, arise, which here,
as in Ruscus, take the place of the euphyllary leaves. The
shoot thus exhibits two essential axes, the main axis with
two gradations of the cataphyllary formation, and the
leafless lateral branchlets, which represent the euphyllary
formation, and are mostly enriched by others similar
(inessential), whence arises the tufted arrangement of
these last branchlets. These two essential axes are re-
peated in all the succeeding shoots, only progressively
more vigorously and richly through the increased number
of leaves on the main axis, and through the occurrence of
inessential lateral branches, which repeat the upper part
of the main axis, and, finally in the most vigorous shoots
produce again lateral twigs of the second, third, or even
of the fourth degree, whence arises the stately panicled
growth of the asparagus. The essential axes are not mul-
tiplied by this enrichment until the flower, which arises
on each side from the basis of the branches, appears as
the third essential sprout-formation of the asparagus.
The bearing shoot of the asparagus has thus three different
and essential systems of axes or generations of sprouts,
but appears, itself, as a whole, only after a series of gene-
rations resembling itself, but barren, which are indeed
repetitions of the like, but nevertheless essential prepa-
ratory or transition links.

Like the root-stock of the asparagus, the stem of the
lime is also a sympodium ; for the lime, from the first
annual shoot of the germinating tree onwards, never pro-
duces terminal buds, the stem being developed forth from
year to year from the uppermost lateral shoot. The lime,
when raised from seed, grows very slowly, and does not

46 THE PHENOMENON OF

flower until it has attained an age of full thirty years ; so
that the number of necessary strengthening generations
is considerable here. When the bearing age is attained,
the flower appears in the blossoming generation as the
third axial system, since it arises out of the axil of the
winglike first leaf of the lateral buds.

The relations of the strengthening generations are
much more complicated in the vine. The germinating
vine produces first two small leaf-like cotyledons, and
then a weak, upright shoot, scarcely a span high, with seven
to ten, seldom more, euphyllary leaves, which are arranged
spirally according to the 2 or 4 order. It is pro-
bable that a weak tendril-formation occurs at the summits
of vigorous seedlings, and beyond this an apparently di-
rect continuation from the uppermost euphyllary leaf, as
we are enabled to make out more clearly on the shoots of
the succeeding year ; but the whole of this uppermost por-
tion acquires, in any case, but a very slight development,
and dies at the top as the winter comes on.* This first
main-sprout of the seedling forms the basis of the so-called
head (ceps, in French), from which arise the climbing
shoots (Freb-schosse), following in the second year; but
these are produced through a peculiar agency. In the
axils of the euphyllary leaves, namely, (nay even of the
cotyledons,) buds are formed, on which we find, first a
cataphyllary leaf, then a euphyllary leaf, and the trace of
a tendril, which latter organs, as well as those following
further on, are mostly very stunted in their development,
or even wither up before fully unfolded, while a new bud
is formed in the axil of the cataphyllary leaf, which be-
comes more swollen than the chief bud, and is protected
by its own two cataphyllary leaves (bud-scales). In this

* Unfortunately I have no seedlings of the vine at disposal at present.
On those ul observed I noticed no formation oftendrils, but have seen
this in the radical sprouts (suckers), which behave just like the seedlings in
the arrangement ofthe leaves and otherrespects. The statements as to the
conditions of the lateral axes of the first and second year are also derived
from the latter. (The supposition mentioned above was not confirmed by
later observation. See author’s preface, Trans.)

REJUVENESCENCE IN NATURE. 47

way, if the chief bud is not unfolded, there arises the
appearance of two buds placed side by side, one drying
up and the other fresh. The stuntedly developed chief-
buds are no other than the first “@eitzen’” of the vine,
which are repeated in a more distinct manner in the fol-
lowing years; from the lateral buds, on the contrary, are
developed in the next years the first “‘Zotten”’ of the vine,
which at once grow out more vigorously and more slender
than the head-shoot of the seedling, and, as the preceding
statements indicate, arise from the base of the stunted
“ Geitzen,” and not directly from the middle-shoot, thus
representing properly a secundane, a ramification of the
second degree. The ‘“Zotten” differs from the head-
shoot in many respects; they have never spiral, but
always distichous arrangement of the euphyllary leaves ;
they bear numerous tendrils, or “forks,” as they are
called ; and, what is most important here, a minute ex-
amination shows that they are never simple, but linked
sprouts, forming a sympodium. It is well-known that
the tendrils of the vine stand opposite to the euphyllary
leaves; this is explained by the fact that the tendril, as
the temporary apex of a sprout, becomes turned towards
the side by the succeeding sprout, arising from the axil
of the uppermost euphyllary leaf, while the new sprout is
attached upon the euphyllary region, as an apparently
direct prolongation. Another point especially worthy of
remark in this is, the regular alternation in the character
of the sprouts linked together to form a “Zo/te,” occurring
after the first member of this series of sprouts. The first
sprout with which the “ Lotte’? commences is different
from all the succeeding, since it commences with a cata-
phyllary formation (with the two basilar bud-scales,
visible even in the first year), and after this produces
mostly more than two (3—5) euphyllary leaves, before
it terminates with the formation of the tendril. The
tendril, like all the succeeding tendrils, bears a hypso-
phyllary leaflet, from the axil of which arises a branch,
which gives the tendril the well-known forked form. All

48 THE PHENOMENON OF

the succeeding sprouts (members of the series of genera-
tions of the “ Lotte’’) are added upon the foregoing with-
out repetition of the cataphyllary formation, and possess
alternately one and two euphyllary leaves before the transi-
tion to the formation of the tendrils. From this arises quite
a peculiar arrangement of the tendrils, which are arranged
distichously, but in such a manner that two successive
tendrils always fall on the same side, since every third
leaf of the “Zotte” is without an opposite tendril.* It
is further to be remarked, that the imposition of the dis-
tichous arrangement of the leaves occurs with prosenthesis
on the first or basal sprout of the “.Zotte,” while all the
following commence without prosenthesis ; hence arises
the uninterrupted continuation of the distichous arrange-
ment of the euphyllary leaves, through the whole chain of
sprouts of the “.Zofte,” while at the origin of the “ Zotte”
occurs a crossing of the ranks with the subtending leaf
(the basilar cataphyllary leaf of the “Getz.” In the
axils of the euphyllary leaves of the ‘“Zotte” new buds
are formed, unfolded more or less perfectly during the
course of the summer, and representing the branches of
the “Zotte,” which have a connection similar to the
“Lotte” itself, ©. e. are in like manner chains of sprouts.
They are weaker than the “ Zotfe” from which they
arise ; very often only very poorly developed, especially
on the lower parts of the “Zotten.’ These are the true
“Geitzen’’ of the vine, which we met with in a yet almost
irrecognisable condition of development on the principal
shoot. They form the second annual series of generations,
and are distinguished from the “Zotten” by their basal
sprouts possessing constantly only one cataphyllary leaf
and two euphyllary leaves. Although all “@eitzen” are
of similar nature, they originate in two ways, part,
namely, are primary axillary sprouts (those from the axil
of the lower euphyllary leaf of the two-leaved joints of
the “Zotte”); part secondary (accessory) axillary sprouts

* I have found this constant, not only in Vitis vinifera but also in several
American vines.

REJUVENESCENCE IN NATURE. 49

(those from the axil of the upper leaf of the two-leaved
and of the single leaf of the one-leaved joints of the
“ Lotte’). Therefore, on the two-leaved joints of the
“ Lotte” the secondary sprout from the upper leaf-axil
behaves like the primary sprout from the lower, while it
is essentially different from the primary sprout of the
upper, since the primary sprout (which carries on the
Lotte’’) is added on without a cataphyllary leaf and without
prosenthesis, and the secondary sprout (which forms the
“Geitz”) begins with a cataphyllary leaf and with
prosenthesis. The ‘Zotten” grow all through the sum-
mer, and often on until late in autumn, forming a chain,
endless in its nature, which is only forcibly broken off by
the commencement of winter. I have counted as many
as twenty-six constituent joints (thus twenty-six tendrils
and about forty leaves) in strong “ Zoftten.” The
“Geitzen” also die away at the point in winter; the
weak and late developed often even down to the base, so
that only the cataphyllary leaf with its axillary bud
remains. ‘This lowest part of the “Gedtz” is of especial
importance. In the axil of the basilar cataphyllary leaf
of the basal-sprout of the “Geitz,” is found a bud (as
stated above, in describing the condition in the first
year); this bud begins with two firmly-connected cata-
phyllary leaves, and endures through the winter in the
closed condition. It is this resting-bud from which the
series of generations of the “Lotte,” and indirectly the
formation of “Geitzen,” is repeated in the next year.
It is, therefore, first of alla “Zotfe”’ bud, and, if the vine
has attained the proper age, which is usually in the fifth
or sixth year, at the same time a bearing bud, since the
inflorescence appears at the lower parts of the “Zotie”
in place of the previous tendril-formation. In this case
numerous hypsophyllary leaves occur in place of the
single hypsophyllary leaf of the tendril, and the axis ends
in a terminal flower; by graduated ramification from the
axils of the hypsophyllary leaves arises, then, the richly
panicled blossom of the grape, which, in opposition to

50 THE PHENOMENON OF

ordinary botanical language, is commonly called a
“ traube’ (raceme).

When we seek to separate the essential and inessential
sprouts, in this complicated biography of the vine, which
could only be given in very rough outline here, we might
be inclined to see in the repeated succession, not of mere
simple generations, but even of whole chains of genera-
tions, as occurring in the “Geitzen” and “Lotten,”
clearly essential arrangements of sprouts, because the
same are necessary transitional links to the attainment of
flower and fruit; but if we take the essential succession
of sprouts, in the sense explained in the preceding pages,
as a series of partially endowed, reciprocally complemen-
tary sprouts, we must rather acknowledge that the vine
is essentially only wxiaaial, since it produces all the
essential stages of metamorphosis on one axis, as we see
them represented in the basilar sprout of the fertile
“Lotte,” which includes cataphyllary, euphyllary, hypso-
phyllary, and flower formations. All the rest of the
members of the succession of sprouts are either prepara-
tory representatives of the same series of formations not
fully attaining the goal, or imperfect repetitions of these.
But how characteristic is this varied rise and repetition,
this linking into a complicated succession of sprouts, in
the developmental history of the vine, and how essentially
it lays down the conditions under which this plant can
live and grow! It is true that if we compare the ordi-
nary methods of cultivation, adapting the vine to our
conditions by systematic crippling, we might wonder at
the abundance of superfluity which the vine annually
produces. ‘The “Geitzen” are carefully broken off, and
the long luxuriant ‘“Zotten” cut back to a few joints!
In the south, on the other hand, when the vine appears
as a widow, when not supported by the lofty elm, we see
how this superfluity essentially belongs to the economy of
the vine; when left to its freedom, it twines itself over
the highest trees.

Thus, then, we see that much as the law of superfluity

REJUVENESCENCE IN NATURE. 51

prevails in the formation of sprouts in plants, as it does
everywhere in nature, yet all formation of sprouts, the
inessential no less than the essential, possesses a deter-
minate relation to the maintenance and progressive de-
velopment of the plant. From the consideration of the
sprouts as individuals, the vegetable “ stock”’ must appear
to us as the living trunk of a family, rejuvenised and in-
creased according to determinate laws of propagation,
the differently gifted members of which family we have
endeavoured in the foregoing, though only in mere
indications, to represent, as arranged according to descent
and collateral relation, in their either closer (direct) or
looser (indirect) relation to the destination of the whole.*
And thus may the import of sprout-formation become
clear, as a subordinate propagation, subserving the indi-
vidual destination in its wider sense. ‘The undeniable
interweaving of propagation and development within this
circle, may at the same time form an acceptable guide to
the destination of the individual in the larger circle of the
species, as well as that of this again in the totality of the
series of organic creation,t which has already been re-
ferred to in the Introduction.

II.—LEAF-FORMATION.

From the Rejuvenescences which the plant experiences
through formation of sprouts, by which the subject (or
theme) of the plant is many times repeated and variously
distributed on the “stock,” in subordinate individual

” The study of sprouts is the broadest and fairest field in Morphology, but
as yet, unfortunately, the least cultivated. What C. Bene long since
accomplished in this department, but has not yet published, I have already
mentioned in a public lecture on “the Vegetable Individual,” which I shall
print after this discourse. The phenomenon ofthe essential and necessary
succession of sprouts long known in the vegetable kingdom, agrees com-
pletely with that occurring in the animal kingdom, the so-called alternation
of generations, brought into its true position chiefly by Sars and Steenstrup.
I have shown this by a detailed comparison in the above-mentioned lecture.

+ Victor Carus has given important hints upon the analogy of the alter-
nation of generations with the succession in the series of organic beings,
in his before-mentioned Essay ‘Zur Naheren Kenntniss des Generations
wechsels,’ p. 54.

5% THE PHENOMENON OF

structures, we pass to the examination of the phenomena
of Rejuvenescence in the individual sprouts themselves.
The single links of Rejuvenescence which we meet
here, are the leaves built up successively one above
another, separated and at the same time held together
by stem-formation, forming, as it were, the persistent
waves of the vegetable life, flowing towards its goal in
alternating rise and fall, concentration and expansion.
But before considering these separate Rejuvenescence-
waves of the sprout, represented in the formation of
leaves, we must examine the greater, upward-striving
periods of the metamorphosis (which contain the smaller
waves within them), as they manifest themselves in the
conditions of the successive leaf-formations.

Previously, however, to tracing the great tide of the
ascending metamorphosis and its subordinate waves, we
will connect this entire section with the preceding, by a
minute examination of certain cases of descending and
vibrating metamorphosis. It has been remarked above,
that not every sprout carries the metamorphosis towards
the goal, that in fact not merely a normal persistence at
particular formations occurs, but in certain sprouts even
a retrogression.* By such a retrogression the sprout
recurs, as it were, to the commencement of its theme,
becoming renovated and rejuvenised in repetition of the
impulse, but giving up as a prey to age the relinquished
product of the earlier period of growth. In fact Rejuve-
nescence of the sprout itself bears great resemblance to
the Rejuvenescence by the formation of new sprouts;
indeed, in a physiological point of view, and in reference
to the vital economy of the plant, these two kinds of
Rejuvenescence are of equivalent import. Both stand
related in the same way to the periodicity of the seasons,
in both cases is seen the same independence of the
new formation of the foregoing structures. As in the
formation of lateral sprouts, the chief sprout from which

* See page 31.

REJUVENESCENCE IN NATURE. 53

they are sent out either dies (Solanum tuberosum, Saxi-
Jraga granulata), or becomes a mere supporting and
subservient scaffold, to a certain extent a soz for the new
generation, so in the Rejuvenescence in the sprout itself,
we again find these two cases, since the fore-running
part of the sprout sometimes dies away, sometimes be-
comes the support of the rejuvenised continuation. The
first case is seen in all root-stocks dying away at the
posterior end,* as also in bulbst dying away externally
and becoming rejuvenised in the centre; the latter we
find especially in woody plants which possess terminal
buds. On the other hand, there is the essential dis-
tinction, in morphological respects, between the two
cases here compared, that in the one case the renovated
vital movement is undertaken by really new individuals
(lateral sprouts), while in the other cases the same indi-
viduals (the old sprouts), rise up to new vital activity,
which distinction has already been remarked upon above,
in the introductory consideration of the buds.{ Moreover
those sprouts which are incapable of advancing to the
uppermost stage, do not in all plants possess the power
of Rejuvenescence through retrogression to a lower stage
of formation, 7. e. the power of forming terminal buds
destined for the succeeding period of vegetation ; this is
rather, indeed, a privilege of but a few perennial herbs
with subterraneous perennial stocks, and of a portion of
the woody plants. Among those which possess this
power, again, two cases have to be distinguished: either

* Anemone nemorosa, Epimedium alpinum.

{ Narcissus, for example. The terrestrial species of /sodies, particularly
I. hystrix and I. Duriei, afford an especially fine instance of this kind. See
my description of them in the ‘Exploration Scientifique d’ Algerie.’

+ Distinction of lateral and terminal buds, pp. 18-20.

Formation of terminal buds does not occur, for instance, on the middle
leal-bearing chief sprout of Urtica urens and Mercurialis annua; since these
plants are ‘also devoid of lateral buds, they die away altogether after the
fruit is quite matured. Urtica dioica and Mercurialis perennis die down
only to the cataphyllary region, from which arise the cataphyllary sprouts
lasting over the winter. Carpinus, Salix, Ulmus, Morus, Maclura, Tilia,
Diospyros, and Calycanthus, are examples of woody plants without terminal
buds.

54 THE PHENOMENON OF

the sprout, after many years’ vibration, runs through, as
it were by a fresh impulse, to the goal, and thus con-
cludes its growth, or it sinks back again to infinity,
after each new flight upward. Both kinds of behaviour
are represented not only among woody plants, but also
among perennial herbs and bulbous plants. In Quercus,
Fagus, Populus, Xylosteum, and Camellia, all the euphyl-
lary sprouts return at the tops to cataphyllary formation,
continuing their growth in the following year from the
terminal bud, with a new euphyllary shoot. ‘They acquire
by this the power of infinite growth, which indeed finally
finds obstacles in old trees, but is made good by taking
off slips and grafts. If we compare with these, Acer,
Esculus, Juglans, Rhododendron, &c., we find the same
condition during a more or less extensive series of years,
but at last, when the growth has elevated the plants
sufficiently above the earth, the shoot is sufficiently in-
vigorated and limited by repeated periodical renovation.
It does not return to the formation of cataphyllary leaves,
but advances to the formation of the inflorescence (with
or without a terminal flower), and then comes to the end
of its growth. In Juglans, only, the female inflorescence
is attained in this manner, while the male catkins appear
as lateral branches. Rhododendron is remarkable, trom
the fact that the terminal shoot of the sprout, which
appears (on branches of full-grown “stocks’’) mostly in
the third year, consequently after two intermissions
(Absätze) with cataphyllary and euphyllary formations,
overleaps the euphyllary formation, and passes at once
from the cataphyllary leaves (bud-scales of the last ter-
minal bud) to hypsophyllary formations, the bracts from
the axils of which the flowers arise. Side by side with
the first-named examples (with infinite rising and sinking
Rejuvenescence), we may place Hepatica, Adora, and
Ozalis Acetosella, from among the perennial herbs. The
Hepatica every spring produces a bud composed of eight
scale-like cataphyllary leaves, followed by three euphyllary
leaves ; after this, it recurs to the formation of a similar

REJUVENESCENCE IN NATURE. 55

terminal bud. The flowers arise laterally from the axils
of the cataphyllary leaves. The Adoza, on the contrary,
creeps along under ground with a slender stem, rising
above the surface every spring to bring forth, after an
indefinite number of small, tooth-like, cataphyllar y leaves,

one to three (mostly two) long- stalked euphyllary leaves,

from the axils of which arise the flowering stems, with
two smaller, sessile, euphyllary leaves, and the head of
flowers. Between the two long- stalked euphyllary leaves
the stem recommences its growth as a descending runner,

repeating the same process in the following spring, and
so on, ad infinitum. Helleborus niger, Anemune nemorosa,
Epimediun, Actea, and Pyrola, may be mentioned as
examples of another kind of growth. I will describe the first
two somewhat minutely, for comparison with Hepatica and
Adoxa; the short ground-stem or root-stock of the black
hellebore annually produces one single euphyllary leaf,
which is succeeded by a terminal bud of two to four cata-
phyllary leaves. After alternating in this way for four
or five years, the euphyllary formation is skipped over,*
or only imperfectly indicated, and the plant attains the
hypsophyllary and floral formations, and then rises up
above the alternating euphyllary and cataphyllary leaf
regions through the elongation of the flowering stem.
In like manner, Anemone nemorosa prolongs its creeping,
subterraneous growth, with alternations of euphyllary and
cataphyllary formations, for several years before it arrives
at flower terminating the shoot. ‘The number of annual
cataphyllary leaves on the horizontal rhizome increases
from year to year, rising gradually to eight, and each of
these preparatory sections terminates with a single long-
stalked euphyllary leaf, till, finally, the last section, after
producing its proper number of cataphyllary leaves, rises
into an upright shaft, producing the three-leaved whor]
of euphyllary leaves and the nodding flower. Among

* As in Rhododendron (sce above) and Pyrola.

56 THE PHENOMENON OF

bulbous plants, the narcissus and its allies, the snowdrop,
on the one hand, the tulip and onion (Allium) on the
other, may furnish examples. Narcissus poeticus, when
arrived at a flowering age, annually produces a sheath-
like, closed, cataphyllary leaf, and four euphyllary leaves,
the last of which, bearing the flower in its axil, is devoid
of the embracing sheath of the preceding. As long as
no axillary flower is produced, the innermost euphyllary
leaf of the annual cycle possesses a sheath. Leucojum
vernum, similar in other respects, has only three euphyl-
lary leaves, the middle one being that which bears the
flower, and is devoid of a sheath; the third, which has
again a sheath, is thus already on the retreat back to
the cataphyllary formation. In Galanthus nivalis the
annual cycle is composed of one cataphyllary leaf and
two euphyllary leaves, the upper of these two being
without the sheath, and with a flower. While in the
heart of the bulb of this plant one annual cycle succeeds
another in an infinite series, the product of the earlier
years dies away, part passu, at the periphery of the bulb,
since not only does one sheath after another dry up and
moulder away, but also the base of the axis of the bulb
throws off the superannuated part by exfoliation. The
old circles of roots are also thrown off, and replaced by
new. ‘The tulip displays a different character. While
in the narcissus the flower arises as a lateral sprout, in
the tulip the heart of the bulb itself shoots up, after
mostly three tubularly closed cataphyllary leaves, into a
flower-stem with euphyllary leaves. But before this
happens, the development alternates for several years
with cataphyllary and euphyllary formations, annually
sending above ground only one euphyllary leaf, and then
returning to cataphyllary formation in the centre. With
this frequently occurs the remarkable case, that, in buds
not yet arrived at sufficient maturity to produce flowers,
the central bud of the bulb sinks down into a descending
spur, formed out of the inclosing base of one of the

REJUVENESCENCE IN NATURE. 57

preceding leaves, in this way leaving the old bulb and
descending deeper into the bosom of the earth.*

A retrogression from the hypsophyllary formation to
the euphyllary, or even to the cataphyllary formation, is
far more rare than the periodical sinking from euphyllary
to cataphyllary formation. Ananas affords a normal and
universally known example of this case, the summit of
the inflorescence returning to the euphyllary formation,
attaining complete Rejuvenescence in the “crown,” as it
is called, and when this is removed and planted producing
new blossom and fruit in the third year. ‘The same phe-
nomenon is exhibited by the New Holland genera of
Myrtaceae, Melaleuca, Callistemon, Beaufortia, and Calo-
thamnus, the brush-like spikes of which owe their strange
“ srowing-through,” or innovation, to a similar recur-
rence to the formation of an euphyllary shoot from the
end of the hypsophyllary region. What are called the
viviparous grasses, e. g. Poa bulbosa and P. alpina, which
occur only in this condition in many places, and behave
like Ananas, might appear as paradoxes, but here it is
really the hypsophyllary region which is made into an
euphyllary region by a retrogression ;+ and the tufts of
euphyllary leaves arising in this way subsequently become
detached, to recommence the ascending development as
independent stocks. At the same time the behaviour of
these grasses is not that natural to the species, but that
of a monstrosity become a variety. Leafy shoots occur
not unfrequently, as a mere accidental monstrosity, at
the summits of inflorescences: I have seen them especially
fine in Plantago lanceolata, where the leafy shoot at the
end of the spike became developed into a new perfect
stock. Even in flowers, retrogression of this kind occurs
as a malformation; well-known garden examples are

* This is not the place for a minute description of this strange phenome-
non. ‘The description of it given by Henry, ‘Nov. Act. Cur.,’ vol. xxi, p. 1,
leaves some questions still open, which I shall take up at another opportunity.

+ The lowest glumes of the spikelets are mostly unaltered here, many of
them even having flowers in their axils. Vide Moll, ‘Bot. Zeit.,’ 1845,
p. 33, t. 1, fig. 2.

58 THE PHENOMENON OF

furnished by the roses, where the stem grows onward
through the middle of the flower, and the Digitalis
purpurea monstrosa,* in which the terminal flower is
grown through in the same way. The female head or
cone of Cycas may be regarded as a flower normally
grown through, with a retrogression from the (certainly
very imperfect) carpel-formation to the cataphyllary and
euphyllary formations. In Cycas, before the age of
blossoming, girdles of scale-like cataphyllary leaves alter-
nate in regular order with girdles of pinnate euphyllary
leaves, which latter at all times form the crown of the
tree. This alternation has, in our botanical gardens at
least, a biennial period, so that the crown of euphyllary
leaves undergoes Rejuvenescence every two years. When
the fruit-bearing age arrives, this alternation becomes
more complicated, the order being as follows: 1, a zone
of cataphyllary leaves (forming before the unfolding of
the succeeding parts a large, shortly conical, terminal
bud); 2, a zone of euphyllary leaves; 3, another zone of
cataphyllary leaves; 4, a zone of spathulate seed-bearing
leaves (carpels), originally packed together in a conical
form, afterwards spread out. In the centre of this head
or cone, representing the female blossom, is formed a new
cataphyllary bud, with which begins anew the whole
cycle of Rejuvenescence, and this is repeated as long as
the tree exists.f

I will not close the examination of these points with-
out remarking, that such periodical Rejuvenescence con-
nected with the alternation of the seasons, is not always
combined with so decided a retrogression of the meta-
morphosis as in the above-mentioned examples. The
retrogression to cataphyllary formation, in particular, is
very frequently absent (but not universally) in the trees
of more southern regions, in which the place of transition
from one yearling shoot to another is merely marked by

* Vide the ‘Flora,’ 1844, No. 1, t. i.
f Vide Rhccde, “Hort. Malabar,’ iii, t. xii, xx, especially t. xvii, where
this growing-through of the female blossom is represented.

REJUVENESCENCE IN NATURE. 59

smaller euphyllary leaves, as for example in numerous
New Holland Myrtacez, as also in the South European
myrtle. While our firs and pines annually retrograde
to cataphyllary budding, we find the limits of the yearling
shoots of the more southern Conifers of the genera Arau-
carta and Cunninghamia, marked merely by smaller
euphyllary leaves. Many evergreen plants, however, of
our own climate, exhibit an exactly similar behaviour, as
for instance, Juniperis communis and Lycopodium anno-
Zinum, in which the yearly lengths are only to be detected
by contracted places on the closely-leaved shoots. Among
herbaceous plants, Lysimachia Nummularia* and Isnardia
palustris belong here, these prolonging their creeping
stem by a considerable piece every new year, while the
lengths of the previous years die away. Veronica Cha-
medrys has the peculiarity herewith, that the euphyllary
shoot, from which the inflorescences go out laterally as
second axial systems, is erect until the time of flowering,
and only bends down its elongating end to the earth
after the plant has flowered, striking root then to ascend
again in the following year and bear flowering branches.t
In Glechoma hederacea, also, the shoots which are erect
until the time of flowering, turn back, at least in part,
towards the ground, not however to ascend again in the
next spring, but to send only branches upward. t

The simplest mode in which the periodical Rejuve-
nescence presents itself to us, is that in which the same
sprout annually produces only one new leaf. Thus in
the brake fern (Pieris aquilina), which annually sends
forth from its subterraneous creeping rhizome only one
of its distichously-arranged leaves, not unfolded until the
third year, an euphyllary leaf, often of enormous size,
and pinnatifid in beautiful gradation up to the fourth
degree. So again in the Ophioglossum, already men-
tioned § above, and at all events in our greenhouses the

* Vide A. de St. Hilaire, ‘Legous de Botanique,’ p. 103.

r Ibid., p. 105.
+ Ibid., p. 105. $ See ante, p. 18,

60 THE PHENOMENON OF

large-leaved Coccoloba pubescens. These cases lead to
the individual leaf, as a link of Rejuvenescence, the in-
vestigation of which, however, must be preceded by the
consideration of one point more.

The rejuvenising force and activity of vegetable life
does not display itself merely in the particular cases of
periodical, retrogressive, or alternately advancing and
receding metamorphoses, such as we have just examined ;
it shows itself also in the ascending metamorphosis, in the
advancing series of formations, such as occur as the
universal types in the higher divisions of the vegetable
kingdom. Here occurs, in the closest connection with
the progress from stage to stage, an alternation of
vigorous advance and checking retraction, an increase, a
decrease, and a renewed rise of the energy of the outward
representation, a Rejuvenescence in the truest sense of
the word, since here with every new onward flight of the
old being, the plant appears notin mere repetition of the
old form, but by deeply grounded renovation, in a more
perfect and more expressive shape. ‘This it is which,
since Goethe’s time,* has been called the metamorphosis
of plants, a term borrowed from the transformation of
insects, which has however given rise to mistaken views,+
but is capable of being made the basis of a more pro-
found cenception of the phenomenon. Goethe himself,
although his theory of metamorphosis is mixed up with
various obscure elements, pointed out many features of
the more profound side of the question. He speaks of
the metamorphosis of plants not merely as of a series of
outward phenomena of transitions between the different
structures, but as of an inward principle of the formative
process advancing from one modification of form to
another. In his eyes the metamorphosis was a force which
might be observed ever acting with a graduated power

* «Versuch die Metamorphose der Pflanze zu erklären,’ Gotha; 1790.

‚7 That Goethe was not even free from the erroneous notion that one organ
of a plaut might be actually transformed into another, e. g. stamens into

petals, or ovaries into leaves, is evident from the very first paragraph of his
Introduction.

REJUVENESCENCE IN NATURE, 61

from the first seed-leaves to the final maturation of the
fruit, and, by the conversion of one form into another,
leading up to the highest point of vegetable life, as it
were, by an ideal flight of steps.* This ideal flight of
steps which Goethe perceived in the metamorphosis of
plants, is a speaking testimony of the profound con-
ception of it entertained by him; for that which leads
the formative process of the plant from one stage to
another, which connects the steps of the series, which
causes each succeeding step, although separated from the
preceding, to appear as a stage of conversion of the
latter, can in reality be only an inner and ideal bond.
Only the inner identity of the nature of the plant,
through all the change of outward manifestations, can
justify us in regarding the gradually advancing Rejuve-
nescences as really a metamorphosis, that is, a series of
transformations of an essentially identical element. In
this sense Goethe speaks, too, of the mysterious affinity
of the different external organs of plants, pointing out
that the real identity of the organs corresponding to each
other at the different stages can indeed only be deduced
from that inward connection of the steps of the meta-
morphosis, and not from mere outward resemblance.
Goethe already directed attention to the great vibra-
tions of the metamorphosis which we here first examine,
since he speaks of an alternation of expansion and con-
traction in the successive leaf-formations.F This is one
of the most important factors in his attempt to explain
the metamorphosis of plants; for a minute discussion of
which, however, it is necessary that we should cast a
hasty glance over the series of the leaf-formations them-

* Vide Goethe, 1. c. § 6.

+ Goethe, l.c. “From the seed up to the highest development of the
stem-leaf, we observed first an expansion, after which we saw the calyx arise
from a contraction, the petals from an expansion, the reproductive organs by
another contraction, and shall now soon make out the greatest expansion in
the fruit and the greatest contraction in the seed. In these six steps
Nature completes, without pausing, the eternal work of the propagation of
vegetables.”

62 THE PHENOMENON OF

selves. The metamorphosis of plants exhibits three
principal divisions: 1, the “ stock,” or as it is termed in
plants not forming wood, the herd (kraut) ; 2, the flower;
3, the fruit. The first two divisions are again divisible
each into three stages, while the third principal division
does not admit of further analysis. ‘Thus we obtain
from 3+3+1 the number 7 for the stages of form in
plants. The character of these seven sections or regions
is chiefly expressed in the graduated change of shape of
the leaf, while the stem takes a less striking, though still
considerable share in the transformation from step to
step. We shall therefore consider the steps of the
metamorphosis more particularly in regard to the
behaviour of the leaf, as it presents itself at the different
heights upon the plant, applying to the more essential
gradations which are distinguishable the denominations
of so many leaf-formations. Asa general rule, as already
stated, there are seven of these, which, however, do not
exhibit perfect representatives in every plant, for their
number may be lessened either by imperfect differentia-
tion, or by falling short of or overleaping forms.

1. The cataphyllary formation (Meder-blatter), to
which belong the scales and sheathing leaves of subterra-
neous or aérial buds, bulbs, runners, and tuberous rhi-
zomes. ‘They are remarkable from their broad basis,
small height, and most simple shape and nervation ;* they
have no lamin, no stalks, no subdivision,t consequently
never have stipules, and are constantly entire. ‘Their
consistence is often fleshy, cartilaginous or leathery, in

* In dicotyledonous plants even these are mostly parallel-nerved, and the
parallel-nerved appearance of the euphyllary leaves of the monocotyledons is
but a sign that the euphyllary leaf-formation is less characteristically deve-
loped in them, and hence is more like the cataphyllary formation than is the
case in the dicotyledons.

{ There are exceptions to this in the cataphyllary-leaves separating into
two distinct scales, in the buds of certain trees, e. 7., Betula, Carpinus, Corylus,
Fagus, and Quercus. This structure may be regarded as a transition towards
the euphyllary-leaf formation, the leaf being here divided into two stipules
and an abortive central leaf. In Quercus the first bud-scales are still

undivided. These conditions are described by Doll,—‘ Zur Erklärung der
Laubknospen der Amentacen,’ 1848.

REJUVENESCENCE IN NATURE. 63

rare instances they are delicately membranous, in which
cases the axis which bears them is mostly fleshy ; their
colour is nevera decided green, generally whitish, passing
into yellow, flesh-colour, brownish, or even black. Their
development goes on very slowly; they are tolerably en-
during, and the chief part of their existence is passed in
the winter season.

2. Euphyllary formation (Laub-blatter).—These are
the organs, especially and ordinarily simply called “leaves,”
which give most character to the vegetative structure or
stock. They are readily distinguished from the leaves of
the preceding formation by the greater longitudinal
development with a narrower base, in general more con-
siderable dimensions, and the green colour, never absent
although in many cases concealed. Their especial mark
is the blade-structure, with which is ordinarily combined
its contrary, the stalk or petiole structure. Through
multifold alternations of the conditions of expansion and
contraction arises the so frequent production of divided
and compound euphyllary-leaves, to which also belongs,
as a special case, the division into main-leaf and accessory
leaves (stipules). The multiplicity of conditions of ner-
vation within the body of the blade, corresponds to the
multiformity in the outline of the leaf. The consistence
is mostly stoutly membranous, frequently leathery, more
rarely fleshy. The principal part of the life is passed in
the summer ; the duration is considerable, especially in
those of fleshy or leathery consistence.

3. Hypsophyllary formation (Hoch-blätter), to which
belong the involucral leaves and common calyces of inflo-
rescences, bracts and bracteoles, glumes and paleze, which
accompany the flower. These again approach in charac-
ter the cataphyllary leaves, as the stalk and blade-struc-
tures, as well as the green colour, vanish more or less or
even quite completely.* They are distinguished from

* Stalked hypsophyllary-leaves are a rarity, e. g., in Podolepis; the
formation of astalk occurs more frequently above the sheath-like part of the
leaf, as for instance, in the formation of awns on the glumes of the grasses.

64 THE PHENOMENON OF

the cataphyllary-leaves chiefly by the narrowness of the
base, more delicate structure, and more rapid formation
and decay.

4. Formation of the calicine-leaves (sepals). These
form the first proper envelope of the flower, and are
again thicker, tougher, and greener than the upper-leaves,
mostly have a broader base, little or no laminar expansion,
no stalk-formation, and are either simple or but slightly
divided.* ‘They are mostly more euduring than the
succeeding formations of the flower, they often outlive
these, and frequently take part in the formation of the
fruit.

5. Formation of the corolline-leaves (petals), strikingly
characterised by delicacy of texture, beauty and variety
of colour, with the exclusion, however, of green. As a
rule, they are longer than the sepals, but have a
narrower base; mostly exhibit an extensive laminar por-
tion but no distinct stalk-structure, often radiant or
forked, but very rarely pinnate, division. Excrescent
growths doubling the limb or laminar structure (emer-
gences) sometimes occur upon the surface of the petal,
as in Narcissus, Nerium, Lychnis, or longitudinal wing-
hike edges, as in Saponaria, Agrostemma, and the Hydro-
phyllacez.

6. Formation of the pollen-leaves (stamens), com-
prising the smallest and thickest leaves of the flower,
characterised by distinct stalk-formation (filament) from
the narrowest base, with a box-like expansion of the
lateral halves of the little developed blade (anther).
Folding over of the blade (Uederspreitung), which occurs
but rarely in the petals, is here almost an universal rule,
whereby the chambers of the anther become doubled on
each side. They are distinguished above all the other
parts of the flower by the most rapid completion of the

* Sepals with pinne (Rosa), with stipules (Peyanum), or with a ligule-
structure (Mesembryanthemum), are rare exceptions.

r Ex. gr. Schizopetalum. Drummondia.

REJUVENESCENCE IN NATURE. 65

structure, and the greatest perishability after the opening
of the blossom.

7. Formation of the Fruit-leaves (carpels). These are
again larger, thicker, greener than preceding parts,
but especially distinguished by the permanent folding
together, passing into confluence. Springing from a
narrow base, the lower part expands like a blade, forming
the cavity of the fruit by closing together its own borders
or coalescing with the neighbouring carpels, while the
upper part is mostly drawn out (stalk-like) into the style.
From the inside of these leaves arise the little seed-sprouts
(ovules), so that they become the cases of the seeds,
running through with these a process of development
(maturation), prolonged far beyond the life-time of the
flower, and often requiring even more than one year for
its completion.*

To those who have studied Comparative Morphology
in an unprejudiced manner, there can be no debate on
the question as to whether all the structures of these
seven formations are really leaves. On this side the theory
of metamorphosis stands on a firm and unshakeable
foundation.t But the structure which is to be erected
on this foundation, the theory of the formations, giving
the true representation of the vital history of the plant as
it is displayed in the successive transformation of similar
fundamental organs, is as yet unfortunately scarcely dimly
shadowed forth. It is a problem which appears so much
the more difficult the nearer we try to approach to its
solution, for it then is not sufficient to mark the characters

* The ripening of the fruit and seeds occupies two seasons in many Conifers
(Juniperus communis, Pinus,) and many oaks (Quercus Cerris, Suber, rubra, &e.)

+ Wigand (‘Kritik und Geschichte der Lehre von der Metamorphose der
Pflanzen,’ 1846, p. 118,) very correctly calls “the great law of the unity of
all axial and of foliar organs,” the nucleus of the doctrine of metamorphosis,
remaining behind when we have subtracted the multifold and strange cloth-
ing with which it is ordinarily enveloped. On the other hand, the problem
of giving to the discovered nucleus its true natural investments, does not
appear to be sufficiently recognised. Multiplicity will not be wanting in the
true clothing, and we shall certainly have to own to strangeness and oddity
in nature. 5

66 THE PHENOMENON OF

of the formations by comparison of external forms, which,
from the multiformity prevailing in the vegetable kingdom,
is an endless task ; for the true characteristic of the forma-
tions must be at the same time an inward one: it must
comprehend the outward product in its relation to the
inner vital tendencies, entering into conflict with the
external world,—and thereby endeavour to represent to
us the developmental history of vegetable life according
to the inner causes leading through all the external com-
plications. ‘That the above short description of the leaf-
formations can make no claim to such a character as this,
need not be said; it is merely intended to bring forward
a few peculiarities calculated to make evident the regular
alternation of rise and fall in the course of metamorphosis,
its successive “accessions” or “flights” (4ufschwiinge),
which we desire to examine here as phenomena of Reju-
venescence. The peculiarities which we have chiefly to
keep in view here are,—the relative size of the leaf in
general; then, in particular, the breadth of the base in
proportion to the circumference of the stem; the height
or length of the leaf; the development in breadth above
the base (the lamination), and its opposite, the contraction
into stalk-formation, on the contrasted proportions of
which chiefly depend the further working out of the
forms of leaves; finally, the solidity or delicacy, and the
persistence or caducity. Even the most superficial ex-
amination reveals clearly that the path through the
formations from “ stock” to flower, and again from flower
to fruit, does not ascend uniformly, that it does not
exhibit either an uniform decrease in the perfection of
the organs, or an uniformly increasing refinement of their
structure. The assumption of a single rise and fall in
the perfecting of the leaf-formations, the highest point of
which should fall in the middle (the euphyllary formation),
is equally opposed to experience, for even the flower, and
still more the fruit, contradicts this view.* It is, indeed,

* Agardh goes so far on this false hypothesis, as to regard the higher

REJUVENESCENCE IN NATURE. 67

unmistakeable that the leaf-formations take three succes-
sive onward flights (Aufschwünge) in the course of the
metamorphosis: one in the stock or body of the plant,
one in the flower, and, finally, the last in the fruit. A
close investigation of this phenomenon shows, that there
are also subordinate risings and sinkings even within the
first and second regions of elevation.

If we examine, in the first place, in reference to this
point, the conditions of breadth of the base of the leaf,
we find on the stock or stem of the plant, from the first
to the last of its leaves, a decrease, sometimes gradual
and sometimes taking place by starts, and this decrease
is indeed so constant, that perhaps every exception might
be traced to the phenomenon of retrogressive metamor-
phosis examined above, although it is not equally obvious
in all.* But with the advent of the flower a new increase
of the breadth of the base of the leaf frequently occurs,
the sepals exhibiting a broader base than the highest

development of the fruit consequent on fertilisation as a pathological con-
dition, a disease. (!) ‘Essai de réduire la Physiologie végétale & des
principes fondamentaux,’ 1828, pp. 32, 38.)

* Among these exceptions is the condition of the cotyledons in the
numerous dicotyledonous plants in which the opposite half-embracing
cotyledons or seed-leaves are succeeded by alternate, more extensively em-
bracing euphyllary-leaves, or wholly or almost wholly embracing cataphyllary-
leaves, which latter is the case, for instance, in Aseram. In the mono-
cotyledons, on the contrary, the seed-leaf is always completely amplexicaul.
There appears, moreover, a strange case in Convallaria majalis, in which a
number of cataphyllary-leaves forming closed sheaths, are followed by one
which is only two thirds embracing, (the same which bears the inflorescence
in its axil), and this is succeeded iy two euphyllary-leaves, which are again
completely amplexicaul. Crocus luteus, also, and other species of this genus,
exhibit a strange aberrant condition to be mentioned in connection with the
foregoing. A number of completely embracing cataphyllary-leaves, closed
round into tubes, are succeeded i euphyllary-leaves, mostly arranged
according to the % position, the sheath-like basilar portions of which are
not closed into tubes, but are confluent together one with another in the
direction of the longitudinal path of the line of arrangement of the leaves,
(the spiral line cutting through the points of origin of the successive leaves),
whence arises as it were a single connected spiral sheath common to all the
euphyllary-leaves. The breadth of the base of a single leaf consequently
amounts here to % of the circumference of the stem. ‘These are followed
by hypsophyllary leaves preceding the terminal flower, the first closed into
a tube, like the cataphyllary-leaves, the second, on the contrary, open,
and only imperfectly embracing the stem.

68 THE PHENOMENON OF

hypsophyllary-leaves. This may be observed especially
in calices with right-handed overlapping reaching down
as far as the base. That the breadth of this decreases
again in the region of the petals and stamens, might even
be deduced from the fact, that scarcely any right-handed
(eutopic) overlapping occur, since the overlappings do
not proceed from the base, but only arise from the over-
lapping of the petals subsequently expanding above. The
stamens, as a general rule, never overlap, and the great
number of them which stand in a circle in many poly-
androus flowers, shows the narrowness of their bases.
The bases of the carpels are not expanded transversely or
overlapping, it is true, but their smaller number, in the
majority of cases, as well as their close approximation,
nevertheless testifies to the greater thickness of their
bases. The decreasing breadth of the base in the leaf-
formations of the “stock” may be made clearer by the
mention of a few more examples.

Tulipa.—The bulb exhibits 3—4, completely embracing,
tubularly closed, cataphyllary leaves, followed by 3—4
euphyllary leaves on the stalk which shoots up, the
lowest of the latter being still amplexicaul and closed
round at the bottom, the succeeding embracing in a
gradually decreasing extent 3 to }.

Convallaria Polygonatum.—The cataphyllary leaves on
the horizontal rhizome completely embracing, the margins
even overlapping. The first of the euphyllary leaves
occurring on the stem rising above ground embraces
almost completely, about &ths; the second 3 or 3; all the
following 4.

Veratrum (nigrum).—The subterraneous cataphyllary
leaves, which are best seen in autumn on the still unde-
veloped central buds of young “stocks,” or in the lateral
buds of older “stocks,” are embracing, and form a cone
or cup, closed completely, with the exception of a small,
scarcely perceptible slit at the upper end, this cap being
broken through above in the subsequent unfolding of the
bud. The first six or seven euphyllary leaves have long

REJUVENESCENCE IN NATURE. 69

closed sheaths, reaching down to the abbreviated sub-
terraneous portion of the stem ; these are followed mostly
by two sheaths, also closed round, but shorter, which
arise on the portion of the stem shooting up. The suc-
ceeding euphyllary leaves, further separated from each
other, and becoming progressively narrower and shorter,
are no longer embracing, and exhibit a gradual decrease
of the breadth of the base, following something like the
ratio 3, %,4,2,1,1,2,!, and then remaining more equal,
decreasing to } as a minimum. ‘The leaf embracing }
is the first which produces a branch, the lowest lateral
spike of the large, compoundly spicate inflorescence
arising on its axil. The small hypsophyllary leaves,
from the axils of which the individual flowers arise, em-
brace 3 or}.

Valeriana officinalis. —The subterrancous runners ex-
hibit white, one-sidely apiculate, completely embracing,
cataphyllary- leaves, closed into tubes by the blending of
their borders. Of the alternating, two-ranked euphyllary-
leaves succeeding them, the lowest have likewise a com-
pletely embracing sheathing base, while the last embrace
only about 3. The euphyllary- leaves found on the erect
part of the ‘stem are connected in pairs, and embrace ;
or, on the triple whorls sometimes occurring, only }. The
hypsophyllary leaves have an arrangement similar to that
of the euphyllary leaves, but the two opposite leaves of
each pair do not quite reach one another with their bases ;
they are less than }, finally only } embracing.

Heraclewm.—The lower and middle euphyllary leaves
of the species of this genus have overlapping sheaths,
therefore they reach somewhat more than completely
round the stem; the upper, already smaller ones, having
a less divided and scarcely stalked lamina, usually approxi-
mated together, and having the umbel-bearing branches
in their axils, exhibit imperfectly embracing sheaths,
rapidly decreasing in breadth, about in the proportion
3 4 3, 4, or falling still more quickly. Finally, the small
linear, or almost bristle-like hypsophyllary leaves of the

70 THE PHENOMENON OF

involucre and involucel exhibit scarcely 4 — + breadth of
the base.

Mahonia Aquifolium.—The cataphyllary leaves (bud-
scales) are about 2 embracing; the euphyllary leaves
falling to 3 or}; the hypsophyllary leaves on the axis of
the panicle }; the little bracteoles (vorblätter) occurring
on the stalk of the flower itself, which, however, rarely
come to evident development, are still narrower than the
bracts (deck-blätter) of the inflorescence.

Thus the plant, as a general rule, exhibits the phe-
nomenon of decrease in regard to the breadth of the base
of the leaf, yet with two retrogressions (inconsiderable,
however), namely, at the commencement of the flower, and
again at the close of series, in the formation of the fruit.
The following remarks wil] show that this decrease in the
breadth of the base of the leaf does not in itself indicate
any decrease in the energy of the leaf-formation, but that,
on the contrary, the expansion of the base stands in an
antagonistic relation to the development of the middle of
the leaf.

The development of the leaf in length or height, which
is the most influential factor in reference to the size of
the leaf generally, and the vigour which declares itself in
its formation, exhibits, in the progressive metamorphosis
of the plant, a totally different course from that of the
breadth of the base. Both in the first and second regions,
on the “stock” and in the flower, the longitudinal deve-
lopment of the leaf shows, first an increase and then a
decrease; the commencement of the last region, the
fruit, is connected with another increase. Thus after a
double rise and fall the terminal formation is attained in
a third ascent. Reviewing first of all the first region,
we find that the first cataphyllary-leaves of a sprout are
always the shortest and smallest; this rule prevails, in
like manner, in the first euphyllary-leaves of plants, or in
individual sprouts of plants where the cataphyllary leaf-
formation is wanting. The cotyledonary commencement
often forms an exception in this respect, as in reference

REJUVENESCENCE IN NATURE, 71

to the conditions of breadth, for the cotyledons of many
plants are longer and larger than the succeeding leaves
of the principal sprout, as, for example, in Quercus,
Vicia, Casuarina, Opuntia, &c. The increasing length
in the succession of cataphyllary-leaves, may be seen in
beautiful gradation almost everywhere on the subter-
raneous buds of perennial herbs, and on the buds of
trees; see, for instance, Peonia, where the 6 — 7 lower
leaves show graduated increase from 3 lines to 1! inch,*
Mahonia Aguifolium, where they increase from 1 to 6
lines, sculus,t Rosa,t Rhododendron,§ &c. The
increasing length and magnitude of stem-leaves in
germinating plants is especially well seen in Acer,
Corylus, Vitis, Phaseolus, &c. The increasing length of
the leaves is mostly continued, more distinctly in the
euphyllary than in the cataphyllary formation, till it
reaches its maximum in a determinate median region,
from which an equally graduated decrease commences,
mostly prolonged even into the hypsophyllary region.
It depends on the conditions of extension of the stem
whether the maximum of the longitudinal development of
the euphyllary leaves lies in the lower abbreviated part
of the stem, so that all the euphyllary leaves situated on
the developed internodes belong to the decreasing series ;
or, when no such rosette-like crowding of the lower
euphyllary leaves exists, at a determinate height on the
shoot itself.| Examples of the first kind are seen in
Nigritella angustifolia, Chrysanthemum Leucanthemum,

* Decandolle, ‘Organographie,’ t. xxi, figs. 1, 3.

+ Ibid., t. 20.

+ Malpighi, ‘ Anat. Plant., t. xii, fig. 59.

§ Henry, ‘ Knospenbilder,’ Nova. Acta. Nat. Cur., xxii, 1, t. xxii.

|| Both conditions are found combined, consequently a double maximum
in the euphyllary formation, a lower in the abbreviated part of the stem (ina
rosette of what are termed radica] leaves), and an upper, on the shoot,
mostly, it is true, distributed through two seasons, in many biennial plants,
e. g., Pedicularis palustris, Anarrhinum bellidifolium, Ginothera muricata, as
also in perennials with biennial sprouts, e. g., Jasione perennis and Pulmonaria
officinalis, This phenomenon, however, does not properly belong here, but
to the case mentioned above at page 59 of retrogressive metamorphosis
within the euphyllary formation.

72 THE PHENOMENON OF

Hieracium vulgatum, Scabiosa Columbaria, Swertia peren-
nis, Aconitum Lycoctonum, &c.; examples of the second
in Orchis globosa and maculata, Canna, Hieracium
subaudum, Gentiana germanica, Bocconia cordata, Aco-
nitum Napellus, Helleborus fetidus, and Ruta graveolens.
Under these circumstances, when the number of leaves is
great, the increase and decrease are often very gradual,
as for instance, in most species of Linaria, Linum,
Phiox, &c. Thus in Phlox paniculata, where the sprout
begins with pairs of half-embracing subterraneous cata-
phyllary leaves, 1 — 3 lines long, and rounded off at the
top, we see above ground about thirty pairs of broadly
lanceolate, acuminated euphyllary leaves, which are only
about $ embracing, and attain their greatest length, of
about 3 inches, somewhere near half-way up the stem,
from which point they decrease, at first almost imper-
ceptibly, more rapidly in the inflorescence, and finally
pass into the hypsophyllary formation. The last finely-
pointed hypsophyllary leaves are only about 3 lines long
and scarcely } embracing. In other cases the leaf-
formation ascends to its maximum by a few large steps,
sinking down again as quickly, as for instance, in Hydro-
phyllum canadense. This plant bears upon its condensed
lower-stem (rhizome) which creeps on the surface of the
ground, distichously arranged, thick, fleshy, persistent,
cataphyllary scales from } to } an inch long; the last two
scales of the sprout* usually pass at their points into a
petiole- and blade-formation, and therefore are already
the first euphyllary leaves, distinguished however from
the following by their persistent fleshy scale-base. These
first two euphyllary leaves are already developed in
autumn before the sprout shoots up; the first is often
only rudimentary, the second longer and stronger, at-
taining a height of 3 to 6 inches. These are followed

* That is to say, in case it has sufficient force to blossom. Young plants,
and the weaker lateral shoots of older ones, alternate for a year
between euphyllary and cataphyllary formation, like the examples men-
tioned at pp. 54-55.

REJUVENESCENCE IN NATURE. 73

mostly by three more euphyllary leaves (unfolded in the next
spring), the first of which is seated either on the creeping
portion of the stem, or raised but a little above the
ground on the lowest part of the erect euphyllary-leaved
stem, and it is by far the largest of all, for it equals or
even exceeds in height the entire shoot, attaining a length
of a foot to a foot and a half. The two following,
situated high up on the stem, are, the first 9 to 6 inches,
the second 4 to 3 inches long. The hypsophyllary leaves
succeeding upon the inflorescence are totally suppressed
in this plant. ‘The exaltation of the leaf-formation ex-
pressed in the euphyllary formation appears most strikingly
in the cases where this is represented by a single euphyl-
lary leaf, which is then mostly of remarkably large size.
Thus in Zpimedium alpinum,* where the tolerably numer-
ous subterraneous cataphyllary leaves, from 1 to 5 lines
long, are ordinarily followed by a single twice or thrice
divided euphyllary leaf about a foot long, after which the
metamorphosis springs over suddenly to the small and
numerous hypsophyllary leaves, the length of which
amounts at most to 1 line, and sinks to!d ofaline. There
is somewhat of a deviation from the usual position of the
maximum of development in length of the leaves, in the
rare cases where this occurs at the end or the beginning
of the euphyllary formation, instead of in the middle.
We see the first case in Heliconia cannoidea,t in which
the decrease of length commences in the hypsophyllary
formation ; the last in Paonia and Actea. The bane-berry
(Actea spicata) presents on the subterraneous stock several
short-sheathed cataphyllary leaves, increasing in length
from 1 to 3 lines; to these succeed, upon the erect stem,
mostly three euphyllary leaves; the lowest, largest, very
decomposed, is about 1 foot long, while the third,

* Other examples of one-leaved euphyllary formation are furnished by
Malazis monophylla, and very many exotic Orchidacee; also by many
Aroidee, e. g., drum echinutum, (Wall. pl. as. rar. t. cxxxvi) ; by Gesneriacee,
as in Platystemma violoides, (Wall. 1. c., t. cli); by Sanguinaria; and lastly
by many Cyperacex, as for example, Scirpus mucronatus.

f Richard, ‘Comment. de Musac.,’ t. ix.

14 THE PHENOMENON OF

uppermost and smallest, mostly only simply trifid, is
from 1 to 2 inches long. The hyposophyllary leaves,
following the last, and from whose axils arise the flowers
of the terminal spike, are from 1} to 1 line long.

In conclusion, I will describe the phenomenon of in-
crease and decrease in the length and size of the leaves
upon the “stocks” of plants, in one more example,
where it presents itself in an uncommon grandeur, namely,
in the plantain (A/usa).* I have not had an opportunity
to examine the subterraneous portion of the stem of this
plant, rismg upward from a horizontal commencement ;
when this comes above ground, as a young shoot, we at
first see a few cataphyllary leaves, which are probably
preceded by a considerable number underground. In
M. sapientum they are acuminated, triangular, shining,
dark-brown leaf-sheaths, which manifest the commence-
ment of the euphyllary formation by the commencement
of petiole- and blade-formation at the summits. Not
only the sheath but also the stalk and lamina now grow
longer, from leaf to leaf, until the well-known splendour
and magnitude of the plantain leaf are attained. The
complete development of the sprout of a plantain re-
quires with us several years, in its tropical home at most
two years; the outer leaves die away as the inner unfold.
All the leaves of a shoot which has not yet shot forth
into blossom, arise close to the ground on an abbreviated
stem, and, simply by the rolling of their sheaths round
one another, form a tall pseudo-stem, whence Richard
called Musa a bulbous plant. Consequently the length
of the leaves here determines the height of the entire

* The following statements are derived from two species in the botanic
garden of this town (Freiburg), one large, with overhanging inflorescence
and numerous flowers in the axils of bracts, which appears to be Musa
sapientum, and a smaller, with erect inflorescence and beautiful rosy bracts
with only three flowers in each axil. In our garden this bears the name of
M. rubra. On this especially have I been able to investigate minutely the
distribution of the leaves upon the stem in reference to height. The
arrangement of the middle-leaves is # in both, of the bracts 4. In the
statements of the conditions of length of the two species I shall distinguish
thein as M. sapientum and M. rubra.

REJUVENESCENCE IN NATURE. 75

plant. Under these circumstances the innermost leaves
are the longest; in M. sapientum I have found them as
much as 25 feet long, of which the sheath made about
13 feet, the petiole 2 feet, and the blade 10 feet. In
M. rubra they are only about 15 feet long, the petiole
being longer in proportion than in AZ. sapientum. From
the point where the stem shoots up into the slender
flower-shaft, breaking through the stem-like convolution
of sheaths, commences the decrease of length of the
leaves. In M. rubra I found as many as five euphyllary
leaves on the elongated portion of the stem, the upper
three of which, especially, exhibited a considerable de-
crease, not merely in the length of the sheath, but also in
that of the blade; the last of them was only about 4 feet
long, namely, the sheath 13, the stalk 1, and the blade
13 feet. The internodes bearing these last five euphyl-
lary leaves measured respectively about }4, 1, 2, 3, 3 feet
in length. Not quite 2 feet distant from the point of
origin of the last euphyllary leaf, followed a transitional
leaf, about 13 feet long, and of broadly-linear, gradually
acuminated form, leading to the hypsophyllary formation;
at no more than 2 inches above this, began the long
succession of approximated, ovate, rosy bracts, the first
of which are about 5 inches long, the following sinking
down gradually to 3—2 inches. The lowest six bracts
of the inflorescence of M. rubra which I examined, bore
female flowers in the axils, all the succeeding bore male
flowers.* Musa also exhibits a beautiful graduation of
the breadth of the base of the leaves. All the leaves of
the lower part, up to the flowering-shoot, are completely
embracing. I found, in M. rubra, the uppermost three
euphyllary leaves embracing 4%, 18, and $ of the circum-
ference; the transitional leaf 2, the bracts of the female
flowers } to 2, those of the male }. In the plantain,
therefore, we see the leaf-formation ascend by gradual

* According to Rumph, in Musa paradisiaca 12 to 20 bracts have female
flowers, and 12 to 20 of them in each axil; so that a single inflorescence
bears 100 to 200 fruits.

76 THE PIIENOMENON OF

stages, from a few inches often to the enormous length
of 25 feet, and sink down again, with more rapid steps,
to about the same brevity; to which it must be added,
that on minute examination of the earliest subterraneous
leaves of the sprout, and of the cotyledons of the germi-
nating plant, the point of departure would doubtless be
found smaller, as, on the other hand, we may conclude,
from the file-like rows in which the flowers stand in the
axil of a bract, that the (in proportion to the flower) large
bracts are not the last members of the hypsophyllary
formation, but that undistinguishable hypsophyllary-
leaves (bracteoles) exist at the base of the individual
flowers, forming the true termination of the leaf-forma-
tion of the “ stock.”

A similar rise and fall in the length of the leaves is
repeated in the region of the flower. ‘The sepals are
sometimes immediately connected with the last hypso-
phyllary-leaves by their length, often by their whole
form, excepting the usually greater breadth; this is the
case in Helleborus fetidus, Ruta graveolens, and Phlox
paniculata, in which the sepals agree alınost perfectly, in
size and shape, with the last hypsophyllary-leaves. But
more frequently the calyx exhibits a new increase of
length in relation to the last hypsophyllary-leaves. To
confirm this I need only refer to the numerous plants
which possess bracteoles (Vorblätter) on the peduncles of
lateral flowers, these bracteoles being almost always very
small and slender, and even frequently almost indis-
tinguishably small; see, for instance, Aconitum, Del-
phinium, Viola, Polygala, Colutea and other Legumi-
nose, Molucella, Calamintha, Gratiola, Convolvulus, &e.
We can also detect this in terminal flowers, e. g. ın
Dianthus, where the sepals, blended below into a long
tube, are preceded by several pairs of shorter scales ;*

* The two to three pairs of scale-like leaves beneath the calyx of the
pinks increase in Jength in the ascending order, and therefore belong pro-
perly to the new advance of the leaf-formation commencing in the flower,
forming an epicalyx, as occurs also in the mallow.

REJUVENESCENCE IN NATURE. 717

also in Hypericum calycinum, in which the sepals of the
solitary terminal flowers are twice or four times as long,
and three to four times as broad as the preceding hyp-
sophyllary-leaves ; finally, most distinctly in Chelidonium
majus, in which the sepals are about three lines long,
while the two to three pairs of preceding hypsophyllary-
leaves, from the axils of which the lateral flowers of the
corymb arise, attain scarcely half a line. In the calyx
itself the metamorphosis usually keeps at the same stage,
so that at least no remarkable difference occurs among
the sepals ; yet the cases are not rare in which an evident
gradation occurs within the calyx itself, an increase of
length corresponding to the succession of the sepals ; as,
for instance, in the quinate calyx of Hypericum caly-
cinum, imbricated in the 2 arrangement, the inner two
sepals of which are almost twice as long as the outer
two, the third being of intermediate length. The con-
ditions are similar in Polygala, where the innermost two
sepals are not merely many times longer than the outer
three, but already exhibit the petaloid colour, forming
what are called the wings of the flower.* In Ozyria
and the female flowers of Urtica we find a four-leaved
calyx, the outer two sepals of which are shorter than the
inner two; in Rumex a six-leaved, with three outer
shorter, and three inner longer. Berberis has a double
ternate, Mahonia and Podophyllum a triple ternate, and
Epimedium, a triple binate calyx; in all these the inner
whorls are formed of longer sepals than the outer.
Lastly, in the Cactez, as also in Calycanthus, the gradual
increase of length is exhibited most remarkably with an
acyclic structure of the calyx.

The length of the leaf within the flower attains its
maximum in the corol/a. It is scarcely necessary to illus-
trate, by examples, the proportionate lengths of the
corolla and calyx; and the assertion that the petals are
longer than the sepals in the majority of plants possessing

* The same occurs in Diplerocarpus.

78 THE PHENOMENON OF

corollas, will not be contested although we omit to
demonstrate it by a numerical comparison, which of
course would have to be based on a determinate and
perfectly known flora. Splendid and conspicuous exam-
ples of it are furnished by the genera Datura (e. g.
D. arborea), Convolvulus, Gentiana (e.g. G. acuulis),
Campanula, Cucurbita, Paonia, Dillenia, Hibiscus, &e.
This relation holds good also in small-flowered plants, as,
for instance, in Vitis, in the Umbelliferee and the Com-
posite. Even in the Monocotyledons, where generally
speaking the abrupt differentiation of calyx and corolla
does not exist, the inner three segments of the perianth
are frequently distinctly longer that the outer three, as,
for instance, in Lachenalia and Uropetalum, of the Lily
family, in all the Bromeliaceze, Commelynez, Cannacez,
and Alismacee. The rarer occurrence of petals shorter
than the calyx, is explained, in many cases, by an intro-
version of one formation into the other, whereby the
maximum of longitudinal development becomes displaced.
Thus, in many Ranunculacee (e. g. Trollius, Nigella) the
petaloid calyx is succeeded by shorter and more contracted
petals approximating to the stamens. In other families
also occur isolated genera, with a petaloid calyx, the
leaves of which are longer than the true petals; e. g. in
Fuchsia (calyx mostly bright-red, rarely white, petals
mostly violet), Aedes (Chrysobotrya), Commarum, and
Chimonanthus. The last-named genus has about eight
delicate yellow sepals, followed by an equal number of
dark purple-red petals, only half as long. In other cases
the small size of the petals is connected with a tendency,
prevailing in many families, to suppression of the corolla
(Sibbaldia, Sagine sp., Paronychia, Gnidia, Santalun,
&c.), to which we shall return hereafter.

No farther increase of length takes place within the
corolla itself, at least I am unacquainted with any instances
of it; on the other hand, the decrease which succeeds to
the maximum of longitudinal development in the second
member of the flower, not unfrequently commences even

REJUVENESCENCE IN NATURE. 79

within the formation of the corolla. Thus in most cases
of double or multiple corollas we see the inner circles
formed of shorter and smaller petals. In Fumaria the
inner two petals are only inconsiderably, but in Hype-
coum considerably shorter than the outer two. Jacguinia
and Achras exhibit the same thing in pentamerous and
hexamerous circles. Asimina triloba has a trimerous
calyx, the sepals of which are four lines long. This is
followed by three trimerous circles of petals : those of the
first circle are 7—8 lines long, those of the second about
5 lines, and those of the third scarcely more than 2
lines long. The stamens are 1 line long; the three-lobed
fruit (formed of three carpels) attains a length of 4—5
inches when ripe! The decrease of length of the inner
petals is further shown in all flowers with very numerous
petals, whether they stand in a complex cyclic or in an
acyclic arrangement, as, for instance, in Zllicium, Nym-
phea,* and Mesembryanthemum.t Finally, the graduated
decrease in length in successive petals is very beautifully
exhibited by all “double” flowers, as they are called, and
most distinctly of all, in those where the doubling arises
merely from formation of petals in the place of stamens (and
often of carpels also), without the superaddition of axil-
lary sprouts.{ ‘The best examples of this kind are found
in the Ranunculaceze, especially in Ranunculus, Clematis,

* Nymphaea alba has about twenty-four petals, the inmost and shortest of
which exhibit a gradual transition into the staminal formation.

+ Many species have more than one hundred petals.

+ In the majority of double flowers the “doubling” is complicated by the
formation of sprouts in the axils of the petals. The sprouts thus appearing
are again imperfect flowers, with undeveloped axes, and mostly formed of
few petals and occasionally several stamens. Hence arises an apparently
irregular accumulation of large and small petals, interposed in various direc-
tions, and often intermixed, with isolated stamens, of which it cannot be
accurately determined which organs belong to the parent flower and which
to the progeny. This occurs frequently, for instance, in double May
flowers, Pinks, Cruciferz, Mallows, and Roses. However, doubling some-
times occurs with and without axillary increase in the same plant. Some-
times the axillary products of double flowers acquire greater completeness,
as is shown most beautifully in the case not unfrequently occurring in
gardens of Althea rosea, first observed by G. Engelmann, Vide Engelmann,
‘De Antholysi,’ t. i, fig. 6.

80 THE PHENOMENON OF

Hepatica, Caltha, and Aguilegia. The Camelliee, the
Campanulaceze and Narcisse@ also exhibit this kind of
“doubling,” and the decreasing length of the petals
connected with it.

With the transition from corolla to stamen-formation
commences a new decrease in length. Far the majority
of plants possessing a highly developed corolla, agree in
having the stamens, notwithstanding their considerable de-
velopment of stalk, shorter than the petals. Cases of the
opposite kind, in which the stamens exceed the corolla in
length, are rather rare.* Where two or more successive
circles of stamens exist, there is often a further degrada-
tion in length, the inner stamens being shorter than the
outer. This is the case in Warcissus, Muscari, Daphne,
Myricaria, Boronia and other Rutacex, many Mal-
pighiacee and Melastomaceee, Zythrum, Crategus, &c.
An opposite relation of length in successive circles of
stamens does however occur, to which we shall return in
the subsequent examination of the subordinate rises and
falls of the metamorphosis.

The third and last increase in length presents itself in
the fruit, often expressed even at the flowering epoch, by
the projection of the points of the carpels (styles and
stigmas) beyond the stamens, as universally in the
Campanulacez, Composit, and Cactacez, but often first
becoming distinct with the ripening of the fruit.}

Thus the leaf-formations exhibit altogether three maxima
in reference to length and magnitude, the first falling in
the euphyllary formation, the second in the corolla, the
third in the fructification. These maxima become some-
what displaced if we regard the leaf in reference to its
inner differentiation, to the more or less distinct develop-
ment of the contrast between stalk- and blade-formation,
and the completeness of the working out of form con-

* For example: Ribes stamineum, Fuchsia, Cynoglossum stamineum, Hydro-

phyllum magellunieum, Hyssopus,Vaccinium stamineum, Erica stamineu, carnea,

multiflora, &c- j F
+ Leguminose, Crucifere, (especially the SiZiquos), Geraniacca, Palme,

&e. See also Asimina triloba, above, page 79.

REJUVENESCENCE IN NATURE. 8

nected therewith. In the first region, indeed, the
euphyllary formation exhibits the maximum in this
respect also; in the flower, on the contrary, it is not the
corolline but the staminal formation which represents the
maximum in relation to internal subdivision, since we
detect in the latter the most distinct separation of
petiolar and laminar formations. Even vaginal and
stipuloid expansions and appendages now and then occur
at the base of the stamens, still further confirming the
analogy with the euphyllary formation. The same
position also denotes the physiological importance of
the staminal leaves; for euphyllary leaves, staminal
leaves, and carpellary leaves, are evidently the three most
essential leaf-formations, to which the most important
physiological functions are distributed, and without which
a perfect and complete plant is inconceivable,* while
there is a possibility of all the rest being omitted. At
the same time I have hitherto searched in vain through
the Vegetable kingdom for a plant devoid of all the
inessential formations at once, possessing, that is, really
only leaf, stamen, and fructification.

The maxima of the leaf-formation are again differently
distributed when we take the consistence and persistence
of the leaves for a standard. In the first region the
euphyllary leaves claim the highest place in this respect
also, for although succulent and fleshy cataphyllary leaves
are not rare, the majority of them are soon killed by the
growing warmth of spring, while the euphyllary leaves of
very many plants, fleshily succulent as well as leathery,
are of several years’ duration.t In the flower, the
calyx has the greatest durability, thereby showing a
relation on the one hand to the euphyllary formation,

* Only such plants as do not elaborate their own nutriment, parasites on
living plants and parasite-like vegetables which are nourished like Fungi on
decaying remains, can dispense with the leaf-formation.

T Ze. gr. in the Cycadex, Conifere, Palme, Aloe, and Ayave, Crassu-
lacex, Arzoidee, Buxus, Ilex, Citrus, Laurus, and the endless host of ever-
green trees of the tropical zones. In the silver fir the duration of the
acicular leaves extends to seven or eight years.

6

82 THE PHENOMENON OF

and on the other to the fruit, which relationship is also
particularly confirmed by many abnormal phenomena.
In monstrous affections of the flower, namely, the calyx
on the one side passes very readily into a leafy structure,
and, on the other, often acquires a fruit-like develop-
ment, not only normally, but also in abnormal ways,*
while in return the fruit may become calicoid, or even
strike into leafy structure in antholytic flowers. In the
point of view just examined, therefore, the euphyllary
formation, calyx, and fruit, form the analogous sections
of the three regions.

The preceding indications may suffice to show that
the leaf-formation by no means exhibits merely a simple
decrease or increase, but, in all respects, a swaying up
and down, a series of vibrations, in the last of which
only is the goal actually attained. These vibrations are
not of equal magnitude or equal force in all plants; on
the contrary, there occurs, without affecting the general
law, a great multiformity in their conditions. Some-
times the wave expressed in the vigour of the leaf-
formation, rises and sinks slowly and gradually, as we
have seen in the vegetative region of Pilox; sometimes
it gathers itself up abruptly and suddenly, asin Apimedium
and Mayanthemum; sometimes it ascends suddenly and
sinks down more gradually, as in Peonia; sometimes it
ascends contrariwise, gradually, and sinks down again
more suddenly, as in Hel/iconia. "Ihe transition from
one region of ascent to another is marked sometimes by
a slight, sometimes by a strong depression. ‘This differ.
ence is especially manifested in the transition into the
flower, since on the one hand there is not unfrequently a
direct passage from the euphyllary formation into calicine
formation, (almost devoid of any retrogression in the
leaf-formation, and with total omission of the hypso-
phyllary formation especially representing the descending

* I have observed this in especial beauty in a malformation of Citrus
medica, where the calyx formed as it were an open citron surrounding the
inner natural fruit. :

RUJUVENESCENCE IN NATURE. 83

side of the first region,) as in Gentiana;* while, on the
other hand, the leaf-formation often sinks down before
the transition into flower, to complete disappearance of
the leaf, which as it were emerges anew in the
flower. Within the general lines of rise and fall, even,
occur other subordinate lines of undulation, correspond-
ing to the individual formations, which will be briefly
touched upon hereafter. Every plant has its proper vital
lines for these vibrations of the metamorphosis, the
constructive representation of which lines will make
clearly conceivable, characters which botanists have
hitherto only seized in the most fragmentary manner, or
have felt obscurely as something indescribable in the habit.

A particularly important phenomenon belonging to
this series is the occurrence, at determinate points of
transition of the metamorphosis, of the above-mentioned
disappearance or non-appearance of leaves which exist in
rudiment, but either do not come to full development, or
are suppressed in the earliest stages of formation.t This
dipping down of the leaf-formation, occurring so frequently,
and connected with determinate regions,t is the best evi-
dence of the undulating course of the metamorphosis, and
the best criterion for the separate sections. Disappearance
of this kind occurs at four different places in the process
of the metamorphosis, namely, first at the two points of
depression, already considered above, at the points of
transition of the three chief regions one into another,
from stock to flower and from flower to fruit ; and at two

* See especially G. campestris, in which the first two sepals are com-
pletely foliaceous,

T This phenomenon belongs to what botanists call adortus, against the
multifold groundless and superficial assumptions of which Schleiden very
justly inveighs repeatedly, (‘ Grundzüge,’ ii, 188.) The correct application
of the comparative method will guard us from such idle speculation, and
indicate to us with certainty suppression of leaf-formation, even in cases
where observation of the course of development is perhaps never capable
of affording a demonstration.

+ Another series of abortions, here left entirely out of view, is connected
with the zygomorphic and antagonistic structure of what are called irregular
flowers.

84 THE PHENOMENON OF

other, subordinate points of descent which have still to
be examined more narrowly, at the transition of the
euphyllary formation unto the hypsophyllary formation
and of the corolla (or calyx) into the staminal formation.
In order to represent the occurrence of regions of vanishing
in their relation to the entire graduated series, we will
once more review the series, in the order of the tran-
sition of the metamorphosis from formation to formation.

Within the cataphyllary formation we have observed
an increase of strength in the leaf-formation, which is
continued without any preparatory decrease into the
euphyllary formation. The leaf-formation runs progres-
sively from the cataphyllary formation to the euphyllary
formation either without any, or with imperceptible descent
at the point of transition, consequently no vanishing ever
occurs between these two formations. I shall not venture
to decide whether this transition takes place really without
any descent, or sometimes, perhaps, has connected with
it a slight decrease in the leaf-formation. The latter
hypothesis seems to be borne out by Adonis vernalis. I
found the 7 or 8 cataphyllary leaves of this plant of
gradually increasing length, growing from 1 to 8 lines; a
transitionary leaf following them, and exhibiting the first
trace of blade-structure at its apex, was somewhat. shorter
than the last true cataphyllary leaf, namely, only about 7
lines long.

In the euphyllary formation we see the attainment of
the maximum of vegetative leaf-formation followed by a
decrease, which is frequently continued into the hypso-
phyllary formation without any new accession of strength.
But the case is not always such; the transition of the
euphyllary formation into the hypsophyllary formation is
often effected through the medium of a strongish retro-
gression, which may go as far as disappearance, whereby
then the hypsophyllary formation is cut off as a distinct
wave, since it then possesses its own special rise and fall.
The hypsophyllary region, cut off in this way, thus forms
within the vegetative sphere a prototype of the flower,

REJUVENESCENCE IN NATURE. 85

which affords a certain justification of the old application
of the name “compound flower,” to the capitule of the
Composite and the spikelet of the Grasses. If we examine
the order of capitulous-flowered plants (Composites) in
reference to this point, we find hypsophyllary forma-
tion but seldom exhibiting a mere decreasing condition
of the leaf-formation, for the involucres or “common
calices’’ are mostly formed of hypsophyllary leaves larger
than those immediately preceding them on the stalk,*
and within the involucre itself there mostly occurs a
further increase of size of the successive involucral-leaves,
as is shown in the so-familiar “involucra calyculata”
and ‘imbricata.”+ This phenomenon is truly splendidly
exhibited in the coloured, radiantly expanded involucres
of Carlina, Xeranthemum, and Helichrysum. In the
last-named genus (e.g. in H. proliferum), we even find
the rare case of hypsophyllary formation far exceeding in
its ascent the size of the euphyllary leaves. After the
maximum is attained the hypsophyllary formation sinks
down again, upon the main axis, to the form of little
palez or teeth, often passing into a fibrous dissolution,
frequently at last vanishing altogether, (receptaculum
paleaceum, denticulatum, fibrillosum, nudum.) I will
describe somewhat minutely in this respect Calhopsis
bicolor, an ornamental plant generally diffused in gardens,
as an example. Cataphyllary leaves are absent. We find
the leaf-formation advancing, on the abbreviated base of
the stock, from simple to simply pinnatifid and bipinna-
tifid euphyllary leaves. On the ascending part of the
stem follows a decreasing series of small-lobed bipinna-
tifid, simply pinnatifid, and at last simple euphyllary
leaves, which form the transition to a few very small
linear, brownish-coloured hypsophyllary leaves scattered
on the stalk of the capitule. The 8 outer leaves of the
involucre are already somewhat larger, especially broader,

* See, for instance, Hieracium subaudum and allied species, Leontodon
squamosus, Catananche caerulea.
+ Ex. gr. Chrysanthemum Leucanthenum, Taraxacum, Scorzonera, Cynara.

86 {HE PHENOMENON OF

than the preceding scattered hypsophyllary leaves; the
8 inner involucral leaves, in the axils of which are seated
the 8 florets of the ray, are 5—6 times as long and broad
as the outer, lighter coloured, and more scarious. This
constitutes the maximum of the hypsophyllary formation;
the succeeding bracts (paleze) are shorter, almost filiform,
and transparent, with a thin brown central streak. Another
example, which exhibits not only a sinking and reascent,
but an actual disappearance, at the transition from the
euphyllary to the hypsophyllary formation, is afforded by
Emilia sagittata (Cacalia sonchifolia of gardens.) The
large euphyllary leaves embracing the stem with their
arrow- or heart-shaped bases, are followed by a narrow
linear transitional leaf, from the axil of which arises the
first branch of the corymbose inflorescence. From 2 to 4
leaves are thus wholly suppressed, their existence being
merely detected by the branches of inflorescence being
apparently devoid of subtending leaves. ‘The leaf-
formation rises up again in the involucre of the ter-
minal capitule, composed of 13 equally long, linear
hypsophyllary leaves, and generally vanishes again on
the “receptaculum nudum.” A similar disappearance
and re-advance of the hypsophyllary formation, only
distributed on distinct axes, 1s seen in those Umbelliferze
which are devoid of an involucre, but have an involucel,
as for instance in Angelica sylvestris, Seseli montanum
and Hippomarathrum, and Bupleurum rotundifolium.
The leaves of the involucels are at the same time the
bracts (subtending leaves) of the outermost flowers of the
umbellule, while the subsequent, more internally situated
flowers, arise from the axils of suppressed leaves. Thus,
the Bupleurum mentioned has only five involucellar
leaves, but eight to thirteen flowers in each umbellule,
the central flower not included; therefore three to eight
flowers must spring from the axils of invisible leaves. A
third large order, in which the hypsophyllary formation
occurs in similar conditions, is that of the Grasses. Here
it is universal for the euphyllary formation to be followed

REJUVENESCENCE IN NATURE. 87

immediately by a suppression of the leaf-formation, which
persists through the whole main superstructure of the
inflorescence, and only ceases in the spikelets. The leaves
often disappear entirely in this region, or they present
themselves as more or less evident thickenings, some-
times completely embracing the stem as rings,* and then
often curved up and down in wavy lines, sometimes only
partially embracing, and then mostly with decurrent
borders,+ rarely ascending on the axis.{ In Zlymus
europeus the lowest annular abortive leaf is often elon-
gated into a sharp tooth; in Nardus all the subtending
leaves of the spikelets are tooth-like. Only few grasses
exhibit a considerable development of the lower leaves on
the axis of the inflorescence, such as occurs in Ses/eria.
In Sesleria cerulea they present themselves as tubular,
ochraceously-truncated, or irregularly excised, mem-
branous sheaths.§ A similar development of the first
leaf of the inflorescence occurs not unfrequently as an
accident and exceptionally, in other grasses. I have
observed a strange form of this phenomenon, and this
frequently, in Glyceria aquatica. The transitional leaf
occurring here, in the axil of which stands the first so-
called semi-verticil of the panicle, has an undeveloped

* Thus, for instance, the lowest abortive leaf of Zritieum, Secale, Oryza,
&c., while the succeeding do not embrace; in Glyceria fluitans and aquatica
several of the lower abortive leaves are annular.

T Especially fine in Melica altissima and Phalaris arundinacea. Very
beautifully so in the lower abortive leaves of Lolium, Pou compressa,
Cynosurus, and Dactylis. The obliquely descending borders are even con-
fluent on the lowermost. The overlooking of these abortive leaves led to
the error of regarding the glume of the spikelet of Lolium as its subtending
leaf. This mistake might be pardoned in a superficial examination, but it is
incomprehensible how any one could see the true condition clearly, and even
draw it, and yet retain the false explanation, as Turpin has done. See his
plate of Lolium perenne in the ‘Dict. des Sc. Nat.,’ and the explanation
given of the figures.

{ Thus, for example, the lowest and not always distinguishable abortive
leat of Alopecurus agrestis.

§ These ochraceous leaves are followed by one or the other unilaterally
developed bract; at the base of the uppermost lateral spikelet, on the
contrary, they vanish entirely, as in other grasses. In Oreochloa they are
not so strongly developed, and only the lowest are one-sided. See on this
point also Roper, ‘Zur Flora Meklenburgs,’ ii, 42.

Ss

I

THE PHENOMENON OF

middle, simply a protuberance, while the lateral portions
growing together on the side opposite to the middle,
acquire very considerable development. Hence arıses an
appearance as though the subtending leaf stood opposite
tothe branch. It often attains a considerable size and a
more or less foliaceous expansion, exhibiting a distinction
into stalk and blade. 'The sheath usually reaches a length
of 1! to 2 inches; the blade seated upon this, about of
equal length, is double, on account of the absence of the
middle, the two halves diverging at an obtuse angle.
Among the grasses in which the disappearance of the
leaves in the inflorescence is most complete, so that even
the lowermost often does not even leave a protuberant
process, are Catapodium, many species of Hragrostis,
Eleusine, Digitaria, and Sorghum. In the spikelets,
finally, the leaf-formation comes to light again, frequently
gradually, as in Oryza,* and all other grasses in which
the first glume is very small (Vadpia, Avrochloa, Anthox-
anthum) ; frequently suddenly, as in all grasses with two
large glumes (Holeus, Phalaris). Most of the many-
flowered grasses exhibit, further, a distinct increase and
falling off in the successive hypsophyllary leaves of the
spikelet, since the first sterile paleae are shorter than the
succeeding fertile ones, which themselves again decrease
in size towards the point of the spikelet.F It is rarer for
the first palece to be the largest, so that a simply decreasing
condition exists.} The reverse, a merely ascending con-
dition of the paleze of the spikelet, is exhibited by many
one-flowered grasses, in particular the already cited Rice,
and most of the genera allied to Panicum.§

* In Oryza the spikelet begins with four sterile palex, followed by only
one fertile. The first two or three sterile palex appear only as small teeth.
Leersia is distinguished from Oryza merely through the still more imperfect
development of the first four pales of the spikelet.

+ Thus, for instance, in Bromus, Festuca, Pou, Dactylis, Secale, Melica,
Molinia, Phragmites, Chloris.

{ ‘Thus in 7riodia, Agrostis, Calamagrostis.

§ A deercasc may take place in these in an abuormal manner, when,
namely, the axis or rachis of the spikelet develops additional pales (and
flowers in their axils). An inteicstivg case of this kind occurs almost

REJUVENESCENCE IN NATURE. 89

From the vanishing region at the entrance of the
hypsophyllary formation, where this separates as inde-
pendent, we come to the consideration of that transition
in which the disappearance of the leaf-formation is com-
monest, to the transition from the hypsophyllary formation
to the flower. Here where the most important revolution
occurs in the metamorphosis, where the leaf-formation is
to return in new arrangement and altered attire, there is
most frequently a preparatory total contraction, so that
the region of transition into the flower must be desig-
nated as the principal break in the metamorphosis. The
disappearance of the leaf-formation occurring here may
extend simply to a last organ, or over the entire hypso-
phyllary formation ; in fact, it may even invade the outer
formations of the flower. Of the first case, in which only
a final section of the hypsophyllary formation undergoes
suppression, we have already seen above a fine example
in the Composite with naked receptacles succeeding a
fully-developed involucre; and in the Umbellifere with
umbellules, the outer rays of which arise in the axils of
involucellar leaves, while the inner possess no visible
bracts. Such cases are more uncommon on racemose or
spicate inflorescences with elongated axes, but Castanea
and Acalypha may be mentioned, the spikes of which
have perfectly developed hypsophyllary leaves at the lower
part, bearing the female flowers in their axils, while the
male flowers succeeding upward arise from the axils of
abortive leaves. Here refer also the Aroidez, which
possess a large, often petaloid, coloured hypsophyllary
leaf at the base of the spadix, while no further visibly
developed leaves occur upon the spadix. Suppression of
the last hypsophyllary leaves is more commonly found
when these are situated on a second axial system, than

normally in a Panicum cultivated in gardens, which I have named P. (Eehino-
chloa) mirabile. This species, allied to P. stagninum, very frequently presents,
besides the three ordinary glumes and the normal palea (een enclos-
ing the flower, a second smaller palea, which, like the first, conceals a
perfect flower in its axil.

90 THE PHENOMENON OF

when on the same axis. Thus it is a very common
phenomenon for the axis of racemose inflorescences to
have developed hypsophyllary leaves (bracts), while those
on the flower-stalks (vorblätter, bracteoles) are suppressed.
Numerous examples of this are furnished by the Scrophu-
larinex,* Verbenacez,t Labiate,+ Leguminose,} and
also Fumaria and Corydalis, Hedera Helix, Mahonia,
Thesium ebracteatum and rostratum.|| The other case,
in which the entire hypsophyllary formation is composed
of abortive leaves, is likewise very common, we find it in
almost the whole family of Crucifere, in Convallaria
multiflora, of which, besides, there is a variety with de-
veloped and even foliaceous bracts ; in many Leguminose,
e.g. Trifolium, in the Umbelliferze without involucre and
involucel, e. y. Anethum and Feniculum. Great numbers of
examples might be cited of plants with terminal flowers,
where consequently the leaf-formation reappears again on
the same axis, in the flower, after the suppression of
several leaves, e.g. Solanum, Gilia tricolor, capitata, many

* Ex. gr. Digitalis, Antirrhinum, mauy species of Linariu, Verbascum
Blattaria, while in Verbuscum Thapsus, aud the allied species, as also in
Serophularia, Gratiola, &c., the bracteoles are developed.

t Ferbena, Aloysia, while Vitex exhibits developed bracteoles.

£ Teuerium, Prunella; in many other genera of the family the bracteoles
are visible. Sewtellaria exhibits a beautiful transition to the suppression of
the bracteoles, for in many species, for instance S. alpina, they exist only
as scarcely perceptible papille. Sadvia presents a series very instructive in
this respect. S. patens and dulcis have solitary flowers standing in the
axils of bracts, without visible hracteoles; S. coccinea, splendens, and involu-
crata, have three-flowered, S. farinosa (trichostyla, Bischoff), and confertiflora
many-flowered cymes without visible bracteoles ; S. Horminum three-flowered
cymes with developed bracteoles of the middle flowers, but not of the
lateral flowers ; ‚$. glutinosa, lastly, has three-flowered cymes with developed
bracteoles of both the middle flowers and the lateral flowers.

§ Pisum, Galega, Podalyria australis; in Colutea and Lupinus the extremely
small bracteoles at the base of the calyx are often scarcely visible; in other
genera, Phaseolus in particular, they are more considerably developed.

|| I have purposely chosen only such examples as at once show the exist-
ence of the supposed bracteoles, either by the visible presence of these in
other genera of the same family, or even other species of the same genus,
leaving out of the question other grounds for the assumption. In the
family of the Fumariacez they are visible in Déelytra; in the Berberidee in
Berberis itself; in the genus Hedera in H. capitata; in the genus Thesium in
all the other indigenous species except the two mentioned above.

REJUVENESCENCE IN NATURE. 91

Boraginese (Myosotis, Omphalodes linifolia), most of the
Hydrophyllez (Phacelia, Hydrophyllum canadense), Cistus
salviefolius and monspeliensis, Ulmaria palustris, &e.

The suppression of the leaf-formation at the transition
into the flower may affect, as above remarked, not merely
the last section of the leaves preceding the flower, but
even the commencing formations of the flower itself. Thus
we see the calyx, at least its free portion, undeveloped or
appearing as a crown of hairs in the Composite, many
Umbellifer&, Rubiaceze, and Valerianez, while the corolla
is developed fully in these families. Calyx and corolla
are suppressed together in Fraxinus, while the nearly
related genus Ornus exhibits both; the same occurs in
many Amentacee, especially of the group of Betulacese.*
The perigone of the Monocotyledons is suppressed in
many Aroidee, e.g. in Calla, while it is visible in Pothos
and Acorus ; in the Cyperaceze, also, where it frequently
presents itself in the form of bristles, which may be com-
pared to the pappus in the Compositze ;f and, finally, in
the Grasses, in which, however, the inner circle of the
perigone, analogous to the corolla, comes to light, wholly
or partly, in the form of little scales (/odicule).t

* In Alnus and Betula the calyx is indistinguishable in the female flower,
but visible in the male; in Carpinus and Corylus, on the other hand, the male
flower is devoid of a visible calyx while the female possesses one.

+ The three scales in the flower of Fuirena do not belong to the perigone,
but correspond, as Nees correctly assumes, to the inner circle of stamens.
They stand decidedly inside and not outside the three fully-developed stamens.
See, for other points, the in other respects accurate description of the flower
of the Fuirene, by Schlechtendal, (‘ Bot. Zeit.,’ 1845, p. 849.)

+ The inner perigonial circle is perfect, composed of three little scales, in
Stipa and the Bumbusee; in most of the other grasses it is imperfect, the
leaf falling posteriorly being suppressed. Sometimes the abortion extends to
the inner circle of the perigone, as in Crypsis, Alopecurus. As regards the
foundation for the assumption of an outer, constantly abortive perigonial
circle, it can only be observed here that it is derived from the comparative
study of the rudiments of the branches of the monocotyledons and the rules
of insertion of lateral flowers dependent thereon. Under the hypothesis
that it possesses a double perigone, the flower of the Grasses stands in the
axil ofits bract exactly like the bracteolate flower of the Iridex. The same
attachment of the flower is probably to be assumed of the Cyperacez also,
only in this family the bracteole (the inner palea) is constantly suppressed,

while in the Grasses it is fully developed, except in a few cases (Trichodium,
Alopecurus).

92 THE PHENOMENON OF

We now come to the transitions within the flower
itself. The transition from the calya to the corolla cor-
responds to that from the cataphyllary to the euphyllary
formation, and takes place like thıs, without any, or with
an insignificant retrogression of the leaf-formation, on
which account no suppression occurs between these two
formations. We have above seen, in many cases, an
increase of the leaf-formation within the calyx, and re-
cognised in this the expression of the renewed impulse
received in the first half of the flower; the contrary case,
a decrease of size following the order of succession of the
sepals, expressing an indentation in the line of impulse
ascending to the corolla, is a rare phenomenon, and is
only represented by faint mdications. Thus in the
Gentiane, Gerania, Nicotiana, even in the Roses and
Brambles, the mner sepals are somewhat shorter than the
outer. Of all cases of this kind, the calyx of Acanthus
exhibits the most striking character, which, however,
from the irregularity of the whole flower, cannot be
explained simply in this way. It is composed of four
pieces, an upper, broadest and longest (the second sepal);
a lower, somewhat narrower and “shorter, which has two
points (it is formed from the confluence of the first and
third sepals); finally, two lateral, which stand further
inwards, and are much shorter than the upper and lower
pieces.* These little lateral sepals are the fourth and
fifth, consequently the last two leaves of the calyx. The
calyx is preceded by two very narrow linear bracteoles,
which are about half as long as the calyx; a broader and
longer bract, having sharply-toothed borders, bears the
flower in its axil. Here, therefore, we see a descent from
the bract to the bracteoles, an ascent from the two
bracteoles to the outer sepals, and another descent from
these to the two inner, and finally, from these to the
corolla a fresh ascent of the leaf-formation.

That which is found only in rare and faint indications

* The two lateral picces are 13 to 2 lines long, the lower about 15 lines,
the upper 17 lines.

REJUVENESCENCE IN NATURE. 93

in the transition from calyx to corolla, is a very frequent
phenomenon in the transition from the corolla to the
stamen-formation. As the hypsophyllary formation is
not unfrequently cut off from the euphyllary region by
sinking down even to the suppression of the leaf-forma-
tion, so we see the stamen-formation frequently cut off
similarly by a region of suppression, from the preceding
formation. It is often difficult to decide here whether
the parts subject to abortion, which may occupy one or
more circles, are to be regarded as suppressed inner
petals or suppressed stamens. As imperfectly developed
leaves, they are, looked at by themselves, neither one nor
the other; but comparative examination shows that the
abortive circles are certainly to be attributed sometimes
to one and sometimes to the other side, and in this sense
are to be regarded sometimes as inner circles of the
corolla, and sometimes as outer circles of stamens. Thus
in the Primulaceze for example, we have reason to con-
sider the abortive circle as an inner corolline circle, since
the corresponding circle of the flower is developed in
some of the genera of the allied family of the Myrsinez
(e.g., Jacquinia), as also in many of the genera of the
likewise related Sapotez, actually in the form of an
inner corolla, never in the form of a circle of stamens.
The same holds of the Ericacex, in which I have seen
the abortive circle developed abnormally, in Zrica
baccans, as an inner corolla. ‘The same occurs in the
Jasminez, for some of the species of jasmine exhibit
an inner corolla almost normally. In the Oxalidez and
Geraniaceze we must also assume an abortive inner
corolla, the traces of which exist in the form of glands or
little scales. In abnormal flowers of Pelargonium, I have
often found some of the organs actually developed into
the form of petals. That the abortive circle of the
Geraniacez is to be regarded as an inner corolla, is still
more distinctly proved by the mode of arrangement of
the parts of the flower in the genus Monsonia, belonging
to this order. Monsonia possesses not merely two, but

94 THE PHENOMENON OF

three quinate circles of stamens, which though 5 prosen-
thesis are placed in a ternary relation of alternation, while
the abortive circle still belongs to the binary condition of
alternation (though } prosenthesis). In the Crassulaceze
likewise, the abortive circle may be regarded as an inner
corolla, although the arguments for this are less direct.
On the contrary, the abortive circle is in some cases
decidedly an outer circle of stamens, for instance, among
the Monocotyledons, in the Burmanniaceee and Ponte-
deracex, among the Dicotyledons, in many Malvaceze
and Tiliacez, e.g., Helicteres, Hermannia, moreover in
the Ampelidee and Rhamnex. Both united, 7. e.,
two abortive circles, a suppressed inner corolla and a
suppressed outer circle of stamens, at the same time,
occur in the Crassulacee which have only one circle of
stamens properly developed, as for instance Crassula
and Zillea ; likewise in Brodium, of the family of the
Geraniacex, and the allied Zinum; in Bleria and
Azalea, of the heath family.* As we have seen in the
conditions of the transition to the flower, examined above,
that the whole of the preceding hypsophyllary formation
frequently vanishes, so this is repeated here. Not
merely particular segments, but even the entire corolla
may vanish. We have already seen an approximation to
this in the exceptional cases, in which the maximum of
the leaf-formation within the flower is not attained in
the corolla, but already in the calyx, while the petals
appear small and imperfect.+ The apetalous flowers
produced in this way occur in very many families,? and
allow their true nature to be readily decided when we

* In this and similar cases no circle seems to be absent, since when two
succeeding circles are suppressed, the alternation of the properly developed
circle is restored.

T See pages 78, 79.

{ To prevent misunderstandings, I must remark that the condition of
abortion is not the explanation of all apetalous flowers. There are families
in which the metamorphosis actually progresses directly from the calyx-
formation to the stamen-formation, without any suppressed intermediate
formation corresponding to the corolla; thus, for instance, in the Polygonez
and Laurinex.

REJUVENESCENCE IN NATURE. 95

accurately make out the conditions of relationship. Thus,
for example, the genus Glaux agrees so closely with the
type of the very sharply-defined Primulacez, that we
have no hesitation in ascribing the apetalous condition of
this genus to the suppression of two circles of petals.
The Chenopodiaceze, Amarantacez, and Scleranthez, are
connected so unmistakeably with the petaliferous families
of the order of the Caryophyllacez, particularly with the
Alsınee, that we at once regard them as Apetale pro-
duced by the suppression of the corolla, especially when
we take into consideration how such a suppression occurs
in particular cases among the Silenee and Alsinee, and
may even be demonstrated in one and the same species,
sometimes in all gradations, as for instance, in Stellaria
media, which is found with very different sizes of the
petals down to complete abortion of them (var. apetala).
The conditions are similar in the apetalous state of
Peplis among the Lythrariee, Isnardia among the
Onagrex, Chrysosplenium among the Saxifragee, Sterculia
among the Tiliaceze, and Pistacia among the Terebin-
thacee. In Phytolacca decandra, the quinate corolla
vanishes together with a ten-membered outer circle of
stamens, which latter exists perfectly developed in PA.
icosandra.

I will only add, to these already too widely extended
remarks on the subordinate retrogression of the leaf-
formation which is frequently interposed at the tran-
sition to the stamen-formation, and which causes an
independent separation and uplifting of this most im-
portant section of the flower, that the ascending condition
in the succession of stamens or of circles of stamens,
mentioned above as an apparent exception,* is explained
by this, corresponding exactly to the rise in the magni-
tude of the hypsophyllary leaves, which we have already
examined. This phenomenon is met with, for example,
in Aloe, Anthericum, Ornithogalum, in which the three

* See page 80. T See page 85.

96 THE PHENOMENON OF

inner stamens are longer than the three outer, also in
the Crucifere, in the well-known tetradynamous con-
dition ; in Asarum, with six outer shorter, and six inner
longer stamens; in Rhewm, with six outer shorter, and
three inner longer ; in Oxalis and Limnanthes, with five
outer shorter, and five inner longer; in Monsonia, with
ten outer shorter, and five inner longer; lastly, most
beautifully in Zibiscus and other Malvacez, in which
numerous quinate circles of stamens are piled up into a
more or less abundantly clothed column. Most of the
Ranunculacee, in particular Anemone decidedly, exhibit
a gradual increase of length of the stamens, together
with an acyclical, spiral arrangement of them ; and many
of them a decrease again at the close of the formation,
as in Peonia Montan, the innermost, shortened, and
abortive staminal leaves of which, form by their con-
fluence the well-known crimson crown round the germen,
which Decandolle considered as one of the principal
supports of his theory of the torus.*

The structure of the chinese Peony just noticed, leads
us to the examination of the transition from the stamen-
formation to the fruit, the last chasm which the plant
has to pass over in its path to the goal. In this transition
to the last stage of the metamorphosis, a complete sup-
pression of the leaf-formation occurs far more frequently
than at the transition from the corolla to the stamen-
formation, a circumstance of especial importance for a
correct insight into the structure of most flowers. In the
Monocotyledons only, in which in general the formations
are less sharply separated, a direct transition, uninter-
rupted by intermediate abortive circles, is the more
frequent condition, while in the Dicotyledons this occurs
as the rule only in few families, particularly such as
exhibit affinity to the Monocotyledons in other respects ;
in many others not at all, or only in isolated genera.
This also furnishes the explanation of the rarity of

* Decandolle, ‘ Organographie,’ i, 184.

REJUVENESCENCE IN NATURE. OF

abnormal transitions between these two formations, a
transformation * of stamens into carpels, or, retrogres-
sively, of carpels into stamens,t while the transitions
between calyx and corolla, as well as between petal- and
stamen-formation are comparatively far more frequent.
The abortive circles must here be accounted partly to
one and partly to the other of the formations adjoining,
the altered conditions of arrangement and number so
frequently occurring in the fruit affording a distinct sup-
port for this in many cases. The abortion of an inner
circle of stamens is exhibited most convincingly by many
species of Juncus, which occur sometimes hexandrous and

* T use this term in the sense explained above, pp. 60, 61.

+ The occurrence of such transitions is in most cases a certain indication
that no abortive circle exists, but the cases must be closely examined, in
order that a mere multiplication of the organs of one or other formation,
such as may happen through an alteration of relative position or through
axillary formations, may not be taken for a substitutive aberration of
structure. Consulting the sections on the transformation of pistils into
stamens, (218), and stamens into pistils, (220), in Moquin Tandons
‘Teratologie,’ we find that after separating the doubtful from the trust-
worthy and accurately known cases, the examples mentioned belong to
three families of the Monocotyledons, (the Liliacew, Colchicacee, and Palme),
and eight families of Dicotyledons, (the Ranuneulacex, Magnoliacex, Papa-
veracex, Crucifere, Crassulacex, Ericacese, and Primulacee). I have myself
observed most of these, as well as many other less known cases. To the
latter belong, for instance, the transformation of the carpels into stamens in
Allium Schenoprasum, which seems to occur as commonly in the chives
cultivated in gardens, as the opposite case of the inner stamens turning into
carpels in the cultivated Sempervivum tectorum. This transformation is
exhibited in the chive in the most varied degrees; it is further remarkable
from the fact that the stamens appearing in the place of the three carpels,
have extrorse anthers, while the anthers of the six normal stamens are
introrse, a condition which reminds us of the similar double character of the
anthers in the Laurinew and Polygonex. Strange too, is the occurrence of
three more shorter stamens, which are confluent with the three replacing the
carpels, and which I can only regard as axillary structures like those
occurring in double flowers, (see note, p. 79.) In this case we find inside
the decomposed germen, which has passed over into a staminal formation, a
new more or less perfectly developed whorl, the organs of which alternate
with those of the preceding whorl. Another case, apparently also little
known, but equally frequent, occurs in the cultivated horse-radish (Armoracia
rusticana). ‘The two carpels are here transformed more or less completely
into stamens, while two other organs, absent in normal flowers, make their
appearance as carpels. The reverse case, the transformation of all the
stamens into carpels, is shown by Cheiranthus Cheiri gynantherus, Dec., a
monster which has become a variety in the Paris garden, and for which I
am indebted to M. Gay.

7

98 THE PHENOMENON OF

sometimes triandrous,* also by the Iridee, Graminacex
and Cyperaceze,t Alisma and <Actinocarpus,t Cerastium
semidecandrum, and tetrandrum, Menchia quaternella,
the tetrandrous species of Sayına, the pentagynous
Campanulacex, e. g., Campanula Medium, Drosera, |
Tamariz,§ Viola, &e. On the other hand, an outer
circle of stamens is abortive in Triglochin palustre, while
in Zr. maritimum both cireles are fully developed; in
most of the digynous Solanacez (7. e., with two carpels),
in like manner, while in Mcotiana guadrivalvis the fruit
becomes four-chambered, by the development of both
circles; moreover, in most of the Gentianee and
Apocyneze, the Scrophularineee and Labiate, the genera
of Rutaceze with a double circle of stamens, the digynous
and trigynous Alsinee and Silenee, as well as the penta-
gynous genera Malachium and Agrostemma.**

An inner circle of stamens vanishes, together with an
outer circle of carpels, for instance, in Stellaria media
(pentandra), in most of the Diosmes, Cneorum, Celas-
trine®, Ludwigia, and Isnardia, Circea (?),++ Hederaceee,
Umbelliferee, &c. It is probable that in the Polygones
there is a suppression of 1} to 2 circles of stamens, and
one circle of carpels. In Rosacee, Pomacew, Amygda-
line, Myrtacez, and Philadelphus, there is certainly
a suppression of several circles of stamens at the transition
to the fruit ; probably also we ought to assume two abor-
tive circles between the stamen-formation and the fruit
in the flowers of the Papilionacex. A glance back over

* Juncus supinus is ordinarily triandrous, the variety which is held as
J. nigritellus, Don, is hexandrous.

+ At least in the Cyperine, the Caricine may be different ; see below.

I Alisma and Actinocurpus are rudimentarily enneandrous, like Butomus.

§ The suppressed circle of stamens appears developed in the doudle
Campanula Medium of es In this case the first circle of stamens
becomes the inner corolla, the abortive circle the circle of stamens. The
form and arrangement of the carpels remain unchanged.

|| Both circles are developed in Drosophyllum.

9 In Myricaria (Tamarix germanica, L.) both circles are developed.

** See the ‘Flora,’ 1843, No. XXII, et seq.

Tt See the ‘Flora,’ 1835, I, 179.

REJUVENESCENCE IN NATURE. 99

the examples previously mentioned of the occurrence of
‘abortive circles at the passage from calyx and corolla to
stamen-formation, taken in comparison with the instances
just brought forward, of abortion of leaf-formations at
the transition to the fruit, leads to our remarking that
they are almost throughout derived from different natural
families, which gives rise the observation, that a suppres-
sion at both the said points of transition at once is among
the less frequent cases. ‘Thus abortion occurs merely at
the first point in the Primulacee, Geraniacex, and
Malvacex, solely at the second place in the Rutacez,
Onagrex, Solanacee, &c. Cases where it is met with
in both regions are furnished by the apetalous Caryo-
phyllacee, e. g. Stellaria media apetala, Scleranthus ;
also by the apetalous Leguminose and Rosacez, but
most convincingly in Limnanthes. This genus exhibits
five sepals, and five perfect petals alternating with these ;
next, also alternating, five glandular scales, the traces of
an abortive inner corolla; these are succeeded by two
pentamerous circles of stamens, the outer of which, lying
opposite the petals, are shorter, the inner, opposite the
sepals, larger; finally, five carpels, which are opposite
the inner stamens, and therefore lead to the supposition
of the abortion of one circle.

In many plants, intermediate structures occur in the
position of the abortive circles, between flower and fruit,
softening the abruptness of the passage from the acute and
transitory stamen-formation to the calm and enduring
structure of the carpel. In many cases these transitional
structures are but stunted, as, for example, in the circle
of glands which succeeds the three circles of stamens in
the flower of the cinnamon tree ; very often they are more
developed, as in the two circles of lanceolate, sinuate-
bordered leaflets inside the staminal circles of Aguzlegia,
and the above-mentioned structure of Paonia Moutan.
It is remarkable that these transitional structures some-
times assume completely the shape of an inner corolla.
We have already noted above the affinity of the calyx

100 THE PHENOMENON OF

to the fruit; so, just as in the ascent from calyx- to
stamen-formation, the corolla lies between the two, we
again find the petal formation, as a perigynium, in the
descent from the stamen-formation to the fruit-formation.
In many Limes the similarity between the perigynıum
and the corolla is perfect, while in other species of the
same genus normally developed stamens occupy its place.
The resemblance to petals is less marked in the pert-
gynium of the Byttneriacee and Dombeyacew ; in the
Malvaceze, especially distinctly in Hibiscus, it forms
the inside of the tube, from the outside of which the
circles of stamens pass off at various heights.

Lastly, we have still to consider the cases in which, at
the last stage of transition of the metamorphosis, the
suppression acquires such extent, that the entire stamen-
formation becomes involved, or, on the reverse, this exists,
and the fruit-formation is suppressed. The necessity
of these two formations to propagation, makes it a con-
dition that, in such cases, the plant bears two kinds of
flowers,—staminate (male) and pistillate (female) flowers,
united on the same “stock,” or distributed on distinct
“stocks.” Examples of this kind occur not merely
scattered singly in the most diverse families, but there
are even entire families in which this condition appears as
the rule. To the former belong dicecious species of the
genera Lychnis, Silene, Rhamnus, Rumex, the genus
Rhodiola of the family of Crassulaceze, the genera Smilax
and Ruscus, of the alliance of Lilies, and Zea and Coir
among the Grasses; to the latter belong the Palme and
Cucurbitacee. In all these the male and female flowers
have the same type, but differ in the completion, since
the plant is incapable of combining the contrast of stamen-
and fruit-formation within the ideally limited space of one
flower. In the male flower the leaf-formation smks down
after bringing forth the stamens, without acquiring
power to rise again to fruit-formation ; in the female
flower the latter is attained by an earlier retrogres-
sion of the leaf-formation, suppressing the stamens,

REJUVENESCENCE IN NATURE. 101

whereby space is gained for its new uprising in the fruit-
formation.*

Let us now turn from the examination ofthe undulation
which the metamorphosis of the plant follows in its
greater soarings and subsidings, to the consideration of
the individual steps in which it completes its course, the
single leaves. ‘The leaves present themselves to us as
the single waves in the great stream of vegetable develop-
ment, a stream flowing and ebbing with a periodicity
regulated by law. As we have regarded the sprout as
the first subordinate Rejuvenescence of the plant, as we
have further considered the regions and formations on the
sprout as circles of Rejuvenescence of the metamorphosis,
so have we now to examine the individual leaves (with the
internodes bearing them,) as links of Rejuvenescence
within these larger circles. In this sphere, the theory of
Rejuvenescence already presents itself to us in a declared
form and developed into a system in recent scientific
literature,f but truly, in spite of much that is to the point

* At the same time, all diclinous flowers do not behave in the same way;
on the contrary, there exist great: and essential differences in the structure
of flowers with separated sexes, which, however, are often difficult to make
out. While in the cases above considered the unisexual flower presents
itself merely as a one-sided development of an hermaphrodite flower, its
origin depends in other cases, like the sex in animals, ou the different mode
of development of parts, which, according to their position in the flower, are
like, as is the case, for example, in the Willows, in which the same leaves
appear in the male as stamens and in the female as carpels. The observa-
tions which I have made on the so-called hermaphrodite flowers of Carex, in
particular of Carew stricta, seem to testify the same for this genus. In
Hydrocharis we meet with a case which stands mid-way between the two
mentioned modes of origin of unisexual flowers. In this plant the flower is
composed of six alternating trimerous whorls. The first and second (calyx
and corolla) behave alike in the male and female flowers. The third, fourth,
and fifth, appear as perfectly developed stamens in the male flower, while
the sixth consists of blunt processes which sometimes have been called stami-
nodia, sometimes abortive pistils. Inthe female flower, on the contrary, the
third and fourth whorls appear as blunt processes, (staminodia and nectaries
of authors) while the fifth and sixth become fully developed in the form of
carpels,

: C. H. Schultz, ‘Die Lehre von der Anaphytose oder Verjiingung der
Pflanzen, ein Schüssel zur Erklarung des Wachsens, Blühens und Fruch-
tragens der Pflanzen,’ 1843; and ‘Neues System der Morphologie der
Pflanzen nach den Organischen Bildungsgesetzen,’ 1847.

102 THE PHENOMENON OF

and suggestive, on the whole in a manner of little use,
because deficient in firm morphological foundations.*
Schultz’s theory of Rejuvenescence makes strikingly
prominent the difference between animal and vegetable
Rejuvenescence: animals repeat, as Schultz expresses it,t
the contrast of living and dying, the unity of which forms
the Rejuvenescence, in all their internal organs, and there
thereby undergo continuous dissolution and reformation,
the effete parts being at the same time cast off like a
husk. Plants, on the contrary, never rejuvenise an
internal organ once completed, but repeat the contrast of
living and dying only in their outer members, advancing
constantly beyond the completed structures to new pro-
ductions. This peculiarity lies in the nature of vegetable
growth, which goes on solely by repetition of the same
parts, by Anaphytosis. For Schultz to combat the theory
of metamorphosis, as he does, by this doctrine of the
anaphytosis of plants, is an inconceivable contradiction,
cutting off all purpose or aim from the doctrine itself.
The doctrine of anaphytosis, which is characterised as the
theory of the constant self-rejuvenescence of plants
through living repetition of the same parts, aiming at
the object of demonstrating the laws of this repetition
characterising the whole growth of plants, cannot really
stand in contradiction with the theory of metamorphosis of
plants, which, in like manner, leads back to the original
likeness of the vegetable parts or organs repeating them-
selves in various forms.} Since the links or members of
the Rejuvenescence of the plant (Anaplıyta) are not
exactly of similar character as they succeed one another,

* This is not the place to carry this out further by demonstration of the
morphological errors in the said works; the botanist accustomed to mor-
phological researches finds proof of the above assertion in every paragraph,
e. g., in § 34, where leaves in leaf-axils, and buds in branch-axils of forked
stems, are spoken of. See also the critique of Mohl, in the ‘ Botanische
Zeitung,’ 1843, p- 667.

f Die Lehre von der Anaphytose, 89.

+ “The plant represents the most varied shapes by modifications of a
single organ.” Goethe, ‘Metamorph.,’ § 3. :

REJUVENESCENCE IN NATURE. 103

but present themselves in a series of modifications, the
theory of metamorphosis is necessary to the completion
of the doctrine of anaphytosis, since its object is to
demonstrate the laws ruling over the various modes of
appearance of essentially similar parts, the definite course
of transformation of the anaphyta progressing through a
series of stages. As the animal combines a metamor-
phosis with its internal process of Rejuvenescence, so
does the plant also with its external, only the metamor-
phosis of the plant, in correspondence with the peculiarity
of its anaphytosis, does not present itself as an internal
recasting of the organism, as in the animal, but as an
externally projected, many-stepped process of develop-
ment. A doctrine of anaphytosis without recognition of
metamorphosis, robs the plant of its inmost principle of
life. —the principle of development, the graduated reve-
lation of the internal foundation of its existence; it
denies progress and aim in the processes of vegetable
construction, and is compelled to ascribe the difference of
the links of the Rejuvenescence to the accident of external
influences, while this is rather the expression of the
gradual triumph of the specific inward essence over
external nature.

If it be true that the plant runs through its metamor-
phoses in a process of Rejuvenescence characterised by a
series of stages and links; that, to use Schultz’s expres-
sion, it possesses a phylodom, progressing by anaphytoses,
our first object must be to define the links of the Reju-
venescence accurately. But this fundamental condition
of a correct theory of Rejuvenescence, is exactly that in
which Schultz’s exposition is deficient. The “anaphyton,”
or simple link of Rejuvenescence, by the continued repe-
tition and manifold combination of which the whole
structure of vegetables is explained, is indeed theoretically
characterised as a totality fitted out with all essential vital
apparatus, and as an independent vegetable individual ;
in what, however, we really discover how the anaphyta
proceed one out of the other, and how they combine, is

104 THE PHENOMENON OF

nowhere clearly shown ; it is termed a universal morpho-
logical or phytodomic element, the primitive link or
element of all external organs of plants, from the varied
combinations of which are formed the root, stem, and
leaf, which have been incorrectly regarded as essentially
different organs of the plant ;—but where the limits of
the single anaphyton are to be found in these structures,
how it is to be recognised in its combinations and
separated as an independent constituent part, remains, in
most cases, altogether obscure. Much of what Schultz
ascribes to the anaphyton is applicable to the cell; but
Schultz’s anaphyton is not the cell, for Schultz imagines
therein a morphological unity, in which it is essential to
embrace the various principal modifications of the tissue,
as organs of the individual life. Such a morphological
unity, the varied combinations of which would explain
the variety of the external parts of plants, has, in
reality, no existence whatever, as unprejudiced examina-
tion readily shows. When we trace the anaphyton in
Schultz’s “construction” of vegetable structure, we find the
most diverse things thrown together without the slightest
morphological tact.* We meet with the anaphyton at
one time as an internode bounded by nodes, or as an
articulated piece of the petiole of a compound leaf; at
another time, however, as any given piece of an inarticu-
lated trunk bearing a bud, or capable of producing one ;
or even as a totally arbitrary piece of a root (as such
without articulations), which is said to be composed of as
many anaphyta as pieces it can be cut into capable of
producing adventitious buds; further, the anaphyton
appears as a longitudinal strip of a flat leaf ;+ lastly,
actually as a circular Rejuvenescence-layer in the interior

* Schultz’s doctrine is in this respect certainly much more variegated
than the “chaotic hash of the theory of metamorphosis.” ‘Neues System,’
p. xvii.

T Broad flat leaves are said to originate by lateral (sympleuric) fusion
(symphytosis) of normal stalk-shaped anaphyte. ‘Neues Syst. der Morph.,’

page 2.

REJUVENESCENCE IN NATURE. 105

of the perennial trunk.* ‘The parts of the flower again
are regarded partly as simple azaphyta, partly again as
composed of a number of anaphyta.t

When we gather all this together, we cannot wonder
that even an admirer of Schultz’s doctrine of the Ana-
phyton says, that it is a Proteus, which we cannot grasp,
and which everywhere slips away from us, yet lies at the
base of all actual shapes. To those who test the new
system for themselves, in the living plant, it will certainly
be clear from Schultz’s explanation, that this Proteus is
a mere thing of the imagination, existing neither by itself
nor in its combinations, which are forged out of actuali-
ties found in the most diverse sections of the vegetable
organism: sections partly existing as such, partly purely
imaginary. The correct perception that there exist in
the plant multifold phenomena of Rejuvenescence, re-
peated in diverse morphological regions, and subdivisions
(Gliederungen) conditioned thereby, is completely reversed
by Schultz’s system, in that all these perceptible sub-
divisions (not to consider the merely hypothetical) are
regarded as essentially like members of the plant, and

* < Anaphytose,’ § 41.

+ The flower is to be couceived only physiologically, and not morpholo-
gically (‘Anaphyt.,’ p. xi), and yet its formation is explained from morpho-
logical elements, 7. e. anaphyta (ibid., p. 62). Although composed like
the individual parts of the plant, that is, the parts of the vegetable
“stock,” of anaphyta, the parts of the flower are said to possess only an
apparent and no real similarity to these, and to be essentially different from
them (p. 67). Since the parts of the flower, as azaphyta, are explained, at
the same time, like the individual parts of the plant, as independent indi-
viduals (p. 92), and since the whole plant is said to repeat itself, with all
its essential functions, in each anaphyton, it is impossible to see, from
Schultz’s doctrine, whence comes the asserted essential difference of the
anaphyta of the same plant. Schultz’s own distinction, namely, the anaphyta
of the vegetable “stock,” as mere individual (!) (asexual) individuals, and
the anxaphyta of the flower (exanaphyta) as sexual individuals, cannot be
regarded as essential, and removing all real similarity, since, on the one
hand, the parts of the flower must still have an individual existence, and, on
the other hand, the axaphyta of the vegetable “stock” must have ascribed
to them, from the production of new unaphyta, not merely individual existence,
but power of propagation. Hence Schultz’s opposition to Metamorphosis
appears wholly groundless on this side.

+ Vide ‘Botanische Zeitung,’ 1843, p. 741

106 THE PHENOMENON OF

misused for an atomic theory of anaphyta (anaphyten-.
atomistik), which can far less attain to the comprehension
of the living course of the shaping-out of the plant,
developing the parts out of the whole, than even the
atomic theory of cells, since its atom is not a real, like
the cell, but an imaginary unity.

The repeated attempts to represent the plant as a series
of leaves growing one out of another forwards, and firmly
intergrowing with one another backward, appear to rest
more definitely upon the real and essential subdivisions
of the structure of the plant, and it is no great step from
here to the idea that the plant is to be regarded as a
series of generations, the individuals of which are repre-
sented by the leaves, and the metamorphosis of the plant
as an alternation of generations, through which, after
numerous preparatory and asexual individuals, the gene-
ration finally arrives in the flower at the formation of the
sexual individuals closing the series.* This attempt to
trace back the whole plant to the leaf-formation, has been
carried out most ingeniously by Ernest Meyer,t and
recently supported through anatomical researches by
Hanstein.t

Here also we refer Gaudichaud’s$ accounts of the
morphological construction of the plant through repetition
and combination of individually independent vegetable
elements (Phyta,) each of which is regarded as composed
of three regions; leaf above, internode in the middle, and
root below,—as also the building up of the plant of
stages (or storeys) as explained in the essays of Hoch-

* See the explanation, according to this theory, by Steenstrup, in his
“Alternation of Generations in the Lower Classes of Animals,’ p. 128.
(Ray Society’s Publications, 1843.)

‚TE. Meyer ‘Die Metamorphose der Pflanze und ihre Widersacher,’
Linnea, vi (1832), p. 401.

{ Hanstein, “plantarum vascularum folia, caulis, radix utrum organa sint
origine distincla, an ejusdem organi diverse tantum partes?” Linnea,
xxxi (1848), p. 65.

§ Gaudichaud ‘Recherches sur l’Organographie, la Physiologie, et ?Or-
ganogénie des Vegetaux,’ 1841.

REJUVENESCENCE IN NATURE. 107

stetter on the structure of the grass-plant.* All these
attempts to compose the plant of leaves are wrecked upon
the fact of the existence of the stem as an original, inde-
pendent and connected structure, the more or less distinct
articulation of which certainly depends upon the leaf-
formation, but the first formation of which precedes that
of the leaves. The graduated metamorphosis of the plant
requires the stem as a bridge between the steps; the
theory of the arrangement of leaves requires it as the basis
upon which the leaves form their regulated ranks; the
comparative morphology of the lower plants demonstrates
the independence of the stem, since it never shows leaves
without stem, although certainly stem-formation without
leaves ;t finally the history of development brings the
stem before our eyes, in its earliest period of formation,
as the visible foundation, out of which the leaves are
developed.

* ‘ Jahreshefte des Vereins fur Vaterländische Naturkunde in Wurtem-
burg,’ 1847, p. 1; and 1848, p. 144. The leaf and the segment of the halm
beneath it form, according to Hochstetter, a whole, which he calls a stage or
storey (Stockwerk), and which consists of three parts, the /oo¢ (internode of
the halm), the Zruz% (the leaf-sheath), and the head (the blade of the leaf).
Each new stage is produced from its predecessor by a branch being given
off at the ae between the foot and the trunk. In this way each leaf is
regarded as the terminal prolongation of the internode of the stem, which
original relation is supposed to be clearly preserved in Juncus, on the round
stalk-like and erect highest leaf (according to Hochstetter, homologous with
the point of the sterile halm), from which we see the inflorescence escape
laterally through a slit. Hanstein also regards the leaf as terminal, since he
asserts that each new leaf originates through uplifting of the centre of the
point of vegetation: “Puncli vegetationis centrum in novum extenditur
Jolium,” \. c., p. 83. .

+ In the higher classes of plants even we meet with cases of the develop-
ment of the stem without leaves, as well-known in tendrils and thorn-
structures. The sterile halın of the Rushes (Juncus conglomeratus, &e.)
affords an equally familiar, though less noticed case.

+ The recent researches on the commencement of leaf-formation leave no
doubt on this point. See the works of Schleiden, especially on the origin of
the cotyledons in the embryo and the coats on the nucleus (‘ Wiegmann’s
Archiv,’ 1837, and elsewhere) ; Von Mercklin (‘Zur Entwicklungsgeschichte
der Blatt-gestalten,’ 1846:—on the development of the forms of Leaves,
trans. in ‘Ann. des Se. nat., 2d ser. Botanique,’ tom. vi, p. 215, 1846); Adr.
de Jussieu, on the formation of the embryo of Monocotyledons (‘ Ann. des Sc.
nat,’ Juin, 1839); Duchartre, on the organogeny of the parts of the flower
of the Onagracex, Primulacee, Malvacex, Nyctaginez (‘Ann. des Se. nat.,’
1842-4-5-8.) Even in the Ferns, in which the leaf-nature of the frond, as

108 THE PHENOMENON OF

A more detailed examination of the stem from these
four points of view, would lead us too far from our subject ;
but it may be permitted to discuss somewhat more closely
the first point, the import of the stem in reference to
a theory of metamorphosis assuming a vital continuity
and not an atomic composition of the stages. We have
above characterised the leaves as those parts, in the re-
peated formation of which is especially expressed the
Self-rejuvenescence in vegetable life, and through the
successive emergence of which the metamorphosis acquires
its graduated structure. That this graduated structure
requires a connecting organ, different from the leaves,
and not formed from them, an organ which is not lost
in the individual stages, but rather carries up the process
of development beyond the one-sided development of the
stage,—this it is which we would here briefly put forth, so
that we may acquire a basis, out of and upon which the
undulation of the metamorphosis flows. A general
characterisation of the fundamental organs, distinguished
by essential differences in the direction of development,
such as the general contemplation of vegetable structure
and vegetable life in its relations to external nature
impresses them upon us, may hence not be misplaced here
as a preliminary settlement of our position (Orientirung).
The difficulty of comprising the phenomena in such a
general view will serve as an excuse for the imperfection
of its execution.

it is called, has been often questioned and disputed, I have satisfied myself
beyond the possibility of doubt of the excentrical origin of the leaves around
a central apex of the stem. The often ell-long creeping subterraneous
stolons of Struthiopteris germanica are clothed with scale-like cataphyllary
leaves, which on the points of the runners coming up above ground, pass
ER into the ordinary euphyllary leaves of the erect stem. They are
arranged according to the 3 type, about an inch distant from each other,
1 inch long, but decurrent for a length of about 2 inches; the unde-
veloped leaves situated on the nascent points are closely crowded. Taking
away all the leaves already more than 1 line long, there remain still about
8 rudiments, the outermost of which are about 3, 4, 3 of a line high, the rest
scarcely measurable. The four innermost appear as slightly-vaulted papilla,
gradually diminishing in size around a central papilla, which is the largest,
and therefore cannot possibly be mistaken for one of them.

REJUVENESCENCE IN NATURE. 109

The Vegetable kingdom, like every kingdom of nature,
each of its divisions, each genus, and each species, has, in
virtue of its peculiar internal essence, its special desti-
nation. With this special purpose it enters into the
circle of the multifold life of nature, which meets it partly
as a friend, partly as a foe, partly favouring and bearing
it up towards its object, partly limiting and interrupting
the carrying out of it. Hence, every created thing
which, in realising itself, enters into the totality of natural
life, has to overcome the detracting influence of the lower
kingdoms, above which it has to elevate itself. The
vegetable kingdom is preceded by the kingdom of the
shaped and shapeless elements, the kingdom of inorganic
nature. We behold in this, the kingdom of universal
combination in rest and motion, the kingdom of gravity
and cohesion, of universal mechanical antagonism ; in
detail the kingdom of the homogeneous and unchangeable,
in which every change of matter is at the same time a
destruction ; and, where it attains to shape, the kingdom
of fixed and motionless form. Throughout all this
region there is indeed a development of the whole through
detached shaping out of the individual parts, but the
individual parts have no progressive vital development, no
transformation as such, and no Self-rejuvenescence of
being. But above this kingdom of bondage the plant rises
in more emancipated development of life. It acquires shape,
not through a mere act of formation, but through a pro-
cess of development running through different periods,
in which it overcomes more and more inorganic nature
and its bondage, subordinates it as a means, bringing the
peculiar, more highly gifted nature, in it and through it,
to ever freer and more perfect unfolding. We see the
gradual solution of this problem realised in the metamor-
phoses of the plant. The elevation above the earthly,
merely passively physical, is expressed even in theascending
growth,* which is constantly combined with the progres-

* Stems growing downwards or creeping horizontally only occur in the
retrogressive or in persistent low stages of metamorphosis.

110 THE PHENOMENON OF

sive metamorphosis. The single organs of this graduated
elevation, the links of the ascending growth, in which the
internal impulse towards an increasingly purer and more
victorious representation of its true nature finds its
graduated accomplishment, are the Zeaves. It is a pe-
culiarity of vegetable life that it fixes itself at each stage,
bringing each to its own permanent and strictly limited
development. Hence each leaf is a thing limited and
unalterably fixed at a determinate stage of the metamor-
phosis.

Since, then, the plant does not exhaust its life in the
single representation, this being rather only a stage beyond
which the metamorphosis advances to new representations,
some organ must exist serving as the means for this
advance, in which the life is not expended in the estab-
lishment of the stage, is not terminated in a partial
realisation, but which, retaining its independence, secures
a future development, rises beyond each representation
until the last, as a more active central point, constantly
renewed and sending out new radii, and only loses its
import as an individual centre of formation when the
last and most perfect representation, the aim and con-
cluding structure of the metamorphosis, is attained.
This organ of the plant is the stem or axis. The
stem is not ordinarily continued beyond the last radii,
coinciding with the limited or terminal stage. Its
terminal prolongation is lost, without any final struc-
ture belonging peculiarly to itself, among the last
leaves of the sprout, whether this concludes with a
flower or not, m the former case, therefore, among
the carpels.* But this must not be supposed to mean

* Among the exceptional cases in which the stem acquires a development
rising beyond thelast leaf, or, if it is a lateral sprout, appears in an independent
structure devoid of any leaf-formation, becoming itself developed in a radi-
ating manner, are: 1, the free central placenta; 2, emergence into tendril-
formation; 3, emergence into thorn-formation ; 4, emergence into bristle-
formation (Setaria, Chenopodium aristatum); 5, the soft needle-like ramifi-
cation of Asparagus; 6, the leaf-like summits of the stems and branches of
Ruscus, Medeola asparagoides ; and 7, the above-mentioned sterile halm of

REJUVENESCENCE IN NATURE. 111

that the stem takes no part in the metamorphosis ; for it
is rather in the terminal prolongation of this, that the
gradual changes of purpose lying at the foundation of
the metamorphoses are prepared, to pass over from it
to the developing radii, so that the stem shows, more or
less strikingly according to the structure of the leaves,
the characters and functions of those leaf-formations of
which it constitutes the support. Thus we see the
lower stem colourless and devoid of stomates, like the
cataphyllary leaves ; the middle stem green, and furnished
with stomates, like the euphyllary leaves; that part of the
floral axis which bears the carpels often developed even
into a fruit-structure (Fragaria). Thus stem and leaves
together form one whole, the ascending vegetation, in
which the metamorphosis is revealed, throwing out its
halting points in the leaves, and advancing, through the
medium of the stem, to further stages.

Opposed to the ascending vegetation (Pflanzenwuchs),
as a whole, stands the roof, without which the former
would be baseless. In the universal bond of nature all
the higher must rest upon the lower, grow forth within
and out of this, find its basis and seek the material for
its realisation in the lower realm, and thus as it were,
descend into and absorb the lower, which it is to over-
come. This necessary vital direction, first of all acting
in opposition to the true purpose, but in the sequel be-
coming again subservient to it, finds its representation
in the root. The root, as a downward growth, is produced
in contrast not merely to the stem, but to the. whole
ascending growth of the plant; it originally follows
simply the attraction of gravitation in its growth, pene-
trating perpendicularly downwards, and is diverted into

Juncus, which presents itself alone, in place of the euphyllary formation,
bearing only cataphyllary leaves at its base. The development of these
enormous leafless stem-summits deserves a closer investigation ; so far as I
could trace it, I found nothing which could warrant the idea that these
green halms were leaves, in particular no sheath at their base. The smallest
and youngest that I could dissect out always appeared as elongated conical
points, and no other punctum vegetationis could be distinguished.

112 THE PHENOMENON OF

deviating directions only in its branches. Thus it gives
the plant its basis and connection with the inorganic
soil, and especially supplies that material, by the assimi-
lation and subordination of which the entire plant
becomes realised. In correspondence with its direction
of growth, it forms a contrast to the total ascending de-
velopment of the plant ; it therefore has no metamorphosis.
For the same reason it is devoid of leaves, these being
the steps in the course of the metamorphosis.

Thus, then, stem, leaf, and root present themselves as
essentially different parts of the vegetable organism, as
its fundamental organs depending on the difference of
the directions of development of vegetable life. ‘The sure
and exact distinction of these forms the basis of Morpho-
logy. ‘That the study of the lower plants leads us to
structures in which the different directions of vegetable
life do not appear clearly distinguished, is no reason why
we should deny their essential and inconvertable differ-
ence when they present themselves really separated, as is
almost everywhere the case throughout the higher classes
of the Vegetable kingdom.

Leaves and stem form together, as above remarked,
one whole, opposed to the root; if we regard the leaves as
rays, the stem forms the centre, necessary to the idea of
the rays ; if we regard them as waves, the stem represents
the level on which the undulations originate, forming the
troughs between the waves: a mode of viewing the phe-
nomena suggested by the theory of the arrangement of
leaves. Not only in the fully-developed leaf, do we see that
itis not sharply cut off from the stem, but runs gradually
into it, as shown in the formation of the pulvinus, in decur-
rent margins, &c.: this is indicated even in the earliest
appearance of the leaf, primarily a scarcely distinguishable
papilla, extending laterally into a little ridge (running back
as it were into the stem), the papilla sinking down outside
(below) quite gradually into the stem. How the leaf is
really formed, how it takes its first origin in the stem, and
by growth emerges from this, is a problem which the

REJUVENESCENCE IN NATURE. 113

research, recently so industriously devoted to the history of
development, has not yet been able fully to solve. The idea
of Schleiden, that the leaf is pushed out, as it were, from the
stem, the apex first emerging, and the lower parts being
gradually extricated by development at the base,* is devoid
of exact demonstration, which can only be given by a com-
plete history of the development, accurately illustrating
the succession of the individual cells, of the apex of the
stem, and the rudiments of the leaves arising from it,
which certainly exist before they are elevated as papilla.
The assertion of Schleiden, that the leaf is formed by a
process of cell-formation advancing from the apex to the
base, has been contested by Nägeli,f who, resting on
complete observations on the formation of the leaf in the
Floridez,. Characeze, and Mosses,{ sets up the contrary
‘doctrine, that the original growth of the leaf advances by
cell-formation at the apex and at the circumference, that
is, from the base upwards and outwards, and that only
the later growth, connected with final completion of the
structure of the leaf by expansion of the cells, begins at
the point and circumference, and progresses towards the
base. How far these results, derived principally from
the Cryptogamic plants, are applicable to the leaf-forma-
tion of the Phanerogamia, can scarcely be safely deter-
mined, from the deficiency of researches on the latter.
That supplementary cell-formation, presenting itself in all
or only isolated parts of the first cellular structure, fol-
lowing the original cell-formation (doubtless progressing
according to accurately defined rules in the higher no
less than the lower plants), that supplementary develop-
ment which Nägeli calls abnormal or accidental, appears
to.be of great importance to the ulterior development of

* Schleiden, ‘ Grundzüge du Wiss. Botanik,’ ii, 118, (2d Ausg.) ‘ Prin-
ciples of Scientific Botany’ (London, 1849), p. 281.

+ ‘Ueber das Wachsthum und den Begitl¢ des Blattes,’ Zeitschr. f. wiss.
Botanik, 1847, 153; ‘ Wachsthums-geschichte der Blätter der Laubmoose,’
Ibid, 1845, p. 175.

+ With regard to the two last-named families, I can fully confirm Nageli’s
observations through my own.

, 8

114 THE PHENOMENON OF

the leaf of the Phanerogamia ; but that Schleiden’s theory
of leaf-formation is only partly warranted, even in this
second stage of growth, is shown by Grisebach’s dis-
covery, that several points of vegetation or foci of develop-
ment frequently present themselves within the leaf, and
an intercalary cell-formation occurs not only at the base,
but at various points.* Even the last stage of growth of
the leaf, depending on the mere expansion of the cells,
does not always, or in all parts of the leaf, progress in
the descending (centripetal) direction, as followed indis-
putably, even before Grisebach’s researches, from the
observations of Steinheil (especially on the leaf of the
Magnolias) and Munter (on pinnate leavesf), although the
difference between the growth by cell-development and
cell-formation was not actually distinguished in them.t

The general and partial gradual unrolling, advancing
toward the apices, and the final expansion of the Fern-
leaf connected with this, is a well-known phenomenon,
which has been incorrectly regarded as an evidence
against the foliar nature of this organ.§

* Grisebach, “Beobachtungen über das Wachsthum der Vegetations
organe in Bezug auf Systematik.” (Weigmann’s Archiv, 1844, 134.)

+ ‘Observationes sur la mode d’accroissement des feuilles.” (Ann. des Se.
nat. 1837.)

+ “Beitrag zur Lehre vom Wachsthum der Pflanzen,’ Bot. Zeit., 1843,
. 785.
L § Especially remarkable, in this respect, are certain Ferns, in which the
points of the leaves are never totally unrolled, as in the narrow, simply
pas Platyzoma microphyllum, and the Jamesonie resembling them in
abit (e. g. J. imbricata, Hook. et Grev., t. 178, scalaris, cinnamomea, verti-
calis Kunze, ‘Die Farrnkrauter in Colorirten Abbildungen,’ t. 71 and 82).
Still more remarkable are many species of Gleichenia and Mertensia, in which
the development of the leaf is arrested above the first pair of pinnules (and
in multipinnate rudiments often repeated in several degrees of the ramifi-
cation), so that the point, seeming to form a bud in the bifurcation, either
remains permanently undeveloped, or is only unfolded in the succeeding
season, and then again in like manner only imperfectly. This sectional
development of the leaf, in which we behold one of the most remarkable
henomena of Rejuvenescence within the leaf itself, appears capable of
asting through many years, on which head it would be very desirable to
obtain more accurate information from observers in the native countries of
these Ferns (see Kaulfuss, ‘Das Wesen du Farrnkräuter”), 1827, p. 36).
That the leaves of these Ferns do not possess, however, as might seem, an
unlimited growth, is proved by the leaves of the young Mertensie with a

REJUVENESCENCE IN NATURE. 115

The tendrils of the Cucurbitacez, certainly belonging
to the leaf-formation, behave, leaving out of view the
suppression of the blade-formation, exactly in like man-
ner, and the pinnate leaves of the Dicotyledons have not
only a centrifugal expansion-growth of the petiolar
apparatus; but the lateral leaflets unfold distinctly in
ascending order, while at the same time each individual

leaflet completes its own growth by a centripetal ex-
pansion.*

In spite of the imperfection of our insight into the
laws regulating the formation of the leaf, we may at
least regard it as certain, that the leaves are developed
forth from an axis formed before them, and that this
axis, whenever leaf-formation occurs, is developed into a
stem after the rudiments of the leaves have come into
existence ; it may be further regarded as certain, that
the formation of the leaves is not simultaneous but suc-
cessive ;+ so that between two following leaves there
always exists at the outset, a separating structure, the
axis, permanent as such, whether it may be developed as
an internode or not. If we conceive the leaf in relation

similar apiculated terminal structure, of which Martius (‘Icones plant.
crypt.,’ t. 60, ii) has represented an interesting series, but erroneously
referred to a distinct species (JZ. pumila). The Hymenophyllum interruptum
figured by Kunze (‘ Anal. pteridograph., t. 30), likewise deserves mention
here.

* The phenomenon may be seen especially well in the Mahonie with
pinnate leaves, the lower pinnules of which are already expanded, green,
and coriaceously hardened, while the upper are still scarcely half as large,
half folded together, reddish, and soft.

(Vide also ‘Proceedings of the Linnean Society of London,’ May 6th,
1852, in a paper by Dr. Alexander on the leaf of Guarea grandifolia, Dene.
In this the upper leaflets are developed after the lower have fallen off,
periodical growth at the apex of the petiole going on for several years.—A. H.)

f This holds good even of the leaves of whorls, as transitions and sub-
stitutions of verticillate and spiral arrangements sufficiently testify.
Although recent observations on the development of the parts of the
flower describe the circles of papilla, forming the earliest representatives of
the circles of the flower, as coming to light simultaneously in all the segments,
we must remember that these papille are by no means the earliest rudi-
ments of the leaf-formation, but that to solve this question by means of the
history of development, it would be necessary to go back to the origin of
the cells, or groups of cells, which subsequently rise up as papille.

116 HE PHENOMENON OF

to the axis, as a ray, or in relation to the spiral series to
which it belongs, as a wave, we recognise in any case, in
the intimately connected origin of the stem and leaf, an
alternation of emerging and retiring formation, of rising
and sinking, radiation and concentration ; and this it is
which we have characterised above as a course of de-
velopment advancing in repeated acts of Rejuvenescence,
as it were in an undulating flow of the metamorphosis.
This would be the place to examine the definite pro-
portions which the leaf-formation adheres to in its spiral
undulation, and the conditions of arrangement of the
leaves arising from these; to trace them from the simple
rudimentary plans (3, 3,) with which the plant, as a whole,
commences and which are mostly repeated at the begin-
ning of a new branch, through all the complications
which come in during the progress of the metamorphoses,
and mostly attain their maximum in the hypsophyllary
region ;* then, further, to show how the simpler plans
G, 3, %,) recur, but in cyclic combination, in the flower,
how here a new series of complications is established in
the harmonious combination of the cycles, and how finally
in the fruit, the arrangement frequently returns to the
simplest condition. But to carry this out would demand
an exposition of the theory of Phyllotaxy, which would
far exceed the limits allowable in the present treatise.

Note.—The more recent researches on the Phyllotaxy
of Plants will be found compared in Schleiden’s ‘ Grund-
ziige, 2teAusg.ii, p.177 (‘Principles of Botany,’ pp. 263-6),
to which are to be added, a later treatise by the brothers
Bravais (‘Essai sur la disposition générale des feuilles
rectiseriées,’ 1840), an essay by the Swede Silverstrahle
(translated in Hornschuch’s ‘Archv. scandinavischen
Beiträge,’ 1, p. 382), agreeing in its conclusions with the
first treatises of the brothers Bravais; and the works of

* Vide Composite, Dipsacee, Plantaginex, Proteacex, Pipe
Zingiberacese, Cyperacee, Aroidex. peracee,

REJUVENESCENCE IN NATURE. 117

Naumann, which, originally scattered through” Leonhard
and Bronn’s “Jahrbuch der Mineralogie’ (1842), and
Poggendorff’s ‘Annalen’ (1842-43), were subsequently
collected by the author -into an independent treatise
(Ueber den Quincunx als Grundgesetz der Blattstellung,’

1845). Since I have indicated the occurrence of simpler
and more complicated conditions of the arrangement of
leaves, and a determinate cycle in which these ¢ appear in
the plant, I may be permitted to introduce here inci-
dentally an observation on the actual existence of series
of different conditions of arrangement, as asserted in
Schimper’s, and my own works, but questioned in the
essays of the brothers Bravais. I feel the greater in-
clination thereto from a remark of Schleiden (‘ Grundz.,’
p. 176; ‘ Principles,’ p. 265), who characterises the theory
of the Bravais, who sought to trace back to a single,

irrational angle’ of divergence, alike for all, the modes of
arrangement regarded by us as different and expressed
by a series of rational divergences, as far preferable,

since it indicates a simplicity of the law, and under like
possibilities that explanation is always to be preferred
which embraces the greatest number of cases under one
point of view. But the theory of rational divergences
which first recognised as such the multiformity of the
cases which observation reveals, and then strove to
subordinate them to a general law, should have been
upheld on this very ground, in opposition to a theory
which, in contradiction to itself, first denies the multi-
formity of the cases, to insinuate under them an ab-
stract unity, and subsequently (in the second part)
cannot avoid admitting that the rational and in reality
dissimilar cases do occur in plants. To deny the multi-
formity of nature without sufficient proof is certainly not
the right way to introduce unity of law into phenomena.
‘The assertion of the Bravais that all supposable arrange-
inents of leaves of the main chain are formed on a plan of
equal irrational divergence, is just as contrary to nature
as a system of crystallography would be that denied the

118 THE PHENOMENON OF

existence of all the forms of a regular system bounded by
a definite number of surfaces, on the ground that they all
belonged to a single series terminating in the sphere, a
surface without any boundaries. I am far from intending
by this to take away all value from the labours of the
brothers Bravais; the more complicated modes of ar-
rangement are often so difficult to distinguish that the
doubt as to their existence, as actually different, is often
readily explicable, but, on the other hand, in the simple
conditions, there cannot be the slightest doubt that they
exist in the greatest mathematical accuracy, which indeed
is admitted by the Bravais themselves. Hence arises
with the Bravais a diversity of explanation of phenomena
which evidently belong to the same series, a circumstance
which by no means harmonises with the formulary praise
which Schleiden gives to the theory of Bravais. Schleiden
would certainly not have arrived at such a judgment had
the subject of phyllotoxy been more experimentally
familiar to him. At the same time, the question here is
not so much of the preference as regards method of a
theoretical exposition, as the establishment of a series of
facts. I cite in support of my own convictions, gained by
many years’ study of the modes of arrangement of leaves,
an observer whose trustworthiness is declared by most
important labours in an analogous field. Naumann has
not the least doubt of the actual and distinguishable
occurrence of most complicated conditions of arrangement.
4, &, ¥4,) and refers the incredulous to the investigation
of the Cactaceze and Composite, remarking that in the
sun-flower, a blind person will be able to distinguish the
above-named allied plans of arrangement with the fingers,
although they depend upon immeasurably small differences
in the angle of divergence (Poggend. ‘ Annal.’ 1843, p.
554—55). According to my own and Naumann’s
(Ueber den Quincunz, pp. 710—71) observations, not only
2 and 3 occur in the Cactez but also 3 & &, in a manner
which even Bravais could not help acknowledging as not
merely apparently but actually rectilinear and rational.

REJUVENESCENCE IN NATURE. 119

These most clear and decisive cases belong chiefly to the
genus Zechinocactus, in which, in combination with a
most crowded arrangement of the leaves, the pulvini of
the leaves are blended in vertical lines, so that these pre-
sent themselves more clearly than all oblique lines. If,
then, in another genus of the Cactaceze (Mamillaria), the
usually still more complicated modes of arrangement are
less easily and surely distinguishable, because the leaves
are not so closely crowded and the pulvini are separately
developed, we certainly must not conclude from this that
we have here a different irrational mode of arrangement,
essentially distinct from the rational arrangement of the
Echinocacti. As regards Naumann’s method, of ex-
amining, measuring, and naming the arrangement of the
leaves from the point of view of the vertical lines, it may
be added that within a certain domain this has the same
practical applicability as the mode of definition and de-
nomination founded on the fundamental spiral; but if we
go back to the genetic succession of the leaves, which is
indubitably represented in the fundamental spiral, Nau-
mann’s method appears contrary to nature. While on
the one hand it appears to afford a simpler explanation of
the verticillate arrangement, on the other hand it is inca-
pable of expressing, even in the formula of nomenclature,
the actual and essential connection of the verticillate and
spiral arrangements as the transitions in the plant demon-
strate them, whence it must appear especially useless in
the department of anthonomy or construction of diagrams
of flowers. Schleiden further makes the objection to the
whole study hitherto of the phenomena of the arrange-
ment of leaves, that it has kept solely to fully-developed
plants, instead of tracing the subject in the history of
development, whence all theories are devoid of safe foun-
dation (l. c., p. 175, Transl., p. 264); in this he is partly
right and partly wrong, for everything has its time.
What is requisite in the first place is an actual review of
the conditions of arrangement of leaves occurring in the
vegetable kingdom, the mode of their occurrence, their

120 THE PHENOMENON OF

distribution in plants, their transitions and alternations,
and all this can only be afforded by a more or less per-
fectly-developed condition of the plant. A sufficiently
large number of leaves must have been formed before we
can safely judge of their arrangement, since a measure-
ment of the divergence of the earliest rudiments of the
leaves is as impracticable as every later direct measure-
ment. Hence the investigation of the earliest rudiments
in reference to this point will be of little use until the
condition of arrangement of the full-grown plant is known.
Even those conditions frequently coming with the com-
pletion of the development, disturbing the original
arrangement, as forexample, the unilateral pushing together
of the leaves when there is unequal thickening of the
sides of the stem, the moving back of leaves by unequal
adhesion of the base, the apparent change of the arrange-
ment of the leaves from revolution of the stem, &c.,
require no great research into the rudimentary structure
to set them aside. Thus the method of determination
may be perfected, without directly tracing the first origin
of the leaves, to such a degree that the modes of arrange-
ment are almost everywhere to be arrived at, and a com-
parative investigation, carried out properly by means of the
method we possess, is capable of bringing Phyllotaxy to
such results, that it makes each individual case compre-
hensible in orderly connection with the entire system of
the arrangements of leaves. The true side of Schleiden’s
objection is, that this is not the final result, the final
establishment of Phyllotaxy, since for its completion we
necessarily require the elucidation of the connection of the
external arrangement of the leaves with the internal
arrangement of the cells in the apex of the stem, from
which the leaves emerge, and in which, simultaneously
with their origin, is laid the foundation of their
arrangement,—a problem toward the difficult solution of
which, the study of development has not yet made the
slightest step, at least in the realm of the Phanerogamia ;
moreover this also includes the explanation of the organic

REJUVENESCENCE IN NATURE. 121

processes in the cells themselves, through which their
arrangement is determined, as well as the forces with
which the organism works; in a word it includes at its
final point the Physics of Organization, 8f which botanical
science has at present scarcely a foreshadowing. There-
fore, everything at its proper time!

IIL.—CELL-FORMATION.

In proceeding to the subject of Cell-formation, we pass
over a series of phenomena of Rejuvenescence which
should be intercalated between the second and third
sections, namely, the processes of Rejuvenescence which
frequently occur in the development of the leaf itself, and
through which the leaf acquires its subdivision and com-
pound nature,—as well as the Rejuvenescence of growth
also occurring in the ulterior completion of the parts of
the leaf, of which we have spoken already in examining
the leaf ;* we farther pass over the phenomena of Reju-
venescence in the later completion of the stem, which
occur both in the longitudinal growth and the increase of
thickness, the former especially as intercalary growth of
the internodes,t the lateral as periodically renewed
growth of the cambium zone of the stem, between the
wood-mass and the bark, whereby originate the annual
rings in the trunks of the Coniferous and Dicotyledonous
trees. All these, as well as the already examined phe-
nomena of Rejuvenescence, necessarily lead finally to the
consideration of the cell, as the simplest sphere of
formation in the course of the life and growth of the
plant, from which ali development starts, which in infi-
nitely varied repetition and modification accompanies the
entire development, and to the independent representa-
tion of which the conclusion of the development once

* See page 113.
T See Grisebach, ‘ Ueber das Wachsthum der Vegetationsorgane,’ Wieg-
nmann’s ‘ Archiv,’ 1843, i, 267.

122 THE PHENOMENON OF

more returns. The investigation of each link, of each
organ of the plant, leads back to the simple cell: the
formation of the stem advances by division of a simple
apical cell;* thé formation of the leaf starts from a
single lateral cell in the vicinity of the apex of the stem ;+
every lateral sprout is originally a cell, which, instead of
remaining as a mere part of the tissue of the parent
sprout, becomes the primary cell of a new developmental
series.t To penetrate everywhere to these first rudiments
of structure, to follow out from them the course of deve-
lopment of the tissues of all parts, and to make out the laws
according to which the cell-formation progresses to pro-
duce the various arrangements on which the structure of
the plant essentially depends, is one of the most difficult,
but, at the same time, most profitable tasks, to the accom-
plishment of which Nägeli, in particular, has quite recently
opened the path by accurate and methodical description
of the history of the cell-formation and growth of numerous
plants belonging to the lower orders of the Vegetable
kingdom, from which alone the way can gradually be
levelled up to the higher.§

The investigation of cell-formation is no less necessary

* Definitely demonstrated in the Floridew, ve. g., in Polysiphonia and
Herposiphonia (Nageli, ‘ Zeitschrift,’ heft 3 and 4, p. 207, t. 6-8); Delesseria
hypoglossum (idem, heft 2, p. 121, t. 1); Laurencia (Nageli, ‘Die neueren
Algensysteme,’ t. 8, f. 4); Characex, Musci (Nägeli, ‘ Zeitschrift,’ heft 2,
p- 138, t. 4); Equisetacez (idem, heft 3 and 4, p. 167). If the apical cell
divides vertically into two equivalent. cells, consequently into two apical cells,
dichotomy results (see Dictyota, in Nigeli’s ‘Algensysteme,’ t. 5, figs. 12-16),
and by rapid repetition a fan-like expansion. Pechally the fasciation, as It
is termed, of the Phanerogmia, originates in this way.

T So at least in the Floridese, Characeze, and Mosses. (See Nägeliin the
already mentioned places.)

+ See the formation of branches of Zehinomitrion furcatum, in Nägeli’s
‘Zcitschr.,’ heft 2, p. 138, t. ii, figs. 1-6. Among the cases of which we have
an exact description, is also the origin of the seed-sprout or ovule of Orckis,
which, according to Hofmeister, (“Enstehung des Embryo der Phanerogamen,’
1849, p. 1, t. 1) is developed from a single cell of the placenta, which is
first divided into two superposed cells, the upper of which by subsequent
division forms the cellular coat, the lower the axial row of cells.

§ See the treatises relating to this in Nageli’s “Zeitschrift fur wiss.
Botanik.’ (1845-47), as also his ‘Kritik d. neuer. Algensysteme u. Versuch
eines eigenen Systems d. Algen und Florideen,’ 1547.

REJUVENESCENCE IN NATURE. 123

in physiological than in morphological respects; for to
the cell is committed all the vital activity of the plant ;
the material and form of the plant are produced in and
through it. In the cell resides the Wonderful power of
preparing the organic substances, which no other chemical
laboratory has the means of forming; in it the force of
endosmotic absorption and excretion, and that admirable
circulation, not yet physically explained, by which the
contents are, in the most varied manners, either imper-
ceptibly diffused, or driven in active currents; in it the
force of organic production of form and of growth, and,
finally, the force of transformation and reconstruction, on
which depend the multiplication and propagation of
plants. ‘The cell is, therefore, the immediate focus of
Rejuvenescence, the point from whence come all the
phenomena of Rejuvenescence in the building up of the
articulated (or complex) organism of the plant. Hence,
if we wish to become intimately acquainted with the
phenomenon of Rejuvenescence, we must search it out in
the cell itself. In the outset we distinguished two periods
in the process of Rejuvenescence, the period of retro-
gression, of solution and removal of the old, and the
movement of renewed progress, the repeated construction
and reformation; accordingly, after a prelimimary con-
sideration of the formation of the cell in general, we shall
examine the phenomena of Rejuvenescence in the life of
cells in detail,—in the Destruction (Entbildung), and
Reconstruction (Neubildung) of cells.

I.—FORMATION OF THE CELL.

Cell-formation is one of the most essential peculiarities,
one of the most constant characters of the plant. In
cell-formation, especially, the vegetable organism shows
itself to be determined in its formation from within ;
through this the plant cuts off its structure, as a whole,
as in the smallest subordinate sphere of life, from with-

124 THE PHENOMENON OF

out, interposing a boundary structure, the cell-membrane,
as a medium for the intercourse with the external world,
and a protection from direct attack. Although the plant
be developed almost infinitely through the unlimited
nature of the process of sprouting, its life appears in
every cell (with a few exceptions) as in a circumscribed
and in a peculiarly inwardly determined sphere of forma-
tion, so that the cell also is, in a certain sense, an indi-
vidual, and, in fact, has been pre-eminently regarded as
the individual of the plant by many authors.*

As the single plant begins with a simple cell, so does
the Vegetable kingdom. In the lowest stage of this the
plant presents itself as a simple cell, and the first repe-
tition of cell-formation is, at the same time, propagation.
The farther we trace up the stages of the Vegetable
kingdom from this point, the greater is the multiplicity
of the division of the originally simple sphere of life into
subordinate spheres, and the more frequently is the cell-
formation repeated: the vegetable organism becomes
multi-cellular. While the cell constitutes actually the
sole individual of the plant in Uni-cellular plants, in
the higher plants it becomes a sphere of formation sub-
ordinate to the more developed individual organism.
With the less perfect organisation of the plant, as com-
pared with that of the animal, with its peculiar deficiency
in a permanent and thoroughly pervading central relation
of the parts, the vegetable cell, as a subordinate part of
the organism, possesses a far greater individual independ-
ence than the cell of the animal tissue, manifoldly changed
in its structure, and more insolubly connected to the
whole.

Unicellular plants, in the strictest sense, are repre-
sented properly only by those in which the whole cycle
of life is completely shut up in one cell, the first recon-
struction or division being at once the commencement of

* Schleiden, “Grundriss der Bot.’ p. 28, and ‘Grundzüge,’ 11, p. 4.
U Principles of Se. Botany, London, 1819, p. 126.)

REJUVENESCENCE IN NATURE. 125

a new cycle; in which, consequently, the whole vegetative
life is run through in the same cell where the propagation
also finally appears. But in a wider sense, there are
other Unicellular plants, if, namely, we regard those as
one-celled, in which the conclusion and renovation of the
cycle by the formation of a germ does not occur until
after several generations of cells, yet the vegetative life is
passed through, not in a rigidly combined series of cells,
but in separate cells.* These cases are of two kinds.
In cases of one kind the vegetative life is really completely
shut up in one cell, but the formation of germ-cells in
this cell is attained, not directly, but through the medi-
ation of one or more transitory generations of cells.t
Such plants are truly Unicellular, as far as regards vege-
tation,{ since the transitory cells neither possess a special
and peculiar vegetative development, nor contribute to
the formation of a uniform vegetative tissue, but appear
only as a rapidly over-passed, transitional stage previous
to the formation of germ-cells,—as germ-cells, as it were,
which divide once or more times before they arrive at the
point from whence a new vegetative cycle can begin
again with germination.§ In the other cases the multipli-

* Unicellular plants occur in the series of Fungi and Alge, which have
very varied correspondence in morphological respects. In regard to the
latter I refer to Nageli’s most recent work (‘Gattungen einzelliger Algen,’
1849), in which is laid a new and solid foundation for the knowledge of these

lants, so interesting in this respect, but hitherto (with the exception of the
Diatomacese and Desmidiacez), from want of observation on the development,
only most superficially known, and heaped together in the most chaotic
manner in the Systems of Alge.
Vide Nagel, ‘Einzelliger Algen,’ p. 28.

In systematic respects, also, the unicellular genera are most closely
Gene. since many genera with transitory cell-formation in the passage
to spore-formation exhibit great agreement with those without this (except-
ing in this one character). Thus Cystococcus, Nag. (I. c., p. 84, t. 3, E),
with transitory cell-formation, corresponds with the genus Protococcus (as
limited by Nägeli), with immediate or simultaneous spore-formation ; Chara-
cium, A. Br. (Näg., 1. c., p. 86, t.3,D), perfectly corresponds to the genus
Ascidium, A. Br.; Pediastrum, Meyen, in many respects to the genus
Hydrodietyon, Roth.

§ This case is repeated in multicellular Alge, Ulothrix, Ulva, Porphyra,
(Nag. ‘Algensyst.,’ t. 1, f. 61, 62), Hetocarpus, (ibid., t. 2, figs. 3, 4, 5);
similar cases occur even among the Fucoides, since, according to Decaisne

126 THE PHENOMENON OF

cation of the cell happens in the vegetative sphere, the
cells increase in number by a succession of divisions
before the vegetative cycle closes with fructification ; but
the plant is incapable of keeping intimately connected the
generations of cells thus produced, of building: forth the
organism as a whole, in these divisions; it breaks up
more or less completely into the individual cells, which
thus, although members of a definite cycle of vege-
tation, lead a separate individual life. We see that
which is completed by the higher plants in an orga-
nically connected series of cells, represented here by
an alternation of generations of unicellular vegetable
individuals.* It is therefore impossible to draw a
strict line between Unicellular and Multicellular plants
in this respect, since there exist numerous intermediate
stages leading from the most intimate union to total
separation.

The completion of the contrast of growth and dif-
ferentiation of the organs does not always keep pace with
the simplicity or complexity of the tissue. Even among
the Unicellular Algze, most strictly so called, we find the
general opposition of growth of the plant expressed more
or less distinctly m the unicellular individual; in fact
we find that the very fundamental organs of the plant,
stem, leaf, and root may be represented with more or
less evident distinctness by parts of one and the same
cell. The graduated succession which we detect, in this
respect, among the Unicellular Algze, is so well adapted
to enlarge the ordinary conception of the cell, that we
cannot omit a brief examination of it here.

The simplest condition of the unicellular plant would

and Thuret, the originally simple spore of Fucus canaliculatus breaks up
into two, that of F. zodosus into four, of F. serratus and vesiculosus (doubt-
less by repetition of division) into eight spores. (Vide Decaisne and Thuret,
‘Sur tee Anthéridies et les Spores = quelques Fucus,’ ‘Ann. des Sc. nat.,’
1845.

* Here refer the Diatomace&, Desmidiacex, and most of the Palmellacex.
For the course of the generations of the first, see Thwaites ‘ Further Observa-
tions on the Diatomaces,’ (‘Ann. and Mag. of Nat. Hist.? 1848, sec.
ser. i, 161.) =

REJUVENESCENCE IN NATURE. 127

be, when the cell exhibited no other difference of its
sides and parts beyond the contrast of contents and
membrane, therefore was completely uniform over its
whole periphery. According to the description Nägeli
gives of his family Protococcacese, Protococcus* may be
regarded as the representative of this stage, being a
genus of which the individuals are globular cells, pro-
ducing free, likewise globular germ-cells, in their contents,
after their vegetative growth is completed. But it
appears to me doubtful whether, strictly speaking, such a
condition of the cell, completely equal in its relations to
all sides, ever occurs. If Protococcus, as is probable,
possesses moving (swarming) germ-cells, these cells will
doubtless be found to exhibit, in the moving stage, an
elongation, so as to have a principal axis, and two
different extremities, one of which bears the cilia, while
the coloured contents of the cell are crowded into the
other. In Hydrodictyon, which genus must likewise be
included in the family of Protococcacez, the cells, con-
nected into a net-like colony, have also a distinct longi-
tudinal extension in their ulterior development, without,
however, any difference in the two ends, since the
extremities are both joined in a similar manner to the ends
of the adjacent sister-individuals to form the network.
But a distinct contrast between the upper and lower end
of the cell presents itself in the same family, in the genus
Ascidium, the free cells of which attach themselves to
foreign objects by one end (that elongated and bearing
the cilia at the period of swarming), whilst the free
extremity (originally the more obtuse) becomes prolonged
into a short point. In the tubular cavity of the cell, the
contents form a coating over the inside of the wall, by a
simultaneous division of which, after the vegetative
developmentis completed, numerous germ-cells are formed,
finally swarming out of the expanding mother tube,

* According to Nageli’s limitation of this chaotic genus. (Vide Nägeli,
‘Die neueren Algensysteme,’ p. 153.)

128 THE PHENOMENON OF

which becomes torn at the side or bottom.* The con-
trast in the development of the upper and lower ends
of the cell presents itself still more strikingly in Boéry-
dium. The young plant is a globular cell, which might
be readily mistaken for a Protococcus, but, with further
development, a hyaline prolongation is produced below,
penetrating into the earth and branching like a root,
while the upper part of the cell swells up more and more
into a large obovate vesicle. The mucilaginous contents
form a lining to the walls, containing numerous chloro-
phyll vesicles. After the growth is complete, numerous
germ-cells are formed out of the lining coat of the wall,
and these do not appear to swarm, but are set free by the
membrane of the parent-cell becoming gelatinously
softened, collapsing, and finally dissolving. In Vaucheria
the lower part of the cell grows out in like manner into
a branched pale-coloured root, and the upper part is
elongated in a still more considerable degree into a
stem-like filament, which grows on and on by apical
development until its growth is finally arrested by fruc-
tification. From the ascending filament arise lateral
prolapsing branches, endowed with special faculty of
apical growth, some of these being large and erect like the
main stem, others small and divergent. A single moving
germ-cell is produced in the point of each erect branch ;

* Ascidium acuminatum, A. Br., occurs near Freiburg, in waterbuts or
troughs, or on stones or conferve in rills flowing from springs. It resembles
in aspect Characium Sieboldii, A. Br., occurring in similar situations, from
which it is easily distinguished by the more bulging form of the cell, more
apiculated at the apex, and never containing more than one starch-vesicle.
The swarming germ-cells are syth — y;th of a millim. long, longish, and
furnished with two cilia at the narrower end, 13 to 2 times as long as the
germ-cell. After the germ-cell has settled down by the ciliated end, the
plant grows rapidly, is at first slender and attenuated upwards and down-
wards; subsequently it becomes bellicd out, almost ovate, running out
suddenly into asharp point above. The full-grown cell is about , millim.
long. While young, the cell is filled up uniformly with green contents,
later they form a rather thick coat over the wall, uneven on the inner free
surface. When the formation of germ-cells commences the starch-vesicle
pee and the coat lining the wall becomes subdivided into 50 — 60
gonidia.

REJUVENESCENCE IN NATURE. 129

in the horizontal branchlets are formed, in each case, one
thick-coated, resting spore.* Bryopsis goes still further
than Vaucheria in the development of different parts
from one and the same cell; for in this the cell
produces roots on one side, and, on the other, erect
stems, with apical growth, multiplying themselves by
ramification. On these stems are formed distichous, or
spiral series of shorter branchlets, with limited apical
growth, these clothing the stem like leaves, and finally,
when the canal of communication with the stem has
become closed up, falling off like leaves. ‘The numerous
moving germ-cells of Bryopsist are formed in these
branchlets. The genus Caulerpat forms the last link in
this series of remarkable shapings of the simple cell.
In this the undivided cell forms in its development a
creeping stem, growing on ad infinitum at its apex,
from which (besides inessential branches, repeating the
main stem, and, like it, unlimited,) proceed two kinds of
branches with limited growth, different from each other
and from the main stem, namely, to the under side
divided roots, to the upper leaf-like branches which,
originally cylindrical, expand into laminz in subsequent
growth, and present different forms according to the
species ; in Caulerpa prolifera, for example, lingulate and
obtuse, in C. denticulata§ broadly lanceolate, deeply
toothed, and somewhat acute, in C. plumaris pinnatifid
or cut like a comb. Much as these structures remind us,
by their form, of the stem-leaves of the higher plants,
they are merely hollow prolongations of the one cell,

* Vaucheria, moreover, passes into a many-celled condition in the pre-
paration for spore-formation, for the points of the branches on which spore-
formation occurs, become shut off into distinct cells. Vide Unger, ‘ Die
Pflanze in momente der Thierwerdung,’ (1843), and Thuret, ‘Sur les Organes
locomoteurs des Spores des Algues,’ (‘Ann. des Sc. nat.,’ 1843.)

} Vide the section on Bryopsis, in Nägeli, (‘Algensysteme,’ p. 171;)
‘On the Formation of Spores,’ J. Agardh, (‘Ann. des Sc. nat.,’ 1836.)

+ Vide Nageli’s important researches in Caulerpa prolifera, (‘ Zeitschr.
fur Wiss. Bot.’) heft 1, (1844,) p. 134.

$ Decaisne, ‘Plantes de l’Arabie heureuse,’ ‘Arch. du Mus.’ ii, (1839,)
t. vi, B

9

130 THE PHENOMENON OF

which developes itself into the form of stem, root, and
leaf. ‘The origin of organs of distinct kinds, which is
connected in the higher plants with a very complicated
multiplicity in the cell-formation, appears here to be
attained simply by development of one and the same cell,
separating itself into different directions of growth.

The simplest plants with a many-celled cycle of vegeta-
tion, whether this be connected or broken up into con-
stituent members, stand far behind the plants with a
unicellular cycle last considered, in regard to organic
differentiation. In this series again, nature ascends by a
scale of different types, from a minimum of contrast in
growth, to a progressively more distinct realization of the
various directions of formation. That which was attained
in the former cases through the differentiation of the
individual cell, without isolation of its parts one from
another, is here reached in the most manifold gradations
through the formation of cells differing among themselves,
this happening either merely by a difference in the gene-
rations of cells, or by a different character of the cells of
the same generation. The distinctions occurring here
may relate either to the mode of origin of the cells
(combined or free formation), to the generative capability
(permanent cells and mother-cells), or to the mode of final
development (predominant growth in one or other direc-
tion, the different shaping of the contents and of the walls).
Thus arises an infinite variety in the genealogy, arrange-
ment and final development of cells, which becomes the
more difficult to trace the higher we ascend in the vege-
table kingdom. I confine myself to a few indications
from the lower groups of the vegetable kingdom, especially
from the Alge, the deep study of which appears the more
important the more fully the science becomes conscious
of its object—to penetrate into the regulated course of
development of vegetable structures in all their infinite
complications.

The simplest conditions are exhibited by those plants
in which all the generations of cells, except the transition-

REJUVENESCENCE IN NATURE. 131

generation leading from one generation-cycle to another,
are alike. As long as mere vegetative multiplication
lasts, similar generations are formed; with the commence-
ment of fructification is formed a last generation of cells,
different from the preceding, constituting at the same
time the first generation of the new cycle, and as such,
although originally different, exhibiting in its final develop-
ment the same characters as the succeeding vegetative
generations. The last generation (that of the germ-cells
or spores,) is either imperceptibly or perceptibly different
from the foregoing, which circumstance gives room for
a series of subordinate gradations. Among the instances of
the former condition are the Chroococcacex,* to which are
allied (with more intimate connection of the vegetative
generations of cells) the Oscillariex, and a part of the
Palmellacese,t to which are related the Hormidia,t with
Prasiola. In all these the propagative cells agree with
the vegetative in their origin, and are only distinguished
from them by the circumstance of becoming free at last,
while the vegetative cells of all or at least of several
immediately succeeding generations remain combined

* Vide Nageli, ‘Einzellige Algen,’ p.44,t.1. In Synechococcus, Glaothece
and <Aphanothece the cells of all the generations become elongated and
divided in the same direction, and would, if they did not separate from each
other, form filaments, like Oscil/aria; in Merismopedia the generations are
divided alternately in two directions of a plane, whence flat, single-layered
plates are formed; in Chroococeus, Gleocapsa, and Aphanocapsa the division
takes place alternately in three directions of space, whence arise globular or
finally shapeless families. Directing our attention to the difference in the
position of the axes and the planes of section of the cells, in the last-named
cases, we may distinguish in the succession of the otherwise similar genera-
tions, subordinate cycles, in one case with two members, in the others with
three. There is also another respect in which the succeeding generations
are not always exactly alike, the last generations frequently remaining smaller
than the earlier, as, for example, is ordinarily the case in Gleocapsa, where
the size of the cells diminishes with the increasing magnitude of the family-
stock (phytodom).

{ Be. gr. Stichococcus, (Näg., 1. c., t. iii, 6); Hormospora, (Nag., t. ili, B) ;
Pleurococeus, (Näg., t. iv, E); Gleocystis, (Näg., t. iv, F); Palmella, (Nag.,
t. iv, D); Porphyridium (Nag.,t. iv, H); the first two forming rows of cells,
the last four solid groups of cells.

t In the genuine Hormidia, not living in water, I have found no other
propagation but a breaking up of the filaments into single cells. Hence
Hormidium seems to me most closely allied to Stichococcus and Hormospora.

132 THE PHENOMENON OF

in families, either loosely (by thin or gelatinous enveloping
membranes), or more firmly (by tougher cell-coats). ‘The
second case, in which the reproductive cells show impor-
tant differences from the vegetative generations, is repre-
sented by a few Palmellacee with swarming transitional
generations, and by the Diatomaceze. In the former the
reproductive cells originate, like their predecessors, by
division, but they soon assume a peculiar form and, fur-
nished with cilia, break through the enveloping membrane
of the old family to commence the vegetative cycle anew,
after a short period of motion;* in the latter, the
Diatomacez, the transitional generation is formed in a
way essentially different from the preceding division-
generations, for two cells become connected by simple
or double conjugation, and, form one or two reproductive
cells by the combination of their contents at the point of
connection ; these reproductive cells are originally globular
and altogether unlike the very peculiarly shaped vegeta-
tive cells of this family, but, by an uninterrupted growth,
soon acquire the shape of the parent-cells, from which
the first generation of the new cycle originating in this
way is distinguished merely by greater size.t

* Vide the genera Tetraspora, (Nag., t. ii, c); Dictyospherium, (Näg.,
t. il, 8); Apsoeystis, (Näg., t. ii, A); the first of which forms a cellular
late, the second a free solid group of cells, the third a solid group attached
I an altenuated base like astalk. Besides the alternation in the direction
of the divisions, there occurs in these genera a further slight distinction in
the generation of cells, in that one or two generations of nll are alternately
transitory, that is, they divide anew before they have attained the usual size
of the vegetative cells.

f Vide Thwaite’s ‘Observations on the Diatomacee,’ ‘Ann. and Mag. of
Nat. Hist.,’ vol. xx, (1847,) t.iv; (Zunotia turgida), t. xxii; (Cocconema
lanceolatum, Gomphonema minutissimum Himantidium pectinale), series 2,
vol. i, (1848,) t. xi, (Melosira and Cyclotella.) The denomination of the
reproduction cells produced through conjugation as sporangia (sporangial
frustules) by Thwaites, depends on a too widely stretched comparison with
those of the Desmidiacex. According to Thwaites’s own description, the
reproductive cells of the Diatomacee pass directly into vegetative cells,
which is not the case in the Desmidiacee. The strange phenomenon that
the primary generation formed through the conjugation attains about double
the size of the parent cells, is simply explained by a gradual decrease of size
in the series of vegetative gencrations formed by division, a phenomenon to
which I have already called attention above in the case of Gleocapsa.

REJUVENESCENCE IN NATURE. 133

In the cases hitherto examined we could observe, in
the series of successive generations of cells, only one
different from the rest, the transitional generation, which
is at once the last of the old and the first of the new
cycle of generations. In the Desmidiacex, the Zygne-
maces, and in Palmoglea, the transitional generation
is divided into a double one, since the last generation
does not pass directly into the first, but the first
generation of the succeeding cycle is produced, as a
new structure, in the germination; so that we have
here to distinguish three kinds of generation of
cells,—the commencing generation, the concluding
generation, and the intermediate vegetative generations.
In the Desmidiacez, after a long series of vegetative
generations of cells, which sometimes remain connected
in rows (Desmidium, Didymoprium, Hyalotheca), some-
times vegetate as completely separate cells (Micrasterias,
Euastrum, Closterium, &c.), there occurs a conjugation of
two cells and union of their contents in the point of
connection, whence is formed one,* or, more rarely (by
double conjugation), two} reproductive cells, wholly
different from the preceding vegetative generations in the
form and aspect of the cells. They are always globular
and thick-coated, sometimes smooth,} sometimes rough,
like the ancient spiked mace-heads, with simple or many-
pointed, forked or hooked spines;$ and they do not
pass, like the swarming-cells of the Palmellacee and
the reproductive cells of the Diatomacez, directly and by
uninterrupted growth into the primary generation of the
new vegetative series, but persist for a long time in a
condition of rest, during which, excepting as regards

* Vide the illustrations in Ralfs’ excellent Monograph of the British
Desmidiacee, (London, 1848), for instance, t. iii, (Didymoprium) ; t. xvi,
(Cosmarium) ; t. xxiv, (Tetmemorus) ; t. xxv, (Penium);, t. xxvi, (Docidium) ;
t. xxvii, xxviii, (Closterium); also Nageli, ‘Einzell. Algen.,’ t. vii, f. 6,
(Cosmarium rupestre).

Ralfs, 1. c., t. xxx, (Closterium lineatum).
£ Ralfs, 1. e.,t. iv, (Desmidium) ; t. xxv, (Penium) ; t. xxix, (Closterium), &c.

§ Ralfs, Lc., t. vii, (Mierasterias) ; t. xii, (Euastrum) ; t. xvi, (Cosmartum) ;
t. xxil, (Phycastrum), &e.

134 {HE PUENOMENON OF

imperceptible internal processes, they remain wholly
unchanged.

To distinguish these from the direct germ-cells ( gonidia),
I shall call them seed-cells (spores).* The development
of these spores has not yet been observed, but it may be
assumed as certain that they do not pass, as such, into
the primary generation, but produce this at the period
of germination by an internal transformation of their
coutents, and bring these to light as a new generation,
with a dehiscence of the old envelope. Certain early
conditions observed in Closterium and Euastrum, namely,
families of unusually small individuals, enclosed in
transparent, colourless vesicles,f render it even probable
that m certain genera of this family, a number of indi-
viduals are produced from one spore, by a formation of
transitory generations occurring already within the spore.
The enclosing vesicle is probably the dissolved and
swollen-up internal cell-coat of the spore, which holds
the young individuals combined for some time after the
outer coat of the spore has been thrown off. The be-
haviour of the spores of the family of the Zygnemacee,
which appears to be closely allied to that of the Desmi-
diacez, confirms the conjecture as to the development of
the spores of the latter. The filaments of the Zygnemacex
are composed, like those of the Desmidiacez with con-
nected cell-generations, merely of one kind of vegetative
cells, which increase by repeated halving.t The last

* Many authors call these cells sporangia; but if we compare their
behaviour with that of the spores of the higher orders of Cryptogamia, in
which, in like manner, only the internal substance is developed into the
germ-plant, the coat being thrown aside, we must regard them as true
spores, while, on the other hand, those spores of the Alge passing directly
into germination, to which belong in particular all swarming-spores, differ
importantly from ordinary spores, and would be better termed Gonidia.

+ ara lc. t. xxvii, and Focke, ‘Physiologische Studien,’ (1847,)
t. iil, fig. 27.

} So far as my observations extend, the filaments of the Zygnemacex
appear, like those of Desmidium, to be formed merely by repeated division
into equivalent cells, thus to possess neither apical growth nor distinction
into an upper and lower end. I have never found the radical structure by
which they are often attached otherwise than lateral. Unfortunately I

REJUVENESCENCE IN NATURE. 135

cells originating in this way are ordinarily shorter than
those of the earlier generations, and enter into conju-
gation* in the well-known way, subject to many
modifications. ‘Through the union of the contents of the
two conjugated cells, is formed, either in one of the two
cells, or in the link connecting them, a globular or longish
smooth spore, clothed with a multiple coat, from which
the young plant is developed after a long stage of rest.
In Spirogyra the coats of the seed-cell (spore) are thus
torn,—first the outer, thinner, water-clear coat, next the
inner, thicker, yellowish spore-coat is stripped off, and
the contents, transformed into the germ-cell and clothed
with a new coat, emerge in the form of a spindle-shaped
body, having both ends of like character,f which bears
great resemblance to the solitarily living cells of the
Desmidiaceous genus Spirotenia.t But the observations
of Thwaites, who saw the contents of the ripe spore
separate into four portions in certain Zygnemaces, par-
ticularly: Mesocarpus and Staurocarpus,§ testify that a
formation of several germ-cells or young plants in one
spore may occur in this family.

Essentially different from the conditions of the
Desinidiacee and Zygnemaceze is the propagation of
Palmoglea, a genus which has hitherto been reckoned
among the Palmellaceze, to which, although the occur-
rence of a conjugation of the cells might incline one to the
opposite view, it is certainly more intimately related

have not been able to follow the observation of the germinating plant as far
as the commencement of root-formation. (See Pringsheim, on Spirogyra,
‘Flora,’ 1852; Transl. in ‘Annals of Nat. Hist.,’ 2d ser., vol. xi, 210.—A. H.)

* Vide Hassall, ‘ British Fresh-water Alga,’ (1845) t. xvii—xlix.

{ The germination of the Spirogyre was observed by Vaucher (‘ Hist.
des Conferves d’eau douce,’ 1803). I have seen it take place in the above-
described way in July of the present year, in Spirogyra retiformis, which had
been collected with ripe spores eleven montlis previously. I shall mention
hereafter some of the remarkable changes in the contents of the spores
occurring as preparatory to germination, (See Pringsheim, l. c.—A. H.)

+ Vide Ralfs, 1. e., t. xxxiv, f. 1, 2.

§ Iam only acquainted with these observations from- the report in the
‘Botanische Zeitung,’ 1846, p. 498. (‘Ann. Nat. Hist.,’ xvii, 262. See on
this subject also Pringsheim on Spirogyra, 1. v., p. 296.—A. H.)

136 HE PHENOMENON OF

than to the Desmidiacex. While, in the Desmidiacez
and Zygnemacee, the last generation of vegetative cells
produces the seed-cells (spores) as a new generation,
since the latter shape themselves out free in the interior
of the conjugated pareut-cells, through the loosening of
the contents of the latter from the walls,—in Palmoglea
the last vegetative generation passes directly into the
formation of seed-cells (spores), since the cells combining
in pairs by conjugation, enter into perfect union, 2. e.,
not merely mix their contents in a new structure, but
merge or flow one into another entirely (coat and con-
tents) like two drops of water. The large seed-cells
(spores) originating in this way gradually acquire a thick
coat and oily contents, passing into a summer-sleep,
overlasting the hot and dry season, till, with the recur-
rence of the cold damp season, the contents become
metamorphosed and divided, while the coat of the seed-
cell swells up and dissolves into jelly. Thus the primary
vegetative generation is produced as a new generation
out of the seed-cell, the contents first formed by blending,
dividing again, and becoming freed from the coat of the
mother-cell.*

So far as we have hitherto examined the differentiation
connected with the succession of generations of the cells,
we have found solely like cells within each generation ;
we have seen, moreover, all the terminal links of the
multiplied series attain the conclusion of the cycle (as
fructification-cells) in the same way, accidental exceptions
being of course excluded. The further complications
arise not only from a greater difference presenting itself
in the successive generations, but from the cells of the
same generation also exhibiting different characters.
The latter, again, may happen in two ways: either two
daughter-cells originating in one and the same mother-
cell (therefore two sister-cells) are unlike each other,
or the daughter-cells of distinct mother-cells belonging to

* Vide the figures in Pl. 1, and the more minute description of Palmoglea
in the Appendix.

REJUVENESCENCE IN NATURE. 137

the same generation (that is the first-cousin-cells) differ
from each other. The first condition is of especial im-
portance in regard to the development of the organic
differences in vegetative structure, since on it depends
the apical growth and the ramification of many-celled
plants; on the latter depends, among other things, a
duplicity of fructification, occurring even in the lowest
groups of the Vegetable kingdom, and which we shall
here, in the first place, briefly examine. Numerous
Alge produce two (or sometimes even three) kinds of
reproductive cells, either two kinds of moving or motion-
less gonidia, or gonidia and spores, or, lastly, two kinds
of spores, which last can also occur in the higher groups
of the Cryptogamia. Probably this phenomenon is more
generally diffused among the Algze than can be accurately
demonstrated at present ; therefore when I mention many
doubtful cases here, it is with the express purpose of
directing attention to an object deserving of further
investigation.

Among the examples of plants with two kinds of moving
germ-cells, large (macrogonidia) and small (microgonidia)
the Water-net (Hydrodictyon) already mentioned above,
is especially worthy of mention. The unicellular indi-
viduals of this Alga, hitherto incorrectly arranged with
the Zygnemacez,* are united in their earliest stages into a
colony, forming a bag-shaped net. All the cells of such a
net are sister-cells, for they all originate in one and the
same mother-cell, but they do not all behave alike when
fructification commences. In certain cells are formed
somewhat larger and less numerous gonidia (according to
the size of the mother-cell, 7000 to 20,000), in other cells
of the same net somewhat smaller and more numerous
gonidia (30,000 to 100,000). Only the former (the
macrogonidia) forma new net, which they do after a short
tremulous movement (lasting about half an hour), without
leaving the mother-cell, by uniting together into a
daughter-net, which is gradually set free by the solution of

* Kützing, ‘Species Algarum’ (1849), p. 448.

138 THE PHENOMENON OF

the coat of the mother-cell. The microgonidia, on the
other hand, distinguished not only by their smaller size
but by a longer shape, a small parietal red vesicle and
four long cilia (which appear to be very short in the net
forming macrogonidia), swarm out from the bursting
mother-cells, move about very actively, often for the
space of three hours, and after coming to rest, become
green Protococcus-like globules, which vegetate for some
time and at length die away without any further pro-
pagation. ‘Thus we see here formed in previously
indistinguishable sister-cells of the same net, brood-cells
of two kinds, which are both direct germ-cells or gonidia,
but are developed one into a fertile generation, the other
into a sterile generation fated to destruction ; both active,
but in different degrees, one, moving for a short time,
forming a net, the others, ‘‘swarmers,”’ never reunited
into acolony.* Two kinds of active germ-cells, (macro-
gonidia and microgonidia, occur also in Chlamidococcus
pluvialis (Hematococcus pluvialis, Flotowt) a plant allied
to Chlumidomonas and the Volvocinee, into the compli-
cated history of which, however, I cannot enter further
here, lest I should be led away too far into the debateable
ground between the Animal and Vegetable kingdoms,
Another example, belonging to the group of the filiform
and branched fresh-water Algze, is furnished by Drapar-
naldia, from which Stigeoclonium is scarcely generically
distinct. Draparnaldia mutabilis, the numerous species
of Stigeoclonium, as well as the very nearly related
Chetophore, are among those plants in which the for-
mation and birth of active germ-cells may be most
easily observed, and indeed have very frequently been

* I must reserve the history of this remarkable plant, to which I shall
return several times, for another opportunity. My own observations were
chiefly made in the summer of 1846, and the results made known at the
meeting of the Swiss “ Naturforschende Gesellschaft,” at Schaifhausen, in
August, 1847.

+ ‘Nova Act. Nat. Cur,,’ vol. xx, ii, 1844. (Also Colm, ‘Nova Acta,’
xxii, p. 397, an abstract of which paper is included in this volume. Also
Schacht, ‘Die Pfanzenzelle,” Berlin, 1852, p. 124.—A. H.)

REJUVENESCENCE IN NATURE. 139

examined.* In the three genera named there is formed,
in each cell of the branches, after their last vegetative
division, an active germ-cell, which, furnished with four
cilia and a parietal red vesicle, breaks through the side
of the cell-wall in swarming out. In Stigeoclonium
‚protensum, K. (?), however, I have found, towards the
end of the period in which this plant appears, a modifi-
cation of the mode of formation of the active gonidia,
in which each cell gave birth not to one, but (by per-
pendicular division of the contents) two to four smaller,
more roundish swarmers; as to the germinative powers
of which, however, I have no experience. In Draparnaldia
mutabilis, also, I observed an analogous formation of
microgonidia, not produced by perpendicular, but by
further continued horizontal division of the cells.
Nägelif mentions an observation on Melosira varians,
according to which the parietal colour-vesicles of this
Diatomacean sometimes become detached, and move in
the manner of swarm-cells, which might indicate an
occurrence of active microgonidia, together with the above-
described formation of larger, motionless germ-cells.
Many examples may be cited of the conjoined occurrence
of gonidia and true spores; many of these, however,
still require more accurate investigation. In the family
just named, the Diatomacez, certain genera seem to
exhibit, as a second mode of reproduction, a formation of
seed-cells with numerous young individuals, such as we
have assumed above of Closterium; so also Schizonema and
Micromega.} In the Desmidiacex, on the contrary, a

* Vide Treviranus, ‘ Vern. Schriften,’ ii, 1, p. 73 (1817—Draparnaldia) ;
Kiitzing “über die Verwandlung der Infusorien in niedere Algen-formen’
(1844—Stigeoclonium stellare); Fresenius, ‘Zur Coutroverse über die Ver-
wandlung von Infusorien in Algen’ (1847—Chetophora). I have myself
observed the active germ-cells of Draparnaldia mutabilis, Stigevelonium
thermale (June 1847), subspinosum (May 1847), protensum? (May 1848),
tenue (July 1849), Chetophora tuberculata (Aug. 1847), and elegans (Sept.
1847).

+ Vide Nägeli, ‘Gatt. einzelliger Algen,’ p. 10.

+ Vide Kützing, ‘die Kieselschaligen Bacillarien oder Diatomaceen’
(1844), t. xxv, f. 8; t. xxvii, ££ 11; t. xxvii, f. 1.

140 THE PHENOMENON OF

formation of gonidia seems to occur sometimes together
with the spore-formation, and this in a double way. ‘The
formation of numerous small swarmers in unconjugated
cells is mentioned by Ralfs as a not uncommon phe-
nomenon, but in so indistinct a way, that we cannot form
a satisfactory idea of it.*

The active corpuscles found by Ehrenberg in a
Closterium, which he described as monad-like Infusorial
animalcules, under the name of Bodo viridis,t might be
referred here.

According to Morren,{ there is a totally different
process in Closterium Lunula, where, through conjugation
of two individuals, a single large active germ-cell is
formed, which commences a revolving movement in the
connecting canal of the parent-cell, already inside the
coats, then leaves the torn coats, and, after swarming
from ten to twenty minutes, sinks down and immediately
germinates, 7. e., becomes elongated and returns to the
form of the old Closterium.

If these statements of Morren are correct, there occurs
in the Closterta a double character of the reproductive cells
formed through conjugation, these sometimes appearing
as direct germ-cells (gonidia), and sometimes as true seed-
cells, it being uncertain whether the two cases occur in
one and the same species, or separately in different
species.§ The two-fold fructification of Vaucheria has
been spoken of already above (p. 128) ; it follows also,
from the observations of J. Agardh,|| that large spores
are formed in addition to the small gonidia in Bryopsis.
Moreover, the simultaneous occurrence of gonidia and
spores is beyond doubt, in the large genus Zdogonium

* Ralfs, ‘the British Desmidiew, p. 9.

+ Ehrenberg, ‘ Infusionsthierchen,’ t. ii, f. 15.

} Morren, ‘Mémoire sur les Closteries.’ (‘Ann. des Sc. nat.,’ v, 1836.)
(See also Smith, ‘Ann. Nat. Hist.,’ 2d ser., vol. v, 1.—A. H.)

\ It is remarkable that Ralfs, who has seen the formation of spores in so
many Desmidiaces, says nothing about it in reference to this very Closterium
Lunula, and the allicd species (7. Ehrenbergii and moniliferum,

|| J. Agardh, ‘Algee maris mediterranei’ (1842), p. 4:

REJUVENESCENCE IN NATURE. 141

and the allied genus Bulbochete, in which particular
cells, in Zdogonium those of the unbranched filament, in
Bulbochete those of the branches, swell up and produce
within a motionless seed-cell, acquiring a special mem-
brane, often quite removed from the membrane of the
mother-cell, and destined to a long stage of sleep, while
the contents of the rest of the cells, when otherwise
sufficiently abundant in quantity, become converted into
an active germ-cell, bearing a crown of numerous cilia.
In Gdogonium the birth of the swarming-cell takes place
through a transverse dehiscence of the parent-cell at the
anterior end; in Bulbochete by disarticulation of the
small cell bearing the bristle, and rupture of the wall
separating it from that of the large cell.* Certain species
of Edogonium (Gi. echinospermum and apophysatum) are
especially remarkable, since they produce, in addition,
two kinds of swarming cells, macrogonidia and microgo-
nidia, the latter of which originate in special, very short
cells, arranged mostly in groups between the larger
cells. The macrogonidia germinate as soon as they come
to rest, and grow up into normal filaments; but the
microgonidia, although they germinate, produce only
two-celled dwarfs, which die away without developing any
further. The genus Coleochetet affords another example
of the united occurrence of gonidia and spores. Indi-
vidual terminal cells of this genus are developed into

* In Gdogonium fonticola A. Br. (‘ Kg. Sp. Alg.,’ p. 368), a species which
occurs almost everywhere in the pools formed by running springs, the forma-
tion of the “swarmers” may be observed throughout the whole year, while
the formation of the resting spores occurs but rarely. In &. capillare,
the commonest species of the genus, I have hitherto met with “swarmers”
alone. I have observed both kinds of fructification in @. Landsboroughii
(Hass.), vesicatum (Vauch.), fasciatum (Hass.), Braunii, Kg., echinospermum,
A. Br. (Kg. 1. c. 366), apophysatum, A. Br. (ibid.), Bulbochete setigera, Ag.,
and minor, A. Br. (Kg. l.c. 422). Cymatonema confervaceum, Kg. (Sp. Alg.
375), behaves exactly like @dogonium in the bursting of the cells, but I have
not yet succeeded in observing the swarming out. (See also Thuret,
‘ Zoospores des Algues,’ Ann. des Sc. nat., 3d ser., xiv, p. 17, pl. 19.—A.H.)

+ Vide Nägeli, ‘ Algensysteme,’ p. 166, v, f. 22—31. I have observed
the formation of spores, as well as of gonidia, in both species of this genus,
C. scutata, Brib., and pulvinuta, A. Br. (Kg. ‘Sp. Alg.,’ 424).

142 THE PHENOMENON OF

sporangia, in which several resting spores are formed by
division of the coat lining the wall, while the contents of
the rest of the cells are frequently converted into a
gonidium, which in C. seutata breaks through the upper
wall of the cell, and in C. pulvinata emerges laterally, to
swarm. ‘The gonidia of this genus appear to possess
only two cilia. In the marine Algz of the genera
Mesoglea* and Myrionema, a double, in Letocarpust
a triple, fructification has been observed ; but it is very
doubtful whether large resting spores occur in these
genera, besides active gonidia, since Nägeli has pointed
out that in Zetocarpus the contents divide into numerous
small germ-cells, not only in the roundish apical cells of
the branches, but in the longish, many-celled points of
the branches, and in the expanding articulation cells of
the stem. On the other hand, in the Fucoidez, (in the
strictest sense,) the occurrence of large resting-cells,
together with very small swarming-cells, regarded by
Decaisne and Thuret{ as spermatozoids, is beyond doubt.
Both kinds of fructification are formed, in the Fucoidez,
in the terminal cells of the jointed filaments which clothe
the interior of the fructification cavities. The extremely
small gonidia are of pale colour, and have a parietal red
point. According to the authors cited, they exhibit two
extremely delicate filaments, one in front vibratile, the
other, behind, said to be passively swayed about.§ The

* Kiitzing, ‘Phyc. generalis,’ t. xxvii, 1.

+ Vide Crouan (‘Ann. des Sc. nat.,’ 1839, p. 248, t. v); and Nägeli,
‘ Algensysteme,’ p. 145, t. 11, f. 1—6. (Alse Thuret, ‘Ann. des Se. nat.,’
3 ser., xiv, p. 25, pl. 24.—A. H.)

+ Decaisne et Thuret, ‘Recherches sur les Antheridies et spores des
Fucus,’ (‘ Ann. des Sc. nat. i, iii, 1845,) t. iii.

§ The position of the cilia is thus importantly different from that usual in
the active gonidia of the fresh-water Alge ; on the other hand, the swarming-
cells of the Fucoidex do not agree at all in form with the spermatozoids
such as we are acquainted with in the Characex, Mosses, and Ferns.
Whether, like the spermatozoids, they are formed in special, minute cellules,
or originate by simple division of the contents of the large parent cells, is
unfortunately unknown. The character of the contents of the “ swarmers”
of the Fucoider renders it unlikely that they possess the power of germi-
nating, but it cannot be deduced from this that they havea fertilising action.

REJUVENESCENCE IN NATURE. 143

larger spores, on the contrary, exhibit a strong mem-
brane and dark olive-brown contents. After they are
sown the membrane swells up, and the contents become
divided, at least in some genera of the Fucoidez, into
two, four, or eight parts, which pass at once into germi-
nation, a process which reminds us of the above-described
behaviour of the spores of the Closteria and certain
Zygnemacee. As a last example of the occurrence of
double fructification in the group of Alge, I mention
Chantransia. The ordinary, long-known fructification of
this genus consists of globular, very thin coated germ-
cells, having a central rose-coloured vesicle in the light
verdigris green contents, which germ-cells are formed
separately in the terminal cells of the tufted lateral
branchlets, and are set free by the rupture of the parent-
cells. They have no independent motion, but probably
germinate directly after they are discharged; on this
point, however, we have no certain observations. In
the same plant, and indeed on the same “stocks” and
branches, there occurs more rarely a second kind of
fructification,* in which the cells forming the links of
the branches swell strongly at the side, and form a large
thick-coated spore in the protruberance, which becomes
shut off as a distinct cell.

Chantransia therefore exhibits two kinds of motionless
reproductive cells, the smaller of which are probably
immediately-germinating gonidia, the larger resting

The decision of their true import therefore requires, on the one hand, fur-
ther observations completing the history of their formation and life; and, on
the other, the discussion of the question, whether the formation of active,
and, as we have seen, in many cases sterile gonidia, is not to be regarded
as a precursor of the formation of spermatozoids, just as in a higher group,
the formation of two kinds of spores, the former of which are likewise, in
many cases, sterile, must be regarded as an anticipation of the contrast of pollen
and embryo-sac. (See Thuret, ‘Comptes Rendus,’ April 25,1853; Transl.
in ‘Annals of Nat. History,’ 2d ser., vol. xii, p. 64, who shows that the
antherozoids do fecundate the spores of Fucoidew.—A. H.

* T observed this in October of last year in a form of Ohantransia chalybea,
Fries, very frequent at Freiburg, which Kützing (‘ Sp. Alg.,’ 430) mentions
as Ch. chalybea, var. radians.

144 THE PHENOMENON OF

spores. Two kinds of thick-coated and resting spores,
macrospores and microspores, which are both found m
the same way, in fours in mother-cells, occur, lastly, in
many Lycopodiacez,* in the allied genus /socles,f and in
the genera of the Rhizocarpex, Marsilia, Pilularia, and
Salvinia. In the examples last named we have advanced
very far beyond the original simplicity of the vegetable
structure which we had before us in the first examples ;
they only admit of citation here, in so far that they like-
wise exhibit essentially similar generative series of mother-
cells, and finally go out into distinction of fructification
cells. t

In the higher groups of the Vegetable kingdom, the
difference of the fructification-cells is preceded by a still
more important difference of the vegetative generations of
cells. The distinctly qualitatively differenced reproductive
cells (fertilizing-cellsand germ-cells) formthe conclusion not
of similar, but of unlike series of generations of cells, and,
moreover, not of all, but only of certain series of generations,
while a still greater number of series attain their purpose
and destination within the vegetative organism, without
arriving at fructification in the last generation. While
in the lowest plants, all vegetative cells, as mere repe-
titions of the same thing, belong to one rank, in the
higher the cells divide, in the course of the generations,
into different ranks, by which the organism is completed
on a different side, and through which is caused a more
necessary coherence and more intimate combination than

* Göppert concludes that both the small and large spores are capable of
germination, from observation of two different forms of the young plants in
Selaginella denticulata. (‘Uebersicht der Arbeiten der Schles. Ges. fur
Vaterl. Cultur.,’ 1845, p. 129.) (Proved incorrect.—A. H.)

f According to a recent note in a letter from Dr. Mettenius (Nov. 1844),
spermatozoids are developed in the small spores during the germination of
the large spores, which confirms the analogous observation of Nägeli on
Pilularia. (‘ Zeitschr.,’ 1846, 188.)

+ (On this subject, much developed since the above was written, consult
the Report on the Higher Cryptogamia, by A. Henfrey, in the ‘Annals of
Nat. History,’ 2d ser., ix, 441, which also gives most of the new literature
of this subject.—A. H.)

REJUVENESCENCE IN NATURE. 145

we have seen in the lower stages, where each cell strives
to vegetate for itself alone. The development of different
ranks of cells, with which is connected the realisation of
the organic differences in the vegetative sphere, in the
higher plants, is chiefly attained by the above-mentioned
production of daughter-cells of different kinds in one and
the same mother-cell, therefore by differing sister-cells.
We will examine this condition in a few examples of the
simplest kind, so as to indicate the path by which nature
advances in the production of the multiplicity of cell-
formation of one and the same plant.

We meet with the first separation of vegetative per-
manent cells from series of generations terminating in
reproductive cells, in the Nostoc-like Alge. ‘The
necklace-like filaments of Nostoc, composed of a row
of cells, exhibit at one or both ends, as also here and
there in the course of the filament, particular cells
distinguished from the rest by size, regular rounding,
thick membrane, and pale, homogeneous contents ;
while the remaining, smaller, thin-coated cells, filled with
darker and often granular contents, continue to multiply
in rapid succession by division, until they finally, in the
last generation, fall apart as germ-cells, exhibiting no
perceptible difference from the preceding generations.
The large terminal and interstitial cells just named
remain almost unchanged, neither undergoing further
vegetative division, nor taking part in the propagation.”

The origin of these peculiar boundary-cells can only
take place by certain of the cells dividing mto two unlike
daughter-cells, one of which becomes a vegetative per-
manent cell, the other a mother-cell of a series of uniform
generations of cells, terminating in fructification. It is
probable that the very first cell (the germ-cell) divides in
this way into two unlike cells,f and then, when a filament

* These cells have been hitherto incorrectly regarded as seed-cells,
(spermatia, Kg.).
+ Very young plants of Nostoe (or Hormosiphon 7), exhibited a short fila-

ment enclosed by a gelatinous vesicle, having a boundary-cell only on one
side, and this lying outside the gelatinous vesicle.
10

146 THE PHENOMENON OF

has been formed, this must be repeated, but in the
reverse direction, by the cell at the opposite end, as well
as by certain others lying in the midst of the filament.
This first division into two unlike cells may be regarded
as the rudiment of an apical growth, which, however, is
arrested at the first step, since, after the production of a
single cell of the second order, the further division of the
cell of the first order of the second degree (the apical
cell), produces merely cells of the first order. Anabaina
(to which may be added Spherozyga and Spermosira*)
and Cylindrospermum are distinguished from Nostoc by
the occurrence not merely of two, but of three modifi-
cations of cells, since the cells multiplying by continued
division (the cells of the first order) do not all behave
alike in the last. generation, but partly expand into larger,
thick-coated seed-cells, doubtless destined to a long
period of rest, and partly remain small and thin-coated,
and then perhaps perform the function of a second kind
of reproductive cells, corresponding to the more gonidium-
like germ-cells of WVostoc, but, perhaps, at least in many
cases, die away as sterile cells, when the filament breaks
up. In Anabaina several of the intermediate cells of
each section are developed into the larger seed-cells ;
in Cylindrospermum the lateral cells immediately bound-
ing the terminal or interstitial cells.

The filaments of the Nostochinez exhibit, otherwise, no
perceptible contrast at the two extremities, and their in-
tertwined and irregular position admits of no distinction
into an upper and lower end. In the group of the
Scytonemex and Rivulariee (excluding the Masticho-
tricheae) a contrast of this kind is distinctly present, but
still without any root-like formation of the lower end,

* These three genera are so loosely defined by Kützing, that we cannot
form any clear idea of his distinctions. Anabaina seems to me to be only
sterile Spherozyga, and Spermosira to differ merely by shorter aud more dis-
coid cells, and Nodularia may be a sterile condition of the last form.

{ I found indications of such a contrast in Cylindrospermum humicola, Kg.,
and other species, in which one end decidedly comes to its full development
later than the other.

REJUVENESCENCE IN NATURE. 147

which is formed by a vegetative permanent-cell, like the
boundary cell of Nostoc. In Tolpothriz and Schizosiphon
several such vegetative permanent-cells frequently occur
at the base of the filament, and in these very genera, as in
Scytonema and Euactis, the formation of them is repeated
at intervals in the course of the filament, where they
appear as interstitial cells, which by ‘subsequent parting
of the filament, and the lower part overgrowing the
upper, become basilar-cells of seeming branches. In the
Scytonemez, the filaments are of pretty uniform structure
throughout the whole length, but in the Rivulariez they
run out above into a more slender capillary point or
flagellum. It is not yet made out whether the distinction
of the upper and lower end of the filament of the Algz
of this group is caused by an apical growth continued on
beyond the formation of the first basilar cells, but this
much is certain, that the cells of the filaments multiply,
in their further growth, as in the Nostochinez, by repeated
halving, which, however, does not terminate simultane-
ously in all parts of the filament, but continues longer in
some parts than in others. In the Scytonemez it is
carried on farther in the points (not merely of the entire
filaments, but also in the individual sections).* In the
Rivulariaceous genera Mastichothriv, Mastichonema, Rivu-
laria, &c., in the lower; in Zuactis, in the intermediate
parts. With this is associated a distinction of the cells
belonging to the different parts of the filament, becoming
continually more evident with the progress of the division,
and especially marked in the last generation. In the
Scytonemeze the cells pass into germ-cells, in the last
generation, mostly only at the upper part of the filament ;
in Euactis only in the intermediate ; in Mastichothriv and
Mastichonema only in the lower, and thicker, not in the
upper capillary portions ; in Rivularia, lastly, the cells of
the lower thicker part exhibit another difference, for the

* In many species of Seytonema and Tolpethrix the lower end of the
sections may grow out in this way into new points.

148 THE PHENOMENON OF

lowermost (adjoining the basilar permanent-cell) becomes
a large cylindrical, thick-coated seed-cell, as in Cylindro-
spermum, while the following shorter cells, richer in con-
tents, are perhaps to be regarded as a second kind of
germ-cell.*

From these examples of less decided and often still un-
settled contrast of growth in the rows of cells chained
together into filaments, let us direct our attention to cer-
tain others, in which the contrast of ascending and
descending growth becomes more evident, on the one side
by distinct root-formation, on the other by undoubted
terminal development of the row of cells (cell-forming
apical growth). This condition is exhibited in the sim-
plest way, namely, by a filament-stem always single, in
Ulothrie and Gdogonium, two genera, otherwise very
different, which recent Algology has extracted from the
earlier chaos of Confervee. Ulothriv zonata + has active
germ-cells, of which 8—16, or in weaker parts of the
filament sometimes only four are formed in one mother-
cell. These are of longish-ovate form, having four very
fine cilia at the anterior pale extremity, and a red vesicle
elongated in the transverse direction in the interior, lying
at the side, about the middle. After swarming for at
most two hours, these germ-cells come to rest, and
immediately germinate. The cell then becomes elongated
in two opposite directions, growing out in one, into a
slender, hyaline, simple (or bifurcated at the point) fixing-
root; at the other, extending cylindrically, and forming
the commencement of a green filament-stem. Usually on
the second day the first cell divides into two, about in
the middle of the upper green end, and thus are produced
a lower root-bearing end, dividing no farther, and an
upper end which, after growing to not quite twice its

* It sometimes appeared to me as though the seed-cell, or the so-called
manubrium of Rivularia originated by re-fusion of several previously separate
cells, analogous to what occurs in Palmoglea; but I could not attain a com-
plete conviction of the truth of this.

+ Vide Kützing, ‘ Phyc. generalis’ (1843), t. lxxx. (Also Schacht, die
Pflanzenzelle,’ 1842, p. 120.—A. H.)

REJUVENESCENCE IN NATURE. 149

original length, separates again into a posterior longer,
and an anterior shorter, cell; which latter repeats the
same process, and so on. Thus, by a continually repeated
division of the apical cell into two unlike cells, is formed
a series of cells of a second order, the link-cells of the
filament, the first of which is at the same time the root-
cell. The filaments of Ulothrix zonata, once formed, grow
no more in thickness, but gradually increase in diameter,
from the base to the summit, in such a manner that the
anterior parts often appear thrice or four times the diameter
of the posterior, lying nearer the root.* The root-cell,
as well as those next succeeding it, remain unaltered and
are infertile; the following link-cells, on the contrary,
after they have attained a length about twice their
diameter, divide into two equivalent cells, consequently
into cells of the second generation of the second order,
whereby, since no further elongation takes place, cells are
produced of about equal length and breadth. Still farther
forward, therefore in the thicker part of the filament,
this division is repeated once or twice more, so as to give
rise to cells of the third or fourth generation of the second
order, the length of which is only } or } their diameter.
Finally, in the cells of the last generation of the second
order, the germ-cells are produced by division of the
contents alternately in the three directions of space.
The filaments of @dogonium, in their earlier development,
follow the same course as those of Ulothrix zonata, but
differ in the subsequent subordinate division of the
original link-cells, since these do not divide into equiva-
lent cells, but into unlike cells, forming series of link-cells
of the second degree, which is moreover accompanied by
a longitudinal extension of the subordinate link-cells.
The lowest link-cell, which expands at the base into a
discoid, often elongately lobed root-foot, and is always of

* Hence the great variability in the diameter of the filament, which
varies from 145 to 145, or sometimes 785 millim.
+ Vide Nägeli, ‘Algensysteme,’ p. 137, t. i, £.53, 54.

150 THE PHENOMENON OF

greater diameter, and more bellied out than the suc-
ceeding, is the only one which divides no more, and
constantly remains sterile. ‘The resting spores of this
genus are formed in the swollen end-cells of the subor-
dinate rows of links.*

The Ramification, like the apical growth, of the many-
celled Algze, depends upon a division of the cell into two
unlike parts, one of which retains the character of the
mother-cell, and the other deviates; while, however, in
apical growth the differing cell belongs to a higher order
of cells, in ramification the differing cell returns, on the
contrary, to a lower order, since it becomes a cell of the
first degree of the first order, that is, the primary cell of
a new series of generations.

Ramification is exhibited in its simplest form in Siro-
siphon (Hassullia) and Haplosiphon.t Particular cells of
the rows which form the filament-stem of these Alge,
divide in the perpendicular direction into two unlike
cells, one of which, mostly larger, remains as a link-cell
of the principal filament, while the other, elongating in
the horizontal direction, emerges from the stem as a new
axis, and then divides again, at right angles to the new
axes, into two unlike cells,—a new apical cell, and a first
link-cell of the branch. The further development of the
branch takes place, as in the principal axis, by repeated
division of the apical cell, which is followed subsequently
by a division of the link-cells. The ramification proceeds
in a different way in the Cladophore (the branched Con-
Serve of the older authors), in which the branches, solitary,
or sometimes opposed in pairs, sprout forth from the
upper margin of the link-cell, where a bagging out, as it
were a new laterally projecting apex of the cell, is first
formed, which, by division of the thus enlarged cell into
the old and new parts, becomes the first cell of the branch.

* T am not acquainted with any genus of Alga with simple filaments
formed solely by cell-forming apical growth without subordinate division of
the link-cells. Among the ramified Alge, Batrachospermum forms its stem

in this way. ;
+ Kützing, ‘Spec. Alg.,’ p. 894.

REJUVENESCENCE IN NATURE, 151

The ramification in Chantransia, Bulbochete, Chetophora,
and Coleochete pulvinata, exhibits similar characters. In
the last two examples there occurs, in addition, a descend-
ing ramification from the /ower margin of the link-cells ;
so that, in many cases, an ascending branch springs
from the upper border, and a descending branch from
the lower border of the same cell. With the exception
of the reverse direction, the mode of origin of these
descending root-, or rather stolon-like branches, is the
same as that of the ascending.

A further series of very varied organic differences next
arises in the relations of the cell-formation of the branches
to the cell-formation of the stem. If the cell-formation
in the branches is limited, and the branches fall short
considerably in size of the stem, they admit of comparison
with leaves. ‘Thus, for example, in Draparnaldia, in
which the branches mostly arising in pairs from one cell of
the stem, as well as the branchlets of the second order
springing from these, are formed of much smaller cells
than the stem, the upper, larger, forming the hyaline
capillary points of the branches, while the lower and
shorter, abundantly furnished with green contents, pro-
duce within them the germ-cells. The large cells of the
stem of Draparnaldia are sterile vegetative-cells ; only
the apex of the long stem behaves in the same way as
the branches, and is, like them, fertile, and terminated by
a capillary point. In Batrachospermum, on the contrary,
the stem is unlimited in its growth, formed of a series of
link. cells, which originate through the repeated division
of a dome-shaped apical cell, and undergo no further
transverse division. From the upper border of the
young, still very short link-cells arise 5—6 radiately-
arranged projections, which are very early cut off, in the
shape of special cells, fiom the central cavity, which
remains as a link-cell, and these new cells then grow out,
by limited link-formation, into the small, again much
ramified branches, forming the peculiar globular whorls

152 THE PHENOMENON OF

which gave rise to the name of this genus. The branches
of the whorls are at the same time the bearers of the
fructification, since the spores are formed on particular
more vigorously branched and crowded parts of them,
through closing off of the terminal cells, while the sterile
branchlets, at all events in some species of the genus, run
out into capillary points formed of elongated hyaline
cells. ‘These branchlets, so strikingly different from the
main stem, remind us of the so-called leaves of the
Characex,* and this the more that their lowest cell, as
in Chara, gives rise to a peculiar cortical structure ex-
tending over the stem, with this distinction,—that in
Batrachospermum this structure is formed solely of
decending rows of cells, while in Chara it is formed of
ascending and descending rows, which unite in the middle
of the internode. From the rows of cells descending in
Batrachospermum from the base of the branchlets of the
whorls, and by growing over one another gradually clothing
the stem with a many-layered loose rind, which may be
compared with the above-mentioned root-like branches of
Chetophora and Coleochete pulvinata, arise new horizontal
branches, by which the spaces between the principal
whorls (especially in Batr. vagum and confusum) become
closely filled up with irregular accessory whorls. In
addition to the whorl-forming branches, bearing through
their limited growth the relation of leaves toward the
stem, there occur in Batrachospermum other isolated
branches unlimited in their growth, repeating the stem-

* T have already, in a former passage, in the case of Bryopsis (p. 129) and
Cuulerpa (p. 129), avoided the discussion of the question whether eaves, in
the full sense of the term, occur in these lower realms of the vegetable
kingdom. It is evident that the organic differences sharply defined in the
higher divisions of plants, are only gradually being slinimated in the stage to
which the Algz belong, and even in those cases where these differences do
preseut themselves more distinctly, they are connected with the undecided
structures by such intermediate stages, that no exact boundary can be
drawn. An absolute decision whether or not Alex have leaves, in the full
sense of the term, will not be possible until we understand more pertcetly
the course of development of the leaves of the Phanerogamia.

REJUVENESCENCE IN NATURE. 153

and whorl-formation—which branches seem to arise,
inside the whorl-branches, from the link-cells of the
stem.

Having seen, first, in the lowest stage, vegetation and
fructification united in a single cell; then, in a second
stage, a series of generations of vegetative cells, which,
however, pass in the last generation into fructification
in all the members; finally, a step farther, first only a
few cells persisting as permanent vegetative cells, side by
side with the series of generations going out into fructifi-
cation, then a gradually and continually increasing
proportion of the successive generations of cells developing
into new vegetative supporters of the fructifying parts, —
Batrachospermum at length displays to us a case of more
decided separation of an original series of generations of
cells destined to simple vegetative formation, and de-
duced or secondary series attaining fructification only in
certain terminal links. Nevertheless, comparatively speak-
ing, we are yet still among the simplest rudiments of the
differentiation and complication of the vegetable organism,
through the ever more variously divided and arranged suc-
cession of generations of cells, and the, at the same time,
ever increasing diversity of the conformation and physio-
logical activity of the individual cell. For a further advance
it becomes necessary to show how compound solid cellular
structures are formed from simple rowsof cells, the link-cells
of the stem becoming the mother-cells of new, subordinate
series of generations, which divide according to new laws
of direction in the given space of the link-cell, separating
either into similar parts, as in Myriotrichia* and
Sphacelaria, or into dissimilar, by the formation of a
circle of cells around a central cell, as Polysiphonia.t
It must be shown, moreover, how a distinction between
cortical and medullary tissue arises, through a further
continued division of the cells at the periphery of the

* Nägeli, ‘Algensysteme,’ p. 147, t. ill, figs. 13—19.
7 Kützing, “Phye. generalis,’ t, 1, f. 3. Nägeli, “über Polysipl ıonia.’
(‘ Zeitschr.,’ 1846, p. 207, t. vi and vii.)

154 THE PHENOMENON OF

stem, starting from uniform* or dissimilarf division in
the link-cells; how, moreover, the vessels are formed in
the parenchyma of the stem in the vascular plants, 7. e.,
how their origin is connected with the generative suc-
cession of the rest of the cells.{ It must likewise be
demonstrated how the cell-formation in the leaf, pro-
gressing according to fixed laws, produces the simple
cellular plate, such as is exhibited by most Mosses, and
the many-layered plate, with varied arrangement and
direction of the cells in the different layers, of the higher
plants; how here again the formation of the vascular
bundles enters into the tissue in the most diverse dis-
tribution, and how these vascular bundles are connected
in their origin with those of the stem. Finally, it must
be demonstrated how, beyond all the generations of
cells arriving at vegetative permanence and at their final
term in the graduated construction of the organism and
the contrast of its organs, certain series of generations,
withdrawing themselves from the vegetative termination,
finally attain their destination prepared, protected, and
supported by all the other series, in the formation of
reproductive cells.

We have here stated a problein, the solution of which

* Vide Styptocaulon, in Kützing’s ‘ Phycol. generalis,’ t. xviii; in Lemania
also, the formation of the compound tissue starts from a simple row of link-
cells originating by horizontal division of an apical cell, which link-cells
divide first by a cross-wise perpendicular segmentation into four, then by
recurring horizontal division into eight equal cells. In what way the
separation in the peripherical and central cells next takes place, and how the
division proceeds in the interior, it is not easy to determine; but the result
shows that. the division occurring in the interior is far outstripped by that
in the peripherical cells, since a rind is formed outside composed of two
layers of very small cells, while the interior is occupied by many-times larger
cells, separating from one another in the centre, and forming a medullary
cavity.

f Vide Piilotu (Kiitz. ‘ Phye. general.’ t. 46, vi); Naccaria (ibid., t. 44,
iv); désidiam Helminthochorton (ibid., t. 45, xi); Zaureneia (Nageli,
‘ Algensyst.,’ t. 8).

+ Unger’s treatise on the ‘Genesis of Spiral Vessels’ (Linnea, 1841,
335, t. 5) shows that the so-called vessels of plants are only rows of cells of
peculiar kind. (Transl. in “Ann. des Se. nat,’ 2d ser, t. xvii, p. 226. See
also Mohl, *Verm. Schriften,” 251; Schacht, * Pflanzenzelle,’ 185.—\. H.)

REJUVENESCENCE IN NATURE. 155

still hes far away from us; yet these observations may
serve to make clear the importance of the cell as the
organ of the graduated self-determination and isolation of
life in all its formative movements, as the constantly
renewed point of separation in growth advancing by suc-
cessive links, and to indicate how the subordinate sphere
of life of the cell is the more intimately interwoven in
the totality of the organism, the more the specific vital
purpose separates into its factors.

Examining the individual cell more closely, we must,
in the first place, observe that the term cell does not
correspond exactly to that to which we especially apply
it, for we understand as cells not merely the membranous
vesicles or utricles which form the tissue, but also their
contents; we apply the name cell not alone to the little
chamber formed by the completely closed-in wall, within
which the vegetable life conceals itself, but also to its
living inhabitant, the more or less fluid and inwardly
mobile body, which is bounded, within the chamber, by
its own more delicate coat (the primordial utricle). The
cell is thus a little organism, which forms its covering
outside, as the muscle, the snail, or the crab does its
shell. The contents enclosed by these envelopes form
the essential and original part of cell, in fact must be
regarded as a cell, before the covering is acquired. From
the contents issues all the physiological activity of the
cell, while the membrane is a product deposited outside,
a secreted structure, which only passively shares the life,
forming the medium of intercourse between the interior
and the external world, at once separating and combining
the neighbouring cells, affording protection and solidity
to the individual cell in connection with the entire tissue.
Hence the development of the cell-coat, as a product of
cellular activity, always stands in inverse proportion to
the physiological activity of the cell. In youth, thin,
soft, and extensible, the cell-coat allows abundant
nutrition and advancing growth; subsequently thickened
and therewith hardened by the deposit of lamelle, it

156 THE PHENOMENON OF

compresses the contents within continually narrower
boundaries, more and more excludes intercourse with the
external world, and puts a term to growth. Thus the
life of the plant builds its tomb in the very cell—dies
away at last in its own work.

That the origin of the cell precedes its enclosure by
acell-membrane, is shown most distinctly in those cases
in which the cell originates free, that is, without contact
with the mother-cell, or where it becomes free by being
expelled immediately after its production. The last
condition occurs in the swarm-cells, or active gonidia of
the Algs, which so long as the motion lasts, possess no
cell-membrane separable from the contents, and must
be regarded as bounded merely by the primordial utricle,
which is intimately connected with the contents. It is
well known that by the action of dilute acids or spirits of
wine, the contents of the cell are contracted and wholly
or partially removed from the cell-membrane, which thus
appears as a structure clearly separated from the contents.
The active gonidia of (Zdogonium, Bulbochete, Ulothriz,
Draparnaldia, Stigeoclonium, Chetophora, Hydrodictyon,
and other genera which I have repeatedly examined in
reference to this point, contract, when so treated, entirely,
without leaving a colourless membrane at the boundary
of the original dimensions, which does always occur after
germination has commenced. Thus the gonidia of
Ulothrie and Hydrodictyon exhibited a hyaline vesicle,
the contents of which were contracted on the application
of tincture of iodine, a few hours after they had come
to rest, on the same day that they were born. That
these gonidia possess another membrane, intimately con-
nected with the contents (the primordial utricle), is
testified by their smooth and exact outline, and further
by the phenomena which present themselves in the
solution frequently taking place soon after birth in weak
gonidia. In such cases the cell is seen to acquire a
globular form and swell up ; through absorption of water,
large hyaline cavities originate, displacing the contents,

REJUVENESCENCE IN NATURE. 157

except at a few points. The soon succeeding collapse
and dissolution of the cell is distinctly opposed for some
time by a membranous bounding-structure. In very large
gonidia, especially those of Vaucheria clavata, this mem-
brane exhibits considerable thickness, so as to be clearly
distinguishable as such, but in this very case it shows that
it possesses totally different properties from those of the
cell-membrane subsequently enveloping it: while the
cell-membrane, be it ever so delicate, appears tough
and extensible, the primordial utricle is found soft and
brittle, so that the slightest injury destroys its continuity,
which, however, takes place so as to seem rather a
separation or flowing apart of the substance than a
tearing through.* It is this primordial utricle which
bears the numerous vibratile cilia clothing the whole
surface of the cell in Vaucheria, these appearing to be
formed out of the substance of the coat itself and mere
processes of it. Iodine causes these cilia to contract to
a certain extent, and acquire a brownish-yellow colour,
which colour presents itself the more distinctly, the more
abundantly and closely the cilia are collected together,
as, after Vaucheria, is the case especially in Gidogonium
and Bulbochete, where they form a dense crown of
cilia. ‘The body of the germ-cell acquires a deep brown
colour with tincture of iodine; the hyaline apex mostly
existing in the stage of motion, as well as the primordial
utricle, indistinguishable from the contents in small
swarming-cells, have this colour, sometimes appearing a
little lighter. This colouring agrees with the well-known
behaviour of the primordial utricle of the cells of the
Phanerogamia.t ‘The cilia disappear with the com-
mencement of the rest, and before the formation of the
proper cell-membrane, not only in Vaucheria, but in all
Algze where the germ-cells have a ciliary motion of short

* So says Unger, ‘die Pflanze im Momente der Thierwerdung,’ 1845,

p- 36.
t+ Vide H. von Mohl, ‘ Botanische Zeitung,’ 1844, p. 276. (Transl. in
‘ Scientific Memoirs,’ vol. iv, p. 93.—A. H.)

158 THE PHENOMENON OF

duration. ‘The primordial utricle seems to retract its
processes into itself, before it secretes the cellulose upon
its surface. Different, and especially instructive in
reference to the relation of the cilia to the internal body
of the cell, is the behaviour in a series of Algoid plants,
in which the ciliary motion is of lengthened duration,
and which on this account have been hitherto included
among the Infusorial animalcules, namely, the Chlami-
domonada and the Volvocinee.* In Chlamidococeus
pluvialis, already mentioned above (p. 138), the active
cells, bearing cilia at the acute extremity, are born naked,
like the swarming cells of other Algz; but within a few
hours the periphery of the body exhibits a delicate,
hyaline coat, which, by subsequent fluid secretion during
the about three-days-long duration of life and growth of
these “swarmers,” becuines removed farther and farther
from the body of the cell, forming a separate membrane, as
it were, a loose coat around it. The ciliary motion persists
throughout this formation, only it gradually becomes
weaker and less active, since the cell-membrane becoming
gradually pushed up further from the base of the two
long cilia, more and more hampers their vibratile motion.
We have here, therefore, indubitable evidence that the
cilia belong to the proper body of the cell and the
primordial utricle bounding it, and not to the surrounding
cell-membrane.t Another Alga belonging to the same
group, which I have called Gleococcus, produces, instead
of the more solid cell-membrane, a semifluid gelatinous
envelope, around its green body, which bears two very
long cilia at its acute extremity, and these become en-

* Von Siebold (‘de finibus inter regnum animale et vegetabile,’ 1844,
p. 12) was the first who distinctly claimed the Volvocines for the vegetable
kingdom. (See Williamson, ‘Proc. Manchester Phil. Soc.,’ vol. ix; “Trans.
Mic. Soc. of London,’ 1853; also Busk, ‘ Microscop, Trans.,’ 1853, p. 31.
—A. H.)

+ Vide Von Flotow, ‘Act. Acad. Nat.Cur.,’ xx, p. 2, 1844, t. 25, f. 58—70;
in reference to which figures, however, I must observe, that I have never
found the cilia retracted completely within the membrane. (Compare Cohn,
‘Nova. Act.,’ xxii, and Abstract in this vol. ; also Schacht, ‘ Die Pflanzenzelle,’
p. 124.—A. H.)

REJUVENESUENCE IN NATURE. 159

tirely absorbed into the gelatinous envelope.* In Gonium,
Volvox, Pandorina, and a plant similarly formed of eight
closely connected cells, which perhaps is Kiitzing’s
Botryocystis Morum, each cell likewise possesses two
cilia, which, issuing from the internal body of the cell,
project through the gelatinous envelope, and set the
whole family in motion by their vibrations.

The absence of a proper cell-membrane in the new-
born gonidia of the Algee is placed still further beyond
doubt, when their origin and birth is closely observed.
We will examine both somewhat more closely in Ulothrix
and Cidogonium. In Ulothrix, as above mentioned
(p. 149), the cells of the filament undergo many divisions,
but always in the same direction, at right angles to the
longitudinal axis of the filament (horizontal division).
As soon as the division is completed, the contents may
be separated from the newly-formed wall by acids or
tincture of iodine, which proves that such a separation is

* The genus Gleococcus exhibits the following characters: ovate, green
cells, with a colourless point, from which a reversed funnel-shaped, lighter
space extends inwards, together with a largish vesicle at the posterior
extremity. Multiplication by simple or double, in the last case decussating
halving, after which the cells remain loosely connected together by secretion
of soft. gelatinous confluent coats, forming globular, and, finally, amorphous
families. The cells of all the generations succeeding each other during the
formation of these families (excepting the transitory cells in the case of
double halving), are provided with two very long persistent. cilia, which only
disappear when division commences. The cells exhibit a feeble motion inside
the enveloping and connecting jelly, the anterior end jerking in and out, or
suddenly retracting a little. The last generation of the family leave the
gelatinous mass and swarm out, to settle down quickly in some other place.
It is probable that the formation of a new family is preceded by a longish
stage of rest,—perhaps there are several resting generations,—but we have
no observation on this point. In Gl. mucosus the full-grown cells are „sth to
shth of a millimeter long, the “ phytodoms,” or family stocks forming at the
bottom of little ponds, attain the size of an apple, and are of compressed
globular, often lobed shape, till they at length break up, and come to the
surface of the water in irregular fragments. The gelatinous mass has a
peculiar greenish spotted aspect, which depends upon subordinate groups of
generations being more closely packed together. Another form, perbaps
specifically distinct (G2. minor), appears in the springs at Freiburg, in the
spring, in the form of light yellowish-green, often pear-shaped “ stocks,” at
most as large as a hazel-nut, attached to the sides of the gutters of the
springs, finally becoming detached, swimming, and shapeless. The cells are
somewhat smaller, 15th to 7sth of a millim. long.

160 THE PHENOMENON OF

possible, when a cell-membrane is very young and delicate.
With the commencement of fructification a new law of
division displays itself, namely, a successive division of
the contents in the three directions of space, beginning
with two perpendicular divisions crossing at right angles,
which are followed by the horizontal division, and some-
times by another perpendicular division. These divisions
succeed one another so rapidly, that it is seldom possible
to see the first divisions without the last. Even this
circumstance renders it improbable that a formation of
cell-membrane takes place at once after every division,
enclosing the segments ; and the phenomena occurring at
the birth of the germ-cells, which I shall subsequently
describe, show completely the inadmissibility of such a
supposition. By progressive division, first two, then four,
then eight, and finally sixteen cells originate, in the way
described, in the individual link-cell. If each division
were immediately followed by a secretion of cell-mem-
brane, the originally simple chamber of the mother-cell
must become divided, successively, into two, four, eight,
and sixteen chambers, the soft plates of cell-membrane of
the newly-formed walls, since they would immediately
touch, must grow together, and the last parts (the germ-
cells) produced by the process of division would thus be
placed in a framework formed of a four-fold enclosure,
and solidified by the cohesion of the vesicles packed one
inside another. Not the slightest trace of such an
apparatus of chambers can be seen at the birth of the
germ-cells. If, then, the separate divisions of the contents
are, nevertheless, followed by formation of cell-membrane,
the entire series of special parent-cells must, in the few
hours in which division and birth takes place, not only
be formed, but also immediately re-absorbed, an assump-
tion which here, as in other cases of transitory cell-
formation,* would appear altogether arbitrary, and

* The absence of formation of cell-membrane from many generations of

cells may be ascertained with especial clearness in many Palmellacex, in
which, instead of a thin, firm, cell-membrane, a thick, soft, gelatinous

REJUVENESCENCE IN NATURE. 161

unsupported by any observations, ‘The birth of the
germ-cells of Ulothrix zonata takes place in the following
way:—T'he mother-cell opens laterally by the tearing of
the cell-membrane ; the innermost delicate layer of the
membrane of the mother-cell does not share in this rent,
but, swelling and expanding by absorbing water, and
loosened by this expansion from the outer membranes of
the mother-cell, it protrudes in the form of a sac. Only
rarely does this sac tear during its protrusion, and let out
the germ-cells singly: in most cases it by degrees
emerges entire, and, as a globular vesicle, still holds
the germ-cells, already actively moving, imprisoned for
some time in its interior. Finally the sac bursts, and
the germ-cells separate rapidly in all directions. Even
after the emptying it may be still detected as a delicate
water-clear vesicle, withont the slightest trace of
secondary mother-cell membranes in the interior. Some-
times miscarriages occur, demonstrating the absence of
the latter still more absolutely. It happens, namely,
sometimes, that the germ-cells do not become detached
from the mother-cell vesicle, but remain coherent with it.
Such vesicles are born like the others; the included germ-
cells become separated from one another by the expansion
of the vesicle, without being able to leave its walls. In
these cases, again, no trace of interposed membranes can
be seen. I have observed a very similar process, without,
however, a tearing of the vesicle, in which indeed the
active germ-cells combine into a regularly-arranged
colony, in Pediastrum.*

In Gdogonium+ only a single germ-cell is formed in
envelope is formed, often alternating with more delicate membranous
lamelle, in which, therefore, the omission of the formation of these envelopes
is very striking. See, as an example, the figure of Gleocystis vesiculosa in
Nageli’s ‘ Hinzelliger Algen,’ t.iv,r. The multiplication takes place through
simple or double halving, i. e. vegetative development and formation com-
mences sometimes directly after the first division into two, sometimes after
the second; the two transitory cells first formed producing no membrane.
oy case is represented in fg. n, the last in figs. o and / of the plate

* Vide plates iii and iv, and the detailed description in the Appendix.
7 (See Thuret, ‘Ann. des Se. nat.,’ 3 ser., xiv, 17, pl. xix.—A. H.)
1l

162 THE PHENOMENON OF

each cell of the filament. The birth of these is effected
by an extremely regular bursting of the parent-cell in the
direction of a transverse annular fold, occurring near the
anterior end of the cell, so that the cell opens as it were
by a lid, the detached upper portion often remaining
fixed at one side, and opening only laterally, the result of
which is of course a knee-like bending, when the opening
cell lies in the middle of the filament. The cell-contents
previously lying closely applied upon the cell-wall, and
merely betraying the impending birth by their darker
colour, are then very gradually extruded through the
opening of the box-like cell, exhibiting, even during
the movement, at the posterior end lifted up from the
bottom of the cell, a brighter spot, which after the birth
becomes more distinctly developed as the nipple-shaped,
hyaline apex, bearing the wreath of cilia. During the
birth the germ-cell is here also preceded by an extremely
delicate vesicle, which gradually expands into a large sac,
the posterior end of which, however, never leaves the
mother-cell. This sac is often not torn through for
several minutes, but then it sets free the swarm-cell,
already revolving while inside, which darts away from it
like an arrow. The vesicle is here neither more nor less
than the innermost layer of the mother-cell, still soft,
taking no share in the dehiscence of the mother-cell, and
expanding by the absorption of water. It is coloured
distinctly blue by the application of tincture of iodine,
even without previous treatment with sulphuric acid.
That the germ-cell set free from its prison in the
manner described, does not yet possess a cell-membrane,
but represents merely the mass of contents of the mother-
cell, is testified, as in Vaucheria, by its want of cohesion.
I once saw, in Gidogonium apophysatum a small torn-off
piece of the cell-contents left behind and assume the
shape of a separate globule, which did not arrive at
birth and movement, but remained in the cell. Probably
the original cause of the tearing in this case was a slight
adhesion of the cell-contents to the cell-walls, at a small

REJUVENESCENCE IN NATURE. 163

point in the hinder part of the cell. In Vaucheria clavata
I have often seen a separation of the germ-cell into two
about equal portions, through a constriction* occurring
during the birth between the anterior, already born, and
the posterior portion still jammed in the elastically con-
tracting mother-cell (the c/ud). I observed a similar case
in Stigeoclonium subspinosum. A germ-cell half born,
@. e., protruded through the lateral opening of the mother-
cell, became constrieted by the contraction of the small
orifice of the elastic mother-cell, in such a way that the
posterior portion could no longer penetrate. The part
which had emerged, bearing the cilia, acquired a
tremulous motion, which became the stronger the more
the constriction cut it off from the posterior imprisoned
portion, till at length it hung only by a fine thread.
Finally, the born portion broke Joose and hurried away,
while the unborn piece remained behind in the mother-
cell. The entire process lasted some minutes.t

That the formation of the cell-membrane does not take
place until after the cell is separately constituted, is fur-
ther shown by all those cases in which the formation of
new cells takes place freely and without contact with the
membrane of the mother-cell. In the formation of the
resting seed-cells of Gdogonium we see the thickish cell-
contents, composed of greenish coloured mucilage, mixed

* See the vivid description which Unger gives of this process (I. c.,
pp. 23-27). But where the author of this interesting treatise asserts that
the escape of the germ-cell of Yaucheria is passive, and not a really inde-
pendent act, I cannot agree with him. The swelling up of the club before
it tears, together with the hemispherical vaulting of the lower cross-wall
pressed downward in the filament, show clearly that the contents of the
club undergoing conversion into the germ-cell, acquire a development which
the firm membrane of the parent-cell cannot follow, so that this is brought
into a condition of violent stretching, which results at length in a rupture,
and, in consequence of the contraction of the walls, the gradual squeezing
out of the germ-cell.

t+ (I have observed in a species of Chlamidomonas, while four active
gonidia were being set free by the solution of the cellular membrane con-
necting them as produced from a resting vegetative cell, one of them divided
into two, so that five were produced. I saw the entire process, which
occupied about an hour.—A. H.)

164 {HE PHENOMENON OF

with chlorophyll and starch vesicles, which, in the
earlier vegetative period of the cell, form a lining of
the wall, retreat from this membrane, and present
themselves as a new, everywhere free cell destined for
reproduction. The cell-body thus detached from the
walls, appearing in a new form, with a new vital direc-
tion, presents itself with regular form and boundaries,
before a trace of the cell-membrane subsequently clothing
it is visible. It mostly assumes a perfectly globular
form, even when the mother-cell is longish ;* in this first
period of formation its surface appears somewhat uneven
from the projection of chlorophyll-vesicles ; the whole
internal cavity is filled up, and of deep green colour.
Very slowly and gradually there appears, first a simple,
afterward a double, and sometimes even a triple-layered
membrane upon the surface, while the chlorophyll and
starch formations in the contents progressively vanish, and
give place to reddish oil-drops, which at length occupy
nearly the whole cavity, and give the seed-cell a brownish-
red, sometimes even a red-lead coloured appearance. The
seed-cells of the Zygnemacee originate in the same way
as those of Gdogonium, with the single distinction that
in the former the contents of two chambers become united
to form one seed-cell.F The formation of the cell-mem-
brane, succeeding the shaping out and limitation of the
cell, as a secondary phenomenon, may be well observed
also in Spheroplea.} ‘The links of this Conferva are of
unusual length, 10—20 times as long as broad. The
distribution of the contents is extremely elegant, and
allows, in some measure, of a comparison with that in
Spirogyra, with this difference, however, that the chloro-
phyll forms, not spiral, but annular bands, 20 or 30

* Thus especially in @dogonium Landsboroughii, Hassall.

t Vide Nägeli, ‘Ueber freie Zecll-bildung’ ‘ Zeitschrift,’ 1847, p. 97.
(Transl. in Ray Society’s publications, 1549, p. 98.)

£ My observations on this remarkable genus of Ale were made in the
autumn of 1847, on Spheroplea Lruunii, Kz., (Sp. Alg.,’ 462.) (Vide also
Fresenius, ‘ Spher. annulina,; ° Bot. Zeitung.” 1851, vol. ix, 241.
—ıi.H)

REJUVENESCENCE IN NATURE. 165

of which girdle the internal cavity as green zones, in each
cell. In the median line of these zones are found, as in
the spiral bands of Spirogyra, starch-vesicles, from five
to seven in each ring; the surface of the rings, moreover,
appears spotted with very fine granules, and the margins
irregularly denticulated. The outer surface of the zones
lies flat upon the cell-wall, the inner surface projects with
a strong “keel” into the cavity. The whole series of
zones are connected together by a delicate, colourless,
mucilaginous layer or primordial membrane, which linés
the whole of the internal surface of the cell-membrane,
and which is traversed by extremely delicate lines and
branched and anastomosing green longitudinal streaks
issuing from the teeth of the zones. But the strangest
peculiarity of the conformation of the cell-contents of
Spheroplea lies in the chambering which occurs in them.
Each zone supports a delicate, colourless diaphragm,
arising from the annular keel or ridge, and stretched
across the cavity of the cell. These septa, which convert
the cavity of the cell into a many-chambered tube, have
no association at all with the external cell-membrane,
they are merely connected with the mucilaginous layer,
and formed of the same substance as this. I have had
no opportunity of tracing the origin of these chambers,
as I have never been able to find Spheroplea m a suffi-
ciently young state; but it can scarcely be doubted that
their presence and arrangement is to be explained by the
production of a row of water-bubbles in the originally
homogeneous contents (protoplasm) of the cell, which
idea is borne out by the not unfrequent occurrence of
larger and smaller intermediate vesicles lying in the zones
themselves. ‘The whole of this artfully arranged struc-
ture of cell-contents collapses as soon as the fructification
commences. First the zones become somewhat detached
from the cell-membrane, so that the internal tube appears
constricted by bands and articulated ; then the primordial
utricle, with the septa, vanishes altogether, the green zones

166 THE PHENOMENON OF

become broken up irregularly; we see them fall in, tear
up, and separate into little amorphous masses. From this
solution the contents soon gather up into a new structure;
the irregular green pieces become rounded, and take the
shape of regular, accurately defined globules, of which
two or three times as many are produced in each parent-
cell, as there were previously chlorophyll zones present ın
it. In the first period after their origin, these balls,
developing into seed-cells, exhibit a weak vibratory or
revolving motion, but they soon come to rest, and become
enclosed in a smooth, colourless cell-membrane, which,
however, is shortly afterwards peeled off again, and
replaced by a second, rough and papillose cell-membrane
of considerable thickness.* The originally green colour
of the contents is gradually changed into a brownish,
brownish-violet or, in other species, bright red-lead colour.

Nägeli has observed in Bryopsis Balbisiana and other
Algee,t an abnormal formation of free cells out of the
broken-up cell-contents of old cells, not unlike the normal
formation of the seed-cells of Spheroplea ; these observa-
tions also confirm the secondary formation of the cell-
membrane on the surface of portions of contents already
individualised, 2. e. shaped out into cells. With the last-
named phenomena may be associated the processes of
reorganisation, also observed by Nageli, in injured and
partially decaying cells, which show that the surface of
contents retracted from the cell-membrane by partial
disturbance, clothes itself anew with membrane by con-
tinuous secretion of cellulose, and indeed that the healthy
portion of the cell-contents has the power of cutting itself

* Kützing ascribes to the spores of a Spheroplea an outer coat formed
of a filiform structure wound spirally round the inner membrane, which
doubtless depends on a misconception.

r Vide Nageli, ‘ Ueber freie Zellbildung,’ 1. c., 24-26, t. iti, f. 1-3. (Transl.
in Ray Society’s publications, 1849, pp. 96-98, t. ii, f. 1-3.)

f Vide ieee ‘ Wandstand. Zellbildung,’ &e. ° Zeitschr.,’ 1844,
p- 91-95, t. 1, fig. 8, 11, 12. (Transl. in Ray Society’s publications, 1845,
pp. 268-71, pl. vii, figs. 8, 11, 12.)

REJUVENESCENCE IN NATURE. 167

off from the decay commencing in another part, by a
sharp line of demarcation, and of coating this boundary
with cell-membrane.

The constitution and defined material isolation of the
cell before the formation of the cell-membrane, has been
observed in the free formation of the germ-cells of the
Phanerogamia, as well as in the germ- and seed-cells of
many Alga. According to Wilhelm Hofmeister’s re-
searches on the Origin of the embryo of Phanerogamia,*
researches widely extended and carried out with admirable
acuteness,—after the formation of a few nuclei the proto-
plasm accumulated in the end of the mother-cell of the
germ-cells (the embryo-sac) next the micropyle, divides
into two or three longish, rounded balls, each of which
encloses one of the nuclei. These balls display no trace
of a cell-membrane in their earliest condition, and when
they lie long in water, fall away into an amorphous semi-
fluid mass; but they very soon become coated with a
cellular membrane, and then are no longer liable to
destruction, even from a long-continued action of water.
These cells formed free in the contents of the embryo-sac,
are the first rudiments of new plants, the germinal
vesicles, as they are termed, only one of which is usually
developed, through fertilisation taking place subsequently
to their formation.

That which does not admit of doubt, in the cases just
considered, where it is possible to observe the pro-
cesses on the free surface of newly formed cells, namely,
the secondary production of the cell-membrane around
the already existing and defined body of contents of the
cell, must certainly hold good also of those cases where
the division of a mother-cell into two daughter-cells is
apparently effected through the formation of a mem-
branous septum. If it be once certain that the cell-
membrane is formed by secretion on the surface of the

* Vide Hofmeister, ‘Der Enstehung des Embryos der Phanerogamen,’
(1849), p. 4 et seq.

168 HE PHENOMENON OF

cell, in this case also the formation of the separating
membrane must be secondary, that is to say, the division
and opposite limitation of the contents of the two new
cells must take place before the septum can be formed
between them by a secretion derived from the two sides
and uniting at the surface of contact. Whether in this
kind of cell-formation, which is most simply distinguished
by the term cell-formation by division,* the separation of
the two cells takes place simultaneously over the whole
surface of contact, as Nageli seeks to demonstrate, or
advances gradually, as it were by an annular constriction,
from the periphery to the centre, as Mohl represents in
some examples, and Unger assumes as the universal law
of vegetative cell-formation, is one of the most difficult
problems in the study of cells. In a subsequent passage
i shall endeavour to establish the existence of both con-
ditions. If, in the latter case, namely the division of
the contents by a gradually advancing incision and
shutting off, the secretion of cellulose kept pace with the
division, it would naturally result that the division would
seem to be effected by an annular process of the cell-
membrane growing inward from the wall.

If we have recognised that the secondary formation of
the cell-membrane is the general rule, there can only
exist one more difference of opinion, namely, as to when
the secretion of the cellulose or allied substance on the
surface of the contained mass commences. In most cases
the commencement of this secretion would certainly coin-
cide with the conclusion of the external limitation of the
cell-mass, as the moment in which the creation of the
cell, as an individualised sphere of formation, appears
completed, and the outward development of the cell
begins ; and the very young cell may therefore frequently
possess a delicate cell-membrane in such cases, where it

* Unger, ‘Ueb. merismatische Zellbildung bei der Entwicklung des
Pollens,’ denominates this process merismatie cell-formation; (Nägeli,
‘Zeitschr.,’ 1844, p. 73,) calls it parietal cell-formation around the whole
contents. (Ray Society Traus., 1845, p. 252.)

REJUVENESCENCE IN NATURE. 169

appears to be still devoid of a coat. Only transitory cell-
formations, as I have endeavoured to show in certain
examples above, remain without a coat of cell-membrane,
and in the active gonidia of the Algze (with the exception
of the permanently moving cells of the Volvocinez), the
commencement of the formation of the cell-membrane, in
all probability, does not commence until after the stage
of ciliary motion, the endurance of which is, however,
mostly very short, never extending beyond a few hours.
We have already ascribed, in the foregoing, the
accurate limitation of the cells not yet clothed with a
cell-membrane, to a coat belonging to the very body of
the cell, not to be confounded with the cellulose envelopes;
and we have sought especially to characterise as an
example of this, the ciliated coat of the gonidium of
Vaucheria, which may fully claim the title proposed by
Mohl—“ primordial utricle.” Whether, however, the
occurrence of such a coat, distinguishable from the
remaining mucilaginous contents or protoplasm of the
cell, as we see it in Vaucheria, is an universal pheno-
menon, or whether the primordial utriele described by
Mohl* is not rather a mere coat of protoplasm, a layer of
mucilage lining the inside of the cell-wall,f produced
through the protoplasm, originally wholly filling the cell,
becoming excavated by a cavity filled with watery fluid,
is a question which requires for its settlement more exact
and extensive researches than we at present possess.
Isolated, easily observed cases do indeed indicate that
the mucilaginous layer of full-grown cells is not a simple
protoplasmic investment, but is composed of two or three
differently organised layers, the outermost of which, re-
presenting the proper coat of the cell-contents, is very
probably formed in the earliest period, as the original

* Vide H. von Mohl, ‘Bemerk üb. den Bau des veg. Zelle.,’ Bot. Zeit.,
1844, p. 275. (‘Trans. Taylor’s Scient. Memoirs,’ vol. iv, pp. 91-92); and
‘Ueb. die Saftbew im Innern der Zellen,’ ‘ Bot. Zeit.,’ 1846, p. 74. (‘Transl.
Annals of Nat. Hist.,’ vol. xviii, p. 1, 1845.)

+ This is Nägeli’s view, (‘Zeitschr.,’ 1844, p. 91,— 1847, p. 38).
‘Transl. in Ray Society’s publications, 1845, p. 268,—1849, p. 110.

170 THE PHENOMENON OF

boundary structure of the cell-mass (the portion of con-
tents becoming individualised into a cell), and in this
case, just like the coat of the gonidium of Vaucheria,
claim may be made to the title of primordial utricle.
Thus, in the Characex we find a mucilaginous layer,
thicker or thinner in proportion to the age of the cell, in
circulating motion ; but outside the circulating mucilage
exists a motionless soft coat, to which are attached the
regularly arranged chlorophyll vesicles. In the earliest
stage of formation of the cell, before the commencement
of the circulating motion, the mucilaginous contents,
surrounding a nucleus, fill up the whole cavity of the
cell. The flowing movement, which carries along with it
the nucleus still visible for some time, first commences
after a hollow space filled with water has been formed in
the cell; but the separate formation of the primordial
membrane taking no share in this motion, must have
been completed before the commencement of the circu-
lation. In Gdogonium, in the contraction of the contents
connected with the death of the cell, we frequently see
the mucilaginous layer divide into a double utricle, an
outer, lighter coloured, and an inner, darker coloured,
and never contracted. The compound nature of the
mucilaginous layer of (Zdogonium may be detected even
in the living cell, by the different arrangement of the
chlorophyll in the two layers. In the outer layer the
chlorophyll forms delicate longitudinal streaks, anasto-
mosing here and there, and thus forming a network with
narrow meshes; the chlorophyll vesicles, which are ulti-
mately arranged in rows, are formed in these originally
anorphous streaks. Inside this light-green, long-streaked
net, we see, especially clearly in (2. fonticola and @.
capillare, a coarser, darker green net, forming a few
irregular meshes, extending more in a cross direction, in
which net are imbedded large starch vesicles (in the
former species one or two, in the latter a greater number).
In this inner layer is found also the parietal nucleus,
remaining visible for a very long time. Finally, in

REJUVENESCENCE IN NATURE. 171

Hydrodictyon, I have most clearly observed a composition
of the mucilaginous layer of three distinct lamellae. When
the cells of the full-grown Water-net are treated with
dilute hydrochloric acid, the entire contents are ordinarily
contracted from the cell-membrane as a closed utricle or
tube, smooth on the surface, and no laminar separation
can be detected in it. Sometimes, however, and as it
appeared to me, in diseased cells, previously near their
dissolution, there occurred, as in (Zdogonium, a separation
into an outer paler, and an inner, dark-green utricle, the
former exhibiting a smooth, the latter a rough surface,
and remaining connected here and there with the outer
utricle by thick mucilaginous threads or ¢rabecule, which
originated through the inner, more strongly contracting
utricle, drawing out the mucilaginous substance of the
outer in the form of filaments, at these points, where it
does not become completely detached from it. ‘This
phenomenon would not speak in favour of a membranous
structure and consistence of the outer utricle ; but further
investigation shows that this outer utricle is not simple,
but formed of two distinctly different layers, an extremely
delicate pellicle, accurately defined inside and out, and a
less sharply defined, somewhat thicker layer of mucilage,
—which two layers separate from one another at various
places, so that they may be very clearly distinguished.
The entire contents of the cell of Hydrodictyon exhibit,
proceeding from without inwards, the following sections:

1. The primordial membrane. It is of scarcely mea-
surable thickness, colourless, opakish, and very finely
and uniformly punctated, which depends on its being
composed of closely conjoined, extremely minute globules,
which, according to my estimate, can be at most between
woth and sicth of a millim. in diameter. ‘This extremely
delicate structure has a totally different character from
the inmost layers of the cell-membrane, for it is dimin-
ished in diameter, and retracted from the cell-membrane
by the action of acids, while the inmost layers of the
cellulose remain connected with entire cell-membrane,

172 THE PHENOMENON OF

and indeed swell up more strongly than the outer layers,
thus often falling into wave-like folds. ‘The layers of the
cell-membrane do not exhibit the slightest trace of punc-
tation, or of a composition from globules; they are
always homogencous and hyaline.

2. The outer mucilaginous layer. This is thicker than
the primordial membrane, but far thinner than the inner
mucilaginous layer. When separated from the primordial
membrane, its outer surface appears rough and wavy, as
also its inner surface, which is connected ‚here and there
with the inner mucilaginous layer by stretched mucila-
ginous threads, and hence often appears torn on the
inside. It is also opakish, of a yellowish colour, and
exhibits largish, irregular, and indistinctly defined muci-
lage-granules.

3. The inner mucilaginous layer. This is the thickest
of the three layers, rough on the outside, wavy, and
exhibiting large, strong projections on the inside, de-
pending on the starch-vesicles occurring in it. Only this
layer is green, and, indeed, in vigorous and healthy cells,
of a continuous green colour, strewn over besides with
innumerable, mostly rather largish, dark-green granules,
about „th of a millimet. long, which sometimes form
interrupted, curved, and much intertwined rows, but more
frequently appear uniformly scattered. These granules
are not yet distinguishable in young cells. This layer
also contains the starch vesicles, which appear as bright
globules, of at most j;th of a millim. thickness. Their
number increases with the age of the cell; while the
young cell, in the first day of the formation of the net,
possesses only a single starch vesicle, on the second at
most 2, on the third 3—5, on the fourth 5—10, vesicles,
the full-grown cell, about three weeks old, displays
several thousands of them, which give the Water-net a
beautifully punctated appearance,* and were wrongly

* Vaucher, ‘Histoire des Conferves d’Eau douce,’ 1803, described the
starch vesicles as graizs brillans, and considered them the male organs of
Hydrodietyon.

REJUVENESCENCE IN NATURE. 173

imagined by Areschoug* to be the rudiments of the active
germ-cells. When the cells are less perfectly developed,
the internal mucilaginous layer exhibits a reticulated ap-
pearance, forming very irregular green meshes on a yellow
ground. Whether, in this case, these are real reticu-
lated perforations, or the chlorophyll merely is contracted
within a continuous mucilaginous. layer, I shall leave
undecided. I mention this reticulated structure in order
to observe, that although it vanishes subsequently on the
more vigorous development of the cells, it is a normal
occurrence in the young cells, and commences even on
the first day of existence, by the green contents, originally
uniformly filling up the cell, contracting into a broad green
zone, which divides more and more in the succeeding
days, and so gradually passes into the formation of a
many-meshed net, a phenomenon which at the same time
indicates that the separation of the contents into the
various layers occurs in the very earliest youth of the cell.

A. The fluid, which fills up the interior of the three-
fold sac. It is of watery consistence, and no further
organic parts can be distinguished in it.

Thus, then, it is shown that the cell-contents form a
far more perfectly organised body than is ordinarily
imagined ; that they exhibit a multiplicity of differences
of organisation, which are no less important than the
differences of the cell-membrane, to which vegetable
anatomists have hitherto almost exclusively paid attention,
and which after all may themselves be merely results of
special peculiarities of the contents. As the modifications
of the structure of the cell-wall have been used, not only
for the distinction of the different kinds of tissue, but
even for the characterisation of the great divisions of the
Vegetable kingdom, so must the differences of the organi-
sation of the cell-contents, which have hitherto found

* Areschoug, ‘De Hydrodictyo Utriculato,’ “Dissert. Bot.,’ Lunde,
1839, Linnea, 1842, and Hassall’s ‘Fresh-water Alge,’ 225.

174 THE PHENOMENON OF

some application only in systematic Algology, as generic
characters,* be taken more and more into account.
Among the essential parts of the organisation of the
cell, is also the cell-nucleus or cytoblast, as it were a cell in
the cell, mostly containing in its interior again a nucleolus
(nuclear corpuscle, kernkörperchen). Nägeli’s extensive
researchest have demonstrated its occurrence in all
divisions of the Vegetable kingdom; only in particular
families of the Algee, as, for example, in the Palmellacecze, f
Chroococcaceze, Oscillatorinex, and Nostochinee, as also
in the large-celled Cladophore, and the unicellular
Alge, with unlimited growth of the cell (Vaucheria,
Codium, Caulerpa), no trace of a nucleus has yet been
discovered. Schleiden$ was the first to direct attention
to the importance of the nucleus and its relation to the
original formation of the cell. It undoubtedly originates
before the cell is outwardly defined; it is thus, in the
truest sense, a central organ, around which the vital
circle of the new cell is drawn.|| Originally it is always
situated more or less in the centre of the protoplasm ;§
by the subsequent development of a cavity in the in-
terior of the cell, it mostly becomes parietal, ©. e.,
imbedded in the layer of mucilage forming the internal

* See especially the family of the Zygnemacex, as also the Desmidiacee,
in which latter Nägeli has founded’ the more accurate diagnosis of the
genera in part upon the condition of organisation of the cell-contents,
(‘ Hinzell. Algen.,’ p. 100, t. vi-vili).

T ‘Zeitschrift. fur Wiss, Botanik,’ 1844, pp. 34-68. Transl. in Ray
Society’s publications, 1845, pp. 215-246.

{ In the genus Chlamidococcus, at least allied to the Palmellacex, (see
above, pp. 188 and 158), I have found in the centre of the cell a vesicle filled
with fluid, doubtless corresponding to the nucleus, surrounded and con-
sequently hidden by the oily (?) red colouring matter of this plant. In
te et the true Palmellace® there is a chlorophyll-vesicle in the centre of
the cell.

§ ‘Beiträge zur Phytogenesis,’ ‘Muller’s Archiv,’ 1838. Transl. in
Scientific Memoirs, vol. i, p. 281.

|| Vide, in reference to this especially, Nageli, ‘Ueber Entwicklung des
Pollens,’ (1842), and Hofmeister, ‘Enstehung des Embryo der Phanero-
gamen,’ (1849).

4] H. von Mohl, ‘Bot. Zeit.,’ 1846, p. 76. (‘ Ann. Nat. Hist.,’ xviii, 3.
—A H)

REJUVENESCENCE IN NATURE. 175

investment of the cell; thus in the filaments of the
genera Gdogonium and Ulothriz. It then often aes
surrounded by radiating streaks of mucilage, e. g., i
the embryo-sac of the Phanerogamia,* frequently oe
the starting point and centre of the circulation occurring
in such threads of mucilage, as is seen most beautifully
in the hairs of the stamens of Tradescantia;} or, finally,
it 1s itself carried along by the current, as is the case in
the Characee (where, however, it soon vanishes) and
Vallisneria.t More rarely the nucleus retains its central
position in the hollow cell also, when it appears as if
suspended in the centre of the cell by an apparatus of
radiating mucilaginous threads, as may be seen most
beautifully in Spzrogyra.§ In Zygnema it is held in the
centre of the cell by a strip of mucilage, which connects
two large starch-vesicles, these being again connected
with the wall of the cell by radiating mucilaginous
filaments, rich in chlorophyll. The Fucoidez|| also
exhibit a central nucleus, occupying the middle of a
delicate circulation-network. In Closterium the nucleus,
with its colourless mucilaginous envelope, is maintained
in the centre of the spindle-shaped cell by the green
lamellz of contents, arranged radiantly around the long
axis of cell, which lamellz are interrupted by it in the
middle of the cell. In many cases it seemed to me to be
surrounded, as by a band, by a cavity containing water.
In the cells of the delicate links of the antheridium of
the Characez, lastly, the nuclei are so large that they
occupy the greater part of the cell, sometimes occupying
the centre, sometimes pushed a little to one side.

* Vide Hofmeister, 1. c., t. ii, f. 18-26.

+ Meyen, ‘Pflanzen Physiologie,” ii, t. viii, f. 6-10.

+ Ibid., f. 2, and Schleiden, ‘ Grundzüge,’ p. 293, f. 91, ‘Principles of
Sc. “Botany, p- 93, f. 95.

$ Schleiden, ‘ Grundz.,’ ii, t. i, f. 7; ‘Principles,’ t. i, f. 7.

|| Nägeli, ‘ Zeitschrift,” 1844, p. 43, t. ii, f. 1-3. (Sphacelaria scoparia
and Zonaria Pavonia.) Transl. in Ray Soc. public., 1845, p. 222, pl. vii,
fig. 1-3.

°T Vide Focke, “ Phys. Studien.’ t. iii, f. 11 and 26; Nägel, ‘ Hinz.
Algen.’ t.vi,c,D, E.

176 THE PHENOMENON OF

I have prefaced with these few indications of the
structure of the cell, in order to give a preliminary
characterisation of the essential parts, the behaviour of
which will be of importance to us in the phenomena of
Rejuvenescence of the cell.

II. DESTRUCTION (Entbildung) OF THE CELL.

“ The question of the multiplication of cells includes,”
says Schleiden,* “the origin and the life of the entire
plant.” With better right may we say that the examina-
tion of the Rejuvenescence of the cell includes that of the
whole life of the plant ; for there are plants which run
through their entire vegetative vital development in one
single cell, consequently without multiplication, but not
without partial Rejuvenescence of the cell. The multi-
plication of cells itself is nothing else than a phenomenon
of Rejuvenescence of the cell. All Rejuvenescences in
cell-life, however, are connected with a more or less
deeply invading destruction of the already consolidated
parts of the cell standing in opposition to a progressive
development. These phenomena of undoing and stripping
off the proper earlier structures of the cell, are what
we have here to examine first of all, and this, first
in reference to the coats, then in reference to the con-
tents of the cell.

The cell-membrane, by its hardening and lamellar thick-
ening, soouer or later becomes an obstacle to the growth
and the vital development of the cell or its successors,
the daughter-cells forming within the mother-cell mem-
brane. Numerous cells attain the aim of their life with
the complete formation of the cell-wall, as, for example,
all liber- and wood-cells, the spiral vessels, &c. In other
cells, on the contrary, we see the living process overcome
the straitening case, sometimes through mechanical

* * Grundzüge,’ i, 304 (2te Aufg.) ‘ Principles,’ p. 102.

RUJUVENESCENCE IN NATURR. 177

bursting, and sometimes through chemical softening and
solution. The cases of forcible tearing of the cell-mem-
brane are themselves of varied kinds ; we distinguish:—1,
tearing of the cell-membrane, without its being wholly
peeled off; 2, complete peeling of the cell-membrane,
skinning of the cell ; and, 3, slipping-oul of the rejuvenised
cell-structure from the old membrane.

1. One of the most beautiful examples of the tearing
of an outer cell-membrane, from its not keeping pace
with the growth of the inner cell, has been described
by Schimper* in the paraphyses of Diphyscium foliosum.
These paraphyses are composed of a simple row of cells,
which become very considerably elongated during the
completion of their development. As soon as they have
attained about half their length, the outer cell-membrane
splits annularly in the middle of the cell, like a circum-
scissile capsule; the two halves separate and remain
attached upon the links as bell-shaped or bowl-shaped
collars, while the cells continue their longitudinal growth,
sometimes opening and retracting their walls in the same
manner a second time. I have observed in certain
Confervee, especially Ulothrix Braunii,t and Zygogonium
ericetorum, conditions comparable with the process in
Diphyscium. The delicate filament of the first-named
plant is composed of a row of cells, which divide by
double horizontal division, each into four cells. The
membrane of the mother-cell of this group of four cells
tears crossways, during this process of division, into two
equal halves, which remain as short, abrupt sheaths on
the upper and lower ends of each four-celled group.
Zygogonium ericetorum exhibits the same phenomenon in
manifold repetitions, and even in cells which have ceased
to divide, and are only undergoing elongation; but the

* W. P. Schimper, ‘Recherches sur les Mousses,’ (1848,) p. 52, pl. vi,
f. 42-46.

t Kützing, ‘Spec. Alg.,’ p. 346. The above-mentioned species can
scarcely be included in the same genus with Ulothrix zonata, since it forms
only two germ-cells in a mother-cell, which, moreover, possess not four, but
only two cilia, as in the aquatic Hormidia.

12

178 THE PHENOMENON OF

persistent, double or triple, firmly connected sheaths
are not so clearly distinguishable as in Ulothrix Braunti.
The escape from the mother envelope is exhibited in a
different way in the Scytonemez (especially finely in
Arthrosiphon) and Rivulariex (especially in Schizosiphon
and Zuactis). Here it is not the individual cell, but a
whole series of cells, which breaks through the enveloping
membrane. In these genera a common coat of either
leathery or gelatinous consistence is formed around the
whole row of cells, through the cells separating only
by their side-walls (not at the joints of the link-cells.)
With the progress of longitudinal growth, this produc-
tion is repeated, so that numerous layers are formed, the
outer of which, however, are successively broken through
at the upper end, remaining as open funnel-shaped
sheaths, one fitted inside another, no longer shutting up
the upper end of the filament. In Arthrosiphon these
funnels are short, pale-coloured, and transparent, whence
this elegant genus is especially fitted to exhibit the true
structure of the compound sheaths in the said group of
Algee. In Scytonema the sheathing funnels are longer,
thinner, and very firmly connected, so that the entire
sheath assumes merely the appearance of one many-
layered sheath, clearly streaked with oblique lines,
however, in the longitudinal section. In Zuaetis, lastly,
the delicate and soft funnels separate into loose lamelle,
whence the lateral view which is obtained by the
microscope exhibits the appearance of a fibrous breaking-
up of the outer surface of the sheath. The phenomenon
of unilateral rupture of the coats is exhibited again in
another way by the remarkable genus Urococcus,* of the
family of the Palmellaceze.

The large, globular, brownish-red or blood-red cells of
this genus, throw off colourless layers of cell-membrane,

* Vide Hassall, ‘British Fresh-water Alge,’ (1845,) t. lxxx, especially
figs. 4 and 6. A form belonging to this genus, apparently standing between
U. Hookerianus and U. insignis, occurs on the elevated moors of the Black
Forest.

REJUVENESCENCE IN NATURE. 179

which, as in Gleocapsa, appear to be separated by inter-
mediate layers of softer jelly, whence arises a distinctly
concentric structure of the envelope. But the enveloping
layers of Urococcus do not retain their original form and
integrity ; not increasing themselves in size, they are
pushed off on the upper side by constantly succeeding
inner coats, being at first merely attenuated at one side,
but subsequently, as it seemed to me, actually broken
through. Since this emergence from the old coats is
always repeated on the same side, a membranous-gela-
tinous peduncle is produced, formed of cups fitted one into
another, so as to give an annularly streaked, apparently
shortly articulated aspect. The red cell, which occupies
the summit of this peduncle, sometimes divides, and
this of course produces a subsequent dichotomy of the
peduncle. Ifthe periods of the formation of the separate
enveloping layers were known, the age of the little plant,
whose history is preserved in the gelatinous peduncle,
might be determined by the number of rings. As a last
example to be included here, I may mention the forma-
tion of the so-called veil of Zonaria Pavonia.* The fan-
shaped thallus of this Alga possesses two unlike surfaces,
one of which, the outer or back surface, in reference to
the early unrolling of the thallus, is clothed with a layer
of smallish cortical-cells, these becoming coated with a
thickish membranous layer, comparable to the cuticle of
higher plants, by more active development of membrane
on the side next the surface. From these cortical-cells are
developed the fructification-cells and paraphyses, in
alternating zone-like collections (sor7). The former
originate from a division of the cortical-cells, parallel to
the surface of the thallus, into two unlike daughter-cells,
the lower of which retains the character of a cortical-cell,
while the upper emerging from the surface of the thallus,
becomes the mother-cell of the spore ;+ the latter (the

* Vide Kützing, ‘Phyc. Gen., t. xxii, 1, and Nageli, ‘ Algensyst.,’ p. 180,
t. v, f. 2, 3, 7.
{ Kiitzing and Nägeli regard this as the seed-cell itself, (* Spermatium,”

180 THE PHENOMENON OF

paraphyses) originate by similar elevation and division of
the cortical cells, which, however, is repeated several
times. he cuticle, at the same time, is incapable of
sharing in this development of the cortical cells ; it is
separated from the sorus as a connected pellicle, pushed
upward, torn up at one side and thrown over, so that it
looks not unlike the indusium of an Asplenium.

2. The complete skinning of the cell, the real peeling
off of an-outer cell-membrane, while the inner follows
the new development of the contents, is displayed in the
germination of the Mosses* and Ferns ;+ it doubtless
occurs also in the germination of all the thick-coated
spores of Algze, when they awaken from the stage of rest.
It was seen by Vaucher in the Zygnemacex,t and
according to my own researches (already mentioned
above, p. 135) it is double in Sperogyra, for two mem-
branes are stripped off in succession. The strange
skinning of the newly-formed spores of Spheroplea has
also been mentioned (p. 166). And the peculiar manner
in which the spore of Zguisetum frees itself from its
mother-cell membrane, splitting into two right-wound
spiral bands, || may be called a skinning. But we find
skinning of the cells connected not unfrequently with the
vegetative development and multiplication of the cells by
division, among the Unicellular Alge. The stripping off of
the mother-cell membrane connected with the multiplying
division of many Desmidiacez, was described and figured
by Focke@ in Closterium Trabecula. ‘The cell-membrane

Kz., “ germ-cell,” (keim-zelle,) Näg.); but Decaisne, (‘ Classif. des Algues,’
p- 26,) states distinctly that the spores escape from it by rupture, while it
remains behind upon the thallus as an empty perispore.

* W. P. Schimper, ‘ Recherches sur les Mousses,’ t. i.
+ Leszezyc-Suminski, ‘ Zur Entwicklungsges. der Farrenkrauter,’ (1848,)
t.i.

1 Vaucher, ‘ Hist. des Conferves d’Bau douce,’ t. iv, f. 5; t. vi, f. 4.

§ (See Pringsheim, Transl. from the ‘ Flora,’ in ‘Annals of Nat. Hist.,’
2d ser., vol. xi, p. 210.—A. H.)

|| Mohl, (‘ Flora,’ 1833, p. 45, and ‘ Verm. Schrift.,’ p. 72, t. ii, figs. 6, 7),
represents these bands as left-wound, an error which probably arose from
neglecting the use of the mirror in the first lithographing.

Focke, ‘Phys. Studien, p. 75, t. ii, f. xvii. According to Ralfs,

REJUVENESCENCE IN NATURE. 181

tears at both ends, and the two stick-shaped young ones
strip it off, slipping out from the two opposite sides of
the old coat, like a finger froma glove. Ihave observed
a similar skinning in Zuastrum (Cosmarium) margariti-
ferum.* In Closterium (Penium) curtum,t on the other
hand, I saw the mother-cell membrane tear cross ways, in
the middle, during the division, so that its two halves
separated and were stripped off by the two new indi-
viduals on opposite sides. I have observed a very pecu-
liar mode of the phenomenon of skinning in a new genus
of Palmellaceze, which I have called Schizochlamys.{ The
globular cells of this little Alga produce a hyaline cell-
membrane, which becomes removed to some distance
from the green body of the cell by subsequent secretion
of fluidish jelly; soon, however, (probably from endosmose,)
becoming unable to withstand the expansion of the jelly,
it splits in the direction of an equatorial circle, by a clean
lene, into two similar halves, or, if the dehiscence takes
place by two circular lines cutting at right angles, into
four similar pieces. This splitting and peeling of the
membrane, either coincides with a division of the internal
cell-mass, or it occurs without any such division. B

frequent repetition of this process the cell gradually
becomes surrounded by an accumulation of old fragments
of the membranous shell, which are held together by the
extremely transparent jelly set free. ‘The division of the
cell may be either a simple halving, in which case each
part is immediately clothed again with a hyaline cell-
membrane, or double, through the cells produced by the
first division separating immediately into two cells, without
previously acquiring a coat of cell-membrane, and therefore

Closterium Trabecula belongs to the genus Docidium; according to Nageli,
to the genus Pleurotenium. Focke, moreover, confounds at least two
distinct species of this genus under his Closterium Trabecula.

* Focke, 1. c., t. ii, fig 17, represented in division, but without notice of
the skinning.

+ Ralfs, ‘Brit. Desmidies,’ t. xxxii, f. 9.

{ Kützing, ‘Sp. Alg.,’ p. 891. Perhaps Hassall’s Svrospora virescens,
(Hass., t. Ixxviii, f. 8, @,) may belong to my Schizochlamys gelutinosa,

182 THE PHENOMENON OF

without skinning.* I have also seen a skinning of the
cell by irregular tearing and exfoliation of the outer
lamellae of very much laminated cell-membranes, ex-
hibited very beautifully in Chroococcus decorticans,t a
species very closely allied to Ch. rufescens (Nag. ‘ Einz.
Alg., t.i, a) and Ch. turgidus (Kütz. ‘tab. phyc.,’ 6).
I have also met with irregular bursting and peeling off
of the outer coats of multicellular families, or sometimes
also of isolated cells surrounded by manifold coats, in a
Gleocapsa, with dark purplish-brown coats, standing
near to Gl. Magma (Kitz. ‘tab. phyc.,’ 22); also in
Gleocystis vesiculosa, Näg., and Gl. ampla (Gleocapsa,
Kz.). Nägeli also figures a skinning in Pleurococcus
miniatus (1. c., t. iv, E. 6).

3. The slipping-out, or better, the expulsion from their
old membranes of rejuvenised cells, intimately trans-
formed, and passing into a renovated development, is dis-
tinguished from the skinning of the cells just examined,
in that the cell-membrane is not stripped off the resting
body of the cell, but, vice versd, the coat, remaining in
its place, drives out the contents separating from it, after
the latter have burst the envelope. This occurs parti-
cularly in the cases where the cell discharging its con-
tents is fixed, either by an independent attachment, or
belonging to tissue, by connection with its fellows. In
free cells no accurate limit can be drawn between
skinnning and slipping-out of the contents. Slipping-out
is the ordinary process by which the reproductive cells
of many Algz, Lichens, and Fungi, emerge from their
mother-cell chambers; if they are active, it is at the same

* Vide plate ii, and the explanation.

{ The cells of this new species are smaller than in its two allies, from 75
to 4 willim. in diameter, and verdigris green; the colourless membranous
layers tougher, more clearly distinguishable. When the divisions of the
cell succeed rapidly, the thin coat exhibits but four layers; when the
division is intermitted, numerous (8—10) layers of membrane are found,
often appearing thickened on one side, and finally exfoliating irregularly.
Tincture of iodine colours the contents reddish or yellowish-brown, the
coats golden yellow. It occurs on the walls of the tufa caves near St. Aubin
on the Neunburger Sea.

REJUVENESCENCE IN NATURE, 183

time a “swarming-out,” in which the peculiar motion
begins sometimes during the birth, or even before the
birth, inside the parent envelope. ‘The orifice in the
mother-cell membrane, as in “skinning,” may be either
an irregular rupture or a regular dehiscence. The con-
tents left in the old coat are either undivided, entering
upon their altered destination as a whole, or divided,
i. e. separating into several cells in the transition to a new
course of life; the cells coming to light are sometimes naked
gonidia, sometimes spores already clothed with a new
cell-membrane. We have already had cause to examine,
in detail, many of the examples to be cited here, so that
it suffices merely to recall them to recollection. A single
active gerin-cell frees itself from its chamber. by dehis-
cence of the latter at the apex in Vaucheria (vide supra,
p- 163); in Gongrosira Sclerococcus* by tearing at the
apex or the side, according as the mother-cell is an
apical-cell or a link-cell; by bursting of the back-wall of
the cells of the circular thallus adherent by its lower
surface, in Coleochete scutata (vide supra, p. 141); by a
lateral splitting of the cells of a shrubbily-branched thallus
in Coleochete pulvinata (p. 142), Chetophora, Stigeoclo-
nium, and Draparnaldia (p. 138); by annular dehiscence
at the upper end of the cells in Edogonium (pp. 141 and
162); by disarticulation of the laterally attached bristle-
cells and breaking-open of the septa separating them from
the link-cell of the filament in Bulbochete (p. 141). A
single resting cell is set free from its coat (the perzspore),
and this by dehiscence at the apex, in Chantransia
(p. 143), Chroolepus (?), and the Fucoidez in the extended
sense.t Two active germ-cells slip out from a mother-
cell, breaking through it laterally, in Ulothrie Braunii

* Observed in July, 1847. The almost globular gonidia possess four
cilia, like the allied genera Chetophora, Stigeoclonium, &e.

+ Alge pycnospermee et angiospermee, Kützing. In regard to the exist-
ence of a perispore, vide the observations on Zonaria, p. 179. Decaisne and
Thuret also figure perispores visible even after the slipping out of the spores
in Fucus nodosus and serratus, (‘ Ann. des Sc. nat.,’ 1845, t.i, 0, f. 21, and
t. ii, f. 32).

154 THE PHENOMENON OF

(see p. 177) ; by breaking through the back-wall of the
cell of a creeping filament in Aphanochete repens.* I
have observed four active germ-cells expelled through a
breaking across of the mother-cell exactly in the middle
in Conferva bombycina;+ J. Agardh likewise saw four
active gonidia emerge from the cells of Znteromorpha
clathrata ;¢ 4, 8, or 16 break out laterally, in the way
described above (pp. 148, 161), from the parent-cell of
Ulothrix zonata. Chlamidococcus pluvialis (pp. 138,
158) may be mentioned again here. Four (rarely two or
eight) active cells emerge from the thick-coated, resting
(seed-) cells by irregular dehiscence of the cell-membrane,
during which operation the innermost extremely delicate
layer of the mother-cell membrane becomes detached,
partially emerging as a vesicle, and tearing subsequently
to the outer thick cell-membrane. The gonidium-like
cells gradually produce an extremely delicate membrane
over themselves in the way above described, inside which
they finally divide again into 4 (rarely 2 or 8) parts,
or, when the formation of microgonidia takes place, into
32 parts, which begin to move about inside the roomy
coat even before they swarm out. In Pediastrum (p. 161)
4, 8, 16, 32, or 64 active gonidia, enclosed by the
vesicular inner layer of the mother-cell, break out by a
tear in the old cell. A larger number of active gomidia,

* Aphanochete is anew genus of Als, which perhaps will have to be
united with Herposteiron, (Kz., ‘Sp. Alg.,’ p. 424,) from which it differs
through the absence of the vertical torulose branches. The bristles, which
frequently spring from the back of the cells, are not sheathed, as in
Coleochete, yet articulated in the upper part, but at the same time so
delicate that the upper portion is difficult to make out. The formation of
the pairs of germ-cells takes place by division parallel to the septa. The
germ-cells are nearly globular, possessing two cilia. 4. repens occurs not
unfrequently near Freiburg, particularly on Zilogonia, Vaucherie, Mongeotia,
Sirogonium, Conferva, &c. I observed the swarming of the germ-cells in
August, 1847.

+ Observed in October, 1847. It is remarkable that the formation of the
germ cells of this very common Conferva has been but seldom observed.

+ “Ann. des Se. nat.,’ 1846, p. 199, t. xii, f. 6. According to Thuret,
(Ann. des Se. nat.,’ 1845, p. 274), the gonidia of Ulva and Exteromorpha
possess four cilia.

REJUVENESCENCE IN NATURE. 185

formed in like manner by repeated division of the cell-
contents, break through the mother-cell of Cystococcus,*
Characium,t and Ectocarpus.t Very numerous swarm-
ing-cells, not formed by successive division of the green
contents, but by simultaneous division of the mucila-
genous layer alone, issue through irregular lateral
bursting of the parent tube in Ascidium (p. 128), Hy-
drodictyon,§ Chetomorpha erea,|| Bryopsis ;{ through
tearing open of the apex of the tube in the genus
Derbesia,** separated by Solier from Bryopsis, as also in
Saprolegnia ferax, K. (Achlya prolifera,tt Nees.) ; by a
hole formed regularly at the upper margin of the cell in
Cladophora ;t{ by a most elegant, lid-like dehiscence in
certain species of the genus Chytridium§{ parasitical on

* Nageli, ‘ Einzell. Algen,’ p. 84, t. iii, E.

T Ibid, p- 86, t. iii, D.

£ Crouan, (‘Ann. des Sc. nat.,’ 1839, p. 248, t. v). According to
Thuret, (‘Ann. des Sc. nat.,’ 1845, p. 274), the gonidia of this genus have
two cilia. :

§ In particular from these cells in which no new net is formed, (see
above, page 137.

|| According to J. Agardh. (‘Ann. des Sc. nat.,’ 1836, p. 194, t. xii,
f.1

q Ibid., 1. c., p. 200, t. xii, f. 9.

** ¢ Ann. des Se. uat.,’ 1847, t. vii. The genus Derbesia includes Bryopsis
tenuissima and Lamourouxti of authors, the fertile branchlets are shorter and
more inflated than in Bryopsis, they let the mass of the germ-cells escape at,
once by bursting at the apex, while in Bryopsis, according to Agardh, the
germ-cells escape singly by a small, lateral, nipple-like and outwardly pro-
jecting orifice. The germ-cell of Derbesia possesses a wreath of cilia, ike
those of Gdogonium.

tt Vide Unger, ‘Einiges zur Lebensgeschichte der Achyla prolifera,’
(‘ Linnea,’ 1843, p. 129, t. iv.) I have repeatedly observed the mode of
origin of the gonidia from the mucilaginous layer of the fructifying end-
cell ;°I could only detect a single, short cilium, while Thuret describes two.

{££ According to observations on Cladophora glomerata, (June 1847), and
fracta, (August 1847). Meyen observed the birth of the active spores in the
former species, (‘ Nov. Acta.,’ t. xiv, li, p. 445, t. xxvii, f. 5, 6.) In regard
to the number of cilia my observations agree with Thuret’s; I found two in
C. glomerata.

§§ The Ohytridia form a new genus of unicellular, parasitical Alga, or, if it
be preferred, of aquatic Fungi, related to Saprolegnia about as much as
Ascidium is to Bryopsis. The entire plant is composed of a single, balloon-
shaped cell, which penetrates into the Algee upon which it grows by a more
or less developed root-likc base. The inflated portion of the cell is filled
with colourless mucilage, from which are formed, not through successive

186 THE PHENOMENON OF

other Alge. In several of the last-named genera, an
active whirling motion of the gonidia occurs, even inside
the mother-cell, as especially in Ascidium, Hydrodictyon,
Chetomorpha erea, Bryopsis, and Cladophora; in Der-
besia, Saprolegnia, and Chytridium, on the contrary, the
motion does not become evident until after the birth of
the previously crowded germ-cells. In Phormidium,
Lyngbya, Scytonema, Tolpothrix, Calothrix, Mastichonema
(see p. 147), and other allied genera, longer or shorter
filiform pieces of connected, motionless gonidia are seen
to emerge gradually from the sheaths common to the
whole rows of cells, and open above, breaking-up into
the separate joints after they are set free. Here, as in
all the preceding cases, it is doubtless the elasticity of the
walls which effects the expulsion of the germ-cells; the
bursting of the mother-cell coats is caused either by the
turgidity of the germ-cells, or if these do not wholly fill
the cavity (as in Ascidium, Hydrodiclyon, and Cladophora),
by increased absorption of water after previous softening
of the cell-membrane. We see the effect of elasticity
most clearly in the well-known smoke- or cloud-like
explosion of the spores in certain families of Fungi, espe-
cially in Helvella* and Peziza,t in which the rows of
eight spores are cast out with great force from the
clavate or fusiform parent-tubes, forming the thecal
membrane (Aymenium) of these Fungi.

division but by a simultaneous process, very numerous small globular germ-
cells, which exhibit a sharply-defined darker nucleus in the interior, and
possess a single very long cilium. From their want of colour, and the
activity of their motion, these gonidia resemble the most minute monads.
Their extrusion occurs either through the casting off of a lid, or through
mere tearing of a nipple-shaped point. Of fifteen different species which I
have observed in the vicinity of Freiburg, Ch. olla is the largest, and at the
same time exhibits the lid-like dehiscence most beautifully; it grows on the
anterior wrinkled end of the bulging parent-cells of the spores of G@dogonium
Lendsboroughii, the root penetrating into the folds and attaching itself to the
spore. The free inflated portion of the cell is ovate, with the lid somewhat
thrown up at the edges and apiculated like a short nipple in the middle.
The germ-cells are about si; millim. in diameter.

* Vide Bulliard, ‘Champignons de la France,’ ii, t. 242.

+ Ibid., t. 154, and Corda, “Icones Fungorum,’ iii, t. vi, 95. (Also
Tulasne, ‘Ann. des Sc. nat.,’ 3e sér., xvil, 72.)

REJUVENESCENCE IN NATURE. 187

I will add to these examples of the setting-free of the
cells destined for the Rejuvenescence from their “ super-
annuated” envelopes, a few very strange examples of
normally imperfect release of the germ-cells. I have
applied the name Sciadium* to a minute Unicellular
Alga, which displays an originally obovate tube, gradually
becoming elongated into a cylindrical form, obtuse above,
and prolonged into a slender attached pedicle below.
The contents consist of uniformly green mucilage, in
which a small vesicle may sometimes be distinguished,
but only in the earliest stage of growth. The pedicle is
transparent and colourless, and secretes at its base an
originally yellowish-brown, afterwards dark-brown mass,
which gradually expands into a disk-shaped foot. When
the growth is completed, the green contents become
divided into several masses, developing into a series of
5 — 8 germ-cells ; the cell-membrane dehisces, throwing
off its summit as a finger-stall shaped cover, but the
germ-cells instead of leaving the opened tube, all collect
at the point of exit with their inferior, narrower, and
somewhat pedicellately elongated ends sticking in the
tube. Thus is produced a capitule, and by the advancing
growth of the young family, an umbel formed of indi-
viduals exactly resembling the parent individual from
which they originated. The emptied mother-cell tube
remains as the stem and support of the umbellate family,
and gradually becomes filled from above downwards with
the same yellow and reddish-brown secreted substance,
which it exhibits at its own base. The imperfect birth
of the germ-cells just described, is repeated at the transi-
tion to the third, and mostly even to the fourth gene-
ration, so that little arborescent groups are produced,

* Vide Kützing, ‘Sp. Alg.,’ p. 490, who places this little plant in the
neighbourhood of Bryopsis. To me, Ophiocytium, Nag., (‘Einz. Alg.,’
t. iv, A), seem the nearest allied genus; young specimens completely
resemble Charactum and Ascidium. The only species, Se. Arbuscula, occurs
near Freiburg on various filiform Algs, especially on Zdoyonium Lands-
boroughii and Vaucheria racemosa, in the water reservoirs of the Botanic
garden.

188 THE PIIENOMENON OF

with twice or thrice repeated umbellate ramification, till
at length the cells which form the outermost umbellules,
scatter out their germ-cells, which, after a short swarming,*
fix themselves again to be developed into ramified stocks
of new families. Nägeli has described another case of
ramification through imperfect birth of germ-cells, in the
genus Valonia.t I have observed a still more wonderful
mode of imperfect birth in Saprolegnia capitulifera.}
The formation of the fruit-clubs and germ-cells takes
place as in S. ferax, only the formation of the fruit-clubs
is never repeated by the elevation of the bottom and
growing-through of the fruit-club, but by the formation
of opposite, divergent lateral branches, close beneath it.
The fruit-club, as it is called, 2. e. the cell cut off from
the remainder of the stem, from the contents of which
the germ-cells are produced, finally opens at the apex,
and the germ-cells (40 or 50 in number) move actively
towards the mouth, in front of which they make a halt,
and, crowding up closely together, form a globular capi-
tulum. I cowld not clearly make out what really kept
them back here. But the duration of this capitule is
very short, for within only a few hours the germ-cells
leave this, their first station, shpping out of a mem-
branous coat, probably formed during their period of rest,
and swarming again for a short time after this skinning.
All that remains of the capitules is a collection of empty
vesicles, unless a few germ-cells accidentally remain
sticking in them, when these immediately begin to
germinate, sending out an acute tubular process.

It scarcely requires to be mentioned, that the phe-
nomena of mechanical release from “ superannuated”

i The swarming germ-cells of the last generation appear to possess two
cilia.

+ Nägeli. ‘ Algensyst.,’ p. 156, t. ii, f 12-14.

{ Kützing, ‘Spec. Alg.,’ p. 160 The observations were made in August
and September, 1847, on specimens from the Tili Sca in the Black Forest;
which vegetated luxuriantly on decaying pieces of Nuphar pumilum (Spenneri-
anım), but which also rapidly attached themselves upon flies falling into the
water.

REJUVENESCENCE IN NATURR. 189

envelopes obstructing the further development or reju-
venised formative action, sueh as we have here examined
in the life of the cell, are repeated in the compound
organism of the plant. Thus we see that the first leaves
and roots of Marsilia and Pilularia break through the
tissue of the proembryo, the first roots of most of the
Monocotyledons, as well as all the subsequently appearing
adventitious roots, through the cortical tissue of the stem.
The leaves of Ophioglossum break through the cellular
cover under which they are formed ; the young sporange
of the Hepatic breaks through its outer coat above,
leaving it behind as a sheath at the base; the sporange of
the Mosses tears it in two at the base, and lifts it up as
the calyptra. In like manner many Agarics tear open the
veil which encloses them in their young stage. The bark
of many trees exhibits a process of peeling off. We
find a periodical exfoliation of the periderm in Rubus
odoratus, Spirea opulifolia, and particularly distinct in
the Birch and the Strawberry-tree (Arbutus Andrachne);
a peeling of the outer liber-layers in the Vine and
Clematis; a scaling-off of the bark in the Plane, the
Apple, the Fir, &. The tuberous stem of Isoetes
scales off at its circumference. Finally, the emergence
of the embryo from the seed-coats in the germination of
Flowering plants, presents itself as a complete “slipping
out.”

We now pass to another mode, in which _ cell-
structure advancing to a rejuvenised vital activity frees
itself from the envelopes previously formed by itself,
namely, to the phenomena of chemical softening and
solution of the cell-membrane, which take place some-
times as a swelling-up, terminating in dissolution, and
sometimes as an imperceptible resorption. The change
of the cell-membrane into a more or less fluid jelly
which is at length wholly dissipated, at the advent of the
series of generations, is a very frequent phenomenon
among the lowest groups of the Alga, as, for instance, in

190 THE PHENOMENON OF

the families of the Palmellaceze,* Chroococcaceze,t Nos-
tochinex, &c., only unfortunately we are very deficient in
satisfactory investigations into these gelatinous struc-
tures, both in morphological and chemical respects. While
they were formerly mostly regarded as excretions through
the cell-walls (extra-cellular substance), Nageli,t if I do
not misunderstand the passage, explains them as outer
layers of the cell-wall itself, under the name of enveloping-
membrane (Hüll-membran).

In Gleocapsa, Gleocystis, and the other examples
mentioned above, this explanation seems to me undoubt-
edly correct, while in other cases the gelatinous mass
appears to be a real secretion on the surface of the cell-
membrane ; as, for instance, in the gelatinous envelope,
which, according to Thwaites, surrounds the conjugated
individuals of the Diatomacez, or the amorphous, very
fluid jelly in which many of the Desmidiacez live, as, for
instance, Penium curtum, the individuals of which undergo
the “skinning” above described, in their division,{ inside
this jelly. In many cases these gelatinous envelopes
appear not so much like altered and swollen layers of
cell-membrane, as coats originally secreted in a fluid-
gelatmous form. At the same time undoubted cases
show that a gelatinous softening, swelling-up, and final
solution of cell-membrane, formed of cellulose of normal
character, does really occur. My observations on the
frequently mentioned Water-net (ydrodictyon), afford
an opportunity for a minute description of such a process.
The cells of this plant exhibit, in their full-grown condition,
a tough and firm cell-membrane, about „th millim. in
thickness. By close examination, we may distinguish
three layers in this, the outermost of which is the thin-

* Vide, for instance, Palmella, (Nägeli, ‘ Hinz. Algen.,’ t. iv, p.)

T Be. gr., Gleocapsa, (ibid., t. i, B,) dphanocapsa, (t. i, B,) Gleothece,
(t. i, 6), Aphanothece, (t. i, H.)

£ “Einzell. Alg.,’ p. 13.

§ Vide supra, p. 181.

REJUVENESCENCE IN NATURE. 191

nest, the middle the thickest ; both the inner layers are
colourless, the outermost is of a pale yellow tint. When
treated with dilute sulphuric and tincture of iodine, they
exhibit different behaviour. The external layer, which
I shall call the cuticle, neither swells up evidently, nor
becomes coloured ; the inner two, on the contrary, acquire
a violet colour, more or less intense according to the
circumstances, and swell up, so that the membrane as a
whole appears twice or thrice as thick as at first. ‘The
innermost layer here becomes thicker than the middle
one, which was previously the thickest, at the same time
becoming folded in waves on its surface, and allowing us
‘to make out clearly a composition out of two subordinate
layers. If strong sulphuric acid is applied, the circum-
ference of the entire cell is perceptibly contracted; the
cuticle, however, does not share in this diminution of
size, but gradually separates, forming numerous wavy or
vesicular elevations, from the inner layers of the cell-
membrane, under which circumstances it can be readily
ascertained that it extends over the surfaces of articulation
of the cells, and therefore completely encloses the indi-
vidual cells, like the inner layers. A long-continued
action of strong sulphuric acid dissolves the cell-wall, the
cuticle however appearing to withstand this longer. A
swelling-up of the cell-membrane, exactly similar to that
produced artificially by acids, takes place in the natural
course of life of the Water-net, at the period of
propagation. As soon as the germ-cells are formed in
the interior, the cell-membrane appears thickened, and
its internal surface somewhat wavy. While the spores
are commencing their originally very slight movements,
the cuticle tears. From this time those cells in which
large gonidia, destined to form new nets, have been
produced, are distinguished from those which contain
small gonidia destined to swarm out.* In the former,
namely, the entire cell-membrane expands very perceptibly
and uniformly in the course of a few minutes, the cuticle,

* Vide supra, p. 137.

192 THE PHENOMENON OF

now too small, being peeled off in little strips By this
expansion the cell-membrane is removed to a little dis-
tance from the layer of macrogonidia previously lying close
upon it, and these, now gaining space, commence a more
active tremulous motion, soon uniting together into a
new net inside the mother-cell membrane, and in this
combination settling to rest. The young net enclosed
by the membrane of the mother-cell now grows rapidly,
the mother-cell membrane continues to expand for a
short time longer, becoming at the same time continually
less distinct, and by the second day it has entirely
vanished. In those cells, on the other hand, containing
microgonidia, the cell- membrane does not expand unl-
formly, but forms a bulging enlargement, at one or other
part where the cuticle is torn, which bursts and lets out
the microgonidia in a dense swarm, moving most actively.
Emptied by the swarming out, it remains unchanged,
and is for a long time distinguishable as an empty coat,
a proof that the more rapid solution of the net-forming
mother-cell is produced by internal causes. Other cells
which do not arrive at fructification, never exhibit the
process of softening. While, under favorable circum-
stances, the entire process of vegetation of the Hydro-
dictyon net is completed in 3—4 weeks, in which
time the individual cell is enlarged (longitudinally) more
than a hundred-fold (sometimes even 4—5 hundred-
fold),—other nets, in unfavorable conditions, exhibit
a slower development, vegetating for four or five months
without attaining the normal dimensions. In the cells
of such retarded nets, never attaining to fructification,
we observe a proportionately thicker and very firm cell-
membrane, which exhibits in the sectional view a delicate
transverse striation (pore canals?) which I never could
detect in normally developed cells.*

* (This striation seems analogous to that sometimes occurring in liber-
cells of certain Phanerogamia, as first described by Schacht. See a notice
on this point (by the ge aaa]! in the ‘Journ. of Microsc. Science,”
vol. i, p. 233, (1853.)—A. H

REJUVENESCENCE IN NATURR. 193

The contents of these cells mostly exhibit an abundant
formation of oil, of which scarcely any perceptible trace
otherwise occurs, and they decay finally with various
phenomena of dissolution ; but the cell-membrane is still
firm and uninjured after the death of the contents. All
this proves beyond doubt the relation of the softening and
solution of the membrane to the processes of Rejuve-
nescence in the contents of the cell. A similar softening
and solution of the cell-membrane occurs in Botrydium*
at the period of formation of the germ-cells. The vesicle,
of a leek-green colour at the time of the vegetative com-
pletion, assumes a sea-green colour at the period of
ripening, which results from the thickening and clouding
of the cell-membrane which occurs at this time; the
previously indistinguishable laminated structure of the
membrane becomes clearly visible about this time, and
the cell-membrane, become limp by softening, collapses,
finally melting away, and leaving the germ-cells behind
upon the ground. The solution and resorption of the
parent-cell membranes, so frequently occurring in the
tissues of plants, which have been most accurately observed
in the formation of the spores of the Ferns and Mosses,t
as also in the formation of the pollen of the Phanerogamia,
undoubtedly depend upon similar processes. The gela-
tinous thickening of the membrane of the mother-cell
mentioned both by Nägelif and Unger,$ is probably
intimately connected with the quickly succeeding re-
sorption.

We may also again call attention here to analogous
occurrences in the compound structure of the plant. As
the old envelope of the individual cell becomes softened
and dissolved, and vanishes imperceptibly, in the trans-

* Vide supra, p. 128. My observations were made on the smaller
species of this genus, B. Wallrothii, Kitz.
t For the latest reseaches on this head, see Hofmeister, ‘ Fruchtbildung,
&c., der höher. Kryptogamen,’ 1850.
‘Zur Kntwicklungs-geschichte des Pollens der Phanerogamen,’ 1842.
{ ‘Ueber Merismatische Zellbildung bei der Entwicklung des Pollens,’
1844.

13

194 THE PHENOMENON OF

formation advancing to a new individualisation, so are
the compound masses of cellular tissue, which do not
themselves become rejuvenised, but enclose parts in
process of Rejuvenescence, dissolved and destroyed.
Thus, in the development of the seed of the Phanero-
gamia, the enveloping tissue of the nucleus (the axis of
the ovule or seed-bud) is first resorbed in mass, as the
embryo-sac increases in size; soon afterwards, the tissue
formed in the embryo-sac, the albumen or endosperm
surrounding the embryo, is again either wholly or
partially consumed, while the embryo enclosed by it
advances in its development inside the seed. A similar
process takes place again in germination, for in albumi-
nous seeds a softening and solution of the albumen takes
place at this period. We find examples of a gelatinous
swelling up of very thick-coated albumen-cells, at the
period of germination, especially in many Palms (Pheniz,
Manicaria, Phytelephas), and many Leguminose (Cercis,
Cathartocarpus, Ceratonia, Gleditschia, Tumarindus,
Bauhinia, Parkinsonia, Dialium, Mimosa, &c.) A similar
gelatinous unfolding of the cells occurs also in the internal
layer of cells of the testa (the epithelium of the seed), as,
for instance, in the quince and many Crucifere. The
remarkable expansion of certain layers of cells of the spore-
fruit of Marsilia, producing at the dehiscence of the fruit
the gelatinous mass issuing in the form of a long worm, on
which are attached the likewise gelatinous indusia en-
closing the individual sori, also deserves mention here.*
While the phenomena of putting off the old clothing
of the cells, examined up to this point, have displayed to
us only the external side of the process of Rejuvenescence,
the consideration of the phenomena of solution, through
which the newly-shaped products are prepared in the
contents of the cells, must necessarily carry us deeper into
the essence of Rejuvenescence. The process of solution and
transformation in the contents of the cell, invades more or

* ‘Explor. Scientifique d’Alg&rie,’ Bot., t. xaxvüii, f. 24-26; Schnizlein,
‘Iconographia.’ Marsileaces, f. 4.

REJUVENESCENCE IN NATURE. 195

less all parts of these; we see it most clearly in the
behaviour of starch or of amylon, of the fixed oils, as also
of the nucleus. There are certain products of cell-life
which furnish a measure of the age of the cell. While
the formation of chlorophyll is especially proper to the
more vigorous youth of the cell, we see in the formation
of starch and oil, in the interior of the cell, just as in the
formation of cellulose-layers upon its surface, the com-
mencement, of a limitation and quieting of the vital
activity, which marks the more advanced age, with the
distinction, however, that the preponderating formation
of cell-membrane (the process of lignification) usually
results in the permanent death of the cell, while the
filling of the cell with starch or oil brings with it a
condition of sleep, from which it may awake, under
certain circumstances, even after thousands of years, as is
proved by the well-known experiments on the germination
of grains of wheat from the tombs of the Egyptian
kings. This is more particularly true of the condition of
rest produced by formation of starch, while the formation
of oil, although frequently, is not always accompanied by
a condition of the cell in which it is capable of Rejuve-
nescence.

The formation of chlorophyll stands in inverse pro-
portion to that of starch and the fixed oils, in the cells;
while starch and oil appear in greatest abundance in the
old age of the cell, and are again either wholly or partially
destroyed in its Rejuvenescence, the green colouring
matter, on the direct reverse, vanishes in the old age of
the cells, reappearing in their Rejuvenescence. Thus the
leaves of the i ivy are coloured more or less with brownish
red in winter, and grow green again in spring. The
embryos of many seeds are green in the earliest period of
formation, but as the seed ripens, passing into the stage
of sleep, they become white, from the chlorophyll dis-
appearing and the cell becoming filled with starch or oil,
till finally, in germination, awakening to new life, they
again acquire a green colour. The contents of the spores

196 tHE PHENOMENON OF

of many Cryptogamia also include chlorophyll before
they are mature, but lose the chlorophyll, and become
yellow, brown or red,* through formation of oil, or
white,t through formation of starch, in ripening; till at
length the chlorophyll reappears in the germination.
Chlorophyll, however, this green colouring matter of
plants, so characteristic of the Vegetable kingdom in its
total manifestation, so intimately connected with the
independent} vegetative process, is one of the vegetable
substances which has hitherto been least subjected to
accurate investigation, in reference to its chemical con-
ditions, its genetic connection with other substances of
the cell-contents, and its transformations ; nay even in
reference to the shapes in which it occurs, either alone or
combined with other substances, in the cell,—so that
we are compelled to rest satisfied with these brief
indications. §

We will trace more in detail the play of formation,
solution, and reformation in the contents of the cell, in
the phenomena exhibited by starch. Schleiden calls
starch the most widely diffused substance in the Vegetable
kingdom, saying that he is not acquainted with a single
plant which does not contain more or less starch at some
season or other, at all events at the period of the rest of
vegetation.|| ‘This particular occurrence of starch at the
period of resting vegetation, in the organs in which the
plant preserves its life for a future season of vegetation,

* Vide the spores of Vaucheria, Spirogyra, Bdoyonium, Bulbochete, &e.
According to Mohl, the spores of Jungermannia contain chlorophyll in
youth (correct, A. H.). In Chlamidococcus pluvialis, the green colour
vanishes entirely in the resting generation (the seed-cells, spores) which
become reddish-brown or bright red; the active generations (gonidia), on the
contrary, gradually become green again ; (see farther on.)

Thus in the spores of Characex.

! It is absent, as is well known, from most parasitical plants, Crypto-
gamia as well as Phanerogamia.

§ (On the complex chemical conditions of chlorophyll; See Morot, Ann.
des Se. nat.,’ 3me ser., Bot., tom. xiii, p. 160.—A. EN

|| ‘ Grundzüge,’ 2te Aufg. 1, p. 150, (* Principles,’ p. 18.) Schleiden here
forgets to mention the Fungi, in which, as in the fungoid Phanerogamie
parasites, starch-formation appears to be absent. In the Phycochromiferous

REJUVENESCENCE IN NATURE. 197

during the period of rest (the winter or summer sleep),
points to the destination of starch in the economy of
vegetable life. Thus we find starch deposited in especial
abundance in tuberously thickened roots (e. g., Curcuma
leucorhiza), in the subterraneous stolons forming propa-
gation-tubers (potato), in perennial rhizomes (Iris, Arum,
Isoétes*), in subterranean buds and bulbs (Liliacez), in
the seeds of the Phanerogamia, either in the albumen
(Graminacex, Polygoneze, Chenopodiacez), or the em-
bryo (Leguminose, Castanea, sculus), and also in the
spores of many Cryptogamia (e. g., Characex and
Rhizocarpex). We find some starch deposited even in
the bark and alburnun of trees in the winter. At the
re-awakening of vegetation a new formative activity
sometimes presents itself in these same organs and the
same cells, as in the embryo and spores awakening from
the seed-sleep ; sometimes the tissue filled with starch is
merely subservient, preparing nourishment for other
organs in course of development, by the process of
solution taking place in it, dying away itself after ful-
filling this destination, as is the case in the albumen of
seeds, the tubers of the potato, the thick cotyledon of the
chesnut. But the occurrence of solution of starch is
not confined merely tosuch Rejuvenescence connected with
the changes of the seasons : I have observed it oftentimes
in the Alg® in the midst of summer, and without a
preceding period of rest, in progress of transition to
propagation, in particular in the preparatory stages of
the formation of gonidia. Hydrodictyon exhibits the fol-
lowing phenomena in this respect. The grains of starcht
forming gradually in the course of the period of growth
of the net, make their first appearance as minute globules
(or vesicles?) from jth to „th of a millim. diameter, of

Algee, (Chroococeacex, Oscillatorines, ne, &c.), both starch and
chlorophyll are deficient. (Nägeli, ‘Hinz. Alg.,’ p. 5.

* In the cake-shaped rhizome of Isoötes lacustris there is an abundant
quantity of starch, but only slight traces of oil, while in the rhizomes of the
terrestrial species there exists a preponderance of fixed oil; (see p. 200.)

+ See above, pp. 172, 192.

198 THE PHENOMENON OF

higher colour than the surrounding green mass, which
exhibits the deepest colour immediately around them. I
could not observe how these first globules, or vesicles,
originated in the green mass; the first of them displayed
itself immediately after the gonidia uniting to form a net
had passed into a condition of rest, before the cavity of
the cell had become excavated, and with each succeeding
day appeared new ones, which did not seem to have been
formed by division of the first, but to have an inde-
pendent origin. Even by the second day these vesicles
were found surrounded by a more or less evident border,
originally green, and with a somewhat sinuous or denti-
culated outline, but soon, assuming the shape of an
accurately defined, exactly circular envelope. The larger
globule originating in this way was from jth to „th
millim. in diameter, and did not subsequently increase in
size; it exhibited a yellowish or light yellowish-green
colour, the nucleus (the globule first formed) always ap-
pearing somewhat lighter than the envelope. On applying
tincture of iodine, these globules assumed a violet colour,
the nucleus seeming to me lighter, more of a wine-red ;
after a previous bleaching, by keeping a longish time in
alcohol, the envelope was coloured darker, the nucleus
paler blue-gray ; by a stronger action of iodine, so dark
that the colour was no longer distinguishable. On the
application of solution of caustic potash, the envelopes
swelled up to about three or four times the diameter,
and finally vanished entirely, while the nucleus remained
unaltered.* No lamination could be seen in the swelling
coats. Thus it cannot be doubted that the envelope,
originally infiltrated with chlorophyll, was composed, in
its fully-developed condition, of starch, while the starchy-
nature of the nucleus remains very doubtful. The
described mode of formation of the starch-granules of
Hydrodictyon appears to tally better with the theory of
Fritsche and Schleiden, that the concentrically striped

* Whether or not the nucleus would dissolve by longer action of potash
requires a repetition of the investigation.

REJUVENESCENCE IN NATURE. 199

starch-granules originate by external formation of layers
around a nucleus, than with that set up by Münter and
Nägeli, of an inner (centripetal) formation of layers.*
Examining the behaviour of these starch-grains at the
commencement of propagation, we find them disappear
in the inverse order of the origin of their parts, the
envelope first dissolving, the nucleus remaining distin-
guishable for some time, till at length this likewise
vanishes without leaving a trace. This entire process of
solution is ordinarily completed in one night ; the forma-
tion of the gonidia and the above-described softening of
the cell-membrane follows at its heels. I have observed
an exactly similar disappearance of the starch-granules
shortly before the commencement of the formation of the
gonidia in Cladophora glomerata, the cells of which, as
in Hydrodictyon, contain a great abundance of starch-

* Schleiden (‘ Grundzüge,’ 3te Auft., p. 187, Trausl., pp. 11, 567); Minter
(‘Uber das Amylum der Gloriosa superba,’ &e. ; ‘ Bot. Zeit.,’ 1845, p. 198) ;
Nageli (‘ Zeitschrift,’ 1847, p. 117). In spite of the many researches upon
starch we possess, the origin and development of the starch grain requires
a new and careful investigation, since none of the views hitherto put forth
are sufficiently supported by direct observations. The theory of centripetal
lamination is apparently borne out by the greater softness of the inner
layers, but I would suggest that the cavity of the concentric starch grains
is always so small that, taking into account the enormous enlargement which
the starch grain undergoes during the formation of the layers, an expansion
of the outer layers after their formation must be assumed, such as is
scarcely conceivable. The small starch-granules which so frequently occur
among the layers, seem to possess no cavity at all; in the sometimes single,
sometimes associated starch granules found so frequently in the interior of
chlorophyll vesicles, (I found 10—12 of them in one chlorophyll-vesicle of
the uppermost foliar joints of Chara hispida), no trace of a cavity can be
distinguished. Hence the conjecture may be admissible that the cavity in
the larger granules is not an original but a secondary phenomenon, resulting
from the disappearance of the nucleus. If the starch grains are not cells
themselves, but bodies secreted by the cell-contents, like the cell-membrane,
with which they are so closely allied chemically, thin concentrical formations
from the outside is by far the more probable. I would compare their origin
with that of pearls in the oyster shell, disregarding of course the accidental
character of the latter. As many pearls, when in contact with their shell,
become covered up by the later lamelle of the shell, structures resembling
starch grains occur in Hydrodictyon, as abnormal formations, enclosed
between the lamelle of the cell-membrane. I shall describe these more
minutely at another opportunity, together with other strange structures
occurring in the cell-membrane of Hydrodictyon.

200 THE PHENOMENON OF

granules ; also in Ulothrix, where the cells contain about
six, and in Ascidium and Pediastrum, where the cells have
only a single starch-grain. In Chlamidococcus the starch-
grains vanish at the commencement of the division of the
active cells (to be described hereafter).

The formation of fixed oil is intimately connected with
that of starch in the economy of cell-life ; its appearance,
in like manner, announces the repose of age in cell-life,
its disappearance the beginning of Rejuvenescence. We
meet with fixed oil in the cells, either mixed with starch,
substituted for it, or gradually displacing it; its occur-
rence is perhaps still more general than that of starch,
since it exists even in the Fungi and Phycochromiferous
Alge. Like starch, it is met with in greatest abundance
in those parts in which vegetation is destined to rest and
to await a future re-awakening, for instance, in tuberous
stolons (Cyperus esculentus) and rhizomes (Isoétes,* Aspi-
dium File mas.); in the seeds of the Phanerogamia,
either in the albumen (Zuphorbia, Umbellifere, Vitis),
or in the embryo (Cruciferae, Composite, Cucurbitaces,
Amygdalez, Juglandez) ; in the resting spores of Ferns,
Lycopodiaceze, Mosses,t Hepaticee,t Lichens,$ and many

* Especially in the terrestrial species: I. Aystrix, Durieu; and 7. duriei,
Bory, (‘Explor. Scient. d’Algerie,’ Bot., t. xxxvi), as also those which
grow on spots only overflowed in winter, as /. selacea, Bose., I. adspersa,
A. Braun, /. velata, A. Br., (ibid., t. xxxvii). All these contain only a little
starch but a great abundance of fixed oil, m the short tuberous stem, while
our always aquatic I. Zacustris exhibits but little oil with abundance of
starch. The oleaginous Jscé¢es all have the power of surviving a long time
in a perfectly dry condition. J. Aystrix and Duriei grow upon the dryest
hills of Algeria, in loose sand, close to the surface of the ground, where they
are exposed during eight or nine months to the greatest drought and the
most burning heat of the sun. According to the experience of Durieu, the
tubers of these species still remain alive, after having been kept dried for
five or six years; I myself have seen a specimen of Isoétes setucea revive and
vegetate after it had Jain almost two years in an herbarium.

T According to W. Schimper, (‘Recherch. sur les Mousses,’ p. 77), the
contents of the spores of Mosses are oily, without a trace of seid

+ According to Moll, (‘Verm. Schrilt..’ pp. 87, 90), the developing spores
of Anthoceros contain starch-grains, while the ripe spores contain only a
mucilaginous fluid in which oil-drops are interminel,

$ The spores of the Lichens (Mohl, ‘ Verm. Schrift,’ p. 75) often contain
an oil-drop.

REJUVENESCENCE IN NATURE. 201

Alge (e.g. Vaucheria, Spirogyra, Spheroplea, (Edogo-
nium, Bulbochete, Cylindrospermum, Rivularia, Palmo-
glea). In the spores of Characee we find a small
quantity of an often dark-yellow oil among the numerous
starch-grains ; the large spores of Marsilea also contain
a dirty-yellow fixed oil, besides starch. That the collec-
tions of fixed oil, so frequent in tubers and seeds, are at
least partially used up as nutriment, 7. e. become trans-
formed in such a manner that they may subserve the
vegetative processes over again, is a fact not admitting of
doubt, although not yet sufficiently explained in its chemical
relations. Certain experiences of the Algz referring here,
not only confirm this transformation of the fixed oil, but
also indicate that the necessity of a condition of rest for
most seeds, as well as for most tuberous and bulbous
plants, is connected, at least im part, with this trans-
formation of the fixed oils.*

In Spirogyra the green spiral bands undergo a remark-
able change in those cells destined for conjugation ; their
regular course becomes interrupted by curvatures of
different kinds; the beautifully toothed margins vanish ;
among and beside the simple or compound starch-grains
previously present, lying in the median line of the
bands, numerous oil-drops are found, at first very
small, but some becoming as large as the starch-grains,
which are distinguished from the latter even by their
brilliancy, but still more certamly on the application of
iodine. Through the union of the contents of the con-

* Schleiden (‘Grundz.,’ 2te Auft. ii, p. 432; ‘ Principles,’ p. 462, in the
chapter on Germination) proposes the question, “ Whence does it arise that
the conditions which can and must introduce a determinate process into the
embryo, are capable of remaining a long period without action?” and he
connects with this the conjecture that the cause ‘of this phenomenon may
depend upon unknown slow chemical processes. The observations which
follow indicate that one of these pcre must be sought for in the
gradual transformation of the fixed oil through contact with atmospheric air,
which contact is brought about or else increased by drying. The well-
known phenomenon that many oily seeds, for instance those of the Cucur-
bitacex, germinate more certainly and readily after having been kept dried
for anumber of years, than in the first year, is certainly explained by this.

202 THE PHENOMENON OF

jugated cells, the continuity of the spiral bands is finally
wholly loosened, the originally green contents of the
spores become sometimes lighter, sometimes darker
brown, and appear densely filled with oil-drops of dif-
ferent sizes. I have neglected to examine whether or
not the few starch-grains present at the formation of
the spore are still retained when it is ripe; at all events,
the drops of oil form the most important part of the con-
tents. The contents of the spore appear totally changed
when it is about to germinate; the multitude of large
and small oil-drops has vanished, and the opake mucilage,
now become green, again exhibits, but indistinctly, a few
small drops or vesicles. Newly-formed spiral bands be-
come visible, as dark, very closely approximated, frequently
somewhat flexuous, oblique streaks, even before the
germinating internal cell has broken through its double
envelope.* (See pp. 135 and 180.)

The strange formation of the spore in Palmoglea, by
complete union of two vegetative cells into one single
seed-cell, has been already examined (p. 136). During
the gradual growing together and fusion of the two com-
bining cells, we may trace the formation of fixed oil step
by step. Before the beginning of the combination, the
cells are filled with finely granular green contents, in
which we see arise, during the progress of the union,
shining drops, at first very small and distant, gradually
growing larger, coming in contact and coalescing, so that
the intermediate contents almost entirely disappear, and
the complete spore appears filled merely with a mixture
of oil-drops of the most varied size. During this process
the colour of the cells changes from green to a light
yellowish-brown. Vegetative cells, with homogeneous
green contents, originate subsequently through trans-
formation and division of the contents of these oleaginous
seed-cells. The process of the new-formation which I

* Vide Pringsheim, translated from the ‘Flora,’ 1852, in * Aun. of Nat.
Hist ,’ 2d ser., vol. x1, p. 210.—A. H.

REJUVENESCENCE IN NATURE. 203

have not succeeded in seeing in its stage of transition,
must doubtless depend upon a complete internal disso-
lution of the contents of the seed-cell by transformation
of the fixed oil, preceding the division and external
assumption of new shape. Since Palmoglea does not
grow in water, but on damp rocks and moss, and in its
formation of seed coincides with the commencement of
the warm and dry season of the year, it is probable that
the gradual transformation of the oil begins even in the
period of dryness, even requires the drying up as a con-
dition of this process. That which I can only express as
a conjecture in regard to Palmoylea, is a certainty in the
following examples. Penium curtum* is a small Desmi-
diaceous plant allied to Closterium, growing in rain pools,
which are alternately quickly filled and dried up in the
changes of weather. In late autumn and in spring many
pools in the neighbourhood of Freiburg appear filled
with bright green clouds, which are formed by the social
growth, and the very fluid, widely extended gelatinous in-
vestment of the cells. The gradual ascent of these delicate
green clouds from the muddy bottom, when the little
basins of water fill again after a dry period, presents a

* See above, p. 181. Ralfs (‘British Desmid.,’ p. 109) included this
little plant, discovered by Brébisson, first placed under Clos¢erium and then
separated from it in the genus Penium, among the Zuastra, and in the
genus Cosmarium, a mistake from which a more thorough regard to the
arrangement of the cell-contents would have saved him. According to
Nageli, Penium curtum should be referred to the genus Dysphinctium, sub-
genus Actinotenium; it is very like the D. Regelianum figured by him,
(‘Hinz. Alg.,’ 109, t. vi, E), but. differs in the more numerous green longi-
tudinal bands. The pin here named is also remarkable for exhibiting the
peculiar movement of the Desmidiacex more regularly and more actively
than the other members of the family, a motion very different from that of
the Diatomacex. It is a remarkable sight to behold all the individuals in a
dish of water in a short time turn their long axes toward the light, and
thus arrange themselves in beautiful streaks in the gelatinous mass.
Observation with the microscope shows that it is the younger half of the
cell, distinguishable as such for a long time after division, which here
turns toward the light. For those who believe in the animal nature of the
Desmidiacex, I will add, that the cell-membrane of Pexium is totally
destroyed by a red heat, so that it is not a siliceous lorica; on the other
hand, it remains uninjured when boiled in solution of potash.

204. THE PHENOMENON OF

beautiful and peculiar aspect. ‘lhe formation and sub-
sequent solution of the oil, as I have observed it in these
little plants, is not connected, as in the preceding exam-
ples, with formation of spores, but occurs in the vegetative
cells ; the formation of seed, in Penium curtum, doubtless
taking place through conjugation, has not yet been
observed. In fresh vegetating individuals the contents
of the longest cell, somewhat constricted in the middle,
exhibit the following character : in the middle of the cell
exists a rarely clearly distinguishable nucleus; in the
middle of each half a large globe, which Nageli calls a
chlorophyll-vesicle, but which I found completely filled
with starch, at least certainly in older cells. 'I'he rest of
the light-green general mass of the contents is traversed
in each half by ten to twelve darker green somewhat granu-
lated longitudinal bands, which, seen from the apex of the
cell, appear like thickish plates, arranged radiantly around
the long axis, and united in the middle. If Pentium
curtum 1s cultivated for a length of time in a dish of
water, all the individuals undergo a peculiar alteration,
some sooner, some later. ‘The dark-green longitudinal
streaks become indistinct and irregular, till at length
they disappear, while a quantity of lighter and more
brilliant globules appear, which, increasing in size, wholly
displace the green contents of the cell, so that the pre-
viously bright green cell at last assumes a pale, dirty
yellow aspect. Accurate examination shows that the
brilliant globules now filling the cells are not the spores,
as might perhaps be conjectured, nor starch-grains,*
but really drops of oil. ‘Tincture of iodine scarcely per-
ceptibly alters their colour, while the two large globules
of starch still existing in the two halves of the cell acquire
a dark violet tint. If oil of turpentine is applied to a
specimen not quite dried up, the globules of oil coalesce
into larger irregular drops; when more completely dried

* Meyen observed the cell of Closterium Lunula densely filled with starch
grains, (‘ Pflanzenph., iii, 437.)

REJUVENESCENCE IN NATURE. 205

up they all clearly run together, and fill the cell in an
uniform mass, by which the two starch-grains previously
hidden among the crowd of oil-drops, become very dis-
tinctly evident. With this condition of formation of oil
commences a stage of rest in the life of this little
organism ; the cells no longer increase by division; the
stimulus of light no longer produces any movement; the
gelatinous envelope vanishes without any new formation
of jelly. Unless peculiar circumstances arise, the indi-
viduals gradually die away, entirely losing their colour.
But if the water is allowed to dry up (as happens from
time to time in the natural habitations of this plant), and
the dried remains are again immersed in water, after a
shorter or longer period,* new gelatinous clouds rise up
afresh on the following day, in which are found a multi-
tude of new, again freshly vegetating individuals, con-
taining, instead of the former oil vesicles, homogeneous
green contents, in which the green longitudinal bands
are again soon to be distinguished. The multiplication
by division also soon commences again. That these
rejuvenised, revived individuals are not a brood originating
from spores, is shown by their size, which agrees with
that of the dried-up individuals. .

I have observed still more completely the Rejuvenes-
cence, caused through drying up, in the probably oleiferous
cells of the Chlamidococcus pluvialis, already many times
referred to.{

* T have not yet made out how long the life can be retained in the dried
condition, in Pentium curtum.

+ I have not unfrequently seen a filling of the old cells with drops of oil,
similar to that in Pexium curtum, in other Desmidiacex, in Diatomacex,
Pediastrum, Conferva bombycina, and exceptionally, as above mentioned, in
Hydrodictyon. In most cases this formation may end with the death of the
cell; this is tolerably certain in Pediastrum particularly.

t See above, pp. 138, 158, 184, 200. I can only indicate here the most
essential elements of the strange history of this creature, embracing a
complicated alternation of generations; to trace it completely through
all its normal and abnormal complications, would require a separate essay
and numerous pictorial illustrations. As the observation of the many
interesting phenomena afforded by this plant is by no means difficult,
and as it is desirable that these observations should be repeated by many

206 THE PHENOMENON OF

Normal fully-developed cells of this multiform creature,
sometimes like a plant, sometimes like an animal, present
the appearance of globules, from 4th to „th millim. in
diameter, with a thick tough cell-membrane, and
granular-punctate, opaque contents, sometimes of brown,
sometimes (at other periods or in other localities) bright
red colour. In the mass of the dark contents lie hidden
several other structures, which at this period are com-
pletely concealed, namely 4—6 starch-globules, of ith,
or at most „th millim. in diameter, in which, as in those
of Hydrodictyon, a nucleus and an envelope may be
distinguished, acquiring a dirty violet colour with iodine,
the nucleus becoming rather redder. Sulphuric acid
causes a considerable swelling up of the coat. ‘There
also appears to exist in the centre of the cell a large,
very delicate nuclear vesicle, which, however, is so
covered up by the rest of the cell-contents, that it can
only be very indistinctly perceived, and cannot even be
clearly displayed when the contents are squeezed out.
When these resting globular cells are placed in water,
they give birth, in the way already described (p. 184),
to four gonidium-like swarming cells. Even before the

persons, I venture to draw attention to the very wide diffusion of this
species. Von Flotow, the discoverer of Chlamidococcus pluvialis, found
it, in the year 1841, in a shallow hollow in a granite slab forming the
foot-bridge across the Frosch-graben, near Hirschberg ; subsequently (1846)
also in excavations in the granite rocks of Opitzberg, near Hirschberg,
where the rain-water collected. Dr. Mettenius found it recently, also, in
cavites of granite rocks, at. Harlass, near Heidelberg. I found it for the
first time in shallow hollows of horizontal sandstone slabs, on the walls
of several bridges near Freiburg, in February, 1848, accompanied every-
where by a beautiful Rotifer (Philodina rosea), and in one shady spot
associated with Mastichonema pluviale. The pastor Brunner found it last
winter in the district of Donaueschingen, in several churchyards, in the
basins cut to hold holy water of the (sandstone) gravestones, and also in
the iron vessels fixed on the tombs for the same purpose. I found it at
Neuenberg, in Switzerland, in the years 1844 and 1848, in the hollows
formed by ancient denudations of the calcareous rocks bordering the lake,
and in this place of especially bright red colour. Kützing indicates it also
from Bohemia (according to Corda), France (Brébisson), and Scotland
(Greville), as he regards Hamatococcus Corda, Meneghini, and Protococeus
nivalis, Grev., (Scott, ‘Crypt. Flora,’ t. 231,) as the same plant as Hamato-
coccus pluvialis, V. Flotow, on which point I do not yet venture an opinion.

REJUVENESCENCE IN NATURE. 207

commencement of the division of the contents by which
the latter are formed, a change begins in the colour of
the parent-cell, the red colour retreating to some extent
from the periphery, and a yellow (sometimes rather
greenish) border forming round the deep red inner mass.
The young swarmers also, for a short time after they
issue out, have only a narrow yellow rim round a dark
red middle. During the two to three days’ period of
movement and growth of these swarming. cells, —in which
they grow to about four times the original size, changing
their obtusely ovate form, at the same time, to a re-
versed pear-shaped, apiculated shape, and forming a
delicate enclosing membrane (p. 158),—important new
changes take place in the contents of the cells. The red
colour becomes more and more concentrated into the
middle of the cell, so that a sharply defined bright red
nucleus is formed, in the interior of which a lighter space
is often clearly perceptible, corresponding to the nuclear
vesicle above mentioned, around which the red colouring
matter forms a covering, mostly complete, but sometimes
imperfect and interrupted. The rest of the cell-contents
have become a brilliant green, and in them may be
clearly distinguished the above-mentioned starch-globules,
as well as many more smaller green granules. The
ciliated point of the cell, often drawn out like a beak, is
colourless. This first moving generation is succeeded by
a not yet accurately determined number of similar active
generations, populating the water for some weeks, and
often giving it a bright green colour, till at length
universal rest recommences, and the cells sink to the
bottom or attach themselves to the sides. The transition
from one active generation to another takes place through
a transitory resting generation of extremely short duration.
The full-grown swarming-cells finally come to rest within
their wide shirt-like envelope, and almost simultaneously
divide into two cells, which, without becoming active,
divide again into two cells. Thus, within the mother-
envelope are produced four daughter-cells (more properly

208 THE PHENOMENON OF

grandchildren), which begin to move soon after they are
completely formed, and, tearing open the delicate en-
veloping vesicle, part company. The whole of this
process of development is gone through very rapidly,
being completed in one night and the succeeding
morning. The second active generation, thus formed,
resembles the first, with the single distinction that the
active cells are green from the first, and have a smaller
red nucleus in the interior. The subsequent active
generations bear a general resemblance to the preceding,
but many modifications present themselves. Thus, for
example, we not unfrequently see the full-grown swarm-
cells assume strange two-lobed, or even four-lobed, shapes,
beginning to divide before they come to rest; or some-
times a transverse construction and bisection of the cell
takes place, caused by a partial protrusion of it from the
loose shirt, &c. The formation of cavities (Vacuoles) is a
pretty constant phenomenon in the later active gene-
rations, and there may be several of them eccentrically
placed, with the red nucleus retaining its central position,
or a single central vacuole, causing a lateral displacement
of the red nucleus. If water-cavities of this kind displace
the green mucilaginous layer entirely, in places, so that
they come in contact with the primordial utricle, the
form is produced which Von Flotow called Hematococcus
pluvialis lacunosus, and has represented in pl. 25, figs.
69 and 70, loc. cit. The red nucleus often becomes very
small in the last generations, so that it very much
resembles, especially when rendered parietal by the
formation of a central vacuole, the red corpuscle occurring
in the gonidia of many genera of Algz, belonging to
very diverse families, and which was called the “ eye”, in
the Volvocineze, by Ehrenberg.*

* I have observed an “eye” of this kind in the swarming gonidia of
Hydrodictyon, Ulothriz zonata, (vide Kütz., ‘Phyc. gen.,’ t. Ixxx,) Uloth.
Braunii, K., Hormidium variabile, K., Draparnaldia, Stigeoclonium, (in
several species,) Chetophora, (likewise many,) Coleochete pulvinata, Clado-
phora glomerata ; therelore in genera belonging to five different families, not

REJUVENESCENCE IN NATURE, 209

A total disappearance ofthe red colour not unfrequently
occurs. In the later stages of the cycle of generations
arrives, finally, the formation of microgonidia, already
mentioned (p. 138); many individuals, instead of pro-
ducing four daughter-cells, undergoing further division,
so as to give birth toa brood of sixteen or thirty-two minute
cells, which, before they separate, form a mulberry-like
body, but, separating at length, commence a very active
swarining inside the parent envelope, terminating in the
rupture of this coat, and the rapid dispersion of the
little “swarmers.” These are of longer shape than the
large “swarmers,” only about „th, rarely th millim. long,
of yellowish or dirty yellowish-green colour, with reddish
ciliated points.* They do not exhibit increase of size,
like the large “swarmers,” never become coated with a
perceptible and loose membrane, and have no further
power of propagation. Most of them die after they have
settled to rest, dissolving away; others turn into little
red globules, and it is doubtful whether they can grow up
to the normal size. If we now further examine how the
cycle of active generations is closed and carried over to
the resting vegetation, we find that the large “ swarmers”
of the last active generation, when their growth is
completed and they have attained the stage of rest,
instead of dividing again, remain undivided, assume a
perfectly globular form, and in the course of a few days
become clothed by a thick, closely applied cell-membrane,
while the earlier, loose, distant membrane gradually
disappears. The contents, which at the commencement
counting the Volvocinee (Volvor, Pandorina, Botryocystis Morum?.) In
the genus Chlamidomonas there are species with and others without the red
point. The red point seems to be absent in Vaucheria, Gdogonium, Bul-
bochate, Conferva bombycina, Aphanochete, Gongrosira, Ascidium, Characium,
Sciadium, Pediastrum, Apiocystis, Dictyospherium, Tetraspora, Protococcus
viridis, Gleococcus. The minute size and light colour may have caused it to
have been overlooked in many cases.

* Hematococcus pluvialis porphyrocepalus, Von Flotow, 1. c., p. 469,
t. xxv, f.74. I must observe, however, that I have never observed the
hammering movement of the slender red anterior end, there described; the

motion was effected, as in the large swarmers, by two cilia, which became
visible by the application of tincture of iodine.
14

210 THE PHENOMENON OF

of the rest were all green, except the little red nucleus,
or even often entirely green, now gradually become red
again, passing from green through many tints of brown,
or of brilliant golden green and golden brown, into red.
These globular, thick-coated cells (the same as those with
which we began) behave like seed-cells or spores, passing
into a state of perfect rest. They do not exhibit any
growth, and after the membrane has attained its proper
thickness, and the contents their red colour, no further
visible alteration takes place, so long as they are kept in
water. I have preserved them for several months in
water, without any new development taking place; on
the contrary, they at length began to be bleached and to
die away, if they were not devoured by the rapidly
multiplying Rotifer (PAxlodina roseola). A desiccation
must take place before a new cycle of generations can
begin. This is the peculiarity to which I especially
wished to draw attention here. Even a short stage of
dryness renews the Rejuvenising power of the resting
cells, and this is retained for a great length of time in
the dried condition, as might be deduced from the mode
of occurrence of the plant, and may also be easily proved
by artificial experiments. Perfectly dry specimens placed
again in water ordinarily. produce active gonidia the next
morning. I have made the most remarkable experiments
on this point, on specimens which Herr von Flotow was
kind enough to send me. Specimens gathered at Hirsch-
berg, in Silesia, in March, 1848, placed in water at
Freiburg in April of the same year, exhibited new-born
active young within 22 hours; specimens dried in 1846,
in about 32 hours; finally, original specimens obtained
from the stone slab over the Froschgrabe in 1841, after
about three days’ soaking. These last had therefore
retained their vital force during a preservation of seven
years in an herbarium.* In order to complete the main
features of the picture of the alternating generations of
this multiform creature, I must notice that, in addition

* See Von Flotow, in regard to this, 1. c., p. 500.

REJUVENESCENCE IN NATURE. 211

to the described active generations (macrogonidia and
microgonidia) and the concluding generation passing into
the spore-like condition of rest, there are other gene-
rations which, as compared with the gonidium-like and
spore-like conditions, must be regarded as the proper
representatives of the vegetative development. These
are generations endowed with quiet and slow vegetative
growth, which multiply by pure vegetative division,
unaccompanied by any swarming movement. It depends
solely upon external conditions whether the resting-cells
which I have characterised as seed-cells (spores), at once
give rise to the new active generations, or to a series of
quietly vegetating generations of cells. The former is the
case when the seed-cells are totally immersed in water ;
the latter when they occur on a spot which is at once
damp and exposed to the air,* as is the case in the
native condition, especially in the milder intervals of
winter and in the damp season of approaching spring,
but temporarily also, at all other seasons, on the margins
of the little basins inhabited by Chlamidococcus as often
as they are filled by showers of rain. In cultivating it
in the house, I have but rarely observed these vegetative
generations, while in the native stations they certainly
occupy the most important place in the alternations of
the various conditions of life, as may be concluded from
the thickness of the crusts and membranes formed
by such vegetative multiplication.f The formation and
multiplication of these vegetative generations also take
place by the division of the cell-contents, either by simple
division, the first generation being transitory, or by
double halving (apparently quartering). But the newly
formed cells do not slip out, like the young “ swarmers,”
from the mother envelope; they remain in the same place
and position. The membrane of the mother-cell appears
to become softened, expands, and becomes gradually

* Probably in such cases no perfect dessication takes place.
+ Hamatococcus pluvialis, var. leprosus, Von Flotow, 1. c.

212 THE PHENOMENON OF

drawn out to nothing, rather than regularly burst open ;
it at length vanishes in some indistinguishable way, the
daughter-cells meanwhile acquiring a tolerably thick,
closely applied cell-membrane of their own. The division
is repeated many times in this way, and as the cells all
remain in intimate contact, first small families, but by
degrees large conglomerates of cells, are produced. The
size of the single cells in these groups varies from „sth to
2th millim.; their shape is not truly globular, but partly
bounded by flat surfaces, as results from the alternating
divisions according to the three directions of space. In
this neighbourhood I have ordinarily found the colour
light brown. If ignorant of the rest of its history,
one would be led, by the form and mode of division of the
cells,to regard thesecrusts asbelonging to a Plewrococcus.*

In the same crusts occur isolated large cells, loosened
from their connection with the others, perfectly globular
in form, and appearing to divide no more, but to have
past again into the condition of resting spore-cells. They
are distinguished from the rest by their darker contents

* In this condition Chlamidococcus pluvialis exhibits such a decided
vegetable character that the advocates of the widest extension of the
animal kingdom, if ignorant of its active condition, could hardly conjecture
it to be an animal being. But even the active state of Chlamidococcus
cannot be regarded as possessed of animal life, if the swarming of the gonidia
of the Alge resulting from ciliary motion—which occurs from the Palmel-
laceee upwards to the Fucoidex, and also has its analogue in the higher
Cryptogamia, (Characew, Mosses, Ferns, and Rhizocarpex) in the move-
ment of the spermatozoids, likewise produced by delicate cilia,—is to he
regarded as a phenomenon of vegetable life, which, in spite of our ignorance
of the cause and modus operandi of this motion, does not seem to admit of
doubt, from the way in which it presents itself as a normal condition connected
with the vegetative life. Although the phenomena of motion are of longer
duration in Chlamidococcus than is usual elsewhere in the swarming gonidia
of Algze, the kind of movement is essentially the same, namely, an uninter-
rupted revolution round the long axis, combined with-an advance towards
the side of the ciliated point. In Chlamidococeus the direction is con-
stantly to the left, as in the gonidia of Bdogonium, while the gonidia of
Vaucheria, as also the oval family-stocks of Pandorina, revolve constantly to
the right. With regard to the duration of the movement, Protococeus
viridis, the active gonidia of which continue their swarming even in the
night, forms an intermediate link between the ordinary behaviour and that
of Chamidococcus and the Volvocinee.

REJUVENESCENCE IN NATURE. 213

and thicker cell-membrane. Probably the return of these
to renewed resting vegetation takes place by a passage
through the series of active generations. Every shower
of rain will wash away these loose ripe cells of the crusts
of Chlamidococcus ; carried into collections of rain-water
they will soon produce the active brood, which, returning
to rest after a few active generations, settles on the margins
ofthe little puddles, and then recurs to the resting mode of
vegetative multiplication. At least this seems to me the
normal cycle of the life of these little amphibious and am-
phibolic Algae. What we intended especially to exainine in
these, is the appearance and disappearance of a probably
oily red colouring matter in connection with the conditions
of old age and Rejuvenescence of the cells. We found this
most abundantly developed in the resting seed-cells, ar-
rived at the entire pause of the vegetation, we saw it
vanish almost entirely in the active generations suc-
ceeding one another in rapid Rejuvenescence, and en-
dowed with power of very rapid growth. ‘he red
colouring matter seems to play the same part here as we
have ascribed to the formation of oil in the instances
previously examined. Since the capability of preserving
the life in the dried condition, and the necessity of the
desiccation as a preparative for future Rejuvenescence,
may be supposed to have a similar cause in Chlamidococcus
and in other minute Alge, it is not improbable that the
red colouring matter is, in this case, either itself of oily
nature, or occurs in combination with a fixed oil.* The
mode of appearance of this in the cells testifies in favour of
this assumption to some extent, to some extent, however,

* Nägeli (‘ Einzell. Algen.,’ p. 9), likewise ascribes the red colour occur-
ring in many Palmellacee, partly as a normal (Pleurocoecus miniatus, Palmella
miniata) partly as an abnormal phenomenon (Tuchygonium, Chlorococeus,
Endococcus) to the formation of an orange-coloured oil in the place of the
chlorophyll. Probably all these have the power of retaining their life a long
time in the dried condition, in Pleurococeus miniatus, at least, I am quite
certain of it. In the crusts of Protococcus viridis, growing on walls, also,
the cells of the uppermost layers, most liable, become dried up, often acquire
a brownish-red colour, the origin of which is probably to be explained iu the
same way.

214 THE PHENOMENON OF

against it, since the red colour does not always present
the drop-form peculiar to oil. In completely red resting-
cells the entire contents (with the exception of the starch-
vesicle) appear saturated with the red colour, no separate
red drops being distinguishable ; but I sometimes found
in the dishes of water in which I cultivated the Chlami-
dococcus, resting-cells (diseased ?) in which the brownislı-
green contents were somewhat retracted from the tough
cell-membrane, and between the membrane and contents
long flattened drops of decidedly oily aspect and dark
yellowish-red colour had been formed. The connected
red nucleus, such as occurs especially in the active cells,
readily breaks up into many oil-like drops, as, for
instance, when diseased cells decay in water, as also
when they die from being dried up;* when the cell is
crushed ; as also, lastly, when sulphuric acid is applied,
which moreover gradually gives the red drops a dirty violet
colour. Oil of turpentine, on the contrary, in recently
dried-up cells, spreads the red colour uniformly through
the whole contents, or in a greater abundance at the
circumference of the cell.

The formation of oil presents itself with greater clear-
ness in the sleeping state of Chlamidomonas. Several
species of this genus, hitherto included in the Animal
kingdom, but nearly allied to Gleococcus and Chlamido-
coccus, present themselves in the beginning of spring, in
such abundance that they produce a striking green
coloration of the water; a few weeks later they vanish,
leaving no trace, and are not noticed again throughout
the whole year. I have observed the circumstances
attending this disappearance in a species which I call
Chlamidomonas obtusa.t I brought this home in the

* According to my observations, all active forms die when dried up. I
cannot confirm the existence of a Hamatococcus pluvialis atomarius, such as
Von Flotow thinks we may believe in. The preservation of Chamidococcus,
both in the dry and frozen state, certainly occurs only through the resting,
thick-walled form.

T Chlamidomonas (a name certainly sounding strangely in the vegetable
kingdom) is distinguished from the genus Chlamidococcus by the closely

REJUVENESCENCE IN NATURE. 215

swarming condition in April of last year. The large,
dark green swarmers, differing from other similar green
swarming cells by the remarkable truncation of both
ends, multiplied for some time longer, and here and there
produced very minute, paler and more brownish-yellow
microgonidia; in the course of a few weeks no more
active cells could be found in the water, the full-grown
swarmers having all gradually come to rest and sunk to
the bottom. ‘The originally longish shape of the cells
had changed into a perfect sphere with the transition to
rest ; the colour of these resting-cells, originally still green,
now gradually passed into a light yellowish-brown, at

applied membrane (not standing away from the contents) of the old swarming
cells; also by the absence of the little starch-vesicles in the interior, while,
however, as is usual in most of the Palmellacex, a single large “chlorophyll
utricle” (starch-utricle ?) exists in the interior. There is no central red
nucleus, as in the gonidia of Chlamidococeus, but some species have a parietal
red spot (an “eye”). The motion is effected by two cilia, as in Chlamido-
coccus. As in that genus, there is a growth of the gonidia during “ swarm-
ing,” which lasts over the day and night. There is also a formation of
microgonidia. The species of this genus are doubtless very numerous, but
the distinction of them among themselves, as well as from the swarming-
cells of many other Alge, is very difficult without a complete acquaintance
with the history of their lives. The new species mentioned, Chl. obtusa,
occurs in the Rhine valley, near Freiburg, in sand-pits, which are occasion-
ally almost completely dried up in summer. The macrogonidia grow during
their period of swarming, from 2 to almost 5, millim. long; they are
longish, of equal diameter on both sides, and very obtuse, almost truncated,
having a colourless place at the ciliated extremity, presenting the form of a
notch. In regard to other points, the contents are dark green, finely
granular, with a large vesicle at the posterior extremity, a roundish lighter
space in front of this, and no red point. They multiply by simple or double
halving in several successive generations. Sometimes a further continuation
of the division of the full-growu macrogonidia occurs, forming sixteen or
thirty-two macrogonidia from 45 to 745 millim. long, of ovate shape, and lighter
colour, tending towards brownish-yellow. The resting (seed-) cells are
globular, about 4 millim. in diameter, at first green, subsequently light
yellowish-brown, finally flesh-red; they have a tough, colourless, and trans-
parent membrane. Another species, Chl. timgens, occurs in enormous
quantity in the puddles of the sandstone quarries at Lorettoberg, near
Freiburg, in the month of March, in mild seasons sometimes even in
January and February. The swarming cells are smaller than in the pre-
ceding, 73; to 4 millim. long, ovate, lighter green, likewise destitute of a
red spot, and the membrane is more distinct in the old age. Increase by
double, rarely by simple halving, in the former case with decussating
sections. I have seen the formation of microgonidia in this species also, but
not minutely observed the resting stage. (See preface.)

216 THE PHENOMENON OF

the same time a number of small, sharply defined,
brilliant globules were formed in the interior, having
quite the appearance of drops of oil. In this altered
condition the Chlamidomonada remained, exhibiting
neither growth nor increase. At the end of the month
of May, in the hope of causing a renewed development,
I allowed the dish to dry up, but it was in vain; even
when I poured water on them again about a month
after, no perceptible alteration occurred. I let the mass
dry up again, and added water again in the middle of
December following ; towards the end of December, and
in the course of January, active Chlamidomonada actually
reappeared. All the resting globules had meantime
changed colour to some extent, appearing light reddish ;
the first “swarmers,” also, formed by the halving or
quartering of the contents of the resting globules, and
brought to light by a rupture of the tough coat, at first
exhibited a reddish or greenish-red colour, which only
passed gradually into pure green, the drops of oil
vanishing at the same time. Only a small proportion of
the resting-cells came to such development in cultivation
in the house; others divided, without loss of the red-
dish colour, into quietly vegetating cells connected in
groups, in a manner similar to that I have described in
Chlamidococcus ; others remained unchanged until spring,
at which time, however, I did not pursue the investigation
any further. ‘There is no doubt that future investigation
will detect in the Volvocineee resting stages for the
winter sleep, similar to those here examined in Chlami-
dococcus and Chlamidomonas.

Collecting together the phenomena of dissolution we
have been examining, connected with the Rejuvenescences
in Cell-life, we find that it results from them, that the
development and propagation of the Vegetable organism
does not consist of a bare series of formative processes,
but that processes of de-formation or “ undoing” enter as
necessary links into the course. The plant, however,
differs essentially from the animal in this respect ; while

REJUVENESCENCE IN NATURE. 217

in the interchanges of material of the animal organism,
formation and deformation intermix in simultaneous
occurrence, dissolving and newly shaping in the same
epoch, the two processes are more separated in the plant,
running into one another in periodical alternations. In
the Vegetable kingdom, as in the Animal, the nitrogenous
substances (proteine and the substances allied to it) form
the especial substratum and active medium of the vital
activity,* while the unazotised substances, rich in carbon,
play a more passive part in the organism, on the one
hand protecting, on the other limiting, narrowing, stupe-
fying, and. even extinguishing the vital force. The
animal organism frees itself from the superabundance of
carbonaceous substances, which it receives for the most
part already formed in its food, through the uninterrupted
process of respiration, in which the carbon is destroyed
(burnt) by the aid of the oxygen derived from the atmo-
sphere, and excreted in the form of gas. It is different
with the plant; it does excrete the substances rich in
carbon formed in the internal organism of the cell, out
of the cell-sap, not, however, destroying them, but depo-
siting them either as organic structures on the confines of
the cell-organism (formation of membrane from cellulose,
and the allied substances, gelin, amyloid, Lichen-starch,
&c.), or it secretes them in the interior of the cell itself
as globular, frequently laminated masses (starch or
inuline), or in the form of drops (fixed oils). The forma-
tion of the cellulose membranet is especially characteristic,
in this respect, of the plant, securing to the cell-formation
of the plant, in all cases, its peculiar separateness and
independence, however varied the mode of ultimate

* According to Payen, all young organs of plants, in their earliest stages
of development, contain a predominance of nitrogenous substances.

+ Cell-membranes formed of cellulose have hitherto been found in
the animal kingdom only in the sac-shaped envelopes of the Ascidia. See
Schmidt, “Zur Vergleichenden Physiologie der wirbellose Thier,” (1845)
Transl. in “Taylor’s Scientific Memoirs ;” Löwig and Kolliker, “De la
Composition et de la Structure des Enveloppes des Tuniciers,” (‘ Ann.
des Se. Nat.,’ 1846, p. 193.)

218 THE PHENOMENON OF

development may be. It is to thıs carbonaceous appa-
ratus of the cell that the entire structure of the plant
owes its external and internal combination and solidity ;
but it is at the same time the cause of the gradual
fixation of the product, the relative absence of motion,
which distinguishes the vegetable structure, in contrast
to the internally and externally more mobile animal
organism. It is remarkable that the most striking of all
the phenomena of motion of plants, the swarming move-
ment of the gonidia and spermatozoidia, occur in such
cells as are either yet without their cellulose coating, or
which never acquire one. Thus, consequently, the life of
the plant becomes fettered by the vegetative process itself ;
the continuous secretion of cellulose, and the thickening
of the cell-wall caused thereby, obstruct more and more
the intercourse with the outside, as in like manner the
accumulation of highly carbonized deposits in the interior
of the cell-contents obstructs the internal movement.
Thus all vital activity must at last come to a pause,
unless this entombing and suffocating process of formation
becomes opposed by a dissolving and emancipating pro-
cess. It is just this which we have sought to examine
in the foregoing pages; we have seen it make its appear-
ance at a definite period in thoseparts which are destined
to carry on or repeat the development, destroying pre-
ceding constructions, and making space for new forma-
tions, more or less interrupting the old course of com-
pletion, and often causing the life to turn off in new
directions. We have seen that the solid cell-membrane
becomes soft again, bursts, or dissolves away ; we have
seen the starch dissolved, the fixed oils vanish. But the
most important occurrence in this process of destruction
is not merely a solution of that which had become solid,
not merely a process of transformation of the substances
secreted in the formative process, into new material for
structure (¢. g. starch into dextrine and sugar), but, at
all events im part, an actual destruction (combustion)
of the highly carbonized substances present in excess,

REJUVENESCENCE IN NATURE. 219

similar to that which occurs in animal respiration. It
is well-known that in the germination of mealy seeds, as
also in the sprouting of mealy tubers, an abundant ex-
cretion of carbonic acid is associated with the conversion
of the starch into sugar, and that this, connected with
perceptible evolution of heat, is caused by a decomposition
of sugar; it is well-known that beets and carrots lose
the sugar they contain, at the period of the unfolding of
the flower, which is accompanied with abundant excre-
tion of carbonic acid; it is further known, through
Saussure’s experiments, that the internal parts of the
flower, in the delicate tissue of which the formative
process deposits the smallest quantity of highly carbonised
substances, take up oxygen from the atmosphere and
excrete carbonic acid more abundantly than any other
parts of the plant; again that the anthers are especially
distinguished among these, in which organs important
processes of solution of the tissue are connected with the
ulterior development of the pollen. In the nectaries
undecomposed sugar is excreted. There is no doubt but
all processes of solution and transformation in plants are
accompanied by excretion of carbonic acid. Observations
of the lower plants promises much more profit in this
respect. In Hydrodictyon I have seen cells in the stage
preparatory to the formation of gonidia (in which the
starch globules had already vanished), secrete gas bubbles
in unusual quantity; I neglected to examine these
chemically, but they doubtless consisted of carbonic acid,
since they were visible very early in the morning and
later in the day when the sky was overcast, and since
other nets, in a vegetating stage, exhibited at the same
moments no such evolution of gas.

The examination of the processes of solution and des-
struction, which we see introduce the new structure at
determinate turning-points of vegetable life, and which
are all characterised by absorption of oxygen and ex-
cretion of carbonic acid, leads us to the comparison of
the nocturnal respiration of plants, in which, according

220 THE PHENOMENON OF

to the facts known about it, we can in like manner
perceive nothing else than a periodical interruption of
the diurnal process of formation, by a process of deforma-
tion and de-carbonisation, although this does not so
profoundly affect the plant. It is true we cannot observe
m it any perceptible solution of cell-membrane, starch
granules, and the like, but there is no doubt of the
occurrence of an interruption in the deposition of these
structures, probably through the interposition of a process
of combustion of the materials out of which they
originate, while still dissolved in the cell-sap. It is
indeed not very adventurous to refer the lamellar depo-
sition of the cell-membrane, and the concentrically
laminated structure of the starch-grain, to this daily
periodicity of the cell-life. The great number of layers
which may be distinguished by suitable treatment in the
cell-membrane even of plants of short life (/Zydrodictyon,
Cladophora, Botrydium), is not opposed to the assumption
that they are diurnal layers, and it is imaginable, under
this hypothesis, that bright and dull days, as well as the
age of the cell and other circumstances, may effect im-
portant modifications in reference to the formation of
distinguishable layers. Annual rings, or better, annual
layers, may doubtless be demonstrated in cells of perennial
duration. ‘The Jamination described by Mohl,* in the
walls of liber-cells, for instance of Cocos and Calamus,
which exhibit the peculiar phenomenon, that the thick
and not very numerous layers, which are separated from
each other by dilute sulphuric acid, are composed of an
outer, broader, and softer, and an inner, thinner and
firmer layer, may perhaps be compared with the condition
of the annual rings of the wood of Dicotyledons, in
which, in correspondence with the reverse order of
formation, each yearly ring exhibits an inner, broader,
and looser, and an outer, narrower, and denser half. I

* «Botanische Zeitung, Ist4, p 309, 1.11, figs. $, 25, 26. (Trans.
‘Scientific Memoirs,’ vol. iv, p. 103, pl. i, 1, figs. 8, 25, 26.)

REJUVENESCENCE IN NATURE. 22]

found in the lowest internodes of the stem of the
perennial Chara ceratophylla, formed in the year pre-
vious to that in which it was examined, that the cell:
membrane, about 4 millim. in total diameter, was
composed of two .very distinct portions of about equal
thickness ; while the thinner cell-membrane of the young
internodes of the stem exhibited no such sub-division.
In each of the two portions I could make out about 10
subordinate layers, which, however, were themselves of
compound nature. The agreement of the nocturnal pro-
cess of respiration of plants with the phenomena of
dissolution, through which we have seen the transition
to distinctly new formations prepared, is confirmed by
the epoch in which the latter usually make their appear-
ance. Observation of the Algze has furnished us with
most interesting facts in reference to this. 'Irentepohl*
already observed that the expansion of the summits (the
preparation for the formation of the germ-cell) in Vaucheria
clavata took place especially in the night, and the exit
of the active germ-cell on the succeeding morning.
Ungert confirmed this, for he characterises it as a re-
markable phenomenon that the unloosing of the gonidia
of Vaucheria mostly occurs between eight and nine o’clock
in the morning. According to the statements of Thuret}
and Fresenius,$ the same phenomenon is repeated in
other Alge. I have satisfied myself in all the green
Alge with active gonidia which I have had an oppor-
tunity of observing, that the preparation for the formation
of gonidia, and particularly the disappearance of the
starch-grains mostly connected with this, begins in the
night, and in general advances so far in ove night, that
the formation of the gonidia can be completed and their
birth take place on the following morning. I will first

* According to Meyen, ‘ Pflanzenphys.,’ iii, p. 430.

+ ‘Die Pflanze im Momente der Thierwerdung,’ p. 27.

+ “C’est surtout le matin qu’on trouve le plus grand nombre de spores
des Conferves en mouvement,” Thuret, ‘Sur les Organes Locomoteurs des
Spores des Algues,’ (‘ Ann. des Se. nat,’ 1843, p. 268.)

§ ‘Zur Controverse über die Verwandlung der Infusorien in Algen,’ p. iv.

222 THE PHENOMENON OF

of all refer again to Hydrodictyon as an example. The
reason why the mode of formation of the new nets in the
cells of the old one has hitherto been so rarely and so
inaccurately observed,* doubtless arises from the time at
which this process commences. Ifa single fully-developed
net of this plant, or even mere fragments of nets, are
placed in a shallow saucer of water, we may almost cer-
tainly reckon upon finding fully-formed young nets in some
of the old cells on the next, or at all events on the second
morning, and these in cells which exhibited no alteration
whatever.t If we wish to see the origin of these young
nets, we must not lose the earliest hours of the morning,
for the tremulous movement commencing after the forma-
tion is complete, and the final union of the gonidia into
a net (see p. 137) takes place shortly after sun-rise, in
the middle of summer between four and five in the
morning, at the end of summer between six and eight
o’clock, and only in dull days of autumn, in which,
however, the formation of new nets rarely occurs, some-
times as late as ten o’clock in the morning. The
swarming out of the microgonidia of Mydrodictyon
always takes place rather later in the day than the
formation of the nets, in summer usually between seven
and nine, in autumn between ten and two o'clock. As
the swarming lasts several hours, the active condition may
often be observed late in the afternoon (sometimes at five
o'clock in the evening).{

* The most recent treatise on this subject, by Morren (‘Mém. de l’Acad.
Roy. de Bruxelles,’) xiv, (1841,) is an almost incomprehensible tissue of errors.

r In deeper vessels of water the propagation does not commence so soon,
which is certainly explained by the diminished contact with the atmosphere,
especially with the oxygen required for the process of solution.

+ In regard to the relation of the occurreuce of the swarming-out
microgonidia to the net-forming macrogonidia, I may add that it appears to
depend, in part, upon external circumstances. Many days I saw only net-
formation, in others both net-formation and swarming, on others, again, espe-
cially on dull and rough days, formation of swarmers in unusual quantity
unaccompanied by any net-formation. It is strange that the formation of
swarmers, on the whole more frequent than the formation of new nets, has
not been more frequently observed by earlier investigators. Treviranus saw
them but did not observe their origin. (“Beiträge zur Physiol.,’ p. 81.)

REJUVENESCENCE IN NATURE. 223

The gradual changes which take place in the water-
nets preparing for fructification, converting the contents
of the vegetative cell into thousands of gonidia, must be
observed by night; but it sometimes happens that the
particular cells do not advance far enough in the dis-
solving preparation, in the course of the night, to enable
the influence of the morning’s light to complete the
formation. Such cells exhibit the earlier preparatory
stages, otherwise rapidly passed through in the course of
the night, with especial distinctness. Some thus remain
all day without any pérceptible alteration, completing the
preparatory stages in the second night, and maturing the
gonidia on the second morning.

As a second instance, I will bring forward Ulothrix
zonata, a Conferva frequent in the mountain brooks of
the Schwarzwald, descending also into the plains in the
Dreisam. The mode of growth and the formation of
gonidia have already been examined (pp. 148, 159). Ifa
little tuft of this Alga is placed under the microscope in
the morning, filaments of two characters are seen; some
(still vegetating) with parietal contents of the clearest,
brightest green, leaving the ends of the cells almost free,
in which green contents exist scarcely perceptible point-
like granules, a few small starch-globules, and a large
likewise parietal nucleus, which it is not easy to see; the
others (in the condition of fructification) of somewhat
torulose aspect, and with more concentrated, darker
contents, divided into 4, 8, or 16 masses (gonidia). We
rarely find transitions from one structure to the other,—
namely filaments with darker and more opake green
contents not yet divided, in which the fine granules are
more strongly developed, but the starch-granules either
lost, or only their little nuclei visible,—because the
transitional stages are usually passed through in the
night, and the formation of gonidia completed early in
the morning. Birth and swarming of the gonidia, which
latter mostly lasts more than an hour, may be observed
all the morning. All the mature cells are usually emptied

224 THE PHENOMENON OF

by the afternoon ; those not emptied by that time develope
no further. Once, however, I saw birth of gonidia occur
between six and seven o’clock in the evening; it was on
a very dull and rainy day in July, on which the weather
suddenly cleared up between five and six o'clock. I
have made similar experiments on many other fresh-
water Algz ; e.g., on Draparnaldia mutabilis, m which I
observed the birth of the active gonidia in March from
eight in the morning, in May from six, and the swarming
until eleven, a.m., at most. In Stigeoclonium protensum (?)
the birth and movement of the gonidia took place in May
between six and ten, a.m; in Chetophora tuberculata, in
August, between eight and two, a.m. ; in Ascidium acumi-
natum, in July, from six, a.m. to three, p.m., and even
still later, but none so late as dusk. The @dogonia
also ordinarily emit their large gonidia in the morning ;
in summer and in bright weather earlier, in winter* and
in dull weather later. Since the swarming of the gonidia
lasts several hours, in this genus, it may be often observed
in the afternoon. In Chlamidococcus pluvialis, both the
birth of the first generation of gonidia, and the production
of the succeeding generations by division of the earlier,
occurs in the morning, after nocturnal preparation, and
the same is the case in the formation of new families in
the Volvocinez, for instance in Pandorina elegans. What
we have here seen in regard to the time of formation of
the gonidia of the Alge, is true also of the vegetative
multiplication of their cells. Thus Focket has observed
that the division of the Zuastra commences early in the
morning, and has advanced so far by evening, that the
complenentary halves acquire their complete form and
full size before night. [ have made the same observation
in regard to the first commencement of the division of
the cells in Spirogyra. For a long time I could not

* Gdogonium fonticola, which vegetates all through the winter in the
holes in running brooks, and developes the longest filaments at that season,
exhibits formation of gonidia even in winter when brought into the house.

} ‘Physiol. Studien,’ (1847,) p. 47, t. ii, figs. 1, 4, 5.

REJUVENESCENCE IN NATURE. 225

succeed in finding it, although I frequently met with
cells recently divided. Not until I selected the earliest
hours of morning for the observation, and at last took
the precaution of placing specimens in spirit before sun-
rise, so as to be able to examine them at leisure later,
was I able to make out completely the process of division
of the cells in this genus. I shall describe it in the
next section of this treatise.

All these observations furnish the one common result,
that the processes of solution and deformation, the more
important as well as the slighter, occur at night, under
the influence of determinate degrees of temperature,*
while, on the other hand, they confirm the experience
that the influence of light awakens the plastic processes,
formation of substances as well as production of form, in
the plant.F A number of well-known phenomena in
the great processes of Rejuvenescence of the Vegetable
kingdom have an intimate connection with these facts. It
is well known that vegetable life awakening from the
winter sleep requires, above all things, warm, dull, and
damp days, especially the warm showers of spring, to
enable it to dissolve the winter provision of nutriment,
on which the influence of light of the increasing days
may exercise its newly-shaping force ; equally well-known
are the effects of the northern summer, which brings
many plants into flower and fruit more rapidly than our
temperate climate. It is the influence of light, increased
by the long days, which causes a more rapid development
of all products: of form, an abbreviated course of the
metamorphosis, just as we see the plants on high moun-
tains also advance with more rapid steps to flower and
fruit, through less luxuriant development of the vegetative

* More exact observations are yet to be made on this point in the Alge.
The rapid commencement of the formation of gonidia in Alge brought into
the house, doubtless depends on the slighter degree of cooling occuring
during the night indoors.

une the observations on Zuastrum mentioned in the preceding page.
I shall describe more minutely, in the Appendix, the important changes of

form which the new-born cells of Pediastrum undergo in the course of the
first day, and after a nocturnal rest, again on the second day.

226 THE PHENOMENON OF

preparatory steps, whence we find many come into flower
sooner on the mountains than in the valleys or plains, as
is the case with the heather (Calluna vulgaris), and
Parnassia palustris.* In the equatorial regions, on the
contrary, where the seasons run into one another, forming
as it were an uninterrupted spring, where, day and night
being of the same length, the most intense action of
light (through the altitude of the sun and the trans-
parency of the atmosphere) is combined with the greatest
heat and moisture, where consequently the conditions for
both factors of the process of Rejuvenescence in vege-
tation, dissolution and reconstruction, are united in high
and equal degree throughout the whole year,—there we
behold the most luxuriant development of the Vegetable
kingdom in “stock,” flower, and fruit, whose epochs of
verdure, blossom, and ripeness, more separated in other
zones, are there most intimately interwoven.

III.—RECONSTRUCTION OF THE CELL.

The process of solution and destruction in the cells,
which we have just examined, prepares for a renewed pro-
cess of construction ; the slighter and less perceptible the
process of solution, the more will the reconstruction appear
like a mere continuating formation ; the more forcibly and
profoundly it takes place, the more distinctly will the
reconstruction appear as such, as is most of all the case
in the formation of cells of propagation. All formation
of new cells, therefore, is strictly a process of Reju-
venescence of the cell; sometimes total, when the entire
contents are metamorphosed ; sometimes partial, when
only a portion of the contents pass over into new cell-
formation. If the transformation of the entire cell-con-

* Parnassia palustris flowers on the higher mountain tracts of the Black
Forest, for instance on the Schauinsland and Feldberg, in spots more than
3000 feet high, by the middle of June, while in the lowlands its flowering
does not commence until the middle or end of July.

REJUVENESCENCE IN NATURE. 227

tents is combined with a division of them, a multipli-
cation of the cell takes place, constituting the basis of the
formation of tissues in plants where the cells remain
connected together, multiplication of the individual
where they separate. The various modes of origin of new
cells, which appeared so different and irreconcileable at
first sight, now all come together finally as cases merely
differing in degree of an essentially identical process, the
re-shaping of the cell-contents. ‘The idea of origin of cells
outside, between or on the surface of existing cells,
formerly advocated by Mirbel, has proved untenable ;
neither the vegetative development nor the propagation
of plants exhibit anything but production of new cells
by transformation of pre-existing ones.* This has been
called propagation of cells, but it must be observed here,
that in the majority of cases the entire contents, z. e. the
whole active living organism of the cell, passes directly
into the new structure, so that nothing remains behind,
unchanged, of the old cell (the mother-cell), except the
passive membranous wall. The daughter-cells are there-
fore not to be considered as young produced by the
mother-cell, existing contemporaneously with it, nourished
by and gradually developed in it, but as the rejuvenised
and metamorphosed mother-cell itself; This is most
strikingly evident in those cases where the entire and
undivided cell-contents become loosened from the mem-
brane of the mother-cell, and, shaping themselves in a
different way, become anew cell: as is the case, for
example, in the formation of gonidia and spores in
Gdogonium, Bulbochete, &c., and in the formation of the

* Further researches are required to decide the relation of the in many
respects enigmatical formation of the yeast-cells, (the first cells of the
fermentation fungus,) and other analogous cases of what is termed generatio
spontanea, to cell-formation in the normal course of development and pro-
pagation of plants. (See Schleiden, ‘Grundz.,’ 2d Aufl. 1, p. 203, ‘ Principles,’
pp- 36, 569, t. i, fig. 9, and Karsten, ‘Urzengung, Botanische Zeitung,’
1848, p. 457.)

+ I cannot enter at length into the opposite view of Karsten, (‘De Cella
Vitali,’ 1844,) but I may remark that so far as relates to cell-formation it
totally contradicts my experience.

228 THE PHENOMENON OF

pollen-cells in their special mother-cells.* The whole
conception of the formation of new cells (daughter-cells)
in old ones (mother-cells), as it has grown up since first
brought forward by Schleiden,t now requires a further
elucidation, since it has been extended from the so-called
‚free cell-formation, to which alone it is perfectly applicable,
to the far more common cell-formation by division, whence
has arisen a nomenclature, to the equivocal character of
which I must here direct attention. It is a mistake to apply
the word cell sometimes to the cell with a membrane, some-
times to the cell without a membrane, and sometimes to
the membrane without the cell. Since the contents of
the cell constitute the essential part of it (see p. 155),
since it forms, before the secretion of the (cellulose-)
membrane (pp. 156—167), a separate entity, possessing
its own, essentially proper, membranous boundary (the
primordial utricle, pp. 169—173), we must call this
internal body the cell proper, unless we restrict the term
cell to the enclosing wall or chamber, and give the
internal body another name. If the name is restricted
to the internal body, we cannot, in the great majority of
cases, say that new cells are formed in the old, but
merely that they are formed out of the old, for even the
primordial utricle shares in the division, in the propa-
gation of cells by division. Therefore when daughter-
cells are said to be formed in the mother-cells, or to slip
out from the mother-cells, or mother-cells are said to be
dissolved and absorbed, these phrases must be admitted
only as conveniently abbreviated expressions, “ mother-
cell” being here used instead of maternal cell-membrane.
Finally, there are cases in which the expression, that
daughter-cells are formed in mother-cells, cannot be ap-
plied, even in this abusive sense; these are the cases
above mentioned (p. 159) of division of cells which pos-

* According to Hofmeister (‘Ueber die Entwicklung des Pollens,’ Bot.
Zeit., 1848, p. 431), the nucleus even survives this transition. i

T “ The process of propagation of cells by the production of new cells iz

their interior, is the general law in the vegetable kingdom.” (Schleiden,
‘Grundz.,’ 2 Aufl. i, p. 305, ‘ Principles,’ p. 103.)

REJUVENESCENCE IN NATURE. 229

sess no cellulose layers at all, such as we have undoubtedly
observed in the transitory generations of cells, through
which is effected the formation of the gonidia of many
Alge, (Ulothrix, Characium, Pediastrum, Cystococcus,
Chlamidococcus, &c.)

Having made these preliminary observations, I shall
endeavour to bring together, in a connected summary,
the various kinds of reconstruction of the cell, beginning
with the cases of entire metamorphosis of the contents.

A. REGONSTRUCTIUN WITHOUT DIVISION OF THE CELL.
— Here the character of the rejuvenised cell either remains
essentially the same, 7. e., the repeated reconstruction ap-
pears merely as a development of the cell advancing by
periodical Rejuvenescence, as is the case more or less
evidently in the completing development of all vegetative
cells; or the character of the rejuvenised cell becomes
different, the previously vegetative cell acquiring a
reproductive destination, at the same time being freed,
in its renewed structure, from the envelope previously
formed. In the latter case the rejuvenised cell will be
regarded as a new one, notwithstanding that, if we leave
out the inessential membrane which it throws off, it is
still the old, in reference to its essential part, the internal
body, as much as it is in the former case, only its shape
being changed. The intermediate stages to be enumerated
will show that these two cases are not so different as they
seem at first sight. We accordingly distinguish—

1. Reconstruction without division in vegetative cells,
prepared by the periodical nocturnal respiration; ex-
pressed in the lamellar deposition of the cell-membrane
(p. 220).

a. The layers of cell-membrane are intimately adherent
together, and form a firmly-united, compound cell-
membrane, the layers of which are sometimes clearly
evident, but often only to be made out by artificial
loosening by means of chemical reagents, e. g. Hydro-
dictyon, Cladophora.*

* See H. v. Mohl, ‘ Vermischte Schriften,’ t. xiii, f. 13, 14.

230 THE PHENOMENON OF

6. The outer layers of the cell-membrane become,
sooner or later, cracked and peeled off, which takes place
either by rapid growth of the cell, not inclusively of the
outer membrane, as in the paraphyses of Diphyscium
(p. 177), or through more or less abundant secretions of
jelly alternating with the lamelle of the cell-membrane,
as already mentioned in the description of the phenomena
of “skinning” in Gleocapsa, Gleocystis, Pleurococcus
miniatus, Chroococcus decorticans (p. 182), Urococcus
(p. 178), and Schizochlamys (p. 181). The last-named
example,each new membrane being thrown off by a regular
dehiscence before the new one is formed, connects this
group of cases very clearly with the succeeding series.
The cell, as it were, new-born after every “ new skinning,”
is not regarded each time as a new cell, simply because
its character does not suffer any perceptible change.

2. Reconstruction without division in the transition
to fructification, or retrogressively from this to germi-
nation.—In both cases the vital process of the cell
acquires with the reconstruction a new direction of the
physiological activity, an altered destination; in the
former case, a transition from the vegetative growth to
the swarming condition of the gonidium, or the sleeping
condition of the spore; in the latter, on the contrary,
from the sleeping condition to the vegetative develop-
ment. If in such a transition no throwing off of a
membrane formed in an earlier condition takes place, as
is usual in the passage of swarming gonidia into germi-
nation,* and occasionally happens in the transition of

* What becomes of the very rapidly vanishing cilia in this transition I
have not been able to make out with certainty. According to Unger, they
are not thrown off in Vaucheria, but drawn in and smoothened down. In
Aphanochete repens I once saw, on a gonidium passing into the state of rest,
in place of the large cilia, two extremely short processes, which exhibited a
jerking movement, (alternately stretching forward and retracting,) for a
short time longer. The gonidia of Characium Sieboldii exhibit, after they
have already attached themselves by their ciliated extremities, a tremulous
motion lasting for almost a quarter of an hour, and evidently commencing
in the delicate stalk. These phenomena certainly speak rather for a retrac-
tion than for a casting off of the cilia.

REJUVENESCENCE IN NATURE. 931

cells formed by vegetative growth into spore-sleep (see
Chlamidomonas, p. 215), the cell is regarded as one and
the same before and after this transition, in spite of the
difference of the condition ; but if the earlier envelope is
broken open or cast off in the transition to the new state,
the cell in its altered condition is regarded as a new one.
‘The loosening of the new cell from the old cell-membrane
takes place either by a contraction of the whole internal
body (including the primordial utricle), as, for instance,
in the formation of spores of most of the @dogonia; or
it seems, vice versd, to be a swelling up of the contained
mass by occurrence of a secretion of cellulose, which
separates the primordial utricle from the cell-membrane,
as in the gonidia of @dogonium, Draparnaldia, &c. he
reason of the loosening of the contents of the special
mother-cell shaping themselves into a pollen-cell, from the
wall of the former, is explained by Hofmeister* by the
specific nature of the substance secreted all over the
outer surface of the primordial utricle, which substance,
not adhering to the thickening layers of the walls of the
special mother-cells, forms the primary (subsequently the
inner) membrane of the pollen-cell. ‘The following cases
may be cited, differing in the behaviour of the new cell
to the membranes of the mother-cell :

a. The new cell slips out of the membrane of the
parent-cell: as in the active gonidium of Vaucheria,
(edogonium, Bulbochete, Draparnaldia, Stigeoclonium,
Chetophora, Coleochete (see p. 183); the motionless
gonidium of Chantransia (p. 183); the spore of the
Fucoidez (p. 183).

6. The membrane of the parent-cell peels off the new
cell: as in germinating cell developing from the spore
of Mosses and Ferns, which throws off a mere incrusting
membrane; and of theZygnemacez, which breaks through
a multiple spore-coat (p. 180).

* Hofmeister, ‘ Ueber die Entwicklung des Pollens,’ (‘ Bot. Zeitung,’
1848, p. 431.)

232 THE PHENOMENON OF

ec. The new cell throws off the membrane of the
mother-cell by splitting of the latter into uncoiling spiral
filaments: as in the spore of Hguisetum (p. 180).

d. The new cell becomes free by the gradual solution
and resorption of the membrane of the mother-cell: as in
the pollen-cell of the Phanerogamia, the tetraspores of
the Florideze, and the spores, produced in fours, of the
Mosses, Liverworts, and Ferns, so far as they really
originate in special mother-cells. In the germs Archidium,
which. produces the largest but fewest spores of any of
the Mosses, it appears from Schimper’s description that
the spores are formed singly in the primary mother-cells,
and become free through resorption of the latter.*

B. RECONSTRUCTION WITH DIVISION OF THE CELL INTO
TWO DAUGHTER-CELLS.— Here we find repeated exactly the
same variations as we have seen in the reconstruction with-
out division; on the one side, retention of the previous
character (at least in essentials), and ordinarily combined
therewith intimate connection of the newly-formed cells
with the remains of the mother-cell; on the other side,
decided alteration of character, mostly connected with
emancipation from the membranes of the mother-cell.
The first case is again characteristic of the divisions con-
nected with the development of the vegetative tissues,
the latter of the transition to the formation of reproduc-
tive cells. Leaving out of view the division which occurs,
the analogy with the phenomena of reconstruction of the
cell without division is perfect. Thus, for example, the
membranes of the daughter-cells originating by division, if
these retain the character of the mother-cells, bear exactly
the same relation to the membrane of the mother-cell, to
which they immediately adhere in their origin, as the
thickening layers of the mother-cell where no division
occurs, so that if it be correct in the one case to speak

* ‘Recherches sur les Mousses,’ p. 77, t. 7, figs. 1—6. According to
Schimper, the capsule of Archidium contains 13—20 spores ith millim. in
diameter.

REJUVENESCENCE IN NATURE. 233

of the formation of Zwo cells insıde each mother-cell, it
will be equally correct in the other to call it a forma-
tion of one cell inside each mother-cell. In many cases,
indeed, it is altogether indifferent as regards the develop-
ment of the plant, whether such division takes place or
not. Compare, for example, H. von Mohl’s description
of some of the epidermal cells of Viscum album,* which
is equally fitted to illustrate the inessentiality of individual
cell-divisions, and the agreement of the behaviour of the
membranous layers of new cells produced by division,
with that of simultaneous thickening layers of undivided
cells. In like manner it is often indifferent in the forma-
tion of reproductive cells, whether the contents of the
mother-cell are transformed into a spore or gonidium
undivided, or divided into two cells. Thus in Coleochete
scutata, two gonidia are sometimes formed in one parent-
cell (by division of the contents) instead of one; in
Aphanochete repens (p. 184), on the contrary, it often
appeared to me that only one gonidium existed instead
of two (through omission of the dividing process); in
Stigeoclonium there occurs, in addition to the ordinary
formation of gonidia, a formation of microgonidia, in
which several gonidia are produced, instead of one, in a
mother-cell (see p. 139).

As to the great, even universal extent of the occur-
rence of division, and, in fact, halving of the cells, in the
development of the tissues of the vegetable organism, all
the most trustworthy of modern phytotomists, particu-
larly Mohl, Nageli, Unger, and Hofmeister, are agreed,
although they differ, in some respects, in their ways of
conceiving the dividing process; even Schleiden, who,

* “ Ueber die Cuticula von Viscum album,’ (Bot. Zeit., 1849, p. 593,
t. ix, p. 59.

+ Note Ihe following passages: “These researches have led me to the
conclusion, that all vegetative cell-formation is a parietal cell-formation”
(= cell-division). (Nageli, ‘Zeitschrift,’ 1847, p. 49, Transl. in Ray
Society's publications,. 1849, p. 121.)—‘‘As regards, in the first place,
vegetative cell-formation, I believe I am justified by comprehensive researches
in the Algw, Fungi, Floridee, Mosses and Chare, in the Vascular Crypto-

234 THE PHENOMENON OF

starting from the observation of cell-formation in the
embryo-sac of the Phanerogamia (the formation of endo-
sperm cells), formerly regarded free cell-formation as the
general law, (‘ Grundzüge,’ Ist ed., p. 195,) subsequently,
resting upon Nägeli’s researches, allowed cell-formation
by division a determinate although far too limited a
place, (‘ Grundzüge, 2d ed., p. 201; ‘Principles,’ pp. 34,
568.) In the vegetative development of the Alge I
have met with no other mode of cell-formation, so that I
must agree perfectly with Kützing, when he says, “ the
origin of the tissue of Alge by division is universal.’
(‘ Phyc. Gen.” p. 60.) But more than this, the propa-
gative cells of very many Algze are formed by division,
of which I shall hereafter mention.examples. In the
Characeze, the development of which I have been working
out for several years, all the cells, not only of the vege-
tative tissue, but those of which the antheridium and the
jointed filaments contained in it are composed, and even
the spore, are formed by cell-division.

The mode in which the process of division of cells
takes place has been represented in different ways. While
Unger* explains the division of the cell-contents by the
origin of a dissepiment (a partition), Nägeli,f compre-
hending more correctly the relations of dependence
between the formation of membrane and the contents,
states, vice versd, that the formation of the septum
proceeds from the contents, previously divided into two

amia, and in the Phanerogamia, in declaring ita general law, that here two
aughter-cells originate in a parent-cell, or in other words, that one cell
divides into two.” ies p. 66, Trans., p. 137.)—“ By formation of septa,
(cell-division,) therefore, the body of the plant grows; by formation of
septa the mass of the organic elements, the cells, &c., increases. Since
every plant is produced out of a simple cell, its growth ouly division and
partial separation (individualization) of the original ove, it is not to be
wondered at that, notwithstanding the multiplication of the One cell, a
connection of its parts, intensive as well as extensive, continues to exist.”
(Unger, ‘ Ueber Merismatische Zellbildung,’ 1844.) See also Hofmeister,
“Die Enstehung des Embryo der Phanerog.,’ p. 1, (note,) and p. 61.

* © Ueber Merismatische Zellbildung,’ 1844.

+ ‘Zeitschrift, 1844, p. 73 ct seq. (Ray Translation, 1845, p. 252);
1847, p. 51 et seq. (ibid., 1849, p. 123.)

REJUVENESCENCE IN NATURE. 235

halves; and Hofmeister,* in addition, directs attention
here more particularly to the primordial utricle, bounding
and cutting off the two parts from each other, even
before the origin of the cellulose dissepiment.

According to this representation, the septum is formed
by the two individualised portions of contents into which
the mother-cell divides, and which secrete cellulose upon
their whole surface after they become separately consti-
tuted, touching by their flat adjacent surfaces; whence of
course the cellulose layers formed on the surfaces of
contact become united, and thus form what appears a
simple septum, which, however, from the nature of its
origin, is composed of two plates, standing in unbroken
connection with the other parts of the new cellulose lining
which coats the sides of the cell turned towards the wall
of the mother-cell. Referring to the ad origine existing
contact of the daughter-cells with the whole internal
surface of the wall of the mother-cell, in formation of
cells by division of the whole contents, Nageli calls the
formation of cells by division “Parietal cell-formation.”
Under the hypothesis that the contents become com-
pletely divided before the formation of the septum, he
regards the latter as simultaneous through its whole
extent. In contradiction to this last assertion, Mohlf
describes in Confervee, particularly in Conferva (Clado-
phora) glomerata, a cell-formation taking place by gradual
constriction of the cell-contents, in which the formation of
the new layers of cell-membrane begins, before the com-
pletion of the division, over the whole surface of the
primordial utricle, and, since it penetrates the fold which
the primordial utricle forms at the place of constriction,
causes the formation of a septum penetrating gradually
from the circumference to the centre. In another place,

* «Die Entstehung des Embryo der Phanerogamen,’ p. 1; ‘Ueber der
Entwicklung des Pollens,’ (Bot. Zeit., 1848, p. 655.)

{ ‘Ueber die Vermehrung der Pflanzen-zellen durch Theilung,’ (Ver-
mischte Schriften, 1845, p. 362.)

+ “Einige Bemerkungen über der Bau der Vegctabilischcu Zelle,’ (Bot.

236 THE PHENOMENON OF

where Mohl describes the formation of the cells in young
points of stems and roots, and in the cambium layer of
Dicotyledons, he expresses a conjecture that the division
of the cells he observed in the Conferve is a totally
different process from the multiplication of cells in the
higher plants, since in cells dividing in this way no
nucleus can be found, while in the cell-formation of the
Phanerogamia these play an essential part. In the
multiplication of the cells of the Phanerogamia, moreover,
he never could observe a gradual constrietion of the pri-
mordial utricle. In seeking to advance this difficult
point nearer to its solution, I remark, first of all, that
the essential part of the problem is not so much the
question whether the cellulose septum is formed in
gradual progression towards the centre, or simultaneously
over its entire surface, but the question, whether the cell-
contents are divided by gradual annular constriction
(with in-folding of the primordial utricle), or through
simultaneous separation in the place of the entire sectional
plane, and the formation of two new coherent primordial
utricles. The succeeding formation of the septum might
be simultaneous in its entire extent, even in the first
case, if, namely, the formation of membrane on the whole
surface of the primordial utricle, did not take place until
the division was complete; and, on the contrary, the
formation of the septum might advance in annular incre-
ments, in the second case, if the secretion of membrane
on the newly-formed plate of the primordial utricle, did
not take place over the whole surface simultaneously, but
at the periphery earlier than in the centre. In the first
place, it is certain, notwithstanding Nägeli’s objections,
that the description given by Mohl of the cell-division
taking place in Cladophora, by gradual constriction of
the contents, corresponds to the truth. I have seen this
process so completely and clearly in the large species of

Zeit., 1844, pp. 289, 291,) (Transl. in “Taylor’s Scientific Memoirs,’ vol. iv,
p.96.—A. H.)

REJUVENESCENCE IN NATURE. 237

Spirogyra, that not the smallest doubt could remain of
the actual existence of the division completed by gradual
advance from the periphery to the centre.* The obser-
vation in Spirogyra is the more important, since a nucleus
exists in this genus, which assumes an equally important
part in the division to that it bears in the division of the
young cells of the Phanerogamia. Consequently this
takes away the principal reason brought forward by
Mohl in favour of the total difference of these two modes
of cell-formation, so that one might seek to explain the
distinction of the ordinary process of cell-formation,
characterised by the previous formation of new nuclei
and the sudden appearance of a line of fissure between
them, from the division by gradual constriction, by the
greater or less rapidity of an essentially identical process,
and to regard the first even as a gradually completed
division, only running through its course so rapidly that
the transitional stages are concealed from observation.
On the other side, it is true, an objection to such an
assumption may be found in the analogy of the process
of cell-division, such as occurs in young tissues, with free
cell-formation. In both the new cell-formation is intro-
duced in the same way by the formation of the nucleus,
and if, in free cell-formation, a mass of contents situated
around the shortly previously formed nucleus, becomes
bounded and cut off simultaneously over the whole peri-
phery (so far at least as observation reaches), analogy
would lead us to suppose that in cell-formation where
the entire contents of the cell part into two masses,
surrounding the newly-formed nuclei, each of these
masses of contents will bring as much of its periphery
as is not otherwise previously determined,—therefore its
surface of contact with its fellow,—simultaneously to
definition and completion in its whole extent. The
sharpness of the distinction in the idea of ordinary cell-
division, according as we try to bring it into agreement

* See the subsequent description.

238 THE PHENOMENON OF

with the constrictive division of the Conferva-cells, or with
free cell-formation, becomes softened to some extent, if
we reflect that the process which we have tcrmed con-
striction is by no means a mere mechanical process of-
folding-in, but rather a process of definition advancing in
the form of an annularly penetrating incision, that in this
case also the external division is preceded by the internal,
first expressed in the formation of two new nuclei, as
may be demonstrated at least in Spirogyra. Consequently
the question is, essentially, in which cases does the
cell-formation complete the development of the bounda-
ries on all sides and in all parts simultaneously, and in
which does it advance gradually and according to definite
laws. On this point, J am convinced, nature will be
found to exhibit a far greater multiformity than has
hitherto been suspected. As the cell in its subsequent
development displays sometimes an all-sided growth,
sometimes a one-sided, sometimes a two-sided, or a
growth regularly distributed in varying intensity in a
still more complicated way, there certainly exists a variety
of cases of regulated progress in the very first develop-
ment of the boundaries of the cell. Thus, in the lower
plants, there undoubtedly exists a division advancing
from one end of the cell to the other. In Chlamidococcus
pluvialis, in which the division of the cell in the later
active generations often begins even before the cessation
of the movement (see p. 208), I have very frequently
seen the division advance very gradually from the pos-
terior to the anterior, still ciliated extremity. A one-
sided advance of the division from the upper end of the
cell to the lower (which corresponds to the ciliated ex-
tremity of swarming gonidia) may be conjectured of
the Diatomacez with fan-shaped cells and dichotomous
peduncles (Gomphonema), as also of the Palmellacex
with delicate peduncles issuing from the internal cell-mass.
(Dietyospherium, Nag.) As regards the ordinary cell-
division, apparently taking place simultaneously over the
whole surface, it is a question whether or not the pri-

REJUVENESCENCE IN NATURE. 239

mordial utricle of the mother-cell (analogous to the
nucleus of it) is here totally dissolved and reconstructed.
For the former view, for a total solution and reformation
of the primordial utricle, it seems to me that no sufficient
reasons can be found, at all events in ordinary vegetative
cell-formation ; but if a total solution of the primordial
utricle does not take place, but merely an interruption of
its continuity in the periphery of the place of division,
the hypothesis of a completion of the primordial utricle
for each of the daughter-cells, through a formative move-
ment issuing and advancing from the parts already
formed, which is demonstrated by observation in Clado-
phora and Spirogyra, appears to me not improbable, even
for the seeming simultaneous division. The principal
distinction between these two cases depends evidently on
the age of the cell at which the division takes place.
There are cells which never become old, but in their
earliest age, by dividing, give up their existence again, or
rather continue it in a new generation, till age is finally
attained in a last generation, which never undergoes
division. This is the condition in the cells of the young
tissues of the higher plants, which often divide again
when scarcely formed, still small, and thin-walled, with
comparatively large nuclei, and abundant viscid con-.
tents. To such cells, which have not yet lost the
character of youth, belongs the apparently simultaneous
cell-division. Hofmeister* expressly remarks that this
kind of cell-formation takes place everywhere that the
volume of the mother-cell does not very considerably
exceed (at least about sixteen times) the circumference of
the nuclei of the new daughter-cells to be formed. On
the other side, there are cells (probably only in the lowest
stages of the Vegetable kingdom) which may be said
never to be young, since they display from their earliest
origin the characters of old cells; for instance, a nucleus
(perhaps sometimes altogether deficient) very small in

* «Die Entstehung des Embr. der Phanerog.,’ p. 1.

240 THE PHENOMENON OF

proportion to their frequently very considerable size,
a large internal cavity filled with watery fluid, parietal
distribution of the consistent portion of the contents,
fully-developed starch-grains, &c. To such old-born cells
belongs the gradually advancing multiplying division, as
has. been described by Mohl.

1. Reconstruction with division into two daughter-
cells, in the domain of vegetative cell-formation.

a. Halving through evidently gradual constriction ;
Old-cell-division.—The primordial utricles of the daughter-
cells are cut off by a process of formation advancing
gradually from the periphery to the centre; the formation
of the cell-membrane commences before the conclusion of
this cutting off, the septum is consequently formed in the
shape of an annular ridge (or properly a double-plate)
gradually increasing in breadth, finally closing-in in the
centre.

a. Without a nucleus? Were refers the cell-division
of Cladophore, in which at least no nucleus has yet been
found. It has been described in detail by H. von Mohl,*
in Cladophora glomerata, as above mentioned.

B. With a nucleus.—My observations on this point,
to be brought forward here, were made on Spirogyra
nitida and jugalis, which are probably both forms of one
and the same species, the former 4 — 4, the latter about
ı millin. in diameter. The position and character of
the nucleus of Spirogyra are well known; it appears
particularly sharply and distinctly when spirit is applied,
which however generally disturbs its originally central

* ¢Vermischte Schriften,’ p. 362, t. xii. With regard to the many-
layered membrane marked 5 in fig. 5, and c in fig. 14, T venture to remark
that the same is wrongly described at page 365, as a connected tubular
envelope of all the ccs as it were a colossal branched cell. Only the
gelatinous, slimy investment marked a, (fig. 5,) and d, (fig. 14,) forms such
an universal envelope; the many-layered membrane, on the contrary, forms
a very complicated system of encasement, since its innermost layer encloses
only two cells, its inmost one but three cells, and so on outward a pro-
gressively larger number of cells. In the further description, indeed,
especially at PP. 368-69, the assertion made at first is partially corrected
by Mohl himself.

REJUVENESCENCE IN NATURE. 241

position, and draws it to the side, through the contraction
and partial tearing up of the radiating mucilaginous
threads fixing it in the cavity of the cell. Before the applica-
tion of iodine it has a homogeneous aspect, and the line
of demarcation between its body and the surrounding
mucilaginous envelope running out into radiating fila-
ments, is difficult to see; on the application of spirit the
outline becomes clear, and the interior acquires a granular-
punctate aspect; the large nucleolus always existing also
appears punctated in the interior. The nucleus is some-
what lenticularly compressed in relation to the longi-
tudinal axis of the cell, its larger diameter amounting, in
Spirogyra nitida, on an average, to about 3d, that of the
nucleolus „th millim. The size of both increases some-
what during the ulterior development, and most con-
siderably just before the commencement of the division
of the cell, at which time its lenticularly-abbreviated
shape is also somewhat elongated. I have not been able
to make out clearly whether there is a division of the
nucleus here, or a solution of it followed by the formation
of two new nuclei, or how the nucleoli behave in this
doubling. When the cell is near to division, two new
nuclei present themselves in place of the original, con-
siderably smaller than it, and with proportionate nucleoli.
The two new nuclei touch at first, but I never saw them
lying flat upon one another, as if produced by division ;
they always had rounded surfaces. ‘The circumstance that
the two new nuclei are surrounded by a common, abundant
mucilaginous envelope, not existing previously, seems to
me to speak rather for a solution of the original nucleus,
than for a division of it. Simultaneously with the appear-
ance of the two new nuclei, we discover an extremely
delicate line upon the surface of the cell-contents, indi-
cating the division now beginning also at the periphery ;
this line is, however, so delicate at first, that when we
have the margin of the cell in focus, no trace whatever
of a grooving or constriction of the primordial utricle can

be detected, and the spiral chlorophyll bands, three of
16

242 THE PHENOMENON OF

which ordinarily exist in Sp. nitida, at this period retain
their course wholly uninterrupted. The two nuclei now
gradually separate from one another, the mass of mucilage
still enveloping and connecting them becoming at the
same time drawn out lengthways, and finally lost in
longitudinal mucilaginous cords running between them ;
an accumulation of granular mucilage often remains mid-
way between the two. Contemporaneously with the
separation of the new nuclei progresses the division com-
mencing at the periphery, and by no means as a coarse
constriction or folding, but in the form of an extremely
delicate incision, continually advancing deeper into the
cavity of the cell, with the sharp edges of the surfaces of
section reaching close up to the membrane of the mother-
cell, without being rounded off or separated by an
annular intercellular passage. In cases where the dis-
tance of the two nuclei equalled once or twice their
shorter diameter, the separation penetrating from the
periphery extended scarcely to a sixth part of the diameter
of the cell; where the nuclei were removed to a distance
of about four times their diameter, I found the division
advanced to 3ths, so that the part still open of the con-
nection between the two daughter-cells, was limited to
‘th the original diameter. The process of this gradually
incising partition of the daughter-cells can hardly be
otherwise explained, than through a gradually progress-
ing formation of two plates of the primordial utricle,
gradually shutting off the daughter-cells, these plates
starting from the line of limitation which has made its
appearance in the primordial utricle of the mother-cell,
and advancing towards the centre of the faces of contact
of the two daughter-cells. If we cause contraction of the
primordial utricle, and loosen it from the cell-membrane,
by the application of acids, in these cells also, which are
not yet completed, the walls of the incision retreat from
each other, to that the mass of contents enclosed by the
primordial utricle in such cells, appears constricted in
the middle by a widely opened groove, more or less deep

REJUVENESCENCE IN NATURE. 243

according to the degree of division. By this means also
we may satisfy ourselves that the secretion of cellulose
in the notch of the primordial utricle begins before the
termination of division, consequently that the septum is
originally an annular ridge, not reaching to the middle.
I could already distinguish its rudiment in cases in which
the notch occupied about ith of the diameter. Extremely
thin and delicate as the septum is in its earliest rudi-
ments, it separates completely from the walls of the
retreating notch of the primordial utricle, and appears
as a ridge attached at right angles on the cell-wall,
without an intercellular passage, diminishing to inappre-
ciable thickness at the bottom of the notch. That the
contents of the two daughter-cells are not merely appa-
rently (by adherence of the two portions to a septum
thinner in the middle), but really directly connected, in
these stages of transition, follows, not only from the
already described connection of the two nuclei by the
mucilaginous mass drawn out into a filament, but also
from the behaviour of the spiral chlorophyll bands. As
soon as the peripherical groove has attained a distinguish-
able depth, an interruption of the regular course of these
bands takes place ; they become pushed forcibly into the
interior of the cell at the point of transition, becoming, at
the same time, loosened from the primordial utricle for
some distance from the notch. The more they are bent
into the centre of the cell, the more they are attenuated
at the point of transition, till at length the connection is
dissolved. Icould trace their uninterrupted course from one
cell to the other distinctly, even in cases where the diameter
of the isthmus did not amount to more than :th of the
diameter of the cell. After the division is completed,
the position of the nucleus remains excentrical for some
time longer, nearest to the newly formed wall; but it
soon retreats to the middle of the cell, the mucilaginous
filaments radiating from it, which were at first directed
in greatest number and thickness to the newly formed
septum, finally run principally to the lateral walls of the

244 THE PHENOMENON OF

cell. The imperceptible increase of length during the
rapid course of this process, is a proof that the alteration
of position of the nucleus is a real change of place, and
not effected by a one-sided complementary growth of the
cell (like that in the Desmidiaces). Hence we ordinarily
find the nucleus again in its characteristic central position,
as in the older, larger cells, even in newly-formed cells
scarcely more than half the length of the mother-cells.
When the cells have attained the normal dimensions, by
doubling their length, the process of division is repeated,
till at length fructification commences. Excepting the
processes relating to the nucleus, no perceptible pheno-
mena of solution occur as preparatory to the division of
the cells; in particular, no change is detected in the
green bands or the starch-grains existing in them. I
have a little more to add in regard to the cell-membrane,
especially the relation of its different layers to the series of
generations of cells. In the larger Spiragyre a double
membrane may be clearly detected: an outer, which
envelopes all the cells of the filament in common, which
I will call the cuticle (Ueberhaut, cuticula) ; and an inner,
the true cell-membrane, which, when superficially ex-
amined, seems to belong to the individual cells, but, in
reality, represents a very complicated system of encase-
ments. Between the outer and inner coat, we may
sometimes distinguish by its darker colour a membranous
layer, which however is neither a simple nor a special
membrane, but belongs to the system of layers of the
internal membrane. The cuticle is very thin in Sp. nitida
and jugalis, at most 4; millim. thick, more transparent
than the proper cell-coat, from which it is distinguished
also by its behaviour with acids and solution of potash,
as it does not swell up. On the surface it exhibits very
numerous, irregularly scattered, sharply circumscribed,
circular bright points, scarcely ;2th millim. in diameter,
which in the sectional view of the cuticle appear as
streaks running crossways through it. These streaks
are still more distinctly seen m Sp. Zubrica, in which the

REJUVENESCENCE IN NATURE. 245

cuticle (4) is far thicker than the cell-membrane. When
tincture of iodine is applied, the said streaks acquire a
brown colour, while the mass of the cuticle remains
uncoloured, which, as well as the general aspect, makes
them look like little canals perforating perpendicularly
through the cuticle. We have no observations on the
mode of origin of this cuticle, but I should rather incline
to regard it as an incrustation-membrane, than as the
primary cell-membrane of the first cell of the filament.
‘he more complicated structure of the proper cell-mem-
brane only becomes evident after long action of solution
of potass, when the membrane, about „,th millim. thick,
swells up to almost three times the thickness, and dis-
plays clearly at least the principal constituents of which
it is composed. It consists, as examined from within
outward, of a series of layers, the inmost of which clothes
one cell only, the’ second two, the third four, the fourth
eight cells, &c. The first and second layers, from within,
are most clearly distinguishable, and one or other of them
is the thickest of all, according to the age of the cells;
the further outwards, the thinner and less distinguish-
able become the lamella, so that usually only four of
these can be distinguished, the outermost of which, how-
ever, (of course only in old filaments composed of
numerous cells,) we must regard as composed. of several.
These various layers are the membranes of so many
different cells encased one within another. The inmost
layer alone constitutes the special cell-membrane of the
individual actually vegetating-cell; at the time of the
full development of the cell, it is thickest of all. The
second layer is the membrane of the immediately pre-
ceding mother-cell, it therefore encloses two cells, and
beconies attenuated by the extension which it must
necessarily undergo during the period of growth of the
daughter-cells, so that it is only about half as thick as
the fully-developed membrane of the daughter-cell. The
third layer is the cell-membrane of the penultimate
mother-cell (the grandmother-cell) ; it encloses four cells,

246 THE PHENOMENON OF

and is about half as thick as the second, &c. By the
increased expansion and corresponding attenuation, which
the cell-membranes of the mother-cells lying further back
in the series of generations undergo, it is conceivable
that they must become constantly less clearly distinguish-
able as separate layers, and finally vanish entirely. Hach
such layer, or rather special cell-membrane, is itself again
composed of numerous extremely delicate lamelle, formed
successively during the life-time of the individual cell,
which, however, can only be detected in the inner thicker
layers, and there very indistinctly. The character of the
septa is most intimately connected with this system of
encasing of the cell-membranes. Between two sister-cells
the septum is composed of the mere continuation of the
innermost cell-membrane (that belonging to the individual
cell), clearly passing over into this, and increasing in
thickness in equal proportion during the growth of the
cell. The structure, as composed of two lamelle, may
be detected even in the very thi septa of young sister-
cells, in the swollen-up condition. No intercellular
passage exists at first in the periphery of the septum, but
it is gradually formed during the increase of thickness of
the septum, and is situated between the membrane of the
mother-cell and the two daughter-cell membranes forming
the septum. The septum between two pairs of daughter-
cells (between the first-cousin-cells), is formed of the
membranes of the daughter-cells and those of the mother-
cells, thus of four lamin; the intercellular passage
existing at its periphery is situated between membrane
of the grandmother-cell and membrane of the two adjacent
mother-cells. The septum between two double pairs of
of first-cousin-cells (between second-cousin-cells), is
formed of the membranes of the daughter-cells, mother-
cells, and grandmother-cells, thus of six layers; the
intercellular passage lies between the adjacent grand-
mother-cell membranes and the membrane of the great-
grandmother-cells, which, however, (together with all the
membranes lying outside it,) is so thin, that it appears as

REJUVENESCENCE IN NATURE. 247

if in contact with the cuticle. All this may be very
exactly traced out in the larger species of Spiroyyra ; and
I add, in conclusion, that all the subdivisions of the cell-
membrane (exclusive of the cuticle) swell up most
strongly in the vicinity of the intercellular passages.

A similar gradual progression of the cell-division will
doubtless be found in other Confervae not yet accurately
examined in this respect. Observation of the process of
division in Gdogonium and Ulothrix, which genera have
a lateral nucleus, would be very interesting. The rela-
tionship which exists between the Desmidiaceee and the
Zygnemacez, as also the occurrence of a central nucleus
observed in many of the genera of that family, leads to
the conjecture that their division corresponds to the pro-
cess in Spirogyra. In the Diatomacez the presence of a
nucleus is still doubtful; the age at which the division
takes place, however, leads us to expect a gradual pro-
gress of the division. Most genera of the two families
last named, present us, at the same time, with examples
of complete separation of the two cells formed by division,
the membrane of the parent-cell either gradually vanishing
or being peeled off. (See pp. 180, 181.)

6. Halving with (apparently ?) simultaneous definition
of the entire surface of division. Young-cell-division.—
This is the ordinary mode of formation of the cells in,
young developing organs of the Phanerogamia,* Vascu-
lar Cryptogamia, Mosses,f Characez, Floridez,{ and
Fucoidez.§ The formation of the special mother-cells of
the pollen of.the Phanerogamia,|| and of the spores of
the Cryptogamia, when this takes place through repeated
halving, also belongs here; in like manner the formation

* See, for instance, the course of development of the ovule of Orckis, in
Hofmeister, ‘Die Enstehung des Embryo der Phanerogamia,’ pp. 1—3, t. i,

rt Nageli, ‘ Zeitschrift,’ 1845, p. 138, t. ii, iii.

+ Ibid., 1845, p.119, t.i, (‘Growth of Delesseria Hypoglossum’ ) and 1847,
p. 207, t. vi, vii (Polysiphonia.)

§ Ibid., 1844, p. 73 et seq. ;

|| Nägeli, ‘Entwicklungsgeschichte des Pollens,” 1842; Hofmeister, Ueber
die Entwicklung des Pollens,’ (‘ Bot. Zeitung,’ 1848, pp. 425, 649.)

248 THE PHENOMENON OF

of the cells of the embryo of the Phanerogamia, and in
many cases even the formation of the endosperm-cells.*
Numerous researches on this kind of cell-formation agree
essentially in the following points: the nucleus of the
mother-cell is more or less completely dissolved ; in its
place are produced two new nuclei, either near together,
or at a distance. Between these suddenly appears a line
of division (really a plane of division) which indicates a
parting of the cell-contents into two portions, each of
which encloses one of the nuclei. The two portions of
contents are originally bounded only by their primordial
utricles, which immediately secrete a new cell-membrane
over the whole of their surface, and thus form a septum
between them at the surface of contact. Many observa-
tions testify that the two daughter-cells are completely
separated, by the shutting off of their primordial utricles,
before the origin of the septum. Thus Mohlf frequently
observed two primordial utricles in oze cell, in cambium,
as well as in the tips of stems and young leaves of various
plants; Hofmeister} represents such a case in the embryo
of Leucojum aestivum, and also, in the description of the
formation of the special mother-cells of the pollen of
Passiflora, and Pinus,§ endeavours to show the formation
of the septum to be subsequent to the division of the pri-
mordialutricle. With regard to the behaviour of the nucleus,
it must be remarked, that according to the observations of
Mohl and Nägeli, the formation of the two new nuclei takes
place in many cases through division of the nucleus of
the mother-cell|| (without solution of this). It seems to

* Hofmeister, ‘Die Enstehung des Embryo der Phanerogamen,’ 1849,
e.g. p. 35, t. xi. (Monotroße) ; p. 40, t. iii. (Bartonia.)

} ‘Bot. Zeitung,’ 1844, p. 290, (Trans. in “Se. Memoirs,’ vol. iv,
p. 96.—A. H.)

{ ‘Die Enstchung des Embryo,’ t. vi, f. 20.

‘ Ueber Pollen,’ ‘ Bot. Zeitung.,’ 1848, pp. 654, 671.

|| Vide Nägeli, “Zeitschrift,” 1844, p. 75. (Trans. in Ray Society’s
publications, 1845, p. 254,) where is described, of Sphacelaria, a division of
the central nucleus of the mother-cell preceding the division of the cell,
while in Zoxaria Pavonia, and Cystoseira, the parent nucleus is said to

REJUVENESCENCE IN NATURE. 249

me very doubtful whether two different conditions of this
case really occur, since a rapid reconstruction of the
nuclei of the daughter-cells out of the still accumulated
mass of the nucleus of the mother-cell, in a state of
solution at its periphery, may readily be looked upon as
a division of the latter.

How far either the partition of the primordial utricle,
or the formation of the dissepiment between them, is
really, or only apparently, simultaneous over the whole
face, can scarcely be decided in the present stage of
observation. Very few observations speak in favour of
the latter assumption. In one case, certainly referring
here, namely, to the ‘‘ young-cell-division,” in the forma-
tion of the stomate-cells (see the preceding note), Mohl
asserts that he observed the formation of a septum
beginning with the production of an annular ridge. I
should consider as an indication that the division of the
primordial utricle also begins at the periphery, the
formation of the at first simple zone of granules, subse-
quently doubled by a clear line of division, at the equator
of mother-cells of the pollen of Pinus* preparing for
division, and already provided with two nuclei,—a phe-
nomenon which seems to indicate a conflict of the two
newly-formed centres, expressing itself first of all at the
periphery of the plane of division, when they are defining
their boundaries. I shall hereafter mention a structure

vanish, and be replaced by two new ones. Nigel further describes the
division of the nucleus in the cells of the hairs of the stamens of Tradescantia
(1. ¢., p. 67; Ibid., 1847, p. 102—Translation in Ray, vols., 1845, p. 246,
1849, p. 168,) while according to Hofmeister, (‘Enst. des Embryo,’ p. 8,
t. xiv, figs. 20, 28) the membrane of the parent nucleus is absorbed, so that
only the mucilaginous and no longer sharply defined body of its contents, is
divided into two globular balls, which become the new nuclei. Accordin
to Mohl, (‘Vermischte Schriften,’ p. 252,) the nucleus of the mother-cel
becomes divided, in the formation of stomates, to form the nuclei for the
two boundary cells of the stomatal opening. According to Nageli, (‘Linnza,
1842, p. 237,) on the other hand, the formation of the two new nuclei is
preceded by a disappearance of the nucleus of the mother-cell.

* Hofmeister, ‘ Bot. Zeit.,’ 1848, p. 671, t. vi, f. 22, 24. In Passiflora,
on the contrary, the zone of granules is replaced by a granular plate occupy-
ing the whole surface of division. See t. vi, f. 8, 9.

250 THE PHENOMENON OF

analogous to this zone of granules in the description of
the formation of the gonidia of Hydrodictyon.

2. Reconstruction, with division into two daughter-
cells, in the domain of fructification.

a. The newly-formed cells are neither connected
together, nor with the membrane of the mother-cell.
The cells produced by division either divide anew (as
a transitory generation), without having acquired a
cell-membrane, or, if no fresh division occurs, they
are set free, naked and furnished with cilia, by tear-
ing of the mother-cell. Here belong the gonidia of
many Algz, of which mention has been already fre-
quently made. Either two gonidia are formed in one
mother-cell (by simple division of the contents), as in
Ulothrie Braunii (see pp. 177, 183), Aphanochete
repens (p. 184); or four, eight, sixteen, or thirty-two
gonidia, according as the division is repeated once or
more times, as in Ulva, Enteromorpha, Ulothrie zonata
(p. 184), Characium (p. 185), Chlamidococcus (pp. 184,
206, &e.), &e.

6. The newly-formed cells, free (active) at their birth,
become united into a regularly arranged colony after
birth. This occurs in Pediastrum (p. 184).

c. The newly-formed cells become combined into
families before birth, either united by formation of firm
membranes, as in Scenedesmus (Nägeli, ‘Hinz. Algen,’
t. v. a), or held together by a development of gelatinous
matter, as is the case in the Volvocinee.

B*. RECONSTRUCTION, WITH DIVISION, INTO TWO CELLS,
ONE OF WHICH REMAINS AS THE MOTHER-CELL, THE OTHER
BEING SHUT OFF (ABGEGLIEDERT) AS A DAUGHTER-CELL.—
In the cases comprehended under B, the two cells formed
by the division of the mother-cell are either alike in every
particular, or, if they differ, take an equal share in
the process of Rejuvenescence through which they are
formed, appear both equally active agents in the re-
construction, and therefore are regarded as equal
daughter-cells of one mother-cell (destroyed by the

REJUVENESCENCE IN NATURE. 251

division). But there are other cases in which the re-
juvenising activity appears solely, or at least principally,
in a definite part of the mother-cell, which becomes
finally cut off, as a newly-formed daughter-cell, by
division of the contents and formation of membrane,
from the other relatively inactive portion, retaining un-
changed the properties of the mother-cell.

The distinction of a shutting off of this kind from
ordinary division, is especially evident whenever the
behaviour of the nucleus can be observed, as is the case
in certain examples described by Hofmeister, which I
shall mention hereafter. In such cases, namely, instead
of the formation of two new nuclei, a single new nucleus
presents itself in some portion of the mother-cell (often a
prolongation or bag-like protrusion), upon which the
part of the mother-cell containing the nucleus separates
as a distinct cell. ‘The original nucleus remains during
this process in unaltered existence, or, if it has vanished
before the formation of the daughter-cell, no new nucleus
is formed in the part remaining as mother-cell during
the cutting-off of the new cell. Nägeli* and Hofmeistert
have applied to this modification of cell-division the term
“tying-off” (Abschnürung), a name, however, only
properly applicable to those cases where the daughter-cell
becomes externally detached from the mother-cell. Mul-
tiplication of cells by the formation of shut-off dranch
sprouts likewise belongs here.

1. The shutting-off (Aögliederung) of a daughter-cell,
in the domain of vegetative cell_formation.

a. The apex of the cell is shut-off as separate cell.

a. Without nucleus? Here refers the formation of
the mother-cell of the active gonidium, as also of the
motionless spore of Vaucheria, under the hypothesis,
that in both these cells a proper membrane is formed
(sharing the formation of the septum), before their

* «Zeitschrift, 1847, p. 60, (Ray Trausl., 1849, p. 131,) ‘ Einzell. Algen,’
18.
: + ‘Enst. des Embryo der Phanerog.,’ p. 61.

252 THE PHENOMENON OF

contents are metamorphosed into a fructification-cell ;
therefore that they have a vegetative existence, short
though it be, previously to the fructification. In the later
behaviour, the difference presents itself, that the gonidium
leaves its mother-cell by slipping out, while the spore
appears to tear away the membrane of the mother-cell
with it. The formation of the fruit-club of Saprolegnia
also belongs here. The process of shutting off the apex
may be repeated many times, in a retrogressive order,
in the same cell, as occurs not unfrequently in Saprolegnia,
where a second, and often a third piece of the cell is
developed, underneath the first fruit-club, into a gonidium-
case or spore-case (both are met with). Or the shut-
ting off is repeated in an apex reproduced by a growing
through of the emptied fruit-sac, as likewise occurs in
Saprolegnia (particularly S. ferax, S. prolifera) and in
Vaucheria clavata.*

ß. With a nucleus. A remarkable example of this
is furnished by the origin of the sacculate appendage of
the embryo-sac of Bartoniu, described by Hofmeister.t

The upper end of the embryo-sac (the mother-cell of
the germinal vesicles and endosperm-cells), after three
free germinal vesicles have been formed in it, produces a
prolongation penetrating into the canal of the micropyle,
which, after the previous formation of a nucleus, becomes
shut off from the embryo-sac as a separate cell. In general
the primary nucleus of the embryo-sac is not dissolved
during this process. The first division of the germ-cell (the
germinal vesicle) of the same plant} affords another
example. The originally roundish, nucleated germinal
vesicle becomes elongated in the form of a tubular cell,
the nucleus at the same time vanishing. In the front
part of the cell, turned away from the micropyle, a some-
what flattened nucleus is now formed, and in consequence
of this a separation of this anterior extremity as a dis-

* Vide Unger, |. c., fig. 13.
+ ‘Enstehung des Embr. der Phanerog.,’ p. 39, t. ii, f. 34£—40.
+ Hofmeister, 1. c., p. 40, t. mi, f. 4—11.

REJUVENESCENCE IN NATURE. 253

tinet cell, while no new nucleus is formed in the longer,
posterior part of the cell. According to Hofmeister,*
the second cell of the proembryo (the cellular filament
first developed from the germinal vesicle, the suspensor)
is formed in a manner essentially the same, in Monotropa,t
Gagea,} Fritillaria, Martynia, and Linum.

. 6. A lateral growth from the cell (a cell-branch)
becomes shut-off as a separate cell. This process also
may be repeated in the same mother-cell when several
branches arise from it one after another, as occurs in
Cladophora glomerata. 'The branches arise sometimes
from the upper margin, sometimes from the lower, and
sometimes from the middle of the cell ; sometimes from
the upper and lower border at the same time, as men-
tioned already of Chetophora and Coleochete pulvinata
(p. 150). According as the ramification commences in
the earliest youth of the cell, or at a later epoch, in
somewhat advanced development of the cells, the shutting-
off of the branch may exhibit distinctions of mode and
kind, analogous to those we have characterised as young
cell-division and old cell-division.

a. Without a nucleus? Ramification of Cladophora,
Chantransia, Chroolepus, Draparnaldia, Chetophora, &c.
In many of these genera the nuclei have certainly been
merely overlooked.

ß. With a nucleus. Were belong the Fucoidez and
Floridee, in the ramification of which, according to
Nägeli’s conjecture,§ the original nucleus remains in the
cavity of the mother-cell, while a new nucleus is formed
in the protrusion becoming the branch-cell.

With these “ baggings-out” of the cells, giving origin
to the branches of the lower plants, may be compared,
to a certain extent, the ZAylis, those remarkable cell-like
structures which fill up the wide vessels of wood in old

* Hofmeister, 1. c., p. 6.

lbid., p. 36, t. xl, f. 9—14.

| Tbid., p 22, t. ix, £. 9—14.

\ ‘Zeitschr.,’ 1847, pp. 71, 72, (Modes of Cell-formation, 8 a and B.)
(Ray Transl., 1849, pp. 141, 142.)

254 THE PHENOMENON OF

age, and, according to the researches of an anonymous*
author, sprout forth as little utricular protrusions from
the cells of the surrounding tissue, and penetrate through
the thin-walled canals of the dots into the vessels. In
these thylls, which appear quite as true, partial, and local
Rejuvenescences of the cells, nuclei are formed at a time
when those of the mother-cell have long since vanished,
never becoming renovated.

2. Shutting-off of a daughter-cell in the domain of
Jructification. The shut-off and detached daughter-cell
becomes a spore, while the mother-cell remains vegetative.
This case doubtless occurs in the spore-formation of many
Fungi, particularly the true Hymenomycetes,f many
Gasteromycetes,{ and most Hyphomycetes.$

The multiplication of the cells in the Algal genus
Exococcus (Nägeli, ‘Algensyst,’ 169) and the fermentation
Fungi,|| also takes place by the shutting off, and fre-
quently complete tying-off (Abschnürung) of either
terminal or laterally budding daughter-cells. But as all
the cells are of like character here, these cases would be
more properly referred to the domain of vegetative cell-
formation.

c. RECONSTRUCTION, WITH DIVISION INTO FOUR
DAUGHTER-CELLS.—F rom the pregnant discoveries of Ad.
Brongniart and H. v. Mohl,** on the formation of the

* © Untersuch. üb. die Zellenartig. Ausfullung. der Gefasse,’ (‘ Bot. Zeit.,’
1845, pp. 225, 241, t. ii.)

T See Phoebus, ‘Ub. der Keimkornerapparat. der Agaricen,’ &e., ‘Nov.
Act. Nat. Cur.,’ xix, 11, (1842,) p. 171, t. 56, 57. Corda, ‘Ic. Fung., iti,
t. 7—9; iv, t. 10, fies. 134—139; v, t. 10.

£ See Tulasne, ‘De la Fructification des Scleroderma comparée & celle des
Lycoperdon et Bovista, ‘Ann. des Sc. nat., 17, (1842,) p. 5, t. 1, 2, ‘Sur
les Genres Polysaccum et Geaster'? ibid. 18, (1842,) p. 129, t. 6.

§ See Schleiden, ‘Grundz.,’ ii, pp. 38, 39, figs. 106, 107, (« Principles,’
pp. 153, 154, figs. 122, 123; Corda, ‘Ic. Fung.,’ ii. t. 10, fig. 68, (Verti-
cillium ;) ili, t. 1, fig. 28, (Botrytis) ; iv, t. 10, fig. 132 (Isaria).

I Bee Saccharomyces Cerevisia, in Meyen, ‘ Pflanzen-physiol.,’ i, p. 455,
t. x, f. 22

1: a Génération et le Développement de l’Embryon,’ ‘ Ann. des Sc.
nat., 1827.

** «eb. der Bau und die Form der Pollenkörner,’ (1834); ‘Ub. die

Entwicklung und den Bau der Sporen der Kryptogamische Gewächse,’
(‘ Flora,’ 1833,) ‘ Vermischte Schriften,’ p. 67.

REJUVENESCENCE IN NATURE. 255

pollen-grains of the Phanerogamia and the spores of the
Cryptogamia, the formation of four daughter-cells in each
mother-cell appeared to be a case of very frequent occur-
rence, widely diffused in the condition of transition to
fructification. From more recent researches, however, on
the processes which precede the formation of both the
pollen-grains and the groups of four spores,* in the mother-
cell, the nature of the formation is not so simple as it at
first appeared. The pollen-grains and spores are not
formed immediately in fours in the mother-cell, but singly
in special mother-cells, so that the origin of the number
four is to be examined in the latter. According to
Nageli’s researches, this takes place in two ways. The
mother-cell either divides at first into two daughter-cells
(primary special mother-cells), which then each divide again
into two (secondary special mother-cells) ; or the mother-
cell divides immediately into four daughter-cells, in which
case, consequently, only one generation of special mother-
cells (merely primary) is formed. Only the second case
belongs to the present section of our subject. From
researches hitherto made, it seems to follow that in the
first mode of origin the group of four (secondary) special
mother-cells are usually placed in oze plane ; in the latter
the four (primary) special mother-cells in two planes,
or in the order of the angles of a tetrahedron. If this
relation of the arrangement to the mode of origin were
constant, it would be an easy means of ascertaming the
direct or indirect formation of the group of four special
mother-cells, ata later epoch, from the arrangement, nay
even in many cases from the form (in a great measure
dependant on the original position) of the spores or
pollen-grains.{ But this relation is not constant. Ac-

* Here belong the formation of the species of the Ferns, Mosses, and
Hepatice ; both kinds of spore-formation in the Lycopodiacex, Isoetacex,
and Rhizocarpes ; and one kind of spore-formation in the Floridez.

+ ‘Zur Entwick. des Pollens der Phanerog.,’ 1842.

+ Quadratic (situated in one plane) position and elongated form of the
pollen-grains occurs principally in the Monocotyledons ; tetrahedral position

and roundish form almost universally in the Dicotyledons, (Mohl, 1. c., p. 34.)
Both cases are likewise repeated in the spores of Ferns, the former (longish

256 THE PHENOMENON OF

cording to Nägeli’s* observations (on the formation of
the pollen of Zilium), the tetrahedral arrangement of the
four special mother-cells occurs also when they are
formed in the second generation, when the two primary
special mother-cells first produced are divided, not in the
same, but in a different direction, producing a decussating
‘arrangement of the two pairs.t On the other hand, it
follows from Hofmeister’s description of the formation of
the pollen in Pirus,} that four special mother-cells lying
in one plane may be produced by simultaneous formation.
But what seems to us of still more importance here, is
the observation, that not merely the various modes of
arrangement, but even the cases, which we should suppose
very essentially different in their mode of formation, of
primary and secondary, direct and indirect formation of
special mother-cells, are not exclusive of each other in
their natural occurrence, since they sometimes occur in
substitutive alternation in one and the same plant.
Nägeli has named A/thea rosea as a plant in which the
special mother-cells are formed in one generation (four
at a time), and also sometimes in two successive gene-

shape, with a longitudinal keel,) e. g., in Polypodium vulgare, Ceterach
oficinarum, Asplenium Ruta muraria, Aspidium Filix ferina, &e.; the latter
(producing the form of a triangular pyramid rounded at the base,) in Pterts
longifolia, serrulata, Allosorus crispus, Notochlena marante, Osmunda regalis,
&c. (H. von Mohl,’‘ Verm. Schrift.,’ 69,70.) In the Mosses and Hepatica
the tetrahedral arrangement seems to be predominant, likewise in the Lyco-
podiacex and Rhizocarpex, in the latter of which this is indicated by three
short lines united in the form of a tripod, both on the small and imperfectly
developed large spores, (Mettenius, ‘Beiträge zur Kenntniss der Rhizo-
carpeen,’ t. i, of Salvinia.) In the Floridee there occurs a third mode of
arrangement, in addition to the quadratic and tetrahedral, namely, the linear,
(Kiitz., ‘Phyc. gen.,’ p. 100,) “spermatidia quadrijuga.” See, for instance,
t. 60, iv, Hypnophycus musciformis, and t. 62, iii, Calliblepharis ciliata.

* Nageli, ‘ Entwick. des Pollens,’ p. 18, t. ii, £. 19, 20, 21.

{ The shape of the four secondary special mother-cells, (and consequently
of the pollen-grains or spores,) is in this case, however, different from that
in the tetrahedral arrangement through direct formation; in the former case
the four portions, (as in the quadratic arrangement,) have the form of quarters
of a sphere, in the latter the form of a three-sided pyramid with a rounded
base. If the two modes of arrangement require to be distinguished, the
former may be called the decussate, the latter the pyramidal or tetrahedral
in a restricted sense. (See also Nägeli, ‘Neueren Algensysteme,’ p. 190.)

+ ‘Bot. Zeitung.,’ 1848, 671.

REJUVENESCENCE IN NATURE. 257

rations (two and two). Hofmeister mentions the opposite
case as occurring in Tradescantia, in which the special
parent-cells are usually formed two and two (in one plane
or decussating), sometimes, however, all four simul-
taneously (in tetrahedral position).* This remarkable
circumstance indicates an intimate connection of the two
cases, to which we are still more definitely attracted by
certain observations on the behaviour of the nucleus
before the direct quartering. In the first place, we must
here recall the remarkable course of development of the
spores of Anthoceros, described by H. von Mohl,f and
also by Nageli.{ At the sides of the central nucleus of
the mother-cell, here, as an exception, not vanishing, two
new nuclei are formed (called by Mohl, from their
granular contents, “ granule-cells”), which after some
time divide, thus producing four nuclei, which, gradually
retreating from each other, assume a tetrahedral arrange-
ment. Around these four nuclei the special mother-cells
are simultaneously formed, by division of the entire
contents of the general mother-cell. Still more expressive
are the observations made by Hofmeister on the forma-
tion of the pollen of Pinus.$ The large nucleus becomes
dissolved; two secondary nuclei are formed; between
these two the granules of the cell-sap accumulate as an
annular zone at the equator of the cell; the zone of
granules soon splits into two parallel zones, indicating
the separation of the primordial utricle into two halves.
Up to this point all the mother-cells behave alike, but
the subsequent development takes place in two different
ways. Hither the indicated division into two primary
special mother-cells is carried out, and two secondary
special mother-cells are formed again in each of them; or
the commencing halving of the primordial utricle is inter-

* Bot. Zeit.,’ 1848, p. 430, t. iv, f. 22—25.
+ ‘Ueber die Entwick. der Sporen von Anthoceros levis,’ (Linnea, 1839 ;)
*Verm. Schrift.,’ p. 84, t. iv.
+ ‘Zeitschrift,’ 1844, pp. 49—54, t. i, f. 31—40. (Ray Transl., 1845,
pp. 229—233, t. vi, fig. 31—40.)
§ ‘Bot. Zeit.,’ 1848, p. 671.
17

258 THE PHENOMENON OF

rupted, the two secondary nuclei vanish, and in place of
each one of them appear two tertiary, making four nuclei
in a cell, which either lie in one plane, or are arranged
like the angles of a tetrahedron, and the formation of the
four special mother-cells now takes place directly around
these. Supported by these observations, we might cer-
tainly conjecture, that all those processes of cell-formation
which, according to the external definition of the cells,
appear as direct quarterings, are essentially the same as
the double halving, only distinguished from the latter by
skipping over one step of the course of the formative
process, advancing, namely, from the first halving,
already indicated by the formation of two secondary
nuclei in the interior of the cell, without completing this,
to the succeeding halving.

In the multiplication of the Unicellular Algze, especially
in the family of the Palmellaceze and those nearest allied
to them, we meet with undoubted cases of true quartering
(in the sense just explained), together with apparent
quartering. The latter results from the first halving,
which produces merely a transitory generation of cells,
being followed immediately by a second.* Here also
the arrangement of the cells in one plane not unfrequently
alternates with the decussate, as I have observed, for
example, in Chlamidococcus pluvialis. Nägeli gives
genuine (and tetrahedral) quartering as the character of the
genus Tetrachococeus, the independence of which he, how-
ever, doubts himself, placing it as a sub-genus under
Pleurocococcus, and leaving it undecided whether the form.
of Alga thus characterised does not belong to Pl. vulgaris.t
I have observed intermingled, in Protococcus viridis, mere
halving, apparent (decussating) and true (tetrahedral)
quartering ; the latter two distinguishable by the form of
the cells, from which alone I could draw inferences as to
the mode of formation in this case.

* Lhave already directed attention to the circumstance, above,(p.160, note.)
t Nageli, ‘Zeitschrift,’ 1847, p. 70, (Ray Transl, 1849, p. 140,) ‘ Neuer.
Algensyst.,’ p. 127. j

REJUVENESCENCE IN NATURE. 259

D. RECONSTRUCTION WITH DIVISION OF THE CONTENTS
OF THE MOTHER-CELL INTO AN INDEFINITE NUMBER OF
DAUGHTER-CELLS.—The cases to be mentioned here all
belong to the fructification of the Algze, Lichens, and
Fungi; they have hitherto been included, especially by
Nägeli, not under cases of cell-formation by division,
but of free cell-formation, from which, however, they are
essentially distinct. While, in free cell-formation, the
mother-cell, notwithstanding the formation of daughter-
cells taking place in it, preserves its own vitality, that is,
continues to exist as a living cell, consequently possesses,
in addition to the daughter-cells, vitally active contents
bounded by the persistent primordial utricle, and often
still furnished with a well-preserved nucleus ;—in the
cases to be examined here, as in all formation of daughter-
cells by division, the mother-cell dies at the very first
formation of daughter-cells: which is especially indicated
by the constant dissolution of the primordial utricle of
the mother-cell. The entire contents of the mother-cell,
at most with the exception of a watery fluid containing
but few organic constituents, become applied to the
formation of the daughter-cells, and not by actually
existing daughter-cells gradually consuming it, but in
such a way that the whole contents (so far as available
for reconstruction) are divided among the daughter-cells
at the earliest definition of the boundaries of the latter.
Hence the cells do not originate with free bounding
surfaces, but in original contact both with each other
and with the wall of the mother-cell; but they may
separate subsequently, or, if the watery contents of the
mother-cell are excluded from the new structure, even at
the first completion of their formation.

1. The daughter-cells are formed by the division of
contents filling the entire cavity of the mother-cell.—
This case presupposes that the whole contents are
mucilaginous, and capable of sharing in the process of
reconstruction.

a. The daughter-cells lie in one row in the mother-

260 THE PHENOMENON OF

cell_—The cylindrical cell of Sciadium (see p. 187) pos-
sesses uniformly distributed green contents, which are
interrupted in perfectly developed cells by light cross
streaks, and are divided into a row of 58. about equal
masses, which become gonidia. I could not detect
nuclei in the individual segments of the contents passing
into the formation of gonidia. Probably the conditions
are similar in Ophiocytium (Nag. ‘ Binz. Alg. iv, a). It
seems to me probable that the formation of spores in the
cylindrical or fusiform mother-cells (asc) of the Lichens,
Pyrenomycetes, and Discowycetes, belongs to this kind of
cell-formation. The greater concentration of the con-
tents which accompanies the formation of resting spores,
causes the exclusion of the watery portion of the contents
of the mother-cell, and hence a detached position of the
spores presenting itself in the earliest period of their
isolation. The development of the spores of Peziza
Acetabulum, as described by Corda,* leaves scarcely a
doubt in this respect. In the equably diffused, opake,
and granular fluid contents of the mother-tube is formed
a row of globular structures, ‘standing at regular dis-
tances, called by Corda drops of oil, which, from their
relation to the subsequent formation of the spores, appear
to be nuclei. Around these nuclei a lighter atmosphere
is formed, the darker granular mass accumulating in the
form of zones between them: which reminds us of the
analogous phenomena in Hydrodictyon, and in the forma-
tion of the pollen of Pinus and Passiflora. Soon after
this, the individual globular nuclei appear surrounded by
masses of contents and membranes, consequently as the
central structures of so many longish spores, which are
separated by a light, watery fluid, containing but very
few granules.

b. The daughter-cells fill up the mother-cell irregu-
larly.—I think we may reckon here the formation of the
gonidia of Chlorococcus (according to Nägeli),} also of

* «Teones Fungorum,’ iii, p. 38, t. vi, figs. 95, 96.
i Zeitschrift,’ 1847, p. 23, (Ray Transl., 1849, p. 96,) ‘Binz, Alg.,’
p. 17.

REJUVENESCENCE IN NATURE. 261

Chytridium (p. 185), in which genus the nuclei scattered
through the whole contents of the mother-cell, are clearly
distinguishable before the formation of the boundaries of
the gonidia. Perhaps the formation of the spores of
many Fungi, in particular the genus Zrysiphe,* belongs
here.

2. The daughter-cells are formed by the division of a
mucilaginous layer coating the inside of the wall of the
mother-cell.—Since this by no means very rare mode of
cell-formation—to which the term “ parietal cell-forma-
tion would seem apt, were it not already used in another
sense—has never yet been acurately described, I shall
give a somewhat detailed account of it, as I ‘observed
step by step in the formation of the gonidia of Hydro-
dictyon. J have already spoken of the strange mode of
reproduction of the Water-net (pp. 137, 222); and
the characters of the cell-contents (pp. 171, 197) and
the cell-membrane (p. 190), before the commencement
of reproduction, have also been explained; so that,
taking up the subject at that point, I may commence
immediately with the description of the phenomena
through which the beginning of the formation of gonidia
is announced, The first stage, introducing the formation
of the gonidia, comprises the period of solution and dis-
appearance of the starch-grains. The mucilaginous layer
(2. e. the more consistent, formative contents resting
against the cell-membrane, the subordinate divisions of
which have been described above, and which retain their
parietal position up to the completion of the formation of
the gonidia) changes its aspect in a remarkable manner at
this period. The fresh transparent green becomes more
opake, and the entire mucilaginous layer acquires, even
before the solution of the starch-granules is completed, a
peculiar, regular appearance, closely beset with lighter
spots, which appearance, however, is only distinctly per-
ceptible when the focus is adjusted to the bottom of the

* See Corda, ‘Icon. Fung.,’ ii, t- xiii, f. 100.

262 THE PHENOMENON OF

niucilaginous layer. hese spots are not the starch-grains
undergoing solution, as might be conjectured, for their
number is much larger than that of the latter, the not
quite lost nuclei of which may still be remarked here
and there, and not in, but between the spots. The little
green granules of the contents, which, for the sake of
brevity, I shall call chlorophyll-granules,* do not disap-
pear with the starch-grains, but separate from each other
at the period of the formation of the spots, and become
accumulated as darker boundary lines between the
brighter spots. By adjusting the focus up and down we
may ascertain that scattered chlorophyll-granules occur
also above and beneath the light spots, while the spots
themselves are roundish spaces, free from granules,
existing in the thickness of the mucilaginous layer.
Simultaneously with these processes the green colour of
the mucilaginous layer passes more into a brownish,
a change of colour which shows itself still more clearly
in the next stage, especially in those cells in which
microgonidia (swarmers) are to be formed. Still more
striking alterations present themselves in the second stage
of the formation of gonidia, in which the mucilaginous
layer exhibits a picture diametrically opposed to that just
described. The granules retreating towards the bright
spaces, the earlier dark net-work of the granules is
replaced by a net-work of lighter boundary lines; the
former bright spots, on the contrary, become darker areola
through the collection of granules into groups. When the
new distribution of the contents is complete, the light inter-
mediate streaks appear as everywhere pretty equally broad,
light-yellowish (not green) lines, sharply defined upon the
dark field ; the latter displays little polygonal (mostly hex-
agonal, rarely pentagonal or heptagonal) green plates, with

* These granules are not chlorophyll-vesicles, as in Vaucheria, Chara, &e.,
they have more the aspect of dense, mostly longish granules, without auy
enveloping membrane. When the chlorophyll is extracted by spirits of
wine, these, like the remainder of the contents, become bleached, but remain
distinguishable ; the shape, however, becomes irregular through the action of
the spirit.

REJUVENESCENCE IN NATURE. 263

a more or less brownish tinge, sometimes appearing wholly
filled with granules, sometimes displaying a lighter space,
free from granules, in their centres. In correspondence
with the shape and the (in the same mother-cell) tolerably
equal size of the plates, they are so arranged that mostly
six are grouped round a central one. ‘The size of the
plates varies according as they are to form macrogonidia
(net-formers) or microgonidia (swarmers); in the former
case the diameter amounts to about „;;th millim., in the
latter to jth or {,th; the latter, moreover, exhibit a less
regular, more oblique shape, and less numerous (only
4—10) chlorophyll granules. The membrane of the
parent-cell begins to thicken by swelling-up in this stage.
In the third stage, finally, is effected the complete
separation of the little plates, and the formation of the
gonidia. The plates, already previously clearly defined
against the light intermediate streaks, begin to round off
at the corners, and to become convex at the surface,
previously lying flat against the cell-membrane, so that
the tabular form passes, not at once into a globular, but
into a lenticular form, which compression may still be
observed in a slight degree subsequently, in the stage of
motion. During this rounding, the lighter intermediate
streaks vanish, the gonidia come into direct contact,
triangular intercellular spaces only appearing at each
point where three meet. This stage is ordinarily of ver

short duration, passing at once into the fourth, that of
the movement of the gonidia, which differs in degree and
duration, according to the kind and destination of these.
Although the phenomena of the motion of the gonidia of
‚Hydrodictyon have been spoken of already, we cannot
pass them over entirely here, since certain points come
under consideration in ıt, which have an influence on our
judgment respecting the mode of cell-formation which we
are now engaged with. Both in the macrogonidia and
microgonidia the movement at first presents a mutual,
originally scarcely perceptible crowding and pushing,
which, when in full course, is comparable with the move-

264 THE PHENOMENON OF

ment of a dense crowd of people in which no one can
leave his place. The signal for freer and more active
motion is given by the processes taking place about, this
time in the membrane of the mother-cell. The cell-
membrane has begun to thicken even in the second stage
of the formation of the gonidia, and the swelling-up
made still further progress in the third, but the resist-
ance of the cuticle hinders the extension of the circum-
ference of the cell-membrane. This obstacle is now
removed by the cuticle cracking, first in one, and soon in
several places, which gives the cell-membrane, now
becoming soft and limp through the swelling-up, room to
expand. This is the epoch in which the movement of
the gonidia changes, either simultaneously throughout
the cell, or more frequently gradually spreading from the
spot where the first dehiscence of the cuticle occurred,
into a lively trembling and jerking, which Treviranus not
inaptly compares with the ebullition of boiling water.
But even in this very rapid motion the actual locomotion
of the gonidia is extremely slight, so that, for example,
free spaces, such as occur in cells where vacuities existed
in the mucilaginous layer, are not filled up by gonidia.
In the macrogonidia, destined to form nets, the motion
stops here; in the microgonidia, on the contrary, a
whirling is added to the trembling motion. While,
namely, up to this time, the whole mass of microgonidia
had retained their peripherical position, representing as a
whole the form of a sac, corresponding to the form of the
mucilaginous layer, even in their movement, this strange
bond is now dissolved, the gonidia leave the periphery,
and whirl about in varied intermixture through the
whole cavity of the cell, till at length, through the
bursting of one or more bulging protrusions of the cell-
membrane, they leave the cell in a dense swarm, and
continue the swarming motion for a long time in freedom.
Both the macrogonidia and microgonidia exhibit various
peculiarities, during the period of motion, which were
not perceptible before its commencement, ‘The macro-

REJUVENESCENCE IN NATURE. 265

gonidia retain their roundish or rounded polygonal form,
but exhibit at one side a hyaline margin, which occupies
abouf a third part, or even half of the circumference ;
the microgonidia, on the other hand, become distinctly
longish, the more acuminated end, at the same time,
appearing transparent. ‘The green granules enclosed in
the interior are still distinguishable in both, but less
sharply, since they begin to blend together; the colour
is again bright green, in the net-formers darker, in the
swarmers more of a yellowish-green. The fifth stage,
that of rest, is connected in the macrogonidia with their
union into a young net, which union begins even in the
last period of the movement, so that gonidia, already
united in groups, are seen still jerking and pulling back-
wards and forwards. When they have come to complete
rest, and united perfectly into a new net, the elongation
of the previously roundish gonidia begins; the green
granules in their interior become completely blended into
a homogeneous mass; the rudiment of the first starch-
grain makes its appearance ; the newly formed cell-mem-
brane becomes distinguishable. 'The microgonidia, also,
which swarmed-out, and which never unite into nets, but
merely become irregularly heaped together, exhibit, after
they have come to rest, this transition of the granular
contents into a homogeneous green mass, as well as the
formation of a small starch-grain and the production of a
distinct cell-membrane, by means of which they often
become coherent together in groups; on the other hand
they show no trace of elongation, and in general do not
increase in size,* while in the young nets the increase of

* I cannot let this opportunity pass without mentioning one observation,
which perhaps somewhat modifies what has been said above. In the vessels
of water in which I cultivated Hydrodictyon I frequently found isolated
Hydrodictyon-cells, in groups of four united irregularly together, which
became developed, but under these circumstances assumed irregular, bulging,
nodulated, or even branched forms. Whether these hermits arose from
individual microgonidia, which, as an exception, had arrived at a develop-
ment, or from macrogonidia scattered through accidental rupture of the
mother-cells in the stage of motion, I could not decide by direct observation,

266 THE PHENOMENON OF

size advances with astonishing rapidity, the cells of the
net, under favorable circumstances, increase to 600 times
the length, and 240,000 times the volume in the course
of a few weeks.*

After this description of the processes taking place in
the course of the formation of the gonidia of the Water-
net, it is not difficult to perceive its similarity to other
modifications of cell-formation by division. Seeking, in
the first place, the import of the light spots which
characterise the first stage of the new cell-formation of
the Water-net, it is beyond doubt that they represent the
centres of so many new cells, consequently are either
actual nuclei, or, since we cannot detect any defined
outlines, accumulations of albuminous substance analo-
gous to nuclei. The net-work of granules between the
light spots, occupying the boundary-lines of the future
gonidia, reminds us of the formerly mentioned production
of a zone or plate of granules, appearing in the division
of the mother-cells of pollen, as also of the zones of
granules in the mother-cells (asci) of the spores of
Peziza, and shows that the regions becoming parted off to
form new cells are in contact at first. The light streaks
which are displayed in the second stage, between the
concentrating and isolating tabular portions of the con-
tents, appear to be formed bya secreted matter, which is
immediately re-dissolved and destroyed, but which effects
the solution of continuity between the individual gonidia,
and between them and the membrane of the pareut-cell.

but the latter seems to me more probable. I have also observed similar
hermits in Pediastrum.

* The entire development of the Water-net to the period of repetition of
the formation of gonidia, is completed in about 3—4 weeks in cultivated
specimens; in the wild state, with more vigorous vegetation, a longer time
may perhaps be necessary. The size of the cells at the period of the pro-
duction of the net, at which time their shape is almost globular, amounts to
145 millim.; the fully developed cells frequently exhibit, in the wild state, a
length of 5—6 millimetres, a thickness of §—} mill.; when cultivated in-
doors, on the contrary, they attain only 1—13 mill., in subsequent genera-
tions even only 3—} mill. in length, but the propagation, nevertheless,
happens at the proper time.

REJUVENESCENCE IN NATURE. 267

Perhaps it is the same substance in a state of solution,
but still viscous, which retains the active gonidia for some
time at the periphery of the cavity of the mother-cell, so
that the macrogonidia, in which the stage of rest and
mutual attachment begins pretty soon, cannot unite
otherwise than in the tubular form given by their mode
of origin, into a net-like colony. We sometimes perceive
in the interior of newly-formed nets, still enclosed in the
membrane of the parent-cell, colourless balls of muci-
laginous consistence, without distinct outlines, which are
coloured yellow by iodine. In the swarm-like escape of
the microgonidia, through the burst dehiscence-sacs of
the mother-cell, likewise, we sometimes see the swarm
interrupted by a mass of mucilage mixed up with and
clogging them. Whether these masses of mucilage are
the still undestroyed remains of the above-mentioned
secreted connecting substance of the gonidia, I do not
venture to decide. Ordinarily, after the complete for-
mation of the gonidia, the contents of the mother-cell
exhibit, besides the gonidia, nothing but water-clear
fluid.

As a proof that the gonidia of the Water-net do not

originate free in the contents of the mucilaginous layer,
but separate from one another by mutual demarcation of
boundaries, out of an originally continuous mass, I may
mention the not unfrequent occurrence of twin-gonidia
(even of triple groups) in which, on swarmers, two (or
three) ciliated points may be distinguished, which are
sometimes side by side, sometimes placed at right angles
to each other, or are even on directly opposite sides. It
is easy to make certain that such forms are not produced
by blending of previously separate gonidia, but that the
light line of division, as formed in the second stage, is
omitted between the two plates or groups of contents ;
that, consequently, the mutual external definition be-
tween two (or three) inwardly separated cells, has not, or
only imperfectly, been effected.

The formation of the gonidia of Ascidium (p. 128),

268 THE PHENOMENON OF

Cladophora, and probably also of Chetomorpha (p. 185),
agrees essentially with the mode of cell-formation here de-
scribed; moreover, judging from the statements of authors,
those of Endococcus (Nägeli, ‘Hinz. Algen.,’ p. 17) and
Bryopsis, in which genus the accurate tracing of the pro-
cess, especially in reference to the behaviour of the chloro-
phyll vesicles, would be especiallyimportant. The formation
of the gonidia, as well as the spores, of Saprolegnia,
likewise referring here, deserve a more minute exami-
nation, on account of their somewhat aberrant character.
The apices of the filaments, swelling up into longish clubs
or cylinders, and becoming shut off as separate cells, in
which the gonidia of Saprolegnia are formed,” are filled
at their formation with a granular mucilage. Subsequently
several cavities present themselves in the interior of the
mucilaginous mass, along the axis of the club, which
cavities, gradually increasing in size, become blended
into a single cavity traversing the entire tube, not, how-
ever, of very large size. The contents thus converted
into a thick parietal mucilaginous layer, soon acquire an
undulated surface, forming little rounded eminences,
which project more and more, while the intermediate
furrows continually cut in deeper until they at length
reach the cell-wall. In this manner the mucilaginous
layer becomes divided into numerous hemispheres, at-
tached by their flat sides upon the cell-wall; these,
however, immediately become rounded into globules,
separating simultaneously from the cell-wall. ‘This com-
pletes the formation of the gonidia, which immediately
commence their movement, continuing it for some time
after they have been expelled from the mother-tube.

* The formation of free sporangia in the interior of the swollen points of
the filaments, described and figured by Nägeli, (‘ Zeitschr.,’ 1847, p. 28,
t. iv, figs. 1—6,) is totally different from this. I have likewise seen it, so
rarely, ar that I could not trace the whole course. It seemed to me
not to belong to the sphere of the normal phenomena of development of
Saprolegnia, and is just as enigmatical as the occurrence of sessile globular
excrescences with rotating and subsequently repeatedly dividing contents,
observed in the same plant.

REJUVENESCENCE IN NATURE. 269

During the time they are in motion, the gonidia exhibit
a longish shape, in the transition to rest they re-acquire
the original globular form. The rest is followed im-
mediately by gerinination. All these processes, from the
formation of the clubs to the swarming out of the gonidia,
are the work of a few hours.* The occurrence of large
resting spores, which has escaped most observers,t is a
normal phenomenon in the later period of the existence
of Saprolegnia, occurring sometimes simultaneously with
the formation of the gonidia, usually, however, after that
is terminated. The spores are formed in globular or
pear-shaped, expanded cases, at the tips of slender
divaricated lateral branches ; the tips of the erect shoots
more rarely swell up into such bulging spore-cases. In
exceptional cases spores are formed also in cylindrical
terminal tubes, agreeing in form with the gonidium-
cases. ‘The mode of formation of the spores agrees in
all essentials with that of the gonidia. The granular
mucilaginous contents of the future spore-cases become
darker and more opake than those of the gonidium-clubs,
but, as in them, become applied upon the wall of the cell.
In this stage several large vesicles, arranged at regular
distances, make their appearance in the dark mass of the
mucilaginous layer.

When we compare the number and distance of these
vesicles with those of the future spores, it scarcely admits
of doubt that they are nuclei, from which proceeds the
formation of the spores, especially since we may often
distinguish a similar lighter vesicle in the developed
spores. The formation of nuclei is followed by the
production of elevations on the internal surface of the

* The statement of Meyen, (‘ Pflanzen-physiologie,’ iii, p. 457, t. 10, f.19,)
that the active gonidia are formed in separate mother-cells inside the club, is
incompatible with my observations. Perhaps the key to this difficulty lies
in the above-mentioned observation that the gonidia of Suprolegnia capituli-
Jera acquire a membrane shortly after birth, (see p. 188.) It is conceiv-
able that Meyen’s observation was made on another peculiar species in
which the gonidia acquire a membrane even before birth. x

+ I find it mentioned only by Schleiden, (‘Grundz., lte Aufl., ii, p. 36.)

270 THE PHENOMENON OF

mucilaginous layer. The somewhat distant elevations
become more and more rounded, and the mucilaginous
layer, drawing itself apart between them, becomes finally
wholly contracted into them. The hemispheres thus
formed are therefore not closely crowded, as in the
formation of the gonidia, but separated by largish inter-
spaces. The next process is the rounding and detachment
from the cell-wall, in consequence of which the spores lie
free and loose in the interior of the spore-case, and are
not scattered until this decays. The form of the spores is
always globular; the size varies in Saprolegnia prolifera
from 5 to 4, millim., while the gonidia in the stage of
motion are only „, milim. long; the colour is brown ; the
contents are at first finely granular, subsequently inter-
mingled with drops of oil; the membrane is at first
imperceptible, when fully developed thick and evidently
double. In the cylindrical spore-cases, the hemispherical
elevations are formed in pretty regular alternate order on
the two opposite sides of the cell-wall, so that they are
interposed like the teeth of two wheels or racks; but
the detached spores fall into a single linear row. In the
expanded cases the arrangement of the spores does not
exhibit any definite order. The number varies very
much according to the size of the cases. I have seen as
many as twenty spores in one case, while in many other
instances there were only four, three, two, and not very
unfrequently there was only one.

The formation of the spores of Zeptomitus lacteus
resembles that occurring as an exception in the cylindri-
cal cases of Saprolegnia; the spores detached from the
wall of the mother-tube are arranged in a single row.*
The formation of the spores in the sporangia of Coleo-
chete takes place in a manner similar to that in the

* Leptomitus lacteus is in every respect allied to Saprolegnia. The dicho-
tomous filaments are not articulated any more than those of Saprolegnia,
but only divided into sections by regular strictures; these sections have
been taken for closed cells. It is only in the fructification that isolated,
mostly terminal sections are actually shut off, swell up to some extent, and
become spore-cases. No active gonidia seem to occur.

REJUVENESCENCE IN NATURR. 271

globular cases of Saprolegnia. The spores are flat-
compressed, however, before their separation, longish
afterwards ; their colour is green at first, subsequently
brown. The number of spores in C. pulvinata amounts
to 5—8.

Finally, I mention here the formation of spores in
Spheroplea, already described (see p. 164),* as a case
which connects the two sections D. 1. and p. 2., the
formation of an indefinite abundance of new cells through
transformation of contents filling up the entire cavity of
the cell, on the one hand, and of contents excavated into
a parietal investment, on the other. Before the com-
mencement of fructification, the cell-contents of Spheroplea
represent a parietal investment, which, however, does not
maintain itself as such in the preparatory stage of forma-
tion of the reproductive cells, as in the foregoing examples,
but collapses entirely, whence the spores produced by its
transformation are not seated upon the cell-wall even in
their earliest state, but lie free in the cavity of the cell,
arranged, according to the proportion of their size to the
diameter of the long tubular mother-cell, either in one
row, as in Sph. Leibleinüi, K., or in two or more, as in
Sph. Trevirani, K.t and Braunii, K. From the position
of the spores, it would be more correct to apply the term
free cell-formation to this, than to the preceding cases ;
but even here it is the entire contents, with the mere
exclusion of a watery fluid, which break up into a num-
ber of newly individualised masses. That these masses
separate at their first production, only loosely fill the
mother-cell, and are little or not at all in contact, arises
from the condensation of the contents connected with the
formation of resting spores, and the abundant quantity of
watery fluid which is thus excluded. AI the more con-
sistent portions of the contents, the viscid mucilage, the
previously annularly arranged chlorophyll, with the

* (See also Fresenius, on Spheroplea annulina, ‘Bot. Zeitung.,’ 1851,

vol. ix, p. 241,—A. H.) N
+ Meyen, ‘ Pflanzen-phys., iii, t. 10, f. 17.

272 THE PHENOMENON OF

extremely minute green granules in it, as well as the
starch-grains* (not vanishing in the process of solution),
are taken up at the very first origin of the spores. They
are not gradually consumed, but enclosed in the first
structure, which also explains the phenomenon that the
spores do not commence with minute rudiments, and
gradually increase in size in the mother-cell, but, on the
contrary, are larger in the first epoch of their formation
than they are subsequently, when their mass has become
more condensed. Thus this case appears as a reformation
of the whole cell-contents combined with division,
peculiarly modified by the condensation of the newly-
formed cells, and the retraction from the wall of the
mother-cell connected with this, a retraction such
as we have also seen in reconstruction without division
in the spore of Gidogonium, or as we are acquainted with
in the family of the Zygnemacez (in the intermixture of
the contents of two cells to form one spore).

EB. PARTIAL RECONSTRUCTION THROUGH FORMATION OF
DAUGHTER-CELLS IN THE CONTENTS OF SURVIVING MOTHER-
cELLs.—This kind of cell-formation is distinguished from
all the preceding bythe circumstance that the mother-cell is
not lost in the reconstruction, but survives the formation of
the daughter-cells, the contents of the mother-cell being
only partially, not entirely, applied to the formation of new
cells. While in all the foregoing cases the newly-formed
cells appear as more or less considerable transformations
of the mother-cell, we behold here a re-production or
new-formation in the most complete sense, since the old
cell persists as such, in spite of the reproductions taking
place in it. In all the foregoing cases, nothing remains
of the mother-cell after the formation of the daughter-cells
but the inessential membrane ; here, on the contrary, we
see the daughter-cells enclosed in the living, undividedly
persistent contents of the mother-cell.

1. The daughter-cells originate (without a nucleus ?)

* Each single spore encloses several of the existing starch-grains in its
structure.

REJUVENESCENCE IN NATURE. 273

close to the cell-wall, against which they are firmly applied
during their completion —This is the character of the
formation of the germ-cells of Valonia described by
Nageli. In the long tubes, when full-grown measuring
; to li inch in length, of this unicellular marine Alga,
the organic contents form a thin investment to the wall,
while the large cavity is filled with salt water.* The
mucilaginous layer is beset with reticularly arranged
or scattered chlorophyll-vesicles. At particular spots,
especially at the bottom, more rarely in the apex of the
cell, are formed the germ-cells, sometimes singly, some-
times connected in groups. According to Nageli, they
originate as minute colourless globules, which acquire as
they grow an evident membrane and green granular
contents, chlorophyll-vesicles being formed in their in-
terior. The fully-developed germ-cells adhere as flattened
disks to the wall of the cell. Those which occur at the
upper end of the mother-cell usually germinate in the
still surviving mother-cell, breaking through its mem:
brane, probably locally softened, stopping up the orifices
again with their bases. The peculiar ramification of
Valonia arises from this growth of the young individuals
out of the old one. The germ-cells at the lower part of
the tube, remaining undeveloped, probably only become
free through the decay of the parent individual, to be-
come developed as separate individuals forming new
family-stocks. The case here mentioned is distinguished
from the mode of cell-formation minutely described in
Hydrodictyon, under D. 2, by the circumstance that only
particular points, and not the whole of the parietal
mucilaginous layer, passes into new cell-formation ; more-
over that the new cells exhibit a gradual increase in size
in the surviving mother-cell, while in Hydrodictyon they
attain at their first production the full size which they
are destined to acquire inside the mother-cell. Nageli’s
description affords no information as to the behaviour of

* ¢Neueren Algensyst.,’ pp. 155—157, t. ii, f. ae
1

274 THE PHENOMENON OF

the chlorophyll-vesicles on those parts of the wall of the
mother-cell where the formation of the germ-cells occurs.

Botrydium doubtless belongs to the same family as
Valonia. My observations on the formation of the germ-
cells of this genus, already mentioned (pp. 128, 193), are
not sufficiently complete to decide whether it can be
properly cited as an example here. In Botrydium the
germ-cells are sessile all over the inside of the wall of the
vesicular epigzeous portion of the cell, placed pretty close
together, yet not in contact. ‘They exhibit a rather con-
siderable difference of size in the same individual, which
seems to indicate a growth inside the mother-cell., Simul-
taneously with their completion the mother-cell swells up,
softens, and collapses. According to Kützing,* however,
the spores often germinate before the collapse of the
mother-cell, breaking forth on its surface as a granular
coating.

2. The daughter-cells (mostly several, rarely only one)
are formed (around nuclet) free in the contents of the
mother cell.—The, term “ free cell-formation,” which
certainly meets most of the modifications to be examined
here, has hitherto been applied to many other kinds of
cell-formation already treated above. Looking at the
mere words, we may use this expression in two very
different significations, according as we intend to call the
cell-formation free in its result or in its origin. In the
first sense we speak of free cell-formation in contrast to
the formation of connected tissue, under which circum-
stances the daughter-cells may stand originally in most
intimate contact with the mother-cell and with each other,
but not be grown together, or not so firmly that they
cannot finally become free by the rupture or resorption of
the mother-cell. We have seen such formation of free
cells under a. 2 (formation of the gonidia of (Edoyonium,
of the pollen-grains, &c.), B. 2 (formation of the gonidia
of Ulothria, Characium, &c.), D. 1 (Sciadium, Chytridium)

>

* On a new Botrydium, in ‘Nov. Acta.,’ xix, ii, 388, t. 69, 4.

REJUVENESCENCE IN NATURE. 275

D. 2 (Ascidium, Cladophora). Free cell-formation in the
second sense, in which it was used for instance by
Nägeli,* likewise comprehends two very different series
of cases, viz., either the origin is only so far free, that the
daughter-cells formed through the transformation of the
whole contents of the mother-cell (with or without division
of them), separate at the very moment of their consti-
tution, from the membrane of the mother-cell, by con-
traction of their mass, and separate from each other in
the same manner, as we have already examined under
A. 2 (formation of spores of Gidogonium), D. 2 (Sphero-
plea); or the origin is free even in relation to the
definition of the boundaries of the original mass of con-
tents from which the new cell is formed, the daughter-
cells being formed, not out of the whole contents of the
mother-cell, but out of the separate, unconnected portions -
of them. It is this last series of cases that especially
merits the name of free cell-formation, if this term is to
be retained; and then the circumstances whether the newly-
formed cells are applied upon the mother-cell (r. 1), or
not,—and, in like manner, whether they subsequently
become connected together into a continuous tissue (as
we shall see in the endosperm-cells), or not,—are to be
regarded as less essential.

a. A free daughter-cell is formed around the primary
nucleus of the mother-cell——The case here mentioned
differs from those examined under A. 2, e. g. the formation
of the pollen-grain in its special mother-cell, in the cir-
cumstance that the daughter-cell does not take in the
whole of the contents of the mother-cell, but lies free in
the contents of the latter, so that other daughter-cells
may subsequently originate in the contents of the same
mother-cell. This strange and most rare case was

* Zeitschrift,’ 1846, p. 51, (Ray Translation, 1849, p. 123.) “In free
cell-formation a greater or smaller portion of the contents becomes isolated, or
even the whole contents of the cell. On the surface of this is formed a complete
membrane, altogether free at its outer surface, (in contact neither with the
wall of the mother-cell nor those of its sister-cells.)”

276 THE PHENOMENON OF

observed by Hofmeister in the embryo-sac of Funkia
cerulea,* and described in the following manner. About
the time of the opening of the flower, before fertilisation,
but after the germinal vesicles have been formed, a new cell
is formed around the still existing primary nucleus of the
embryo-sac, which cell only occupies a small portion of the
internal cavity of the embryo-sac, in its lower third. After
the formation of this cell the original nucleus becomes dis-
solved, and two or more nucleus-like structures appear
in its place in the daughter-cell, but no further cells seem
to be formed around them. The formation of this central
daughter-cell belongs to the many structures occurring
in the embryo-sac which vanish again very quickly. The
same observer describes a similar process in the endo-
sperm-cells of Ornithogalum sulphureum,t in which, after
.. they have become parenchymatously connected, a new
daughter-cell not filling up the mother-cell is likewise
formed around the still present primary nucleus, which cell
sometimes becomes doubled by division, and around which
still other free cells appear subsequently to be formed.

6. Several free daughter-cells are formed around newly-
formed nuclei.t—The nucleus of the mother-cell fre-
quently survives during the formation of free daughter-
cells of this kind, indicating persistent vitality in the
contents of the mother-cell by the mucilaginous radii
proceeding from it. The number of daughter-cells
appears never to be accurately defined. All the cases
referable here occur in the embryo-sac of the Phanero-
gamia, in fact, it is doubtful whether anything similar
occurs anywhere else in the development of plants. We
have to examine :

a. The formation of germinal vesicles—The embryo-
sac, or germ-sac, as it is termed, is the last cell of the

* Hofmeister, ‘Die Enstehung des Embr. der Phanerog.,’ p. 13, t. viii,

H
f. 8,9, 10. A similar phenomenon is described in Asphodelus luteus, p. 10.
tT L.c., p. 14, t. xiv, f. 17—19.
3% Hofmeister, |.c., p. 11, is especially to be consulted regarding the

origin of the nuclei themselves.

REJUVENESCENCE IN . NATURE. 277

mother-plant, the uppermost in the axial row of cells of
the ovule, destined to become the focus of the reproduc-
tion, the mother-cell of new individuals; the germinal
vesicles forming in it are the real rudiments of the new
individuals, the unicellular germs of new plants. They
are formed already before the period of the scattering of
the pollen, free nuclei originating in the upper part of the
embryo-sac (the end turned to the apex of the nucleus
and the micropyle), in which the protoplasm is principally
accumulated, around which nuclei soon appear sharply
defined masses of contents, which are, as it were, “cut
out” of the general mass of contents of the embryo-sac.
‘The number of germinal vesicles is mostly three,* rarely
more,f sometimes only two,{ and very rarely only one
exists, in which case, however, the larger number is indi-
cated at the earliest period of formation by their nuclei,
two of which disappear again without cells having been
formed around them.§ The newly-formed germinal
vesicles are roundish at first, but soon extend longitudi-
nally ; at first they are only slightly in contact, but as
they increase in size become crowded together more closely
in the upper end of the embryo-sac. Ordinarily only one
of them becomes developed into an embryo, this out-
stripping the others in growth even before fertilisation, |
or the latter even die away and dissolve about that
epoch.T At the period of fertilisation the germinal
vesicle destined to development presses its end lying next
the micropyle firmly against the inside of the wall of the
embryo-sac, against the outside of which the pollen-tube
is. applied, which double connection may go as far as
actual growing together. In other respects the germinal

* Hofmeister, 1. c., Sorghum, t. xi, f. 22, 23; Canna, t. iv, f. 3, 5;
Godetia, t. v, f.5.

T L.c., Funkia cerulea, p. 16.

1 L.c., Polygonum orientale, t. xii, f. 18—20.

§ L. c., Agrostemma Githago, t. ii, f. 20—22.

|| L. c., Zea Mays, t. xi, f.4; Godetia, t.v, .5, 6, and ‘Botanische
Zeitung,’ 1847, t. viii, f. 10, (@odetia.)

q L. c., Canna, t. iv, fig. 6.

278 THE PHENOMENON OF

yesicle remains wholly free during its development into
suspensor (vorkeim) and embryo, becoming developed
without any connection with the other phenomena of
cell-formation in the embryo-sac, even interfering with
and displacing and destroying them, so that it affords us,
not merely in its first formation, but also in its further
behaviour, the example of the freest and most inde-
pendent cell-formation which the plant exhibits.

ß. Formation of transitory cells in the embryo-sac.—
In addition to the germinal vesicles not arriving at
development, already mentioned, other cells are met with
in the embryo-sac which only show themselves for a
short time; free cells, which are dissolved again and
vanish without leaving a trace when scarcely formed, or
even before completion, as mere nuclei. Among these
are especially the cells presenting themselves at the lower
(chalazal) poytion of the embryo-sac, agreeing more or
less in number and form with the germinal vesicles, but
never developing into embryos, and which are described
in Hofmeister’s often-cited essay in the majority of the
plants investigated by him.* ‘These strange antipodes
of the germinal vesicle originate either simultaneously
with the latter, or somewhat later, and, in exceptional
cases, even earlier ;{ they mostly disappear again before
fertilization,§ often even as mere nuclei; in rarer cases
they persist for some time after the fertilization, and
vanish during the formation of the endosperm-cells. |

Formation of the endosperm through free cell-
formation in the embryo-sac.—The vitality of the embryo-
sac is retained uninjured as a whole, in spite of the

* They appear to be absent from Polygonum orientale, (t. xii, f. 18, 19),
Agrostemma Githago (t. ü, f. 18—22) Godetia, (t.v, f 4, 5); they are
especially numerous in Sieyos (t. xili, f. 3—5); often only a single one, but
of unusual size, presents itself in Hyacinthus orientalis (t. vi, f. 8).

+ L. 6, Orchis, t. ii, f. 2, 3, 4.

I L.c., Crocus, t. iv, f. 14.

$ L.c, Zebalium, t. xiii, f. 6—9.

| L. e., Hyacinthus orientalis, t. vi, f. 4,5; Helianthus annyus, t. xül,
f. 18—20.

REJUVENESCENUE IN NATURE. 979

formation of germinal vesicles and transitory cells taking
place in both its ends; its primary nucleus ordinarily
survives,* or even increases considerably in size after
the formation of the germinal vesicles. The nucleus of
the embryo-sac is only dissolved during or shortly before
the period of fertilisation, and then a profound recon-
struction commences in the interior of the embryo-sac,
expressed in the production of daughter-cells, likewise
free,t but so numerous that they soon exhaust the inde-.
pendent life of the former, and the entire cavity becomes
filled up by the cohering newly-formed cells. ‘The tissue
produced in this way is the endosperm, or, as it is called,
the albumen of the seed, in which the developing embryo
of the new plant then becomes imbedded. ‘The en-
dosperm-cells, like the germinal vesicles, originate as free
nuclei in the fluid of the embryo-sac,§ which subsequently
become surrounded by masses of contents and clothed
with membranes. The cells thus formed very soon com-
bine into a continuous parenchyma, in which there is no
longer evidence of the origin from free cells.|| The
cellular filling-up of the embryo-sac with endosperm-cells
is not however completed at once, but proceeds gradually
from the periphery to the centre, the successively formed
endosperm-cells applying themselves in layers upon the
inside of the wall of the embryo-sac.T The formation of

* L.c., Sorghum, t. xi, f. 22; Hyacinthus, t. xiv, fig. 2; Zrodium, t. iii,
£.17; Helianthus, t. xiii, f. 17. More rarely the nucleus of the embryo-sac
oa before the formation of the germinal vesicles, e. g., in Orchis, t. i,

. 32.

T L.c., Agrostemma, t. ii, f.18—22; Bartonia, t. ii, f.34—40 ; Fritillaria
imperialis, t. viii, f. 6—9.

+ The rarer case of formation of endosperm by cell-division has been men-
tioned previously, (p. 248.) 2

§ See Hofmeister’s figures of Godetia, (‘Bot. Zeitung.,’ 1847, t. viii,
f. 25, a;) Fritillaria imperialis, (* Enstehung des Embryo,’ t. viii, f. 11;)
Bebalium, (l. ¢., t. xiii, f. 11;) Helianthus, (t. xiii, f. 20;) Linum, (t. xiv,
f. 4, 8.

I = Schleiden, ‘Beiträge zur Botanik,’ t. vi, f. 69, 76, 77. (From the
albumen of Chamedorea Sehiedeana.) (See trausl. in Taylor’s ‘Sc. Mem.,’
vol. ii, p. 281, t. xv, f. 1—10.—A. H.)

{ See Schleiden and Vogel, ‘ Ueber das Albumen,’ ‘ Act. Nat. cur.,” xix,
ii, t. 42, f. 42, 43 (Letragonolobus purpureus,) and f. 49, 50 (Baptisia

280 THE PHENOMENON OF

these layers appears to take place with especial regularity
in the Graminacee. According to Hofmeister’s ob-
servations,* the nuclei imbedded in the mucilaginous
layer which lines the embryo-sac arrange themselves with
a certain regularity, becoming distributed at equal dis-
tances on the inside of the wall of the embryo-sac. As
a cell is formed around each of these nuclei, and on all
simultaneously, the embryo-sac becomes lined with a
layer of cells, the first of the endosperm. On the inside
of this a second layer of cells is soon deposited in a similar
manner; this is followed bya third, and so on. Leaving
out of view the lamellar repetition, this process of cell-
formation clothing the wall reminds us very much of that
examined under p. 2; the exhaustion of the contents of
the embryo-sac (7. e. the mother-cell) occurring with the
formation of the last, innermost endosperm-cells, is related
to». 1.

When we consider the whole of the phenomena of
cell-formation in the embryo-sac connectedly, we behold
the case, unique in its kind, of a mother-cell in which
different kinds of daughter-cells are produced at different
periods. None of these daughter-cells belong any more
to the tissues of the mother-plant ; all, as cells originating
free, are in a certain sense reproductive cells, new indi-
viduals ; but of the many sisters, only one, the first-born,
is ordinarily destined to become perfectly developed,
while the majority of the others are compelled, in their
earliest childhood, to perform nursing-service to the
chosen one. The difference of the cells formed in the
embryo-sac may indeed be compared with the occurrence
of bimorphous, partly fertile, partly sterile gonidia in
the Alga; the parenchymatous conjunction of the ori-
ginally free endosperm-cells reminds us of the regular

combination of the previously free gonidia of Hydro-
dictyon and Pediastrum.

exaltata;) also Hofmeister, 1. c., t. xii, £25 (Polygonum orientale;) and
t. xiii, f. 21, (Helianthus annuus.)

* Lic, p. 30, t. xi, f. 25, 26, 29, (Sorghum bicolor.)

REJUVENESCENCE IN NATURE. 281°

Nägeli* treats, in the section on free cell-formation, the
phenomena of abnormal cell-formation, which are ob<:ved
in decaying contents of old cells. The mode of formatica
of these abnormal cells certainly agrees most of all with
the cases last discussed, but has thc peculiaiity that the
new structures escaping the sol; and decay of the
rest of the cell-contents are incapa'sic of development, or
only of abnormal development, descending into diseased
structures or pseudo-organisms. The character of these
abnormal cells is most varied and changeable; especially
remarkable is the occurrence of globular, resting, spore-
like cells (e. 9. in old Closteria),t as also the appearance
of active, Infusorioid structures, which occur not unfre-
quently in the interior of decaying cells of green fresh-
water Algze (e. g. Gdogonium, Spirogyra),t and are dis-
tinguished from. normal swarming-cells ‘by their irregular
form, varying size, slower motion, and mostly brownish-
yellow contents, succeeded by hyaline, finely granular
mucilage. In Spheroplea I have often seen such pseudo-
gonidia formed in the same cells with normal spores.
Abnormal structures of this kind have doubtless often
been confounded with the normal reproductive cells of
the Alge. The future will certainly unfold many. in-
teresting phenomena in this hitherto little-worked field.

In the preceding summary of the modifications in
which the process of Rejuvenescence of cells. advances to
new constructions, we have seen division of the cells
occur as a very ordinary accompaniment of the recon-
struction, and this in manifold ways. With these. pro-

* © Zeitschrift,’ 1847, p. 24, t.-ili, f. 1—3 (Bryopsis Balbisianum.) (Ray
Society’s transl., 1849, p. 98, t. ii, f. 1—3.—A. H.

+ Meyen, ‘Pflanzen-phys.,’ iii, t. 10, f. 24, (also figured by Focke,
‘Physiol. Studien,’ pl. iii, f£. 12.—A. H.) : j

+ (See Pringsheim, on Spirogyra, Transl. in ‘ Annals of Nat. Hist.,’ 2d
series, vol. xi, p. 210. Also consult on this point Itzigsohn, ‘ Bot. Zeit.,’
1853.—A. H.)

282 THE PHENOMENON OF

cesses of division are connected, in the first place, the
development of the tissue with its varieties, even the
development of the contrasts of the external organs (in
the higher plants), and, lastly, the multiplication of the
individuals, both through vegetative increase, and through
true reproduction. The formation of free reproductive
cells, may also be termed division, in so far that their origin
depends upon a parting of the contents of the mother-
cell. In opposition to this effort towards division and
separation, towards the development of multiplicity, both
from the repetition of the like and the shaping out of the
various vital tendencies in structures of many kinds—the
plant manifests, on the other hand, in certain periods of
conclusion and transition, an effort toward reunion of the
divided, either by gathering up and combining the
homogeneous, or: bringing together opposites. In the
higher divisions of the vegetable kingdom we meet with
this phenomenon in many forms. The intimate com-
bination of the organs at the higher steps of the meta-
morphosis, the fusion of parts in the individual whorls of
the flower, adherence even of entire whorls to each other,*
but in particular the blending of the carpels into closed
germens, exhibit the effort at reunion of the separated in
the morphological field, as the phenomena of fecundation
do in the physiological. But even in the lowest plants,
which do not possess the variety of organs and the con-
trast of sexes, whose whole cycle of vegetative life is
limited to the development of a single cell, or a series of
similar cells, we find acts of this uniting and collecting
vital tendency. Among the principal of these is the
phenomenon occurring in the Alge and Fungi, to which
the name of conjugation of the cells has been applied; a
phenomenon which always occurs at the close of the vegeta-
tive development, ordinarily at the termination of a series
of unicellular generations produced by dividing-increase,
and is for the purpose of forming, directly or indirectly,

* Whence arise the perigynous and epigynous insertions.

REJUVENESCENCE IN NATURE. 283

reproductive cells, the transition-cells to a new vegetative
eycle.* In the preceding summary of the conditions of
cell-formation, I have purposely avoided mixing up those
caused by conjugation; as the opposite of all kinds of
cell-formation combined with division, they deserve a
separate examination, through which, from the insuffi-
ciency of most of the descriptions of the cases belonging
here, I purpose, at the same time, an attempt at placing
the subject in its proper light (Orientirungs-versuch), to
guide in future investigations. In the following collo-
cation we restrict the idea of conjugation to those cases
in which: 1, two previously really separate cells unite ;+
2, the combination takes place by actual anastomosis, not
by mere application together of the cell-walls;{ 3, an
immediate intermixture of formative cell-contents occurs. §
Thus, in-true conjugation, two previously separate cells are
united in such a manner that in the combined state they
‘ can only be regarded as one cell, the two halves of which
sometimes remain distinguishable, connected by a narrow
isthmus or by a canal (trabecula), but sometimes coalesce
so completely that the earlier boundaries entirely disap-
pear. In such union, either all parts of the combining
cells (membrane and contents) enter into conjugation, or
the cell-membrane, and then either the whole or only the
outer, remains out of the combination, bursting so as to
let the inner membrane or merely the contents (with the
primordial utricle) conjugate. In this case it may happen
that the contents divide within the cell-membrane shortly
before the conjugation, so that two cells are formed

* See above, p. 132. (Diatomaces); pp. 133—135, (Desmidiacex,
Zygnemacee.)

iz This excludes the phenomena in the formation of the spores of Melosira,
Gidogonium, and Bulbochete, subsequently to be examined more closely, which
have been mixed up with conjugation.

{ This excludes the mere application of other cells upon the mother-cell
of the spores, such as occurs in Coleochete and Suprolegnia, as also the
union of the pollen-tube with the embryo-sac,

§ This excludes the anastomosis of the colourless cells of the leaves of
Sphagnum, Dicranum glaucum, and certain other white-leaved Mosses, as
also the union of long tubular spiral-fibre-cells to form vessels.

284 THE PHENOMENON OF

through double conjugation of the contents of two
dehiscing mother-cells, which extrude their contents.
The conjugation-cell formed in either of these ways, is
either itself a reproductive-cell, or the latter is formed by
a further metamorphosis of the combined contents within
the conjugation-cell, and this mostly takes place either in
one of the halves of this, or in the connecting piece
between the halves; it is mostly a resting spore, more
rarely an active gonidium, rarest of all the combined
contents divide into a number of cells in their transforma-
tion for the purpose of fructification. These, and other
less essential differences, produce the multiformity of
cases in which the phenomenon of conjugation presents
itself, especially in certain families of the Algze, while as
yet it has only been observed in one genus of the Fungi,
here, however, in a modification deviating from all tlıe
rest. In the following summary I shall endeavour,
as far as possible, to place all the known examples.

A. CONJUGATION OF SIMILAR CELLS.— The uniting cells
may be either free and isolated, as in most Diatomacex
and Desmidiacez, or they may be links of a many-celled
filament, as in the Zygnemacez. In isolated cells the
union mostly takes place by the sides of the cells, either
by parallel or by crossed approximation (copulatio
lateralis parallela, s. decussata) ; very rarely by the apices
of the cells (copulatio apicalis). In the jomted (many-
celled) filaments the union takes place either by each two
successive cells of the same filament anastomosing with
their adjacent ends by lateral processes, which we will call
chain-union (copulatio catenativa) ; or by the links of two
different filaments (or, as may equally happen, different
parts of the same filament overlying through bending),
uniting by their sides: yoke-union (copulatio conjugativa),
in which case the cells may be either bent like a knee in
order to reach each other (comjugatio genuflewa), or be
united without bending, by processes growing out to
meet each other and coalescing into a transverse canal:
ladder-like union (copulatio scalaris). These distinctions,

REJUVENESCENCE IN NATURE. 285

however, are less essential than those on which the fol-
lowing subdivisions are founded :

1. The conjugating cells unite entirely (with membrane
and contents), and, completely coalescing without throwing
of a membrane, form a seed-cell (spore).—The spore
originates here as the direct result of conjugation, not
subsequently through a further transformation of the
contents after the conjugation; the conjugation-cell is
itself the seed-cell, and does not produce the latter as a
new cell within itself. Here refers Palmoglea, the
remarkable, of its kind unique,* conjugation of which
was only represented in its commencement by Kützing,f
described in its further course by Thwaites, but, since he
assumed an absorption of the cell-membrane of the com-
bining cells, mistaken by him exactly in its most essential
peculiarity,f I have mentioned my own observations on
the conjugation of Palmoglea above;§ the minute
description of the process, with remarks on the species in
which the observations were made, will follow in the
description of the plates.

2. The conjugating cells, leaving behind the outer
membrane, unite directly to form a reproductive cell._—
The occurrence of this case is not improbable, but has
not yet been made out with certainty.

3. The conjugating-cells combine merely their contents
(bounded by the primordial utricles), to form the repro-
ductive cell; the dehiscent cell-membrane is deserted.—
The conjugation of many Diatomacez|| very probably
belongs here. The mode in which, according to the

.* Similar cases occur in the animal kingdom, in the. Infusoria. See
Kolliker on Actinophrys Sol, in Siebold and Kölliker’s ‘Zeitschrift,’ 1849,
b. i, p. 207, (Transl. in ‘ Quarterly Journal of Microscopic Science,’ vol. i,
p- 98, et seg,) The forms figure as Actinophrys difformis, by Ehrenberg,
(‘Infusionsthierchen,’ t. xxxi, f. 8,) doubtless represent conjugating states
of Actinophrys Sol.

7 Assuming that his Palmoglea Meneghinii, (‘Tab. Phyeol.,’ 24, iii,)
actually belongs to this genus, and not to Cylindrocystis.

f ‘Annals of Nat. History,’ 1849, 2d series, vol. iii, p. 243, t. viii, f. ¢,
(as Coccochloris Brebissonit.)

§ See pp. 135, 202, and pl. i, figs. 1—28, pl. ii, figs. 1—14. |] Seep, 132.

286 THE PHENOMENON OF

descriptions of Thwaites,* the cell-contents emerge from
the splitting siliceous cell- coats, and, speedily uniting
between the emptied shells of the mother- cells, acquire
the globular form, renders the assumption tolerably safe,
that the masses of contents unite here. No membranous
canal formed by an internal cell-membrane, inside which
the masses of contents unite, seems to exist here. Since
the conjugating individuals are always held together by
an abundant gelatinous secretion appearing at this time,
it is not difficult to conceive the persistence of the pair
of cells in their approximated position, even without the
formation of membranous tubes of conjunction. The
reproductive cells of the Diatomacex formed through
conjugation have no seed-sleep, but, although not active,
pass directly, in the manner of gonidia, into vegetative
development.

a. The contents of the two cells unite without previous
division ;—in this way one gonidium is formed by two
mother-individuals. Thus in Himantidium. t

6. The contents divide in both cells before the union
into two masses ;—in this case two gonidia are formed by
two mother-cells through double conjugation. According
to Thwaites’s representation, the division of the contents
preceding conjugation is transverse in Zunotia, crossing
the direction of division in vegetative increase.

a. The new individuals developed from the two
gonidia, soon surpassing the mother-cells in size, cross
the shells of the mother-cells. Thus in Zunotia tur-
gida.t

ß. They take a position parallel to the shells of the
mother-cells. Thus in Cocconema,§ Gomphonema,|| and
Schizonema.

4. The conjugating-cells unite with participation of

* ‘Annals of Nat. History,’ 1847, vol. xx, pp. 9, 343; 1848, ser. 2,
vol. i, p. 161.
Al waites, le, 1847, vol. xx, p. 22, f. 4, 1—7.
Ibid., t. iv.
Ibid., t, xxii, f. c, 1—3.
i Thid., t. xxii, f. B, 1—5.

REJUVENESCENCE IN NATURE. 287

the external membrane ; the reproductive-cell is formed
through contraction of the contents clothed by the internal
cell-membrane.—I'he formation of the reproductive-cell
(in the cases to be mentioned, of a spore) is consequently
here not a direct result of the conjugation, but it is
formed subsequently in the interior of the conjugation-
cell, in the strongly expanded isthmus of this. The deli-
cate.internal membrane, with the contents enclosed by it,
drawing itself out of the (on account of the thickness of
the outer membrane, rigid) extremities of the double-
cell, forms a seed-cell, at first cruciate-four-lobed, then
bluntly quadrangular, and finally globular, clothed by
amany-layered thickened membrane, within the persistent
four-horned conjugation-cell. From Ralfs’s representation
this is most probably the way in which the process is to
be understood in Cylindrocystis Brebissonii, Menegh.
(ex. p.)* The participation of the outer membrane in
the conjugation is beyond doubt; this is the principal
character distinguishing the genus Cylindrocystis from
Penium. The resemblance of the quadrangular internal
cell to that of Zetmemorus, in which this is undoubtedly
formed of a delicate cell-membrane, testifies in favour of
the existence of the latter in this case also. From the
cruciate or quadrangular shape of the spore, it may be
conjectured that the conjugation of genus Stauroceras,t
likewise belonging to the group of Closterina, as also
that of the Zygnemaceous genus Staurocarpus,t Hassall
(Staurospermum, Kg.), belong here.

5. The conjugating cells unite with participation of the
outer membrane; the reproductive-cell is formed out of
the mere contents, as a new cell, inside the mother-cell.
—This case (occurring in the majority of the Zygne-
macez) differs from the preceding by the non-participation

* Penium (Cylindrocystis) Brebissonii, Ralfs, ‘British Desmidiex,’ p. 153,
t. xxv, f. 6.

+ Ehrenberg, ‘ Infusionsth.,’ tab. vi, f. 94. Ralfs, 1. e., t. xxx, f. 4,
Stauroceras subulata, K. ;) ibid, £.3, (St. Acus, K.;) f. 5, (St. aeutum, Breb.)

+ Hassall, ‘British Freshwater Alge,’ t. 47—49.

288 THE PHENOMENON OF

of the inmost lamella of the cell-membrane in the forma-
tion of the reproductive cell.

a. With ladder-like (scalariform) yoke-conjugation.

a. The spore in the connecting canal or middle piece
of the double cell. In Zygogonium.*

ß. The spore in one half of the double cell (in the
cavity of one of the two conjugating mother-cells).
Ordinarily the case in Spirogyra,f and Zygnema.t

y. A spore in each half. This case occurs only as
abnormal in Spirogyra, and appears to depend upon an
incomplete carrying through of the conjugation, the
union-processes coming into contact, but not anas-
tomosing.§

b. With knee-shaped ( geniculate) yoke-conjugation.

a. The spore in the uniting canal or middle piece. In
Mesocarpus. ||

ß. The spore (or the gonidium) in one of the halves of
the double-cell. Here belong Sirogonium, with a spore
formed exactly as in Spirogyra,and the genus Mougeotia**
still enigmatical in its mode of reproduction, probably
possessing an active gonidium, leaving the mother-cell
directly after its formation.

c. Chainlike (catenate) union of the cells of the same
‚Rlament.

a. The spore in the lateral connecting-canal of the
conjugated-cells. This case is not yet known, but it is

* Vaucher, ‘Histoire des Conferves,’ t. vii, f. 3—4; Hassall, 1. c.,
t. 39.

+ Vaucher, |. c., t. iv and v; Hassall, 1. c., t. 18, 25, and 27—32.

+ Vaucher, 1. c,t.vi,f. 45 t. viii, f. 1, 2; Hassall, I. c., t. 38.

§ Vide Kützing, “Phye. General,’ t. 15, f. 1, 3, 4, 6 (of Spirogyra
quinina,

|| Hassall, 1. c., t. 42 —45.

4] Hassall, 1. c., t. 26.

** Hassall, (l.c., p. 172,) indeed, asserts that Mozgeotia is propagated by
zoospores, but gives no further information regarding their formation.
Vaucher (]. c., p. 79, t. viii) formed out of Mougeotia the section “ conjugées a
tubes intérieurs,” and describes the emergence of already elongated many-
celled young filaments from the old cells, a phenomenon which may he
explained as accidental development of gonidia remaining in the mother-
cell.

REJUVENESCENCE IN NATURE. 289

conceivable that Hassall’s strange Mesocarpus notabilis*
belongs here; this would require the assumption, that
the uniting canal, becoming filled with the contents of
the two conjugated-cells, pushed aside completely the
septum between them.

ß. The spore in one half of the double-cell (in the
cavity of one of the mother-cells). This is the case in
Hassall’s second division of the Spirogyre,t which
Kützing has distinguished as a peculiar genus, under
the name of Rhynchonema.}

d. Lateral, parallel union of isolated cells. —Here
belongs the conjugation of Closterium Lunula (see p. 140),
in which, according to Morren’s express statement,§
three different membranes take part in the formation of
the canal of union, an inner and an outer cell-membrane,
and a membrane (the primordial utricle) immediately
enclosing the green mass. The globular reproductive-
cell formed in the connecting canal, is an active gonidium,
which begins to revolve even while within the canal, and
soon breaks through the gelatinously swollen membrane
of the latter. Very often two approximated individuals
divide again and conjugate before they have become
completely separated: whence result conjugated double-
pairs.|| According to Ralfs’ description of the conju-
gation of Penium Jenneri, it resembles that of Cl. Zunula,
a large globular spore being formed in the interior of a
connecting canal, narrow at the points of issue, like
that of Mesocarpus.4

* Hassall, 1. c., t. 46.

+ Hassall, 1. c., p.152, t. 33 and 34; Nägeli, ‘Algensysteme,’ p. 151,
t. ii, f. 22—25.

£ ‘Spec. Alg.’ p. 443. The genus Rhynchonema, although based on a
very remarkable character, is scarcely natural, since both kinds of conjuga-
tion sometimes occur in one and the same species. I have observed this
especially in Spirogyra Weberi, in which, however, the chain-union is more
common than the yoke-union.

§ ‘Mém. sur les Closteries,’ ‘Ann. des Sc. nat.,’ 2 ser., v, 325, t. 9
(1836.) (See also Smith, on Closterium, ‘Annals of Nat. History,’ sec. ser.
vol. v, p. 8, t.i.—A.H.)

Morren, 1. c., t. 9, f. 22, 23, (Smith, 1. e.)
Ralfs, I. c., p. 153, t. 33, f. 2.
19

290 THE PHENOMENON OF

c. Conjugation of branched filiform cells by club-shaped
branches, which unite at their points.—The only known
example is the remarkable genus of Mildew Fungi
Syzygites, discovered and figured with a master’s hand
by Ehrenberg.* Erect, dichotomously branched, inar-
ticulate flocci, therefore unicellular filamentous little
plants, grow side by side in dense tufts. The uppermost
branches of the forks curve, like a pair of tongs, towards
each other, and send out (usually on the inner side of the
arms) clavate or pear-shaped branchlets. ‘I'hese fruit-
clubs, sometimes the opposite ones of the same fork,
sometimes those of different forks intermingled through
the social growth, unite by their apices. Ehrenberg
could not detect an actual anastomosis with certainty,
but it most probably does occur. In the middle of the
spindle-shaped conjugation-body thus produced, the
granular contents of the filaments ascend in a current
from both sides, and collect into a globular mass, which
becomes intimately combined with the membrane of the
middle-piece of the spindle, and shut off from the lateral
pieces by septa, and finally becomes free between the
two lateral portions, without these being torn. The
globular body becomes brown, and at length black,
during its development, and is a thick-walled cell, in
which, if we may put faith in Corda’s figure, free
spores are formed, imbedded in a soft amorphous
mass.

6. The conjugating cells, after dehiscence of the outer
membrane, unite through the inner ; the reproductive cell
is formed out of the mere contents, as a new cell inside
the conjugation-cell.—This is undoubtedly the condition
in the majority of Desmidiacee. The union almost
always takes place between isolated cells in this family ;
even in the genera with the cells connected into filaments

* “Verhandl. der Gesellsch. naturforsch. Freunde zu Berlin,’ 1 hand.,
p- 98, t. ii, ili (1829.)

+ Corda, ‘Prachtflora Europaischer Schimmelbildungen,’ (1839,) p. 49,
t. 23.

REJUVENESCENCE IN NATURE. 291

or ribands (Hyalotheca, Didymoprium, Isthmosira), the
conjugation does not commence until the filaments have
broken up into their individual links. In Bambusina
alone, according to Ralfs, occurs the case of isolated cells
conjugating with others still constituting links of con-
tinuous filaments, and thus becoming attached, like
parasites, upon the filaments. ‘The dehiscence of the
external cell-membrane is especially evident in TZetme-
morus and most Closteria; it always takes place in a
transverse direction, in the middle between two halves.
While the dehiscing outer membrane opens more or less
widely on one side (like the dehiscing cells of Zidoyonium),
the delicate internal membrane protrudes as a tubular
process, to unite with the corresponding process of the other
cell. If, at the same time, the internal cell-membrane
remains connected with the outer cell-wall, the halves of
the dehiscent cell-membrane mostly remain approximated
together and connected with the uniting canal and the
spore, which usually fills this up (e.g. in Closterium
acerosum, lineatum, &c.); but if the loosened internal
cell-membrane gradually extricates itself from the outer,
the halves of the latter become separated and are readily
thrown off (e. g. in Teimemorus).

a. Conjugation in a parallel position.—This is peculiar
to the group of Closterina. In the species with curved
cells the union takes place (with rare exceptions) by the
convex side, so that the conjugated specimens have their
points diverging.

a. The halves of the dehiscent cells separate from each
other all round, the internal cell-membrane entering into
conjugation gradually emerging wholly or almost entirely.
The spore formed from the contents lies loose in the
delicate conjugation-cell. This is the case most evidently
in Zetmemorus ;* according to Ralf’s figures, Docedium,t
and a section of the Closteria having longitudinally

* Ralfs, l.c., p. 146, t. 24, f. 3.
T Ibid, t. 26, f. 4.

292 THE PHENOMENON OF

striate and truncated ends,* seem to exhibit a similar
behaviour.

ß. The halves of the dehiscent cell only separate a
little on the side turned towards the other individual, at
which the internal membrane emerges, while they remain
connected on the outer side; the internal membrane
remains as an internal investment in the outer; the
spore mostly fills the uniting canal so completely, and is
in such close contact with ıts walls, that the latter is
scarcely distinguishable. This is the condition in Pensumf
(with the exception of the species mentioned previously),
and the unstriped Closteria} (with the exception of the
above-mentioned (7. Zunula).

Closterium lineatum§ also belongs here, but with the
peculiarity, known only in it, that ¢wo spores are formed
between two individuals. As I have had an opportunity
of observing the process of conjugation minutely in this
very species, || I am able to explain the mode of origin of
the really double spore (not two-lobed, as Ralfs terms it).
The very much elongated, only slightly curved specimens
of Clost. lineatum, lie close together in pairs before
conjugation, sometimes with both the convex sides in con-
tact, sometimes with the convex side of one touching the
concave side of the other. The cell-membrane dehisces
transversely, either simultaneously in both, or in one
earlier than the other, in the middle of the cell, previously
marked outside by an annular line, and inside by an
interruption of the green contents, but this takes place
in such a manner that the two halves only separate a
little on the side turned towards the other individual,
remaining connected on the opposite side, so that the

* Ralfs, l.c., t. 29, f. 2, (Closterium striolatum) ; fig. 6, 7, (Closterium
Juncidum.

r Ibid., t. 25, f. 1 and 5, Penium margaritaceum and truncatum.)

{ Ibid., t. 27, f. 2, (Clost. acerosum ;) t. 28, f. 4, (Closl. Leibleinii.)

§ Ehrenberg, ‘Infusionsth.,’ t. 6, f. viii, 4.) Ralfs, lc. p.174, t. 30, £.1.

|| In the middle of May, 1848, in specimens from the peat-holes of the
Mooswald, near Freiburg, especially rich in Desmidiacee.

4| The two pieces are mostly of unequal length.

REJUVENESCENCE IN NATURE. 293

cell becomes broken geniculately, though only at a ve

obtuse angle. The opening produced by the slight
dehiscence of the outer cell-membrane, forming a cross-
slit in one side, is immediately occupied by two thickened
projections of an internal cell-membrane issuing out.
‘These two thickened processes are the ends of two deli-
cate-walled daughter-cells, meeting in the centre of the
mother-cell, and which are probably formed by division
of the contents of the mother-cell very shortly before the
beginning of the conjugation. Since only these internal
cells enter into the conjugation, we have here, not, as
appears at first, a simple conjugation of two cells, but,
strictly speaking, a conjugation of two pairs of cells;

since, moreover, the two issuing processes, which unite
with the two coming to meet them from the other side,
are the exds of the two internal cells, Closterium lineatum
affords the rare example of a copulatio apicalis. The
individuals destined to conjugation lying near together,
the thickened projections do not grow out into long
processes, but apply themselves, in the form of everted
lips, directly upon the corresponding parts of the other
individual, or, if this has not yet pushed out its thickened
processes, upon its closed external cell-wall. This pro-
cess of the commencement of conjugation cannot be
described better than by comparing it to the contact of
four thickened firmly appressed lips in a kiss mouth to
mouth. The thickened projections are originally trans-
parent and almost colourless, since only a few green
granules can be observed in them, often in distinctly circu-
lating motion, entering at the back and retiring from the
front into the interior of the cell; the green contents
soon follow, however, in abundant quantity. The four
protuberances next become so densely filled with green
matter and pressed so closely together, that the coupling
growth and anastomosis taking place during this crowding
up cannot readily be traced, but it is clearly shown by
the result. Sometimes the delicate membrane of the
protuberance bursts under the pressure of the contents,

294 THE PHENOMENON OF

so that the latter become diffused, or form an irregular
accumulation between the two mother-individuals, which
of course frustrates the formation of the spores. In
normal development the whole mass of green contents
enters in a short time into the two connecting canals,
which swell up from the middle, where they are in con-
tact, out, in opposite directions, into obovate or almost
globular sacs, which wedge themselves in closely between
the four legs or horns of the conjugated individuals. In
each of these sacs the contents become balled into a
globe, which becomes clothed with a cell-membrane, at
first delicate and smooth, afterwards thick and granulated.
In this way, therefore, two spores are formed, completely
separate in their origin, which so closely fill up the deli-
cate sac-like canals of union in which they are formed,
that as they lie between the mother-individuals, they
appear like free globules, but are persistently connected
with the mother-cells by the empty and colourless lateral
parts of the two closely approximated uniting-canals,
which extend into the valve-like openings of two empty
shells. ‘These connecting pieces, formed from the inner
membrane, are readily distinguished, by their want of
colour, from the outer membrane or shell, which appears
straw-coloured after the contents are emptied out. A
not unfrequent abnormity affords a further proof of the
origin of the two spores through conjugation of opposite,
completely distinct pairs of cells; this is the occurrence
of only one spore between two mother-individuals. In
this case only two corresponding halves (or horns) of the
mother-individuals become emptied, while the two others
remain densely filled with green contents, which, in spite
of the dehiscence of the outer cell-membrane, cannot flow
out.

b. Conjugation in crossed (decussate) position.—This
occurs in the entire group of forms allied to Zuasirum,
and also in many genera formerly united with Des-
midium.

a. The halves of the dehiscent cells separate by an

REJUVENESCENCE IN NATURE. 295

annular slit, the protruded internal membrane entering
into the conjugation becomes very strongly developed.
The spores become free by the disappearance of the
enlarged saccate conjugation-cell; this also sets the
halves of the old cell-membrane free, from which the
internal membrane does not seem to be drawn out as in
Tetmemorus. This case occurs in Zuastrum* and the
genera intimately allied to, and difficultly separable from
it, Micrasterias,t Cosmarium,{ Xanthidium,! Staurastrum
(Phycastrum, K.)| The complete separation of the
halves of the mother-cell membrane does not, however,
seem to be constant, for Ralfs gives figures of the same
genera, and even of the same species, as those above
cited, which exhibit halves connected together at one
side.

6. The halves of the dehiscent cells separate only at
one side, in order to emit the connecting canal formed
out of the internal membrane, not expanded into a sac;
they do not become detached. The spores are formed
either in the middle of the connecting canal (as in Hya-
lotheca,** Bambusina,tt and Isthmosira (Spherozosma,
Ralfs),{{ or in one of the halves, in a manner similar to
that we have seen in Zygnema and most of the Spirogyra,
a case which is only known with certainty in Didymo-
prium§§ among the Desmidiacez, but perhaps occurs also
in the genus Desmidium.| ||

* Ralfs, 1. c., t. 12, (Zuastr. oblongum ;) t. 14, f. 5, (E. pectinatum,) &e.

+ Ibid., 1.6, f. 1, (Mierasterias denticulata, with the mace-like spores
beset with forked spines ; the conjugation itself is not represented.)

t Ibid, t. 16, f. i, (Cosmar. Botrytis;) f. 2. (C. margaritiferum) &e.;
Nageli has also described the conjugation in a species of this genus, his
C. rupestre, (1. c., p. 118, t. vii, f. 6)

$ Ibid., t. 18, (Xanth. armatum.)

|| Ibid., t. 20, £. 5, (8%. dejectum ;) t. 21, f. 5, (St. orbiculare ;) t. 22, f. 3,
(St. hirsutum ;) £.9, (St. polymorphum ;) t. 23, £.9, (St. brachiatum,) &e.

TE. g., of Cosmarium margaritiferum, t. 33, £.6; Cosm. Broomei, t. 33,
f. 7, Arthrodesmus Incus, t. 20, f. 4.

** Ralfs, 1. c., p. 53, t. 1.

Tt Ibid., p.59, t. 3, (as Didymoprium Borreri.)

tt Ibid., p. 67, t. 6, f.2 (I. excavata;) t. 32, f. 2, (T. vertebrata.)

§§ Ibid., p. 55, t. 2, (Didym. Grevillii.) ; ee

||| Ibid., t. 4, where Ralfs represents spore-like globules in the interior

296 THE PHENOMENON OF

7. The conjugation takes place with participation of
the entire membrane; inside the double-cell thereby formed
the internal membrane contracts into narrower limits,
away from the wall of the expanded isthmus, forming a
cruciform or quadrangular internal cell ; inside the latter
the contents contract again to form finally a globular
spore.—This case is required by the preceding as con-
clusion of the series. If we have placed Stawrocarpus
properly under 4, and if it be correct that, as Ralfs*
remarks, in passing, in the description of the conjugation
of Tetmemorus, there exists a species of Stawrocarpus in
which a globular spore is formed inside the quadrangular
cell by further contraction of the contents, this case does
really occur.

B. CONJUGATION OF DISSIMILAR CELLS.—I know of
no other cases to place in this entire second section, but
the conjugation of Vaucheria asserted by Nageli,t which
case, however, although I cannot but confirm Nageli’s
observations, is not yet placed beyond doubt in my
mind. A certain reciprocal action of the slender hook-
shaped sterile branchlets or horns as they are called
(the anthers of Vaucher), and the thick inflated lateral
branchlets which produce the spore in the extremity,
cannot well be denied. Even Vaucher{ described the
application of the former upon the latter, and figured it
in Vaucheria sessilis; Hassall observed that in those
species in which the spore-forming branchlets emerge in
considerable numbers from the base of a simple horn, as
in Vaucheria geminata, the spore-forming branchlets,
vice versd, apply themselves upon the horn, and subse-
quently remove again and curve backwards. According
to Nageli’s and my own observations on Vaucheria

of the cells of an unconjugated piece of Desmidium Swartzü. Might another
filament have been connected with this, and again detached after being
emptied P

* L. c., p. 146.

T See eMivenects p. 175, t. iv., f. 21, 22.

+ ‘Hist. des Conferves d’Eau Douce,’ (1803,) p. 17, t. ii, £. 7.

§ Hassall, 1. c., p. 49, .3, f. 1.

REJUVENESCENCE IN NATURE. 297

sessilis, after the separation of the horn from the spore,
the former appears open at the point, and a considerable
space, doubtless shut off as a separate end-cell before the
separation, empty; the spore is at this time likewise
surmounted by a more or less distinct tube, empty and
open at the summit, which undoubtedly is the open end
of the mother-cell of the spore. The open end of the
emptied end-cell of the horn on one side, the open end
of the mother-cell of the spore on the other, together
with the fact that the two were previously connected,
certainly render it very probable that this connection is
areal conjugation, that, therefore, the contents of the end-
cell of the horn are united with those of the mother-cell of
the spore to form the spore itself. The application of the
horn upon the spore-bearing branch ought then to take.
place defore the formation of the spore, on which point
my observations are deficient, but which is in agreement
with Nageli, figure 21.* However, on the one hand, the
circumstance is puzzling that many species seem to pos-
sess no trace of the said open tube surmounting the
spore,t while other species exhibit open tubes in the
spore-branchlets with no horns corresponding to them,
as, for instance, V. polysperma, Hassall,t with very
numerous, linearly arranged spores, but only very few

* See, on this point, Karsten on ‘ Conferva fontinalis, L.,’ in the
‘Botanische Zeitung,’ 1852, p. 89, ef seg., pl. 1, wherein he describes the
conjugation in all its stages.—A. H.

+ Thus, for example, in Vaucheria terrestris and hamata, in which, at the
same time, in spite of the strange position of the spore on the back of the
horn, an union of the inrolled point of the horn with the spore does occur,
as is represented very beautifully, and even with emptying of the end-
cell of the horn, by Thuret, (‘Sur les Org. Locomot. des Spores des
Algues,’ ‘Ann. des Sc. nat.,’ 2d ser., vol. xix, t. 15, f. 49, (1843,) in a form
doubtless belonging to V. hamata. In V. geminata the little tube above the
spore is likewise wanting, but Nageli has seen a scar on the summit of the
spore, which indicates the previous union with the horn, and indeed, accord-
ing to Hassall’s observations, not with the point but with the side of the
horn. The form of the horn in Y. erzeiata, (Vauch., 1. e., t. ii, f. 6,) nearly
allied to 7. geminata, is interesting, since two little side horns issue from
the principal horn, from their position evidently destined to union with the
two spores. A

+ L.c,t.4,f.6. Ihave observed this species also near Freiburg.

298 THE PHENOMENON OF

horns, which, moreover, as in Vauch. sessilis, exhibit an
empty open end-cell at the period of maturation of the
spores. The genus Vaucheria, which has already so much
occupied naturalists, still requires, therefore, further and
more minute investigations in reference to the formation
of its reproductive organs. In conclusion, I will mention
certain other cases which bear some resemblance to the
phenomena of conjugation, and have been, in fact, really
regarded as such. In Saprolegnia, which exhibits so
much likeness to Vaucheria in morphological respects,
we find a structure similar to the horns of Vaucheria.
At the period of the formation of the resting-spores,
between the lateral branches swelling up into pear-shaped
spore-cases, appear frequently, but not constantly, slender
vermiform branchlets, which, when they reach the spore-
cases, apply themselves firmly upon these, and indeed
sometimes twine round them in irregular coils ; no actual
anastomosis takes place however. Coleochete pulvinata
(see page 161) exhibits a phenomenon which may be
compared with this. The sporangium of this species
originates by the expansion of the last or last but one
cell of a filament, and is, in itself, a simple cell, which,
however, acquires a most complete cellular envelope
through the close application upon it of cellular branch-
lets, partly arising from the cell immediately preceding it,
partly reach over like bridges from branches situated lower
down or neighbouring filaments. 'I'he direction, differing
from the ordinary erect growth, in which the branches
combining with the sporangium come in from all sides,
sometimes horizontally, and sometimes even descending,
shows, although there may not be so intimate a connec-
tion and so direct a co-operation for the formation of the
spore as in conjugation, that there is, nevertheless, here,
a similar reciprocity of attraction and seeking-out of the
parts, as well as a material assistance in the spore-
formation, through the connection of the mother-cell of the
spore with the numerous smaller cells forming the enve-
lope, doubtless effected through the process of endosmose.

REJUVENESCENCE IN NATURE. 299

Distant as the physiological importance of these pheno-
mena of application just described stands, from the appli-
cation of the pollen-tube on the embryo-sac, and through
the medium of this, on the germinal vesicle, connected
with the fertilisation of the Phanerogamia, the resem-
blance between the processes of the two phenomena is
unmistakeable.

Some of the Diatomacez afford another case, to be
placed here as it were in an appendix, which perhaps
might be regarded as an instance of arrested conjugation.
While I have seen in many genera of this family an
actual conjugation of completely separate cells (p. 286),
in the group of the Melosiree the large reproductive-cell
which commences the new series of generations (the
sporangium,* as it is termed), is formed out of the con-
tents of a single grown-out cell, the shell or membrane of
which, dividing in the middle, separates to allow space
for the expansion of the newly-formed, more vigorous
primary-cell. Thwaites,t who describes this process in
several species, thinks that it may be brought into
agreement with the conjugation occurring in other
groups of the same family, by assuming the division of
the contents of the mother-cell into two portions pre-
viously to the formation of the new cell, these portions,
instead of developing into separate cells, as in the vege-
tative increase by division, combining together again im-
mediately in order to produce the reproductive-cell.
Although this hypothesis is not yet substantiated by
direct observation, it deserves attention, since it opens
a common point of view for the phenomena of reproduc-

* See p. 141, note. .

T See Thwaites, ‘Further Obs. on Diatomaces,’ ‘ Annals of Nat. Hist.,’
sec. ser., vol. i, p. 161, t. xi, xii, (1848.) The reproductive cell is formed either
between the halves of an isolated cell, separating from them in the sub-
sequent development, (Cyclotella, t. xi, f.D,) or between the halves of a cell
which is a link of a filament, sometimes parallel and becoming developed in
connection with the old filament, (Melosira, t. xi, f. a, c, aud Orthrosira,
t. xii, f. B,) sometimes pushing aside the halves of the mother-cell by
secretion of gelatinous matter, and developing at right angles to the old
filament, (Aulocosire, t. xi, f. B.) i

300 THE PHENOMENON OF

tion of the Diatomacex, and in itself presents nothing
impossible. The transition from a still incomplete
division to conjugation, is quite as conceivable as the
advance from a first incomplete division to a second,
such as we have become acquainted with in the quar-
tering of cells (p. 254). I will mention one more case
here, which can scarcely be explained otherwise than as a
reunion of two cells which have begun to divide, namely,
the not very rare abnormal occurrence of division of
individuals into three parts by two constrictions, in
. Euastrum and allied Desmidiacee. Nägeli has figured
such a specimen of Zuastrum (Cosmarium) Meneghinit,
Bréb.* The formation of the spores of Spirogyra
mirabilist might be caused by a process similar to that
in Melosira, if that species really, as Hassall states, forms
spores in all the cells of filaments which do not enter
into conjugation with others; this would be the more
conceivable in Spirogyra, since the external division of the
cells is preceded in this genus by the division of a
nucleus, and since the division is gradual.

Lastly, the supposed conjugation of the contents of
two adjacent cells in the formation of the spores of
Gdogonium, and of Bulbochete, with which it has a very
peculiar relationship, deserves an explanation. Decaisnet
and Hassall§ have noticed the strange circumstance,
that in the said two genera, the cell which immediately
precedes the swollen mother-cell of the spore, has little
or no green contents. Hassall thinks we may deduce
from this a passage of the contents of the lower cell into
the upper, aud hence compares the process of spore-
formation of @idogonium with that of the Spirogyre of
the section Rhynchonema, with the distinction, however,

* Nageli, ‘Hinz. Algen.’ t. vii, f. 7, 6, (as E. erenulatum, Ehrenb. ?)

T Zygnema mirabile, Hassall, 1. c., p. 156, t. 35.

+ ‘Essai sur une Classification des Algues,’ (1842,) p. 39. The figure
given at t. 14, f. 5, belongs to Bulbochete spherocarpa, A. Br., (setigera,
Auct., ex. p.

§ L.c., pp. 180—194, t. 50—53, (Gdogonium ; t. 54, (Bulbochcte.)

REJUVENESCENCE IN NATURE. 301

that the contents of the one cell do not make their way
into the next cell by a lateral connecting canal, as in the
said Spirogyra, but probably through an opening in the
partition separating the two cells. Leon le Clerc* has
already correctly objected to the idea of such a conjuga-
tion of the contents of the two adjacent cells, in the
(@Edogonia, that we not unfrequently find the lower as
well as the upper neighbour-cell of the sporiferous cell
filled with unattenuated green contents, and that some-
times two, and even three and four cells containing
spores follow in immediate succession. These statements
are perfectly accurate, and Hassall’s endeavours, partly to
set them aside, partly to turn them so that they shall not
oppose his theory, are unsuccessful. In the first place,
as regards the occurrence of several sporiferous cells in
succession, it must be remarked that two adjacent spore-
cells are met with more or less frequently in all species,
and I have often observed three to four in succession in
GEdogonium apophysatum and Landsboroughii.t If there
were only two, it might still be asserted that one had
attracted the contents of the cell next below it, the other
the contents of the cell next above it, in order to form
the spore out of coupled contents; but when three or
four sporiferous cells follow in succession, such a coupling
is no longer conceivable. In reference to the contents of
that cell which precedes a single, or several successive
spore mother-cells, it must be noticed of Gdogonium,
that these are certainly ordinarily, but not unvariably,
poorer in solid constituents, particularly in chlorophyll,
than those of other sterile cells, but at the same time are
never wholly devoid of colour or of granules, as, on the
contrary, is generally the case in Bulbochete. A similar,

* ‘Sur la Fructification du Genre Prolifera de Vaucher, ‘Mém. du
Muséum,’ iii, (1817,) p. 462. The old name of Proli a was founded on an
error, and was therefore changed to Gdogonium by Link

T @dogonium Landsboroughti, (Hassall,) is the species described and
figured, (t. 23, f.1,) by Le Clerc, as Prolifera rivularis. Le Clerc repre-
sents four adjacent sporiferous cells in @d. Rothii also, |. c., f. 8.

302 THE PHENOMENON OF

only less striking alternation, of more richly filled and
poorer, darker and lighter cells, occurs also in the sterile
or merely gonidium-bearing filaments of most of the
(Edogonia ; in those species, moreover, which have the for-
mation of microgonidia mentioned above,* the longer cell
which precedes every group of the short cells in which
the small swarmers are formed, is found poor im contents,
like the ante-cell of the mother-cell of the spore. None
of these phenomena can be explained by a subsequent
wandering of the cell-contents, produced by union of
previously separate cells, but are all caused by the distri-
bution of the contents in the very formation of the cells.
For in (Zdogonium occur secondary processes of cell-
formation in the filaments, possessing the peculiarity
that the individual cells of the filament divide, not into
like, but more or less strikingly unlike cells, and in such
a way that the upper of the two cells produced by divi-
sion is the shorter and richer in contents, the lower the
longer and poorer in contents. The difference of the
two sister-cells is slighter in filaments or fragments of
filaments remaining sterile, as also in those in which
merely macrogonidia are to be formed, and it is mostly
very striking, on the other hand, where the formation of
spores (or microgonidia) is to take place. The anterior
shorter cell, filled with more concentrated contents,
becomes, in this case, the mother-cell of the spore. This
process of cell-formation, division into unlike halves, is
frequently repeated in the lower cell, this again dividing
into a shorter, fuller, upper, and a longer, lower cell, &c.
Thus, in sporiferous filaments, a second, third, and fourth
spore mother-cell may be added successively to the first.
The same is exhibited in the formation of microgonidia,
wherein I have seen the number of short mother-cells of

* Gdogonium echinospermum and apophysatum. See p.141. The nu-
merous, closely superstratified little cells, which Le Clerc, 1. c., f. 9, figures
between the larger cells, in a filament supposed to belong to Prolifera
rivularis, (Gdogon. Landsboroughii,) and in the explanation of the plate
takes for spiral-filaments, are doubtless emptied mother-cells of microgonidia.
(See Thuret.)

REJUVENESCENCE IN NATURE. 303

microgonidia, added on to one another in this way,
amount to six or seven, which indicates a five- to six-fold
repetition of the division in the descending order. ‘he
formation of the globular or ellipsoidal expanding mother-
cell of the spore of Bulbochete is peculiar, and deviates
somewhat from the similar process in (Zdogonium. The
spore-bearing cell (the sporangium) usually presents itself
in this genus as a branch at the upper margin of a stem-
cell, and mostly as the first (more rarely the second) cell
of the branch, surmounted by a small bristle-bearing cell,
or even by two cells, one narrowly tubular, and filled
sparingly with green contents, on which the second,
hyaline and bristle-bearing, is seated like a little lid. The
origin of the branch becoming developed into a sporan-
gium, takes place, as in Cladophora, through formation
of a bagging out process at the upper margin of the stem-
cell. Into this protruded sac the densely-fluid, green con-
tents of the stem-cell (containing starch-granules) gradu-
ally travel, and this in two portions. In the first place
merely the lower half of the stem-cell loses its coloured
contents, and then it is shut off from the upper, still
green half, by a delicate horizontal partition ; soon, how-
ever, since the protruded sac, not yet shut off from the
stem-cell, continues to grow and to expand toward a
globular form, the green contents travel out of the upper
half of the stem-cell, into the sac-like branch, after which
the partition is formed between this and the stem-cell.
The stem-cell bearing the sporangium often appears per-
fectly hyaline after this process, and always divided in
the middle by a horizontal septum, a division which
never occurs in the other stem-cells. Only as an excep-
tion have I seen stem-cells more or less densely filled
with green contents, notwithstanding that they bore a
sporangium at the upper margin; the division of the
cell did not exist in this case. The formation of the one
to two little cells beside the bristle, at the tip of the
sporangium, does not take place until after the protruded
sac is shut off from the stem-cell. From this sketch of

304 REJUVENESCENCE IN NATURE.

the process it will be clear, that in Zulbochete, as in
(edogonium, a concentration of the formative contents, at
the cost of the sterile sister-cell, is connected with the
production of the cell destined to form a spore, but that
there is not any union of the contents of two previously
separate cells. These cases, therefore, are allied, not so
much to the phenomena of conjugation, as to the pheno-
mena of division into cells of unequal power and of
different destination, mentioned under B* (p. 250).

305

CONCLUDING REFLECTIONS.

Tuvs have we completed our design of subjecting to
minute inspection, in the example of the development of
the Vegetable Organism, the phenomenon of Rejuve-
nescence, a phenomenon profoundly connected with the
essence of natural life, and lying at the base of all
progressive movement of life and development, with its
multifariously complicated ascending and descending
vibrations, in the largest as in the smallest circle of
Nature, since this movement is sustained in every
case only by renovation. We have examined it in the
Formation of Sprouts, by which the individual vegetable
stock is expanded into the trunk of a family, which, in
essential or inessential combination, distributes the
individual functions amongst its members; we have
traced it in the sprout itself, in the formation of its
graduated and articulated interlinked structure, in the
great tide of the graduated metamorphosis, as in the
individual waves of this, the Leaves; finally, we have
recognized again in the smallest sphere of formation, in
which the vegetable strives to establish its everywhere
only imperfectly attained individuality, in Cell-formation,
with which every cycle of development commences, and
by the divided or undivided, homogeneous or hetero-
geneous, combined or free renovation of which, the
plant carries to fulfilment the multiplicity of structure of
all its organs, and indeed lays the foundation for the

vital continuation of the species beyond the limit of the
20

306 THE PHENOMENON OF

old structure, in renewed construction of the organism.
The examination of Cell-formation leads back, therefore,
in all the wider circles of Rejuvenescence, into the plastic
life of the plant, nay, it leads us even beyond the circle of
the individual development and the related close family
union in the sprouting vegetable stock, to the true
reproduction of plants, which presents itself, in con-
nection with the less perfect renovations of Cell-formation
in the preceding circles of development, as the most
decided and freest reconstruction of the cell, and at the
same time as the recommencement dating itself furthest
back, the most complete Rejuvenescence. As in the
formation of the individual, each new stage arises with
a new section of Cell-formation, so also does the transi-
tion of one individual developmental process to another ;
and thereby the intercalation of the individual life in the
compound life of the species, in every case, takes place
through a new impulse in the cell-formation. Con-
sequently Cell-formation is not merely the commencement
of, and the means to, the production of subordinate
tissues ; it is, at the same time, through the law of alter-
nation of generations, subordination and serial arrange-
ment, prevailing in its progressive renovation, the com-
mencement of every comprehensive complication in the
organism of the plant, of the single organ as of the
special stage in the series of organs, of the single lines of
development or the subordinate axes of the vegetable
stock, as of the individuals becöming developed into
separate stocks. Thus the consideration of the Cell-
formation in the Rejuvenescence of the Individual is most
intimately connected with that of the Rejuvenescence of the
Species ; indeed so intimately that the boundary between
the two is often difficult to draw, as we have seen in the
foregoing pages, at the lowest stage of the Vegetable

ingdom, in a portion of what are termed Unicellular
plants, plants with generations of vegetative cells separ-
ating from each other (p. 125, &c.) And, just as we see
here, at the lowest stage, the cell-division (p. 233) else-

REJUVENESCENCE IN NATURE. 307

where belonging to the development of the combined
organism, appearing as a mode of reproduction, so also
in the higher groups of the Vegetable Kingdom, we see
Sprout-formation extricated in most varied ways from the
subordinate relation to the “whole” of the vegetable
stock, and serving for the formation of independent indi-
viduals.*

The interweaving of the reproduction and the indi-
vidual development is exhibited in a very strange manner
in that division of the Vegetable Kingdom in which a
decided contrast of sexes first appears,f namely, plants of
the Moss and Fern kind, in which the fertilization,—
which we have been used, from its mode of occurrence in
the whole realm of the Phanerogamia, as well as in the -
Animal Kingdom, to imagine connected with the origin of
new individuals,—does not coincide with the commence-
ment of the individual cycle of development, but on the
contrary falls in the middle of this, becoming the means
of transition from a lower to a higher stage of the meta-
morphosis. In both cases it is a single cell in which the
subsequent development is called forth through the influ-
ence of the male sex, but in one case it is the primary
cell of the entire generative cycle, 7. e. of all the cells
which, by their connected succession, represent the indi-
vidual ; in the other case it is a cell occurring within the
cycle itself, and merely forming the beginning of a new
segment of it. In the Phanerogamia itis the germ-cell,{
formed, after the entire accomplishment of the meta-
morphosis, in the uppermost central cell of the seed-
sprout, (the enibryo-sac of the ovule,) which receives the
impregnation by means of the advance of the pollen-
tube up to the embryo-sac ; with it the entire individual

* Reproduction by propagula, (in the Mosses and Liverworts,) by
bulbels, runners, tubers, &e., see p. 40.

+ (This expression, as well as various other references of the same nature,
must be checked by comparison with subsequent researches. Thuret,
Nägeli, Itzigsohn, Tulasne, Berkeley, and Broome, have pointed out con-
ditions indicating that sexuality is universal.—A. H.)

£ See p. 276.

308 THE PHENOMENON OF

development recommences. In the Mosses and Ferns it
is the central cell ofthe archegonium,* (a sproutlet which
may be compared with the nucleus of the ovule,) which
is impregnated, in a manner not yet accurately known,
through the spermatozoids formed in the antheridia ;
the development of this, however, is not a recom-
mencement of the entire cycle, but only an advance to a
new and higher stage of the metamorphosis, which,
unfolding in connection with the pre-existing preparatory
structure, carries over the individual life only after more
or less complex intermediate stages of formation, to the
production of the true reproductive cells (spores), with
which, and without further impregnation, the new cycle
of development commences. The point of transition
marked by the occurrence of impregnation, is, again,
different in the Ferns and Mosses. In the Mosses, the
transition from the Algoid prothallium to the leaf-forming
stem takes place before the impregnation, which causes
only the development of the spore-forming capsule; in
the Ferns, an the contrary, the preparatory structure
does not go beyond the leafless prothallium, and the
advance to the leaf-forming stem depends upon the im-
pregnation. This mode of viewing the case, very strange
as the introduction of the impregnation into the midst of
the cycle of the individual development may be, appears
to me more in accordance with nature, to interrupt less
the natural connection, and to correspond better with the
graduated course of the metamorphosis, than that given
by the discoverer of the archegonia of the Ferns,+
according to which the thalloid product of germination of
the spore of the Ferns is compared, as the bearer of the
impregnation organs, to the flower of the Phanerogamia,
while the spore from which it is developed is termed a

* See Gottsche, on the “Fructification of the Jungermanniz geocalycex,’
“Nov. Act.,’ xxi, ü, 445, t. 30, f. 8. The bicellular condition of the endo-
gonium of Calypogeia Trichomanes there represented is certainly preceded by
a unicellular stage. i

+ Leszezye-Suminski, ‘Zur Entwickl. der Farrnkrauter,’ Berlin, 1848.

REJUVENESCENCE IN NATURE. 309

flower-bud detached from the mother-plant. On such a
theory, the new individual cycle of development would
not begin with the spore, but with the central cell at the
base of the archegonium.* Applying this view to the
Moss, the first (lowest) stage in the cycle of its indi-
vidual life would be the formation of the sporangium,
the second stage that of the confervoid prothallium, the
third that of the leafy stem, which would finally bear, as
the term of the development, the impregnation-organs,
antheridia and archegonia. ‘The more minute investi-
gation of the still imperfectly ascertained processes of
impregnation in the Rhizocarpes and Lycopodiacez, as
also those of the Gymnosperms, (Cycadeze and Coniferz,)
aberrant among the Phanerogamia, and perhaps having
an affinity to the higher Cryptogamia, - will certainly
enable us to place the strange conditions in the repro-
duction of the Mosses and Ferns in clearer connection
with the reproduction of the Phanerogamia, while the
investigation of the Characex and Floridez promises a
new point of attachment for the lower department of the
Cryptogamia.t+

‘That an actual impregnation does occur in the Mosses
and Ferns is indicated not merely by the well-known
experience of bryologists on the dependence of the fructi-
fication of dicecious Mosses on the social growth of the
two sexes,} but also the occurrence of hybrids, which
were known in the Ferns even before the discovery of the

* According to Suminski’s here certainly incorrect representation, the
embryo of the new individual is formed in the central cell of the archegonium,
through the penetration of the tail of a spermatozoid into it.

+ (The above was printed in 1850; the speculation then put forth has been
realized to an extent scarcely to have been expected so soon; the researches
of Mettenius, Nageli, and above all Hofmeister, have carried on this subject
almost to completion in its main features in the higher Cryptogamia; the
lower Cryptogamia, (Thallophytes,) still require extensive investigation. For
the facts, as also the literature, see the ‘ Report on the Reproduction of the
Higher Cryptogamia,’ by the present translator, in the ‘Annals of Nat.
Hist., 2 ser., vol. ix, p. 441.—A. H.)

+ See Schimper, “Recherch. sur les Mousses,’ p. 55.

310 THE PHENOMENON OF

impregnation organs,* and have lately been observed in
the Mosses.+ I mention this occurrence of hybrids
among the Ferns and Mosses, in order to adjoin some
remarks leading us back to our subject. If hybrids are
formed in Mosses and Ferns, this takes place in a pre-
paratory structure which belongs to the mother-plant ;
the individual entering into the state of hybridation,
(according to the ordinary acceptation of the term,)
becomes composed, consequently, of one part which is
mother-plant, and one part which is hybrid. The hybrid
must develope, as it were, grafted on the mother-plant.
Not until the second generation, that developed from the
spores of the hybrid, can the preparatory structure
assume the hybrid nature, and this, according to the
analogy of most Phanerogamous hybrids, might be sterile
by itself, and only in case of impregnation from one or
other parent species, develope to an ulterior structure
recurring more or less to this. The prothallia of the

* The discovery of the antheridia of the Ferns was made by Nageli in the
year 1842, and published in 1844, (‘Zeitschr. fur Wiss. Bot.,’ heft 1,
p- 168 ;) the above-mentioned treatise of Suminski, in which the archegonia
were first described, dates from 1848; the first observation of a hybrid fern
was published by Martens, in ‘ Bulletin de Acad. Roy.’ de Bruxelles, 1837.
The hybrid there mentioned of Gymnogramma (Ceropteris) chrysophylla and
calomelana, subsequently named G. Martensii, was soon followed by a second
between @. chrysophylla and distans, (G. Massoni, Auct.,) described by
Bernhardi in Otto and Dietrich’s ‘ Gartenzeitung,’ 1840, p. 249; Regel has
enumerated several more hybrids from the same genus in the 32d No. of the
‘Botanische Zeitung,’ for 1843. I myself found, in the year 1834, in a
mountain valley near Baden, among dspidium Filiz mas, and A. spinulosum,
(the normal form together with the variety dilatata,) several rhizomes, all
within a small space, of a fern which stood about mid-way between the
two species named, and probably was to be regarded as a hybrid product of
them. I called it Aspidium remotum, and formerly regarded it, doubtfully,
as a variety of A. rigidum, which it resembled, not only in habit, but in
degree of formation and mode of decrease of the pinnew. I have never
since been able to find it again, either in the original station or anywhere
else in the Black Forest, but it has maintained its existence in the Botanic
Garden of Carlsruhe, whence it has passed into the gardens of Freiburg and
Leipsic. See Doll, ‘Rhein. Flora,’ p. 16.

T See Bayrhoffer, ‘Uebersicht der Moose, Lebermoose und Flechten des
Taunus,’ (‘Jahrbuch. des Vereins f. Naturkunde im Herzogth. Nassau,’
5 heft, 1849,) where two supposed hybrids are mentioned, namely, 1, of
Physcomitrium fasciculare, and 2, of Physcomitrium pyriforme, with Funaria
hygrometrica.

REJUVENESCENCE IN NATURE. 311

Ferns are so alike, and at the same time so transient, that
it would scarcely be possible to institute profitable obser-
vations ; so much the more is investigation of the hybrids
of the Mosses, which, when once attention is directed to
them, will certainly be found in greater numbers, to be
recommended to bryologists. The two hybrid Mosses
observed by Bayrhoffer, seem, from his account, actually
to have possessed the characters of the mother-plants,
(Physcomitrium fasciculare and pyriforme,) in respect to
the vegetative organs, while the fruit is stated to have
exhibited, especially in the structure of the peristome, a
distinct approximation to the character of the supposed
father, Funaria hygrometrica. From the occurrence of
numerous archegonia upon one and the same moss-plant,
we might expect even to find, when the hybrid impreg-
nation only affected particular of them while others
were fertilized by the proper species, two kinds of fruit
perfected on the same “stock,” normal and hybrid fruits.

Supposing these views to be actually true of the
hybrids of the Mosses and Ferns, it might afford us a
further confirmation of the hypothesis, that the indi-
vidual cycle of development of these plants does not begin
with the spore, but with the central cell of the arche-
gonium, which is called into life by impregnation. If,
on the other hand, we keep to the old conception of the
commencement of the individual with the spore, these
strange processes will appear merely as a further proof
of the intimate connection and interlacement of the indi-
vidual development and reproduction,in which respect they
are of especial interest here, particularly when we place
them in relation with the cases already mentioned,* which
indicate the possibility of the occurrence of aberrations
ordinarily connected with the reproduction, in the midst
of the individual development, (in the wider or narrower
sense !) in the higher divisions of the Vegetable Kingdom.

It is well-known that those very varieties of plants -
which are most important and interesting, those in which

* See page 24.

312 THE PHENOMENON OF

the most considerable deviations from the normal character
of species occur, are not produced on the individual stock,
to whatever influences of nature and art this may be
exposed, but are connected with the reproduction in their
origin, since they grow up, as it were accidentally, from
seeds. Among these are many varieties very striking in
reference to the degree of division of the leaves, e. g.
simple-leaved forms of plants which, in the parent-form,
have ternate or pinnate leaves (Fragarta vesca mono-
phylla,* Fravinus excelsior simplicifolia),t and vice versd,
divided-leaved modifications of plants, with normally un-
divided leaves or leaflets (Alnus glutinosa laciniosa, Betula
alba laciniata v. dalecarlica),+ Corylus Avellana laciniata,
Cytisus Laburnum quercifolus, Vitis vinifera laciniosa;§
also unarmed varieties of normally spinous plants (Robinia
Pseudoacacia inermis) ;|\ varieties in reference to the colour
of the leaves (Fagus sylvatica sanguinea,] Corylus tubulosa

* Raised by Duchesne, in the year 1761, from seeds of the common
Fragaria vesca, and usually returning, when the seeds are sown, to the
parent-form with ternate leaves. Duchesne, ‘ Hist, des Fraisiers, p. 124;
Godron, ‘ De l’Espéce et des Races,’ p. 36.

+ Fr. simplicifolia, W., (heterophylla, Vahl.) In De Candolle’s ‘ Pro-
dromus,’ (viii, p. 276,) it is mentioned as a peculiar species, occurring in
England and Ireland, while Sprengel, (‘Syst. Veget.,’ i, 97,) places its
nativity in North America! De Candolle, to establish the specific distinc-
tion, gives, in addition to the form of the leaf, certain characters derived
from the size and form of the fruit, which, however, I am compelled to regard
as au unimportant individuality of De Candolle’s specimens, since the trees
of the simple-leaved ash, cultivated in the Botanic Garden of Carlsruhe,
agree exactly with the common ash, (F. excelsior,) in their fruit. Persoon,
in reference to the origin of this variety, says expressly, (‘Syn.,’ ii, 604,)
“e seminibus Fraxini elatioris vulgaris ortam vidi.” Spenner found, on the
Schienberg, near Freiburg, a completely analogous variety of Rubus Ideus,
with leaves resembling those of R. arcticus.

{ Both occur, probably only isolated, in Sweden and Lapland. In
gardens they are increased by cuttings, and when sown probably recur to the
entire-leaved parent forms. The other examples named are known only as
garden-plants.

§ The parsley-vine, as it is called. See Babo and Metzger, ‘Wein u.
Tafeltrauben,’ p. 33, h. ii, 10.

|| A single specimen of this was obtained by Descemet from a sowing in
1803, and it is now generally diffused. Its seeds furnish the spiny parent-
form again. (See Chevreul, ‘Considérations gén. sur les Variations,’ &e.
‘Ann. des Sc. nat.,’ 3me sér., vi, 157, 1846; Trans. in ‘Journ. Hort.
Society,’ vol. vi, p. 61, 1851.)

@ ‘The copper-beech universally diffused in gardens is derived from

REJUVENESCENCE IN NATURE. 313

atropurpurea), colour and doubling of the flower (Zudipa,
Dianthus, Primula, Dahlia, &c.); as also, finally, the
numerous varieties, chiefly marked by the condition of
the fruit, which we have among our cultivated orchard
and other fruits. The origin of the varieties mentioned
here does not depend so much upon an alteration
gradually insinuating itself into the external conditions
of existence, as upon a development, under favorable
conditions, of the multiformity possible within the limits
of a certain type, which is implied especially in the fact
that very different varieties may arise from one and the
same sowing, even from the seeds of one and the same
fruit, and this without influence of impregnation from a
foreign source, and under equal external circumstances.*
The development of this multiplicity takes place ordinarily,
as stated, by means of reproduction, and it may disap-
pear in the same process ; the new varieties grow up from
seed, and may in like manner return to the parent-form
by sowing. But sometimes a similar production and a
similar retrogression of the variety takes place by means

forest near Sondershausen, in Thuringia; it is propagated by cuttings,
since when sown it mostly returns to the common green beech. See
Bechstein, ‘ Forstbot.,’ f. 1, p. 229. Ibid., (267,) mention is made of a
copper oak, (Quercus pedunculata sanguinea,) of which a single tree is said
to exist in the Lauchner Forest, near Gotha.

* According to Van Mons, this sometimes goes so far that a peculiar
variety springs from each single seed, e. g., from the ten seeds of a pear,
were developed an equal number of new sorts of pear. Cultivation of course
has an influence upon the production of new varieties, yet not on the indi-
viduals directly exposed to its effects, but on their progeny. In most cases it
is impossible to demonstrate a definite relation of the influence of cultivation
upon the qualities of the varieties thence arising; it appears rather, on the
whole, as if the unusual conditions, favorable to a luxuriaut state of develop-
ment, afforded by cultivation, awakened in the plant the inward impulse to
the display of all those variations possible within the more or less narrowly
circumscribed limits of the species. According to the experience of gar-
deners, in particular of the celebrated Belgian orchard-fruit grower, Van
Mons, this impulse is only gradually awakened in the wild plant subjected
to cultivation, often requiring several generations, until it has attained its
maximum and is finally extinguished in the formation of constant varieties.
At the same time, the fact of experience is remarkable, that improved
varieties propagated by cuttings acquire so much the more inclination to
return to the parent form the longer they are propagated in this way. (See
Godron, ‘De Espéce et des Races,’ p. 83, where also are enumerated the
treatises of Van Mons not within my reach here.)

314 THE PHENOMENON OF

of mere vegetative development, so that even the indi-
vidual vegetative “stock” may comprehend several
varieties within its limits at successive points in time, or
at collateral points of space. Here refer many well-
known facts, as, for example, that the wild Hepatica
(H. nobilis) with its lovely blue six-leaved flowers, if
transplanted from the shady mountain-groves into a
garden, usually produces, even in the next year, double
and in addition mostly red flowers; in like manner that
the Periwinkle (Vinca minor) often acquires white or
brownish-violet flowers in place of its blue ones, in
gardens. If we sum up mentally the successive annual
products, such stocks striking into variety appear com-
posed of two modifications of the species; the Hepatica,
for instance, the annual Rejuvenescence of which is
effected by direct continuation of the main axis,* looked
at in this way, represents a stem bearing simple blue
flowers at its lower parts, and double red ones above.
But that which we only see here by the mental combina-
tion of what is separate in time, meets us in actually
united in other cases, in which the formation or retro-
gression of the variety only occurs on particular sprouts
of a branched stock, or in which several of the modifica-
tions in which the species may appear, present themselves
so distributed on different parts of one and the same
stock, that it is impossible to determine to which modifi-
cation the stock originally belonged. Cases of both
kinds are known in Vines and Currants, which bear two
kinds of bunches of fruit,f of Melons with two kinds of
fruit,t of Rose ‘stocks’ which bear two kinds of
flower,$ &c. I have observed cases of the first kind in

* Seep. 54.

f See Metzger, ‘ Landw. Pflanzenk.,’ ii, 913 and 917, where it is stated
of the red Zraminer that it often brings forth white bunches when old, and
of Alavner, (Burgundy,) that it not unfrequently bears blue and red bunches
on the same “stock ;” I have often seen isolated red-berried bunches on
“stocks” of Kibes rubrum with white berries.

t Sce Sageret, ‘Ann. des Sc. nat.,’ t. viii, 309, (1826.)

§ On the variety of Rosa Eglanteria, with flame-red flowers, (R. bicolor,

REJUVENESCENCE IN NATURE. 315

the Laburnum with incised leaflets (Oytisus Laburnum
quercifolius), as also in the more or less incised variety of
the Beech (Fagus sylvatica asplenifolia) in the Carlsruhe
Botanic Garden, the ordinary parent-form reappearing
with the perfectly marked variety, on isolated sprouts of
these plants. The same phenomenon has also been
observed in the Parsley Vine.* The strangest cases
belonging here are not those in which the modifications
are combined with the sprouts, as subordinate individuals
of the “stock,” but those where the process of separation
of the varieties extends only to some limited part of the
organs, or even to single groups of cells, and perhaps
even to the individual cell, as exhibited by the pheno-
menon so frequently occurring among cultivated plants,
of plants with variegated leaves (e. 9. in Cabbages,t)
divided irregularly into several colours, striped or dap-
pled flowers (in Tulips, Pinks, Roses)t and fruits (in
Gourds, Apples, Grapes, &c.)§ One of the most beau-
tiful examples of this kind is offered by Mirabilis
Jalappa. The three varieties, with deep-red, nankin-
yellow, and white flowers, are not unfrequently found
two or even all three united on the same “ individual,”
in such a manner that there are stocks with the
flowers striped with: 1. red and yellow, 2. red and
white, 3. yellow and white, and 4. red, yellow, and
white; and not unfrequently, also, isolated single-coloured
flowers present themselves on the same stock, these being

Jacq.) I have often seen isolated shoots bearing pure sulphur-yellow
ee (R. lutea, Mill.,) sometimes even flowers divided into the two
colours.

* See Babo and Metzger, 1. c., p. 35, where the authors state that they
have detected, on vigorous stocks of this variety, isolated branches with
leaves which were merely five-parted and undistinguishable from the leaves
of the white Guledel.

+ Here belongs what is called the federkohl, a variegated winter cabbage
(Brassica oleracea acephala,) which represents a mixture of the green and red
cabbages, (Metzger, ‘ Kohlarten,’ 20.)

{ The striped rose, frequent in gardens, is a Rosa gallica, with white, red-
striped flowers, on which sometimes occur half or even entirely red flowers.

§ Thus in the two-coloured Morillon, (Morillon panaché.) See Babo and
Metzger, ‘ Wein. and Tafeltrauben,’ 169, heft. ix, t. 4.

316 TUR PHENOMENON OF

of three kinds, red, yellow, and white, in the fourth
case.

Analogous cases of heterogeneous composition of the
vegetable stock occur in Aybrids of Phanerogamous plants,
through return to the parent form on the hybrid stock
itself, whereby it may happen that two specifically dif-
ferent species may present themselves united, together
with the hybrid, upon the same stock. This, however,
is a far rarer phenomenon than the occurrence of several
varieties on the stock, for hybrids, as the celebrated
experiments of Kélreuter* showed, ordinarily return by
way of reproduction, to one or other parent species, after
having been impregnated by this for several generations.
The only certainly known instance of the recurrence of a
hybrid plant to the parent species on the stock itself, has
been found recently in the generally diffused garden
intermediate species, between Cytisus Laburnum and
C. purpureus (C. Laburno-purpureus, Walpers,t C. Adami,
Poiret),{ the hybrid nature of which, in spite of the con-
trary assertions of Loudon$ and Reissek, | cannot well be

* See his preliminary reports (‘ Vorlaufige Nachrichten) of experiments
relating to the sexes of plants, particularly the third series, (1766,) p. 51,
where is described the ‘complete conversion of one natural species of plant
into another,’ namely Nicotiana rustica into N. paniculata. The first
impregnation of N. rustica with N. paniculata produced a hybrid, which
assumed completely the character of the parent plant in the “ fourth
ascending step,” 3. e., after three transitional generations produced by
repeated impregnation with N. paniculata.

Nicotiana RUSTICA Q
paniculata & ¢ 22
paniculata é$Q
paniculata é
pened N. PANICULATA
paniculata ; x

T ‘Repertorium,’ i, 634, (1842,) where two figures of it are cited. (The
‘ Botanist,’ i, t. 7. “Bot. Register,’ t. 1965.) i

1 The authorship of the name C. Adami is thus stated everywhere;
pasts Poiret has given a notice or description of Adam’s new plant, I do not

now.

$ According to Loudon, (as appears from a note in the ‘ Bot. Zeitung,’
1843, p. 133,) Adam obtained his new Cydisws by grafting a bud of C.
purpureus on C. alpinus (?). I cannot consult the source of the statement
here cited, (‘Gard. Mag.,’ xii, 225, and xv, 122.)

|| According to Reissek, (Haidinger, ‘Berichte über die Mittheil. von

2?
A

REJUVENESCENCE IN NATURE. 317

doubted, since the French authors* unanimously assert
it, and this assertion finds strong support in the sterility
of C. Adami, observed by Hénon and Seringe, and con-
firmed by the behaviour of the specimens in the Carlsruhe
and Freiburg Gardens. CO. Adami bears its name after
the nurseryman Adam, of Vitry, near Paris, who raised
it in the year 1826. The mother-plant is said to be
C. Laburnum, the father C. purpureus.t In its arbo-
rescent growth and many-flowered racemes it far more
resembles the common Laburnum, than the low shrubby
C. purpureus with its two-flowered inflorescences hidden
between the leaves; but the racemes are shorter and not
so full of flowers. The dirty red colour of the blossom,
the smoothness of the leaves, calyx, and germens, which
are villous in C. Zaburnum, remind us more again of
C. purpureus. During the last ten or twelve years it
has been observed in most diverse places (thus in Lyons,

Freunden der Natur in Wien,’ i, p. 12, extracted in the ‘Flora,’ 1846,
p- 623, and 1848, p. 26, in Hornschuch’s essay on the ‘sporting’ of plants,
with which extract alone I am acquainted,) a shrub of Cytisus Laburnum, in
the Vienna Botanic Garden, which had previously always borne only the
yellow blossom proper to this species, suddenly produced, in the spring of
1846, on some of its branches, the red flowers of ©. Adami, and here and
there red and yellow flowers mingled in the same racemes ; nay, a twig per-
fectly representing C. purpureus is said to have sprung from a yellow-flowering
branch of this shrub. Hornschuch found, in the occurrence thus narrated by
Reissek, an analogue of the many other remarkable stories of transformation
which he ee from old and recent sources, (for example, the growth of
a Lolium branch from a wheat stock, the occurrence of isolated oat spikelets
on wheat spikes, the transformation of oats into rye by a particular mode of
treatment, &c.,) and a striking proof of the possibility of conversion of one
species of plant into another. Without entering generally into the con-
tested question, the present case admits of a simple, and I think not very
hazardous explanation, in the assumption that an unknown hand had
engrafted scions of C. Adami in the said shrub of C. Laburnum, that at the
time of the observation there existed recurrences of the C. Adami to
C. Laburnum, and that the shoot of C. purpureus mentioned grew out of
such a graft, (certainly not out of a Laburnum branch.)

* Heénon (and Seringe,) ‘Aun. des Sc. phys. et nat. de la Soc. d’Agricult.
de Lyon,’ ii, 375, (1839.)—Buchinger, ‘ Flora,’ 1842, i, 378.—Kirschleger,
‘Institut.,’ 1843, p. 372, and ‘ Essai de Tératol. Vég.,’ 71, (1845.)—Chevreul,
‘Ann. des Sc. nat.,’ 2 sér., vi, 186, (1846.) i

+ Kirschleger, 1. c.

318 THE PHENOMENON OF

Strasburg, Schiltigheim, Munich, Vienna, Carlsruhe,
Freiburg (and England), that single shoots present them-
selves upon the stocks of C. Adami, which (without any
mediating transitions)* represent quite purely the yellow-
flowered and villous C. Zaburnum, or, what is much more
striking from the great difference of the habit, branches
perfectly characterised as C. purpureus. Ordinarily only
one or other of the two parent species appear in this
way,t but sometimes both on the same stock.{ The
formation of sprouts, and indeed the formation of twig-
buds, is consequently the turning point here, with which
the recurrence of the hybrid into the parent-species
occurs; the recurring buds develope into stronger or
weaker twigs, which in all parts belong entirely to one
or other parent-species (stem-, leaf-, flower-, and fruit-
formation). Sometimes, however, the case occurs of the
recurrence to the parent-species first in the small twigs
of the inflorescence, 7. e. in the transition to the single
lateral buds of the raceme, whereby the flowers belonging
to the parent-species originate in the inflorescence of the
hybrids and miwed racemes are formed. ‘Three kinds of
these are possible, namely: 1, C. Adami mixed with

* Kirchleger says, indeed,—“ J’ai pu méme, en 1844, observer toutes les
transitions de ces trois sortes de branches (avec leurs inflorescences et leurs
fleurs) les unes aux autres,” but this assertion is certainly incorrect.
Kirschleger was certainly deceived by the mixed inflorescences and flowers,
which I shall describe more minutely.

f Ihave observed this in Carlsruhe and Freiburg, where I never saw
both parent species produced out of the same stock. “Buchinger found the
same. I mention this circumstance expressly in order to remark that the
explanation given by Chevreul, (I. c.) by which the recurrence of C. Adami
to its parent species as a decomposition of the hybrid into its two portions
(somewhat as in a chemical decomposition) is inapt.

4 This is expressly asserted of the tree occurring in the garden of Prof.
Schweighauser, at Schiltigheim, which was described by Kirschleger. (This
occurred also in the specimen in the garden of L.W. Dillwyn, Esq., of Swan-
sea, where the shoots eam the blossoms of the parent species were fertile,
ripening seed, while the hybrid blossoms were sterile as usual.—A. H.)
Since it is probable that all the specimens of C. Adami diffused in gardens
are cuttings of a single mother-stock, the distinction, whether only one or
both parent-species present themselves, becomes of less importance.

REJUVENESCENCE IN NATURE. 319

flowers of C. Laburnum ; 2, C. Adami mixed with flowers
of C. purpureus ; 3, C. Adami mixed with flowers of both
parent-species. Hitherto I have only observed the first
of these three cases, to which also belong the mixed
racemes described at Hénon, the isolated yellow flowers
(belonging toC. Zaburnum) being displayed among the ordi-
nary rose-red flowers of C. Adami.* These mixed racemes,
at the same time, exhibit the peculiarity that the yellow
flowers set fruit, while the rose-red fall off immediately
after the flowering, so that in the recurrence of C. Adami
to one or other parent-species, the fertility lost in the
hybrid reappears. But the strangest thing that happens
in the recurrence of C. Adami to C. Laburnum, is the
phenomenon of mixed flowers, which belong, both in the
calyx and the corolla, partly to C. Adami, partly to
C. Laburnum, in which even single segments of the calyx
and single petals are halved, the former appearing
half reddish-brown and smooth (C. Adami), half grey-
green and villous, the latter half red (C. Adami) and
half yellow (C. Laburnum). A raceme in which this
occurred} exhibited, carefully counted up, among the
32 flowers it bore, 21 unaltered flowers of C. Adami,
3 pure flowers of C. Zaburnum, and 8 mixed flowers, the
7 of which, compared in the subjoined table,{ exhibited
the following conditions of intermixture in calyx and
corolla.

* In reference to the hybrid nature of C. Adami it is not unimportant to
remark that the reverse phenomenon, namely, racemes of C. Laburnum
intermixed with single flowers of C. Adami, has not been observed either by
others or by myself. If these mixed racemes depend on a partial recurrence
of the hybrid to the parent-species, this case cannot occur at all.

In the Carlsruhe Botanic Garden, May 1843.
Compare here the outlines in plate V and the accompanying explana-
tions. The eighth mixed flower was not in perfect preservation.

§ I neglected to examine accurately the condition of the stamens and
ovaries of these flowers.

320 THE PHENOMENON OF

No. of the Flower. | Sepal. | Petal. | Together.
Adami 42 g1 | 8
U | Laburnum i 14 2 } 2
nu, { Adami 4 4 8 } 10
* | Laburnum 1 1 9g
Adami 24 33 1/6
UN | Laburnum gh 1 4 } 10
Adami 23 3 54
I. | Laburnum gi | 9 4 } 10
Adami 23 2 44
Y- | Laburnum a4 | 3 51 } 10
Adami Ox 1 34
VI. 7 Laburnum gi 4 ‘a } 10
Adami 1 0 Io
VIL | Laburnum 4 5 9 }

It need scarcely be remarked, that these mixed flowers
appearing on Cyfisus Adami, are fully analogous to the
previously examined examples of mixed flowers (and
fruits) ; the only distinction is that there it was partial
sporting of one variety into the other, here a similar
reversion of the hybrid form into the mother-species.

We have devoted our attention to this entire series of
strange cases, in which the ordinary law of the invaria-
bility of the specific and individual character within the
vegetable stock appears to be suspended, because they
serve us as a proof of the intimate connection of the
course of development of the individual with the history
of the species. As the aberrations in the course of the
individual metamorphosis are especially fitted to afford us
an insight into its law,—since they reveal the internal
connection and the essential similarity of its foundation,
through unusual transitions, through anticipatory* or
retrogressivet interweaving, or finally by complete return

* Compare the frequent cases of a petaloid uppermost euphyllary leaves
in Tulips, Caltha, Trollius, the petaloid calyx of the double Primroses, of
Rubus cesius with petaloid inner sepals, (Act. Nat. Cur., xv, i, t. 31, f. 2,)
of Sempervivum tectorum with stamens of the inner circle passing into
carpels, &e.

Rosa, Ranunculus, Adonis, with the outermost sepal passing into euphyl-
lary formation ; similarly Rosa and Linum with sepaloid first petal; the half
double flowers with partial conversion of the stamens into petals, &e.

REJUVENESCENCE IN NATURE. 321

of the formations to the starting point,*—so must the
last-examined deviations from the usual mode of transition
to new organic destinations, belonging ordinarily to the
cycle of development of the species, not of the individual,
point to the common characters, which connect the tran-
sition from individual to individual, with the transition
from one structure to another within the individual
organism of the plant.

In the Introduction we endeavoured to seize the points
common to these two domains, as the process of Bejuvenes-
cence, and the minute investigation of the phenomena of
Rejuvenescence in the course of life of plants, carried out
in the three main sections of our reflections, enable us now
the more readily to examine from the same point of view
the Rejuvenescences of the species through reproduction.
The transition to the new individual finds its analogue
within the species, in Cell-formation, as the freest modi-
fication of it, as we have seen especially in the formation
of the germ-cells (germinal vesicles) of the Phanerogamia ;
it finds its analogue, further, in Sprout-formation, here
again representing the most independent modification of
it ; for while the sprouts belonging to the cycle of deve-
lopment of the “stock” are unfolded, either in permanent
combination with the mother-stock, or if they separate
from it, are connected with it in the earliest period of
development, yet the embryo, as primary sprout of a new
vegetable “ stock,” is always free from its earliest forma-
tion. As in the various gradations of the interlinking
(Gliederung), which the vegetable stock acquires through
its Rejuvenescences in Cell-formation, Leaf-formation, and
Sprout-formation, we could not avoid recognising sub-
ordinate kinds of reproduction, since we could not deny
even to the cell, but especially to the sprout, a certain
individual import ;—so, on the other hand, the series of
individuals produced by true reproduction appears as an

* As in the cases of flowers appearing green, (anthochloroses,) in which
all parts of the flower often return more or less perfectly into the euphyllary
formation. 21

322 THE PHENOMENON OF

interlinking (Gliederung), only in a free condition, and the
species as a whole, developing itself in this formation of
links, as it were a vegetable “ stock” of a higher kind.
That we might go still further in this direction, in the
attempt to seize the conception of the natural continuity
of the essence, we have already indicated in the Intro-
duction. For as the individual appears as a link of the
species, so does the species as a link of the genus, the
genus as a link of the family, of the order, the class,
of the kingdom; the kingdoms of Nature even as the
great principal links of the organism of Nature; a view
with which, indeed, we give to the Natural System its true
and objective import, which is entirely lost in the mere
subjective abstract conception of the natural divisions.*

* The true recognition of the organism of Nature and its composition of
members or links, as objective facts, expressed by Nature itself, is essen-
tially necessary to the higher shaping of Natural History as a unity. The
tendency existing in the contrary direction, disregarding one-sided philo-
sophic hypotheses, is caused among botanists chiefly by the previously pre-
vailing cultivation of the Artificial system, and the difficulty of the con-
struction of the truly Natural. Linneus himself, moreover, the founder of
the most important Artificial system in botany, regarded species and genera,
emphatically, as objective works of Nature, (‘Phil. Bot. § 162,) and
explained the classes and orders of the Artificial system as a makeshift, until
the Natural were detected, ($ 161.) It is remarkable to find even such
authors as are inclined to an objective view of the conceptions of the
genus and species, making the assertion that merely the individual really
exists, (thus e. g. in Spring, ‘Ueber die Naturhist. Begriffe von Gattung,
Art und Abart,” 1838, p. 22, 23.) To acknowledge the individual as really
existing, and deny the natural actuality of the more comprehensive com-
plexes of the organism of nature, is an inconsequence, depending on the
deception by which the individual seems to be immediately given in the
phenomenon, while it is easy to see that the individual, as such, 7. e., as a
single being, can only be conceived mediately, in the recognition of the inner
unity which runs through the series of phenomena, in which it displays
itself. Child, youth, and man, caterpillar, chrysalis, and butterfly, are not
to be conceived from external appearance, but only in consequence of their
immaterial essence, as one and the same single being. The external con-
tinuity of the successive series of appearances of the individual, affords no
ground for regarding it essentially differently from the comprehensive sys-
tematic complexes, for the same recurs even in the successive appearances of
the species, where successive links (the individuals) stand in direct con-
nection in the reproduction. That the individual has no right to be
considered as real in other senses than the species, genus, &e., is indicated
especially in the alternation of generations, as it is called, which exhibits the
remarkable case of the individual, in the higher sense, (the biological
individual,) breaking up into a limited or unlimited series of subordinate

REJUVENESCENCE IN NATURE. 323

It is true that the common origin and the historical con-
nection among the links of the more comprehensive
divisions of the Vegetable Kingdom, cannot be so readily
demonstrated as is the case with the history of the
individual in Cell-, Leaf-, and Sprout-formation, and the
history of the Species, the formation of the Individuals

(morphological) individuals, which sometimes are developed in permanent
connection, as compound family-stocks, as in the “stock” formation of the
zoophytes and plants, caused by sprout-formation, sometimes separate com-
pletely, as in the Entozoa, Aphides, Medusz, and in the case not unfrequent
in the Vegetable Kingdom, of natural separation of the buds. Indeed
Nature goes still further in plants, for it gives to the smallest circles of
formation subordinate to the morphological individual, usually called the
cells, such an independence of the vital functions, that these may be
regarded in a certain sense as individuals, which, in the higher plants, lead
a life interwoven in the totality of the organism, but in the lower, separating,
often acquire an isolated individual existence, (pp. 124, 125, et seq.,) in
both cases representing an alternation of generations of subordinate kind in
their succession and multiplication, effected by a process analogous to repro-
duction. According to the axiom that merely the individual really exists,
those who recognise the individual of the plant in the cell, must interpret
the cells of the plants as alone real beings, and the stock, the sprout, the leaf,
&c., as inessential aggregates. But where remains the individuality of the
cell, as external appearance, when we see that even this has its transforma-
tion, its successive renovation, so that, externally regarded, it does not
remain the same, but constantly becomes another, so long as the vitality
endures in it, (pp. 176 et seq., 226 et seq.)? The reality, therefore, can-
not be immediately conceived, not even the smallest circle, in the detached
phenomenon, but in every case only mediately in the recognition of essence
on which the continuity of the phenomenon depends. Now just as the
individual is realised through a chronological succession of formations and
material division into subordinate links, this is likewise realised in a
complex of a higher order, represented by the individuals, by means of which,
just as in the individual, it runs through its circle of forms in chrono-
ee succession and material extension; in like mauner the genus, as a
more highly generalised whole, is realised through the circle of the species,
the family through the genera, &c.; so finally Nature, as a whole, is realized
through the process of development, which brings into existence all the
links of its organism, successively and contemporaneously, and the totality
of each system of links in all these circles certainly cannot be called less
real, in its representation through the links, than the parts which, without
the whole, would not exist. For the assertion that merely the individual is
real to have any meaning, the species, genera, families, classes and kingdoms,
must be regarded as individuals of a higher order: a view which may be
considered well founded, in so far as all these complexes depend upon
special practical destinations of natural life, just as Nature, as a whole, as
shaped out upon our planet, is to be regarded as an individual, which,
although created according to the same eternal primary type, certainly
possesses its own mode and way, different from the Nature of the other
celestial spheres.

324 THE PHENOMENON OF

effected by reproduction, and the circle of Varieties which
come into existence in the course of reproduction ; but
the flora of the ancient world,* and the geographical
distribution of the plants of the present epoch,t afford us
important indices at least, pointing to the connection in
time and space of the history of development of the
Vegetable Kingdom as a whole and in its parts.

We have examined Rejuvenescence in general and
more particularly in the processes of Vegetable life, and
rising from the narrower circle of the development of the
single being, we have sought for it again in the wider
circles of the Organism of Nature, and in this way arrived
at the conviction, that it lies at the foundation of all sub-
division in life, all graduated development; that it is
this, through which not only the single being progresses
from one formation to another, but the whole chain of
being is carried onward from generation to generation ;
through which the smallest step of the organic structure
is introduced, the greatest transitions of Nature carried
into effect, and the metamorphosis in the individual, like
the transformation of Nature as a whole from age to age,
brought about. At the conclusion, then, of our reflec-
tions, the question will not appear premature, if we ask,
What property of life it really is which declares itself in
the Phenomenon of Rejuvenescence? In the first place, a
general acknowledgment must be made that the orderly
succession of phenomena of Rejuvenescence, which pre-
sents itself to us in every natural development, cannot be
explained through the effort of external natural forces,
but points to an internal cause. Every train of develop-
ment exhibits in its course an adherence to plan which

* See pp. 7—9. The law of development becomes more and more
evident in the newer works on the character of the vegetable kingdom in
ancient epochs. See, in reference to this, the latest comparative view by
Ad. Brongniart, in his ‘ Tableau des genres de Végét. Fossiles,’ p. 93, (1849.)

t Note, for example, the native country of the family of Cactex, the
cactus-like Euphorbiz, the Epacridee, the group of the Heliophilex in the

uy of the Crucifere, the rich genera Stapelia, Pelargonium, Aloe, Agave,
oC.

REJUVENESCENCE IN NATURE. 325

can only have its ground in an internal vital destination ;
it exhibits, at the same time, an independence of all
external influences which testifies to the internally given
force of vitality. The manner and way in which the
internal immaterial nature of life manifests itself more
particularly in the Phenomenon of Rejuvenescence, we may
call, in the true sense of the word, a reminding (Brin-
nerung), being the exertion of a power which, in opposi-
tion to the outward revelation and superannuation of life
in appearance, grasps anew the ideal (innere) destination
and turns it outward with new force, in order to carry it
over every onesidedness or imperfection in the external
representation, to repeated (and in proportion to the pro-
gress of the development) more and more refined com-
plication of the original vital purpose. The recollection
(or reminding) of the inherent design of life presents
itself to us within the determinate stage of development
in the repeated representation of the same vital form ; it
presents itself to us, retrogressively, in the reproduction
of long overpassed, or, in advancing development, in the
production of new vital forms, which are, in both cases,
however, involved in the original destination. Must we
not call it a reminding (or recollection) when, in the
course of generation, the old specific nature returns to
life with each new individual? It is not still more
strikingly a reminding when, in the course of the Reju-
venescences, a long-relinquished parent-form suddenly
returns to existence? as we have seen in the striking
back of varieties and the recurrence of hybrids into the
mother-species, with so remarkable an instance of which
we have become acquainted in Cytisus Adami? The
advance to new shapes, proportioned to the course of
development, brought about through the Rejuvenescence,
has been minutely examined in the metamorphoses of the
individual being, where it is most accessible to our limited
observation; does not this reveal most distinctly the inter-
nal preservation and making good of the original vital des-
tination, through all intermediate destinations which are

326 REJUVENESCENCE IN NATURE.

required for its entrance into combination with the lower
steps of nature, from which the development starts? As
in the Individual, then, so certainly in all Nature, with
which the individual is combined through the common
destination lying at the very foundation of all life. This
connection is testified to us by the unity of the final term,
in which we see the structure of entire Nature receive its
key-stone. Is it not here again the recollection of the
original destination of created life, which carries up step
by step the development of Nature, from the first stirrings
of life, through infinitely numerous links of Reju-
venescence, to the appearance of Man? Finally, is it
not this which impels even Humanity to Rejuvenise itself
from race to race in ever more deeply searching recollection
of its high purpose, comprehending that of all Nature,
and connecting it with the Eternal Source whence all
internal Law and Force of Life derive their origin ?

MACROCOCCA. Kurz?

LOA
Pak

OG

PALM

+ Chromo Em

Ford & We

Fatlen West Chramo Lith

EXPLANATION OF THE PLATES.

PLATE I.

Palmoglea macrococca, Kützing ?*
(Coccochloris Brebissonii, Thwaites).

All the figures are from specimens from the Höllenthal,
near Freiburg. The figures 21—28 and 1—13 of
Pl. II represent the conjugation of the cells, and the
consequent formation of the spores, as described at
pp. 135, 202, and 285 of the text. Magnified 350 diam.

Fig. 1. Acell with a distinguishable gelatinous envelope.

Fig. 2. A cell which has attained the maximum of
longitudinal growth.

Fig. 3. A cell beginning to divide.

Fig. 4. A pair of cells produced by division, the two
portions still in contact.

Figs. 5 and 6. The same, but the two daughter-cells,
still enclosed by the common enveloping membrane of
the mother-cell, have already separated, without however
exhibiting distinguishable special envelopes.

Fig. 7. Two cells, considerably elongated and possessing
special coats, enclosed by the common mother-envelope.

Fig. 8. A cell of moderate length with two vesicles in

* The species of the genus Palmoglea, established by Kützing, cannot be
Eee! determined either by the characters given in the ‘Spec. Algarum,’
or by the figures given in the ‘Tabula Phycologice.’ In the species
represented in our plate, the jelly-like cell-envelopes are sometimes dis-
tinguishable singly, sometimes not, which renders doubtful evert the section
in which we are to seek the species. The germ-cells vary in length from
ay to # millim., average, therefore, +4, to 4 of a line, so that the distinctions
founded on size, given by Kützing, likewise furnish no safe criterion.
From the variability of the characters, it is not improbable that many of the
species brought forward by Kützing, in particular P. rupestris, macrococca,

vesiculosa, lucida, rufescens, and crassa, will have to be combined as forms of
one and the same species.

328 EXPLANATION OF THE PLATES.

the interior, the nature of which is doubtful; between
the two, and more to the side, exists a lighter space
(frequently observable). j

Fig. 9. A similar cell, in which the dark-green portion
of the contents forms a pretty sharply circumscribed
mass with a constriction in the middle.

Fig. 10. The same cell turned one quarter round, the
green mass appearing narrower and with a bright spot
beside it. :

Fig. 11. Another cell in the same position, with a still
more compressed green body in the interior, reminding
us of the genus Mesotenium, Nag. (‘Einz. Algen.,’
t. Iv, B.)

Fig. 12. The same cell seen from above.

Fig. 13. A similar cell, in which the plate-like green
mass is interrupted in the middle.

Fig. 14. Two very short cells, shortly after their pro-
duction by division, with plate-like compressed green
masses placed obliquely in the interior.

Figs. 15—16. Rows of cells in contact, without dis-
tinguishable enveloping membranes, such as are some-
times produced by rapidly succeeding divisions in very
active vegetation. The arrangement of the cells in this
case shows that the division constantly occurs only in
one direction.

Figs. 17—20. Cells treated with tincture of iodine,
whereby the green masses in the interior are coloured
brownish, and a dark brown nucleus becomes visible,
which, however, does not appear sharply defined, and
certainly contains no starch.

Fig. 21. A cell preparing for conjugation, furnished
with a lateral wart-shaped projection.

Fig. 22. Two similar cells in contact by their wart-
shaped projections.

Figs. 23—27. Cells conjugated by union and anas-
tomosis of the lateral processes, with the connecting
piece of variable length.

Fig. 28. The same, but one cell crossing the other.

1 i en es ep
Taffom West Chramo Lith 29, rar any ed

15.22 SCHIZOCHLAMYS CELATINOSA

114 PALMOGLIEA

ne

EXPLANATION OF THE PLATES. 329

PLATE II.

Figs. 1—14. Palmoglea macrococca.
(Continued from Pu. J.)

Fig. 1. Two cells, laterally connected, pushed aside
in opposite directions.

Figs. 2—4. Conjugated cells, in which the end of one
is attached to the side of the other.

Fig. 5. Conjugation carried further, by the widening
of the connecting piece. (The cells from fig. 21, pl. 1, to
this figure, already exhibit evident drops of oil in the
interior.)

Figs. 6—9. Transitional forms produced by still fur-
ther advanced conjugation, but still two-lobed; they
often persist in this form.

Figs. 10—12. Seed-cells formed by complete union
of two conjugated cells. These, as also those represented
in 6—9, are almost filled with large drops of oil, and
have a thicker coat than before the conjugation.

Fig. 13. Seems to be an union of three cells, which I
only met with once.

Fig. 14. A group of four cells, enclosed by a tough
coat, probably produced by the division of the contents
of a seed-cell.

Figs. 15—22. Schizochlamys gelatinosa, A. Br.

This forms a gelatinous coating over water-plants, as
also swimming masses, on the peat-moors of the Black
Forest. (See pp. 181, 230, in the text.) Magnified 600

diameters.

Figs. 15—16. Two cells which throw off their cell-
membrane by regular splitting into two halves, without
themselves dividing.

. Fig. 17. A cell which, after throwing off its earlier

330 EXPLANATION OF THE PLATES.

’ cell-membrane, has formed a new one, somewhat removed
from the green internal cell at one side.

Fig. 18. The cell-membrane thrown off by splitting
into four pieces, with simultaneous division of the cell
into two daughter-cells.

Fig. 19. As in fig. 18; but the two new cells have
already become coated with cell-membrane.

Fig. 20. The same; but the detached cell-membrane
split only into two parts.

Fig. 21. The detached cell-membrane has broken up
into four portions, the internal cell has become trans-
formed by double halving into a group of four decus-
sating cells.

Fig. 22. The same; but the cells have already
separated and become coated with new cell-membrane.

PI IM

PEDIASTRUM GRAMUILATUM

Tuften West Chromo Lith Cord & West Chromo inp

EXPLANATION OF THE PLATES. 3831

PLATE III.
Pediastrum granulatum, Kütz.*

Numerous modifications, all derived from one and the
same little pool of water, near Freiburg. Figs. 1—9
represent the reproduction. (See pp. 161, 184, 200,
250.) Magnified 400 diameters.

Fig. 1. An old disk, in great part emptied by birth of
gonidia. The emptying of the cells of this specimen,
the first in which I observed the reproduction, took place
before my eyes in the order of the letters a to e; this was
on a day in autumn, (Nov. 24, 1848,) in the afternoon ;
the empty cells not marked had lost their contents before
the commencement of the observation, probably in the
morning of the same day. Several of the empty cells,
(for instance, a, 4, c, e,) distinctly exhibit a cross slit,
through which the contents have been discharged ; in the
rest the emptying has taken place on the opposite side,
so that the slit is invisible in this position of the disk. One
cell is in the act of discharging the gonidia, these having
in part entered into the projecting portion of the hernia-
like vesicle formed by the swollen innermost lamella of
the mother-cell membrane, in part still remaining in the
internal cell-cavity. Three other cells still possess their
perfect contents, but in different conditions. Two of
them are filled by sixteen extremely closely crowded
gonidia, only half of which are visible, as they form a

* In giving a name to this species I select that determination which
seemed least doubtful; I must observe, however, that several of the species
distinguished by Kützing probably belong to the same species, so particularly
P. Boryanum, K.; subulatum, cruciatum, K.; and also in part P. Selena,
Auct., namely, with the exclusion of P. Selenea, Ralfs., (lunare and elegans,
Hass.); and P. Seleneu, Nag.; (pertusum, K.) The length of the horns,
as also their clavate rounding off, is variable; punctated condition of the
cell-wall, on the contrary, I found constant; but it is only distinguishable in
full-grown and empty specimens.

332 EXPLANATION OF THE PLATES.

double layer. The third, not yet emptied cell, is in the
actual transition to the formation of gonidia ; it exhibits
the first divison of the contents into two halves, one of
which already appears halved again. —The arrangement
of the sixteen cells of the entire disk is an unusual one,
1+6-+-9, the outer circle in this case being incomplete,
and a cell of the inner circle, opposite the break in the
outer circle, possesses one horn.

Fig. 2. The new-born family, immediately after the
birth, seen from the corner. It is derived from the cell
a of the disk represented by figure 1. The innermost
lamella of the mother-cell has wholly emerged from the
old cell as an extremely thin vesicle enclosing the
gonidia ; the gonidia in the interior of the mother-vesicle
moving actively.

Fig. 3. The same family, in the same stage, seen on
the surface.

Fig. 4. The same, in a later stage, namely, a full
quarter of an hour after birth, in the same position as
fig. 2. The gonidia, now at rest, have arranged them-
selves in a plane in the plane of section of the equator of
the mother-vesicle.

Fig. 5. The same, in the same stage, showing the
surface. The sixteen gonidia, united into a colony, form
a circular sixteen-celled disk, in the arrangement 1-++5
-+-10; but they do not adhere firmly together. A slight
emargination is already visible on the outside border of
the cells.

Fig. 6. Another young family in the same stage as
fig. 5, about half an hour after birth. The arrangement
BL.

Fig. 7. Another of the same age, exhibiting the
arrangement 6-+- 10.

Fig. 8. The families represented in figs. 2, 3, 4, 5,
one hour after birth. The emargination of the cells has
advanced further.

Fig. 9. The same again, but four hours after the
gonidia ceased to move, (four hours and a half after

EXPLANATION OF THE PLATES. 333

birth.) The emargination of the border-cells has passed
into the formation of horns. The cells are not even yet
closely connected together, but exhibit spaces between
them, so that in this stage the disk exhibits a resem-
blance to that of Pediastrum pertusum, (Näg., ‘ Kinz.
Alg.,’ v.2, as P. Selenea,) which species, however, does
not lose the orifices in the full-grown condition. Not
until the second day, after an interruption during the
night, of the rapid changes of form of the cells, do the
cells become closely applied together; the horns acquire
their proper shape and length at the same time.

Fig. 10. A half-grown disk of four cells, two of which
meet in the middle. A starch-grain is visible in each
cell, as is usual in the middle age. The mother-vesicle
is still visible here, while in ordinary cases it disappears
altogether by the second day.

Fig. 11. An older four-celled disk, the four cells
meeting in the middle. The families formed of four
cells are extremely rare in this species.

Fig. 12. Disk of eight cells, in the arrangement 2-+6,
which is more frequent in this species than the arrange-
ment 1+7. The inner two cells are notched on the
outer border, which is connected with the position of the
two outer cells opposite to them.

Fig. 13. A similar disk, but with the inner two cells
not notched, but interposing an obtuse-angled prolonga-
tion into the commissure of the outer cells alternating
with them.

334 EXPLANATION OF THE PLATES.

PLATE IV.

Pediastrum granulatum, Kg.

(Continued from Pu. Ill.)

Fig. 1. Disk of eight cells, placed 14-7, derived from
the same mother-disk as the four-celled disk represented
in fig. 11, of Pl. 3.

Fig. 2. Full-grown eight-celled disk, 147. The con-
tents of the cells dark green, and granular; the starch-
grains no longer visible. The cell-walls in the interior
of the disk are tinged slightly crimson, which colour,
however, only occurs sometimes in full-grown specimens.

Fig. 3. Eight-celled disk arranged 146-1, a very
rare exceptional case.

Fig. 4. Disk in 1+5--10, which is the most frequent
case with sixteen cells, (see fig. 5, Pl. IIT.)

Fig. 5. Disk of sixteen cells, 6--10, the inner six
differently arranged from those of fig. 7, Pl. III.

Fig. 6. A similar one, but the outer circle so closely
adjoined to the inner that the arrangement appears
spiral.

ae 7. Abnormal disk of fifteen cells, in which, how-

ever, one in the outer circle is larger than the rest, and
doubtless stands in the place of two, from omission of the
last division in the formation of gonidia. The likewise
irregular arrangement may, therefore, be regarded as
5+10+1.

Fig. 8. Elliptical disk of sixteen cells, 54-10.

Fig. 9. A similar disk, but the five inner cells in a
different position.

Fig. 10. Elliptical disk of thirty-two cells, 7-+-11-++14.
The colonies of thirty-two cells are rarer in this species

LANULATUM

PEDIASTRUM

EXPLANATION OF THE PLATES. 835

than the sixteen-celled ; I have observed in these, besides
that figured, the following kinds of arrangement :

14+5 410+ 16
1464104 15
145411415
1+6 +11 + 14 (spiral.)
5+11+16
6 + 10 + 16 (sub-spiral.)
7+10+15 (elliptical.)

I have never met with specimens with sixty-four cells
in this species, but Nägeli, (l. c., t. v, B, 1, g,) figures a
sixty-four-celled specimen, arranged 2+7-+12-+19+24,
in the scarcely specifically distinct P. Boryanum.

336 EXPLANATION OF THE PLATES.

PLATE V.
Cytisus Adami.

Diagrams of mixed flowers, partly striking back to
Cytisus Laburnum, on which see p. 319 in the text. The
outer circle represents the calyx, the brown parts of it
belong to C. Adami, the green to C. Laburnum. In the
inner circle (corolla) the red colour signifies C. Adami,

the yellow C. Laburnum.

ForL& West Chromo Imp

Tuffen West Chromo Lith

HYBRID FLOWERS FROM CYTISUS ADAMI & © LABURNUM

INDEX.

Acalypha, 89.
Acanthus, 92.
Achillea, 30.
Achlya v. Saprolegnia.
Aconitum Napellus, 37.
Acta, 55, 73.
Adonis vernalis, 84.
Adoxa, 29, 31, 55.
Adventitious buds, 22.
Ajuga genevensis, 22.
isma, 98.
Allium Schonoprasum, 97.
Alnus glutinosa laciniata, 332.
Alternations of generations, 51, 52,
106, 126, 322.
Altheea rosea (Pollen-formation), 256.
Ampelider, 94.
Amylum v. Starch.
Anabaina, 146.
Anagallis, 22.
‚Ananas, 57.
Anaphytosis, 102.
Anarrhinum bellidifolium, 71.
Anemone nemorosa, 29, 55.
Angelica sylvestris, 86.
Anthoceros, 257.
Apetalous flowers, 94. (250.
Aphanochete, 184, 209, 230, 233,
Apiocystis, 132, 209.
Apios, 33.
Aquilegia, 99.
Araucaria, 59.
Archidium, 232.
Armoracia rusticana, 97.
Aroides, 89, 91.
Arthrosiphon, 178.
Ascidium, 125, 127, 185, 186, 200,
Asimina, 79. [209, 267, 286.
Asparagus, 44.
Aspidium remotum, 310.
Aster, 30.
Balsaminex, 33.
Bambusina, 291, 295.
Bartonia, 248, 252.
Batrachospermum, 150, 151.
Beech v. Fagus.
Berberis, 77, 90.
Betula alba laciniata, 312.
Betulaces, 91.
Botrydium, 128, 193, 220, 274.
Botryocystis, 159, 209.

Breadth of the base of leaves, 67.

Bromus, 40.

Bryopsis, 129, 140, 166, 268.

Buds, 18.

descent of, 56, 57.

Bulbochete, 141, 151, 156, 157, 183,

201, 209. [308.
pretended conjugation of,

Bupleurum rotundifolium, 86.

Buxus, 36.

Calliopsis bicolor, 85.

Calluna vulgaris, 226.

Calycanthus, 77.

Campanula medium, 98.

Carex, 101.

Carpels, 65.

Carpinus, 36, 53, 62.

Castanea, 89.

Cataphyllary leaves, 62, 84.

Caulerpa, 129, 174.

Cell-contents, 155, 171.

solutions in this, 194.

Cell-formation, 121, 123.

abnormal, 266, 281.
free, 164, 167, 238,
259, 272, 275.
by constriction, 254.
by division, 168, 232,
240, 250.
period of, 224.
Cell-membrane, 156, 176.
lamination, 220, 229.
solution of, 189.
stripping of, 18, 230.
tearing up of, 177.
skinning of, 180, 188.

Centunculus, 34.

Chetomorpha, 185, 186, 268.

Cheetophora, 139, 151, 156, 183, 208,
224, 231, 253.

Chantransia, 143, 151, 183, 231.

Chara, 221.

Characez, 152, 175, 234, 247. [250.

Characium, 125, 185, 209, 229, 230,

Cheiranthus Cheiri gynantherus, 97.

Chelidonium magus, 77.

Chimonanthus, 78.

Chlamidococcus, 138, 158, 174, 184,
196, 205, 211, 216, 224, 229, 238,
250, 258.

Chlamidomonas, 214, 216.

22

338

Chlamidomonas, obtusa, 215.
tingens, 215.
Chlorococcum, 213, 260.
Chroococeacez, 131, 174, 190, 197.
Chroococcus, 131.
decorticans, 182, 230.
Chytridium, 185, 261.
Cicendia filiformis, 25.
Cilia of the Alge, 157, 158.
disappearance of, 230.
Citrus Medica, 82.
Cladophora, 150, 174, 185, 199, 220,
235, 236, 239, 240, 253, 268.
Closterium, 133, 175, 281, 291.
acerosum, 291.
curtum v. Penium.
juncidum, 292.
eibleinii, 292.
lineatum, 291, 292.
Lunula, 140, 204, 289.
striolatum, 292.
Trabecula v. Docidium.
Coccoloba, 60.
Cocconema, 286.
Coleochzte, 141,270. [258, 298.
pulvinata, 151, 183, 208,
scutata, 142, 183.
Commarum, 78.
Composite, 85, 89.
Conferva bombycina, 184, 205, 209.
Conjugation, 282, 283.
of similar cells, 284.
of dissimilar cells, 296.
Convallaria, 34, 68, 90.
Corypha umbraculifera, 27.
Cosmarium v. Euastrum.
Crassulacez, 94.
Crocus, 67.
Cruciferee, 33, 90, 96, 97.
Cuticle, 191, 244.
Cycas, 12, 27, 58.
Cyclamen, 34.
Cylindrocystis, 287.
Cylindrospermum, 146.
Cymatonema, 141.
Cyperacee, 33, 91, 98.
Cystococcus, 125, 185.
Cystoseira, 248.
Cytisus Adami, 24, 31. (315.
Laburnum quercifolius, 312,
„ Derbesia, 185, 186.
Desmidiacex, 133, 139, 174, 247,
283, 290.
conjugation of, 290.
movenient of, 203.

INDEX.

Desmidium, 294.

Destruction of the Cell, 176.

Dianthus, 76.

Diatomacex, 132, 139, 190, 247.

conjugation of, 285.

Diclinous flowers, 100.

Dictyospherium, 132, 209, 238.

Didymoprium, 291, 295.

Digitalis purpurea monstrosa, 58.

Diphyscium foliosum, 177, 230.

Division of Generations, 36.

Docidium, 291.

Trabecula, 180.
Doubling of Flowers, 79.
Draparnaldia, 139, 151, 156, 183,
Drosera, 98. [208, 224, 231.
Dysphinctium, 203.

Ectocarpus, 125, 142, 185.

Elymus Europzus, 87.

Emilia sagittata, 86.

Endococeus, 213, 268.

Endosperm-cells, 248, 278.

Enrichment-sprouts, 37.

Enteromorpha, 184, 250.

Epilobium, 30.

Epimedium, 55, 73, 77.

Equisetum, 180.

Ericacex, 94, 97.

Eriocaulon, 35.

Erysiphe, 261.

Erythrea pulchella, 26.

Euactis, 147, 178.

Euastrum, 133, 224, 295.
margaritiferum, 181, 294.
Meneghinii, 300.

Eunotia, 286.

Euphorbia, 22, 36, 37.

Euphyllary leaves, 63, 84.

Exococcus, 254.

Fagus, 20, 31, 62.

sylvatica sanguinea, 312.
asplenifolia, 315.

Fasciation, 122.

Fermentation Fungi, 254.

Ferns, 27, 307, 309.

hybrid, 309.

Festuca, 40.

Fir v. Pinus.

Floridex, 253, 255.

Fragaria vesca monophylla, 312.

Fraxinus excelsior simplicifolia, 312.

Fuchsia, 78.

Fucoides, 142, 183, 253.

Fucus, 126, 142, 183.

Fuirena, 91.

INDEX.

Fumaria, 79, 90.

Fundamental organs of the plants,
108, 112.

Funkia cerulea, 276.

Galanthus nivalis, 56.

Generations, successions of, 32.

division of, 35.
alternations of, 51, 52,
106, 126, 344.

Gentiana, 83, 92.

Geraniacez, 93.

Germ-cells, 134.

Germinal vesicles, 167, 276.

Gesneriaces, 33.

Glaux, 95.

Glechoma hederacea, 59.

Gleichenia, 114.

Gleeocapsa, 131, 132, 182, 190.

Gleococeus, 159, 209.

Gleeocystis, 131, 161, 182, 190.

Glyceria aquatica, 87.

Gomphonema, 238, 286.

Gongrosira Sclerococcus, 183, 209.

Gonidia, 134, 137, 140.

active 137, 141, 148, 157,
158, 162, 169, 183, 261.

duration of motion of, 212.

period of motion of, 221.

Gonium, 159.

Graminew, 33, 86, 91, 98, 100.

Hematococcus pluvialis v. Chlamy-
domonas.

Halving of cells, 233.

Haplosiphon, 150.

Hassallia, 150.

Hedysarum coronarium, 33.

Heliconia cannoidea, 73.

Helichrysum arenarium, 22.

Helleborus foetidus, 72, 76.

niger, 29, 55.

Hepatica, 29, 54, 314.

Heracleum, 69.

Himantidium, 286.

Hormidium, 131.

variabile, 208.

Hyacinthus, 18.

Hyalotheca, 291, 295.

Hybrids, formation of, 42, 310, 316.

Hydrocharis, 101.

Hydrodictyon, 125, 127, 187, 156,
171, 185, 186, 190, 197, 199,
208, 219, 220, 261.

Hydrophyllum canadense, 72.

Hymenophyllum interruptum, 115.

Hypecoum, 79.

339

Hypericum, 28, 30.
calycinum, 77.
Hypnum abietinum, &c., 40.
Hypsophyllary leaves, 63, 84.
Impatiens Balsamina, 35.
Increase-sprouts, 38. (124.
Individual, the vegetable, 19, 23,
Tsoétes, 28, 53, 144, 189, 197, 200.
Isoetacex, 255.
Isthmosira, 291, 295.
Jacquinia, 79, 93.
Jamesonia, 1] 4.
Jasione perennis, 71.
Jasminee, 93.
Juncus, 97, 107, 111.
Juniperus, 59, 65.
Jurinea Pollichii, 22.
Labiate, 33, 90, 98.
Leaf-formations, 51, 101.
of the Alge, 152.
disappearanceof,83.
Leafy-shoots, 57.
Leaves, formation of 62, 84.
Leguminose, 33, 90, 99, 194.
Lemania, 154.
Length of leaves, 70.
Leptomitus lacteus, 270.
Ligustrine, 33.
Lime v. Tilia.
Limnanthes, 96, 99.
Linaria, 22, 31.
Litorella lacustris, 42.
Lolium, 40, 87.
Lycopodiaces, 144, 255.
Lycopodium annotinum, 59.
Lysimachia Nummularia, 31, 34, 59.
Lythrum, 30, 80.
Mahonia, 70, 71, 77, 90, 96, 115.
Malvacex, 94, 96, 99. i
Marsilia, 194,
Mastichonema, 147, 187.
Mastichothrix, 147.
Melaleuca, 57.
Melocactus, 27.
Melosira, 139, 299.
Mentha, 28, 30.
Mertensia, 114.
Mesocarpus, 135, 288.
notabilis, 289.
Metamorphosis, 60, 320.
ascending, 60.
descending, 52.
vibrating, 52.
Mirabilis Jalappa, 315.
Monsonia, 93, 96.

340

Mosses, hybrid, 310.
Mougeotia, 288.
Musa, 74.
Myrtacex, 98.
Nardus, 87.
Narcissus, 53, 56, 80.
Nasturtium pyrenaicum, 22.
Nicotiana, 92, 98.
Nostoc, 145, 155.
Nucleus, 174.
division of, 241, 248.
solution of, 195, 241, 248.
Nymphea, 79.
Oak v. Quercus.
Gdogonium, 14], 148, 150, 156,
157, 161, 163, 170,
175, 183, 196, 201,
209, 212, 224, 227,
231, 247, 281.
apophysatum, 141, 162, 301.
capillare, 170.
echinospermum, 141, 302.
fonticola, 141, 170, 224.
Landsboroughii, 164, 301.
supposed conjugation of, 300.
Gnothera biennis-muricata, 42.
muricata, 71.
Oil (fixed), 193, 195, 200.
disappearance of, 204, 205.
Ophiocytium, 260.
Ophioglossum, 18, 59, 189.
Orchidez, 33.
Ornithogalum sulphureum, 276.
Oryza, 88.
Oscillaria, 131, 197.
Oxalides, 93.
Oxalis Acetosella, 54.
stricta, 30.
Oxyria, 77.
Pachysandra, 35.
Peonia, 71, 73.

Moutan, 96, 99.
Palmellacew, 131, 174, 190, 213.
Palmoglea, 133, 135, 202, 285.
Pandorina, 159, 209, 212, 224. ~
Panicum mirabile, 88.

Papilionacex, 98.
Paris quadrifolia, 26, 34. j
Parnassia palustris, 226. [249.
Passiflora (Pollen-formation of), 248,
Pediastrum, 125, 161, 184, 200, 209,
Pedicularis palustris, 71. [250, 266.
Penium, 292.
curtum, 181, 190, 203.
Jenneri, 289.

INDEX,

Perigynium, 100.
Petals, 64, 93.
Peziza, 186, 260.
Phaseolus, 33.
Phlox paniculata, 72, 76.
Phyllotaxy, 116.
Physalis Alkekengi, 30.
Phytolacca, 95.
Pinus, 32, 39.
(Pollen-formation of), 248,
249, 256, 257.
Plantago lanceolata, 57.
major, 35.
Platyzoma, 114.
Pleurococeus, 131, 258. :
miniatus, 182, 213, 230.
Poa alpina, 57.
bulbosa, 57.
Podophyllum, 77.
Polemoniacex, 33.
Pollen-grain, 228, 254.
Polygala, 77.
Polygovew, 94, 97, 98.
Polygonum,96 (vide addend.et corrig.)
Prasiola, 131.
Primordial utriele, 156, 169, 170.
Primulacex, 33, 95, 97, 99.
Propagation of cells, 227.
Protococcus, 125, 127. [258.
viridis, 209, 212, 213,
Pteris aquilina, 59.
Pulmonaria officinalis, 71.
Pyrola, 55.
Quartering of cells, 254. (71.
Quercus, 18, 20, 31, 36, 54, 62, 65,
pedunculata sanguinea, 313.
Rafflesia, 26.
Reconstruction of the Cell, 226.
partial, 272.
with halving, 232.
with quartering, 254.
with division into
many portions, 259.
Resorption of cells, 193.
Respiration of plants, 217.
Rhamnee, 94.
Rheum, 96.
Rhizocarpee, 144, 255, 256.
Rhododendron, 54.
Rhynchonema, 289.
Ribes, 78, 314,
Rivularia, 147, 148.
Rivulariex, 146, 178.
Robinia Pseud-acacia inermis, 319.
Root, 111.

INDEX.

Root-sprouts, 22.
Rosa Eglanteria, 314.
gallica, 315.
Rosacex, 98, 99.
Rubus Tdeus integrifolius, 312.
Rumex, 77, 100.
Rumex Acetosella, 22.
Rutacex, 80, 99.
Salvia, 90.
Salix, 53, 101.
Saprolegnia, 252, 268, 298.
capitulifera, 188, 269.
ferax, 185.
Sarcococca, 36.
Scenedesmus, 250.
Schizochlamys, 181, 230.
Schizonema, 139, 286.
Schizosiphon, 147, 178.
Sciadium, 187, 209, 260.
Scrophularinee, 33, 90, 98.
Scutellaria, 90.
Scytonema, 147, 178, 186.
Scytonemx, 146, 178.
Seed-cells v. Spores.
Sepals, 64, 92.
Series of generations, 32.
Sesleria, 87.
Sirogonium, 288.
Skinning of cells, 180, 188.
Slipping out of cells, 182, 231.
imperfect, 187.
Solanaces, 98.
Solanum tuberosum, 30, 37, 53.
Solidago, 30. i
Spermosira, 146.
Spheroplea, 164, 271, 281.
Spherozyga, 146.
Spirogyra, 135, 175, 180, 196, 201,
224, 239, 241, 281, 289.
lubrica, 244.
mirabilis, 300.
Spores, 134, 164.
Sprout-formation, 21.
relative to character, 38.

to economy, 38, 41.

Stamens, 64.
Starch-grains, 198, 206.
solution of, 195, 197.

Staurocarpus, 134, 281, 296.
Stauroceras, 287.
Staurospermum v. Staurocarpus.
Stellaria media, 95, 98, 99.
Stem-formation, 108, 110.
Stigeoclonium, 139, 156, 163, 183,

208, 224.

341

Strengthening generations, 29, 43.
Siruthiopteris, 108.
Sustaining sprout, 37.
Swarm-cells v. gonidia.
Swarming out of cells, 183.
Syzygites, 290.
Tamarix, 40, 98.
Tanacetum, 30.
Terminal bud, 53.
Tetmemorus, 291.
Tetrachococcus, 258.
Tetraspora, 132, 209.
Tetraspores, 255.
Thesium, 90.
Thuja, 40.
Thylis, 253.
Tilia, 45, 53, 100.
Tiliacex, 94.
Tolpothrix, 147, 186. [257.
Tradescantia (Pollen-formation of),
Transformation of pistils into_sta-
mens, 97. [278.
Transitory Cell, in the embryo-sac,
Trifolium montanum, 33.
Triticum, 40.
Tropsolum, 31, 39.
Tulip, 18, 26, 56, 68, 313.
Ulothrix, 125, 156, 159, 175, 200.
zonata, 148, 184, 208, 223.
Braunii, 177, 183, 208, 250.
Ulva, 125, 184, 250.
Unicellular plants, 124.
Urococeus, 178, 230.
Valeriana officinalis, 69.
Valonia, 180, 273.
Vaucheria, 128, 140, 157, 163, 174,
183, 209, 212, 221, 251.
conjugation of, 296.
Veratrum, 68.
Veronica Chameedrys, 59.
Vesicle, chlorophyll, 199.
Vesicles, germinal, 167, 275.
Vinca minor, 314.
Vines v. Vitis.
Vitis, 46.
vitifera laciniosa, 312, 315.
Volvocines, 158, 208, 216, 250.
eye of, 209.
Volvox, 159.
Willow, v. Salix.
Zonaria Pavonia, 179, 248.
Zygnema, 175, 288.
Zygnemacee, 133, 135, 164, 174,
Zygogonium, 288. [180, 287.
ericetorum, 177.

ON THE

ANIMAL NATURE OF DIATOMEA,

WITH AN

ORGANOGRAPHICAL REVISION OF THE GENERA,

ESTABLISHED BY KÜTZING.

By Proressor G. MENEGHINI.

TRANSLATED FROM

THE ORIGINAL ITALIAN EDITION,

(Venice, 1845.)

NOTE.

By an oversight, the references to pages in the Annotations, p. 496 ei seg.,
are erroneous, not having been altered to adjust them to the difference of
the paging in this volume and the original essay. The following corrections
must be made:—4—=346; 7= 348; 8=349,;, 9=350; 10—351;
123538; 13=354; 16= 357; 20360; 23= 363; 95 = 364;
90 = 421; 106= 445.

In reference to the discussion on the subject of measurement at p. 418,
it may be worthy of attention that Kützing confesses that Ehrenberg’s
figures, drawn with an amplification of 300, are not smaller, but sometimes
even larger than his own, which are magnified 420 times. (Note on
Epithemia ocellata, ‘ Kieselschal. Bacillarien,’ p. 34.)

ON THE

ANIMAL NATURE OF DIATOMEA.

Tue Diatomes are microscopic beings provided with
a siliceous shield or shell, on which account their form
remains unchanged ; they are easily subjected to observa-
tion, and easily distinguished from other minute organ-
isms, whether belonging to the animal or the vegetable
kingdom. The earlier observers considered them to be
animals undoubtedly; and animals they were decidedly
pronounced by Ehrenberg. On the other hand, almost
every Algologist has actually taken them for plants, and
in this opinion all are agreed who have more recently
treated on the elementary structure of organic beings,
and on the distinctions that constantly separate animals
from plants, even at their first origin. In support of
their animal nature, the important observations of Ehren-
berg certainly possess great value, but these are in-
sufficient ; because the same arguments have induced the
illustrious author to include in the same class of Poly-
gastric Infusoria the Desmidiez also, which now by
universal consent are acknowledged to be true Algz.

If a new opinion do not actually spring from between
these two, there is revived under another name the an-
cient theory of Phytozoa and Zoophytes, the Nemoures of
Gaillon, the Psychodiarian kingdom and the Arthrodiez
of Bory St. Vincent, the Green Matter of Priestley, the
metamorphoses of Agardh, and we are advancing directly
to the theory of spontaneous generation, and the other of
defective specific limitation, in accordance with which

346 ANIMAL NATURE OF DIATOMEE.

species and genera, whether animal or vegetable, are con-
sidered to be transitory forms of the same organic type.
Kützing does not admit any essential distinction between
animals and vegetables. He maintains that the same
being may, at various periods of its development, assume
one nature or the other. The following is his theory in
a few words. Every organic being is constituted of
vegetable elements and animal elements, and according
as the one or the other prevails, the being becomes an
animal or a vegetable; in the first stages of the develop-
ment of superior beings, and permanently in those of
inferior rank, the two elements are equally balanced.
And this is the case, in the author’s opinion, with the
Diatomez, which, on this account, cannot be absolutely
referred either to one series or the other, but constitute
the ring or circle which unites together all organic beings
into one kingdom. Long controversies have sprung up
between the supporters and the opponents of this doctrine,
who, to obtain victory, mutually accuse one another of
logical errors, of sophisms, and of paradoxes.

The analysis of this controversy would be tedious and
of little profit; whilst on the other hand, sound logical
principles may guide us to a rigorous estimate of the
facts. And, in truth, the natural sciences are entitled to
boast of a language that is adequate to the purpose, if
we avoid the abuse of Ontology. The words Animal and
Plant, like words in common use, as Species, Genus, Order,
Class, Kingdom, do not denote any existing thing in par-
ticular. To the naturalist there exist individuals only,
as to the philosopher there exist only bodies. Species is
a synthetical comprehensive expression, abstracted from
all the individuals so similar to each other, that they
may all be considered as originating from the same
parents. Genus is a still larger abstraction, comprehend-
ing all the species that resemble each other in some im-
portant characters; and so we advance to the denomina-
tions animal and plant, expressions of ideas existing only
in the mind of man, and therefore entirely subordinate

ANIMAL NATURE OF DIATOMEA. 347

to impressions already received and to those which may

“ be received hereafter. These ideas are hence more or

less incomplete in every observer, nay, incomplete in all,
because no one has seen every animal or every plant. On
this account we not unfrequently meet with organisms of
an ambiguous nature, which at first sight appear equally
to belong to the animal and the vegetable kingdom. But
yet with regard to this ultimate division of organic
beings, we ought to proceed in the selfsame path which
we find necessary to follow in respect to the first divisions
of Species and Genera. When a naturalist meets with a
species that appears to belong to two different genera,
and to form a transition, so to speak, between one and the
other, he decides according to the importance and the
value of the characters, either to modify the definitions
of the two genera, or to propose a new one, or to fuse
both together into one. He would sin against Ontology
should he assert that he found the two genera included
and combined in the ambiguous species. The genus has
existence only in our minds, and not in the species. In
the latter we can only discover some or all the charac-
teristics of the genus; that is, certain signs which con-
stantly subsist in every sister species, whatever may be
their diversity in other respects. Thus Kiitzing, when
he says that in the Diatomez the two elements, the
animal and the vegetable, are combined and in equilibrio
with each other, gratuitously imagines the idea of a com-
bination, which in reality can only take place between
different substances, and hence he applies his conjecture
to the expression, instead of applying the latter to the
former. And he draws his conclusion from the example
he uses, instituting this same comparison between the
organic and inorganic kingdom, and deducing from it
analogous consequences ; the gradual transition from one
to the other is as it were their conjunction, through
the same intermediate ring or circle of Diatomez.

The phosphate of lime, he says, which constitutes so
large a portion of the bones of animals, the silica of

348 ANIMAL NATURE OF DIATOMEE.

Diatomez, and the other mineral elements which are
found united with organic tissues both of animals and
plants, represent the combination of the inorganic with
the organic kingdom. According as the one or the other
prevails, life or death is triumphant. The word mineral
is in this instance so exalted, as to signify, not an in-
tellectual abstraction, but something unknown, ideal,
metaphysical. With the same right that he terms phos-
phate of lime or silica mineral, I can equally apply the
word mineral to carbon, hydrogen, or to the triple com-
bination of O. H. and C., or the quadruple combination
O. H. C. A., since these substances also, as well as the
former, do not solely of themselves manifest those general
properties which we comprehend in the abstract ex-
pression Zife. Nor ought we to allow ourselves to be
deluded by the abuse with which chemists apply the
word organic to some material elements of living beings.
It is a convenient but dangerous mode of expression.
The same remote elements constitute living and dead
bodies ; and admitting that some combinations are found
in the former which are wanting in the latter, and that
others can by no means be produced artificially, still
what we term /ife does not reside solely in these. The
same chemical combination may be alive or dead, without
any knowledge of the cause on our part. It is only by
comparing this with other known facts, and not by ob-
servation, that we suppose its proximate cause to be the
mutual arrangements and the motion of molecules. So
that, whenever any substance forms an integral portion
of the tissues of a living being, it does not belong to the
mineral kingdom, but to this being, and therefore to the
organic kingdom. It is only when, independently of
those manifestations which constitute life, this substance
within a living being obeys physical and chemical laws
as it would obey them out of the body, (like calculous
concretions within animals, and crystals in the interior of
vegetable cells, and incrustations whether internal or ex-
ternal,) so that they issue from the medium within which

ANIMAL NATURE OF DIATOMES. 349

they live or the vehicles that introduce them, and en-
viron, suffocate, and kill the animals or the plants or
their tissues :—then only I should denominate this sub-
stance a mineral thus associated with an organic being.
In the shields of a Diatomean, as well as in the discs of
Acalephz or-Gasteropoda, in the epidermis of Crustacea,
in the bones of Vertebrata, this so-called inorganic sub-
stance is, at least in part, within the same conditions as
the albumen or fibrine or any other proteine combination
which constitutes the rest of the tissue. In the Diatomee,
as well as in the Mollusca, the solid shield adapts itself
to the successively growing dimensions of the animal, as
in the Vertebrata the bones grow part passu with the
other tissues. And since this growth has nothing in
common with the crystallisation or successive deposition
of minerals, we are forced to allow that this manifestation
is of necessity comprehended in our idea of life.

Kützing, therefore, when speaking of Diatomez, ought
to have dwelt upon the fact that in these beings silica
exceeds the other material elements, and he ought only to
have instituted a comparison between the proportion of this
substance, and that which is elsewhere met with among
the other material combinations proper to organic beings
and at the same time common to them with minerals.
Perhaps he would have shrunk from this comparison, for
the more the second prevail over the first, the less is the
manifestation of life. But we are not endeavouring in
this place to learn whether a being is more or less easy
to be distinguished. A serpent coiled up and an eagle
circling the heavens are certainly different in their mani-
festation of life, but the one and the other is equally
different from a stone. Where life ceases, death takes
place; for these, being opposite states, admit of no tran-
sition.

The other opinion of Kützing, which, though foreign
to our present subject, we feel bound to oppose, is the
one which suggested to him the theory of two vitalities
combined together in eguilibrio or in inequilibrio. ‘The

350 ANIMAL NATURE OF DIATOMER.

same being, he says, may pass from the animal to the
vegetable nature, or from the latter to the former, and
again return to its original state. This opinion is not
new, for it was previously held by Agardh, by Gaillon,
and by Bory St. Vincent; but the facts which lead
Kiitzing to adopt it are so precise and so well described,
that they do not admit the easy charge of incorrect
observation, by which many have hitherto been satisfied
to answer arguments deduced from similar facts. He
sees microscopic beings corresponding exactly with the
descriptions and figures given by Ehrenberg, furnished
with organic peculiarities, and presenting vital phenomena
generally regarded by Ehrenberg and others as characters
of animal life, assume in their successive and natural
development, form, organisation, and life, such as are
generally attributed to plants. And from these plants
he sees reproductive bodies generated, similar to the
seeds of superior and spores of inferior plants, equally
endowed with characters of animality, becoming, however,
subordinated to those of vegetable life. ‘The fact is true,
and may be easily verified by any one in the habit of
making microscopic observations. And the explanation of
this fact appears to me equally easy. If there are beings
which, when they attain their perfect development, prove
themselves to be decidedly vegetable, although during
the first portion of their existence they presented some
phenomena of animal nature, this proves that those phe-
nomena do not exclusively belong to animals, and that
we cannot draw from them absolute characters of animal
nature. The imperfection, which we have already shown
to be inherent in every notion we can form of the animal
or vegetable kingdom, begins to diminish after such
considerations, and it is under this point of view that we
purpose to undertake the examination of Diatomes,
carefully separating in the characters they present,
those which they hold in common with vegetables from
those in common with animals, and inquiring if they do
not possess some exclusively with one or the other which

ANIMAL NATURE OF DIATOMEE. 351

may decide the question. The comparison of animals
with vegetables has been treated and discussed in all its
forms so many times, and by so many celebrated authors,
that the mere mention of ıt may excite a fear that we
are about to recite things antiquated or stale, or at least
well known by every one. Therefore I shall abstain
from the useless display of cheap erudition, and shall
apply myself solely to the most recent results of scientific
investigation.

The most certain manifestations of animal life are those
of sensibility and motion, either of the whole body or of
its various parts. It is useless to enter into minute par-
ticulars in order to prove that the word sensibility, like
all other abstract terms, is merely a name by which we
understand a class of phenomena whose cause is unknown.
Hence the abstract expression has come to denote the
cause itself, and by conventional agreement we say that
sensibility causes the phenomena of sensation. It is
sensation only that really exists, for that is a change that
we have experienced. Analogy leads us to conjecture,
according to certain indications, that similar changes
occur in all other animals, and, therefore, that there is a
property common in all these beings, which we call
sensibility. We see that in many cases these indications
become so transient that we are entitled to attribute
their apparent absence to the imperfection of our means
of observation.

With respect to motion, since it manifests itself
objectively, and this its manifestation is always induced
directly or indirectly by external causes, the distinction
between vegetable and animal motion has been sug-
gested to our minds, not by the action itself, but rather
by the quality of those beings hitherto regarded as plants
or animals on other grounds. And if we wish to find
elements of distinction in the phenomenon itself, we look
for them in the connection between external stimulants
and the motion produced, as also in the instruments by
which it is effected.. We endeavour to prove that in

352 ANIMAL NATURE OF DIATOMEE.

plants all movements are determined by the physical or
chemical influence of external agents. In animals, on
the other hand, the laws of inorganic nature are not suf-
ficient to explain the connection (otherwise more mediate
and remote) between the external impression and the
organic movement. Which distinction, besides being
relative to the degree of our knowledge, has, moreover,
a value limited entirely to the coarser phenomena, not
being applicable to those of nutrition and growth ; for all
these are accomplished by determinate movements that
cannot be explained by merely physical and chemical
laws. “ If nature,” exclaims Humboldt, “ had endowed
us with microscopic powers of sight, and if the integu-
ments of plants were transparent, the vegetable kingdom
would by no means present that aspect of immobility and
repose under which it appears to our senses.” And the
same may be said of the instruments; for the muscles of
higher animals very soon disappear when we examine
more simple or smaller animals, nor certainly can we
deny animality to those minute Infusoria in which we
are unable to distinguish either muscles or any other
distinct organs.

Having then ascertained the insufficiency of these two
principal characters, it became necessary to look for
others, not in the simple manifestations of a supposed
subjective property, but in the objective qualities them-
selves. And these not in their external form, for we
know not the limits of iZs variety, but in the internal
organisation, in the state of the more remote organic
elements, in their origin and formation, or in the chemical
materials of which they are constituted. This difficult
inquiry is assisted by recent discoveries, through which
science is now put in possession of a most important
truth,—that within the superior organic type, as well
in the vegetable as in the animal kingdom, there is
included, so to speak, in a summary manner, the history
of the lower, which present in a permanent form their
various intermediate states : that the same histological and

ANIMAL NATURE OF DIATOMEA. 353

morphological facts which appear manifest in the more '
simple organisms, are repeated in the more complicated ;
that the primitive organic structure is very similar in the
two kingdoms; in short, that in the first instance every
plant, every animal, and every tissue in the one or the
other, proceeds solely from cells. And since the primi-
tive state, which in superior beings is only transitory,
remains permanent in the inferior, we have thus, as well
in plants as in animals, very’ simple beings, reduced
indeed to the simplicity of a single cell. We do not
here inquire whether we have viscera, systems, tissues, on
the one hand, or roots, leaves, flowers, or even fronds or
spores, on the other; the difference we are endeavouring
to determine is in the primitive cell, that cell which
represents the ovum or the spore as transitory beings, or
the Protococcus and the Gregarina as permanent beings.
The field is open, and its boundaries are well defined.
The vegetable cell on one part, and the animal cell on
the other, but both alike in their first origin, in their
formation, in every successive change.

If a dangerous rock present itself here, and if we
cannot steer entirely clear of it, we ought at least to
point it out in order to prevent shipwreck. The means
by which we endeavour to augment the power of our
senses have a limit. ‘The microscope reveals the presence
of a corpuscle only the 100,000th of a millimetre in
size ; yet, since this corpuscle may be large in comparison
with those which entirely elude our vision, can we ever
boast that we are able to perceive the internal structure
even of larger bodies than this? Hence there is always
great danger of believing that to be simple which in
reality only seems to be so, and which the wonderful
artifice of organisation may conceal from our eyes by its
transparency, or by the compact nature of its parts.
Since the impossibility of penetrating deeper into struc-
ture is inherent in the means we resort to for the purpose,
we may still avail ourselves of comparison as a guide,

deducing nothing from observation beyond what is com-
23

354 ANIMAL NATURE OF DIATOMER.

parative. But the greater peril lies in the very nature of
the subject ; because two bodies, very different in degree
of organic simplieity, may appear very similar to each
other in our eyes, though armed with great magnifying
powers. And since we are now strictly endeavouring to
discover the characters of an element, which in respect
to us is more simple than any other, it is to be feared
that in some cases we may take some more complex
thing for a cell.

Every organic being, if observed at the first. instant of
its appearance, presents itself as a simple cell. When-
ever we have a cell before our eyes, this cell is either the
rudiment of an ulterior organism, or it is capable of
existing by itself and remaining permanently in the same
condition, or it is an elementary part of some organic
tissue from which it has been separated. Everything
anterior to the appearance of the cell, considered in its
general condition, may, in the actual state of our know-
ledge, be considered as still uncertain, or not fully
demonstrated ; and therefore it is that we take our
starting point from the already beautiful and well-formed
cell, because it is always identical in respect to its prin-
cipal characters. Its external coating solid, quite con-
tinuous, transparent, without any indication of particular
structure, viz., without a heterogeneous disposition of
molecules. The contained substance liquid, solid or
gaseous, different from what remains outside the cell.
Nucleus adhering to the inner surface, or detached within
the cavity. Nucleolus within the nucleus, distinct by a
different refraction of light or by colour, or by a different
appearance under chemical reagents. Another general
fact, common to all living cells, is an incessant mutual
interchange of materials between the fluid within and that
external to the cell, through the solid tegument of the
cell itself causing perpetual variations in the quantity
and quality of the former.

So far the conditions are common to the two or-
ganic kingdoms. We will now compare together such

ANIMAL NATURE OF DIATOME. 355

elementary or primordial cells taken from beings respecting
whose animal or vegetable nature there can be no doubt.
If both these be subjected to the action of chemical
reagents, they manifest different results; hence we are
led to conclude that there exists a difference in their
chemical composition.

It is useless to insist upon this mode of chemical
reasoning ; it may suffice here to quote the results of
chemical researches. The nucleus is composed of a
quarternary azotised substance (O. H. C. A.) ; this applies
equally to an animal and a vegetable cell. The solid
tegument, again, of the animal cell is always a com-
bination of proteine with water, ©. e. a quaternary azotised
substance also. (C.“ H.” O.? A); whilst that of the
vegetable cell always consists of an unazotised ternary
substance, isomeric with starch (C.* H.”0O.%). ‘The
contained liquid, also, is always ternary, unazotised in the
vegetable cell, quaternary and azotised in the animal. The
included solid substances are promiscuously ternary or
quaternary ; the former prevailing more in vegetables, the
latter in animals; and among the former, chlorophyll (?)
starch, and gum are found exclusively in the vegetable
cell. Chemical reagents, too, disclose an essential pecu-
liarity in the vegetable cell. An extremely fine, thin
membrane, granular in structure, of a quaternary azotised
composition, like that of the nucleus, lines the inner wall,
and hence immediately surrounds all the contents of the
cell, including the nucleus, with which, in most instances,
it is in direct continuity. This fine membrane is so thin,
and adheres so closely to the inner wall, that, in order to
perceive it, we must resort to physical or chemical agents
to detach it. It exists in every cell, and precedes the
formation of the wall; if it seem to be absent in any
case, the reason is that in most instances it soon
disappears.

These are positive facts; and in most instances the
experiments by which they are confirmed admit neither
contradiction nor doubt. But in the special case of a

356 ANIMAL NATURE OF DIATOMER.

cell respecting which we have to decide whether it belong
to one kingdom or the other, the chemical test is reduced
to data so precarious as not to afford the same certainty.
If the wall of a cell treated with iodine be, as well as the
nucleus, coloured brown, we may pronounce it to contain
azote, and to be formed of a quaternary material. If,
again, treated with sulphuric acid, and subsequently with
iodine, it assumes a violet colour, there can be no doubt
of its being isomeric with starch, since it has been changed
into that substance. But if these trials fail or prove
uncertain, as very often happens, we must of necessity
suspend our judgment. With respect to the contained
substance, besides the promiscuous character of some
materials already mentioned, some also which are exclu-
sive, as, for instance, chlorophyll or starch, may lead to
errors. ‘The stomachs of a Polygastric Infusorium may
be filled with these vegetable substances, and their
transparency and minute size may cause them to appear
very simple.

‘The successive changes in a cell furnish other very im-
pertant characters to distinguish the two kingdoms, but
give rise, at the same time, to new and grave difficulties.
Its extension, the excess of one diameter over the other,
the variety of forms it can assume, are frequent conditions.
The disappearance and reabsorption of the nucleus occur
in every cell at some period of its existence; but in the
cells of higher plants the fine inner membrane or primor-
dial utricle soon disappears. Here is a difficulty as to
distinction to be overcome. This remains permanent,
particularly in the Algze, if notin all inferior plants. The
enlargement of the wall, which in the animal cell takes place
in a homogeneous manner, is effected in the plant by the
deposition on its inner surface of successive strata, con-
tinuously or variously formed into circles, spiral bands, or
other intermediate forms, yet ofa ternary substance, and
varying little from that before mentioned (C.** H.* 0."),
These are produced at a much later period, and then only
in the cells form part of a complicated tissue. Then the

ANIMAL NATURE OF DIATOMEA. 357

wall is not only enlarged, but successively impregnated
with various substances, as lignine (C.” H. 0.5), with
carbonate of lime, with silica, or, finally, with a quaternary
azotised substance, as constantly happens in a portion of
the superior wall of the epidermal cells which forms thc
so-called cuticle, and in the thick cellular wall of marine
Conferve. ‘Thus the elongation effected in animal cells,
on their nuclei and on their nucleole passing into distinct
fibres, has only a remote counterpart in the liber cells of
plants, in the hypothalline tissue of Lichens, in the so called
seminal threads of Charee and Musci, and in some modifi-
cations of Kiitzing’s amylide cells. But these fibres,
so distinct in the superior animals, and in many of
the inferior, as in Sponges, for example, entirely elude
observation when we examine microscopic beings.

In animals, as well as in plants, new cells are
organised in the interior of their predecessors ; but in
vegetables the formation of the cells always seems to be
endogenous; in animals, on the other hand, it takes
place perhaps usually in the extra cellular fluid. The
multiplication of vegetable cells is proved to occur in
three modes.

1. Many nuclei appear floating together with granules
of a different nature. Around each of these collects a
minute vesicle, which successively increases, compress¢s
the whole of them, and, along with them, terminates by
filling the maternal cell, which, softening and liquefying,
is finally absorbed and disappears.

2. The internal substance of the cell divides into
two or four portions, which, from their origin, are seen
to be surrounded by a distinct primitive fine membrane
and each to be furnished with its respective nucleus,
whilst the primitive nucleus and membrane of the ma-
ternal cell disappear. And, consequently, only one or
two diaphragms divide the cavity among them, and,
by detaching themselves, constitute the walls of the new
cells.

3. In the third mode of cellular multiplication it is

358 ANIMAL NATURE OF DIATOMEE.

the wall itself of the maternal cell that, by inflecting itself
into an annular fold, constricts the fine primitive mem-
brane, which in such a case is persistent, and divides it
into two portions, so that on arriving at the centre, it
completes the diaphragm.

In the animals there have hitherto only been observed
with exactness the first two modes of endogenous forma-
tion of cells.

If now we descend from the comparative examination
of the vegetable and animal cell, considered generally, to
the special examination of the more simple organisms
among vegetables, excluding all those that can be con-
sidered of an ambiguous nature, we shall find almost
countless numbers which present in perfect clearness,
and in their primitive as well as in their permanent state,
the most simple condition of a cell and its successive
changes.

Among animals, on the other hand, we certainly have,
as a primordial and transitory state, the egg or ovum,
especially in the lower animals, which are very convenient
for observation ; but as representatives of their permanent
state reduced to its extreme simplicity, we possess solely
the genus Gregarina, of which we know six distinct
species, all of them Entozoa, all organised as simple cells,
but endowed at the same time with contractility and
expansibility quite sufficiently to put their animal nature
beyond doubt. For, when we consider the more simple
Infusoria, the Monades, the Vibriones, and Paramecia,
we soon perceive that their simplicity is apparent only.
In respect to these (Monades, &c.) we have not to take
merely account of properties inherent in a simple cell,
but must rather seek to estimate those which belong to
tissues whose organic elements escape our sight. Che-
mical reagents exert only a complex action upon the
entire material of the body, whence we suppose it to
be principally constituted of an azotised substance.
And here J dwell upon the peculiarities of such Infusoria ;
for if, on one hand, they denote an organisation far more

ANIMAL NATURE OF DIATOMER. 359

complicated than what was formerly ascribed to these,
they may, on the other, claim to represent the ordinary
conditions of the elementary cell.

Ehrenberg has described and delineated in many so-
called Polygastric Infusoria, a mouth and anus, many
vesicular stomachs, secerning glands representing the
masculine sex, and ovaries along with these, together
with one or more eyes in very many. The existence of
such organs, in certain species, seems to be a fact now
placed beyond controversy and beyond doubt. But the
criterion by which the organs themselves are judged by
analogy to exist in other microscopic beings, are not
equally certain. hus in the Closteria, and generally in
all the Desmidiez, it is clear that Ehrenberg is egregiously
mistaken.

He supposed to be a stomach the nucleus, which, in
Closteria, as in Zygnemata, is, from the first, suspended
in the middle of the cell, and is large, transparent and
colourless: but in order that these might systematically
be termed Polygastric Infusoria, he applied the names
of stomach and spermatic glands promiscuously to grains
of starch and gonidia in their different states of develop-
ment. Chlorophyll and all the rest of their contents he
arbitrarily represented as ovaries.

The introduction of a coloured substance, accomplished
only once in a Closterium, and only into one of the
vesicles situated at the two extremities, proves no more
than this, that the supposed terminal apertures may
really be found in certain species at certain periods of
their existence. And we know that in vegetable cells,
at certain periods, there are formed in certain parts of the
plant, circumscribed and regular apertures through
which the contents issue forth. The mere presence of
an aperture, and the introduction of exterior solid sub-
stances through this opening, cannot, therefore, be an
absolute character of animalıty ; for this, like other cha-
racters, is only of value as it is in accordance with the

360 ANIMAL NATURE OF DIATOMEX.

general conditions of organic beings. Having observed
the presence of eyes in Infusoria we forthwith proclaim
as eyes every red opaque spot, not merely in Infusorial
Animalcules but in all microscopic objects, and the pre-
sence of eyes is adduced as an incontestable proof of
their animal nature. The observations of Kiitzing,
already quoted, on the metamorphoses of Microglena
monadina into Ulothrix zonata, and of Cryptomonas
pulvisculus into Stigeoclonium stellare, clearly show that
elementary vegetables may not only manifest an appa-
rent movement but may also present a body similar to
the so-called eye in Infusoria, and the last is probably
nothing more than a cell-nucleus.

Finally the division into two equal parts, or as we
term it the deduplication, may take place in a being
of complex organisation in a mode apparently similar
to that by which it is effected in a simple cell. Not
only in the lower Infusoria, as Monades and Vibriones,
but in Polypi also, we see a transparent area appear first,
and subsequently a line of demarcation in the place
where a true division is effected at a later period.

Having premised these general considerations, let us
examine the Diatomex, availing ourselves of the special
and often cited labours of Ehrenberg and Kiitzing, as
well as of scattered observations by other authors, and
adding to these the result of our own researches.

Every Diatomean is formed of a siliceous shield and a
soft substance therein contained. According to Kützing,
this shield consists of pure silica, or, in some cases,
perhaps, of silica combined with alumina. Nägeli, further,
says that the silica is deposited in the outside of an
organic membrane, which he believes to be of a vegetable
nature. In fact, an organic membrane ought to exist,
for the silica could not become solid except by crys-
tallising or depositing itself on some pre-existing sub-
stance. On the other hand, we cannot admit, with
Nageli, that it has been deposited externally ; for in

ANIMAL NATURE OF DIATOME. 361

many genera, and especially in the Achnanthidia, the
siliceous shield is covered with a very delicate dilatable
membrane, itself containing silica, as is proved by its
sustaining unchanged the action of fire and acids. There-
fore, comparing this shield with other organic formations,
whether animal or vegetable, containing, in like manner,
either silica or some other so-called mineral element, we
may reasonably consider it to be formed of an organic
tissue permeated by silica. This permeation may occur
either in the wall of a simple cell, as is seen in the
epidermal cells of many plants, or within minute cells, as
in various plants and animals. ‘The action of heat or of
acid, in these cases, destroying the organic matter and
leaving the silica untouched, does not alter the ap-
parent form of the organ, because the skeleton remains
unaltered.

Externally to the shield, Kützing observed a thin
stratum, which he denominated cement, which may be
made visible either by desiccation or by calcination, and
produces either a simple opacity, or lines, points, and
maculz, sometimes irregularly disposed, sometimes regu-
larly. He supposes it to be a silicate of iron or of alumina.
Independently of the chemical materials which it may
contain, this outside integument seems to me the more
important inasmuch as even without resorting to the
means indicated by Kiitzing, I observe it to be constant,
not merely in the species enumerated by him, but also
in many others, and I could almost assert that it exists
in all. For to me it appears to correspond with that fine
membrane of the Achnanthidia above mentioned, which,
according to Kützing’s own observations, is always
visible whenever the two new individuals, (into which
every Diatomean is resolved in its multiplication by de-
duplication) (sdoppiamento) begin to separate. The
lines and points supposed to belong to the subjacent
shield belong very frequently to this kind of covering.

The shield itself is formed of at least four pieces, or
valves, united together in a four-sided figure—tetragon.

362 ANIMAL NATURE OF DIATOMER.

The mode of union is unknown. But the existence of
a kind of articulation which permits an opening and
closing, like the valves of a shell-fish, described by Corda
in a species of Swrirella, has been denied by other
observers. Be this as it may, whether spontaneous after
death, or induced by external means, this separation
does take place in a regular manner. Now, if we sup-
pose an organic cell with a wall permeated by silica, and
with a four-sided figure, we can easily suppose that all
the sides will mechanically support each other. More-
over, we shall meet with numerous facts by a different
kind of analogy, viz., that with solid animal tissues belong-
ing either to the internal skeleton or the external tegu-
ment.

The four valves are equal in length, but in many
species and genera one pair exceeds the opposite pair in
breadth. In order to establish an uniform language it is
convenient to term those primary valves or surfaces
which exhibit along the middle the line of division in
the act of deduplication, which, since it is formed here in a
normal manner, runs parallel to the other two surfaces,
denominated Zateral. Along the primary surfaces we
frequently see longitudinal lines, which terminate at the
two extremities in small apertures. From their internal
surface there project into the cavity linear marks vari-
ously formed but always longitudinal; these are termed
vitt@.

The lateral surfaces have frequently a round aperture,
of greater or smaller size, in the centre, and from this a
fissure extends towards each extremity. This fissure
either loses itself gradually, or expands into the regular
terminal apertures. When this occurs, each of these
surfaces is divided into two distinct valves. On these
lateral surfaces we observe the striz, lines, and trans-
verse costa, no less admirable for their beautiful appear-
ance than for their constant regularity in number,
direction, and proportion. When many individuals are
united together to form one compound being, like a polyp,

ANIMAL NATURE OF DIATOMER. 363

for instance, it is always by the /ateral surfaces that they
touch each other; and since all other characters some-
times fail, we can affix to them the denomination /ateral
from this principal one.

Besides the vitt® before mentioned, in some genera
(Biddulphia, Clemacosphenia, Terpsinoé) there are other
solid substances in their internal cavities; these are
variously arranged.

These essential peculiarities of the shield may perhaps
be regarded as indicating a complex structure, very
different, therefore, from what would be prescribed by a
simple cellular wall. Ehrenberg deduces from it an
argument to compare it with the shell of Mollusca.
The Arcelline may be cited among the Infusoria.
Kützing states, in reply, that among vegetable cells
there is found a peculiar conformation of the walls, with
prominences, depressions, points, lines, papille, and
perforations, disposed in a regular manner; he refers
to grains of pollen, as an instance. He might have
added the more appropriate instance of the Desmidiez,
which would be very closely allied to the Diatomez,
if the latter, like the former, could be referred to the
vegetable kingdom. If not equal in constancy and
regularity, the Desmidez display a greater degree of
complication; and we must remember the different
nature of their substance, for in the vegetable cell, when
lime or silica predominates, the wall becomes uniform and
regular (?) (im the text uniforme ed (rregolare.)

The soft internal substance is brownish yellow, or of
a gold colour. It is so described by Kützing. At first
it is almost always homogeneous; at a later period it be-
comes granular, and divides into lobes, or contracts into
many spherical bodies, or only into one larger globule.
The development, forms, and distribution vary in different
groups, but are characteristic in the greater number of
these. Usually at first there is formed a continuous
membrane, which afterwards splits longitudinally, and at

364 ANIMAL NATURE OF DIATOMEE.

a later period transversely, forming four lobes, which at
a later period divide into minor portions. Hence Kützing
infers that this substance corresponds with the gon:mzc
matter of Confervee and Algae in general. And he ad-
duces, as a principal argument, that by means of alcohol
he can extract from the Diatomez a colouring matter
similar to chlorophyll.

There exist, besides, among this substance, minute,
colourless, ane transparent spherical globules, varying, in
the same species, in number, size, and disposition, at
different stages, and we may add, according to various
conditions, even under the eye of the observer. Kützing
describes them as oil globules, because he saw them run
one into another, as well on the inside as the outside of
the shield. And he adds that these oil globules, in
appearance and position, exactly resemble grains of
starch in other Algz, for which they seem to be sub-
stitutes, as happens in the cotyledons of Crucifers.
The oil globules of Kützing are regarded by Ehrenberg
as glands representing the male sex, and the supposed
gonimic substance he thinks belongs entirely to the
ovaries.

Finally, among the various bodies which constitute the
internal substance of Diatomex, we have to mention
some globules (glodelli), more or less numerous, which
are found disposed either in transverse arches (archi),
round the median aperture of one lateral surface, but in
very few species. These Ehrenberg regarded as stomachs,
being led to that opinion by seeing them coloured with
indigo—an effect, however, that could only be produced
by keeping the Diatomez a long time in water laden with
this colouring matter, and often renewed. Kützing be-
heves this circumstance sufficient to show that they are not
to be deemed gastric sacs, but merely solid corpuscles,
which, being situate near an opening, exerted an especial
attraction upon the colouring matter. He makes no other
remark on their nature.

ANIMAL NATURE OF DIATOMEM. 365

Whilst unable to confirm or refute the opinions of
Ehrenberg, we seem to have observed facts sufficient to
disprove those of Kützing. First, besides the three sub-
stances or bodies of a different nature described by this
author (the gonimic matter, the oil globules, and the
presumed stomachs of Ehrenberg), we observe in all
species when examined alive, and in many after death, a
colourless substance, mostly extended in the form of a
membrane, and which seems to stand in continuity with
the remaining contents. Indeed Corda observed and
figured it, and Ehrenberg, as well as Kützing himself,
makes frequent mention of it in his descriptions. I
dare not assert anything as to the nature and functions
of this fine membrane; but I do assert, notwithstanding,
that in its appearance, in its form, and its behaviour
under the action of chemical reagents, it differs from the
thin membrane or primordial utricle of the vegetable
cell, to which it might be compared.

With respect to the so-called gonimic substance, its
identity with the endochrome of the Algze is not at all
proved. Its colour is different, and it is differently
coloured by chemical reagents. ‘The resemblance to it in
some instances, as in Melosira, in regard to conforma-
tion and successive alterations, is only insappearance. In
the endochrome of Alge the monogonimic substance
begins by presenting a granular appearance, then it be-
comes distinctly granulated, and changes into the poly-
gonimic substance so minutely described by Kiitzing.
But these changes do not occur in the coloured substance
of Diatomex. If we insist upon a parallel, we can only
compare it to the cryptogonomic (crittogonomica) sub-
stance of Byssoidia, Callithamnia, Grifithsie, and Poly-
siphoni@. It divides into parts, which successively un-
dergo ulterior division. And in regard to these changes,
we may observe that there is an essential distinction
between those that occur during life and those that take
place after death, the greater number happening in the
latter condition. And, during life, besides the changes

366 ANIMAL NATURE OF DIATOMEA.

detected on comparing individuals of the same species,
those which take place under direct observation merit
particular mention. The lobes described by Kützing are
seen to swell, and in some places to project and retract
successively.

The identity of this substance with endochrome is con-
tradicted by Kiitzing’s own experiments, which will be
found very exact, by any one who may repeat them.
These prove it to be very rich in nitrogen; it emits
ammonia copiously when decomposed by heat, and this
can only proceed from a substance abounding with it,
which such a decomposition compels to yield it up. Nor,
on the contrary, do I believe that there is any weight in
the argument from the solubility of its colouring principle
in alcohol, for this is not a property peculiar to chloro-
phyll or to any substance of vegetable origin. Finally, I
may add that if a portion of chlorophyll could be demon-
strated in the interior of Diatomex, this would by no
means invalidate their animal nature; we might still
suppose that they had swallowed it for food.

As to the oil globules, I fully agree with Kützing
that they have this appearance ; for some of them liquefy,
possess a high refractive power, and may be artificially
squeezed out, so to speak. Without any discussion of
the instances in which oily substances are met with in
vegetable cells, I argue that they are equally present in
the two kingdoms. For, I ask any one habituated to
the use of the microscope and to observations on In-
fusoria, whether the presence of globules of an oily ap-
pearance be not a constant fact, not merely in minute
animalcules, but in almost every portion of animal sub-
stance? The so-called Surcode of the French micro-
scopists assumes, in fact, the form of oil globules. I
observe, too, that the number and volume of these
globules increase considerably after death, and that
during life they are situated upon a longitudinal line
extending from one extremity to the other. And I rely
upon the observation that there is some motion and suc-

ANIMAL NATURE OF DIATOMER. 367

cessive alteration in them, as if these minute globules
mixed themselves with larger ones, and separated again
from them.

Finally, with reference to the supposed stomachs of
Ehrenberg, hitherto no fact enables me to satisfy myself.
I will only remark that, exactly in the median region of
Navicule, corresponding to the large aperture, the mem-
branous production before mentioned may be seen ex-
tended across, during life; and this, vanishing after
death, leaves in its stead an ample transparent area, of
circular figure, and surrounded by those granules that
take colour with indigo.

We will now continue the analysis of Kiitzing’s
anatomical and physiological observations. All the.
Diatomez, he says, give out through their apertures a
mucous substance, which he calls jelly, to identify it
with the vegetable jelly; this either diffuses itself in
water, or collects into various shapes, or contains entire
and determinate simple or multiple series of Navicule,
forming one or more gelatinous tubes, which, detached
or connected into bands, assume the form of the Phycoma
of true Alge. I confess that I have no arguments to
controvert the foregoing indication of the origin and
formation of the peduncles in Achnanthee, Gompho-
nemez, and Ulnariz; but to any one who has observed
these beings, the explanation will not be satisfactory at
all. It would be more probable to suppose that this
peduncle should represent the original cell within which
the siliceous frustules were successively developed. We
might again make this supposition in respect to the
gelatinous tubes containing the Navicule of Schizonema,
Micromega, and other allied genera. But be it a simple
product of secretion, or of itself an organic portion, this
substance may equally belong to an animal and to a
vegetable. Kützing declares it to be a gelatinous sub-
stance, or isomeric with starch; but adduces no experi-
ment to prove it. The trials I have made seem to indi-
cate a ternary non-azotised composition ; for when burned,

368 ANIMAL NATURE OF DIATOMER.

it has not the odour of horn, but of aniseed, and the
products of distillation have rather an acid than an alka-
line reaction.

According to Kützing, the propagation or multiplica-
tion of Diatomeze takes place in three modes; by deve-
lopment of the gonimic substance, by division, aud by
formations analogous to seeds or gemmules.

The first is merely suppositious, and therefore requires
no further notice.

Division is always longitudinal, and takes place under-
neath a fine external siliceous membrane, by the formation
of contiguous diaphragm-walls which divide the internal
cavity. ‘Thus the contents are longitudinally divided.
‚And this division is complete if the two new individuals
detach themselves, and so acquire individual liberty. It
is imperfect if the fine siliceous persistent membrane, and
the secreted gelatinous substance retain them collected
together. This mode of reproduction, (which Brebisson
distinguished by the name of duplication and deduplica-
tion from the reduplication of Desmidiez,) deserves the
most attentive observation. ‘The foregoing exposition
presents the fact in its most rude and superficial general
appearance, and makes us feel acutely the want of a more
circumstantial description peculiar to various forms. It
is only after having established facts relative at least to
the principal generic types, that we can establish, on a
scientific basis, the general idea of multiplication by dupli-
cation. A few observations suffice, however, to prove
that this does not occur in so simple a manner as we are
taught to believe by comparing it with that in vegetable
cells.

In the Achnanthidia, for example, it is described and
figured that the principal surfaces, which occupy the
intermediate space between the two superior and the
inferior valves, commence by presenting fine transverse
lines, and next a strong longitudinal line along the
middle; then there appear two new intermediate valves
contiguous to each other, the superior (valve?) of the

ANIMAL NATURE OF DIATOMRA. 369

new inferior individual, and the inferior one of the
superior. My observations convince me that the affair
does not proceed with so much simplicity. I have
often seen the two lateral valves separated, and the
intermediate space thus largely amplified. In other
cases there appeared only a new inferior valve com-
plementary to the superior, the inferior individual thus
remaining incomplete. Finally, in others, between
the complete superior individual and the incomplete
inferior valve, there appeared a new individual, with
both its valves; but nearer together, smaller, finer, with
lines much less distinct. The exact exposition of this
and other observations relating to it, will form the sub-
ject of another Memoir. It may suffice for me to inti-
mate here just enough to demonstrate, that in this phe-
nomenon there is more complication than that of a
simple cellular deduplication (sdoppiamento.)

The third mode of reproduction discovered by Kiitzing,
and that upon which he founds his principal argument
in support of the vegetable nature of Diatomez, is com-
parable, he says, to the formation of spores or of buds
(gemme) in plants. The Melosire consist of globular-
shaped individuals united together by means of a fine
external siliceous permanent membrane, into a filiform
series, in a manner perfectly similar to the articulations
of a Conferva. Each. of these consists of two principal
valves, in form like two sections of a sphere or polyhe-
dron, inserted upon a cylindrical wall, by means of
which the two valves or principal surfaces are united
together and continuous. Kiitzing saw some of these
presumed articulations to be dilated, as also occurs
in those which contain the spores of Cidogonia.
Though he observed nothing more, this was sufh-
cient for him to declare as a fact the propagation by
spores.

The other fact has reference to those Navicule which
have a simple or multiple sheath, constituted of what
he states to be a gelatinous substance consolidated into

24

370 ANIMAL NATURE OF DIATOMER.

the form of phycoma. In some species of Schizonema
and Micromega, he found contained within the same
substance, globular bodies, which he saw successively
enveloped in new phycoma, whilst the included sub-
stance, at first minutely granular, grew into so many
Navicule. The observation is valuable, and furnishes a
very important subject for study. For, whilst in other
cases the difficulty of keeping pace with the successive
development of the same individual obliges us to observe
comparatively, different individuals, in respect of which
there may always exist a doubt whether they really
belong to the same species, here we have, as it were,
a whole ércod, consisting of individuals which pre-
sent, at the same time, all the phases of their de-
velopment. And this expression of (covey or) brood
is not here used at random; since no direct argument
beyond that from external resemblance, tends to show
that these reproductive bodies are true spores; whilst,
in the animal kingdom we find equally numerous analo-
gies, as well in the ovaries of Polyps and other inferior
animals, as in many Ovipara of superior classes. And in
fact the bag ofa spider, with the thousands of small eggs
that it contains, seems to me quite as like as the spore
of an Alga to the organ of propagation of a Schizonema
or a Micromega.

Finally, in respect to the movements of Diatomez,
Kützing’s opinion evidently accords with ours; since,
after treating at some length on the question of their
animal or vegetable nature, he arrives at the singular
conclusion that Diatomez consist of three substances :
1, one imorganic, constituting the shield; 2, one
organic and vegetable, constituting the internal gonimic
substance, the external envelope, and the peduncles ;
3, one organic and animal, from which are formed the
organs of motion. We cannot admit this third opinion,
inasmuch as he assigns organs of motion even to the
lower vegetables and their spores, similar to those which,
according to him, partake of something like animal life.

ANIMAL NATURE OF DIATOMEA. 371

Ehrenberg discovered, in some Navicule, a distinct foot,
similar to that of Gasteropod molluscs, projecting from
the median aperture and from the fissure in the inferior
valve. In some Surirella, again, he observed extensible
and contractile cilia protruding and retracting through
numerous perforations in the margin. Certainly such
organs are not to be compared with the vibratile cilia
recently discovered on the surface of the vegetable beings
before mentioned. But (independently of the presence of
these organs, which hitherto have only been seen by
Ehrenberg and Corda) the motions of Diatomez, as
admirably described by Kützing himself, are so different
from the motion of Oscillatoriex, Desmidiez, Proto-
coccoidez, and the spores of other Algze, that they must
certainly be referred to a different origin. Careful experi-
ments may exclude all exterior causes, from the mediate
impulse of other bodies, from evaporation, chemical and
other agency. There still remains admissible the sup-
position of currents produced by the continued inter-
change between the exterior and interior liquid. But,
with equal right we may admit the other supposition,
that in a being whose nature, for other reasons, we
believe to be animal, the movements may be effected by
the admirable vital powers through organs which escape
our sight by their minuteness. I add that, even in the
smallest Navicule, observed with high magnifying
powers, there is seen, during their motions, an agitation
and a kind of sparkling, or, to speak more scientifically,
a rapid and indeterminate change in refraction of light at
their extremities, precisely in the situation of apertures
existing there in the shield. Hence I venture to infer
that though we cannot draw an absolute proof in support
of the animal nature of these beings from their move-
ments, it is still right to bestow particular attention on
these facts.

Resuming what has been hitherto said, and comparing
the arguments which seem to indicate the vegetable
nature of Diatomex with those which favour their animal

372 ANIMAL NATURE OF DIATOMER.

nature we are of necessity led to the latter opinion. If
we suppose them to be plants, we must admit every
frustule, every Navicula, to be a cell. We must suppose
this cell with walls penetrated by silica, developed within
another cell of a different nature, at least in every case
where there is a distinct peduncle or investing tube.
In this siliceous wall we must recognise a complication
certainly unequalled in the vegetable kingdom. It
would still remain to be proved that the eminently
nitrogenous internal substance corresponded with the
gonimic substance, and that the oil globules could take
the place of starch. The multiplication would be a
simple cellular deduplication (sdoppiamento), but it would
remain to be proved that it takes place, as ım other
vegetable cells, either by the formation of two distinct
primitive utricles, or by the introflection or constriction
of the wall itself. Finally, there would still remain un-
explained the external motions and the internal changes,
and we must prove Ehrenberg’s observations on the
exterior organs of motion to be false. But, again, ad-
mitting their animal nature, much would remain to be
investigated, both in their organic structure and their vital
functions; excepting this, so far as we know, we have
only one difficulty to overcome, that of the probably
ternary, non-azotised composition of the external gela-
tinous substance of the peduncles and investing tubes.
But as the presence of nitrogen is not a positive cha-
racter of animal nature, so the absence of it is not a
proof of vegetable. And in order that the objection should
really have some weight, it would be well to demonstrate
that this substance is isomeric with starch. For then,
supposing all the arguments in favour of the animal nature
of Diatomez were proved by new and more circumstantial
observations, this peculiarity, if it deserve the name of
objection, might still be regarded as an important dis-
covery. We should then have in the animal, as well as
in the vegetable kingdom, a ternary substance similar to
that forming the basis of the vegetable tissue.

ANIMAL NATURE OF DIATOMEA. 373

I conclude, however, that in the actual state of
science, the Diatomez are to be enumerated among
animals, but at the same time much remains to be
accomplished in order to disclose their intimate organi-
sation and vital phenomena. In the sadness of the re-
flection we are consoled by the saying of the immortal
author of ‘Cosmos,’ that there is a field open for great
discoveries where at present we see only scattered and
unconnected facts.

ORGANOGRAPHIC REVIEW

OF THE

GENERA OF DIATOMEA,

ESTABLISHED BY KUTZING.

1. Eptraymia.—Lorica in sectione transversali trape-
zoidea ; strie transversales valide interdum granulate v.
montliformes.

The characteristic trapezoidal figure of the transverse
section results from the circumstance that the two prin-
cipal surfaces are parallel to each other, whilst the lateral
ones, again, are more or less convergent.

The superior surface is convex, the inferior concave,
but usually with a much less decided curve; for which
reason they are not exactly parallel. In some species,
again, the inferior surface is plane, and the superior
strongly convex, and carried down to the lateral surface,
whence the section, instead of being trapezoidal, proves
semicircular. Besides, the superior surface, instead of
being regularly continuous, may present prominent lon-
gitudinal coste. At least this is the case in my
Epithemia costata, which occurs in Dalmatia, parasitic on
Biddulphie. (E. major e latere semielliptica apieibus
acutis non prominentibus, e facie elliptico elongata, dorso
longitudinaliter costata, costis ad latera transverse striatis.)
This species has the form of a grain of coffee applied by
its plane surface, and furrowed (solcato) longitudinally
along its convex surface. It is 0-043” long, 0'034”
broad, 0:017” high. And these longitudinal cost might
-perhaps indicate (accennare) an association of individuals,

ANIMAL NATURE OF DIATOMEA. 375

such as we have in the genus Himantidium, inasmuch as
the multiplication by bisection (dimezzamento) occurs
precisely in that direction. In such a case we should
have both in the genus Hpithemia and the Mimantidia,
incomplete division and lateral adhesion of individuals
in the family Eunotiee, and the first example of poly-
pariform association through adherence by one of the
primary surfaces, in this respect corresponding to
the Synedre, with this difference only, that the latter
adhere by one extremity. Ehrenberg observed four in-
dividuals thus connected in the Z. Westermanni. The
comparison is justified also by this, that in my Zpithemia
there appears a kind of foot, which projects at the two
extremities, with truncated appendages.

In all Epithemi@ the two principal surfaces present, at
each extremity, two small apertures, united to similar
apertures in the opposite extremity by fine longitudinal
lines. The transverse striae of the lateral surfaces are
very evident, and in some species (2. ocellata, E. Argus,)
terminate on the dorsum in round apertures. They are
furnished with cilia, according to Corda, in his Mavicula
ciliata, which to me appears to be an Hpithemia rather
than a Cocconema, as supposed by Ehrenberg (C. gzbdum).
The internal substance appears to be uniformly extended
at the origin, divided subsequently into two lateral
masses; it is brownish-yellow, or green. A series of
minute oily drops occupies the median line. Many
species live in fresh water, many in the sea, and some are
found in a fossil state. Kützing enumerates twenty-one
species, to which we think two others (EZ. costata, B.
eiliata,) ought to be added.

2. Eunotia.—‘ Lorica in sectione transversali trape-
zoidea, strie transversales tenuissime.”

Although the only character by which this genus is
distinguished from the preceding be the fineness of the
transverse strize on the lateral surfaces, yet the distinction

appears to be justified by the circumstance that the

376 ANIMAL NATURE OF DIATOMER.

Eunoti@ are never found adnate and parasitic, as is con-
stantly the case with the Zpithemie. They are all found
in fresh water, the greater number are exotic, many
rare. When observed laterally, they are frequently
seen to be more gibbous or prominent on the dorsum,
which proves that the prominences themselves are placed
transversely. Thirty-six species are enumerated by
Kiitzing. It would seem that he ought rather to refer
to the Zunotia formica than to the Zpithemia gibba, the
Eunotia No. 6 (pl. 2, fig. 27 ad,) of Bailey, which has
very well-marked transverse striz; and this uncertainty,
were there no other, renders the distinctive characters of
the two genera somewhat doubtful.

3. Himantipi1um.—Lorica in sectione transversali rec-
tangula; strie transversales tenuissima, densissime, in-
dividua in fasciam transversaliter et arcte conjuncta.

If we could distinguish the Himantidia from the
Eunotie by the incomplete division, from which there
result associations or polyparies in the form of a band,
as in Odontidia and Fragillarie, there would still remain
the character of the entire family, 2. e. the difference be-
tween the two primary surfaces. And since these asso-
ciations are not always numerous, as in the three typical
species (H. Soleirolii, H. Veneris, H. guyanense), we find
it to be justly remarked by Kützing, that this genus is
not yet well established, a remark that derives increased
value from the fact already stated, that there is a lateral
association even in the Zpithemie (Epithemia costata,
Men.). This very resemblance, however, attracts atten-
tion to another circumstance, viz. the parallelism in
the Aimantidia of the lateral surfaces, which, in the
Epithemie, are essentially convergent. Of the ten
known species, four only are European; they are all in-
habitants of fresh water.

Of the three genera now enumerated, Kiitzing consti-
tutes his family of Eunotiex, which only possess in com-
mon the single character of convexity in one and concavity

ANIMAL NATURE OF DIATOMER. 377

in the other, of the two principal surfaces; a character
which reappears in various genera of stomatic Diatomez.
Abstracting this character, the ZZimantidia would be
referable rather to the family of Fragillarieze, with which
they seem to have a greater affinity.

4. Mrripion.—Individua cuneiformia, prismatico-rec-
tangula, in corpuscula flabelliformia vel fascias spirales
arcte conjuncta. Strie transversales valida, pervie.

Kützing compares the Meridiez to the Gomphonemez,
which they really resemble, in the cuneate form of their
single frustules, when viewed in front. But Gompho-
nemez have a median aperture, and interrupted transverse
striae, on account of which they belong to another order.
In the order Astomatice, the author himself quotes the
Odontidia as allied to this genus; but the Synedre ap-
pear to me to approach it still more nearlv; from these
the Meridia in like manner rather differ in their cuneate
form—which is inconstant,—by their ovate obtuse figure
at the one and their acute figure at the other extremity
of the lateral surfaces. The observation of M. Zinckem
on the vitte, whose presence is inconstant, becomes
very important. This fact proves, in my opinion, that
there is no foundation in truly natural characters for the
primary distinction which Kiitzing establishes between
the vittated and the simply striated Diatomez, by which
so many natural affinities are openly transgressed, and so
many forced alliances are effected, as we shall soon per-
ceive. In the scanty state of our actual knowledge re-
specting the true organisation of these beings, it is im-
possible to establish a natural classification of them. In
order to deviate from this as little as possible, it would
be requisite to consider all the characters collectively, as
we do in all other beings, whether animal or vegetable.
And every distinction based upon a single character, be-
sides being purely systematic, loses all value as a facility
for classification so soon as exceptions occur, as in the
present instances. Kützing says that at first the internal

378 ANIMAL NATURE OF DIATOMER,

substance entirely lines the inner wall of the shell, it
becomes divided afterwards into minute portions, which
terminate by concentrating themselves in distinct globules.
I believe that these changes only occur after death.
Bailey succeeded in extracting a greenish resinous sub-
stance by means of alcohol. Only two well-defined
species inhabit the fresh water of all Europe; two others
are doubtful.

5. Eumeripion.—ZIndividua cunetformia, prismatico-
trapezoidea (?), in flabellum vel fasciam convolutam coalita,
demum stipitata. Strie transversales pervie, valide.

As Kützing has only seen dried specimens of the
Meridion constrictum of Ralfs, upon which he has con-
structed this genus, it seems that we may assert from the
exact description of this author, quoted at length by
Hassall, that there is no indication whatever of that
gelatinous pedicel like a cushion, upon which Kützing
asserts that the frustules are arranged in a fan-shape,
as in the Synedre. Perhaps this erroneous impres-
sion may be founded on Ralfs’ figure and descrip-
tion of the dried specimen, compared with the living
one. These are his graphic words :—“ As, however,
they are not arranged in a plane, as in Aeridion
circulare, but stand nearly erect, somewhat like the
staves of a tub which is broader above than below,
when they are dry and fall down they necessarily
separate, and gaps are produced in the circular outline.
In the dried specimens I find some of the frustules
arranged in a circle, which however exhibits the gaps
already noticed, whilst others seem to be fasciculated.”
Therefore there remain only the trapezoidal section from
the inclination of the lateral surfaces and the constriction
of these near the apex, which characters, though un-
doubtedly of value to discriminate species, are not sufli-
cient to establish a genus.

The superfluous division of genera, whilst it disguises
the true affinities of objects, and fruitlessly complicates

ANIMAL NATURE OF DIATOMEE. 379

the study of them, has the additional mischief of exalting,
in some degree, the value conventionally attached to
characters, and compels us to form a distinct family of
every genus. Such is the case with this attempt of
Kützing in respect to the last two genera with the name
of Meridiona, though they do not really differ from the
preceding genus Zunotia, or the following one Fragillaria,
except by a slight modification of form. Yet a similar
modification does not seem sufficient to distinguish
the two genera Meridion and Zumeridion. In general,
characters deduced from the form of single individuals,
certainly deserve a preference in comparison with those
furnished by associations of numerous individuals into
polypariform bands; but inasmuch as we do not know
the relation between outward figure and internal or-
ganisation, the subdivision of families founded only upon
this character seems premature, to say the least.

6. DenticuLa.—Lndividua libera singularia vel binatim
conjuncta, a latere primario oblonga lL. linearia, secondaria
transversim striata 1. costata ; stri@ pervie, valide.

The morphological character of this genus is the pre-
dominance of the primary surfaces over the secondary,
and the continuity of strize crossing these latter. We shall
have an opportunity of returning to this particular subject
when treating of Surirella. At present it is sufficient
to observe, that whilst the first five species described by
Kiitzing, and figured in plate 17 of his work, show the
greatest affinity, not merely one to another, but also with
the subsequent genus, the two others, D. constricta and
D. undulata, display only how vague is the artifice of
this system which brings together objects so dissimilar,
and separates those which are truly allied. In these two
species there is not only wanting the predominance of
the primary over the secondary surfaces, but instead of
transverse striz, there are elevated coste, and in one of
them (D. undulata) even vitte are visible, as they are in
Surirella solea, to which it bears so great a resemblance,

380 ANIMAL NATURE OF DIATOMEE.

and yet, notwithstanding all this, it is included in the
grand division of Diatomee non vittate. The name of
any section and the character whence it is derived, need
not be constant when the section itself is founded upon
an assemblage of other characters, and its true charac-
ters consequently derived from affinity. But when this
character is isolated, it entirely loses all the systematic
value it can possibly have, so soon as it is wanting in
constancy.

7. Opontipium.—ZJ/ndividua gquadrangula, a latere
secondario transversim striata, lanceolata, in fasciam
biconvezam arcte conjuncta.

The Odontidia are merely a filiform series of Denticule.
Whilst among the Zimantidia there are promiscuously
enumerated species of which the individuals are conca-
tenated, and species with individuals merely geminate
(H. Arcus), here, on the contrary, two genera are distin-
guished by this character solely. And the same character
—the cuneate form of the frustules—by which the genus
Meridion is distinguished from Himantidium, is again
met with in Odontidium, but inconstantly and irregularly.
1 do not wish to infer from this that these generic dis-
tinctions may not be appropriate, because in the paucity
of our knowledge respecting the intimate organisation of
these beings, there is no adequate support for this opinion
or the contrary ; but it seems to me a clear inference that
im an organological point of view these characters possess
little value. Then, the number of transverse striae varies in
the same species, probably according to age. Six spe-
cies inhabit fresh waters, principally alpine, one only (0.
syriacum) inhabits the sea, one (O? glans) is found
fossil, and one (Fragillaria grandis, Ehr.) is uncertain,
to which, as an uncertain species, we may add the Syrina
annulata of Corda, which, if the figure (‘ Alm. Carlsb.,’
1833, tab. iv, figs. 45, 46,) be correct, has the singular
character of continuity of the transverse strie even over
the primary surfaces.

ANIMAL NATURE OF DIATOMER. 381

8. Fracınuarıa. — Individua linearia lavissima sym-
metrice formata, in fascias vel rectas vel curvas, bicon-
vezas, arcte conjuncta.

The singular individuals which constitute the filiform
aggregations of Fragillarie, are so like Navicule that
there is often a doubt whether a particular species shonld
be referred to the Fragillarie or to the genus Diadesmis,
in which the filaments are formed of Navicule possessing
the essential character of a median aperture in the lateral
surfaces. In fact, this doubt pervades all the new species
enumerated by Ehrenberg and by Kiitzing, with a note
of interrogation, among the Fragillarie. Thus the absence
of transverse striz does not seem a constant character,
or at least it seems that it ought not to be considered
essential, inasmuch as some of these doubtful species
(F.? anceps, F.? amphiceras) are striated. And Bailey
describes and figures numerous and evident strize, even in
F. pectinalis, merely observing that “it requires a high
magnifying power and skilful management of the light
to render these apparent.” In this” genus, too, as well
as in the preceding one, and with a little more regularity,
we have frequently a cuneate form of frustule, resembling
that of Meridion. There is a highly important fact, in
an organographical point of view, presented by the
Fragillariea, in the variable length of the filaments as
compared with the invariable length of the frustules com-
posing it, a variation probably induced by age. In the
paucity of our positive knowledge respecting the succes-
sive development of these beings, we must take this fact
into consideration. The internal substance presents great
variety of distribution, as is shown by Kützing’s reducing
to F. pectinalis all the species on which Ehrenherg had
founded his character deduced from this substance. The
four species safely referred to this genus inhabit fresh
waters.

8 (bis). GRAMMATONEMA, a genus hitherto ill defined,
regarded by the author as intermediate between Fragil.
laria and Diatoma, and to which Kützing, besides the

382 ANIMAL NATURE OF DIATOMEA.

species of Agardh (@. striatula, G. Jurgensii), adds, in
his work on Bacillariz, three marine species of Fragillaria
enumerated by Harvey (/. diatomordes, Grev., F. aurea,
Carm., F. Carmichaelii, Grev.), though with respect to
the last, Harvey himself objects to its position. I am
much more satisfied with the other plan suggested by
Harvey, to place it in Striated/a, for as the vittae are well
marked in this genus, the species seem to belong to it.
Kiitzing himself, in the Phycologia Germanica, united
the two species (striatula and Jurgensii) of Agardh into
one corresponding with the Arthrodesmus striatulus of
Ehrenberg, changed the named Grammonema into Gram-
matonema, and referred this genus to the Desmidiex. As
to the Frag. diatomoides of Greville, with which I was
favoured by Harvey, I think this conclusion right. It is
a true Desmidiean, for it has no siliceous shield. And it
is to be observed, that how perfectly soever it may
resemble the Fragillarie in form, it wants the longitudinal
canals and terminal perforations of the primary surfaces ;
and the internal substance is similar to that of the
Desmidiee. But as to the Conferva striatula (E. B.),
Sowerby’s figure certainly represents a Diatomean.
Wallroth has favoured me with a specimen thus named,
collected by Jürgens, and it proves to be a Grammato-
phora. To the same genus, too, belongs the Diatoma
striatulum, supplied by Lenormand, whilst the Fragillaria
striatula, which I received from the same author, really
belongs to the genus Fragillaria, and corresponds per-
fectly with the &. virescens of Ralfs. So there remains
no small doubt in respect to this genus, which can only
be removed. by a comparison of original specimens.

9. Diaroma.—Individua (linearia) quadrangula, sym-
metrice formata, primum in fascias conjuncta, demum
soluta et per isthmum gelineum molle plus minusve dis-
tinctum angults concatenata.

The species with striated and perfectly linear frustules
(D. vulgare, 10. mesodon, D. tenue,) are precisely similar

ANIMAL NATURE OF DIATOMER. 383

to Odontidia ; and those with perfectly smooth frustules
(D. pectinale, D. vitreum, D. hyalinum,) to Fragillarie.
Therefore there remains no other character to distinguish
them except the angular connection into flexuose chains ;
this character appears again in other genera (Tabellaria,
Grammatophora, Rhabdonema,) of distant sections. We
shall hereafter have occasion to resume this subject. We
will only observe now, that this condition is always
associated with another, that of a peduncle by which the
chains are affixed to submerged objects. Perhaps it
happens more frequently and more remarkably than in
Odontidia and Fragillarie that we find in Diatoma the
cuneate form of frustules, and it is surprising to see
the inconstancy of the forms which Kiitzing, with in-
comparable diligence, has been able to collect, describe,
and figure, referring them to different species. Three
species (D. mesoleptum, D. elongatum, D. Ehrenbergii)
differ greatly from the others, being contracted in
the centre of the principal surfaces, and two of them
(D. elongatum, D. Ehrenbergii,) still more because they
are incrassato-capitate at the extremities of their lateral
surfaces. (In respect to the D. Hhrenbergii, Kützing
cites as synonymous my Glawonema Heufferi, because in
the specimen I sent him he saw only the Diatoma, which
is parasitic on the Gleonema, which he did not notice,
and so he made me appear to confound a Diatoma
with an Hydrurea. In the arbitrary selection he makes
of some characters from external form to separate
genera, families, and orders, we cannot help feeling sur-
prise in finding united in the same genus species which
present differences so marked. ‘I'he character of flexuose
concatenation, independently of organographic condition,
(which as we shall see is of little value, reappearing in
other groups,) ought to have much less systematic value
than those taken from the conditions of form, which may
be supposed to have a direct bearing upon internal
organisation. For my part I think it would be much
more natural to place the smooth species (D. pectinale,

384 ANIMAT, NATURE OF DIATOMEE.

D. vitreum, D. hyalinum,) in the genus Fragillaria ; those
striated with elliptico-lanceolate lateral surfaces ( Diatoma
vulgare, D. mesodon, D. tenue, D. mesoleptum,) in Odon-
tidium. There would remain, as distinctly generic,
the only two species which have capitate extremities on
their lateral surfaces, (D. elongatum, D. Hhrenbergii.)
These two proposed unions would be justified on both
sides, for whilst the Odontidia have forms little dif-
ferent from Diatome, the Diatome are little different
from Pragillarie. But I wish it to be well understood,
that it is not my object to propose changes in the nomen-
clature or systematic arrangement of Diatomez. I only
intend to institute an organographic examination of the
proposed genera and groups. And organographically
we shall probably have more important distinctions than
those of form between Diatome and the Fragillarie ;
the latter have constantly two apertures at each extremity
of the principal surfaces, which seem to be wanting in
Diatome, without adverting to the resemblance between
the Diatome tenue var. dimotum and the very singular
Bacillaria.

The character by which the last four genera (Denticula,
Odontidium, Fragillaria, Diatoma,) are collected together
into one family, namely Fragillarieze, is the conformity of
the two primary surfaces; nor do I know how the genus
Meridion is excluded, even by the minutest characters.
Kützing, indeed, cites the affinities with Himantidia
among Eunotiex, with Diadesmis among the Naviculee,
with the various genera of Striatellee and Tabellariez
among the Vittat®. The relation appears to us rather one
of analogy than of affinity, being the polypariform asso-
ciation of many individuals—conditions which associate
together almost every form; and by this rule Melosira
might be allied to Fragillaria. As to internal substance,
Kützing says it is originally uniform in the shield of all
Fragillariee, then divided into minute particles, mixed
with oily globules, or contracted into a spherical mass.

ANIMAL NATURE OF DIATOMER. 385

10. CrotLorrLLa.—Individua singularia vel binatim
conjuncta, disciformia ; latus primarium distinetum, an-
nuliforme ; latera secondaria plana. (Lorica bivalvis,
valvis planis, orbicularibus, annulo interstiali conjunctis.)

With this genus there commences a series of forms
which have a type totally different from the preceding.
In the former the two primary surfaces are always dis-
tinct, whilst in those under consideration they unite in a
continuous cylindrical superficies. In the one the lateral
surfaces have always one diameter larger than the other,
so that they become more or less Jengthened ; whilst in
the other they are flat and circular, or convex and con-
cave, but always segments of a sphere. In the preceding
series we have, indeed, among the Odontidia, the Fragil-
laria, and Diatome, such a convexity of the principal
surfaces as is almost round, but the extremities remain
always distinct; and in the lateral surfaces the striae
or any other processes run transversely without in-
terruption. Here, on the other hand, we have a very
evident radiated arrangement. This same arrangement
is presented in another “family (Coscinodisceze) of another
group; and there we shall have occasion to mention it
again. In the genus Cyc/otella we find species brought
together which in fact possess great similitude of external
form. But those from fresh water (C. operculata, C.
Meneghiniana,) are free from attachment, and surrounded
by a gelatinous substance; whilst the marine species
(C. scotica, C. ligustica, C. maxima,) are parasitic. But
if, again, we observe that the striz or radiating puncta of
the former are wanting in the latter, we shall find, in
that circumstance, reason to suspect that even in internal
organisation, to us entirely unknown, there may be very
remarkable differences. Hence the observations of Nagel,
on what he terms a new species of Gallionella, and
which certainly ought to be referred to this genus, are
very valuable. (See Henfrey’ s translation of Nageli’s
‘Memoir on Vegetable Cells,’ in Ray Society’s Reports,
1846, Tab. VI, figs. 1, 2,3; Tab. VII, figs. 27, 28.)

25

386 ANIMAL NATURE OF DIATOMRE.

Among Kützing’s species this could only be referred to
C. scotica, to which the author assigns a diameter of so”,
whilst Nägeli says that his species varies from 0'014’ —
0:027”; but not being able to decide without comparing
them together, it is better, to avoid confusion, that the
supposed Gallionella should be named Cyclotella Nägelit.
In this species, which he examined whilst hving, Nägeli
describes and figures a nucleus of colourless mucus
attached to the wall of one of the two lateral surfaces ;
from this, various colourless mucous threads extend them-
selves, (sap currents, as in the Spirogyre,) which run
along the wall itself, or more rarely into the cavity, one
of which, however, constantly goes across through the
axis of the cell, to the central point of the opposite over-
lying circular surface, where it forms a nucleus so soon
as there appears a diaphragm dividing the cavity itself
into two. This happens as well in individuals that have
no siliceous shield, as in those that possess one; for
Nägeli believes the shield to be external, and referable to
an extracellular substance. A similar appearance of
arachnoid threads radiating from a centre was seen, too,
by Kützing, in AZelosira salina. Globules of chlorophyll,
says Nägeli, are distributed in two circles near the obtuse
ends of the cylinder, or are disposed in rays round the
nuclei of the two circular surfaces. It cannot be denied
that such observations favour the vegetable nature of this
being, but certainly they cannot destroy the value of many
others that support the opposite opinion. In my Cyecl.
melosiroides, named by Kützing ©. ALeneghiniana, I observe
that the deduplication (sdoppiamento) constantly occurs in
individuals of smaller diameter, which on that account at-
tain a height proportionally and absolutely greater, that is,
a larger breadth of the interstitial ring. ‘The Euganean hills
afford a new species to this genus, in their thermal springs.

Cyclotella concentrica: C. margine in lateribus secun-
darus concentrie definito, radiatim striato. Diameter
varying from 0:008” to 0:02”, and the striated margin
occupies about half the radius.

ANIMAL NATURE OF DIATOMER. 387

Taking also intoaccountthetwodoubtful species (C. minu-
tula, C. Rotula), which Kützing justly suspects may be frus-
tules of Melosira, we have thus nine species in this genus.

11. Prxinpicuna.—Individua singularia vel binatim con-
Juncta, non concatenata, libera vel versilia ; latus prima-
rium obsoletum (nullum) latera secondaria conveaa. (Lorica
bivalvis, valvis converis, annulo interstiali destituto.)

It is really surprising that although Agardh, Kützing,
Ehrenberg, and Brebisson, have described and figured the
Cymbella or Frustulia operculata as the type of this
genus, and corresponding perfectly with the foregoing
generic character—Kützing himself, without acquainting
us with the mistake of others, or his own, should now
form the type of the preceding genus from this same
species, preserving the name at first proposed, but
altering the sense; and at the same time should describe,
as a new species of Pyzidicula, the P. operculata of Bailey,
which seems either identical with that of Ehrenberg, or
very similar to it, and to that formerly so described and
figured by the authors named above. ‘The fact is, that
the specimens of Brébisson and Leuormand, in my pos-
session, belong to Cyclotella, and not to Pyaidicula. The
other species (P. major) described and figured by Bailey
and Kiitzing, seems rightly to belong to the tribe of
areolated Diatomez. Of the species included in flints (P.
globata, P. prisca,) we can say nothing organographically,
so uncertain is their nature. The P. adriatica is a being
equally singular, of which we know nothing in an organo-
graphical and physical point of view. ‘The same may be said
of Ehrenberg’s two genera (Goniothecium, Rhizosolenia),
which Kützing places doubtfully at the end of Pyzidicule.

12. Popopiscus.—Individua singularia vel concate-
nata, stipitata ; latus primarium obsoletum (nullum) latera
secondaria convera. Stipes lateralis. (Lorica bivalvis,
stipitata valvis convewnis, subhemisphericis.)

The only species (P. jamaicensis) is too incompletely
known for anything positive to be inferred.

388 ANIMAL NATURE OF DIATOMER.

13. Poposıra.—Individua concatenata, distinctissime
stipitata, lorica ut in precedenti genere. Stipes cen-
tralis.

The Podosire are merely concatenated Pywidieule,
and this concatenation results from the persistence of the
fine external membrane within which the deduplication
(sdoppiamento) takes place, precisely as in the next genus,
in which examples are not wanting of an uniting isthmus
and peduncle, by which the NMelosire also sometimes
become stipitate. To the two species of Kützing (P.
hormoides, P. Montaynei,) both exotic, we can add one
from the Adriatic :

Podosira adriatica: P. articulis sphericis, viv de-
pressis. Sig. Stalio found it in Dalmatia, parasitic upon
Callithamnion Borreri. The articulations are in trans-
verse diameter, which is the longer 0-046’, in longi-
tudinal diameter 0:04”, or a little more, and frequently
the two diameters are equal, and the form perfectly
spherical. Though not differmg from P. hormoides,
except in the lesser depression of the articulations, I still
consider it different because of the constancy of that
character. Kützing, to whom I sent it, suspects it to be
the same as in P. hormoides. For my part I hesitated a
long time whether! should not refer it to a form of J/elosira
monoliformis, since in the Melosire, even, the interstitial
ring is at first absent ; but besides that I have found its
absence in very numerous specimens to be absolute, I
found nothing that I could refer to the annular channels
of the Melosire. Every articulation is constituted of two
valves, perfectly hemispherical, which separate on being
pressed; and each pair is contained in a cylindrical
sheath, which embraces and surrounds the contiguous
halves of the two articulations. This sheath has a re-
markable firmness, for when the articulations are - broken
or separated, it remains wide open and unaltered in
figure. It is crossed transversely by fine strie, eight of
which are contained in 0:0075”. 'Ihey are for med of as
many series 6f minute points, projecting like papille. It

ANIMAL NATURE OF DIATOMER. 389

often happens that the two articulations are separated a
little from each other, and the external tube is then con-
tracted in the intermediate space, perhaps indicating the
origin of the isthmus. I never succeeded in observing
more pairs connected together. ‘The stipes is little
inferior in length to the diameter of the articulation.
Longitudinal folds are always present, which I believe to
be six, since there are always four (at least ?) on each sur-
face. I have never succeeded in obtaining a sight of
that central aperture in the lateral surfaces, from which
Kützing says he has seen the stipes to issue both in Podo-
sire and Melosire, especially the marine species. Finally,
I observe that within the articulation there appears an
open space, which is entirely owing to the internal sub-
stance, for it is destroyed wholly by fire or acids.

14. Metosrra—ZJndividua concatenata,adnata. Lorica
bivalvis, valve cingulo v. annulo interstitiali tenerrimo
maxime hyalino conjuncte.

«<* Lysigonium.— Articulis globosis vel ellipticis, prope
utrumgue finem carina annuliformi instructis.”

“** Gallionella— Articulis cylindricis, non carinatis.”

The Melosire in general may be regarded as poly-
pariform associations of Cyclotelle, and the comparison
prevails principally in the second sub-genus. ‘I'he dis-
tinction of the two sub-genera is also proposed by Hassall
(Spherophora, Meloseira), but it is to Kützing we are
indebted for establishing it upon the important character
of the carina, which occurs only in the first two species
(M. salina, M. nummuloides), a character on whose
organographic value we cannot decide anything, but
which merits some consideration in a morphological
point of view. For that projecting ring bounds the lateral
surfaces ; whilst in the other species, with sides more or
less convex, these are continuous, as it were, with the
primary surfaces. In all the species we may notice
the double furrow which forms a ring connecting the
body of each individual laterally to the interstitial ring ;

390 ANIMAL NATURE OF DIATOMER.

this furrow or canal presents apertures disposed in a
regular manner. Kützing believes these supposed aper-
tures to be sections of the canals themselves, that is,
portions of them seen in projection. This opinion is the
only one consistent with the fact, that the filament being
cylindrical, and therefore presenting itself indifferently on
every side, these apparent apertures are always seen
arranged near the margin. Ehrenberg’s assertion that
they are more numerous in some species, does not seem
to be confirmed. ‘This appearance is still more compli-
cated, inasmuch as these fine tubular canals project from
the internal surface of the shield, and a slight furrow
externally corresponds with them. This condition is
evident in A/elosira distans, in which, owing to the
greater depth of the furrow, the apparent perforations
remain separated from the margin. The interstitial ring
presents peculiarities of which we have no instance in the
preceding genera. Its tenuity and the great variety of its
extension are important characters. But here we must add
the very important one of the changes it undergoes during
observation. It is not uncommon to see the two halves of
the articulation separate themselves slowly, and enlarge at
the same time with the rmg. This fact is not decisive in
respect to the great question of the animal nature of
these beings; for it is not subject to a subsequent con-
traction, and because in plants we have the analogy of
Spirogyre, in which, on the rupture of the outer tube,
the extremities of the articulation, which were inflected
like the finger of a glove, expand themselves as if by
elasticity; but many facts controvert this inference. In
support of the opposite opinion, is the frequent enlarge-
ment of a particular articulation, in a manner similar to that
of the Gdogonia. But Hassall justly observes, “for this
endochrome .... never becomes condensed into a dis-
tinct organ or sporangium;”... for this reason, the
resemblance is reduced to a mere appearance. As to
this supposed endochrome, proofs are certainly wanting
that it 1s an ovary, as Ehrenberg supposes ; but they are

ANIMAL NATURE OF DIATOMEA. 391

also wanting to show that it consists of gum, starch, or
chlorophyli, which would be necessary were it a gonimic
substance, as advanced by Kiitzing ; ; and analogy even is
wanting, for we do not see, in any Alga, a similar dis-
position of the internal substance. The often quoted
reseinblance to the Confervee cannot even be deemed
apparent; for in no Confervee are distinct spherules met
so regularly, or disposed so symmetrically. During desic-
cation it happens in the marine species, as in the Podosire
already described, that the internal substance adheres to
the inner wall in the form of oily globules surrounded
by a distinct, transparent margin, and compressed one
against another in the form of regular polygons. Ehren-
berg also speaks of diaphanous vesicular spaces, which he
regards as stomachs. Kützing enumerates, figures and
describes nineteen species, marine, freshwater, and fossil,
besides the four doubtful ones placed at the end, and the
famous ferruginea (M. ochracea, Ralfs,) which he proves
not to belong to the class of Diatomez.

We have a new species in the Euganean thermal
springs; this is so different from all the others, that it
might serve as the type of a separate genus, which,
meanwhile, I propose as a subgenus, with the name of
Pleurosira ; articulis cylindricis non carinatis isthmo
laterali angulatim concatenatis. The specific description
will be as follows -—Melosira (Pleurosira) thermalis: major,
articulis cylindricis solitiariis, isthmo laterali angulatim
concatenatis, disco laterali levissimo. Hab. inter Clado-
phoras et Lyngbyas in thermis Bugmeis temp. + 30 R.

The diameter varies from ;3, to „; of a millimetre (5 to
8 centomillimetres). The length of the articulations is so
variable, that I did not think it proper to mention it
in the description. The shortest scarcely exceed the
diameter, but others are twice or thrice as long. In the
smaller specimens the interstitial ring exceeds a little in
breadth the two lateral circular bands which form part of
the secondary surfaces. A distinct and large circular

canal, evidently projecting into the internal cavity, and,

392 ANIMAL NATURE OF DIATOMER.

corresponding to an external furrow, bounds the ring itself
on both sides, and is easily discernible, also, from the
diminished thickness of the wall. Where this ring is
most dilated, it presents two fine circular striae, which
divide it into three bands, the central one being the
narrowest. In the longer articulations this central band
is as broad as the others, or broader, and finally there
appears a third circular line, and a corresponding dia-
phragm, which divides it. The wall of the two bands
resulting from the division of the central one, grows
thicker, and these become similar in every respect to the
lateral valves of the two contiguous articulations. But
no sooner are the two articulations complete, than they
detach themselves from one another, and nothing remains
to connect them but a lateral isthmus, in appearance like
a joint (forme apparente de cerniera) (hinge), as in
Diatome and Grammatophore. The internal substance,
in dried specimens, is in the form of spherules, adhering
tenaciously to the internal wall of the secondary surfaces ;
and one row only of these spherules adheres also to the
interstitial ring by the side of the canal, in a similar
manner to the teeth of the AZ. sulcata. Only whilst the
two articulations are being completed, these globules are
found in the intermediate space. On one occasion I
have seen an articulation inflated as in JZ. varians. ‘he
isthmus is indistinctly unilateral and alternate.

At first sight of this singular Diatomean, the mind
instantly recurs to the figure of the Odontelle ; and this
resemblance is more strongly suggested by the figure
given by Bailey of his Gallionella, (pl. 11, fig. 8,) which
Kützing refers to Odontella polymorpha, a figure which,
except for the contraction corresponding with the circular
canals, coincides perfectly with our species. Were it
only that Bailey, when comparing his Gadlionella with
Diatoma auritum, insists upon its cylindrical form, its
want of appendages, and the mode of connecting the
articulations by a “flexible hinge-like ligament,” I
believe that Bailey might with justice regard his species

ANIMAL NATURE OF DIATOMEE. 393

as belonging to Gallionella or Melosira, and I propose
to name it Melosira (Pleurosira) Baileyi.

The celebrated Kützing, to whom I communicated
these remarks, replies, “ your Melosira (Pleurosira) ther-
malis is in no respect different from the Odontella poly-
morpha. I have compared your specimen with that of
Montagne. ‘There are even found the delicate (zarten)
points upon the shield, as in the other which I have
imadvertently omitted in my figure. Your specimen is
certainly an Odontella, although the ron sn. are
cylindrical (feretes), for it is the same also in the O. aurita.
I think of uniting, in future, the Biddulphiez with the
‘T'ripodiscieze.””

Although I have had an opportunity of examining
fragments only of Montagne’s Isthmea polymorpha, ad-
hering to an imperfect specimen of Polysiphonia subti-
lissima from Cayenne, with which the celebrated author
favoured me, I am still positive in treating the matter
differently. It is admirably figured by Kützing; the
articulations are not cylindrical, and though obtuse and
slightly prominent, the lateral processes are very evident.
Whether this belongs to the same genus as other Odon-
Zelle, and whether that genus belongs to the family of
Biddulphiez, and to the order Areolatz, is a question to
which we shall return.

Now, resuming all that has reference to the family of
Melosireze, we shall find, as a character common to them
all, the circular figure of the vertical section parallel to
the lateral surfaces ; a character which, as well as the
other, of a radiated disposition of the strie upon the
lateral surfaces, we shall find repeated in the family of
Coscinodisceze, which, having the shield of a cellular struc-
ture, belong to the tribe of Areolate. Perhaps we may
suspect some Melosire (sulcata, decussata, lirata,) to be
furnished with the same organic condition, and hence
arises & fresh doubt respecting the systematic value that
has been ascribed to it.

In general we may also say, that in the Melosirez the

394 ANIMAL NATURE OF DIATOMEE.

development of the lateral surfaces prevails over that of
the primary ones, which we find finally to disappear in
certain genera (Pyeidicula, Podosira,) as well as in some
species of Melosira (varians, orichalcea), the increased
length of the articulations involving the corresponding
development of the primary surfaces. And it is to be
observed, that although in this family the primary sur-
faces differ precisely as much in form as they do in the
three pregeding ones, yet we find in these the same
organic character as in the greater number of the other
genera, viz., the presence of longitudinal furrows or
canals. The separation of one lateral surface or valve
from the other, with the consequent dilatation of super-
ficies, which the primary surfaces exhibit before the du-
plication takes place (though verified to some degree in
other genera, yet in the AZe/osire better than elsewhere),
presents an undeniable analogy with the reduplication of
Desmidiex, which Brébisson distinguishes from the de-
duplication of Diatomex. ‘The particular disposition of
the internal substance, the currents or mucous threads
radiating from a centre, the enlargement of some arti-
culations, and the dilatation of the interstitial ring, are
isolated facts, which however merit particular attention
in the paucity of our knowledge.

15. Campytopiscus.—Individua singularia, discifor-
mia; discus curvatus vel tortuosus, rotundato-ellipticus
radıatus.

Although I have hitherto only been able to examine
that one species of this.genus (C. clypeus,) which is
found in the fossil flour of Santa Fiore, ın the kieselguhr
of Franzensbad, and constitutes the entire substance of
the tripoli of Eger, I think I can add something to
what Kützing says of it. He indicates, indeed, in
fig. 5, the thickness of the margin, which, in this in-
stance, represents the primary surfaces uniting together
into a continuous superficies, but neither in the other
figures nor in the description does he notice it any

ANIMAL NATURE OF DIATOMER. 395

more. Now, this superficies merits the more considera-
tion because, referring it, as analogy requires, to the
primary surfaces, it offers an exception to the general
law that the transverse strie are wanting. For these are
very evidently continuous, and therefore may be com-
pared to those upon the lateral or secondary surfaces of
Denticula, of Odontidium, and Diatoma. We noticed
the same condition before, treating of Odontidium, in the
Syrine annulata of Corda. But there remains that other
character of the primary surfaces which seems to have
the more organic importance,—the longitudinal division.

I have not seen the intermediate gradations, but I
have certainly seen two individuals, one superimposed
upon the other, and adhering closely, which might fairly
be regarded as proceeding from the deduplication (sdop-
piamento) of one individual. This brings new support to
the affinity of this genus with the Melosire suggested by
Kützing. That microscopical observations are to be
interpreted with the severe scrupulosity of critical logic
is well known to those who habitually use that valuable
instrument; and the prudent caution will be more re-
quisite when we have before us a fact at variance with
many others. I ought not, therefore, to suppress a
doubt that occurred to me relative to the continuity of
these transverse strie over the primary surfaces. In
hundreds of individuals I have succeeded in obtaining a
front view of the margin, and in seeing it crossed by
those thick strie which correspond to the radii of the
lateral surfaces. These are among the microscopic ob-
jects which may be regarded as gigantic, and in respect
to which we may banish all suspicion of illusion. But
it may be supposed that in all such cases I have had
before me only one of the lateral valves, and that the in-
terstitial ring was wanting. Individuals geminate through
an antecedent deduplication might have removed that
doubt.’ But these are rare, and owing to the complica-
tion produced by the superposition of four similar trans-
parent valves, I could not safely decide whether the striae

396 ANIMAL NATURE OF DIATOMER.

were continued through the entire depth of a cylinder
which I could only see obliquely or in front.

As to the interruption of the radii, which is regarded
as a specific character, this is not at all constant, and
may, perhaps, depend upon the imperfect state of the
specimens. ‘The dotted appearance of the central disc
always presents that regularity which Kiitzing only
represented in the fig. 5 before mentioned. Similar puncta
may also be seen in the spaces between the radii. The
central aperture described by Ehrenberg is rightly denied
by Kützing. A sort of analogy in form connects this
genus with some species of the next; the only distinc-
tion I believe to be a repetition of that very important
character of transverse striee on the primary surfaces.

16. Surırzına.—Individua singularia navicularia,
margine striata; latus secundarium primario majus, linea
media longitudinali levi percursum.

This genus is divided into four distinct sections. The
first comprises the flexuose species, (S. elypeus, S. Cam-
pilodiscus, 8. flecuosa, S. elegans, S. spiralis, S. Myodon) ;
and really one is at a loss to find the motive that could
induce Kiitzing to separate these generically from Cam-
pylodisct. In fact there only remains, in my opinion,
the above-mentioned character of strie continued over the
primary surfaces in Campylodiscus clypeus to distinguish
that genus. But the doubt already expressed as to this
character, acquires still greater weight when we compare
these Campylodisei with the flexuose Surirelle.

In the 8. Campylodiscus Kützing represents (Pl. xxviii,
fig. 26, c, d,) the lateral valves detached, which give a
perfect figure of a Campylodiscus, and their inclined
margins viewed in front (a, 6,) resemble transverse strize
on the primary surfaces.

The species (S. didyma, S. solea, 8. regula, 8. multi-
fasciata, S. thermalis,) narrower in the centre than at
the extremities of their lateral surfaces (medio plerumque
constriele) are, in the opinion of Kützing himself, so

ANIMAL NATURE OF DIATOMEZ. 397

allied to the Synedre, that there remains no character to
distinguish them except that they are free, whilst the
latter are parasitic and affixed.

I confess that I cannot comprehend by what motive
Kiitzing divides the numerous species that follow into
two sections, (oblong, ellipticee et ovate.) Were there
a difference, how small soever, but constant, this might
have a systematic value as rendering the distinction of
species more easy ; but we have only to compare together
the two species craticula and bifrons, which figure in
the two sections, to convince ourselves that the distinction
proposed is not based on a constant character. And it
causes real surprise to find enumerated in the second of
these sections a species (S. angusta), which it is true has
not the median contraction, but, from similitude of form,
would by any one be supposed to belong to the section
preceding, which we say is allied to the Synedre, and in
which section we have the S. regula and WS. multifasciata
both equally wanting in that character. Comprising,
then, ina single group, both these sections, we assert
that here exists that important character of the secondary
surfaces exceeding the primary, which, as before stated,
forms the contrast with the Denticule. But even among
the latter there is not wanting an instance of the opposite
condition (D. undulata.) The new Surirella Jenneri, of
Hassall, as well as Denticula constricta, has the primary
surfaces perfectly equal in dimension and form to the
secondary. After all I believe that affinities and dis-
tinctions are rather to be sought in internal organisation
than in external form, the latter having no organogra-
phical value except as an indication of the former. With
regard to structure, though we are still far from having
sufficient data whereon to establish any principle of
classification, yet we find in Suriredla, more, perhaps, than
in any other genus of Diatomez, a multiplicity of organs
and a complex organisation. The 8. striatula, of which
Turpin and Corda have given figures of little accuracy
and in a great degree imaginary, supplied to Ehrenberg

398 ANIMAL NATURE OF DIATOMER.

materials for numerous and valuable observations. It
would appear that Kützing, anxious to establish the
vegetable nature of Diatomez, designedly passed over
this argument, and sought to distract attention by creating
new species out of the various forms assumed by 8. sérza-
tula at successive periods of age and degrees of de-
velopment. Such we may suspect to be his 8. Pala
and & ovata, as well as the S. ovalis of Brebisson, who,
as early as 1835, and not in 1838, had made public his
S. biseriata, a name, therefore, which ought to be
retained in preference to the later one (S. bifrons) of
Ehrenberg. Bailey, too, noted the quick and lively move-
ments of &. striatula, and I had frequent opportunities of
observing it im our Euganean warm springs. I could
compare together living individuals, among which there
occurs an indescribable complication of internal structure,
and dead skeletons, such as are represented by Kützing.
Nor can I omit here the 8. gemma, in which Ehrenberg
discovered numerous extensible and contractile cirrhi
which appeared to serve as organs of motion. It appears
that Kützing had seen something similar in S. solea,
(Pl. ii, fig. 61, 2a.) And in regard to S. gemma we
must remember the lateral openings from which, accord-
ing to Ehrenberg these cirrhi are protruded ; openings
which it would seem must exist also in S. fastuosa, and
which remind us, also, of those before mentioned in some
species of Apithemia, as the cirrhi remind us of the cilia
of #. ciliata (Navicula) of Corda. It appears to me
that it is now with Diatomes as it was with Mollusca
down to the time of Cuvier, and that anatomy has to
effect the same beneficial revolution in their natural
classification, which it produced in the system and
nomenclature of Conchylia.

Kützing finally ascribes to the same genus Surirella,
as the last section or sub-genus (Podocystis), that species
which I found to be so common in our sea, and which
he therefore names adriatica; this association is truly
singular, for whilst we see that the second sections are

ANIMAL NATURE OF DIATOMER. 399

merely distinguished from Synedre because they are not
affixed, we find the Podocystide stipitate and _ affixed.
Yet do I intend to maintain that it is not allied to the
other Surirelle. I only notice how vacillating are the
principles of the proposed classification. The Podos-
phenia of Hassall, excluding the synonyms, seems to
belong to this sub-genus.

17. BacıLnarıa. —Individua bacilliformia prismatico-
rectangula, linearia, primum in seriem rectam tabulatam
transversim conjuncta, dein in series obliquas dimota.

The singular appearances assumed by the only species
of this genus (B. paradoxa) and the liveliness of its
motions have long been celebrated (Müller). The prin-
cipal organographical character that distinguishes it from
the Fragillarie is the same that allies it to a different
group of the family, viz., the interruption of the trans-
verse strie in the median line of the secondary surfaces,
to which is added the parallelism of the primary surfaces.
Hassall overlooked the former of these characters in the
figure he gave of this species. The physiological cha-
racter of mobility of the frustules, and the symmetrical
disposition which they assume, becomes the more im-
portant, inasmuch as they do not recur in any other
Diatomez ; and therefore we believe that they merit this
particular mention.

18. Synepra.—ZIndividua bacillaria, prismatico-rec-
tangula, demum uno vel altero fine adnata; latus secun-
darium primario equale, vel angustius, linea levissima
media longitudinali percursum.

* Scaphularia— Minute, rarissime adnate, levissime;
(non transversim striate.)

The eleven species enumerated in this sub-genus are
only classed together by negative characters, viz., the
want of the characters of other genera more or less allied.
In general it is only required that they should have their
secondary surfaces marked with transverse striz, either

400 ANIMAL NATURE OF DIATOMEA.

continued or interrupted, to be placed among the Den-
ticule or the Surirelle. In one (8. quadrangula) we
have the character of Denticule, the excess of the pri-
mary surface over the secondary; in others (S. virginalis,
S. constricta,) we have the median contraction of the
primary surfaces characteristic of the second section of
Surirelle. Thus, indeed, all these species only want the
central aperture to belong to the Navieule or Ach-
nanthidia (S. Biasollettiana). Certainly we cannot say
that the presence or absence of these characters is of
little importance ; we have only to remark that with the
highest powers of the microscope it is often impossible to
decide with certainty whether they have the transverse
strie and the median aperture or not.

** Eehinaria: levissime, demum afive et plerumque
radiatım aggregate.

The seventeen species contained in this section do not
differ materially from those in the former, except in being
affixed. Many of them are attenuated at the extremities
of their primary surfaces; but those destitute of that
character ($. amphicephala, S. tenuissima, 8. tenuis,)
have great analogy in form with the Ulnarie. We have
also species in this section that are curved in their
secondary surfaces (S. curvula, S. Arcus,) and in their
primary ones, (S. /unaris, S. bilunaris,) which resemble
the Zunotie and Achnanthidia. The S. amphicephala
is distinguished from all by its dilated extremities.

*** Olnaria: afiee, flabellatim disrupte, in latere
secundario, excepto spatio medio longitudinali levi, trans-
versim striate.

Although the twenty-four species of this section have
nothing in common but the general character of all the
Öynedre (their bacillary form and the absence of a
median aperture), still we find enumerated among them
species that are unattached, (armoricana, sigmoidea,
vermicularts,) and even destitute of the characteristic strize
(vermicularis); and this because the spirit of system (spirita

ANIMAL NATURE OF DIATOMER. 401

systematico) has not gone the length of separating them
from the other species with which in all other respects they
have superior affinity. And as to the transverse strie,
this character of their interruption at the median line,
which is not only stated in the definition of the section
and of the genus, but is even taken for the basis of
classification in the primary division of Diatomee non
vittate astomatice, clearly fails in very many species,
(premorsa, aequalis, mesolepta, Ulna, danica, splendens,
armoricana, sigmoidea, scalaris,) in which these stric are
continuous, as in Denticule. The D. oblonga may be
compared with the above-named species. And it is also
to be remarked, that though the transverse strie are
continuous in these species, as Kiitzing has accurately
delineated them, still the characteristic transparent median
line remains visible when the object is withdrawn to the
remotest extremity of the microscope, which proves that
there must be a longitudinal furrow traversing all the
strie; and to ascertain its depth it would require that
the screw regulating the movement of the stage or of the
microscope should be micrometric. This slight furrow is
also visible in a fragment that accidentally presents the
transverse section of such a Synedra. The type of this
section is 8. Ulna, and many other species as well as this
(acuta, oxyrhyncus, amphirhynchus, valens, armoricana,
sigmoidea, vermicularis,) have the primary surfaces per-
fectly linear; but others, again, have the extremities of
these surfaces attenuated (dedilis), like the greater part
of those of the preceding section ; others only rotundate,
(premorsa, spectabilis, scalaris ;) in reverse of these
many are contracted in the middle, and cuneate and
truncate at the extremities, (Janceolata, mesolepta, aequalis,
vitrea, danica, splendens, biceps, capitata.) Among the
latter we have three, (danica, biceps, capitata,) which, in
the important character of capitate extremities of the
secondary surfaces, resemble the amphicephala of the
preceding section. And in the greater number of species
in this section, as well as in some comprised in the
26

402 ANIMAL NATURE OF DIATOMEA.

former, (notata, Martensiana, Vaucherie,) the form is so
similar to that of Navicule as to leave nothing but the
want of central aperture to distinguish-them. “Finally,
there are not wanting in this section species more or less
curved. ‘Those that are curved in the secondary surfaces
(mesolepta, biceps,) might be regarded as similar to
Eunoti@, but they differ essentially in being attached.
Those again which are curved in the primary surfaces
(Ulna, tergestina, armoricana, sigmoidea, vermiculans,)
have analogy only with the Achnanthee. As to the
Sigma, Kützing himself avows his suspicion that it may
belong to the Raphidogloee.

**E* Tabularia ; bacillis in stipite brevi, horizontaliter
crescente, tabulatim disruptis.

Exclusive of two (S. Gallionii, S. Arcus,) all the spe-
cies (9) of this section want the transverse strie ; and all
have that linear form, slightly attenuated at the ex-
tremities of the primary surfaces, which we have noticed
in many species of the preceding section. The distinctive
character of this section, the stipes on which the frustules
grow side by side contiguous to each other, is very im-
portant in an organographical point of view. And by
this character the species described and figured by
Hassall under the name of $. dunaris would seem to
be related to the S. Arcus, if it be really distinct.

**EE® Grullatoria ; stipite elongato sepe ramoso, ba-
cillis plerumque geminatis levibus.

Among the six species of this section, which in their
aspect call strongly to mind the family of Licmophorez,
two are perfectly linear on the primary surfaces, ($,
erystallina, 8. gigantea,) and one of them ( gigantea) has
the extremities of the secondary surfaces capitate. The
rest have the primary surfaces attenuato-truncate at the
extremities. All are smooth, wanting strie.

ANIMAL NATURE OF DIATOMEA. 403

RR Pimaria ; bacillis in tabulam connatis, demum
modo Diatomatis disruptis et angulis alternis coherentibus.

Besides the sectional character which intimates an
analogy with Diatoma, the only species that figures here
(S. rumpens) differs from all the other Synedre by the
tumid and rounded extremities of the primary surfaces.

From this rapid examination of the sections into which
the seventy species of Synedre are divided, and to which
Kiitzing adds seven more as uncertain, it appears that
very different relations might be established among them;
and that if in the greater portion an evident similitude
in form would seem to indicate a very distinct genus, in
many there appear indications of resemblance to genera
and families totally different. We must therefore repeat,
in this instance, that in the want of data whereby to
judge of the organic importance of character, and in
the arbitrary nature of the selection, of necessity resulting,
Kützing has achieved a supremely laborious and diligent
task, by discriminating, describing, figuring with won-
derful accuracy, and distributing with some sort (gua-
cungue) of systematic order so immense a number of
species. As to the organographical considerations which
can be instituted in this genus, they reduce themselves
to the single one of length predominating over breadth,
and the eminently bacillary form derived from it. Thus
Kützing observed the opposite characters of Synedr@ and
Surirelle ; that the lateral surfaces exceeded in one, the
primary surfaces again in the other. But it is not in this
that the opposition really exists. For even among the
Surirelle we have some (medio plerumque constricte) of
those which do not exhibit the boasted prevalence of the
lateral surfaces, and which, therefore, we might with
equal propriety enumerate among the Synedre ; whilst
almost all Synedre of the first section (Scaphularia), and
some of the second (Zehinaria) want even the last dis-
tinctive character that would remain,—of being affixed.
‘The surfaces, which in all Syzedre are really reduced to
the smallest dimensions, are the two which in Surirelle

404 ANIMAL NATURE OF DIATOMER.

of the last two sections, (oblonge, ovate, elliptice,) and
in the sub-genus Podocystis, still remain very evident,
viz., the terminal surfaces. Kützing observes, that in
conformity with the flattened form of the Swrirelle, and
the lengthened form of the Synxedre, the intermediate
spaces are placed laterally on the median line of the first,
and are accumulated at the extremities of the second.
But this accumulation never occurs until after death.
Whilst they are alive the internal colouring substance is
mostly situated along the median line of the lateral sur-
faces, or sometimes along the sides of these, and then in
four to eight distinct lobes. In some species it is dis-
posed in symmetrical and equidistant transverse fascize. In
the central region there is often a transparent space, and
many other varieties are met with; these are quite suf-
ficient to indicate a complicated organisation, but we do
not know how to interpret them rightly. Finally, we
ought not to pass over in silence the important organic
condition of two very distinct longitudinal lines on each
of the primary surfaces, terminated at both extremities in
minute perforations; a condition clearly delineated by
Kützing in seventeen species, and which, in the smaller
ones, we may suppose to have been obscure, or even
unobserved.

Comparing together the four genera (Campylodiscus,
Surirella, Bacıllaria, Synedra,) which constitute the
family of Surirelleze, it is easily perceived that the last
two only deviate from the Fragillariese by the character of
interrupted strie ; and the first two deviating sensibly in
the succession of species from the circular shape of the
lateral surfaces, or of the transverse section, establish a
transition between the Melosirez, and the group formed
of these two genera, along with the Fragillarieze and the
Meridiee. Hence it is impossible to establish an organo-
graphical character that shall embrace the entire family
and strictly represent its type. For even restricting the
organographical data we possess to the predominance of
the vertical surfaces (primary and secondary), with the

ANIMAL NATURE OF DIATOMEM. 405

greatest reduction of the terminal ones (inferior and
superior), such as we have in the Fragillariee and the
Meridiez, but without the predominance of the primary
over the lateral, as in the former,—what value these
characters have, in what relation they may stand to
internal organisation, I do not believe that we can decide
in the actual state of science.

The five families (Hunotiee, Meridiee, Fragillariee,
Melosiree, Surirellee,) united together and arranged in
two groups, as they have the striz continuous (the first
three), or interrupted (the last two), constitute the order
Astomatica, or those wanting a character that is regarded
as essential to the following order.

19. Cocconzis.—Individua singularia elliptica, de-
pressa, latere secundario foraminifero adnata, nunquam
stipitata, latere superiori medio longitudinaliter impresso-
sulcato.

The general form of Cocconeis is that of a disk of an
ellipsoidal figure, with surfaces more or less_ exactly
parallel, plane, or slightly curved. It corresponds, there-
fore, to the figure of Campylodiscus and the flexuose
Surirelle ; for in this genus, as in those, the secondary
surfaces prevail so much that the primary are reduced to
a simple margin. We know these to be the secondary
surfaces by the transverse or radiating strisee with which
the superior surface in many species is marked, and by
the central perforation of the inferior surface; and
because the division which is effected parallel to these
corresponds to the marginal fascia which represents the
primary surfaces. Contrary to all the genera hitherto
examined, it is precisely by one of these secondary sur-
faces that the Cocconeis adheres to those filiform alge,
on which it lives parasitically. Hence their resemblance
to the Epithemie is only in appearance. The individuals
multiplied by duplication become quickly free, for it is
rare to find them geminate; but they soon adhere
parasitically to Algze, and collect together in great mul-

406 ANIMAL NATURE OF DIATOMER.

titudes. Most of the freshwater species are perfectly
smooth. Jt is remarkable that the form of C. Pediculus
(C. Kützinge, Breb.) is conico-truncate; this is not noticed
by Kützing in his definition, much less in the figure, on
which account, before asking for his opinion of my own
specimens, I thought he was describing a different species.
Hence, in the duplication, the superior individual becomes
smaller than the inferior; and from the same condition
it results, that the margin appears bilineate when it
is simple, as Kiitzing figures it, and trilineate as the
same Kiitzing describes it in the specific definition,
when it is merely in the course of duplication. The
marine species display on their superior surface very
elegant transverse granulated strie, which either extend
across the entire breadth without interruption, or radiate
either from a median line or a central space. In only a
few species the strize are longitudinal, or concentric and
waved (flexuose). The ulterior characters by which the
thirty-four species of this most elegant genus are distin-
guished one from another, are still very slight.

20. DorypHora.—Lorica simplex bivalvis quadrangula
navicularis non concatenata, apertura in latere secundario
nulla ; linea suturali media longitudinal ; stipitata.

The principal characters of the family are wanting in
the single species of this genus (D. amphiceros.) Fixed
at one of its extremities by a stipes, and wanting the
central aperture in the secondary surfaces, it differs from
the Surirelle only by the continuity of the transverse
strie. In respect to the central aperture, Kützing
observes, that it may even be wanting in the Navicule
themselves, and may be wanting in some individuals
though present in others of the same species. On a
character like this is based the difference of the orders.
With more right, and supported by numerous facts, I
can assert that there is a continuity of the strie in many
Surirelle. ence I regard the Doryphora as allied to
these, and particularly to the Podocystide.

ANIMAL NATURE OF DIATOMEA. 407

Now with regard to the family of Cocconidez I can
only repeat what has been said of the genus Cocconeis,
that it presents a new type of organisation, differing
from the preceding, summarily, in this, that the temno-
genesis is effected transversely in the direction of the
body, though vertically in respect to the point of attach-
ment ; in other words, that in these the surfaces become
superior and inferior, which in the others were lateral.

21. Acunanruipium.—Jndividua simplicia, singularia
vel binata, libera ; a latere primario linearia genuflexa.

Admitting it to be proved that in the species of this
genus (4. microcephalum, A. delicatulum) there positively
exists a median aperture in one of the lateral surfaces
and not in the other, and that two perforations exist
at the extremities of the primary surfaces, as stated in the
definition of the order and in that of the family : admit-
ing this, we should still have to decide whether the un-
certain relations of these characters to other families,
and their inconstancy, will give us any right to erect a
distinct genus on principles so slight and precarious.
This is, indeed, a systematic experiment that is not
sufficiently established on an organographical basis.

22. AcHNantHES.—Jndividua solitaria vel binata vel
numerosa in fascias plus minusve elongatas transversaliter
conjuncta, stipite laterali adnata.

In the want of striz three species (minutissima, exilis,
parvula,) present great analogy of form with the pre-
ceding. In one of these (parvula) there is wanting the
characteristic angular bending, for which reason it be-
comes very similar to Odontidium and Diadesmis. The
other ten species (striate) differ only by very slight
characters from each other. Besides the organic differ-
ence between the two secondary surfaces, the constant
median aperture of the inferior or ventral, (Ehrenberg,)
and besides the process of duplication, which may be
studied, in all its details, in the Achnanthides better than

408 ANIMAL NATURE OF DIATOMEA.

in any other Diatomez, the stipes truly merits particular
consideration. Its constant collocation proves that the
Achnanthides are, like the Surirelle, adherent by one
extremity, and the insertion of the stipes becomes oblique
only because the duplication always takes place on the
side of the dorsum ; that is, in other words, from the two
individuals which are formed at the expense of the first
one, only the one corresponding to the dorsal surface is
ultimately separated; and the same thing occurs with
those that follow. As to the internal substance, Ehren-
berg says it is divided into many rounded portions,
which in A. longipes collect in the middle, like rays,
around the median aperture. In the A. salina (A. bre-
vipes, Ehr.) the same Ehrenberg describes this substance
as separated, from the first, into four lobes, which
finally divide and resolve themselves into moveable cor-
puscles.

23. CrmBosina.—Zlndividua vel solitaria vel binata,
stipitata ; in series isthmo gelineo concatenato.

The essential character by which the single species
(C. Agardhii) generally differs from the Achnanthides
seems to indicate that in this the duplication happens
promiscuously either in the inferior individual or the
superior. ‘The series consisting of solitary individuals
may be considered as originating from the successive
duplication of only one superior or dorsal individual.
The same may be supposed of the series of geminate
individuals alternately conjoined; but when the’ con-
junction is unilateral the supposition is admissible that
after the first duplication is accomplished the second is
effected in an inferior individual, and repeated in the
inferior one through the successive links of the chain.
We may notice that the dimensions vary greatly in
different individuals, but are constantly the same through
all of one series. ‘The specimens from Cayenne, para-
sitic on Polysiphonia subtilissima, (along with Podosyra
Montagnei and Odontella polymorpha,) differ from the

ANIMAL NATURE OF DIATOMEE. 409

Adriatic specimens by their larger curvature and more
decided transverse strie.

The family of Achnanthez is also distinguished from
all others by the complicated structure of the shield.
The primary surfaces, Kützing says, are formed of three
pieces, two lateral, transversely striated, and one median
traversed by two longitudinal striee with terminal per.
forations corresponding to their extremities. Hence
every individual will appear to be formed of eight valves.
To me it appears, on the contrary, that these transversely
striated lateral portions can by no means be distin-
guished from the secondary surfaces ; there being neither
angle nor joint to indicate the supposed distinction.
I do indeed find that the two halves of each lateral
surface are inclined to each other like a roof, and they
easily become detached one from the other, thus con-
stituting, together with the two primary surfaces, at
least in appearance, six valves. The internal funnel.
shaped appendage which accompanies the central per.
foration of the inferior valve, is really very remarkable.

24. CymBerLa.—Individua solitaria vel geminata,
libera (nec adnata nec inclusa), curvata inequilatera ;
latere primario uno (interiori ventrali) angustiore, altero
(exteriore, dorsali,) latiore; lateribus secundariis equalibus
(transversim striatis) ; aperturis mediis marginalibus ap-
proximatis.

In general form, in the parellelism of the curved
primary surfaces, in the inclination of the secondary
surfaces, in the trapezoidal transverse section, and m the
mode of attachment when parasitic, (C. Pediculus,) the
Cymbelle are very similar to the Epitheme. They
differ essentially from these by the two perforations
placed in the border of the inferior side of the lateral
surfaces, and therefore sufficiently near each other to
seem united into one when placed obliquely. They have,
moreover, a distinct aperture at each extremity. The
difficulty of making out these characteristic perforations

410 ANIMAL NATURE OF DIATOMER.

in the minuter species renders uncertain the generic
arrangement of some among the fifteen species enu-
merated by Kützing.

25. Cocconema.—ZIndividua ut in genere prece-
denti sed stipitata, stipite ex uno apice cymbellarum
erescente.

Without concerning ourselves with the generic value
of the character which is wanting in six of the eleven
species ascribed to Cocconeme, it is most interesting to
consider that whilst some Cymbelle adhere parasitically
to submerged bodies by their ventral surfaces, like Zpe-
theme, the Cocconeme, again, adhere with a stipes by
one of their extremities. Are we hence to infer that the
adhering side may be either one of the primary surfaces
or one of the secondary (Cocconoidez) or finally one of
the extremities? Or must we regard adhesion as a
primary character in judging of the organographical
correspondence of the various surfaces and different
types, and make other characters subordinate to it, such
as the one derived from the division which sometimes
takes place in the direction of that surface, sometimes
transversely to it? Again, admitting the first case, ought
we not, at least, to ascribe to this character a value
superior to that of the presence or absence (at least when
they are doubtful,) of the central and terminal apertures ?
Or, finally, that adhesion of the only species of Cymbella
which is said to be parasitic (C. pediculus), is it not merely
ventral in appearance, as seems sometimes to be the case
in certain Achnanthides ?

26. Sınoreuıa. —Individua cymbelliformia transversim
in fascias circulariter in curvas connata, in substantia
gelinea molli amorpha nidulantibus.

The genus Syneyclia (8. salpa, S. quarternaria) repre-
sents, among the Oymbellex, the genus Zumeridion in
the order Astomatice, the Zpithemia costata in the
family of Eunotiee. Whenever the lateral surfaces are

ANIMAL NATURE OF DIATOMEA. 411

inclined to each other, by the different extension of the
two primary surfaces, the associated series must be formed
circularly, as it is effected in a circular or at least a -
curved manner in the plane of the associated series, when-
ever the primary surfaces are cuneate, and the con-
vergence of the lateral surfaces is in the direction of one
extremity (Meridion, Odontidium, Diatoma.)

27. Encyonema.—Cymbelle longitudinaliter seriate
tubo gelineo simplici tenerrimo molli incluse.

The gelatinous tube within which the Cymbellse
referred to this genus are included (Z. paradorum, FE.
prostratum,) might perhaps be compared to the stipes of
Cocconema, and thus serve to explain its orig. We
must, in that case, suppose the stipes to represent the
gelatinous sac within which the Cymbellz is developed.

In all the family of Cymbellese (Cymbella, Cocconema,
Syncyclia, Encyonema,) we may repeat what has been
said before of the genus Cymbella, since the distinction
of genera is based upon characters merely accessory.
We may here refer to what Kiitzing says of the internal
substance. This is disposed in two lamine extended
upon the lateral surfaces, which present a median notch
(emarginatura) corresponding to the convex side, and
are collected together into a very fine transverse mem-
brane.

28. SPHENELLA.—Individua solitaria, cuneata, libera,
nec afixa, nec stipitata, involuta.

The Sphenelle only differ from Mavicule in their
cuneate form, perfectly similar to that of Meridion, by
which, too, the associations ($. angustata) become flabel-
liform and quasi circular; but they differ from Meridion
by the central perforation of both secondary surfaces,
and by the interruption of the transverse strize of the
same surfaces, (S. glacialis, S. vulgaris.) Hence there
remains a greater similitude to the Navicule, and the
distinctive characters are so slight, that the generic

412 ANIMAL NATURE OF DIATOMEA.

arrangement of at least two species (S.? parvula, 8. ?
Lenormandii,) out of the seven remains uncertain.

29. GompHonemA.—Corpuscula silicea a latere pri-
mario cuneata, basi affix vel stipitata, stipite gelineo.

As Cocconeme from Cymbelle, so Gomphoneme only
differ from Sphenelle by the stipes; on which account
species are now referred to Gomphonema which formerly
belonged to Sphenella (@. olivaceum). And with respect
to the whole thirty-three species of Gomphonema, it is
still doubtful whether they ought not rather to be placed
among the Sphenelle. Independently, therefore, of the
value which the presence of the stipes may have as a
generic character, it is important to consider it in an
organographical point of view. Kützing supposes the
Gomphoneme to be at first free, like Sphenelle, and that
afterwards they affıx themselves by means of the (gela-
tinous) substance of the stipes, which in his opinion they
secrete from the inferior extremity. No direct observa-
tion confirms this hypothesis, and it is at least as just to
admit the other, that the Sphenell® are at first attached,
like the Gomphoneme, and afterwards become free.
Ehrenberg says, that the Gomphoneme can become free
and again adhere. The circumstance of a tubular cavity
through which this stipes runs, according to Kiitzing,
and the laceration that is produced in this tube, when in
the act of duplication the two new individuals separate
from each other, effecting a dichotomy, if by any means
it could be reconciled with the idea of a simple secretion,
certainly agrees better with the supposition that the
stipes in Gomphonema, like that of Cocconema, may be
compared with the tube of Zncyonema, and, like that,
capable of its own proper growth, and therefore endued
with life. But it remains to be proved that the stipes
can divide itself from above downwards, to produce the
dichotomy, as maintained by Kiitzing. ‘There is little to
be remarked on the form of Gomphonema. ‘The primary
surfaces are constantly cuneiform-truncate, In one only

ANIMAL NATURE OF DIATOMEE. 413

(eurvatum) they are curved. The secondary are obovato-
acute in the first eleven species; elliptico-lanceolate in four,
(dichotomum, affine, intricatum, lanceolatum;) in all the rest
they are distinctly capitate or more or less panduriform.

30. SpHEnosira.—Individua in filum complanatum
anceps rectum arcte conjuncta, a latere secundario apicibus
inequalibus ; apertura media distincta.

Kützing himself observes, that the single species of
this genus (S. catena) belongs rather to the genus
Diadesmis of the following family, because, although the
apices of the secondary surfaces are unequal, it wants the
constant character of all Gomphonemez, the cuneiform
primary surfaces ; whilst we see represented the associated
form of Sphenella angustata.

The Gomphonemee, according to Kützing, (Sphenella,
Gomphonema, Sphenosira,) are related to the Licmo-
phorez in form and development. ‘They differ by the
absence of the vitte, and the presence of a central per-
foration in the lateral surfaces. The internal substance
is disposed in two laminz extended over the primary
surfaces ; in opposition, therefore, to what takes place in
the preceding family of Cymbellee. Ehrenberg notices,
also, colourless vesicular spaces. We must not omit,
that even in Gomphonemex the primary surfaces are
traversed by the usual two longitudinal striz, terminating,
superiorly at least, in distinct’ apertures.

31. Navicuta.—IJndividua singularia libera, regu-
laria, rectangula, prismatica ; apertura media rotunda.

In this genus, the richest of all in species, and the
type of a family the richest of all in genera, from which
some have adopted the name Naviculee rather than that
of Diatomez for the entire class, the constant character
is the symmetry of each pair of surfaces as well as of both
extremities. We have seen this character, with a few
exceptions, in the family of Fragillariew, and still more
in the Surirellee. Hence it follows, that in some genera

414 ANIMAL NATURE OF DIATOMEA.

(Denticula, Synedra,) or in some species (Surirella) of
these we must resort to other characters to establish the
distinction, more especially as the forms are frequently
very similar. This essential character—that of the entire
family—is the presence of a central aperture in both the
secondary surfaces. But this character is wanting in some
species of Navicula (Oxyphyllum, vulpina, &c.) and in one
of the subsequent genera; and Kiitzing observes that it
is often very difficult to discover the aperture on account
of its minuteness, and that it is absent in some, though
evident in others of the same species. Therefore, without
attempting from this to argue in opposition to the
organographical importance of the character itself, it is
certainly of diminished value systematically considered ;
and Kützing acted prudently, in doubtful cases, by
regarding evident affinities of figure, so as not to separate
similar objects from one another. Kützing divides the
large number of species (137) into six groups, according
to their shape ;—/anceolata, oblonge 1. elliptice, gibbe,
constricte s. nodose, lunate, sigmoidee. The greater
number of species belonging to the first section (/anceo-
late) have precisely the form termed navicular, the
primary surfaces lmear, and the secondary longato-
elliptical, with their apices more or less acute. We have
seen above that the first section of Synedr@ (Scaphularia)
have this same form ; and after the admission of Kützing
himself and his example in respect to one species, it is
truly surprising to see the Scaphularie and Navicule
lanceolate generically separated from each other. Some
of the species referred to this first section show a gradual
transition to the different forms of the succeeding sec-
tions. But in all these we find species described and
figured in Kützing’s work so similar to one another, that
there occurs a well-grounded suspicion respecting the
propriety of the distinction. And here it is proper to
observe, that in Diatomez, more perhaps than in any
other class of organised beings, it is difficult to pronounce
a certain decision on the value of characters. In animals,

ANIMAL NATURE OF DIATOMBA. 415

as well as in plants, the multiplication by reproduction
is accompanied frequently by alterations more or less
important in size and external form. When, again, the
multiplication is effected by simple division, both the
forms and dimensions remain constant. Nor will we here
enter upon the difficult question that relates to reproduc-
tion; neither do we intend to define in what this differs
from simple division, though a division it certainly is. In
the Diatomez the distinction is easy. In these a repro-
duction certainly takes place, since mixed among the
larger individuals of every species we often see some
smaller, some very small, and others of every intermediate
size. But their enormous abundance seems to proceed
from division (divisione) rather than doubling (dimezza-
mento). Now, in doubling (dimezzamento), the forms
and dimensions (of the secondary surfaces) continue per-
fectly equal. Hence that wonderful uniformity in myriads
of individuals which present themselves to our observation,
all of which, perhaps, were derived by successive partition
from a single one. Hence the natural tendency that
must be felt by every observer to distinguish more spe-
cies when, among these individuals mathematically equal
to one another, he sees some rather different in form and
dimension; or when he sees other thousands of indi-
viduals differing only by slight conditions from the
former, but all precisely equal one to another. If, again,
he then happen to meet with forms mingled among
them, different but in degree, and which successive ob-
servation proves to belong to the same species, he reflects
upon the difference that prevails among them, as well in
proportion as in dimension, and he easily believes, again,
that these differences are really greater than those fre-
quently proposed to distinguish species. Kützing, for
example, gives us four figures of Navicula viridula,
(Pl. im, fig. 44; 1, 2,3, 5,6: Pl.iv, fig.10, 15: Pl. xxx,
fig. 37.) These he properly refers to the same species,
although the proportion between the breadth and length,
the degree of convergence of the sides, and the ventral

416 ANIMAL NATURE OF DIATOME..

prominence, are certainly unequal. If we compare the
three figures of Navicula nodosa (Pl. iu, fig. 57; 1, 2, 3,)
we shall see in one of these (2) a median enlargement
that is wanting in the others. Certainly we find minor
differences when comparing species with species. If we
look to dimensions, it is only in some species that
Kiitzing observes and figures the two extremes in size,
as, for example, in IV. amphisbaena, (Pl. ii, fig. 42.) For
the rest he contents himself with noting the largest size.
But Ehrenberg observes also the smallest extreme that he
meets with, and delineating exactly the intermediate
forms, puts in evidence the specific characters that re-
niain independently of age and degrees of development.
Treating of the dimensions of these microscopic beings, I
cannot avoid making a few observations. Mohl has
discussed the methods of micrometry in a profound
manner, showing the comparative degree of accuracy to
be attained by them. From that inquiry it appears that
the camera lucida is the most exact and safest of all; I
have found it more convenient than any other. Taking
a glass micrometer (by Plossl) in which a millimetre is
divided into 100 parts, I copy the image of it by the
camera lucida, repeating the operation many times to
ensure the exactness of my copy. Though executed with
an excellent machine, the diamond-marks are never per-
fectly equidistant, and are always too broad to exclude
slight inaccuracies. On this account many trials are
required to obtain a sufficient approximation. From this
copy I can ascertain with precision the amplification
obtained, which is always relative to the vision of the
individual. Whenever I wish to determine the size of
an object, I copy the image with the same combination
of eye-glass and object-glass, with the same camera
lucida, at the same distance; and measuring that upon a
graduated scale, I obtain the dimensions sought tor by
an easy reduction. To abridge and facilitate the inquiry,
I construct a decimal scale on a copy of the micrometer ;
upon this I can draw the divisions, if the magnifying

ANIMAL NATURE OF DIATOMER. 417

power do not exceed 600 diameters, and by causing the
image from the camera lucida to fall upon it, I have its
measurement immediately taken. I have constructed
one of these scales for every combination of my micro-
scope, and thus by a simple application of the camera
lucida, I can measure every object without at all changing
the conditions of the observation. I dwell upon the
method I pursue in my microscopical researches, to prove
that I devote to it scrupulous accuracy. The screw
micrometer also gives millimillimetres, and by the addi-
tion of a nonius even decimillimillimetres; but besides
that ‘it is inconvenient to keep it applied to the plate of
the stage, and that there is great loss of time and inter-
ruption of the observation in applying it when its use
is required, it has always the great inconvenience of waste
of trouble. In ten observations with the screw micro-
meter, we scarcely find two that perfectly agree. With
the camera lucida one only is sufficient. I think it
unnecessary to bring arguments against the method
of applying a glass micrometer over every object we
wish to measure. Still the plan of a micrometer fixed
in the eye-glass, and previously corrected by examining
another micrometer as the object of observation, pos-
sesses great convenience, though not perhaps scrupu-
lous accuracy. But we have not merely to measure the
objects we are about to describe; we must also define
that measurement. It would seem so simple a thing for
all to use the same standard, and there is so much con-
venience in the metrical measure and decimal notation,
that it excites real wonder to see how prevalent among men
of science is the habit of preferring the duodecimal mea-
surement peculiar to every country, and expressing that
in vulgar, not decimal fractions. ‘I'he evil would be less
were any one (standard) adopted, constantly used, and
defined. But the matter is worse than this. Ehrenberg
speaks perpetually of a line, without stating the standard ;
at the same time he gives its equivalent in metrical
admeasurement, and from this it appears that his line is

418 ANIMAL NATURE OF DIATOMER.

equal to two millimetres. This line is one peculiar to
himself; for the line of English measure, which is the
smallest of all, exceeds two millimetres in measurement.
Kiitzing makes use of a linear measure with the same
notation as that used by Ehrenberg,—three small marks,
which usually indicate the millimetre, to the right of the
cipher. It would appear that he intends to speak of
the same conventional line; at least I arrive at this
conclusion from the following comparative table of the
extreme length of some species of Navicula, deduced
from direct observation, from the cipher of Ehrenberg
and that of Kützing, on the double supposition of the
line being conventionally equivalent to two millimetres,
and to the line of the Parisian inch = 2°707 centim., and
from Kiitzing’s figures.*

Navicula ampbisbena . : B ‘ 0-070 millim.
Ehrenberg, 34” : : ‘ 0-100
Kützing, 3” ö ; F F 0-:076—0°104
Kützing’s figure, 0-021 (42) . ' 0-050

Navicula cuspidata : 4 ; ; 0:070
Ehrenberg, 1” ‘ ‘ : & 0.133
Kützing, 4” . : : : : 0-:087—0-117
Kützing’s figure, 0°0242° (428) ‘ ‘ 0:0576

Navicula appendiculata ; i ‘ 0-027
Kiitzing, 4. 5 . 5 ; : 0-037—0-050
Kützing’s figure, 0-0093° (428) i ; 0:022

Navicula viridula ; i ‘ : , 0-047
Kützing, 34” ; : : ; - 0:062—0:084:
Kützing’s figure, 00192 (272) . : 3 0:0457

Navicula gracilis . . : £ j , 0.054
Kützing, 3” 3 z : . 5 0:076—0°104
Kützing’s figure, 0-0207 (422) ; ; 0-049

Navicula major, ; ‘ é : 3 0°235
Ehrenberg, 4" . : : : ; 0:333
Kützing, I” : : : 0:222—0-300
Kützing’s figure, 0°058 (422 : ‘ 0-130

Navicula oblonga ; : : : 0-185
Ehrenberg, 4,” : i R ; R 0:166
Kützing, 17” i ‘ ‘ ‘ 5 0:180—0°246
Kiitzing’s figure, 0:0466 (47). ; 0-110

It results from this table that the ciphers of Kützing
express, in fractions of a line (equal two millimetres),

* In the present translation the decimal numbers indicate millimeters or
parts when not otherwise marked, and parts of a line are given in common
fractions with the sign “’.—Ep.

ANIMAL NATURE OF DIATOMER. 419

measurements in general a little exaggerated; not so
much, however, as those of Ehrenberg ; and the figures
(in Kiitzing’s plates) are rather below the truth, which
we may explain on the supposition that for the sake of
economising space—a bad economy—he has not chosen
to figure the larger individuals. I may add, by way of
confirmation, the measurement of the striee which mark
the shields of every species in constant proportion. In
the WV. viridis, (the viridula of Ehrenberg, not of
Kiitzing,) Ehrenberg states that 13—15 strie are com-
prised in „„ of a line, and Kützing 12—14. I find
seven of these strie constantly in a centimillimetre, 70
im a decimillimetre, and then with a power of 686 I
always find 0:00098 met. between one stria and another,
with the-utmost exactness. Having directly inquired of
Kützing himself, he politely told me, in reply, that he
made use of a micrometer by Plössl, marked upon glass,
in which the Paris line is divided into thirty parts, and
that he placed his object upon this micrometer whenever
he wished to measure it. At the same time he favoured
me with a copy of his micrometer magnified 100
diameters. Now in this copy every division, said to equal
4, of a line, is 000498 met. ; hence such a line would be =
0:00149 met., or something more than half the measure of
the line of Vienna, which is 0:002638 met. Finally, I can-
not quit the subject of dimensions without making another
observation. When we examine many individuals of the
same species, we find both large and small in the process
of deduplication. And we find many of the same size col-
lected together whenever this is the case. Hence it seems
that deduplication may occur at any age. And it seems
to me that the greater the dimensions, the less frequent is
this process ; and I never saw the largest species doubled.
It is a question, when does this process cease? Isit only
the larger individuals, in which no division takes place,
that propagate their species by true reproduction ? or are
some individuals destined from their earliest origin to mul-
tiply by deduplication and others by reproduction? This

420 ANIMAL NATURE OF DIATOMEZ.

is an inquiry that refers as well to Navicule as to all
the other Diatomex, and we have noticed it already
when treating of Cyclotella.

The forms of Navicule of the three following sections
(elliptice, gibbe, nodose,) greatly resemble those of the
Surirelle, differing only by the median aperture. In-
stances of vittae occur in NV. paradowa.

The two species referred to the section dunate belong
to two types entirely different. The one (N. ? genuflewa)
has the two primary surfaces curved, and is a true
Achnanthidea without a stipes; the other, again (N.
lunata), has the secondary surfaces curved, and hence
has analogy only to those Synedre which, exactly under
this point of view, we have compared to the Zunotie.

The siymatelle, or sigmoid Navicule, to the curvature
of the secondary surfaces which we see in some Synedre,
unite the habitual lanceolate form of the Navicule, in
which all the eleven are very like each other. The
greatest difference is that presented by the primary sur-
faces, which are either lanceolate also, or linear.

Now, considermg the Navieul@ collectively in an
organological view, we find, especially in the larger forms,
very important conditions. Along the primary surfaces
run two lines or small canals, terminating at their extre-
mities in distinct foramina, as we have already found in
all the preceding families. And it is around these fora-
mina that the valuable observations of Ehrenberg on
N. major (viridis, Ehr., not Kützing) demonstrate the
currents produced in the ambient liquids, flowing as if
they issued by one extremity and entered by the other.
In each of the secondary surfaces are three ample perfora-
tions, one in the centre and two at the extremities; and,
projecting from the latter, soft bodies, which Ehrenberg
supposes analogous to feet, and subservient to motion.
And it is also in the before-mentioned species that
Ehrenberg saw clearly the ingestion of indigo, and indis-
putable movements in the internal organs “connected
(with the body) by an irritable hyaline jelly, hence often

ANIMAL NATURE OF DIATOMER. 421

exhibiting a tremulous motion.” Whoever has observed
many living Navicule may yet, even after Jong study and
persevering > laborious examination, find himself obliged to
confess, as I do confess, inability to decipher the complex
organisation; but he may also declare, conscientiously,
that he has seen, in these, numerous phenomena perfectly
analogous to those presented by animals, and to which no
vegetable ever presents any similar.

32. AmpuipLuvra.—Individua singularia navicularia
prismatica longitudinaliter sulcata, apertura media nulla.

Kützing observes that mere regard to similarity of form
caused this genus to follow the Mavicule, though the
want of a median aperture excludes it from the Navi-
cules. He might have said the same of some Syzedre.
It is a circumstance worthy of remark, that on account
of the two projecting lines of the secondary surfaces, the
division cannot take place without a species of ‘reduplica-
tion. ‘The one of the three species which is sigmoid
(A. rigida) is curved on the primary surfaces, and under
a double aspect manifests an analogy (not an affinity)
with the Achnanthee. Although the central perfora-
tions are absent, the terminal ones seem to remain in the
Amphipleure.

33. CERATONEIS.—Individua navicularia libera sin-
gularia rostrata, prismatica, quadrangula; apertura media
distincta, terminalibus nullis.

The rostrum only, Kützing says, distinguishes this
genus essentially from Navicula. The first species (C.
laminaris) differs but very slightly in form from some
Navicule, (N. cuspidata, N. rostrata,) but if the terminal
apertures be really absent in this and present in the
others, the organographic difference is great. Of the
other four species, one is sigmoid, (C. Fasciola,) one
contorted and spiral, (C. spiralis,) and two merely arched,
(C. Closterium, C. Arcus). But in the last the symmetry
of the primary surfaces is remarkable, whence there

422 ANIMAL NATURE OF DIATOMES.

results a decided analogy to the Zpithemie, whilst the
resemblance to the Achnanthez, observed by Ehrenberg,
is not apparent ; and I said to the Lpithemia rather than
the Cymbellez because neither Ehrenberg nor Kützing
take any notice of a median aperture on the lateral
surfaces ; with this we are not to confound the umbilicus
projecting from the ventral surface.

34. Stavronkis.—/Individua libera, singularia, navi-
cularia; apertura media transversal.

The numerous species (34) of this genus, divided into
three sections /eves, (genuine,) punctate (Stictoneis)
striate (Stauroptera) do not differ from Navicula except
by the transverse direction of the aperture, a condition
on whose organographical value we cannot pronounce
any judgment, not knowing the office of this aperture,
nor its relation to internal structure. Still it is right to
observe that in many species it does not seem to be the
aperture itself that is placed transversely, but rather the
depression, at the bottom of which is found a round
perforation, as in Navicula, and, as in these, there is a
sort of funnel stretching into the cavity, which becomes
visible when we look in front of the primary surface.

35. AMPHIPRORA.—Individua libera, singularia, aper-
turis terminalibus binis mediis, nee marginalibus.

From the figures of two out of three species, which
Kützing describes in this genus, it appears to me that
we may believe the two terminal apertures constituting
the essential character of this genus, to be nothing more
than the usual minute foramina which serve to terminate
the two longitudinal lines or canals that traverse the
primary surfaces of almost all Mavicule. Nor perhaps
are central apertures wanting in the lateral surfaces;
but these are seen in profile in the figures referred to.
The so-called wings, (a/@) or projections, belong, therefore,
to the secondary surfaces, and constitute the only dis-
tinctive character of the Amphiprore.

ANIMAL NATURE OF DIATOMER. 423

36. Ampuora.—Individua libera, singularia, aperturis
mediis binis lateralibus, terminalibus nullis 1. obsoletis.

The Amphore are Cymbelle with primary surfaces
equal, and secondary surfaces symmetrically convex,
instead of plane and inclined. We have yet to learn
whether the two median lateral perforations exist on one
part only or both. In the first case the analogy would
be complete; in the second, every Amphora might be
called a double Cyméella. And indeed the two ‘indivi-
duals into which every Amphora divides itself, by de-
duplication greatly resemble two Cymdelle. Yet perhaps
this resemblance 1s only apparent. In the Cyméelle there
is one primary surface, the dorsal, which forms the
convexity. Again, in the middle of the Amphore the
convexity is itself referable to that one of the secondary
surfaces which remains. The Cymdelle, in subdividing,
give origin to two complete individuals. ‘The two indi-
viduals proceeding from the division of the Amphore are
wanting in one of the two lateral convexities ; their lateral
surface, of new origin, ought to become convex, like the
other. In the Cymöell@ there occurs a simple division
or deduplication; in the Amphore the division or dedu-
plication is succeeded by a species of reduplication. It
results, from this conformation, that in the Amphore the
navicular figure is only apparently similar to that of the
Navicule. The one is navicular in the secondary surfaces,
the other in the primary, because of the prominence of the
secondary. The division of Wavicule is parallel to the
elliptical or rhomboidal surfaces; in the Amphore it is
vertical to these (surfaces). J therefore absolutely exclude
the A. atomus from this genus, as it is a Navicula or a
Synedra. The doubt raised by Kützing as to the
A. elliptice appears a certainty to me; no central aper-
ture in the primary surfaces being admissible. On the
same motive I assert that if the A. acutiuscula do truly
belong to this genus, the figure 1 (Pl. V, fig. 32) is
incorrect, for it represents a median aperture; and
equally so is the third figure (Pl. XX, fig. 18) of the

424 ANIMAL NATURE OF DIATOMER.

A. hyalina, by the same author. In respect to the
median lateral perforations, besides the already expressed
doubt whether they exist on both the primary surfaces
or only on one, it is also to be observed that they are
wanting in six, (4. venefa, A. aponina, A. coffeaformis
B. Fischeri, A. acutiuscula, A. borealis,) out of the
eighteen species assigned by Kiitzing to this genus.

37. Diapesmıs. —/ndividua navicularia in fascias
elongatas (biconvexas) arcta conjuncta; aperture medie
singulares et terminales bine distincte.

In 1836, Kützing published (Dec. xvi, n. 153) the new
genus Brachysira: “ frons minutissima constituta e frus-
tulis paralleliter et irregulariter coadunatis.” Now, ın
his Monograph of Diatomez, he makes no mention either
of the genus or the species (B. aponina) which was
nothing more than N. appendiculata. Nay more, there
is enumerated among the Naviculee the Brachysira
serians of Brebisson, and Bailey’s fine observation on
N. major (N. viridis, Ehr.) is suppressed, “ that it is not
rare to meet with four, sometimes even eight, united
laterally.” The genus Diadesmis is established, however,
in which the Navicule are arranged in rows exactly as in
the species just described, only perhaps with more con-
stancy and regularity. Yet the foundation of this genus
is justified by analogy with other families, and by that
sunilarity of genus 1 the parallel series which perhaps
is supremely attractive in systematic classification. But
independently of the value of the genus, which I do
not controvert, the organic condition of this concate-
nation in the Liadesmw and Sphenosire seems to fur-
nish important considerations. If the central aperture
of the secondary surfaces were really stomatic, serving
to the ingestion of aliment, we might suppose that, in
respect to the individuals contained in the midst of
these fascia, that, unlike the terminal ones, they took their
nutriment mediately. Although such a condition occurs
in other classes of animals, yet in our case it is purely

ANIMAL NATURE OF DIATOMER. 425

hypothetical. Now in opposition to this hypothesis
stands the fact of all the Diatomeze destitute of this aper-
ture. Instead of it, we find in almost all of them the
presence of two terminal perforations of the primary
surfaces, always so situated, even in associations of
numerous individuals, that they can perform their func-
tions freely. The minuteness of these apertures would
be adapted to the tenuity of the food they were in-
tended to receive, and might, in some degree, explain
why nothing can be discerned as to the nature of this
food or the conformation of the digestive organs, whilst
in other Infusoria, even of smaller dimensions, the sub-
stances received can be clearly distinguished. And
although the terminal apertures of the secondary surfaces
may seem to belong to organs of motion, (as Ehrenberg
has described, in some of the larger species, and as appears
indicated also by the nature and direction of the move-
ments themselves,) still it is a reasonable supposition for
any one to believe that the median aperture is subser-
vient rather to the generative function.

38. FrustuLia.— /ndividua navicularia, in substantia
gelinea amorpha nidulantia.

The only character that distinguishes this genus from
the Wavicule is the presence of a mucous envelope. In
one of the two species (P. maritima) the Navicule are
included in various numbers within a distinct cell.
Again, in another, (F. salina) the enveloping mucus is
amorphous. By the same character Ehrenberg compre-
hended also in this genus that N. appendiculata of which
Kützing had constructed his genus Brachysira. Organo-
graphically, the Frustulie show the transition of the free
to the included Naviculeze.

39. BerKeLeYA.— Phycoma gelineum molle basi
globosum, ramos filiformes naviculis dense aggregatis
repletos emittens.

In this and the two succeeding genera (Raphidogloea,
Homeocladia,) there is not merely wanting the primary

426 ANIMAL NATURE OF DIATOMEE.

character of Naviculex, the central aperture, but even
the form of the shields corresponds to that of many
Synedre of the sections Scaphuluria and Echinaria ;
hence they seem rather to belong to the family of
Surirelleze in the preceding order.

40. Rapuipocitas.—Plhycoma globosum gelineum
nolle, intus fasciculis navicularum in fila radiantia
dispositis farctum.

The principal character of this genus is taken from the
amorphous disposition of the gelatinous substance, in
which the Navicule, or rather the Synedre are immersed.
Under this point of view the genus Berkeleya is inter-
mediate between the Raphidoglea and the Homeocladia,
But it is the characteristic disposition of these Synedree,
that whilst they are mixed together in a disorderly
manner in the preceding genus, and fasciculated almost
in a parallel manner in the following one, in this they
are arranged in fusiform fascize, confluent by the pointed
extremities. Whether we consider the first or the second
of these characters, I doubt whether we can regard them
as sufficient to distinguish the three genera. In one of
the four species enumerated by Kützing (2. manipulata)
the great variety in the size of the Synedree is remark-
able ; he says they vary from 4rd to ith of a line, but
with an amplification of 420 diameters he delineates
them from 7 to 25 millimetres, corresponding therefore
to 0:0166 millim.—0°0595 millim.

41. HommocLanıa — Phycoma filiforme ramosum, ex
tubo gelineo intus fasciculis navicularum linearium
elongatarum bacillariarium farclo compositum.

In confirmation of what has been already stated of the
difficulties attending the distinction of these genera, I
have subjoined the description of a new Homeocladia,
which in external figure bears a striking resemblance to
the Raphidoglee, and in its association of filaments
might perhaps be referred to the Berkeleye.

ANIMAL NATURE OF DIATOMEA. 427

H. heloides pumila, parasitica, adnata, filis tenuibus
e centro radiantibus, dichotomis sensim attenuatis; syne-
dris, continue fasciculatis, mediocribus, e facie linearibus,
e latere oblongo ellipticis, obtusis.

Schizonema helioides, Ganard, in litt. Ad Uloam latis-
simam legit Daimatie Sandri. Frons. 3 mill. vie attingens
Rivularia adspectum omnino presefert. Fila ad basim
0°02 mill. vie crassa et, ut in Rivulartis, rotundata.
Longitudo Synedrarum 0:039 mill., latitudo 0:0043 mill.

In this genus, too, we may notice the greatest variety
of dimensions. ‘Thus, for example, Kützing gives the
length of the Synedra of H. pumila 2/”, which, referred as
he states to the Paris line, corresponds to 0:079 millim.
But in the figure with an amplification of 420 linear, it
only equals 0'016 met., and therefore corresponds to
0:0383 millim. Now I find the length to vary in my
specimens from 0:0457 millim. to 0°078 millim., and
therefore not far from the extremes above described.
This same species also presents in its thick inferior
trunk, and in the fasciculato-fusiform disposition of its
Synedr, rather more relation to the two preceding
genera. Kützing refers my Schizonema ruorum to this
genus Homeocladia; and justly, for it certainly does
not belong to the Schizoneme. But I think he might
just as properly refer it to the Berkleye, on account
of the thickness of the walls of the mucous threads, and
the uniform confusion (affustelmento) of the Synedr«.
As to the dimensions of these last, Kützing says they
correspond to those of the Raphidoglea interrupta ; but
this accords little with Kützing’s figure magnified 420
linear ; this is 0:023 metr., and therefore corresponds to
0:054 millim.; it accords much less with the measure-
ment indicated (4), which is = 0'108 millim., though
the greatest length of these Synedre in my H. lubrica
is = 0°04 millim. Of the seven species yet known in
this genus, two only (anglica, Martiana,) present mar-
ginal strie on the lateral surfaces; this makes them far
more similar to the Syxedre.

428 ANIMAL NATURE OF DIATOMEE.

42. ScHIzonEMA.—Phycoma filiforme tenue luaum, ex
tubo gelineo (celoma) ramoso naviculas abbreviatas longi-
tudinaliter seriatas fovente compositum. Spermatia
externa simplicia tubo adnata sessilia.

The characteristic differences between this genus and
the following one (Miceromega) assigned by Kiitzing,
correspond with those proposed by Agardh (Conspect.
crit. Diatom. 1830), in which, after rejecting the divi-
sion, previously suggested by Greville, of the two genera
Monema and Schizonema, he is induced by observation
to admit it in fact, obstinately insisting on rejecting it
in name. It is a lamentable thing, and the primary
source of the confusion that all deplore in the synonyms
of botany and zoology, that a mistaken vanity frequently
induces authors to maintain their own errors with perti-
nacity, and blindly to reject the opinions of others.
Greville divides the Schizoneme of Agardh into two,
Monema and Schizonema ; Agardh maintains that the dif-
ference between them rests solely on a different degree
of organic development, which it is often difficult to dis-
cover; therefore he recasts the two genera into one.
Somewhat later Agardh finds certain species in which
the character defined by Greville, as distinctive of the
genus Schizonema, is evident. When he discovered his
own error he ought to have restored to Greville both the
genus Alonema, and the species taken from it. But it
was too hard a case; so he turned round to establish a
new genus (J/icromega), and refer to it the true Schizo-
nem@ of Greville; thus taking away from that author
all the species that he had judiciously divided into two
genera. The scholars blindly follow their master. The
same story, changing the names, may be applied to many
questions of synonyms. If the two genera be really
distinct, their names ought to be Alonema (Schizonema,
Ag. and Kiitz.) and Schizonema (Micromega, Ag. and
Kiitz.); nor can we adopt the opinion of Ehrenberg,
who, disapproving of the elision in the word Monema
(Mononema), as if there were no legitimate examples,

ANIMAL NATURE OF DIATOMEE. 429

rejects it as erroneous, and substitutes in its stead a new
name (Naunema) applicable to the two genera which he
reunites, It is doubtful whether the right of priority
ought to be assigned to the Hydrolinum of Link, which
along with a Monema, comprised an Alga (Conferva
Hermanni), and therefore cannot be considered suf-
ficiently definite. The name Monema, which on account
of its elision should be written Monnema, applied to the
species constituted of a single tube including the
Navicule, and placed in comparison with the rest,
(Schizonema), referable to the species where the single
series of Naviculz have a proper tube, and the union of
these threads (fili) constitutes the frond, is so much the
more exact since the second, Schizonema, both by ety-
mology and generic character of Agardh himself, as
mentioned already, (Systema Alyarum, 1824,) denotes
this condition in a graphical manner. ‘There is still an
important character described by Kiitzing in reference to
the position of the organs which he terms spermatia.
These are external in Monnema (Schizonema), immersed
again in the Schezoneme (Micromega), as if intimately
allied to the simple or compound structure of the external
tube. Now after the consideration of such characters,
the result of an attentive examination is my conviction
that some species referred by Kiitzing to the first of
these genera belong really to the second; and, for the
reasons just stated, these will be all entitled to the name
assigned by Kiitzing, whilst all the other species of
Schizonema should become Monnema, and those for
which the name Micromega was uselessly created, should
become Schizonema.

This discordance of opinion as to the arrangement of
some species in one or other of the two genera, which,
independently of their names, appear so distinct and so
clearly defined, arises from the great difficulty of dis-
cerning the parallel tubes, including the particular (sın-
‚gole) series of Navicule. In some species the wall of
the external tube is clearly distinct, and the Navicula are

430 ANIMAL NATURE OF DIATOMER.

confused within; but in some others it seems as if
instead of a tube there is a mucous mass in which the
Navicule are immersed. ‘hen there remains a doubt
whether the series of these Navicule are included in
distinct tubes or in simple canals hollowed out of the
common mucous mass. It may perhaps be suspected
that the tubes visible in specimens that have been
moistened, do not really exist during life, and originate
in a change that has taken place after death. And it is
quite certain that the partial tubes waste away sometimes,
as well during life as by some alteration happening after
death, so that they appear evident in some but not in
other parts of the same specimen. The character indi-
cated by Kützing of the so-called spermatia, external
in Alonneme (Schizonema, Kütz.), and internal in Schizo-
neme (Micromega, Kütz.), would therefore assist us very
much, were it constant and capable of being verified.
But Kützing himself only found these spermatia external
in a single species (S. fenue). ‘Therefore there only
remains the sole negative character of the absence of
partial tubes, and whenever we succeed in observing
these, the species must undoubtedly be referred to the
succeeding genus. ‘I'he absence of partial tubes, and
consequently confused disposition of the Navicule, is
evident in the following species.

Monnema quadripunctatum, Grev.

Kiitzing changed Lyngbye’s specific name (Bangia
quadripunctata) as erroneous, and substituted that of
Schizonema tenellum ; establishing the length of the
Navicule, from Lyngbye’ s original specimens, to be
as”, which, in the Paris line, would equal 0023 millim.
But, with an amplifying power of 420, he represents it no
more than 5°5 millim., which is equal to 0°0131 millim.
Estimating this line conventionally at 2 millim., „th of this
would be 0-017 millim., and there would be more agree-
ment. But upon an original specimen with the same
name he establishes another species (S. Lhrenbergit)

ANIMAL NATURE OF DIATOMER. 431

which he pronounces synonymous with the Naunema
Dillwynit of Ehrenberg. In this he says the Navicule
are ys long, or 0:0246 millim.; but he represents
them 5 millim. with a power of 420, corresponding
therefore to 0-012 millim. Here again there is ground
for the same consideration, as to the slight difference
we should meet with between the size of the figures
and the admeasurement, were the latter understood
as expressed conventionally in lines equal to two mil-
limetres. It seems to be so from the figures of
Lyngbye and Greville, but not from either of the two
species of Kiitzing. We are led to this supposition by
an observation of Harvey, who says, that in the AZ. qua-
dripunctatum the Navicule are larger than in any other
English species, whilst by Kiitzing’s description, and still
more by his figures, there would seem to be only two of
these in which the Navicule are of smaller dimensions.
Harvey says, that specimens from Carmichael differ in
external appearance from those of Mrs. Griffiths, though
agreeing as to internal structure.

I received from Lenormand a specimen from Calvados,
with the name Schizonema quadripunctatum, in which the
length of the Naviculz was 0:024”.

Here it seems right to mention some different species,
all belonging to the genus Monnema.

Monnema tenuissimum, Kütz., (Schizonema.)

Having been favoured by Kützing with an authentic
specimen of this his species, I could with certainty
compare it with specimens from Venice sent to me b
Kellner. I have ascertained that the length of the
Naviculaee = 0°022 millim. This would agree sufficiently
with that indicated by Kützing in the description, where
he says it is 4th of a Paris line, or — 0:0246 millim.
But he figures these Naviculz with an amplification of 420,
no more than 4°5 millim. which corresponds to 0°0107
millim. Here it seems, then, that the measurement
expressed in the description ought really to be understood

432 ANIMAL NATURE OT DIATOMER.

in relation to the Paris line, or still better, to the smaller
one of Vienna, whilst, on the other hand, the figure would
disagree less with the admeasurement interpreted by the
conventional value of 2 millim., although „th of such a
line would be equal to 0°0184 millim.

Alonnema tenue, Kütz., (Schizonema.)

As in the preceding species, I also find in the authentic
specimen of Kiitzing, as well as in others which I have
examined, that the size of the Navicule corresponds to
the measure described in the definition in the line of
Paris (45 = 0°027 millim.) whilst the figure given with an
amplification of 420 diameters is only 5 millim., and
therefore corresponds to 0-012 millim.

In this species Kützing observed the presence and
development of the spermatia.

Kützing observes that his S. ¢exwe does not correspond
with the &. Zenxe of Agardh, therefore he ought to have
changed the name.

Except for the figure of Agardh there is reason to
suspect that it belongs to a true Schizonema, though
published together with dlicromege, which combine
a coriaceous consistence with the essential character
of partial tubes (‘Icon. Algar. Europ.,’ fase. i, tab. 3.)
I find, on the other hand, that the Schizonema frequent
in the Lagunes of Venice, by me denominated 8. adiv-
aticum, is referable to this species, and not to the pre-
ceding one, where Kützing would place it, and I persist
in regarding it as corresponding to the definition and
description which Agardh gives of this his own species.

Under the name of Schizonema comoides, to which it
certainly does not belong, I received from Lenormand a
beautiful species allied to the preceding, but in which
the Navicula are constantly smaller, scarcely measuring
0-018 millim. in length. Im these, the so-called external
spermatia are very abundant. ‘This is an important
species, because the Navicula, being very stipitate, and

ANIMAL NATURE OF DIATOMEA. 433

many times seriate, it becomes extremely difficult to
convince one’s self that the partial tubes are absent, and
the presence of external spermatia is really in accordance
with that absence.

From the Lenormand I also received, under the name
of Schizonema Grevillei, inapplicable to it, another very
beautiful species, with very fine short threads, in which
the Naviculz are not only still shorter (0-017 millim.) but
also narrower (0°0045 millim.) and very acute.

Monnema rutilans, Ag., (Schizonema.)

In authentic specimens from Kützing and Jürgens, I
find the length of the Navicule 0-025 millim., and their
breadth only 0:004. Kützing says their length is 4,” or
0'027, with the usual contradiction of a much smaller
figure. In this the Navicule are only 7'7 millim., which,
with a power of 420 corresponds to 0-018.

I have no specimens of the two forms which Kützing
considers to be varieties of the preceding, with the names
S. parvulum, S. lubricum.

Monnema Hoffmanni, Ag., (Schizonema.)

In a specimen with which I was favoured by Kiitzing,
I find fhe Naviculz 0:03 millim. Jong, and 0:0064 broad,
corresponding to the description of Kiitzing, and larger
than his figure (9°5 millim. 4, = 0°0226).

I cannot understand why Kützing gives this form as a
variety of the preceding, whilst in external characters, in
the dimensions and the shape of the Naviculz, there are
distinctive appearances sufficient and comparable to those
by which other species are distinguished.

Monnema ectocarpoides, Mgh.
Schizonema viride, Ktz.

The enforcement of the law of priority is, without

434: ANIMAL NATURE OF DIATOMRE.

offence to modesty, or culpable charge of vain glory, as
applicable to matters of our own as to those of another.
Kützing, in quoting the name given to this species by
me, of necessity condemns the one proposed by himself,
since J had previously established, though I had not pub-
lished it. He might have spared me one of the two names,
but he would not. In the description, he gives the size
of the Navicule 2; of a Paris line or 0°027 millim.
But in the figure, with the same power of 420 diameters,
he delineates the Navicule 8 and 15 millimetres long =
0:019—0'038 millim. On the other hand, I have never
found the Navicule shorter than 0:02, or longer than
0:031, either in the authentic specimen of Kützing, or
in the numerous ones from the Adriatic. The breadth
is constantly a fifth of the length.

This form, too, is regarded by Kiitzing as a variety of
the S. rutilans, 1 know not on what motive.

As to Ehrenberg’s synonym (Maunema balticum),
quoted by Kützing; that author determines the length
of the Navicule 7, of his conventional line; equivalent to
~ of a millimetre, or 0°0069 millim., he draws it no less
than 16 millim., and speaks of transverse strie, 15 to 20 of
which are included in 4 of a line, which, notwithstanding
the amplification of 2300 diameters and upwards, are
not to be discerned in the figure.

Monnema Dillwynii, Grev.

Kützing states the length of the Navicule to be ith of
a Paris line, or 0°0318, but he figures the length as
6 millim., with an amplification of 420, which corre-
sponds to 0°0142. In authentic specimens received from
Berkeley, and corresponding perfectly with Kützing’s
description and figure, I find the length of the Navicule
0-022 millim., the breadth of the primary surfaces 0:007,
that of the secondary 0'005.

ANIMAL NATURE OF DIATOMES. 435

Monnema Lenormandi, Ktz. in litt, (Schizonema.)

Under the name of Schizonema Dillwynti, Lenormand
favoured me with a A/oxnema from Calvados, differing
greatly from the preceding. I wrote to Kützing, who
replied that he had already created a species with the
name S. Lenormandi, sending me in confirmation a frag-
ment of his specimen. "Ihe Naviculz are 0:0255 millim.
in length, and attain a breadth of 0°04 in the primary
surfaces, when they are near the state of duplication.

Monnema sordidum, Kütz., (Schizonema.)

Kützing establishes the length of the Navicule 4,
„th of the Paris line, or 0°0270—0-0225 millim., and
moreover refers to this species specimens from the lagunes
of Venice, corresponding in all other characters, the
Naviculze being 0°0245 millim. in length, and 0:0064 in
breadth, both on the primary surfaces, which are lineari-
rotundate, and on the elliptico-linear, obtuse secondary.
In a specimen with which I was favoured by Kiitzing, I
was not able to see the Naviculz clearly, but they seemed
to me somewhat smaller, not, however, so much so as in
this author’s figure (5 millim. 3,= 0°0119).

Monnema Grevillei, Harv.

This is one of the most instructive species, for the
Navicule are frequently placed transversely, in such a
way as to demonstrate the total absence of partial tubes.
It is interesting also from the large size of the Navicula,
which exhibit the process of duplication very clearly. In
these, too, Kiitzing saw the central aperture. In the
specimen with which I was favoured by Berkeley, under
the name of S. Grevillei (Alg. Danm.) and S. guadripunc-
tatum, Ag, I find the greatest dimension of the Navicula to
be 0:034 millim. in length, and 0:016 in breadth, as well
on the primary surfaces, which are a sort of parallelogram
with the angles slightly rounded, as on the secondary,
that are broadly elliptico-obtuse. This differs little from

436 ANIMAL NATURE OF DIATOMEE.

the figure given by Kützing, magnified as usual, 420
diameters, which, being 13 millim. long, corresponds to
0:0309. But the dimensions given in the definition (45 =
0:564 millim.), are much greater.

Monnema subinconsprcuum, Mgh.

Tfound it at Trieste, parasitic upon Letocarpus arctus,
along with other Diatomee.

The threads, or fi/aments, are scarcely a millimetre long,
and are 0°085 broad. The Naviculz are 0:02 long, and
0:005 broad, as well on the primary surfaces as on the
secondary.

The simplicity of the filaments had led me to believe
that the species corresponded to Naumena simplex of
Ehrenberg, excluding the synonym of S. fenwe of Agardh.
But the dimensions stated in the description (4—xth of
a line, or 0:0052—0-0104 millim.), and the paucity of the
Naviculz included in the gigantic figure, seem to con-
tradict that association.

Among the species ascribed by Harvey to the genus
Alonnema (regarded by him as a simple sub-genus), the
four following are unknown to me; spadiceum, Grev. ;
virescens, Harv.; dubium, Harv.; ertnoideum, Harv. Three
others (zmplicatum, parasiticum, comoides), belong to the
subsequent genus. ‘The last (prostratum) is an Encyonema.

Of the remaining species described by Kiitzing as
Schizouema, and, therefore, wanting in partial tubes, I
infer from direct observation of authentic specimens, that
some belong to the following genus; wraneosum; trichoce-
phalum; Smithii; helminthosum; scoparium ; sirospermune.
Of others I believe the same, from the figures of Kützing,
which disclose either partial tabes or so regular a linear
arrangement of Navicula as is never met with in Monneme;
minutum, humile, floccosum, crispam, plumosum, capi-
tatum, Bryopsis, Arbuscula, hydruroides, mucosum. But
the two species /utescens and striolatum, which I do not
possess, appear to be true Monneme.

Finally, with respect to Schizonema tllyricum, in which

ANIMAL NATURE OF DIATOMEA. 437

Kützing describes and figures the Naviculz as disfigured
by desiccation, I ought to state that I have observed
such Navicule and thought them specifically character-
isticof a Schizonema, which, for this reason, 1 denominated
S. Cercaria. I have ascertained subsequently that the
Naviculee of many species undergo a similar alteration.
It takes place more frequently in the Micromege or true
Schizoneme of that genus than in Monneme. It ap-
pears that sometimes, perhaps in certain physiological
or abnormal conditions, the solid substance of the shield
is redissolved. The appendages, too, with which the
disfigured Navicule: seem, in such cases, to be furnished,
are due to the partial tube, which closes upon them
(vi st addossa), grows thin, and bursts.

43. Micromrca.—‘‘Phycoma filiforme ramosum, tubo
communt externo cinctum, ex naviculis seriatis compo-
situm. Series navicularum singulares tubulis internis
minoribus proprüs (secunduriis) vel fibris tenerrimis cur-
vatis bierispis cincte. Spermatia immersa, ex dilatatione
navicularum oriunda.”

From what has previously been stated, it would seem
to be proved that, by the laws of nomenclature, we ought
to maintain the name of Schizonema for this genus: 1st.
Because Agardh established this genus (Systema, 1824)
with a definition indicating an essential generic character
which distinguishes it from the preceding, “ fila fascie-
formia e filis angustioribus coadunatis composita, granula
elliptica includentibus, in que iterum secedunt.” 2d. Be-
cause, in the very description succeeding the definition,
he insists upon this organic condition “ Composite
(plante) sunt e pluribus individuis licet filiformibus, iterum
includentibus eadem fere corpuscula que in Frustulia et
Meridione invenimus.” And he adds this excellent cha-
racter of the mode of branching, “ Ramosa apparent, et
ab auctoribus ita describuntur, quod tantum ex fissione
filorum oritur.” 8d. Of the ten species ascribed in this
work, for the first time, and all contemporaneously, to

4838 ANIMAL NATURE OF DIATOMEE.

the genus Schizonema, four (Smithü, corymbosum, apicu-
latum, ramosissimum) really belong to it in the sense we
have assigned ; three, again, belong to the genus J/onnema
(rutilans, quadripunctatum, Dillwynit) ; two are uncertain
(lacustre, Grateloupii) ; and one (micans) must be referred
to another genus (Raphidoglea). 4th. ‘Ihe distinction
established by Greville is well expressed in the character
of the genus J/onnema, of which he takes 4/. guadripune-
tatum as a type, establishing, at the same time, as the
type of Schizoneme, the S. Smithii. 5th. When Agardh
(1828) discovered the structure of Micromega, he found
that many species, which he had formerly ascribed to the
genus Schizonema, presented the same appearances, and
he referred some of them to his new genus in his ‘ Con-
spectus criticus’ (1830). A greater or less rigidity of
cartilage is not a sufficient character for the distinction
of genera; and, in fact, we find that it lends little aid in
the determmation of species, when employed, as it is
by Kützing, in his subdivision of the genus Micromega
into two sections. It varies, moreover, exceedingly in the
same species.

In respect to Kiitzing’s definition, we have only to
notice the fine crisped fibres which he seems to have
seen encircling the series of Naviculae sometimes, instead
of the characteristic partial tubes. I have never hap-
pened to see these fibres. In every species I have been
able to examine, I always saw, with greater or smaller
degree of difficulty, but always distinctly, the partial
tubes. Sometimes, certainly, I have seen these tubes
so fine, so transparent, so colourless, that, at first sight,
they only seemed to be fine margins. By the aid of
some reagent, especially of a solution of iodine more or
less concentrated, with or without the addition of sul-
phuric acid, moderating or interrupting its previous or
subsequent reaction, I have succeeded in clearly perceiv-
ing the partial tubes. I cahnot suppose that the action
of these reagents would produce such a coagulation of
the surrounding amorphous mucous substance, as to

ANIMAL NATURE OF DIATOMEA. 439

simulate the tubes themselves; for the coagulation could
not produce regular tubes, and moreover the presence of
these tubes is always accompanied by a regularly seriated
disposition of the Navicule. There can only remain
the supposition already mentioned, that besides the pre-
sence of a single enclosing tube, as in Monneme, and
that of partial tubes, characteristic of the Schizoneme,
there may be a third condition, that of a continuous
mucous substance in which single Navicule or the
entire series of them may be imbedded. And this third
condition according to the changes induced, and es-
pecially in consequence of desiccation and perhaps of the
use of chemical reagents, may simulate either one or both
these opposite conditions. Finally, in respect to the
partial tubes, I perceive that frequently, where they
remain empty of Navicule, they are so contracted and
contorted as to appear like nothing but the finest threads,
which often unite the remaining Navicule together by
their apices. And the condition I have before described,
when treating of the filiform appendages with which
Navicule sometimes appeared to be furnished (v. &$.
Illyricum,) is the same which is seen also in the figure
given by Ehrenberg of his Naunema Agardhii. Therefore,
without pronouncing any judgment on the fibres indi-
cated by Kützing, I express merely my own supposition
that their apparent presence may be produced by the
partial tubes themselves. :

To the organic condition of the so-called internal
spermatia, prudently noticed by Kiitzing, I think we
ought to refer the circumstance of the great variety of
dimensions presented by Navicule, not only in the same
species, but very frequently in the same specimen. Varie-
ties are often met with in different individuals which an
attentive examination compels us to recognise as belongin
to the same species, while within the same thread all are
found to be equal. In the Schizoneme, on the other
hand, we find, mixed amongst the larger Naviculz, others
that are less, and some very small, scarcely visible with

440 ANIMAL NATURE OF DIATOMER.

the highest powers of the microscope. It seems as if
the so-called external spermatia of the AZonneme become
detached before development, as Kiitzing observed, in
one species; and that in the Schizoneme, on the con-
trary, these spermatia, if we regard their internal collo-
cation, become developed within the cavity of the
generating frond.

This is one of the principal reasons why the deter-
mination of species becomes extremely difficult. Others
may be mentioned: the immense number of species ; the
excessive variations of external form; the want of agree-
ment between the measurements indicated by Kützing
in his descriptions and those of his figures, and those
also deduced by direct observation from authentic speci-
mens; finally, the very intricate synonymy, impossible to
disentangle when we have not before the eye, authentic
specimens of all the species, to mstitute a comparison.

Kiitzing describes and figures twenty-four with won-
derful accuracy. ‘To these I think that eighteen, ascribed
by him to the preceding genus, ought to be added; and
not a few still remain to be denominated and described.
We will be as concise as possible.

Schizonema implicatum, Harv.
Micromega intricatum, Kütz.

Kiitzing does not give any reason for changing the
name.
Schizonema parisiticum, Griffiths.

Kützing says the Naviculz are „th of a Paris line, or
0:0235 millim. He figures the largest of them 4 millim.,
corresponding to 0°0095. In an authentic specimen
received from Berkeley, as well as in those from
Lenormand and Brebisson, under the name of 8. rutilans,
and corresponding exactly with the first, I find the
greatest length of the Navicule 0°02 millim., and the
greatest breadth 0:005.

ANIMAL NATURE OF DIATOMES. 441

Schizonema bombycinum, Kiitz., (Micromega.)
Schizonema patens, Kütz., (Micromega.)
Schizonema flagelliferum, Kütz., (Micromega.)
Schizonema lineatum, Kiitz., (Micromega.)

Kützing says the Navicule are 1 to jth of a line in
length, or 0:0246 to 0'027 millim. The largest of his
figures is 6°5, corresponding to 00155. In an authentic
specimen from Spalato, with which Kiitzing obliged me,
and in the corresponding ones from Zara, collected hy
Sandri, the extreme length of the Navicule is 0:02,
and the greatest breadth of the primary surfaces is
0:0047 millim.

Schizonema floccosum, Rudolph, (not Kütz.)

The length of the Navicule indicated by Kützing is
ath of his line, or 0°045 millim. In specimens collected
in Dalmatia by Vidovich, which correspond with the
description, the greatest length of the Navicule is 0:046,
the breadth of the primary surfaces 0°005 millim., in single
individuals ; the breadth of individuals very near a state
of duplication was almost double, and that of the se-
condary surfaces, which are elliptico-rhomboidal, 0°009.
In this very distinct species the extraordinary thickness
of the partial tubes is remarkable; they are often more
than double the breadth of the Navicule.

Schizonema hyalinum, Kütz., (Micromega.)

The length assigned by Kützing is 3; to „th of a line
— 0'0416 to 0:0338 millim. The greatest length, in plate
xxiv, is represented (#2) 7°5, or 0°0179, and the greatest
breadth, in plate xxv, 1°5, or 0:0036 millim. In numerous
specimens from Dalmatia, transmitted to me by Vidovich,
and corresponding perfectly to the descriptions and the
figures, I find the greatest length 0°034, and the

442 ANIMAL NATURE OF DIATOMER,

greatest breadth of primary, as well as of the linear-
lanceolate secondary surfaces, 0:004 millim.

Schizonema tenellum, Kütz., (Micromega.)
Schizonema Hyalopus, Kütz., (Micromega.)
Schizonema ramosissimum, Agardh.

Kützing says that the Navicule are „th of a line long,
or 0°045 millim., but he figures them only as 77 =
0:0183, and the very small 0°0024. In a specimen from
Lenormand, and in some from Dalmatia, collected by
Vidovich, corresponding in external appearance, and other
characters, with Kützing’s figures and description, I also
find the greatest length 0:028, the breadth of the primary
surfaces 6005, and that of the elliptico-elongate obtuse
secondary surfaces 0:0064 millim.

In an authentic specimen from Chamin, obligingly
sent to me by Desmazicres, with the name of Schizonema
apiculatum, which is cited by Agardh himself as belonging
to S. ramosissimum, and which differs a little from the
preceding, the Navicule attain 0°054 in length; more
frequently they are only 0'042. The primary surfaces
are linear; the secondary, elliptico-elongate, rather larger,
are a quarter of the length in breadth. Many smaller
ones (0°02) are mingled with the others.

Under the same name of S. ramosissimum I received
from Harvey and Berkeley a species entirely different
from Kützing’s, and corresponding perfectly with the
description and Agure given by Kützing of his &. strio-
latum. In this the transverse strize upon the external
surface are very evident. Although Kiitzing does not
state the dimensions of the Naviculee in his definition, those
represented in his plate, and calculated by the usual rule
as equalling half the indicated amplification, would be
twice as large. In our own, the greatest length is 0°018
millim., and is not quite three times the breadth of the
primary surfaces. In the figure of S. striolatum, the greatest

ANIMAL NATURE OF DIATOMEA. 443

length is 7°5 millim. (#2) = 0°18, and is almost four times
the breadth.

Schizonema setaceum, Kütz., (Micromega.)

The length assigned by the author 4 to 4 of a line =
0°0467 to 0-045 millim., delineated 8-2 millim. (2%) =
0:0195.

In an authentic specimen from Kützing, and in those
that I refer to this species, I find the Naviculae 0-02 millim.
long, but considerably broader than the figures of this
author; the primary surfaces being 0'004, and the
secondary 0°07, whence the shape becomes manifestly
elliptical.

Schizonema aureum, Kütz., (Micromega.)

Although Kützing has indicated no other locality than
Sidmouth, I refer to this species some specimens that I
collected at Zava, which correspond perfectly with this
author’s description and figure. The Naviculs are 0'032
millim. long, (Kützing says they are 4 line = 0:0338
millim.; and represents them 7 millim. 4° = 0-0166,) and
are 0-006 in breadth of primary surface, and a millimilli-
metre more in the secondary. In this species I have
seen single Navicule with swollen internal spermatia, as
Kützing delineates in his J. polyclados, to which at
first I thought it must belong.

Schizonema corymbosum, Ag.
Schizonema myaxacanthum, Kütz., (Micromega.)

The greatest length of the Navicul&, according to the
author, 2th of a line = 0°0492 millim. (according to the
figure only 0-022). To this I believe I ought to refer a
specimen I collected at Trieste, the Navicule of which
attained 0°05 in length, and 0:009 in breadth, as well in
the primary linear, as in the secondary elliptico-acute
surfaces. r

44.4 ANIMAL NATURE OF DIATOMEE.

The partial tubes are very evident, and so is their
confluence at the apex, from which is derived the digitato-
multifid ramification.

Schizonema apiculatum, Ag.

The Zth of a line, which Kützing assigns as the length
of the Naviculs, correspouds to 0:0492 millim. As usual,
the figure gives a measurement of half the size. In speci-
mens from Lenormand and Brebisson, I find the length
of the Naviculae 0°04 millim., the breadth of the primary
surfaces 0°01, of the secondary 0'012, and the figure of
both perfectly corresponding with the description and the
delineation of Kützing.

Schizonema medusinum, Kütz., (Micromega.)

In specimens so denominated by the author, I find the
Naviculze 0°036 millim. long, 0°0047 broad in the primary
surfaces, and a millimillimetre more in the secondary.
Kiitzing does not state the dimensions; from his figure,
I infer the length only to be 0°0262, and the breadth in
proportion.

Schizonema chondroides, Kütz., (Micromega.)

I regret that I have been unable to study this species,
on account of the peculiar mode of prolification at the
extremities,

Schizonema spinescens, Kiitz., (Micromega.)

Found in Venice, by Zanardini. The Naviculs (0-042
millim. long, and 0:0062 broad,) differ little from the
dimensions indicated by Kützing (th of a line), being
about twice the size of the figure (9°6 millim. +3? = 0:022).

ANIMAL NATURE OF DIATOMER. 445

Schizonema albicans, Kütz., (Micromega.)

If the specimens from Dalmatia, which I think ought
to be referred to it, really belong to this species, the
name is not well chosen ; indeed it indicates a condition
which the author confesses not to be constant, (vel
olivaceo-virescens) and which is common to many species
in a state of decay. Length of Navicule 0-036, (Kützing
says „th of a line = 0:03 millim., and figures them
6 millim. = 00142), the breadth of the primary surfaces
0:0061, of the secondary, which are broadly elliptical,
it is a millimillimetre more.

Schizonema torquatum, Harv.
(Micromega polyclados, Kütz.)

It is on Kützing’s authority that I refer to his species
the authentic specimen which I received from Berkele
with the name above mentioned. In this I find the
length of the Naviculze 0:03 millim., and the breadth 0-005
in the lateral surfaces, which exceed the primary by a
millimillimetre. The dimensions, therefore, (not described
by Kiitzing,) are something less than twice those of his
figure. Kützing is right in remarking that my Schizonema
nebulosum, which I erroneously considered belonging to
the genus Frustulia, corresponds to this species in the
form and dimensions of the Navicule. Although when
dried upon paper it only forms a light cloud, yet, when
diligently examined, it proves similar in ramification to
Harvey’s species.

Schizonema pallidum, Ag., (Micromega.)

In a specimen gathered by me at Trieste, and corres-
ponding perfectly with the description and figures, I find
the greatest length of the Navicule to be 0:04, whilst
Kützing says it is 3th of a line = 0'049 millim. The

446 ANIMAL NATURE OF DIATOMEM.

breadth, both of the perfectly linear primary, and the
elliptico-elongate secondary surfaces is about 0008. We
shall find a perfect agreement with Kützing’s figure by
supposing, as usual, that it represents one half of the
indicated amplification of 420 diameters, the Navicule
being here 8°5 millim. long.

I believe that some specimens, also collected at 'Trieste,
by Zanardini, (which are perfectly similar to the preceding
in external appearance, but of which the Navicule are
shorter and more slender,) belong to a different species,
not described by Kiitzing. In the one, the length is five
times the breadth; in the other it is six times in respect
to the secondary surfaces, and more than eleven times in
respect to the primary. Length 0:036; breadth of the
primary surfaces 0°006, of the secondary, 0-0035 millim.

Schizonema corniculatum, Ag., (Micromega.)

Although I might be supported by Kützing in the
determination of this species, and though my specimens
perfectly agree in external appearance with the figure
given by this author, stil I cannot but confess some
doubts as to the species itself. And, in the first place,
Kiitzing attributes a larger size to the Navicule than to
those of the preceding species. He says they are no less
than 3th of a line, therefore 0:054 millim., and in con-
formity to this he represents them 1'1 millim., with an
amplification one half less than what he assigns tohis figure.
On the other hand, I find the greatest length 0°03, and the
greatest breadth, whether of the exactly linear primary
surfaces, or of the elliptico-elongate secondary, 0-007.
The length being rather more than four times the breadth,
the form of these Navicule corresponds with that re-
presented by Agardh (Icon. Alg. Europ., tab. 4.) I find
that the figure given by Agardh himself does not corres-
pond with it in external appearance; the figure agrees
much better with the preceding species.

It is true that we can find this form more or less rich

ANIMAL NATURE OF DIATOMER. 447

in penicillate branches, which would seem to justify the
opinion of Kiitzing, who regards the Micromega penicil-
latum of Agardh as a variety of the same species, but
without noticing whether the Schizonema penicillatum,
Chauvin, should also be placed there; but the same speci-
mens more denuded have no resemblance to Agardh’s
figure. For this reason, before I consulted Kützing,
and before he published his work, I had given the name
of Micromega divaricatum to the one I had collected
very abundantly at Zava.

Schizonema Blyttii, Ag., (Micromega.)

The following species are ascribed by Kiitzing to the
preceding genus.

Schizonema minutum, Kütz.
Schizonema humile, Kütz.
Schizonema araneosum, Kütz.
Schizonema comoides, Ag.

I am indebted to the celebrated Berkeley for an oppor-
tunity of studying this species, and of convincing myself
of the existence of special tubes, which easily escape
observation, owing to their own tenuity and the size of
the Navicule, whose uninterrupted series are narrowly
stipate. Itis by these characters, and by the form and
proportion of the Navicule themselves, that I was led to
the exact determination of the species, though the dimen-
sions are very different from those indicated by Kiitzing.
He says the Navicule are as much as 4th of a line in
length, or 0°049 millim., (and he represents it, with a
power of 400 diameters, 8°9 millim., which would be about
half the size indicated,) and I, again, found it no more
than 0:024 in length, 0°005 in breadth of the secondary
(gu. primary ?) surfaces, and very variable in the always
broad secondary surfaces, which attain to 0'012 millim.

448 ANIMAL NATURE OF DIATOMEE.

Schizonema floccosum, Kütz.

If, as seems probable, there exist partial tubes in this
species, and we ought therefore to retain it in this genus,
it is necessary to change the specific name, for there 1s
already a Schizonema floccosum of Rudolphi. By the
customary laws, we ought to name it S. Kützingit.

Schizonema crispum, Montag.
Schizonema plumosum, Kütz.
Schizonema capitatum, Kütz.
Schizonema trichocephalum, Kütz.

I find a Schizonema, from Marseilles, with which I was
favoured by Solier, and in which the Navicula are 0:025
in length, to correspond exactly with the definition and
the figure of Kiitzing. He says they are as much as %
of a line = 0°0225 millim. There are evidently partial
tubes, and the figure of Kützing leads us to suspect their
existence.

Schizonema Bryopsis, Kitz.
Schizonema Arbuscula, Ehrenb. (Naunema.)

Although Ehrenberg asserts that there are no partial
tubes, still he admits that this species forms a transition
to the genus J/ieromega. Kützing’s figure, by analogy
with other species, induces us to admit their presence.

Schizonema hydruroides, Kütz.

I cannot help observing that Kützing, the most acute
observer and most faithful painter of nature, has in this
species also clearly delineated the special tubes, though
he has placed it in the genus Schizonema.

ANIMAL NATURE OF DIATOMER. 449

Schizonema Smithii, Agardh.

The testimony of Kützing, and a comparison with an
authentic English specimen, obligingly supplied by
Berkeley, convince me that the Schizonema which we
have most abundantly of all in the Lagunes of Venice,
belongs to this species. I was led away before from this
conclusion by the exclusive locality of Sidmouth, indi-
cated by Kützing, and the comparison of specimens with
which I was favoured by Harvey, of which we shall speak
by and by, by the difference of measurement, and the
evident presence of partial tubes. Kützing says the
length of the Navicula is 3th of a line, or 0-054, and, as
usual, gives a figure less than half the size he mentions,
(— 1-1 millim. (#2) = 0-026.) I find the greatest length
to be constantly 0°044, the breadth of the secondary
elliptico-elongate surfaces 0-012, and that of the primary
slightly elliptico-truncate 0012. As to its generic posi-
tion, I observe that Harvey places this species in his
section Schizonema, corresponding to the d/icromege of
Agardh and Kiitzing.

Finally, though incidentally, it is right to make a
remark here on the practice, with even the most con-
scientious authors, of copying references without verifi-
cation. Both Harvey and Kiitzing copy from Agardh
the reference to Ulva fetida of English Botany (pl. 2101),
whilst in that classical work there is only the Conferva
fetida, and the Ulva fetida of Vaucher is merely cited,
by mistake, as synonymous.

Schizonema sirospermum, Kütz., (Micromega.)

Though not appertaining to this series, I here advert
to this species, because the specimens just mentioned,
with which I was favoured by the celebrated Harvey
under the name of 8. Smithii, belong to it. Kützing
informed me that he had received them, without a name,

29

450 ANIMAL NATURE OF DIATOMES.

from Ralfs, and that he had named them as above. ‘To
him, therefore, I leave the description. Length of
Navicule 0:0337 millim.; breadth of the elliptico-elongate
secondary surfaces as much as 0'007; that of exactly
linear primary surfaces 0:01. In this species I clearly
saw the so-called internal spermatia, in form at first
ellipsoidal, afterwards globose, varying in diameter from
0-028 to 0:05, furnished with a double envelope, within
which the internal granules grew gradually in size.
Similar in external appearance to Kiitzing’s figure of the
following species.

Schizonema helmintosum, Chauv.

The specimen with which I was favoured by Berkeley
corresponds perfectly with the figure and description of
this species given by Kützing, varying a little in the
assigned dimensions of the Navicule. Length 0'052
millim., (Kützing says 3th of a line = 0°54; he figures it
1:1 2” 0-26 millim.,) breadth of the elliptico-truncate
primary surfaces as much as 0:008, and of the elliptico-
rotundate secondary 0'012; less, therefore, than one third
of the length, which is the proportion indicated by Kützing.
In this species I have never been able to see the central
perforation with distinctness. As to the delicately crisped
fibres, described and figured by this author, I have
assured myself that they are nothing more than the
margins of thick partial tubes.

Under the same name of Schizonema helmintosum, and
with the indication of Chauvin (Ag. de la Norm., Fasc. IV,
No. 77), I received from Lenormand a Schizonema from
Calvados which differs very much from the preceding in
the dimension of the Naviculee, though very similar to it
im external appearance and in the forms of the Navicule.
These are 0°32 long, and 0:007 broad. As in other
species, there are mixed among the larger Navicula,
others smaller, some very small. Hence we may suspect
that the English species do not exactly correspond with

ANIMAL NATURE OF DIATOMER. 451

the French. We are induced to form this opinion by
the observation of Harvey, “The frustules are larger
than in S. Smithii, longer. and blunter, double, and
rather densely set.” This is applicable to the specimen
from Berkeley, but not to this one of Chauvin, which
ought to be authentic.

Very different, both in external appearance and in the
extreme tenuity of the threads (f/), is another Schizo-
nema, also from the Coast of Calvados, obligingly supplied
by Lenormand, with the name Schizonema helmintosum
var. Chauv., in which the Naviculz are 0:0185 in length,
and 0'006 in breadth, as well of the exactly linear
primary surfaces, as of the elliptical secondary. The
partial tubes embrace the navicular series closely, and
frequently after, when the Navicule have escaped,
contract into fine threads or become deformed and
wasted.

Schizonema laciniatum, Harv.

I received specimens of this beautiful species from
Harvey himself, and found the Navicule 0'027 long,
and 0°007 broad, in the primary surfaces, which are
almost exactly linear, and in the elliptico-rotundate
secondary 0:0065. This agrees with Harvey’s observation
“ Frustules very minute and exceedingly numerous.” This
would seem to refer to a species different from that de-
scribedand figured by Kützing, with thename S. scoparium,
in which he says the Navicula are jth ofa line in length
= 0'054 millim., and to which he assigns as an uncertain
synonym this of Harvey, and the $. Smithii of Mrs.
Wyatt, (Aly. Danm. No. 151), which, according to the
indication of Harvey, would rather seem to belong to the
one before mentioned as S. sirospermum.

Schizonema mucosum, Kütz.

From Kützing’s figure we should be induced to suspect
the presence of partial tubes in this species also. As to

452 ANIMAL NATURE OF DIATOMEA.

the synonym of Agardh (8. ¢enwe), it seems more easy
to suppose that some mistake may have occurred in the
denomination ofa specimen, though received from the
author himself, than to suspect so incorrect an observation
as would result from the description and figure of this
his own species given by Agardh, (Jcon. tab. 3.)

Among the species ascribed to this genus or sub-genus
by Harvey, two remain still to be mentioned.

Schizonema obtusum, Greville.
Schizonema Wyattie, Han.

We ought, finally, to add some species which we could
not possibly include in any of the preceding.

Schizonema Stalianum, Mgh.

S. parasiticum, lubricum, viride vel viridi-rufescens,
fjilis setuceis, longe productis, apice attenuatis, irregula-
riter ramosis, ramis divergentibus brevibus ; naviculis arcte
seriatis mediocribus (0°03), longitudine latitudinem sex-
tuplo superante, e facie ewacte linearibus, e latere elongato
ellipticis ; parum angustioribus obtusiusculis.

Sig. Stalio sent me specimens of this species, found at
Lesina, in Dalmatia.

It attains the length of three or four centimetres, is
very mucous, and adheres strongly to paper. ‘The threads
(fli) attain almost a decimillimetre in thickness near
the base. It resembles none of the before-mentioned
species in external appearance, except the &. kelmintosum
var. of Chauvin. The partial tubes are very slender,
but distinct. Kützing, to whom I sent it, acknowledged
that it was new.

Schizonema papillosum, Mgh.

S. parasiticum, pumilum, mucosissimum, viride, fits
ultra selaceis subsimplicibus vel ramulis spiniformibus

ANIMAL NATURE OF DIATOMER. 453

acutis ornatis, papillis minutissimis regulariter dispositis
omnino tectis; naviculis arcte seriatis mediocribus (0'0264)
longitudine latitudinem fere quadruplo superante, e facie
leviter elliptico truncatis, e latere anguste ellipticis, obtusi-
usculis.

Sig. Botteri sent it from Lesina to his friend Zanardini,
by whom it was communicated to me.

It scarcely attains two centimetres in length; the
threads are about two decimillimetres in thickness, the
colour dark green. The greatest breadth of the primary
surfaces is rather less 0'007 ; that of the secondary
00043; the papille appear hemispherical or slightly
conical; they are 0°0007 in height, and are arranged
in a quincunx.

Schizonema Corinaldi, Mgh.

S. parasiticum, pumilum, viride, filis subsimplicibus
setaceis, naviculis seriatis, minutis (0°016) Jlongitudine
latitudinem fere quintuplo superante, e facie exacte linea-
ribus, e latera anguste ellipticis.

Corinaldi found it at Genoa, and Solier sent it to me,
without a name, from Marseilles.

It is parasitic, like the preceding, growing on Scaphu-
laria scoparia, or upon Polysiphonie, and in like manner
is about two centimetres long. The threads, slightly
mucous, are a decimillimetre and a half in thickness.
They are usually simple; the few ramifications are short
and divaricate.

Schizonema Zanardinii, Mgh.

S. tenuissimum, pallide virens, filis capillaribus in ramos
arachnoideos corymbosos monosiros sensim solutis, naviculis
laxe seriatis mediocribus (0'025), longitudine latitudinem
quadruplo superante, e facie exacte linearibus, e latere
elliptieis.

454 ANIMAL NATURE OF DIATOMER.

(Schizonema, Sp. nov. Zan. in lit.)

Zanardini found it plentifully in the Lagunes of Venice.
Form: globular tufts, of three or four centimetres in
diameter, which, dried upon paper, form an uniform spot,
in which, by a lens only, the separate threads can be
distinguished. ‘Though Kützing assured me that this
was a new species, yet by its mode of ramification it
resembles 8. flagelliferum.

This long speciological discussion may to some appear
misplaced, or at least at variance with the proposed plan
of this essay, intended as an organographical and physio-
logical examination of the genera. The principal ground
of my defence is the great importance of Kiitzing’s most
valuable work, and the respect that is due to so great an
author. Who would dare to subject so immense a
collection of most delicate observations to critical exami-
nation, unless he were able to counterpoise them with a
series of his own observations, if not equally numerous,
at least sufficient to prove the critic in possession of
means and practice, and diligence and honesty of ob-
servation? Such has been my object, and if I have erred
im any respect, for I must admit that it is easy to err in
such minute researches, I hope, notwithstanding, to have
demonstrated both the excellence of the instrument
expressly made for me by Amici, of which I am sure
that no one possesses its equal, Mohl only excepted, and
the good intentions by which I endeavour to prove my
gratitude to the most gracious Prince who bestowed
upon me so munificent a gift. I believe, too, that an
examination of various specific forms is necessary, that
we may deduce from them some considerations as to the
organology of the genus.

The presence of minute Naviculz among the larger, to

ANIMAL NATURE OF DIATOMER. 455

which we have adverted in many species, seems to me to
prove—what might easily be deduced from the ob-
servations of Kiitzing—that the so-called Spermatia are
developed within the fronds, if we may use an expression
taken from the vegetable kingdom. I could never per-
ceive that these smaller Navicule were included in
distinct tubes, or that they constituted an uniform series
in the order of their size. It seemed, rather, to be con-
stantly the case that they were dispersed through the
tubes of the larger ones. From this it seems that we
may conclude that when the spermatium is mature, when
its envelopes are broken up and about to be reabsorbed,
the young Navicule, passing from tube to tube, are finally
dispersed. And continuing to supply the want of sufficient
observations by induction, we may suppose that these do
not begin to divide until they have attained their greatest
dimensions. It then becomes intelligible how the partial
tubes originate, through the persistence of the thin external
membrane, which we know, by preceding observations,
manifests itself distinctly whenever the deduplication
takes place. Only we must suppose that the silica is re-
absorbed, while the membrane remains in Monnema,
on the contrary, it disappears. It is most important to
observe how these series of Navicule are formed within
the proper tubes. It is, in fact, the result of observation
that their disengagement is always effected in the plane of
the primary surfaces. ‘The series may present either the
primary or the secondary surfaces. In either case the
Navicule may be found arranged one behind another,
either contiguous or more or less apart. ‘They are some-
times imbricated with the primary, never with the se-
condary surfaces; and when the imbricated series is
viewed on one side, the Navicule present themselves
with their secondary surfaces entirely free and inclined
obliquely. Therefore we must suppose, so soon as the
deduplication (sdoppiamento) has taken place, the two
new individuals, rotating upon one of the sides of their
surface of contact, as upon a hinge, represent, in some

456 ANIMAL NATURE OF DIATOMEE.

manner, a box which opens, and the two primary sur-
faces coming into contact, the disengagement or separa-
tion becomes more or less complete. If these deduc-
tions be legitimate, as to me they appear to be, the
result is that the successive growth of the entire frond
is due to a dowhle element; the elongation of each series
by incessant deduplication, and the intercalation of new
series between those that pre-existed. ‘The comparative
examination of the extremities is important in respect
to the elongation. In various species the single partial
tubes tend to detach themselves from their reciprocal
union, either uniformly from the base (/flagelliforme,
medusinum, Zanardinti), or merely towards the summit,
in a sort of fan-shape (kelmintosum, lacinatum). Again,
we find the multiplication of the series principally
effected near the apices, aud accomplished more quickly
from the elongation of the pre-existing ones, on which
account the extremities are clavate (Arduscula, clavatum.)
Where these two processes advance, part passu, the re-
sulting extremities are obtuse (patens, Bryopsis, intri-
calum). Where the elongation of the first series always
precedes the appearance and formation of the new ones,
the apices are acute (floccosum, Kütz. ramosissimum,
Hyalopus, araneosum, Smith, torquatum). It is cha-
racteristic, too, of some species (chondroides, trichocepha-
lum, capitatum, corymbosum, spinescens), to have the
prolification terminal, which manifests a succession of
distinct periods of vegetation. Finally, the particular
condition of the S. myaacanthum demoustrates a contem-
poraneous elongation of the series, which the resistance
of the external envelope compels to flow towards the
apex, until, that resistance bemg overcome, a palmate
disposition of the branches is produced.

As to the Naviculee, we know still less of them than in
the preceding genera. Ehrenberg says that some of them
are striated, but this is not confirmed by Kiitzing, nor
have I seen striz in any species. Yet in some I have
seen the two longitudinal lines of the primary surfaces dog-

ANIMAL NATURE OF DIATOMEM. 457

which are considered to be canals. I have not been
able to see the median aperture, which Kützing describes
and figures in some species (/elmintosum). As to the
distribution of the internal substance, though nothing
positive can be deduced from the observation of specimens
dried and softened, or even preserved in. alcohol, it is
yet remarkable that even in such a state it presents
different conditions that are constant in each species. In
most instances it is collected along the central part of
the lateral surfaces, so that it exposes a colourless longi-
tudinal area in the centre of the secondary surfaces, and
only the two extremities of the primary surfaces are
colourless. Sometimes, too, the median line of these last
is colourless, because the colouring matter is lodged
(niechiata) in the four inner angles. It is not unusual
to find it condensed in a~single central globe. In a
few species only I have seen it constantly divided into
two portions corresponding to the extremities, whilst the
median area of the entire body of the Navicule remained
uncoloured.

44. Dickızıa.— Phycoma foliaceum (phylloma) basi
substipitatum. Navicule in membrana gelinea irregu-
lariter sparse.

Kützing does not describe the structure of the so-called
membrane of the only species (D. ulvacea) of this genus,
and I am sorry that I cannot consult Berkeley’s descrip-
tion. This membrane may be formed of cells including
the Naviculz, as in Frustulie, or of elongated cells or
tubes, as in Schizoneme, or of a single capacious flattened
cell comparable to that in Monneme ; or, finally, this so-
called gelatinous substance may be a mass entirely con-
tinuous, in which the Navicule may be immersed, as
indicated by Kiitzing “ in der gallertartigen Haut einge-
bettete,”” as we have suspected of some species regarding
which there seems to be a doubt whether they belong to
the Monneme& or the Schizonema.

‘Nhe last seven genera, (Frustulia, Berkeleya, Raphi-

458 ANIMAL NATURE OF DIATOMES.

lea, Homeocladia, Schizonema, Micromega, and Dickica)
constitute the group of Schizonemex. The substance
which surrounds and includes the Navicule in these
genera, which seems to be the same as the peduncle in
Achnanthides, Podosire, and many other genera, is termed
jelly (gelinea), by Kiitzing, who, under this denomination,
compares it to that of the true Alge. The observations
adduced in the preceding memoir confirm the absence
of nitrogen, and its ternary composition. Now we know,
from the observations of Schmidt, Loewig, and Kölliker,
that a similar substance, destitute of nitrogen, ternary,
insoluble in caustic potash, and isomeric with starch, con-
stitutes the external coriaceous stratum in the Ascidia,
simple and aggregate, and forms the gelatinous mass in
which groups of individuals of compound Ascidia are
lodged. These authors found that the presence of this
substance is a character common to all the Tunicata,
and it is supposed that the Doliolum mediterraneum
ought to be placed in the same family from this
character. This discovery, which I before supposed
possible, has therefore now entered the domain of science.
As the presence of a quaternary azotised substance is
no exclusive character of animal nature, so the pre-
sence of a ternary non-azotised substance, isomeric with
starch, is no more an exclusive character of a vegetable
nature.

With respect to origin and formation of this substance,
it is undecided whether, as Kiitzing asserts, we are to
regard it as a product of secretion, or rather as existing
per se. All animal secretions are formed in the same
manner. The theory of Goodsir, Bowman, Henle and
Mandl has recently received confirmation from the labours
of Lereboullet on the biliary vessels of the Aselli and
those of Gros on the production of butyraceous vesicles
on the internal surface of the mammary utricles. It is
now proved that whatsoever the animal secretions may
be, they are effectuated by a production of new cells on
the secreting surface, and the accumulation of liquid

ANIMAL NATURE OF DIATOMER. 459

which penetrates within them by endosmosis through the
double wall dividing their cavity from that of the pro-
ducing cell. When these vesicles become detached, they
either maintain a life of their own, as in the epidermis
and its productions, or they burst and pour out their
contents. If such be the origin of the gelatinous sub-
stance enveloping the Schizonemez, we must allow that
the secerning surface is either external or internal to
some particular organ. And these little cells, invisible
from their minuteness or tenuity, may continue to live,
or at least to pour out their contents, before or after
they issue from the secerning organ. But all this is
hypothetical, and wanting in any support of observed
facts. Again, considering the history of the successive
development of Diatomacez, it is more probable to
suppose the possible permanence, extensibility, and pro-
gressive growth of one of the embryonal tunics, of which
we have numerous examples, were there no other, in all
animals that undergo metamorphoses.

The Schizonemeze and the other seven genera (Navicula,
Amphipleura, Ceratoneis, Stauroneis, Amphiphora, Am-
phora, Diadesmis), before mentioned, constitute the great
family of Naviculee. The Naviculez, says Kützing, when
treating of their affinities, very much resemble individuals
of the preceding families, with which they were formerly
confounded ; but they are to be distinguished as well by
the central aperture of the two lateral surfaces as by the
regularity and symmetry both of these and the primary
surfaces. He says, on the other hand, that this aperture
is frequently absent, especially in the Schizonemez, or at
least escapes observation by its minuteness. Now I add
that we have this same regularity and symmetry of form
in the Synedre, and, with few exceptions, in all the family
of Surirellew. So that there is good reason for inquiring
what essential character remains to distinguish the
Naviculex? The consideration before adduced with re-
gard to the origin and nature of the investing substance
in Schizonema would seem to me to furnish some reason

460 ANIMAL NATURE OF DIATOMER.

for bringing hither the affixed Synedre, in a physiological
point of view, only that this union would be one of
analogy rather than affinity, inasmuch as we find corres-
ponding conditions in almost all the families. It is
still true, as Kützing observes, that here the included
are the prevalent forms, occurring with the free and
naked forms, whilst the linear association is only re-
presented by one genus Diadesmis, and: the stipitate
forms and cateniform associations are entirely absent.
But, with respect to the morphological signification of
this predominant inclusion, I am far from agreeing
with Agardh and Kützing in regarding it as indicating
a higher organisation. In the theory of Agardh, where
every inferior being represents an elementary organ of
superior beings, the mere aggregation of many individuals,
which, taken together, form one collective individual, is
sufficient to mark a step towards organic superiority or
perfection. But we have too many examples of similar
aggregations even in the lowest members of both organic
kingdoms to satisfy ourselves with this character of
complication. It is not the mere aggregation of organs,
but rather their mutual concurrence in the formation
of new organic assemblages (congegni) that establishes
the superiority in plants, as well as in animals. For
this reason the Annelidse are the lowest among the Arti-
culata, even whilst the number of joints, all equal to
one another, of which they are constituted, is indetermi-
nate. For this reason I believe that the opinion is well
founded which regards Synpetalous flowers as superior
in organic complication to the Dialypetalous, as the flower
in general is the most complicated apparatus of the plant,
like the head ofan animal. And without wandering from
the question into extraneous digression, I shall content
myself with recalling to memory what I have intimated
before in relation to the involving substance, to sustain
the opinion that the included forms are to be regarded
as inferior to all the others; and the affixed, stipitate,
and concatenated, as intermediate between these and

ANIMAL NATURE OF DIATOMEER. 461

those that are free; which last, conditions being equal,
are superior to all the rest.

Regularity, then, and symmetry of form appear to me
characteristic of inferiority, nor do I consider new argu-
ments necessary to maintain a principle which is univer-
sally adopted in all natural classifications.

Iam sorry to repeat here what I have said so often
already, that we are entirely wanting in true data to judge
of the affinities of Diatomeze, among themselves as well as
with other beings, and of the degree of their organic
complication ; for we are completely ignorant, as it were,
of what this organisation is. And as to this, Kiitzing
only informs us that the internal substance, which he
terms gonimic, extends itself in a thin strip (/ettuccia)
along the secondary surfaces, then divides itself trans-
versely in the middle, and finally contracts itself into one,
two, or rarely more globular portions (grumi). We have
already found contrary to the opinions of Ehrenberg,
some more important particulars respecting the Navicule.
Nor have we anything different to add, generally, as to
all the family. :

The Naviculee, together with the two preceding
families (Cymbellee and Gomphonemez), constitute the
group of Distomatice, a group characterised solely by
the organic condition indicated by the name, and, which
we have so often found to be wanting.

The other two families (Cocconoidez and Achnanthez)
which, comprehended under the name of Monostomatice,
constitute, in union with the preceding, the grand division
of Stomatice—appear to be much more nearly allied.
The entire system, I am obliged to repeat, is constructed
upon isolated and inconstant characters, and on that
account cannot fail to be vacillating. But it is equally
necessary to allow that, in the actual state of science
it would have been difficult to do better; and we must
also regard it as a principle suggested by sound reasoning,
to attribute great importance to the presence or absence
of the central aperture in one or both of the secondary

462 ANIMAL NATURE OF DIATOME.E.

surfaces, for that condition ought to be referred, of
necessity, to important peculiarities of internal structure.
And therefore it becomes difficult to conceive how the
exceptions can be so numerous as to render this cha-
racter so insufficient for classification.

The Stomatice, together with the Astomaticae, of which
we have already spoken, constitute the great order of
Striated Diatomez, which is proportionally, much more
extensive than the two following.

45. Popospurnta— Bacilli a latere primario cuneati
a latere secundario obovato-lanceolati, afixi. Stipite nullo
(vel obsoleto).

With this genus commences the order of Diatomez
furnished with Vitte, or internal prominences, which
divide the cavity of the shield more or less incom-
pletely into distinct chambers ; and here, too, commences
the family of Licmophorez, in which is reproduced the
cuneate form of the Gomphonemez. This genus repre-
sents, in the Licmophorez, the genus Sphenella of the
Gomphonemex, for, like that, it is distinguished from
other genera of the same family by the more or less
complete absence of the stipes. The obovato-lanceolate
figure of the secondary surfaces is precisely that of the
Sphenelle and of the Gomphonemez in general. The
cuneate form of the primary surfaces is, in Podosphenia,
always more dilated at the summit and acute at the base,
so that they resemble a triangle more than a trapezium.
Of the nine species described and figured by Kiitzing,
only one (P. Ehrenbergii) presents transverse strie on
the secondary surfaces. The essential character of
Gomphonemez, the median aperture in both secondary
surfaces, is absent.

They present also the character of Vitte. But if we
carefully examine these vittae, they are merely the same
longitudinal lines which run along the primary surfaces
of almost all the preceding Diatomex, the same lines
which in many cases are produced by distinct canals

ANIMAL NATURE OF DIATOMEE. 463

furnished with terminal perforations. And here let us
not forget how these canals evidently project into the
cavity of the Melosires, forming more distinct vittee than
others ever do; on which account, if we ought really to
found on this character the distinction of orders, the
family of Melosireze or the genus Melosira at the least,
ought undoubtedly to be referred to the order Vittata.

46. Ratprpornora.— Bacilli a latere primario cuneati,
altero latere obovato-lanceolati, stipitati.

We encounter the same difficulty in distinguishing
Rhipidophora from Podosphenia that is experienced
when practically applying the generic distinction estab-
lished between Sphenella and Gomphonema, and in all
other similar cases (Cymbella and Cocconema, &c.) ; these
differ only in the stipes, which is very variable in length,
and not always entirely wanting in the first of these
two genera.

The large size of some among the fourteen species
enumerated by Kiitzing permits us to observe clearly
the conformation of the shield. Let us suppose a cylin-
drical articulation of Melosira,and so compress it unequally
on one of its sides, and in the direction of both pairs of
opposite surfaces, that the resulting form shall be cuneate,
and the two incomplete diaphragms formed by the
internal prominence of the longitudinal canals shall
extend, like these, and lose themselves towards the pointed
extremity which forms the base. Such is the structure
of Podosphenia and Rhipidophora. Viewed on one side,
that is on the lateral surfaces, they present an obvate
arch (fornice) marked on the periphery of the surfaces
themselves. And the margin of this arch is thickened
by the presence of the canal, which, seen in front, presents
in the curve its brightness, with an appearance of
perforation.

It would be important to ascertain how the dedupli-
cation takes place. Whenever one of the frustules,
(Bacilli) separates into two, one of the vitte previously

464 ANIMAL NATURE OF DIATOME.T.

existing remains, and a new one appears in the in-
ternal side. Does the formation of the new vitta
precede or follow the median deduplication? I
have not made such observations as enable me to
decide, but it seems to me that the former is the
case.

And the distribution of the internal coloured substance
bears a great resemblance to that of Melosire, especially
in a state of desiccation.

As to the stipes, as well in this genus as the next one,
I have to repeat what has been said of Cocconema.

47. Licmopuora. — Bacilli flabellati a latere pri-
mario anguste cuneati, altero latere lineares basi et apice
rotundati. Stipes crassus rigidus.

The resemblance of this to the preceding genus is only
apparent. But a true affinity connects Lzcmophora to
Synedra, from which it only differs by that character
which, though regarded as essential to the Meridiez is
found very inconstant in Fragillariee and reappears in
many species of Surirella. 'The vittee, in Licmophora, are
not to be compared with those in RAipidophora. "They
are nothing more than the usual longitudinal canals
projecting into the cavity, by which the apparent per-
forations or sections of their cavities appear very near
the margin of the summit. The distribution of the in-
ternal coloured substance is different from that in the
two preceding genera, and greatly resembles that of
Synedra.

If we compare these with the sections Zudularia
and Grallatoria, we cannot at all recognise the alleged
affinity.

For this reason, I think we ought to exclude the
Licmophora divisa from this genus, and place it in the
preceding one.

The four species that remain, (ulgens, radians, flabel-
lata, Meneghiniana,) though described and figured by
Kiitzing with so much diligence, are very difficult to

ANIMAL NATURE OF DIATOMER. 465

distinguish, owing to their great variability in size and
proportion, on which account, too, their form is very
inconstant.

48. CurmacospHEenta.—Bacilli a latere primario
cuneatt, vittis longitudinalibus moniliformibus, altero
latere obovato-lanceolati, disseptis transversalibus in
loculos divisa.

The two species contained in this genus (C. australis,
C. moniligera), have nothing in common except the
moniliform vitte. But in what these really consist we
cannot ascertain from the figures. In the first, Kiitzing
does not delineate the secondary surfaces, and from the
figure any one would say that he had drawn a Synedra.
The second, again, resembles a Podosphenia.

After this analysis of the family of Licmophores
(Podosphenia, Rhipidophora, Licmophora, Climacosphenia),
we can only repeat what has been said of the first two
genera. And as, in our opinion, we ought to exclude
from it the genus Licmophora and unit this to the
Surirelleze, it will also be right to change the name of
the family. ‘Thus limited, it will remain allied to the
Gomphonemez more than to any other. As to the
so-called interanea, we have already recorded their
arrangement in distinct globular masses as in Melosira.
Ehrenberg, treating of Podosphenia, says that this organic
condition is peculiar to young individuals ; and he says he
can distinguish, in the midst of the others, two of these
globules, which he regards as representing the male organs.
He asserts that, im some species, he has also seen the
gastric cells. But when they grow old, Ehrenberg him-
self says that this internal substance accumulates in a
central mass, which is frequently radiated. Kiitzing, again,
describes the internal substance as disposed in two strips
(fettucce), applied to the primary surfaces, which divide
themselves transversely into two or more parts, and finally
resolve themselves into globules. But he certainly must
have taken these particulars from the genus tt

4.66 ANIMAL NATURE OF DIATOMER.

50. SmriareıLa—Bacıli tabulati longitudinalter
viltati; vitte pervie numerose dense stri@formes, stipes
lateralis.

Though the only species of this genus (S. unipunctata),
is common in the Adriatic, I confess myself unable to
form a clear idea of its structure. The complication it
presents in external appearance, and which is reproduced
in the figures of Kiitzing, seems to proceed from vitte of
the surface opposite to the one observed shining through;
there result from this, vittee, strongly and faintly marked,
alternating with each other. Does each one of these
vitte include a canal? And how far do they project
into the cavity? The singular condition described and
figured by Kützing of smaller tablets (Zavolette) attached
to larger ones, indicates a peculiarity of development,
which has no analogy in the remainder of the class.

51. Tesserna.— Bacilli late tabulati, non concatenati,
dense longitudinaliter vittati; vitte medio interrupte
alternantes, stipes nullus ?

This genus, too, is reduced to a single species (7!
interrupta), and, therefore, it is impossible to judge of
the value of the characters that distinguish it from the
preceding or the succeeding, whilst we do not know the
organic importance or the true structure of the vitte.
The breadth of the tablets is remarkable, being five times
more than the length. ‘There is frequently an absence
of a few vitte, accompanied at the same time by a
deformity or derangement of those contiguous. It
appears that this condition precedes the deduplication,
but we have no observation in point. It still remains, also,
to determine the figure of the lateral surfaces.

52. Hyatosira.—Bacilh tabulati quadrati, concate-
nati lateraliter stipitati, interrupte vittati ; vitte alter-
nantes medio lineolis subtilissimis conjuncte.

At first I was afraid that I was led, by want of skill in
observing, to believe that I could see in the two longer

ANIMAL NATURE OF DIATOMEM. 467

(rectangula, obtusangula) of the four species of this genus
a continuation of the vitta from one margin to the other,
instead of their being interrupted and alternating, as they
are figured and described by Kützing. Continuing my
observations, I succeeded at last in finding one individual
exhibiting to my sight the alternations described. Hence
I became convinced that the latter condition is not merely
inconstant but even the least frequent. The secondary
surfaces, neither described nor figured by Kiitzing, are
elliptico-acute, and on these are inscribed the smaller
concentric ellipses, which mark the margin of the in-
complete diaphragm formed by the nearest vitta.

53. Raasponema.—Bacilli tabulati concatenati late-
raliter stipitati, interrupte vittati et transversaliter
striati; vitte capitate. Strie transverse sinis longitudi-
nales numerosas formantes.

I have only had an opportunity of observing one (R.
adriaticum) of the three species of this genus; and it is
because I must therefore limit myself to this that I can-
not agree to what Kiitzing represents in his description
and figure. He omits to indicate the form of the tablets,
which can only be obtained by observation of the
secondary surfaces, or by a longitudinal section; and it
is entirely from this form that the appearances are derived,
on which the specific distinctions are supported. In the
Adriatic species, the figure of the secondary surfaces is
linear in the centre, and cuneato-attenuated (assottigliata)
at the extremities. The frustules (dzeill), therefore, are
thick in the middle, have laterally the two primary
surfaces strongly inclined together towards the outside,
and are much attenuated in the extreme margin. The
vittze are nothing more than canals projecting into the in-
ternal cavity, and projecting slightly, indeed, at the sur-
face, in the middle, and continuous from one extremity to
the other. In specimens dried and softened again,
the canals themselves include air collected irregularly
into bubbles more or less extended. Hence the appear-

468 ANIMAL NATURE OF DIATOMEA.

ance of interrupted and capitate vitte. The appearance
of four transverse series is produced by the form of the
frustules (daci/z). ‘The transverse strie are continuous
even across the vittee and canals; and it is only by atten-
tion to the slight projection of these, that, in withdrawing
the object by slow degrees from the microscope to bring
different parts into focus, we can see first the strize of the
intermediate spaces and not those of the canals, then the
latter and not the former, and vice versd if the object be
brought near again. They then appear always in inter-
rupted longitudinal series, but sometimes in the inter-
mediate spaces, and sometimes on the vittze; and we can
never see them on both at once. Near the margins, the
difference of surface diminishes, and therefore the strise
appear continuous.

In the figure which Ehrenberg gives of R. arcuatum,
(pl. xx, fig. 8,) the secondary surface is represented
simply elliptico-acute, and the vitt appear entirely con-
fined to the extremity. I suspect this figure to be taken
from the external aspect rather than from direct observa-
tion; and from analogy with our species, I should be
induced to believe that the primary surfaces remain
parallel to each other quite to the attenuation of the
extremities, and, therefore, that the series of the apparent
vittee becomes double rather than quadruple.

‘The four genera, (Striatella, Tessella, Hyalosira,
Rhabdomena,) which constitute the family of Striatelles,
are certainly connected by a great affinity. Still it is dif-
ficult to determine their mutual relations, or the connexion
of the entire family with others. Kützing places the
Striatellee in comparison with the genera Fragillaria,
Diatoma, and Achnanthes, as they do not specially differ
from the two former except in the abundance of vitte, to
which, I believe, the two usual longitudinal canals are
correspondent. From Achnanthes they differ as well in
form as in the absence of a central aperture. We will
compare them with the next family when we have treated
of it, contenting ourselves at present with intimating that

ANIMAL NATURE OF DIATOMEA, 469

they are more closely allied to the Fragillariee than to
any other preceding family.

Kiitzing rightly observes, that the Striatellee are
found indifferently, sometimes free, sometimes affixed. It
seems, however, that they were all originally in the
second of these conditions. Still, in the association of
individuals resulting from deduplication the Striatellez
repeat all the forms of the Fragillarieze. Finally, as to the
interanea, Kützing says they are at first disposed uni-
formly, then collected into small spherules, which become
condensed into a central globe. ‘This last condition is
characteristic of the single species of the genus Striatella.
But with regard to Hyalosira and Rhabdomena, I think it
important to mention the wasting away of the coloured
internal substance into longitudinal strips parallel and
intermediate to the vitte.

54. Trrracycius.—Bacilli late tabulatia infilum arcte
connati, longitudinaliter continuo et arcte vittati; a latere
secundario utrogue apice late rotundati, ventro medio
maxime inflato, stipes nullus.

The presence of vittae solely distinguishes the single
species (Z' lacustris) from Odontidium. The lateral sur-
faces are convex, and traversed by transverse and arcuate
coste. Ihave not seen the straight median costa figured
by Hassall, nor the absence of these costz in the space in
the centre, as figured by Kützing. But because the
median lobe is strongly convex, its plane is different from
that of the lateral lobes; hence, when the cost of one
can be seen, those of the other cannot, and vice versd. I
can in no way comprehend Kiitzing’s reason for enume-
rating this genus among the Diatomee stomatice, except
by supposing that he regarded as a large central aperture
the entire median cavity, which seems to be open when,
observing the lateral surface too nearly, the corresponding
convexity escapes from the field of view. Fragments of
organisms, similar to Zetracyclus, are very common in the
fossil flour of Santa Fiore. "

470 ANIMAL NATURE OF DIATOME#.

55. Taseırarıa.— Bacili adnati obsolete stipitatz,
demum senivoluti, concatenati, interrupte longitudinaliter
vittati ; a latere secundario ventre et apicibus inflati.

The variation of form in the frustules (daeilli) of this
genus is very remarkable. On this account it becomes
so very difficult to distinguish between the two principal
species (7. flocculosa, T. fenestrata) of this genus, com-
mon in fresh water throughout Europe ; and the synonyms
become so complicated and obscure.

Hence Kiitzing rightly sought the limits between the
two species in the fine character of alternate vittee in
T. flocculosa, and opposite vittee in 7! fenestrata. With
regard to these vitte, [ observe that they are alike arranged
in fine striae, which continue without interruption even
where the vittee are alternate. "Their alternation in 7' floc-
culosa is not at all constant, and Hassall, too, makes this
remark.

After a long and attentive observation, I believe I have
convinced myself that the structure of the Zubellariee is
something different from that described and figured by
our author. The primary surfaces have a rectangular
figure ; the secondary are linear, or rounded merely at
the extremities (as I find in authentic specimens of 7°
Fenestrata, from Jurgens), or swollen circularly in the
middle, or at the ends, as seems constant in 7! flocculosa.
It follows that the form is that of a cylindroid, strongly
compressed, or of three smaller cylinders, the central
one larger than the others, united together by parallel
walls, and placed at a distance less than the diameter
even of the lateral cylinders; I never obtained a
sight of any aperture. ‘The internal cavity is variously
divided by incomplete diaphragms. When one only
exists, as is frequent in 7! fenestrata, it is clearly seen to
be furnished with a large central perforation, and to con-
tain a canal, which, running along the internal wall of
the primary surfaces to where the diaphragm detaches
itself, comes to communicate with another similar canal,
hollowed in the free margin of the diaphragm itself. When

ANIMAL NATURE OF DIATOMER. 471

we observe such a frustule (dacillus) on one of its
secondary surfaces, the large central aperture eludes the
eye; still it may be seen, but only across the transparent
surface itself.

In this species we may frequently see two similar
diaphragms. In the 7. flocculosa, as many as nine may
be met with (Hassall). They are not all equally easy to
be seen in specimens that have been dried and softened.
A green substance seems to be coagulated within them ;
and where this is wanting, the transparency prevents our
distinctly seeing either the canals or the diaphragms.

It is a frequent condition of the 7! flocculosa that this
coloured substance is found in one lateral half, and not
in the other, of the same canal; hence the alternating
character of the so-called vitte. So there does not exist
a canal continuous to open extremities, which traverses
the frustules (dacilli), as authors describe and delineate,
but many apertures (/enestre), arranged in a series, in
which bubbles of air remain imprisoned, unable to make
their escape without rupture of the shield.

In the 7. fenestrata, every individual has two diaphragms
when the development is complete. When deduplication
takes place, two individuals are produced, each having
one diaphragm.

The second diaphragm afterwards appears, and, at a
later period, another deduplication. It is still a ques-
tion whether both the new individuals equally divide ;
whether a new diaphragm appears in both or in one
only; whether on the inner or outer side; and whether
among the four individuals resulting from the second
deduplication, those are equally prolific which retain
the primitive diaphragms, or those which have new ones
only,—or both together? In the 7! flocculosa it is rare
to see one diaphragm only; and, again, it often happens
that two contiguous frustules (daci//i) possess different
numbers of them. ‘Therefore, besides the inquiries indi-
cated above, another might be instituted on this species,
—whether or not the deduplication is always subsequent

472 ANIMAL NATURE OF DIATOMER.

to the formation of a diaphragm? a circumstance in
which the essential difference between this and the pre-
ceding species seems to reside.

In the fossil flour of Santa Fiore, besides the 7!
amphicephala, we find many fragments which cannot all
be referred to the two preceding species. The vittae
seem to have disappeared in all, owing to the absence of
colouring matter, and the under-mentioned conditions of
the shield are clearly seen in all.

It is justly observed, by Hassall, that there is a difference,
in the mode of connection, between the two common
species (flocculosa, fenestrata). In the second, there is a
distinct. cushion (cussinetto), in the form of a hinge,
connecting one frustule to another. In the first, the
angles are nearer together, the hinge is wanting, and
there remains in its stead a sort of detached border,
showing that the very fine external membrane has been
lacerated, yielding to the excessive distension, but
persisting partially to maintain the union, and without
retracting itself, as it must do, in the other species, to
originate the hinge.

This diversity of condition appears to me in accordance
with the different period of development at which the
deduplication occurs in the two species, as well as with
the other considerations already mentioned. I think
that we ought to take this fact into account, as also
serving to support my opinion, as to the nature of this
external membrane.

Besides the two living species, and the fossil one just
mentioned, Kiitzing describes another, discovered by
Lenormand; and enumerates three from America, the
discovery of which is due to Ehrenberg.

56. Trrpstnozr.—Bacilli tabulati adnati, obsolete
stipitati, demum semisoluti et isthmo concatenati, vittis
transversalibus ahbreviatis marginalibus (non perviis)
capitatis in latere secundario nodosi.

If we imagine a series of frustules of Zudellaria joined

ANIMAL NATURE OF DIATOMER. 473

together, not laterally, but the head of one to that of
another ; or, in the direction of breadth instead of length,
we shall form the most just idea of the only species of
this genus, (7. musica). And though I could not study
it in the very small fragment with which Kützing favoured
me, I still thinkI can assert that here also, as well as
in the preceding genus, the canals run without interrup-
tion along the attachment and the free margin of the
diaphragms; and the apparently capitate vitte are
produced either by animal matter, or an open space in
those imprisoned canals.

Fragments, similar in appearance to what is seen
laterally in the margins of the frustules of Terpsinöe, are
met with in the fossil flour of Santa Fiore.

57. Grammatopnora.—Bacilli oblongato tabulati,
adnati demum semisoluti et isthmo .concatenati; vitte
longitudinales semper bine, medio interrupte, plus minusve
curvate.

Kützing, treating of G. marina, the most common,
remarks that by calcination the exterior inflexions of the
vittae disappear, and that, on this account, a greater
distinctness is acquired by the canals, in which these
vittze are situated, and which extend uninterruptedly the
entire length of the frustules. He represents these
canals, by two delicate lines, one external, the other
internal, to each vitta, as well in this species as in
all the others. I see the external line clearly, and
to me it seems to indicate the conjunction of the secon-
dary valves with the primary. ‘The striated margins,
seen in many species (fropica, gibba, gibberula, serpen-
tina) belong to the lateral surfaces; and when, as in
G. marina, they are smooth, they turn yellow by the
action of heat, like the remainder of these secondary
surfaces. On account of this colouring, it is difficult
to see the external arches of the vittze, for these lines
run at a tangent to them. I suspect that along this
suture there runs a fine canal, hollowed out in the

ATA ANIMAL NATURE OF DIATOME.E.

thickness of the wall, the cavity of which appears as
a furrow, or rather as a perforation, at the extremities.
The oval aperture (fenestra), which is visible in the
middle of the secondary surfaces, belongs to them in
appearance only, as in the preceding genera, It is only
seen because of the transparency. In Grammatophora,
also, the appearance of interrupted vittze, is produced by
the presence of diaphragms pierced by an ample central
elliptical perforation, and containing a distinct canal along
their attachment to the wall. Ehrenberg, too, describes
these diaphragms, which divide the internal cavity
regularly into three distinct compartments. ‘his ar-
rangement is also shewn by heat, and by acids; and the
various portions separate themselves so neatly, that we
may, in a certain manner, effect a most accurate dissection.
In this genus, these diaphragms have the characteristic
condition of very various degrees of flexature, which are
constant in each species, and impart to them the most
elegant appearances. In the deduplication, the line of
division between the new individuals, and the fine lines
which form the boundaries of the two new lateral surfaces,
precede the appearance of the corresponding diaphragms.
These are the fine lines delineated by Kiitzing within the
vittee, and regarded by him as the internal margins of
the canals, in which he believes the vittee themselves to
meet together. The deduplication of Grammatophora
greatly resembles that of Achnanthidium.

Ehrenberg describes the internal substance as consisting
of a central transparent and colourless body, containing
small gastric vesicles, and terminated at each extremity
by three-lobed dark-green appendages, which project into
the three corresponding cavities. ‘The cushions (cuscinetti)
or hinges that retain the frustules in connection are
very evident, in all the thirteen species of this genus, as
in the Zabellaria fenestrata; and this remark goes to
confirm what we have said of that species.

The family of Tabellariece (Zetracyclus, Tabellaria,
Terpsinde, and Grammulophora) constitute by themselves

.

ANIMAL NATURE OF DIATOMEA. 475

alone the order Stomaticse. The two preceding families
(Licmophoree and Striatellee) are comprised in the order
Astomaticae. These two orders constitute the tribe of
Diatomeee vittatee.

Any one examining these beings with diligence will
entirely convince himself that the distinction of the two
orders is altogether insufficient. No Tabellaria has a
central perforation in the secondary surface, at all to be
compared with that of the Diatomez, constituting the
order Stomatice in the preceding tribe. Nor have I
succeeded, moreover, in discerning the other four
perforations, described by Ehrenberg as existing in the
middle of the terminal surfaces. As to the four genera
comprised in this family, since the sole character by
which they were united together, and which was brought
to establish the principal distinction between the Fra-
gillarieze and Striatelleae, has been proved to be erroneous,
it will remain to be inquired whether there be other dis-
tinctive characters. I firmly believe that Tabellariez
and Striatelleze ought to constitute one family, since the
diaphragms, which Ehrenberg considers characteristic
of the second exclusively, are not wanting in the first.
The only doubt that I could rationally entertain would
arise in respect to the genus Zerpsinde. The figure
of the lateral surfaces, the total form of the frustules,
the arrangement of the vittae, the direction of the appa-
rent transverse canal, finally, the similarity to the other
allied genera in external aspect, would induce us to regard
the frustules as connected to the head of each other,
rather than laterally ; as we have already stated, to give
a clearer idea of the subject. But then, how can we recon-
cile the transverse deduplication with all the other instances
in which, on the contrary, it is longitudinal? For if we
would attribute a greater degree of generality to this law
than to any other ; setting out from the direction of the
deduplication, always parallel to the secondary surfaces, to
decide upon the correspondence of all the other parts
with each other, we must then withdraw the title of

476 ANIMAL NATURE OF DIATOMEE.

general from the other law (which is laid down as general),
that the direction of the vitte is always longitudinal. In
either case, the genus TZerpsinde varies entirely from its
allies, so that I think it must be regarded as the type of
a distinct family.

Owing to the mere presence of vitte, Kützing has
elevated the group of three families just examined, no less
than to a degree superior to that of an order, and which
he denominates a tribe. The analysis we have instituted
appears to me sufficient to prove that this characteristic
condition is solely due to the larger development of an
organ which really exists, or is im some degree repre-
sented, in the various families of the preceding tribe.
And though, systematically, we might wish to assign it a
great importance, yet in a natural classification it must
certainly be subordinate to the assemblage of characters.
Therefore, abstracting this character, and looking solely
to natural affinities, I believe that the Licmophorez ought
to be placed near the Gomphonemez, with the exception
that the genus Zicmophora is to be placed by the side of
Synedra, and therefore in the family of Surirellez ; and
all the other vittated Diatomeze must be ranged in the
order Fragillarieze.

58. Coscinopiscus.—Lndividua solitaria, libera, lorica
bivalvis silicea, in latere secundario disciformis, cribrata.

The only essential character that distinguishes this
genus from the Cyclotelle, is the areolation of the
secondary surfaces. And it is entirely on this account,
that, whilst belonging to the first tribe, it is placed in the
last. We ought to repeat here, that when treating of
Cyclotella, we noticed the points and radiated lines in
the lateral surfaces of the freshwater species (operculata,
Meneghiniana) and the fossil ones, (minutula, Rotula,) a
circumstance that imperiously requires an union of the
two genera. In what relates to this areolation, the expres-
sion cridrata, of Kützing, includes a false idea, inasmuch
as these cells are not perforations at all, as this author

ANIMAL NATURE OF DIATOMER. ATT

states (/orica perforata). The observation that, by placing
the object alternately nearer to, or more distant from, the
microscope, the cells and their intermediate spaces appear
successively in light and shade, is sufficient to prove that
the appearance is produced either by simple depression or
elevation, causing a difference in the surface, or perhaps
by minute cavities in the thickness of the wall itself.

Kützing takes no notice of the marginal perforations
described by Ehrenberg, who enumerates as many as
twenty-five in C. lineatus.

Ehrenberg describes the internal substance, either
collected into a globular mass in the centre, or radiating
irregularly all round from the centre towards the circum-
ference, or more frequently arranged in small distinct
globules, like those of Melosira. He sees, also (C. patina),
a globular gland, and a contractile diaphanous area which
he believes to belong to the male sex.

59. ActinocrcLus.—lndividua solitaria, libera; lorica
bivalvis silicea, disciformis (breviter cylindrica) cellulosa;
cellule radiis pluribus levibus interrupte. Septa interna
nulla.

In a specimen of chalk marl, from Oran, in my pos-
session, which consists almost entirely of Coscinodisci,
Dictyoche, Melosire, and spicule of sponges, I could
not possibly find a single Actinocyclus, although seven
out of twenty-four species of this genus are indicated in
this substance. ‘This proves only one circumstance,
which, for other reasons, can easily be imagined, that in
the same formations the species and genera appear to be
different at different points. I think, also, that I ought
to introduce two observations equally applicable to this
genus and both the preceding and subsequent genera.

Among the innumerable valves of most species of
Coscinodiscus, more or less regularly curved, many are
found to be flexuose or curved in various ways; there is
this variety of curvature in valves perfectly similar to
each other in every other character. Considering, then,

478 ANIMAL NATURE OF DIATOMER.

that in A. undulatus the six apparent rays are produced
by a similar flexuosity, a doubt necessarily arises, either
that the two genera are not sufficiently distinct, or that the
characters deduced from this flexuosity are not sufficient
to distinguish the species. There occurs, also, naturally
to the mind, a comparison under this aspect of the
Coscinodisci with Campylodisci and the flexuose Surirelle.
In some individuals exactly referable to Coscinodiscus
eccentricus, and which preserves both the valves, there
are seen five incomplete radii, which vanish entirely when
the object is withdrawn so far from the microscope that
the surface only is visible. I conclude from this that
these radii are so many internal partitions (sett). On
this supposition, the species would not belong to any one
of the three genera, Besides Ehrenberg having also
found it alive near Cuxhaven, in the North Sea, it would
seem improbable that such an organic condition could
have escaped so expert an observer ; and we must, there-
fore, suppose that a different thing is referred to.
Kiitzing describes and represents the radii to be per-
fectly smooth; Ehrenberg, again, though he does not
express it in his figures, says that they are finely punctated.
In almost all the species there are indicated marginal
apertures corresponding to the radu. In many, which
Ehrenberg observed alive, the coloured internal substance
was variously grouped into many lobes near the centre.

60. Acrınorrrenvs. —Individua solitaria libera, lorica
bivalvis silicea disciformis (breviter cylindrica), cellulosa;
cellule radus septisque internis radiantibus pluribus
inlerrupla.

The beautiful observations of Ehrenberg are fruitful in
very important particulars relative to some species of this
genus, (duodenarius, sedenarius, octodenarius.) Of these
particulars, Kützing takes no notice. The triangles into
which the disc is divided by the radii, appear alternately
clear and dark, precisely as happens in Actinocyelus
undulatus, where that appearance is evidently produced

ANIMAL NATURE OF DIATOMES. 479

by the flexuose state of the surface. A line traverses
the middle of these triangular spaces. The mar-
ginal perforations correspond to the lines which border
the triangular spaces in 4. sedenarius, to which again
they run in the middle of those of A. duodenarius
and of A. octodenarius ; and the internal septa (sed),
according to Ehrenberg, always correspond to those radii
which do not terminate in an aperture. We learn, too,
from the figures, that the areolation of the surface is con-
tinued without interruption even over the radii, and that,
besides the indicated apertures, there are visible also
those of the opposite surface, which alternate with the
former. And Ehrenberg observes, that on this account
there occurs an optical illusion not easy to explain.
Hence arises a suspicion that an equal number of septa
(setti), but alternating with each other, project from the
inner superficies of both surfaces without reaching the
opposite surface, and so the marginal apertures belong
sometimes to one, sometimes to the other.

All the species do not seem to have the same structure.
In some, at least, (lernarius, senarius, octodenarius,) the
radii are figured smooth, as in Actinocyclus; it is not
said that the triangular spaces are alternately clear and
obscure, nor that they are traversed by a longitudinal
line; and there remain doubts as to the marginal
apertures.

As to the internal organisation, little can be collected
from the observations of Ehrenberg.

Finally, it deserves attention, that the fourteen species
enumerated in this genus differ almost exclusively in
the number of radi. Two only, (senarius, hezapterus,)
having the same number, are much different from each
other. Three have unequal numbers.

The family of Coscinodisce» (Coscinodiscus, Actinocy-
clus, Actinoptychus) is, even in the opinion of Kiitzing,
more nearly allied to that of the Melosireze than to any
other. I believe that both the Campylodisci and flexuose
Surirelle are to be regarded as allied to this family.

480 ANIMAL NATURE OF DIATOMES.

61. Lirnoprsmium.—ZIndividua a latere secundario
triangula in corpus prismaticum articulatum conjuncta.

The several frustules are united together by a shorter
intermediate body, in which Ehrenberg observed a granu-
lated surface ; this, he says, appears in young individuals
only, which are, therefore, pliable when dried. He
regards this granulation as indicating the process of
siliceous ossification.

The only species of this genus (Z. undulatium) in-
habiting the North Seas, is too little known to exclude
all doubt as to its nature.

62. Ampnıtetras.— Individua a latere secundario
quadrangula (depressa) ad angula isthmo molli concatenata.
Catene breviter stipitate adnate.

Kiitzing himself observes, that the species of this
genus may easily be thought to belong to the IJsthmie.
The only difference is that upon which the distinction of
the entire family is founded, that is, the angular figure of
the lateral surfaces. This character is, indeed, extremely
conspicuous, and in want of other data may serve very
well to distinguish genera. But that this is of itself
sufficient to separate, not families merely, but even
orders, will be conceded with difficulty in a natural
classification.

I found the very beautiful A. ‘antediluviana among
some specimens of Biddulphia quinquelocularis, from
Calvados, obligingly supplied by Brebisson. 'The smooth
fascia deserves attention ; it traverses the frustule in the
direction of its length. It is sometimes absent, some-
times double, or even triple. The appearance of the
areolation is different from that of the allied genera.
It seems produced by minute projecting papille. The
ample round apertures are very evident, corresponding
with each of the four angles of the secondary surfaces, as
described by Ehrenberg, but omitted by Kiitzing from
his description as well as his figure.

ANIMAL NATURE OF DIATOMER. 481

Kützing does not acquaint us with his authority for
referring as a doubtful synonym of this species to the
Isthmia vesiculosa of Agardh, which, from that author’s
description, would rather appear to be a Desmidiea. In
my monograph of the Desmidiez (1840), I had regarded
this species as the type of a genus, which at that time
was by Kützing denominated Isthmosira.

I have not happened to meet with the 4. adriatica
recently published by Kiitzing, (Phycologia Germanica,
p- 115,) which, by the strong prominence of its angles,
is much more allied to the Isthmia.

It is to be observed, that this projection varies very.
much in the preceding species, as stated by Ehrenberg,
and as I have observed in the specimens before men-
tioned. The other species, A. parallela, which hitherto
has only been found in a fossil state, seems to be very
distinct. .

63. AmPHIPENTAS.—Individua pentagona.

Both species of this genus are of a doubtful nature.
Collecting here together all that is referable to the family
of Anguliferce, (Zithodesmium, Amphitetras, Amphipentas,)
I can only repeat what was before said of the second of
these genera. ‘The first is uncertain in its nature, but,
at all events, can have no affinity with the second. The
last has some resemblance, at least in external ap-
pearance.

The two families, Coscidonisceze and Anguliferze, con-
stitute the order Disciformes. I know not what character
can have led Kiitzing into this union, for the very name of
the second family contradicts that of the order. I believe
that the Coscinodiscee cannot be separated from the
Melosiree, and that the Anguliferee, excluding the
genus Lithodesmium, ought to be united to the Bid-
dulphieze.. :

64. Trıropiscus. — Individua singularia? libera ?
f 44 3] :

482 ANIMAL NATURE OF DIATOMER.

lorica bivalvis discoidea circularis, in utroque latere
(secundario) tribus processibus appendiculata.

The only species of this genus, which of itself consti-
tutes the family of Tripodiscee, does not essentially differ
from the Coscinodisci, except by three short appendices
projecting from each of the lateral surfaces, which are
tubular, and terminate in an aperture. Ehrenberg,
also, suspects the presence of other smaller marginal
apertures. The areolation of the surface is so confusedly
represented in the figure, as to lead to the belief that
even the organic condition is complicated, which gives
that appearance.

65. Istumia.—Individua trapezoidea vel rhombordea,
compressa, cellulosa, zona transversali ex cellulis minoribus
Sormata, notata, stipitata, isthmis majoribus in catenas
subramosas irregulares conjuncta. Divisio oblique trans-
versa.

The complicated synonymy of the two species of this
genus (enervis, nervosa) justifies the new name given by
Kiitzing to the second. The Conferva obliquata of Smith
belongs to the first, and therefore Ehrenberg was in
error when he bestowed upon it a new specific name
(enervis). ‘The other required to be named, and Kützing
was fully entitled to call it Z. nervosa. By the laws of
synonymy, therefore, the two names odliquata and
nervosa ought to remain. The longitudinal costz of this
latter are quite extraneous to the surface; they project
slightly into the interior cavity. Both im the one and
the other the siliceous cellular membrane of the median
portion persists, whilst within it a formation of two
lateral valves takes place, which complete the two indi-
viduals preceding from the deduplication. This process
reminds us of that of the Achnanthex, and approaches
the reduplication of Desmidiez.

The transverse zone, represented by Kützing in the me-
dian portion, is neither constant nor regular. I believe it
to be produced by the permanence of some portion of the

ANIMAL NATURE OF DIATOMER. 483:

cellular siliceous external membrane, which is lacerated in
the deduplication. A portion of it may remain in the
middle, whilst its lateral extremities are denuded, or vice
versd, the former may remain denuded, and the latter
covered. It still remains to be explained how the
formation of the new valves takes place, whether they are
organised 7 situ, or project by degrees from the companion
valves, to which they are contiguous from the beginning,
the intermediate ring only developing itself subse-
quently (consequentemente), as in Melosira.

The gelatinous isthmus, which connects the individuals
together, and the stipes by which the entire chain
is affixed, seem to prove the presence of an exterior
gelatinous membrane.

66. ODoNTELLA.— Individua levia, compresso tere-
tiuscula medio fasciata utroque apice cornibus binis late-
ralibus instructa et concatenata, adnata.

I am compelled, by the want of specimens, to confine
my examination to that one only of the five species of
this genus which I have already treated upon in refer-
ence to my Pleurosira thermalis ; and I can only insist
upon what I have stated on that occasion. ‘The indi-
viduals of Odontella polymorpha, have an elliptic cavity
in the middle, and at the extremities are compressed in
the direction of the greater diameter of that ellipse; but
viewed laterally, they present an obtuse, but linear edge
(canto). 'The lateral processes, by which the individuals
are connected together, are very evident. The difference,
therefore, between this form and that of Pleurosira
thermalis, and of P. Baileyi, is very great. Another
important difference exists in the conjunction of the
median ring with the two lateral valves. In my Pleu-
rosira there is on both sides a large, distinct, circular
canal (canaletto), evidently projecting into the inner
cavity, and corresponding to an external furrow. But in
the Odontelle there exists neither furrow nor projection ;
and I really doubt whether there be a fine canal. A

484 ANIMAL NATURE OF DIATOMER.

like condition exists in both with respect to the delicate
points on the shield, which Kützing says he has omitted
in his figure of Odontella ; these being absolutely re-
ferable to the internal substance, as in the Melosire.

67. BrppuLpH1a.—lndividua concatenata, punctato-
cellulosa (cellulis in lineas rectas transversales ordinatis),
utroque latere obtuse dentata (dentibus marginalibus majo-
ribus) septis transversalibus internis loculosa.

The inner cavity is not divided into distinct transverse
cells, because the septa, far from being complete, only
project in a very little way. Their greatest prominence
corresponds with the extremities of the frustule, and
thence they proceed, growing more slender, towards the
margins of the lateral valves, to which they exclusively
belong. A similar elevated rim (orlo) in the internal
cavity limits, also, the lateral processes by which the
frustules are connected together. Each of these processes
terminates in an acute corner (spigolo), and has there-
fore a three-sided figure, and is situated obliquely.

The terminal surfaces (lateral in respect to the chain)
are smooth, or they present an elliptico-elongate figure,
traversed, parallel to the smaller axis, by two lines which
mark the conjunction of the two lateral valves with the
median body. Corresponding externally to these lines,
is a deep furrow, which is clearly seen in the projecting
corners (spigoli); internally there is a projecting fold
(cercine), like an incomplete diaphragm of the areolar
border. Hence the form of the frustules is very different
from that indicated by Kiitzing, who represents them as
flattened cylindroids. For they are almost parallelo-
pipeds, and when they are united together by an external
siliceous cellular membrane, more or less incompletely
persistent, they constitute a prismatico-quadrangular
filament. When they are free, the extremities are
thinned, rounded, and lobed, according to the number of
incomplete cells. ‘The two primary surfaces are smooth ;
they present transverse elevations and depressions in

ANIMAL NATURE OF DIATOMEM. 485

correspondence with the cells above mentioned. The
lateral processes are more or less completely denuded of
the fine cellular membrane, and are united in con-
catenation with each other by a cushion (cuscinetto),
bounded externally by a precise line, but internally
irregular.

The deduplication takes place in this genus as in those
preceding. The double ligament merits observation,
which remains to unite the median lobe of both surfaces
of each extremity with the corresponding (ligament) of the
adjoining frustule. ‘This ligament, from the gradual elon-
gation, breaks across in the middle, maintaining its rigidity.

In the Adriatic we have the two species, guinquelocu-
laris and trilocularis. To the second I refer a form with
smaller and less elongated frustules, which at first I
thought a new species, and as such communicated it to
Kützing, who, on the other hand, believed that it belonged
to the guinquelocularis. I note this circumstance to in-
dicate an important organic condition. When the frus-
tules are empty and diaphanous, we can easily see,
owing to the transparency, the coste of the surface
opposite to the one observed, and especially the two
extreme ones, which correspond to the least thickness,
and can therefore be seen along with those of the anterior
surface. The number of the so-called cells is then appa-
rently increased by two. It happens in this way that
the guinguelocularis sometimes resembles the septem-
locularis.

Kützing ascribes to this genus, as a doubtful species,
the Denticella Fragillaria, of Ehrenberg.

In the guinguelocularis, I once saw a frustule broken
in the direction of the conjunction of the lateral valves
with a median cincture, and surrounded by 4—6 poly-
hedral corpuscules, of a diameter equal to one fourth
that of the frustule, and of a cellular structure, adhering
to the margin of the fracture. j

Finally, we cannot but remember the Isthmia ner-
vosa, which seems to differ from Biddulphia in no

486 ANIMAL NATURE OF DIATOMES.

other respect than the trapezoidal figure of its primary
surfaces.

68. Zycocreros. — Individua libera (?) compressa
utringue corniculis doubus perforatis instructa, non con-
catenata.

The two species of this genus, (Z. Surirella, Z. Rhombus)
were observed in a living state by Ehrenberg, who saw
that they were always free, and thence established,
principally on the want of stipes and of cateniform con-
junction, their generic distinction from Biddulphia.

He observed, also, the smooth median fascia which he
compared to that of the A/elosire. Having regard to the
rhomboidal figure of the section, and the large terminal
perforations of the two lateral processes, the compari-
son with the genus Amphitetras is much closer.

In the chalk marl of Oran, I saw a fragment which I
could not better refer to any other genus of Diatomez.
It was an oblong body, with three lobes on each side,
and two lobes with a large circular perforation at the
two extremities. The space corresponding to the two
median and more prominent lobes, was divided from the
two others by means of two very distinct lines, and the
‘whole surface was regularly areolated.

The family of Biddulphize (Is/hmia, Odontella, Biddul-
phia, Zygoceros,) has affinity, according to Kiitzing, with
none but the following one (Angulatz) ; and in the letter
before referred to, he intimated to me his thoughts of
reuniting them to the Tripodisciee. Here I remind the
reader of what I have said on the genus Amphitetras, and
of the family of Angulifer, which, perhaps, excluding the
genus Lithodesmium, seems strictly to connect itself with
the Biddulphiee. If there really exist also an affinity
with the Tripodiscez, as Kützing maintains, that affinity
may suggest the transition to the Coscinodiscee and
thence to the Melosirez.

In respect to the internal organisation of the Biddul-
phiez, we learn, from the fine observations of Ehrenberg,

ANIMAL NATURE OF DIATOMER. 487

that there is always a coloured substance disposed in
lobes, which he supposes to represent the ovaries, in the
midst of a transparent and colourless body.

69. Triceratium.—Individua libera, lorica bivalvis
triangula, in utroque latere tridentata vel corniculata, non
concatenata.

The perfect resemblance of the primary surfaces, and
the large apertures of the three processes in the secondary,
render this genus precisely intermediate between Amphi-
tetras and Zygoceros; nor, indeed, can I comprehend
how Kiitzing could place them in three separate families,
and even in two distinct orders. As to the minute
apertures, which Ehrenberg states to be uncertain, in the
conjunction of the lateral valves with the median fascia,
we may suppose that they are only apparent as in the
Biddulphie, where they certainly do not exist. Of the
four species hitherto described, two (Favus, striolatum)
were observed by Ehrenberg and by Sonder in a living
state, in the North Sea.

Like Zygoceros, the Triceratia become detached com-
pletely in deduplication, and, therefore, do not, like
Amphitetras, form cateniform chains. They possess, also, a
more decided motion. This character, however, does not
appear to me of so much importance as of itself to fix
the limits of distinct families; and Kützing himself,
who proposes a separate family (Angulate) for the
genus Triceratium, comprises Zygoceros in that of
Biddulphiee, where the catenzeform association is so
preponderant.

70. Acrınıscvs. —Individua solida radiata, stellam
amulantia.

Although, besides a species exclusively fossil (4. Stella),
omitted by Kützing, one of the other two has been
observed alive by Ehrenberg (4. Pentasterias), and the
other exclusively in this state, (4. Sirius,) still we

488 ‚ANIMAL NATURE OF DIATOMER.

have no positive data as to the internal organisation of
the genus.

71. Musocena.—ZIndividua libera solitaria, annulum
circularem aut angulosum sepe spinescentem referentia.

On the five species of this genus we can only repeat
what has been said of Actiniscus.

72. Dictrocna.—Individua reticulata spinosa, libera,
solitaria.

Independently of the distinctive characters of the ten
species (one, the D. gracilis, being added by Kützing)
which merit attention by the variety of form, size, pro-
portion, disposition, and even number (D. aculeata, D. tri-
Senestrata) of the (maglie) cavities, as well as the presence
and length of the spines, already noticed by Ehrenberg,
this author’s observations on some of these species that
may be studied in a livingstate (aculeata, Speculum, Fibula)
are very valuable. From these it appears that the animal
is soft, and quite external to the siliceous body which it
bears on the surface, like a dorsal shield (scudo), as the
Arcell@ bear their calcareous shell.

Though observations are wanting to show that the
organisation proved only in some species of this last
genus (Dictyocha), is common to the whole family of
Actinisceze, yet we may infer by analogy that it is so.
In fact, we cannot interpret the structure of those beings
in any other way than by supposing the body of the
animal to be external.

And how slight soever, may be our knowledge of the
Dictyocha, it is still more than sufficient to prove an
organic type not merely quite different from that of the
other familiescomprised in the same order (Appendiculatz),
and in the same tribe (Areolate), but even from the
type of all the other Diatomez.

I believe that whatever be the rank assigned to the
group of Diatomez in the Zoological series, the first

ANIMAL NATURE OF DIATOMER. 489

division ought to be that of true Diatomez and Actiniscee.
Yet, in the actual state of science, we may characterise
the first as completely loricated, the second reduced, in
the dermal skeleton (dermoscheletio), to the presence of
a simple dorsal shield. It is indeed true, that, in other
classes of animals (Mollusca), the characters derived solely
from the dermal skeleton have not so high a taxonomic
value. It is possible that we may come to establish
the basis of classification, even in Diatomex, upon the
particulars of their intimate organic structure ; but since
this may never be realised, I believe that, provisionally
at least, this character should be considered the prin-
cipal one.

The order, therefore, of Appendiculate (Tripodisciese
Biddulphiez, Angulate, Actiniscez) is the most artifi-
cial of all, and even in that respect inconsistent. By the
same title that Zygoceros and Triceratium are inserted,
we ought also to insert Amphitetras and Amphipentas
(if they be true Diatomez). The Biddulphiez constitute
a very natural group, when we unite the Anguliferse
and exclude Zithodesmium and the Angulate. There
would remain some doubt as to the genus Odontella,
in respect to the want of areolation in the shield. Zri-
podiscus would remain intermediate between this group,
and the Coscinodiscex. Finally, the Actiniscee, in my
opinion, ought to be entirely excluded.

Thus the entire tribe of Areolata (Disciformes, Appen-
diculata,) would be reduced to three groups only,
(Coscinodisceze, Tripodisceze, Biddulphiez,) to which,
this denomination really belongs. And here, we cannot
but adduce some considerations on the organic condition
that gives origin to it. In the Biddulphiez, the struc-
ture of the shield seems evidently cellular. In the Cos-
cinodiscex we have supposed it to be such on account of
the optical: phenomena it presents, and examination
confirms this supposition. Comparing, then, the tribe of
Areolatze with the preceding, under this point of view,
and independently of the animal or vegetable nature

490 ANIMAL NATURE OF DIATOMER.

of Diatomez, considered as organised beings, we find
ourselves of necessity, reduced toa dilemma. Either the
shield of the Areolate has a structure entirely different
from that of the other Diatomez, or the shield of the
latter has a compound structure, which escapes the eye,
though armed with the highest magnifying powers,
owing to the tenuity, and minuteness of its elementary
parts. Perhaps some one may attempt to elude the
question, by admitting that this shield can be no other
than a product of secretion. But, besides that, the
products of secretion are living beings, organised and
susceptible of their own ulterior organic modifications,
as we have previously demonstrated : in either mode it is
necessary to admit a particular organisation in the se-
creting organ, because its products assume a particular
configuration and texture. If, therefore, the vital and
organic power be understood as limited solely to the soft
substance, and extended afterwards to the solid, it always
comes to be the same thing—the peculiarity of organisa-
tion. The difference is reduced to the soft or solid
constitution ; nor does this isolated condition prove, in
my opinion, the mineral condition of a tissue which does
not present any character either of crystallization or
inorganic deposition.

Of the two discordant opinions, I believe we ought
to admit that which supposes by analogy the usual
elementary structure to prevail in the shields of all
Diatomez. And, in truth, the presence of strie, points,
depressions, elevations, manifests, in many even of those
not areolated, a structure neither uniform nor continuous.
We find, too, that independently of this condition, many
degrees of correlation connect the genera of the last tribe
to some of those of the two preceding. The Odontelle
are rightly placed near the Biddulphie and Isthmie,
though they do not possess an areolated shield. And if
a decided organic affinity be undeniable in the entire
organisation of such beings, it is reasonable to suppose,
that even in the structure of an organ common to them

ANIMAL NATURE OF DIATOMER. 491

all, the differences may be produced only by a slight
modification in form, and principally in the dimensions,
of the organic elements.

It remains to be decided what this structure is. The
shield of the Biddulphiee seems to be a very simple
cellular tissue. It is true, sufficient observations on its
origin, formation, and successive growth, are wanting ;
but although we have no direct observations (which
may deceive), we ought necessarily to admit it to
be such. It will then be the same as that of other
Diatomez, which often appears to be a very simple,
uniform, and continuous vitreous lamina, but this appear-
ance, perhaps, arises from the minuteness of the cells of
which it is constituted, or from their complete obstruction
and perfect continuity.

Whatever be the structure of the Areolate, it can
never be regarded as belonging to the walls of a cell.
Indeed, on the supposition of the vegetable nature, and of
the inferior rank that the Diatomese would occupy in
the class Alg®, we must assert for these, as for all the
others, the same condition of a simple cell. For in a
system where the distinction of monogonimic, poly-
gonimic, and ccelogonimic cells is adduced as of high
taxonomic value, a character of so much higher import-
ance cannot be lightly neglected.

The study of microscopic beings presents much greater
difficulties than that of the microscopic parts of larger
organisms. The ideas that we habitually form to our-
selves of the great and the small, are relative to the
capacity of our senses, and he who sharpens those senses
the most by the aid of physical instruments, most extends
the relations of those ideas, to distant confines. In this
way we come to persuade ourselves, that in nature there
exists no absolutely great nor absolutely small. The
minutest organisms are not, therefore, the most sim-
ple in construction, and their organisation frequently
baffles all means of observation. It follows, from these
reflections, that in the study of beings of a given family

492 ANIMAL NATURE OF DIATOMER.

or class, it assists us greatly if we select those that
present the greatest complication of structure, because
the comparison of these may reveal the organisation
which others disguise under an assumed simplicity.

In the three tribes we have examined (Striate, Vittate,
Areolate), Kützing arranges all the Diatomeze which he
believes to form a section of the first of the two classes
into which he divides all the Alge. No one who con-
siders that even the Char are comprised in the same
class, will feel any wonder at this assemblage. But
without calculating either the degree or the position
attributed to the group of Diatomez in the Organic
Kingdom, and attending only to the examination of their
ulterior division, I believe that the observations adduced
may serve to demonstrate that in the three proposed
tribes we have unnatural dismemberments and asso-
ciations. The same conclusion prevails also in respect
to the six orders (Striatze, astomatice and stomatice ;
Vittatee, astomatice and stomatice ; Areolat&, disciformes
and appendiculatz,) as well as to the ulterior divisions in
the first two, taken from the continuity or interruption
of the striz and the presence of one or two stomatic
apertures. Much more naturally established do we find
the nineteen families, (Eunotiese, Meridiez, Fragillaries,
Melosirex, Surirellee, Cocconoidee, Achnanthee, Cym-
bellese, Gomphonemez, Naviculeze, Licmophores, Stria-
telleze, Tabellariee, Cosconidiscex, Angulifere, Tripo-
discez, Biddulphiee, Angulatze, Actiniscez ;) respecting
these we have seen that, in the actual state of science, few
changes would be fully justified. Such changes appear
to me to be the following :—the union of Meridiee with
Fragillariee ; the separation of the genus Licmophora
from the family that bears its name, to join it with
Bacillarie and Synedre in the family of Surirellex ;
to examine it again comparatively with that of Navi-
culez, to decide upon the presence, constancy, and value
of the character of a median aperture, which alone serves
to separate them; the comparison, under this point of

ANIMAL NATURE OF DIATOMER. 493

view, of the Licmophorez (excluding the genus Zicmo-
phora) with the Gomphonemez; the necessary fusion
into one only, of the two families Striatellee and Tabel-
lariee, the character of median aperture given as dis-
tinctive of the second being absolutely false, with the
separation of the genus Zerpsinde as a distinct type; the
removal of the Coscinodiscez, and probably of the
Tripodisceze, among the Melosirez; the grouping together
of the three families, Angulifere, Biddulphiee, and
Angulate, excluding Zithodesmium as uncertain; and
leaving there the genus Odontella, which demonstrates
the affinity of the entire group with the Melosiree ;
finally, the decided separation of the Actinisceze from all
the other Diatomez.

These changes being admitted, and the principle being
conceded, to its full extent, not to allow absolute value to
any character taken separately, the Diatomez would be
divided into two sections; the Actiniscex, and all others
that could be comprised under the name /oricate, unless
we should refuse to acknowledge that the first (section)
have really any bond of alliance with the second, except
the siliceous nature of the dermo-skeleton. In the
loricate it would be hasty to separate the genus Zerpsinde
from all the others, which might be reduced to eight
families only :—1, Eunotiee; 2, Fragillariez, (uniting
with them the Meridiez, the Striatelleae, and the Tabel-
larieze ;) 3, Melosirex, (comprising the Coscinodiscee,
Tripodiscee, Anguliferee, Biddulphiee, and Angulatze ;)
4, Cocconoidee; 5, Achnanthex; 6, Cymbellee; 7,
Naviculez (with all the Surirellez ;) 8, Gomphonemez
(with all the Licmophoreze, except the genus Licmophora.)
These families, too, might be separated into two groups,
according as the temnogenesis takes place by simple
deduplication, (Kunotiex, Fragillariee, Naviculee, Gom-
phonemez, Cymbellex, and Cocconoidex,) or by redu-
plication, (Melosiree, Achnanthee.) I do not believe,
however, that this distinction is so essential as it may.
seem ; for even in this case it appears to me that the

494 ANIMAL NATURE OF DIATOMEE.

evident complication of the process in the second group,
proves the like of the apparently simple process of the
first. In fact, it is indeed always necessary that the two
new lateral valves of the two individuals be organised,
even in simple Naviculez, and the separation of the two
pre-existing always precedes the deduplication. It does
not, therefore, appear to me that we can entirely agree
with Ehrenberg in what he adduces to distinguish the
process of deduplication (sdoppiamento) from regeneration
and reproduction. We cannot say that anything gives
way, where the formation of new valves appears, and
that the division is effectuated by that. The division
is merely the last stage of the process, and the per-
sistence of the two exterior valves does not seem to me
sufficient to prove that a total regeneration of the two
new individuals has not occurred. Nor can any one
prove that a reabsorption of organic substance and a
local renewal (ripristinamento) of organisation has not
taken place. And since the new parts which make their
appearance change the individual essentially, and do not
belong at all to its individual growth, as Ehrenberg
sagaciously observes, from this it clearly follows that it
had previously ceased to enjoy individual life. If I were
not afraid of appearing too transcendental, I would com-
pare the progressive deduplication (sdoppiamento) in the
Diatomez, with the successive development of the
terminal bud (gemma) of the Sertulariee. This unfolds
itself (si sdoppia) into two organisms, which, in smaller
dimensions, might appear almost equal; but one of these
enjoys an individual life, the other, again, becomes halved
(st sdoppia), and so on indefinitely.

As respects the rank and position to be allowed the
Diatomez in zoological classification, it results from the
observations hitherto collected, that nothing positive can
be asserted. No one, henceforth, will have a right to
contradict the authoritative opinion of Ehrenberg, who
ascribes them to the class of Polygastric Infusoria.

ANIMAL NATURE OF DIATOMEA. 495

[Kützing has recently published (‘ Botanische Zeitung,’
3d of April, 1846, No. 14, p. 249) some new Diatomez,
discovered by Brebisson, at Falaise. An Achnanthidium,
a Gomphonema, two Navicule, a Ceratoneis, two Synedre,
and a new genus belonging to the family Striatellex.

73. PLEURODESMIUM.— “Trichoma articulatum fascie-
Forme, articuli plani sepe geminati, fascia transversal
media hyalina notati, ex sulcis longitudinalibus obsolete
punctatis (perforatis ?) costati ; costis rugulosis.

And thus is completed the number of seventy-two genera
proposed (in the preceding enumeration Kützing omitted
number 49 by mistake); and the number of species is
brought up to more than eight hundred. |

(For further information in regard to these genera, and’
additional ones since proposed by Kützing, see his
‘Species Algarum,’ 1849.—Ep.)

ANNOTATIONS.

Page 4.—Without engaging in controversy, rather to
show our high esteem for Kiitzing, we deem it necessary
to subjoin a few words, lest we should seem desirous of
eluding the question, or not duly weighing the reasons of
this excellent author. “ There do not exist in nature
definite (scharfe) boundaries between species, classes, and
kingdoms, and our having admitted these theoretically,
leads us to regard some inferior animal forms as plants,
and some vegetable forms as animals. ‘The limiting of
the boundaries between the two organic kingdoms is
always a problem. All metaphysics should be excluded
from the study of nature, in which we can only proceed
by the empirical way, and therefore we ought to restrict
ourselves to what we see, observe, and understand.”
These thoughts, expressed by Kützing, (‘ Ueber die
Verwandlung der Infusorien in niedere Algenformen?
Preface,) are strictly logical. But the conclusion deduced
by the author is not legitimate, that we ought to admit a
common point of departure for the two kingdoms. If it
be absurd to admit the problem to be solved positively, it
is equally so to admit that it is decided negatively. The
contradictions to which he alludes, as produced by the
false supposition of the existence of a limit between the
two kingdoms, belong to authors or books, and not to the
science. The very examples, the vibratile cilig of Surirella
Gemma (Ehrenberg), and of the spores of Vaucheria
clavata (Unger), have an answer in the observation of
Siebold. All the observations on the mobility of the
sporidia of the inferior Algz, of the spores of Vaucheria,

ANIMAL NATURE OF DIATOMEE. 497

of the Zoosperms, of Sphagna, Chare, Marchantiee,
Filices, and, lastly, of Fucacez, prove nothing more than
this, that vegetable beings, in certain stages of their
development, and in certain conditions, possess a mobility
that simulates animal mobility. It is a positive fact,
that the complicated animal organisation discovered by
Ehrenberg in many of his polygastric Infusoria, cannot
be recognised in some that are referred by analogy to the
same class; but it does not at all follow, from this, that
we ought to regard these sporidia and the spores of
Algze as animals ; for, besides their want of this organisa-
tion, they manifest an evidently vegetable nature by their
subsequent development. Neither ought we to deny an
animal nature to other beings in which this complicated
organisation exists. The multiplication by division, or,
in other words, temnogenesis, is not, as Ehrenberg
believed, exclusively animal. By good right we admit it
in vegetables also. But is the organic process by which
it is accomplished the same in the two kingdoms? If
the character, in its generality, cannot serve for the dis-
tinction, it only follows that there is a necessity for further
researches in order to discover the peculiarities.

The Closteria, and Desmidiez, in general are plants,
and not animals. In the actual state of science, we are
compelled to admit this proposition. The organic struc-
ture, the physiological phenomena, the history of their
development, the chemical materials they contain, manifest,
in these beings, a perfect correspondence with others,
which, in every point of view, correspond with the ab-
stract idea of aplant. But what they present in common
with other beings, evidently animal, is merely an appear-
ance, or, at the most, a resemblance, in external form.
Ehrenberg was misled by this appearance, and guided
by this fallacious similitude, thought that he discovered
in the Desmidiez, the same organic peculiarities which
proved the animality of other beings. Ought he to have
reasoned thus? However, the most accurate observer, and

the man of genius, is liable to error. Nor by this can
32

498 ANIMAL NATURE OF DIATOMEE.

his merit ever be impaired, or the benefits he has conferred
on science be diminished. The loss will accrue only to
those who, disdaining the fatigue of observation, content
themselves with the authority of a master, and accept
indifferently his real discoveries and his errors. Heaven
be praised, the day of authority has passed away, and he
who bends to the yoke, may wander in peace, but science
will not proceed the less, and may even derive advantage
from these errors. From the study of the Desmidiez,
and comparing them with animals, valuable knowledge
on the intimate structure of vegetables has been derived.

The very beautiful observations of Flotow, upon what
he terms Hematococcus pluvialis, seem to prove its
animal nature. Nor does the appearance of some. Alga
(determined by Kützing from the figures as Ulothria tener-
rima, U.tenuissima, Gloiodictyon viride, &e.) in the vessel
where the supposed Zematococeus had remained im-
mersed in water for some time, after having been pre-
viously dried for fourteen months, certainly demonstrate
that these represent a different stage im the existence of
the same being. If such were the case, we must infer
from it, that in despite of all appearances of animal nature,
this Zematococcus was really nothing but the germs of
some Algee, and therefore vegetable.*

We are led precisely to this conclusion by the still
more accurate and valuable observations of Kützing, on
the metamorphoses of Microglena monadina into Ulothria
zonata, and of Chlamidomonas Pulvisculus into Stygeoclo-
nium stellare. Some may raise a doubt whether the
globules, from which the filaments of Styyeoclonium are
developed, were precisely the same as those that moved
at first, and were furnished with a red spot and a
ciliary appendage; and again, whether they were pre-
viously mixed together, and confounded with the others,
owing to their resemblance in external aspect, or only
made their appearance (comparsı) subsequently. But

* See the following paper in this volume. Also on Chlamidococcus and
Chlamidomonas in ‘ Braun on Rejuvenescence.’—Ep.

ANIMAL NATURE OF DIATOMER. 499

still, admitting that we are treating absolutely of the
being that is regarded as an animal by the author,
and denominated Chlamidomonas, and that the Stygeoclo-
nium actually derives its origin from it, the conclusions
from this fact may be reduced to the following; that the
germs of Stygeoclonium possess motions similar to
animals ; that they are provided with a red spot similar
to the eyes of Infusoria; that they even sometimes possess
a terminal cilia; sometimes a transparent space or an
aperture by which they fix themselves, to vegetate; and
the supposed Chlamidomonas Pulvisculus is nothing more
than the germ of Stygeoclonium. As to the other or-
ganisms, as well animal as vegetable (Ze¢raspora, Pal-
mella botryoides, Protococcus, Gyges, Pandorina, Monas,
Gloeocapsa, &c) which seem to have an origin similar to
that of Chlamidomonas, Kützing merely intimates their
similarity of form.

Our author rightly distinguishes the two methods
pursued in the study of organic beings ; to consider them
either with Linnzus, completely developed, or with
Goethe, in their successive development. ‘The definitions
of the former are derived from an empirical synthesis ;
I do not allow that such can only be arbitrary, because
no empirical idea can be defined; for it appears to me
that we can know nothing more than we learn by our
senses, and therefore I rather believe all those definitions
to be arbitrary which are not logically empirical. The
history of the successive development of a being, ap-
proaches more nearly to the true idea that we ought to
form of it, not because that idea is absolute, for there
can be nothing in nature absolute to us who form
part of nature herself, but because the notion or con-
ception of a thing is so much the less incomplete,
the more numerous the points of view are from which
we consider it. And thus, in examining the successive
stages of development, we always fall into arbitrary
error, for time has no interruption, and in this respect
there is an imperfection inherent in our nature ; for we

500 ANIMAL NATURE OF DIATOMRE.

want a measure for the fraction into which time, as well
as space, is naturally divided.

It is true that, in the study of nature, we ought to
proceed independently and abstractedly of any precon-
ceived idea, attending to phenomena only; but still it is
necessary to select these phenomena one from another,
to compare them, to separate those they possess in com-
mon, and those in which they differ, thus gradually
ascending to synthesis. Every metaphysical idea, as-
sumed a priori as the basis of a doctrine, is of necessity
arbitrary. But synthesis, logically executed and preceded
by the analysis of individual facts, leads us securely to
the attainment of knowledge. There may be error in the
observation, or in the deduction, but never in the method.

When Kützing, combating the principle of the exis-
tence of a precise limit between the animal and the plant,
concludes that there exists no such limit, he only substi-
tutes one metaphysical principle for another, and therefore
wanders from the maxims laid down by himself just
before.

When he demonstrates that movements, and the
organs by which these are performed, are not exclusively
those of animals, and that there may be an appearance
of an eye, a stomach, and a mouth, in vegetables, he
controverts his own theory of a double nature, animal and
- vegetable, in the same being.

The observed facts are valuable. They prove the
insufficiency of the characteristics given by authors to
distinguish animals from plants. And, even if it should
remain impossible for our most remote posterity to
decide, whether given beings can, or ought to be included
in the abstract idea of a plant, or in that of animal, this
will not suffice to confound the two ideas, because their
empirical nature is relative, indeed, but not arbitrary.

Perhaps the most important observation of Kiitzing,
on this subject, is that of the different vital phenomena
presented by the most simple vegetables, according to
the prevalence in them of the external gelatinous (cellulose)

ANIMAL NATURE OF DIATOMEA. 501

membrane, or of that internal one which he terms amyla-
ceous, and which is the primordial utricle (of azotised
quaternary substance) of Mohl. In this second case,
there are movements, and cilie by which they are effec-
ted. he sporidia of the lower Algz, the spores of the
Vaucherie, the spirilla of antheridia, the filaments of
Oscillariez, are either destitute of a gelatinous sheath, or
it is softened and almost dissolved. ‘The air promotes
the development of the gelatinous substance, light and
heat that of the amylaceous.

Inseparable from the preceding question is that of
speciological and generic limitations. It is a demon-
strated and very important fact, that many organisms
described as species and genera of the inferior Alge, are
merely transitory forms of more complicated beings. The
consequence to be logically deduced, is the exclusion of
these supposed species and genera from the catalogue of
beings. He who desires to continue the enumeration of
them as such, ought, to be consistent with himself, to
establish species and genera even of the transitory forms
of all other beings in nature, unless he maintain that
the transitory forms of inferior organisms differ in this
respect from those of the superior, inasmuch as they
can persist as such, live, and multiply. I believe that
this position cannot be impugned even as respects the
most elevated organisms, since ‘Teratology furnishes a
sufficient number of examples to prove the possible
permanence of every transitory form; and in the inferior
organisms, multiplication is confounded with simple
increase. It would remain to be decided whether we
could always clearly distinguish reproduction from mul-
tiplication, and if so, whether we possess positive data
to determine the attainable point of organic perfection
of which every being is capable. But, since we are
oftentimes destitute of this secure criterion, we ought to
obtain data by observation, and to consider that develop-
ment to be the highest which is the highest we are
able to observe. Nor can any one assert that if develop-

502 ANIMAL NATURE OF DIATOMER.

ment be arrested at some intermediate form, this has
not occurred from the want of favorable circumstances,
and ought not to be considered transitory. As Mon-
strosities are classified, to facilitate study, or lead to the
attainment of general notions (concetti), so I allow that
the transitory forms of the inferior organisms should be
classified, compared and, if you please, named systemati-
cally ; but that they ought to figure in the same rank
with forms permanently attained, and truly specific, I
can never logically allow.

Page 7.—Some regard the epidermis as a product of
secretion, and therefore destitute of organisation and
life. Recent inquiries as to secretions, prove that they
are accomplished by a process exactly similar to that of
nutrition and growth. ‘The question is now reduced to
decide whether the product of epidermal secretion ceases
to live whilst it still forms part of the animal structure,
and when this change takes place. I am glad it is in my
power here to introduce a note I have received from the
learned Moses Benvenisto.

“ The epidermis, as well as the more complicated parts,
which derive their formation from it, and possess charac-
ters and functions in common with it, is certainly orga-
nised. But this organisation is of an inferior grade to
that of many other tissues, because it is simply cellular
and not vascular or fibrous. It is similar to the products
of secretion which abound in nucleate cellules, not elon-
gated into fibres, nor developed in canals; but with the
difference, derived in part from the contact of air, in
part from the action of absorbent vessels, that this external
secretion possesses no elementary liquid to maintain the
cells disaggregated, floating, and inflated ; hence result
only cells thatare closely united, compressed, and disposed
in numerous superimposed layers. But I hold a middle
course between those who say that the epidermic *sub-
stance is inorganic and dead, and those who will have it
to be existing per se, and living by a life of its own.
In my opinion it has an organisation, and therefore a life,

ANIMAL NATURE OF DIATOMEM. 503

but of a low degree, and is also the product of secretion
from another more noble and complex element of the body
over which it is extended. What is this generating ele-
ment? This is a necessary inquiry, and not less impor-
tant than interesting to the physiologist and medical prac-
titioner. This element certainly forms part of the tegu-
mentary membrane, in which the epidermis constitutes
the ultimate layer and most superficial covering. I do not
believe that it can be the follicles or crypta, because these
minute organs afford mucus, oil, or cerumen, a liquid
adapted to lubricate, but not to organise, capable of
accumulation, but not of concretion; for when once
covered with epidermis, we cannot conceive how their
apertures can still secrete oil (sego) or any other liquid
whatever; so that if the cutis be considered as the same
with the mucous follicles, the epidermis is thin where these
are abundant, and, again, it presents the greatest thickness
where these are rare, or absent, as in the palm of the
hand, or the sole of the foot; finally, because very often
in morbid thickening of the epidermis, we do not find
the follicles varying from their natural condition. But I
believe that the organs producing the epidermis, at least
in most places, and in most instances, are the papillz
which possess so many vessels of every kind, that we
cannot suppose them wanting in the function of se-
cretion. And indeed we observe that wherever the
papillae are most numerous, most developed, and most
vascular, there the epidermis is the most manifest. It
is thickest on the palms of the hands and the soles of
the feet, where, to serve the office of touch, the papille
are most numerous, and are organised and arranged in a
particular manner. It is thickest on the tongue, where
the sense of taste requires an abundance and prominence,
of the papillary organs. And speaking of mucous mem-
branes, wherever they exist there also exist sensitive
papilla, animated by nerves of sense, that is in the
vicinity of the natural orifices of the body. According
to the most recent teachers of pathological anatomy, and

504 ANIMAL NATURE OF DIATOMES.

especially Professor Rokitansky, hypertrophy of the
papille is detected beneath the condensed epidermis, in
inveterate ichthyosis, and in common warts. All accu-
mulations of epidermis which assume the form of scales,
spring from papilla developed in the form of cylinders,
villi, and rami. According to Cruveilhier, accidental
horn is a morbid product of papille of the skin, crowded
together, and twisted into a papillary substance. But
with regard to hairs growing physiologically and patho-
logically, as well as to horn, which seems always to be
formed by an agglutination of the skin, we must remem-
ber that, as they are composed of two different elements,
one an external envelope of epidermic nature, and the
other, an oily medulla, varying in colour, so both the
papilla and the follicles concur in their formation. Both
the one and the other are altered in different ways,
precisely according to their accidental, or pathological
production.”

As to the organisation of bone, there still remains a
doubt with respect to the presence of saline particles
mineralogically deposited in the parietes of the bone-cor-
puscles ; yet it is proved, that in the numerous concentric
laminee that constitute the walls of bone canals, in the
radiating tubes that traverse them, and in the bone-cor-
puscles themselves, the calcareous substance is in the same
condition as the proteine, with which it is found intimately
united.

Recent observations have proved, what might reason-
ably be supposed, as to the shells of Mollusca, that they
have a decidedly cellular structure, the lime, together with
proteine, constituting the walls of the cells.

We know that the same is true of the silex in the
epidermis of Graminex and Equisetacex, and of the
lime in Corallines and other marine Alge.

Page 8.—‘‘ A cosmical history of the universe, resting
upon facts as its basis, has, from the nature and limita-
tions of its sphere, necessarily no connection with the
obscure domain embraced by a history of organisms, if

ANIMAL NATURE OF DIATOMES. 505

we understand the word history in its broadest sense.
It must, however, be remembered, that the inorganic
crust of the earth contains within it the same elements
that enter into the structure of animal and vegetable
organs. A physical cosmography would, therefore, be
incomplete if it were to omit a consideration of those
forms, and of the substances which enter into solid and
fluid combinations in organic tissues, under conditions
which, from our ignorance of their actual nature, we
designate by the vague term of vital forces, and group
into various systems in accordance with more or less
perfectly conceived analogies. The natural tendency of
the human mind, involuntarily prompts us to follow the
physical phenomena of the earth through all their varied
series until we reach the final stage of the morphological
evolution of vegetable forms, and the self-determining
power of motion in animal organisms.” (Humboldt
Cosmos, vol. 1, p. 348. Otte’s translation.)

Page 9.—Nägeli appears to me to have treated more
profoundly than any other modern author on the limits
of the two organic kingdoms, (Ueber die gegenwärtige
Aufgabe der Naturgeschichte, inbesondere der Botanik.
IT, Th. Zeitschr. für wissenschaftliche, Botanik. II Heft.,
1845.) But yet objection may be made as to the
differential character established by him, of a cellular
membrane, ternary in the vegetable, quaternary in the
animal: the primordial utricle of the permanent vegetable
cell in the Algze (amylid-cell of Kützing), which, like the
nucleus to which it is always connected, consists of a
quaternary azotised substance, is sometimes, perhaps, not
even accompanied by a ternary membrane (gelin-cell of
Kiitzing) ; the cellulose itself becomes permeated by nitro-
genated matter (Payen, Kiitzing); and finally, an abun-
dant ternary substance, isomeric with starch, is present in
the organisation of animal beings, (Schmidt, Loewig,
Kolliker.) The suggestion of Nägeli that the chief
cause of animal sensibility and mobility, resides in that
characteristic (quaternary, azotised) quality of the cell-

506 ANIMAL NATURE OF DIATOMEE.

wall, seems confirmed by the valuable observations of
Kiitzing, already referred to, respecting the mobility of
the inferior Algz, of sporidia, of spores, and spirilla. But
even if we admit this idea, we can deduce no other than
the following principle from the facts hitherto known.
The primordial vegetable cells (internal or naked pri-
mordia! utricle), have, like animal cells, the wall con-
stituted of a quaternary azotised substance, and possess
a mobility similar to animal mobility. Yet there remain
material differences in the contents. But, if this were
not so, if observation failed to detect a material difference
between the rudiments ( primordia) of the two kingdoms,
no one, from that circumstance, would have a right to
maintain that the difference does not exist. When we
compare together the rudiments of plants, or those of
animals, do we find material differences corresponding to
the almost infinite varieties of form and organisation which
ensue with successive development? It is necessary to
repeat, that our senses are limited, and that if we desire
to pass beyond those boundaries by powers of reasoning,
we may do this by no other means than reliance upon
other facts exactly observed. ‘Taking advantage of in-
stances in which the power of our senses is improved, we
reason upon others where that power is more limited.
Thus, in respect to the rudiments of organic beings, the
observation of their successive development proves that
even when those rudiments do not manifest material
differences to our senses, these still exist.

Still we ought, in every way, to be extremely cautious
in deducing anything from these observations which may
seem to prove the animal nature of vegetable germs, even
when they are made with great accuracy; inasmuch as
we can controvert them by others equally exact of a con-
tradictory nature. Such are those made by Nägeli upon
his Conferva glomerata, var. marina, and upon the Achlya
prolifera. In the former, especially, he could trace the
entophytic development of the Bodo viridis, which, at a
certain period, almost exactly resembles sporidia, but

ANIMAL NATURE OF DIATOMEER. 507

does not at all participate in the successive changes that
these undergo in germination.

Page 10.—Nägeli has digested in an able manner all
the facts relating to vegetable movements. The first
series of movements is intimately connected with growth,
and in regard to this we do not possess sufficient data to
establish a general difference between the two organic
kingdoms. The second is referable to the different
positions assumed. by various organs of plants under the
influence of external agents; and those movements are
explained by an accumulation of juices in determinate
tissues, excited by these agents, or by the elasticity of
the cellular membrane. The movements of individual
parts of certain organs are mechanically produced by the
desiccation or intumescence of various tissues. But still
the question remains almost untouched in respect to the
locomotion of the inferior Algze, sporidia, spores, and
spirilla. The impulse communicated by endosmosis and
exosmosis, has certainly a large share in the phenomena ;
but, after all, there remains the fact of vibratile cilia,
which seem to take part in these movements.

Page 12.—The Protococcus and Gregarina are beings
that ‚present the greatest degree of simplicity in their
permanent state. Though, down to 1842, I had limited
the genus Protococcus to those vegetable beings only
which really present the greatest possible simplicity, other
authors, and Kützing in particular, continue to insert
species of more complicated organisation; hence some
confusion is created whenever we refer to this example
of organic simplicity.

Tadmit into the genus Protococcus only thosevegetables
which, according to our means of observation, are reduced
to a simple cell. When the period of reproduction arrives,
the wall of this cell is either reabsorbed, or is lacerated,
and its contents are poured out; the rudiments of new
individuals make their appearance, which are never visible
in the cavity of the maternal cell. ‘The development of

508 ANIMAL NATURE OF DIATOMER.

new individuals occurs, on the other hand, inside the
maternal cell of Chlorococcus and Hamatococcus.

The genus Gregarina was proposed by Dufour, and
very well described by Siebold. Kölliker examined six
species (Die Lehre von der thierischen Zelle. Zeitschr. für
wissenschaft. Botan. II Heft, p. 40.) They are simple
cells, containing very minute granules (granelli), small
drops of oil, and a central vesicle filled with a transparent
liquid, with a few oily drops, and a dark round nucleus.
They move by the expansion and contraction of the
cellular wall. Their reproduction is effected by an endo-
genous cell-formation. The contents separate into two
globular portions, which accumulate around two nuclear
vesicles newly produced; the membranes form round
the two globules, and thus arise two filial cells, which,
after the redissolution of the maternal cell, separate from
each other and begin to enjoy their individual life. The
same author supposes that some species of Bodo, Monas,
Spirillum, Vibrio, &e., equally belong to this new family
of Unicellular Infusoria, but we have no direct observations
to prove this.

Page 13.—Collecting together all that has hitherto
been observed as to the first origin of cells, the supposition
we are able to form is the following. The first elements
we are able to perceive are the so-called elementary
granules (granell) in animals, and the mucous granules
in plants. These are very minute solid corpuscules, of a
quaternary azotised substance, capable of growth, but not
of multiplication, nor of ulterior development. In the
midst of these appear the nucleoli in plants. Around
every nucleolus, mucous granules collect together, forming
a species of crust. The body resulting from this is a
nucleus or cytoblast. Around this appears a membrane
of a quaternary azotised substance, which is the so-called
primordial utricle. Upon the external surface of this,
a membrane of ternary composition, not azotised, is
organised ; this is the true cell-wall, which alone remains

ANIMAL NATURE OF DIATOMER. 509

after the primordial utricle and the nucleus have dis-
appeared. Whatever may be the mode in which the new
cells appear, we may assert, on good foundation, that the
previous formation of a nucleus is constantly followe |
by the primordial utricle, and in consequence by the
cellular wall. The uncertainty and variety are referable
to the first formation of the nucleus, to the contents which
remain confined, or are successively formed between the
nucleus and the primordial utricle, and to the mechanism
forming the cell wall. It is not yet decided whether this
origin of the cells is exclusively endogenous, or may not
even be exogenous. Recent inquiries as to the nature of
yeast, (Hygrocrocis, Leptomitus, &c.,) seem to prove that
nuclei alone, or, perhaps nucleoli, may separately give
origin to cells. In such acase the mucous granules would
be foreign to the new plant, and would contribute imme-
diately to its formation ; the nucleoli would be its germs.
Every one sees the difficulties that are to be encountered
in this research, the cautions that are to be used in
drawing conclusions from every fact observed, and the
necessity of advancing always from the known to the
unknown. Hence, in denominating the organic elements
which are before our eyes, we are not to commence with
what appears the most simple, but rather with that which
is decidedly organised and clearly characterised.

In animals, besides the solid elementary granules
already referred to, there are small vesicles incapable of
ulterior growth and reproduction. They are simple
drops of oil enveloped in a stratum of coagulated
albumen, and may be imitated artificially. Other vesicles
are capable of growth, but not of multiplication. They
contain liquid albumen, and one or more oily drops, as,
for example, the vitelline vesicles. Perhaps they are
analogous to globules of chlorophyll in plants, or those
of starch.

The nucleoli are vesicles similar to the preceding;
they consist of a contained fatty substance, and an
envelope of proteine. They are susceptible of growth

510 ANIMAL NATURE OF DIATOMES.

and multiplication, which takes place by division. Their
original formation is as yet unknown. The nuclei are
vesicles formed of albumen or fibrine, or perhaps of
caseine, containing, besides the nucleolus, an albuminous
liquid, oily drops, and elementary granules. The forma-
tion of nuclei is entirely obscure; but it seems proved
that it cannot take place without the persistence of the
nucleoli. The nuclei are multiplied endogenously, and
in consequence of the multiplication of the nucleoli.
The contents of the nucleus collect round the nucleoli
originating from the division of the primitive nucleolus,
constitute their partial integument, and set them free by
the reabsorption of the maternal vesicles. ‘The nuclei
are not only capable of uniform growth, and of multiplica-
tion, but also undergo numerous modifications, especially
conversion into fibre. The cells have walls soluble in
acetic acid, and are, therefore, composed of a combination
of proteine, either simple, or penetrated with horn,
gelatine, chondrine, calcareous salts, &c.; and they
contain, besides the nucleus, water, albumen, fat, ex-
tractive matter, salts, and other compounds peculiar to
the various organs.

Whether the formation of the animal cell be endogenous
or exogenous, it requires the pre-existence of the nucleus,
upon which the membrane begins to appear, which by
degrees separates and dilates, surrounding it, and holding
it adherent to a point within its wall.

More rarely, the formation of a cell takes place within
a collection of granules having a nucleus in its centre.
The gelatinous substance which superficially surrounds or
unites and amalgamates the granules, becomes coagulated,
so to speak, and is consolidated into a cellular membrane.

These particulars are mostly taken from the work of
Kölliker, in which there may be found a critical analysis
of the physical and chemical theories proposed by authors
to explain the facts adduced.

Page 16.—Nageli gives an ingenious explanation why
the multiplication of cells is always endogenous in

ANIMAL NATURE OF DIATOMEA. 511

plants, and exogenous in animals. He supposes that
the quaternary azotised substance acts catalytically on
the circumjacent materials to produce organisation. In
animals, therefore, the cellular wall acts upon the extra-
cellular materials ; whilst in vegetables, the ternary gela-
tinous envelope being once formed, the catalytical action
of the nitrogenous portion is limited to the interior of
the cell itself. We are indebted to Mohl for the discovery
of cells that remain permanently limited to this membrane
alone, (so called amylid-cell,) and thus we find an ex-
planation consistent with this theory, and also with the
facts recently observed in the development of yeast.

Though it be true that systematic distinctions are
always baffled by nature when they are based upon the
materiality of characters taken absolutely, it is yet true
that general laws admit of uo exception, and that a single
one would suffice to destroy their generality. The
appearance of exceptions proceeds from the complication
in which natural facts occur, a complication that frequently
disappears, when, instead of characters taken absolutely,
we obtain a view of the organic and vital conditions
which give rise to them.

Page 20.—The Tabasheer of the Bamboo, which con-
sists almost entirely of pure silex, seems to be a product of
simple excretion, and therefore in its nature inorganic.
But in all other cases in which the presence of silex is
manifest in plants, as in the epidermis of Graminez,
Palms, and Zguiseta, the part which it takes in the forma-
tion of the cell-wall is undeniable.

The stomatic cells of Huwiseta merit particular attention,
both from the silex they contain, and the transverse strize
they present on the internal surface. This resemblance
to the shield of Diatomeze might lead us to believe that
we ought to regard it as an argument for maintaining
the vegetability of the latter. I do not think that I
ought to dwell upon such an objection; I only notice it
because I would not appear to be, or pretend to be,
unacquainted with it. Yet it seems to me important in

512 ANIMAL NATURE OF DIATOMEE.

another point of view, the apparent complication that the
simple cell-wall may assume when penetrated by silex.

Page 22.—In the description of Diatomez it often
happens that the valves are confounded with the surfaces.
The surfaces are remarkably distinguished by established
characters into primary and secondary. In descriptions,
it appears to me right to admit, for the sake of brevity,
the denomination surface (faccia) for the primary, and
side (lato) for the secondary. But the valves do not
exactly correspond to the surfaces. The lateral valves
are never absent; they sometimes exist solely, as in
Pyzxidicula and Podosira. In many cases, principally
in Achnanthez and Melosiresx, the lateral valves are so
bent or curved as to form parts of the primary surfaces.

But the valves, which exactly correspond with the
primary surfaces, are seldom distinct; and perhaps even
where there is an acute angle for a boundary, as in
Navicula, we cannot say that there is a complete dis-
junction. In most cases, the two primary surfaces, and
therefore the corresponding valves, unite into a continuous
plane, with a re-entering curve. The distinction of ter-
minal surfaces, very evident, especially in the Surirelleze,
is most important. When there are distinct terminal
surfaces, the primary surfaces are very limited. But
these terminal surfaces may belong to the primary valves,
or the secondary, or lateral. If we take the Eunotiez, it
seems evident that the more or less acute or obtuse
extremities belong to the lateral valves, and therefore
the two primary remain entirely separated. But in the
Surirelleze, these seem again to belong to the primaries,
and to participate with them in the process of de-
duplication.

Page 23.—The solid products which, under the form
of incomplete diaphragms, project into the inner cavities
of Biddulphia and Terpsinöe, belong to the lateral valves.
I can say nothing of Climacosphenia, but in the Isthmia
nervosa we have something similar, though less developed.
I think we may also refer the septa of Actinoptychus to

ANIMAL NATURE OF DIATONLZ., 513

the same. Perhaps Zerpsinde may be placed by the side
of Biddulphia in the Family of Melosire, by the same
character. ‘heir principal difference from Vitte, is in
their transverse as well as longitudinal direction. The
Vitte belong to the primary “valves as well as to the
surfaces. These peculiarities of structure are certainly
very important, because we must reasonably suppose that
they bear a direct relation to the internal organisation of
these beings.

But if we consider that in the same genus (Jsthmia),
we have two species very similar to each other, one of
which always presents those incomplete diaphragms,
whilst the other is always devoid of them, we are of ne-
cessity led to exclude this character from the basis of
classification.

Page 25.—The colourless membrane, which connects
all the internal organs of Diatomez together, constitutes
the principal portion of their body, as Ehrenberg has
well observed in many places. Its transparency impedes
our view of its organisation. It seems that the vesicles
observed by Ehrenberg in some species, and supposed to
belong to the male organs, were directly hollowed out of
this substance. Their dilatation and contraction seem
rather to indicate a respiratory function. I believe the
tube that runs longitudinally from one extremity of the
Navicule to the other, and perhaps represents their
organ of digestion, to be hollowed out, in like manner,
from this substance, and void of a proper membrane.

Page 90.—In the Ceratoneis Fasciola, Ehrenberg
describes and figures a distinct median aperture in the
centre of the lateral surfaces.

Page 106.—Kützing, in the Phycologia Germanica,
assigns to the Navicule of Micromega pallidum, instead
of 3d of a line, 3th = 0'034”.

33

ON THE

NATURAL HISTORY

OF

PROTOCOCCUS PLUVIALIS.

By FERDINAND COHN.

[Abstracted from the ‘Nova Acta Acad. Cs. Leop. Carolin, Nature,
Curios. Bonu,’ tom. xxii, pp. 605—764, 1850.]

By GEORGE BUSK, F.R.S.

ON THE

NATURAL HISTORY

OF

PROTOCOCCUS PLUVIALIS, Kurz.

Hematococcus pluvialis, Flotow.
Chlamidococeus versatilis, A. Braun.
Chlamidococcus pluvialis, Flotow and A. Braun.

Tue author commences his paper by referring to the
observations of Flotow, on the same subject, under the
name of Hematococcus pluvialis, (‘Nova Acta Ac. C. L.
C. N. C.,’ vol. xx, p. 11,) and to which he assigns the
highest merit. He proceeds to give an abstract of
Flotow’s observations as an introduction to his own.

However various the metamorphoses undergone by the
Hematococcus in the course of its development, they
may, nevertheless, be referred to two principal forms,—
the stil! and the mote. 'The former, 1. pluvialis quies-
cens, forms a sort of crust on the margin and bottom of
the vessel in which it is kept; the other, ZZ. pluvialis,
swims about in the water.

The motile form is from 0°0003 to 00012 of a Paris
inch in diameter, and consists of a colourless mucous
envelope, probably open in front, within which is con-
tained the true mother-cell, and which is either centric
or excentric. The contents of the latter are grumous
and vesicular, and either altogether of a carmine red

518 THR NATURAL HISTORY OF

colour, or of one inclining to blood red or green, with a
central, multiform, red nucleus ; seldom altogether green.
The mucous envelope is frequently wanting, or is so
closely applied to the cell as to be scarcely apparent.
The red nucleus appears to have a special coat, which,
however, probably does not exist ; it appears as a hollow
vesicle, placed on or near to the inner surface of the
wall, and presents on one side an opening, or, only
half or two thirds of it may exist. The nucleus is de-
tached by pressure, and in the spot where it was situated
appears a colourless vacuity. The anterior extremity of
the mother-cell exhibits either none, or cobweb-like pro-
cesses, which are but seldom apparent, particularly in the
globular or ellipsoidal forms which represent ZZ. pluv.
rotundatus. Or there exists, at the anterior extremity, a
wart-like transparent process, from which arise simple or
bifurcate, filamentous elongations or tentacles, as in the
form ZZ. pluv. papillatus. When this process is conical
and attenuated we have Z. pluv. rostellatus. Not un-
frequently short setose hairs spring from the periphery
of the mother-cell, stretching across the space between
this and the mucous envelope, and which characterise
IT, pluv. setiger.

These motile forms, which may be comprehended
under the common name of 77. pluv. versatilis, are trans-
formed into the still form, becoming round, and retracting
the various processes above noticed; whilst the mucous
envelope is condensed into a papyracous membrane.

This still Hematococcus pluvialis, quiescens, aquaticus,
genuinus, from 0:0001 to 0:0029 Paris inch in diameter,
forms loose masses without its being retained, however, by
any special mucous hypothallus. It sometimes has, and
sometimes has not a mucous envelope ; the mother-cell is
either entirely filled by the sometimes grumose-granular,
sometimes grumose, or even gelatinous contents, so that
the boundary line is reduced to capillary thickness or is
completely obliterated ; or it is only partially filled, and the
contents then form a smaller and, most usually, central

PROTOCOCCUS PLUVIALIS. 519

globular mass, which is probably contained in a second
cell. ‘This was evident, however, in only one case.

As more intimate constituents of the contents, both in
the still and in the motile form, numerous more minute
spherules are to be considered. The red formative
material is to be referred to the sphere of fructification,
the green to that of vegetation. Consequently the green
spherules in Hematococcus must be regarded as germ
granules, or gonidia, which, when larger and internally
organised by a cell nucleus, become green gemmules.
When these gemmules, in the form just described, escape
from the mother-cell, they resemble the innumerable
dependent forms commonly associated under Protococcus
Monas ; they exhibit an instance of retrograde meta-
morphosis, producing a succession of similar organisms,
which, shooting out in succession in a longitudinal direc-
tion, constitute confervoid filamentous forms, or, sprouting
out, expand into Ulva-like growths. Amongst the latter,
one is very remarkable, foliaceous, of a quadrangular
figure, consisting of many cells, which, like a simple
Hematococeus cell, is carmine red in the centre and
green towards the margin.

The green gemmules, however, are capable of pro-
gressive development, destined to reproduce the Hemato-
coccus at once, when, for instance, the mdividual to which
they belong possesses sufficient red formative mucus
for its penetration and fructification. This is apparent
from the circumstance that the two-coloured, still forms
which are entirely filled with red and green gemmules,
in process of time become altogether red. And in this
case the red coloration gradually extends from the central
nucleus, as its original seat, towards the periphery,
whilst in the retrograde metamorphosis the red colora-
tion of the globules proceeds from without to within.

In whatever way the spores formed of this red sub-
stance escape, they develop themselves, and at an un-
favorable time of year and dormant condition of vitality,
float, in flocculent aggregations, on the surface of the

520 THE NATURAL HISTORY OF

water. ‘hey then increase in size, become organised
internally, and surrounded with a membrane derived
from a thickening of the peripheric layer of the spores.
They are thus transformed into A. pluv. atomarius,
which, in the course of further development, becomes of
a rose-red colour and gelatinous, surrounded with a
mucous envelope, and constitutes the form of HZ. pluv.
mucosus ; which is finally transformed again into the
normal form. The dispersion, therefore, of the red
spores is not a proceeding without object, or a morbid
process, but subservient, in an incredible degree, to the
multiplication of the plant.

In a favorable season, and when the vegetative powers
are in full activity, the spores, after their expulsion,
remain adherent to each other, connected by a mucous
material, afterwards becoming free, and successively trans-
formed into the motile form of Hematococcus.

Another motile form is of a smaller size, distinguished by
its active motion, and characterised as ZZ. pluv. porphyro-
cephalus. It has a fask-like or obovate form, 0:0002—
0:0004 Paris inch in length, with a red capitate projection
at the anterior extremity, and ventricose posteriorly. _

In general, from the motile condition all these forms
pass immediately into the still form. But the alterna-
tion between the still and motile forms depends alto-
gether upon external conditions, and is by no means
capricious. Whether the still form, upon its division,
develop motile individuals, depends upon the light and
temperature.

Multiplication by division (status viviparus) occurs
both in the still and in the motile forms. ‘The contents
of the mother-cell, surrounded by a mucous envelope,
divide into four (frequently more) portions, each of
which includes a central particle of red matter, and sur-
rounds itself with a gelatinous membrane.

The division frequently commences in the motile con-
dition, and continues in the still. The younger indi-
viduals, with red mucous globules, spores, buds, and

PROTOCOCCUS PLUVIALIS. 521

green gonidia, and consequently furnished with all the
requisites for existence, burst the mother-cell, and become
free. Should they belong to the second generation, and
consequently arise from the division of already motile
cells, the young individuals frequently remain in con-
nexion, and revolve together until at last they become
detached from each other. From this circumstance
arise aggregations of 4, 5, 6 minute globules; even 8
individuals occur together in a mucous envelope. Some
cells divide even into 12 or more, and revolve in com-
mon like a Volvow.

Other forms of division are noticed. Besides this
mode, multiplication by gemmation takes place, both in
the still and motile forms (innovatio). Within the
mucous envelope there is formed a parietal, colourless
vesicle, into which the red atoms pass from the mother-
cell, and thus gradually colour the young individual.

The author proceeds to describe the effects of desicca-
tion, &c., upon the appearance and colour of the varieties
of Hematococcus, and notices the extraordinary power
of vitality after desiccation for many months, when the
Hematococcus has been slowly dried; and even after
quick drying, it would seem that development is possible
by means of spores and gemmules from the form named
H. atomarius. And even in some cases after such indi-
viduals had been swallowed and evacuated by Infusoria,
for instance, by Philodina roseola. Even momentary
exposure to a boiling temperature does not destroy their
vitality altogether, though it does so partially.

A summer temperature, however, very much pro-
motes the development of the Hematococcus, so much
so, in fact, that occasionally all the stages are gone
through within eight days. Commonly, the motile forms
retain that condition only for afew days or hours. When
some in the motile form are placed in a glass of water,
within twenty-four hours a red border appears at the
margin of the water as it evaporates, consisting of still
vesicles undergoing division, whilst beneath it is a

522 THE NATURAL HISTORY OF

broader, greener, reddish band containing the motile
individuals. The motions of the various forms of Hema-
tococcus are then described, (p. 623,) and, from the
description, appear to be very like those of Euglena
viridis. In fact so much so that Flotow himself com-
pares them with those of Astasia pluvialis, deeming,
however, that species, which is either identical with, or
closely allied to Zuglena, as an animal Infusorium. He
goes on to say, however, “that there is no appearance,
in the Hematococcus, of animal organisation, particularly
of a mouth, intestine, or stomach ; nor is the admission
of indigo into the interior ever observed.”

Flotow considers that the source of the motion of the
globules of Hematococcus is quite problematical.

Having thus premised an abstract of the more impor-
tant points in Flotow’s researches, from which the above
are extracts, the author proceeds to detail his own obser-
vations, which he says are to be considered only as
supplementary, in a great measure, to those of Flotow,
which he regards as of the highest value.

On the 2d January, 1850, some particles of sand
containing Protococcus pluvialis which had been collected
by A. Braun, were placed in a deep glass vessel and
covered with snow-water. The first moving forms were
noticed on the Sth of January. The Protococcus had
been in a dry state in the herbarium for two years.
Other experiments showed that this retention of vitality
endured through many years.

In his experiments the author found great convenience
in the employment of little glass vessels in the form of a
truncated cone, about two inches deep and one inch and
a quarter in diameter, with a flat bottom polished on
both sides. These little vessels were filled with water to
the height of two to three lines. It was only in vessels
of this kind that he was able to follow the development
of a number of various cells throughout its whole course.
Although he agrees in the maim with the views expressed

PROTOCOCCUS PLUVIALIS. 523

by Flotow, the author differs from him, at the com-
mencement, in one important particular. Flotow looked
upon Protococcus pluvialis as a multicellular plant, the
individual cells of which are held together by a common
parent vesicle. Although he does not express himself
particularly with respect to the kind and mode of this
connexion, it may be taken that he regarded it some-
thing like that which obtains in Nostoc, or rather, per-
haps, like the structure of Polycoccus punctiformis, Kutz.,
in which numerous cells are said to be surrounded by a
thin, common cell-membrane. (Kütz., ‘ Phycol. Germ.,’
p- 148.)

This view, however, is undoubtedly erroneous. The
P. pluvialis is in all its phases a unicellular plant.

The idea of a unicellular plant, as first propounded by
Nägeli, as a systematic principle (‘ Gattung. einzelliger.
Algen.’ Zurich, 1849,) does not apply throughout to the
extent in which he employs it. He certainly includes
under the term a number of genera, having a certain degree
of internal relationship, as indicated by the fact that pre-
vious phycologists had united them in large natural
orders, (Chamephycee, Kg.; Ulvacee, Harvey; Palmellee,
Decaisne, Endlicher, &c.) On the other hand, the
definition of a unicellular Alga, “that in it the indi-
vidual is a single cell,” is too wide or too narrow, (I. c.,
p. 1.) Too wide, because this definition may be applied
with equal right to other Algz, which must be reckoned
among the multicellular, such as Zdogonium, which is
a Conferva, or Prasiola, one of the Ulvacez, as Desmi-
dium and Gallionella, or as Tetraspora, all of which are
declared to be unicellular Alge. ‘I'oo narrow, because it
is only by straining the definition that such things as
Pediastrum, Spherastrum, which form definitely bounded
bodies, and many Palmellee, can be included under it.
Just as little do the characters assigned to a unicellular
plant bear a comparative scrutiny. ‘The unicellular Algze
are said—]. to present merely a reproductive, and, nor-
mally, only a double kind of cell-formation ; this is, how-

524 THE NATURAL HISTORY OF

ever, contradictory to the doctrine of Alternation of Gene-
rations, which is extensively applicable among the organ-
isms in question. For it is only after a series of divisions
that the true reproductive formation of spores takes place.
And Closterium, or Eunotia, which, after numerous divisions,
produce true spores by conjugation, differ from Spirogyra
and Ulothriz solely in this, that in the latter the parent-
cell, which connects each pair of divisional individuals,
being converted into a cuticular substance, is persistent,
whilst in the former it is soon dissolved. Whence it
is also incorrect to say—2. that unicellular Alge are
normally separate and without organic connection, be-
cause the containing and interstitial gelatinous substance
should not be regarded as such. At all events I have
been unable to perceive any essential distinction between
the enveloping substance in Fragillaria and Mougeotia,
genera which are equally readily separable into distinct
cells, and in Nostoc and Apiocystis.

As far as this, therefore, I agree with the reviewer of
Nägeli’s observations, (in Mohl and Schlechtendal’s
‘Botan. Zeit.,’ 1849, Nos. 41-45,) but when he goes on
to assert “that there are no such things at all as uni-
cellular Algze, and that each cell is only part of a system
of cells contained one within the other, (1. ¢., p. 801,) it
is impossible for me to coineide with him.

There are, undoubtedly, unicellular Algee, that is to
say, Algee, the fluid contents of which, sometimes con-
taining already organised particles, are enclosed in a
single, semifluid, nitrogenous envelope, and this again in
a cell-membrane, often consisting of several layers of
different kinds; and which, moreover, possess the faculty
of dividing themselves into several secondary cells, for
the most part equivalent to the primary cell. To these
unicellular Alge belongs Protococcus pluvialis.

That this is the case is most clearly seen in the still
form, which is most distinctly characterised by its cell
membrane, a more or less thick, though always colour-
less, envelope. In some cases it is gelatinous, and then

PROTOCOCCUS PLUVIALIS. 525

surrounds the contents with a broad, peculiarly refrac-
tive ring, (Fig. 33.) In cases where this tunic does not
exhibit a double contour line, it is manifested by the
dark and sharp border surrounding the contents, and
which, especially on the transition of the motile into the
still form, is the first and most certain criterion of the
incipient change. ‘Thus it resembles the membrane of
many Protococcace and other Alge. It never secretes
true thickening layers on the surface. Although this
cell-membrane exhibits all the optical characters of one
composed of cellulose, I have found it impossible to
demonstrate the presence of that principle by means of
iodine and sulphuric acid; it is not coloured by those
reagents even after the contents of the cell have been
expressed. But this does not show that the membrane
is not of a vegetable nature, because other Protococcaceze
behave in the same way; nor can cellulose, by those
reagents, be shown to exist in Oscillatoria, Nostoc,
Merismopedia and other unicellular Alge.

The still cell always assumes a deep, almost black
colour, upon the application of a watery solution of
iodine; but this does not depend upon the coloration of
the cell-membrane itself, but upon the circumstance that
the nitrogenous contents, coloured by the iodine, are
seen through the transparent tunic.

The contractility of the contents when exposed to the
action of acids or alcohol, proves that they are endowed
with the same properties as the primordial utricle of Mohl,
the amylid-cell of Kützing. But there is no evidence of the
existence of any special layer of the contents, which could
be exclusively designated as a ‘‘ primordial sac ;”’ it would
much rather appear as if the entire contents of the cell
(endochrome of authors), in most cases, were to be regarded
as essentially homogeneous, and that it is only the outer-
most, for the most part densest peripheral portion of them
which possesses the faculties, which in other plants, par-
ticularly in the large-celled Algz, appertain to an also
optically distinct layer. (Vide ‘Ueber die Rotation des

526 THE NATURAL HISTORY OF

Zellsaftes, in Mitella flewilis; by Göppert and Cohn,
Botanische Zeitung, 1849, No. 37—40.)

There are, however, phases of development in which
the colourless or almost aqueous cell-contents can be dis-
tinctly defined from the denser, coloured, gelatinous,
peripheral substance. Whilst, therefore, in most cases,
the still form, according to Kützing’s terminology, would
have to be regarded as hologonimic full-cells, in which
the solid contents completely fill the cell, so, when the
primordial sac and cell-juice are separated, they would
necessarily come under the denomination of celogonimic,
hollow cells.

The contents vary very much in consistence, colour,
and solid constituents.

The red and green portions of the contents appear to
be of equal physiological importance.

The green colour is removed by ether, on the evaporation
of which solvent there remain green, ‘afterwards colour-
less drops. Dilute sulphuric acid at first renders the
colour paler; but its prolonged action produces a bright
verdigris hue, which gradually becomes more and more
intense, and often almost a blue green. Hydrochloric
acid has a similar effect; a tinge of brown is produced
by nitric acid. Carbonate of potass scarcely affects the
green colour; it is gradually but totally destroyed by
caustic potass, the contents at the same time swelling
and becoming transparent.

The red colour is also to some extent soluble in ether,
but is less affected, or scarcely at all by any of the other re-
agents above endete. It differs, therefore, from the
erythrophyll or the acidified anthocyanine of chemists, as
well as from the colouring matter of litmus and phycoery-
thrin, which, according to Kützing, is peculiar to the Flo-
ridez. In its chemical relations it seems most nearly allied
to the phycohzmatin of Rytiphlea tinctoria, but the latter
is insoluble in ether. It also seems to be related to the
orange coloured oil, which, according to Nägeli, is formed,
under morbid conditions, in many unicellular Alge.

PROTOCOCCUS PLUVIALIS. 527

The contents -of cells which have been long dried,
generally assume an oily appearance. The oily material,
then resembles in every respect the red globules which
have been described as being oil, in various species of
Chroolepus, such as C. oleiferum, hercynicum, velutinum,
aureum, and Jolithus. Like the latter, also, it is capable
of becoming green.

The change of colour from green to red in Zuglena
appears to be a process very nearly allied to that which
takes place in Protococcus, if it be not identical with it.
Great confusion and much contradiction is evident in
nearly all writers who have referred to the subject of the
colouring matter in plants, and accurate researches on
tle subject would appear to be of the greatest moment.

The red substance of Prot. pluvialis is not always of
an oily aspect ; it only becomes so in more advanced age.
Whether it really be oil, the author does not venture to
decide, although the relation of the material towards
light, alcohol, and ether (and he might have added,
water), are in favour of its being oil. And according to his
researches, oil is much more generally distributed than
has been supposed, among the lower Algze; occurring in
many true brown spores, such as of Cidogonium,
Spirogyra, Vaucheria, &c.

When still or motile cells are brought in contact with
a very weak watery solution of iodine, they become
internally, in most parts, of an intense violet or blue colour.
The author, however, does not believe that this colour
actually, in all cases, depends upon starch, as in the
present state of chemistry it would appear necessary to
conclude that it did. He was satisfied that the red sub-
stance was invariably and entirely coloured blue. When
some of the cells were ruptured, all the previously red
globules had become entirely dark blue, so that the red
colour was wholly removed, whilst the green substance of
the cell with its granules was not so much altered, though
also bluish. The larger drops also appeared blue, so
that there was no difference whatever, in this respect,

528 THE NATURAL HISTORY OF

between their reaction and that of starch, which also fre-
quently occurs in similar small globules. But that the
red, oil-like, or at all events, fluid substance, should be
actually identical with the colourless, solid starch, which
always presents a definite structure, can scarcely be as-
serted. May there not, however, in the Vegetable king-
dom, be a coloured fluid, exhibiting the same reaction
with iodine, in all respects as starch? If this be the case,
the infallibility of the blue reaction with iodine, as a cri-
terion of the presence of starch, would become question-
able ; and, particularly in the case of the unicellular Alge,
in which large-grained starch does not occur, would this
observation be of importance. Nägeli had noticed the
blue colour assumed by this orange-coloured oil on the
addition of iodine, especially when it was collected into
large blue-green drops by means of alcohol.*

Of great importance, moreover, is the relation of the
green and red colouring matters to each other. For,
notwithstanding their different chemical and physical
conditions, the one passes into the other, and vice versd.
The observations hitherto made on this subject, indicate
that the red colour which normally is always formed as
the cells become drier, particularly in moist air, depends
upon a less saturation of the cells with moisture ; 1s the
attribute in fact of a lower hydrate of chlorophyll. But
that a deficiency of water is not the sole cause of the
change of colour, is proved by longer observations of the
vegetation of Protococcus. Nor does light either appear
to be the exclusive cause of this phenomenon, which
remains still in considerable obscurity.

With respect to the solid constituents of the Proto-
coccus cell-contents, they may be distinguished into
chlorophyll vesicles, colourless or green granules, the
above-mentioned amylaceous granules, and the nucleus.

* The yellow oil, of which there is a considerable quantity, in the winter
spores of Volvox, (the so-called 7. aureus, Ehr.,) is colourcd bluc-green by
iodine.—Ep.

PROTOCOCCUS PLUVIALIS. 529

The term chlorophyll-vesicle (chlorophyll-blaschen) was
first introduced into the anatomy of the Alge by Nageli,
although Meyen had previously expressed a similar view
respecting the structure of the chlorophyll. Nägeli
regards them as minute membranous vesicles, containing
a mucus coloured with chlorophyll, only apparently pre-
senting the aspect of nuclei or hollow spaces, frequently
forming starch in their interior, and which are found in the
Palmellaceee, Desmidieze, Vaucheriaceze, and multicellular
Alge. In Prot. pluvialis, they present the appearance of
minute green rings, about 0°002” in diameter, the in-
terior being sometimes darker, sometimes more clear, and
frequently almost opaque. They occur principally in the
green cells, to the number of one, two, three, four, or
more. Rarely observed in the red cells. They are
coloured dark brown or violet, by iodine. The author
supposed that in Protococcus they stood in connexion
with the division of the cell; but could not determine
with certainty that their number corresponded with that
of the secondary cells. Kützing looked upon them as
gonidia or cell-nuclei, assigning to them the function of
propagation of the individual; but Cohn does not coin-
cide in this view, though ignorant of their true nature
with respect to the life of the cell.

The sometimes colourless, sometimes green granules,
are very minute, none being more than 0°001’” in size.
The colourless may be regarded as protoplasma- (mucus,
schleim-) granules, the green as chlorophyll granules,
which latter must not be confounded with the chlorophyll
vesicles.

Whether there be a true cell-nucleus in Profococcus,
Cohn has not ascertained with complete certainty. It is
known, moreover, that in most of the other Algz, and par-
ticularly the unicellular, it has not yet been made out
satisfactorily, whether, in the first place, a nucleus does
occur, and if it does, what its function may be.

The presence of starch has above been stated to be

doubtful.
34

530 THE NATURAL HISTORY OF

Microscopical analysis, therefore, demonstrates, in the
still cells of Protococcus, whatever aspect they may pre-
sent, the following elements :

1. A closed cell-membrane ; 2. contractile, sometimes
colourless, sometimes green, sometimes red, cell-contents :
the latter in innumerable droplets, the two former fre-
quently condensed or separated into more solid granules ;
3. lastly, one or more chlorophyll vesicles, and in certain
stages a cytoblast. All these elementary parts occur also
in the cells of other plants, and there is, consequently, no
difficulty in the referring of all such forms, when in the
state of rest (the special value of which is only shown by
the history of their after-development) to the simple
vegetable cell.

This inquiry, however, is far more difficult in the
case of the much more variously constructed motile
form.

This form was considered by Flotow to consist of a
larger parent vesicle, surrounding numerous smaller red
and green cellules, and itself again surrounded by a
mucous envelope, within which were two tentacula, often
placed upon a beak-like projection.

The first thing ascertamed by Cohn was the non-
existence of the mucous envelope. The optical appear-
ances distinctly showed the existence of, not an enveloping,
at all events fluid mucus, but of a solid membrane.

Although this statement does not accord with the
notions hitherto entertained with respect to similar
appearances of an enveloping mucous layer in other
Algee—which has been regarded by Kützing as a gela-
tinous or mucous envelope, consisting of jelly (gelin), and
termed by him a gelatinous cell (gelin-zelle) or tube,
or sometimes amorphous gelatine; and which has been
designated by Nageli as an “enveloping membrane (hüll-
membran), who supposes its outer layer to consist of a
homogeneous, semifluid gelatinous substance,—Cohn
states, that at all events, in the case of Profococcus, a struc-
ture so abnormal and different to what exists in all other

PROTOCOCCUS PLUVIALIS. 531

plants, does not ocour. The central coloured globule,
lying in the colourless envelope, is certainly sharply
defined, but not as in the still cells, surrounded with a
strong double contour line, but with a delicate simple one,
which gives it a peculiar soft appearance. Hither by me-
chanical means, or by chemical reagents, the internal
globular mass may suddenly be made to lose its contour,
and to spread so as entirely to fill the cavity of the colour-
less envelope. From which it would appear that the
internal globular body is not surrounded by any special
cellulose-membrane, but only by one readily destroyed
by chemical or physical agency, probably nothing more
than a dense layer of protoplasm. Whilst, on the other
hand, the external membrane represents a true cell-
membrane, enclosing between itself and the coloured
substance a colourless, aqueous fluid, probably pure or
nearly pure water.

The motile form of Protococcus, therefore, consists, as
it were, of two cells, one within the other, both of which,
however, differ essentially from the common vegetable
cell: the external having a true cell-membrane and
aqueous contents; the other, or internal one, with
denser, muco-gelatinous, coloured contents, but without
a true, rigid (starre) cell wall. Cohn proposes to call the
external transparent vesicle the “enveloping cell” (hiill-
zelle), and the internal coloured one, the “ primordial
cell.” The term “primordial sac, or utricle,” which
nearest corresponds to this organism, can only be applied
to its peripheral layer, and not to that together with the
contents; and the term “amylid-cell” of Kützing in-
volves a chemical error.

Neither of these bodies are true, perfect cells, inasmuch
as the former wants the primordial utricle, and the second
is without the true cell-membrane. The two together
would represent the perfect cell; and the entire aspect
corresponds, externally perhaps, to a plant-cell in which
the primordial utricle has become detached from the cell-
membrane and contracted itself into a globular mass in

532 THE NATURAL HISTORY OF

the interior. But in the present case the course of
development is completely opposed to this view.

On the other side, again, the primordial cell corresponds
to the cytoblast of the common plant-cell, not only
because, like that, it is free, and for the most part excentric,
floating in the interior of the cell, but also in its relation
to the development of the cell-membrane, in which it
agrees in its function with that assigned by the theory of
Sclileiden and Schwann, to the nucleus, in the formation
of the cell-membrane.

The form of Protococcus, named by Flotow Hem. pluv.
versafilis setiger (fig. 15), presents a perfect analogy
between the primordial cell and the nucleus of the
common plant-cell. He states that the filaments which
proceed from the central mass to the peripheric cell-wall,
are tubular, giving passage to the red molecules from
the central mass. These filaments, however, which pro-
ceed from the outer wall of the primordial cell towards
the inner surface of the enveloping cell, correspond mor-
phologically to the so termed mucous filaments (sap-
streams) by which the cytoblasts are commonly retained
in the centre of their cells. ‘That they also correspond
chemically with these, is proved by the fact that they are
rendered more distinct by iodine, and that they can be
made to retract by means of reagents ; and, in fact, they
exhibit, in the course of development, peculiarities which
characterise them as consisting of protoplasm.

The existence of these delicate threads passing from
the central mass to the enveloping cell, and the appear-
ance occasionally of little particles having molecular
motion, serve to show that the contents of the enveloping
cell are not of a gelatinous consistence, but of an aqueous
nature. And the continuity of the primordial cell-wall
with the filaments shows that it is surrounded only with
a denser layer of protoplasm, and is not enclosed in a
rigid membrane of cellulose.

The form versatilis, therefore, of Prot. pluvialis is
to be regarded as a cell with clear aqueous contents, in

PROTOCOCCUS PLUVIALIS. 533

which a central, also cellular, mass of protoplasm, or a
primordial-sac-like organism, performs the part of a
nucleus.

The most distinctive characteristic of the primordial
cell, and what appears to constitute its most essential
importance in the life of the cell in general, but particu-
larly in that of the Zoospore (schwärm-zelle), consists in
its being the contractile element of the vegetable or-
ganism, that is to say, that from an intrinsic activity it
possesses the faculty of altering its figure, without any
corresponding change in volume.

It was Ehrenberg who first asserted that there was an
absolute boundary between animals and plants ; finding
even, as he fancied he did, in the smallest of the former,
—the Infusoria,—which had previously been regarded
as mere unorganised masses of mucus, the same systems
of organs as those by which the most highly-developed
animal is characterised, that is to say, distinct nutritive,
motile, vascular, sexual, and sensitive systems. Siebold
called the existence of these organs in question, regarding
the organisation of the Infusoria as a homogeneous pa-
renchyma, in which he recognised only a nucleus, and in
one division a mouth and cesophagus. Nevertheless he
asserted that plants and animals were essentially distinct,
and that there was no transition from one to the other,
the nature of the plant being always immotile and rigid,
whilst the animal possessed the faculty of contracting and
expanding its body. This contractility, he observes in
another place, is the only certain diagnostic character, all
others being invalid.

It is not, however, the animal organism itself which is
contractile, but only a single tissue in it; all the rest, skin,
bones, and connective tissue, are as rigid or passive as
the vegetable membrane, or at most elastic ; in the higher
animals the muscles only are contractile, and only in the
lowest, viz. the Infusoria, the entire body.

Whence Ecker assumed the existence of a special con-
tractile substance, which sometimes occurs in a formed

534 THE NATURAL HISTORY OF

state, as a contractile cell or as muscular substance, some-
times amorphous, as in the bodies of the Infusoria,
Rhizopoda, and Hydroida. Kölliker confirmed this view,
and carried it out particularly in the case of the Infusoria,
which he declared to be unicellular animals with a con-
tractile cell-membrane and contents.

The contractile substance is characterised by the fol-
lowing attributes :—it is homogeneous, or finely granular,
transparent, of the consistence of albumen, gelatiniform,
soft, more refractive than water, but less so than oil;
insoluble in water, but gradually decomposed ; destroyed
by caustic potass ; coagulated and contracted by carbonate
of potass, as well as by alcohol and nitric acid; having
the power of forming aqueous cavities, which originate
either by the separation of the water contained in it, or
by its reception from without; owing to which the
remainder becomes denser and more granular; and,
lastly, it presents the appearance, in water, of contractile
drops, which move like an Amba.

All these properties had already been observed by
Dujardin, in a substance of which the Infusoria and
Rhizopoda are principally composed, and which he
termed “ Sarcode;” the aqueous spaces or hollows he
named “ Vacuoles,” regarding them as the most charac-
teristic feature of the substance; these spaces had been
erroneously regarded by Ehrenber g as stomachs.

All these properties, however, are possessed by that
substance in the plant-cell, which must be regarded as
the prime seat of almost all vital activity, but especially
of all the motile phenomena in its interior—the proto-
plasm. Not only do its optical, chemical, and physical
relations coincide with those of the “ Sarcode,” or con-
tractile substance, but it also possesses the faculty of
forming “vacuoles,” at all times, and even externally to
the cell; a property, it is true, which has for the most
part been hitherto overlooked or misinterpreted.*

* Sometimes, as in the zoospores of Volvox, these vacuoles exhibit
rhythmical contractions.—[En. ]

PROTOCOCCUS PLUVIALIS. 535

These clear, aqueous spaces, the so termed vesicular
contents, are presented in all young cells, and play a
considerable part in cell-division, and the sap-currents ;
they are in all respects analogous to the vacuoles of the
sarcode, as already supposed by Meyen.

From these considerations it would therefore appear as
certain as it can be made by an empirical deduction from
the premises in such a subject, that the protoplasm of
Botanists, and the contractile substance and sarcode of
Zoologists, if not identical, are at all events in the highest
degree analogous formations.

Whence, the distinction between animals and plants,
viewed in the above light, must be thus understood ; that
in the latter, the contractile substance, as the primordial
utricle, is enclosed within a rigid, ligneous membrane,
which permits only an internal motion, evidenced in the
phenomena of circulation and rotation; while in the
former it is not thus enclosed. The protoplasm, in the
form of the primordial sac, is, as it were, the animal
element in the plant, in which it is confined, being free
only in the Animal kingdom. Or, to express the thought
broadly, the energy of the organic vital activity, realised
in motion, is especially connected with a nitrogenous,
contractile substance, which, however, in the plant, is
“ cribbed, cabined, and confined” by a rigid, inert mem-
brane, absent in the animal.

The above motile attributes belong eminently to that
form of the primordial sac to which the author has given
the name of primordial cell, under which term he means
generally to designate that form of the primordial sac which
in itself assumes the figure of acell, and is either entirely
without any rigid cell-membrane, or at least may exist in-
dependent and isolated from it. Such is the case, particu-
larly in the Zoospores (Schwärm-sporen) of the Alge.

This is exactly the condition presented in the primor-
dial cell within the enveloping cell, in the motile form of
Protococcus pluvialis.

The colourless protoplasm often constitutes by far the

536 THE NATURAL HISTORY OF

greater part of the primordial cell, which then appears
as an almost entirely colourless, sharply- defined globule,
owing to the fact that the protoplasm is invariably sur-
rounded, where it is free, by a sharp border, as if by a
membrane. It is only in the middle or at one end of
the globule that there generally remains a deposit of the
green substance in the form of a ring or lateral mass,
(Fig. 26.)

The same colourless protoplasm occurs in all cells,
even where the other coloured substances are much
developed ; especially does it always appear as a delicate,
almost imperceptible layer constituting the outer boundary
of the coloured primordial cell, the periphery of which
then becomes sharply defined, and as it were surrounded
by a delicate, transparent, membrane. (Fig. 16.) Besides
this, the colourless protoplasm seems to occur exclusively
at the anterior extremity of the primordial cell, where it is
produced into a conical elongation or beak. (Figs. 18, 36.)

The green substance appears sometimes as a thin and
fluid, sometimes gelatinous, sometimes more solid mucus,
and is perhaps more abundant and better developed in
the motile than in the still form.

The red substance generally forms only a central mass
of greater or less size; more rarely it constitutes exclu-
sively the contents of the primordial cell. It is interesting
to trace all the stages of the transition from the green
into the red substance, and one stage or phase especially
has long been regarded with great interest, in which
the red pigment is reduced to a single minute granule,
attached to the interior, or to one side of the primordial
cell, then representing what is described by Ehrenberg as
the “red eye spot” of the Infusoria, and which was dis-
covered by Kützing, Fresenius, and Thuret, in the spores
of Alge.

The three substances just considered present themselves
in the form of colourless, red, and green globules,
granules, and drops; but besides these, the primordial
cells contain, at times, vacuoles, chlorophyli-vesicles,

PROTOCOCCUS PLUVIALIS. 537

starch, and larger colourless granules of unknown ma-
terial.

The so termed “vacuoles” occur, in greater or less
number, in the interior of the primordial cells ; they must
be regarded as clear aqueous secretions from the colourless
or coloured protoplasm, which is consequently forced from
the centre of the cell towards the periphery. They are
formed, and change, both in number and figure, under
the eye of the observer, and present the aspect of large,
hollow, clear vesicles, which have the effect of causing
the coloured contents to appear frothy (Figs. 21, 27) ; and
they are frequently developed in such number, that the
coloured protoplasm seems only like a green deposit
on the wall, and even there to be wanting in parts. By
them it is that the internal watery cell-contents, as in the
common plant-cell, become definitely separated from thie
more dense peripheric protoplasm (the primordial utricle).
The chlorophyll-vesicles resemble, in all respects, those
already described in speaking of the still form. They
are occasionally wanting in every form of cell, but gene-
rally so in the more minute, one or two-coloured pri-
mordial cells. (Fig. 41.)

By starch granules are meant, in this case as in the
still cells, very minute, colourless, strongly refractive
particles or granules, rendered blue by iodine, and which,
on the first appearance of the contents, are present in
great abundance in certain stages.

The colourless granules, which were met with only on
one occasion, in almost all the cells in the vessel, espe-
cially in the smallest, were highly refractive, spherical,
transparent corpuscles, visible through the coloured con-
tents. 'I'hey were neither coloured nor changed by iodine,
acids, or alkalies. They resemble similar corpuscles
which occur in Zuglena viridis at certain times.

The author then proceeds to describe the infinite
variety in appearance of different individual cells, owing
to the varying quantities or arrangement of the elements
above described ; almost the only part of a motile Pro-

538 THE NATURAL HISTORY OF

toeoccus cell which is alike in any two individuals being
the enveloping cell.

The anterior projection, beak or rostellum, is.always an
immediate prolongation of the colourless protoplasm,
forming the outermost boundary of the primordial cell,
but into which, speaking generally, the coloured sub-
stance is not continued.

The contractile movements of the primordial cells is
usually very slow, but occasionally more rapid, in that case
very closely resembling those of Euglena viridis. "These
more rapid changes of figure and appearance, take place
particularly upon the partial evaporation of the water in
which the cells are contained. But if this evaporation
proceed further, and fresh water be not added, further
and more important changes take place in the primor-
dial cells of Protococcus pluvialis, which may be com-
prehended under the term of “ deliquescence.” This
process is exclusively characteristic of the vegetable
primordial cell, particularly in all zoospores on the one
side, and also in the Infusoria on the other.

The phenomena in question present two stages or
phases. In the first, the outlines appear less sharply
defined, because the coloured substance is somewhat
retracted from the border of the primordial cell. It
is then clearly evident that the colourless protoplasm
constitutes the special smooth boundary membrane of
the primordial cell. The cells become flattened, and at
the same time wider. The contents also are now
altered; previously more homogeneous and transparent,
they now become throughout granular, and the red sub-
stance runs together into large drops. At this time
commences the formation of vacuoles, the number of
which continues to increase. In this way the interior of
the primordial cell again becomes colourless, clear as
water, and the granular, coloured contents, compressed
against the walls. The figure of the cell, in the mean-
while, is so much expanded that it comes to be applied
upon the wall of the enveloping cell, ultimately filling it

PROTOCOCCUS PLUVIALIS. 539

altogether, (Figs. 27, 28,) so that the entire zoospore
appears to consist of only a single, coloured, granular,
vesicular disc, corresponding in size with the original
enveloping cell.

The Protococcus pluvialis has true motile organs,
namely, two long vibratile cilia arising from the pri-
mordial cell, and which, passing through two openings
in the enveloping cell, move about in the water. ‘These
organs, during the life of the cell, move so rapidly that
it is then difficult to perceive them; they are only
recognisable by the currents they produce in the water.
But when the motion is slackened they are evident
enough. They are also rendered very distinct by iodine.

They are always placed upon the extreme point of the
conical elongation, on the anterior end of the primordial
cell, and in such a manner as to appear to be immediate
continuations of its substance, and as that process itself
consists of protoplasm, it is evident that the cilia must
be regarded also as composed of the same substance.
They appear in some cases to possess an adhesive pro-
perty. ‘They resemble, in fact, in all respects, the so-
called proboscis of certain Infusoria, such as Huglena and
the Monades, and not to differ organologically from the
non-vibratile but retractile filaments of Aconita and
Actinophrys.

It is only that portion of the vibratile filaments beyond
the enveloping cell that exhibits any motion, the portion
within the outer cell is always motionless, and in that
part of their course the filaments appear to be sur-
rounded with a sheath. This seems to be the case,
not only from the greater thickness at that part, but
also from the circumstance, that when, from the pas-
sage of the cell into the still condition, the cilia dis-
appear, the V-shaped, or forked internal portions remain
visible. And it is then, also, that the openings through
the enveloping cell become, for the first time, visible
(Fig. 46.) Such are the “encysted zoospores” (umhüllte
Schwärm-zellen.)

~

540 THE NATURAL HISTORY OF

There are, however, forms in which the enveloping
membrane cannot be distinguished at all, and in general
does not exist: these forms are designated “naked
zoospores” (nackte Schwärmzelle.) They are true pri-
mordial cells; that is to say, their external boundary is
formed of nothing but the contractile cell-contents, or
protoplasm; a true, solid, and rigid vegetable cell-
membrane is wholly wanting. They thus correspond in
their structure with the zoospores of most of the other
Alge (Vaucheria, Gdogonium, &c.) These naked zoo-
spores originate in various ways, and belong to various
stages of development. The following varieties of this
kind of primordial cell may be distinguished.

1. Those which differ from the encysted only in the
absence of the enveloping cell. This form corresponds
with the younger condition of the encysted zoospore,
arising from the division of the cell, around which the
enveloping cell is not yet formed.

2. Another form arises immediately from the still cell,
distinguished by its verrucose figure, and its, for the
most part, cinnabar red colour. It is of small size,
and, narrow in shape (Fig. 32.) On “deliquescence”
taking place, the primordial cell becomes expanded, and
at the same time flatter and of a lighter colour, the
coagulated red droplets exhibiting a lively molecular
motion in the interior. In this case, also, large colour-
less vesicles are then developed in the interior.

In certain conditions, this form of primordial cell
resembles, in its form and aspect, the genus Astasta of
Ehrenberg.

3. Are very minute naked zoospores, not more than
0:002” to 0:005” in size, mostly globular. They con-
tain chlorophyll granules and red droplets, more rarely
chlorophyll-vesicles, and colourless granules of unknown
nature, as described above (Fig. 41.)

4. Perhaps the most remarkable of all the numerous
aspects presented by Profococcus pluvialis, is the form of
naked zoospore named by Flotow Hematococcus porphy-

PROTOCOCCUS PLUVIALIS. 541

rocephalus. It is in the form of extraordinarily minute
(from 0:0015” to 0:004’”) globules, consisting of a green,
red, and colourless substance (protoplasm) in unequal
proportions. The colourless protoplasm, in these, as in all
primordial cells, constitutes the outermost delicate boun-
dary; the red substance is for the most part agglome-
rated towards the anterior end in minute spherules, the
granular green substance occupies more the under part,
whilst the middle is most usually colourless. The shape
varies extremely.

Hence it is apparent that the naked zoospores, although
as regards their development not of equal value, are all
constructed in an analogous manner, varying only in
their mutable form, size, and colour. But they are all
true primordial cells, which before desiccation undergo
deliqnescence, having no rigid, solid, ligneous membrane,
being enveloped only in a mutable layer of protoplasm,
and with colourless green and red contents, in part
organised into granules and droplets, rarely containing
colourless granules of unknown nature, and chlorophyll
vesicles, and always moved -by means of two longer or
shorter vibratile filaments.

Having thus gone over the anatomical description of
the various forms of Profococcus, the author proceeds to
the history of its development.

1. The Protococcus pluvialis is a unicellular Alga, a
simple cell, or at least the individual represents an
organism which exhibits the conditions of a simple cell ;
each multiplication of the cell reproduces the species, and
is at the same time an act of propagation ; each dissolu-
tion of the parent-cell into secondary ones constitutes a
new generation ; each secondary cell is an independent
individual of the same species.

2. The Protococcus pluvialis is a plant subject to an
“alternation of generations ;” that is to say, the com-
plete idea of the species is not exhibited in it until after a
series of generations. The forms of development which can
be possibly comprehended in the idea of the species, do not

542 THE NATURAL HISTORY OF

in reality make themselves apparent until a series of inde-
pendent successive generations has been gone through.

3. The individuals of each such generation are capable
of propagating themselves in new generations. The
individuals of the second generation, are among them-
selves, speaking generally, of equal value; as respects the
individuals of the parent generation, they are sometimes
of equal value with them, sometimes not.

4. If the secondary cells are not of equal value to
their parent-cells, a series of successive generations must
precede the last generation, the individuals of which are
again equivalent to the first mother-cell. The number of
these generations does not appear to be determinate.

Let us assume that a parent-cell (A) has produced a
number of secondary cells (8) which are of unequal value
to their parent. The individuals of this second genera-
tion propagate a third generation equivalent to their
parent-cells (B) or not equivalent (c.)

In the first case there may also be a fourth generation
(B”), a fifth (B’”), and more, which are all equal among
themselves, and to their parents, but not equal to the
parent-cell of the first generation (a); until at last a
generation is produced which is not equivalent to its own
parent. Now this is either equivalent (a’) to the first
generation, and the cycle closes with it, or it is still not
equivalent to it (x). In that case, it either propagates
again a number of equivalent generations, (c’. ©”. . .) or
non-equivalent (D, £...) until at last one appears, a’,
which is equivalent to the first generation, and thus the
cycle closes. By equivalent, the author means such indi-
viduals or generations as correspond with each other in
their essential, physiological, and organological relations,
although they may differ in unessential properties, such
as colour, size, internal consistence, &c. Non-equivalent,
are those generations which in their structure and vital
relations exhibit essential differences, such as “ still” and
“motile” cells, and among these, again, their various
forms; but particularly those which are derived from a
different mode of propagation.

PROTOCOCCUS PLUVIALIS. 543

There is a large number of different modes of propaga-
tion in Protococcus pluvialis, which, indeed, are all
fundamentally analogous, but produce very different forms.

The main distinction depends upon the number of
divisional individuals produced from a parent-cell. Their
number appears always to be a sub-multiple of 2. A
cell may produce 2, 4, 8, 16, 32, 64 individuals.

The propagation depends upon a division of the cell-
contents, particularly of the colourless or coloured pro-
toplasm, or of the primordial sac. ‘This body, without
any demonstrable influence of a nucleus, is capable of
subdividing into a determinate number of portions, in
the ratio just stated. Each of these portions acquires a
globular figure, in the next place surrounds itself with an
envelope of protoplasm, and then represents a visible
organism, which, after the resorption of the parent cell-
membrane, is capable of existence as an independent
reproductive individual.

‘he protoplasm which constitutes the external boun-
dary of’ this body, like all organised protoplasm, is
capable of secreting a rigid vegetable cell-membrane.
Two conditions now may present themselves.

1. Hither, such a rigid, ligneous membrane is formed
within the mother-cell, around the portions of proto-
plasm separated by division as above, that is the pri-
mordial sacs: in which case there are produced only
still secondary cells, usually different in their structure
from the pareut-cell. This process takes place only when
the parent-cell itself belongs to the still form, that is to
say, when the cell-contents or the primordial sac are closely
surrounded by a rigid, tough, ligneous membrane :

2. Or, the secondary individual, surrounded only by
a tunic of protoplasm, is liberated in this condition as a
primordial cell, and developes two vibratile filaments ;
it then has the faculty of motion, and represents a naked
zoospore. This process may take place as well in the
segmentation of still, as of motile primary cells. Here,
also, two conditions are possible.

544 THE NATURAL HISTORY OF

a. Either, the zoospore does not develop, during the
period of its motility, any rigid, tough, ligneous men-
brane, but only when the motility has ceased, whereupon
the zoospore passes into the still form. This is the case
in the peculiar naked zoospores, of minute size, which are
produced in greater number than 2, that is to say, to the
number of 8, 16, 32, 64, from the parent-cell. They
cannot multiply until they have assumed the still
form :

6. Or, the zoospore, during the period of its motility,
acquires a delicate but rigid membrane, which, however,
is separated from the primordial cell by an aqueous fluid ;
it then represents the encysted zoospore. These are
capable of propagation by segnientation, reproducing,
however, only motile forms, although sometimes non-
equivalent ones.

Besides this, the primordial cell in the encysted
zoospore may produce a second, rigid, tough, ligneous
membrane, around its whole periphery, by which it is
closely surrounded, whilst the delicate, outer enveloping
cell is removed. In this way the encysted zoospores pass
into the still form, and the cycle of possible developmental
forms is closed.

These appear to be the essential laws to which all the
phenomena attending the development of Protococcus
pluvialis may be referred; and the author then proceeds
to particular instances.

It is difficult, from the numerous uninterrupted links
of a chain of phenomena, to select that which should be
regarded as the representative of the normal condition,
and to which all the rest might be referred; but, on
the other hand, it is indifferent where the commence-
ment is made, and the author therefore commences with
the still form, which, within a rigid, tolerably thick,
ligneous membrane, indicated by a double contour
line, contains uniformly red, opaque, granular contents,
contractile in alcohol, and presenting in the centre
a cytoblast (?) in the form of a lighter coloured vesicle

PROTOCOCCUS PLUVIALIS. 545

(Fig. 2). This form arises from the metamorphosis of the
encysted zoospore into the still.

It may undergo changes, which may be distinguished
as essential and non-essential. ‘The latter have reference
to the change in form and colouring of the contents ; the
former, to propagation.

The latter process takes place by the division or seg-
mentation of the contents, at first as above stated, into
two, then into four, eight, or sixteen, when the division
usually terminates, and the segments pass into the motile
form ; although further st¢// generations may arise in the
same way. ‘The segmentation takes place in the follow-
ing mode. In the first place the cell becomes elongated,
so that its diameter in one direction is twice as great
as in the other (Fig. 5). Then a constriction of the
contents is perceptible about the middle of the length of
the cell, which gradually deepens, and the cell contents
or primordial sac are divided into two halves (Fig. 6).
These are separated by a line which forms between
them; and finally each is organised into a distinct
globule (Fig. 7), which becomes surrounded with a
ligneous membrane. The membrane of the parent-cell
is passive during this process—continuing, for a time,
to surround (sometimes in a gelatinous form) the secon-
dary cells; it is finally dissipated, and they thus become
free. The part played by the supposed cytoblast in the
process of segmentation is very doubtful.

During their dissolution, the cell-membrane of the de-
funct parent-cells is gradually converted into a mucoid
substance, retaining the secondary cells more or less in
connected masses. In this way arises the Prot. pluvialis,
leprosus, of Flotow. It is known also that other uni-
cellular Alge and Infusoria (Chlamidomonas, Euglena,
Monas, Vibrio, Zoospores, Diatomacez, &c.), under certain
circumstances, form similar. envelopes, either by the
secretion of a mucoid substance, or the transformation of
their cell-membrane into such.

After a certain number of such divisions, all in the

35

546 THE NATURAL HISTORY OF

still form—usually after the third or fourth—the ultimate
segments, instead of surrounding themselves with a lig-
neous membrane, become free, in the naked condition,
and developing the two motile filaments, represent a
motile primordial cell. (Fig. 12.)

The way in which the vibratile cilia are produced is
quite obscure.

The production of motile zoospores may take place on
the first segmentation of the contents of the primary, still
form, or after the intervention of an uncertain number of
such divisions as said before; but it is clear that the
segments of the contents of a still cell may at any time as-
sume the motile condition, and that their prolonged reten-
tion of the still form depends upon various external con-
ditions. But with division, on the other hand, it does not
appear possible for the still form to be changed into the
motile, whilst the contrary may undoubtedly take place.

The production of the enveloping cell around the
primordial cell is then described, as in a former part of
the paper; and the analogy between this process and
that of cell-formation, given by Mohl, Nägeli, Schleiden,
&c., pointed out. (Figs. 16, 17, 20, 21.)

The encysted zoospores, thus constituted, grow for a
time very considerably, and after a certain time exhibit
a tendency to propagate, that is to say to divide,

The contents of the primordial cell (which alone is
potential in this act) exhibit lines of division into four
symmetrical portions, most distinctly shown by the chlo-
rophyll vesicles. ‘Then, in directions corresponding to
these lines, the cell-contents are divided into four con-
tiguous portions, which gradually become isolated, and
assume a globular form, afterwards develope the two
vibratile cilia, and upon rupture of the parent-cell, be-
come free, and swim away. (Figs. 12, 13.)

A new enveloping cell is afterwards developed, and
these secondary motile cells become a second generation
of encysted spores, which, though in some respects unlike,
yet must be regarded as equivalent to their parent.

PROTOCOCCUS PLUVIALIS. 547

Sometimes the enveloping cell is developed around each
on primordial cell, whilst still within the parent-
cell.

After a certain number of generations of this kind,
their course is interrupted. A delicate double line is
perceptible around the primordial cell, which is the first
indication of the new, rigid, ligneous membrane, which
is formed around it (Fig. 46). The motile zoospore,
in other words, is again transformed into the still form.
The primordial cell is converted into a primordial sac,
and the cycle is closed.

Besides these, which are the most usual modes of pro-
pagation, viz. that of the s#Z cells into two, and of the
motile, into four secondary cells; there are a number of
others which may be considered as irregular, and in
which forms are produced, which do not re-enter the
usual cycle until they have gone through a series of
generations.

The cell-contents, for instance, of the still form, instead
of dividing first into two, and then these again each into
two secondary cells, and so on, may at once be sub-
divided into four segments, as takes place in the motile
form. (Fig. 8.)

More frequently and regularly, under certain circum-
stances, the cell-contents of the still form divide at once
into eight portions, which become naked zoospores of
small size (Figs. 31, 32). It is not quite clear what
becomes of this form of motile zoospore, but there
seems reason for believing that they occasionally develope
an enveloping cyst, and thus become encysted zoospores,
and occasionally secrete a cellulose tissue and become
still cells; but most of them probably perish without any
further change. They would thus correspond with the
smaller motile spores observed by Thuret and A. Braun
in other Alge (Hydrodictyon, Achlya, the Fucoidee, &c.)
associated with the larger germinating spores, and which
themselves were deprived of the germinative faculty.

In the same way that the “still” parent-cell may pro-

548 THE NATURAL HISTORY OF

duce, instead of two, eight secondary cells, so, on the
other hand, may the motile encysted zoospore, which nor-
mally produces four secondary cells, divide into only two.
(Figs. 22, 23, 35.)

It appears that both longitudinal and transverse divi-
sion of the primordial cell may take place; but that the
vibratile cilia of the parent-cell retain almost to the last
moment their function and their motion, after the pri-
mordial cell enclosed by it has long been detached as a
whole, and become transformed into the independent
secondary cells. (Fig. 38.)

The individuals of the secondary generation, when the
encysted parent-cell divides into two, are for the most
part equivalent to their parent; but should the latter
divide into more than two, its progeny then is very dis-
similar to it. For the encysted zoospores may also
divide into a generation of eight, sixteen, thirty-two,
according as the primordial cell has been partitioned
into eight, sixteen, or thirty-two portions, which become
organised into as many independent primordial cells.
The individuals of the secondary generation are of
course smaller, in proportion to the greater number of
parts into which the primordial parent-cell was sub-
divided, and they are also the more dissimilar to it in
proportion to the less quantity of its substance that they
may contain.

‘These minute zoospores, however they may originate,
are always true primordial cells, and, under unfavorable
circumstances, perish as such. What becomes of them
under other circumstances is not very easy to deter-
mine. It is certain, however, that they can pass into the
still form, assuming a globular shape, losing the vibratile
cilia, and secreting a ligneous membrane. They some-
times undergo this change while still within the parent-
cell. ‘They thus constitute a mulberry-like mass, which
gradually increases in size as the individual cells grow
(Fig. 40). They are also, after their liberation from
the mother-cell, sometimes seen to form an enveloping

“PROTOCOCCUS PLUVIALIS. 549

cell around them, thus becoming encysted zoospores,
differing from the larger form of that kind only in size
(Fig. 41).

The author once observed four cells arranged as it
were in a cross, and connected to each. other by the
anterior end (Fig. 25), and which, from their struc-
ture, appeared to be referable to the encysted motile
zoospore. It is a very remarkable circumstance, and one
difficult of explanation, that in this case each of the four
larger primordial cells was connected with each of the
two contiguous cells by two transverse processes, which
passed through the enveloping cell-membrane. In this
respect there was a resemblance to Chlamidomonas pul-
visculus and Trachelomonas volvocina, Morren, which re-
main connected by the beak or vibratile cilia. (‘ Recherch.
sur la Rubefact.,’ Tab. II, fig. ii 4, Tab. V, figs. 9, 8.)
I think, however, that this condition is to be explained
upon the supposition that four primordial cells have been
formed within a parent cell by the usual mode of seg-
mentation, but that instead of their being completely sepa-
rated from each other, they remain connected, and that
then, after resorption of their common, parent enveloping-
cell, also develope in the usual way special enveloping-cells,
which are of course in contact in the centre, and necessa-
rily assume a cruciate figure. A smaller portion, which
in the organisation of the segments was not taken into
any of them, has become an independent but more
minute primordial cell, lying between the arms of two of
the primordial cells constituting the cross. The above
process seems to be analogous to what takes place in
Gonium or Volvox, in which the individual segments,
after division, are retained in connexion.

Having thus gone over the various morphological and
developmental conditions of the Protococcus, the author
proceeds to its biology.

The most striking of the vital phenomena presented
by this organism is that of periodicity. Certain forms,
for instance encysted zoospores, or certain colours, ap-

550 THE NATURAL HISTORY OF

pear in a given infusion, at first exclusively, then princi-
pally; they gradually diminish, become more and more
rare, and finally disappear altogether. After some time
their number again increases, and reaches, as before, an
incredible amount; and this proceeding may be repeated
several times. Thus a glass which at one time pre-
sented only still forms, contained some weeks before
nothing but motile ones, and would again in a few weeks
contain nothing else.

The same thing may be observed with respect to the
segmentation. Ifa number of motile cells are transferred
from a larger glass into a small capsule, it will be found,
after the lapse of a few hours, that most of them have
subsided to the bottom, and in the course of the day,
they will all be observed to be on the point of sub-
division. On the following morning the divisional gene-
ration will have become free ; and on the next, the bottom
of the vesse] will be found covered with a new generation
of self-dividing cells, which again proceed to the forma-
tion of a new generation, and so on. This regularity,
however, is not always observed.

The influence of every change in the external conditions
of life, upon the propagation, is highly remarkable. It
is only necessary to pour water, from a smaller into a
larger, shallower vessel, or one of a different kind, at
once to induce the commencement of segmentation in
numerous cells. The same thing occurs in other Alge ;
thus the Faucherie almost always develope zoospores,
at whatever time of year they may be brought from their
natural habitat into a room.

Light is conducive to the manifestation of vital action
in the motile zoospores, and they always seek after it,
collecting themselves at the surface of the water, and at
the edges of the vessel.

But, in the propagative act, on the contrary, and
when they are about to pass into the still condition, the
motile Profococeus-cells seem to shun the light; at all
events they then seek the bottom of the vessel, or that

PROTOCOCCUS PLUVIALIS. 551

part of the drop of water in which they may be placed,
furthest from the light.

Too strong sunlight, as when it is concentrated by a
lens, at once kills the zoospores. A temperature of
undue elevation is injurious to the development of the
more active vital activity, that is to say, for the formation
of the zoospores ; whilst a more moderate warmth, parti-
cularly that of the vernal sun, is extraordinarily favor-
able to it. Frost destroys the motile, but not the still
zoospores.

When kept in the dark, the zoospores become blanched,
that is to say they acquire a pale green colour, almost
without granules or red substance; the chlorophyll-
vesicles, moreover, are not visible, so that the contents
of the primordial cell appear as a soft, homogeneous,
substance. The membrane is of a soft gelatinous con-
sistence ; the motile zoospores continue their movement
uninterruptedly, without, as is usual, sinking to the
bottom, or passing into the still form, or into the stage of
segmentation.

Under the influence of light, the cells give out a large
quantity of oxygen. It is perhaps the continued greater
evolution of gas by the motile spores, as compared with
those in the still condition, that causes them by pre-
ference to rise to the surface, and the latter to sink.

Strychnine and morphine, even in the proportion of
1 part to 150 parts of water, had no immediate influence
on the motion and life of the cells, whilst a solution
of iodine so weak as not to render starch anywhere
visible, acts at once as an active poison. Cohn observed
that when he had starch granules together with motile
zoospores on the object glass, and added a very dilute
solution of iodine, the motile cells, by their death, shew
themselves to be much more sensitive reagents with
respect to iodine, even than starch. Rapid evapora-
tion of the water in which the motile forms of Proto-
coccus may be contained, kills them at once, but a more
gradual, such as takes’ place in deep glasses, causes

552 THE NATURAL HISTORY OF

them merely to pass into the still form, in which they
retain their vitality for years.

Cohn observed very frequently that the contact of
metal with the water in which the Protococcus-cells were,
was destructive to their life.

In the still form, the phenomena attendant upon the
cessation of life, are somewhat different from those in
the motile cells. In certain circumstances, the con-
tents, particularly in the red zoospores, dissolve, from
the periphery, into innumerable minute droplets. Or a
peculiar dissolution of the coloured contents takes place,
in such a way that they lose their colour, also from without
to within, so that at last the cell appears dense and
opaque, but altogether colourless, and is deprived of all
vitality. (Fig. 43.)

The paper then concludes with some general consider-
ations.

1. The question arises, whether the Protococeus is
necessarily to be regarded in all its stages of development
as a Plant; or whether it should not rather be referred
to the Animal kingdom.

To any one who reads the writings of the most distin-
guished observers on this subject, it appears almost in-
comprehensible, that any doubt could exist whether any
organism, when sufficiently investigated, should be an
animal or aplant. For all, nearly without an exception,
agree in this, that an animal and a plant are essentially
and typically of distinct structure, and that this essential
diversity must also be expressed m the most minute
and lowest organisms; and that, therefore, there can be
no question of any real analogy between an animal and
a plant, to say nothing ofa relationship or a transition
from one into the other.

It appears, however, to Cohn, that the question of
animal or plant has been stated too generally, and
requires to be defined with greater precision. As the
question is generally put, it would include the mquiry

PROTOCOCCUS PLUVIALIS. 553

as to whether the Protococcus pluvialis were allied to the
Lion or to the Oak. All our common notions of the
two kingdoms being derived from such higher organisms
as those, and not from those of the invisible world.

But the Pro/ococcus is as far from the Lion as it is from
the Oak; there are observable in it, properties which would
appear to find their analogies only in certain animals or
certain plants, viz., among the Infusoria or the Algze.

Of the /atier, again, the more highly organised, multi- '
cellular forms must be excluded, these belonging mani-
festly to the Vegetable Kingdom. A Fucus, for stance,
is incontestably differently constructed from a Protococcus
cell. It is only the so-called unicellular Algee of Nägeli,
the Palmellee and Diatomacex, about whose proper
position there can exist any possible doubt.

In the same way, of Infusoria, next to the Rotifera, all
those among the Polygastrica of Ehr. must be excluded,
which have distinctly a mouth and anus, as well as an
intestinal canal, or at least an cesophagus. With respect
to these, also, no doubt can arise as to their proper
position in the scale of animated nature.

Besides these, however, there are Infusoria, having
neither intestine nor anus, which do not take in any solid
nutriment, and in which the existence of a mouth is not
demonstrable by direct observation, and can only be sur-
mised from analogy. These constitute the division of the
Anentera, Ehr., Astoma, v. Siebold. With respect to
these, it may certainly be reasonably questioned, whether
an organism should be more properly referred to this
division of the Infusoria, or to the Algze just mentioned.
It cannot but be doubtful whether a given creature is to
be regarded as belonging to the Monadina, Cryptomo-
nadina, Volvocina, Astasiee, Bacillarıe, Ameba, Arcel-
ling, &c., or whether it should not be referred to the
Cryptococcacee, Protococcacee, Palmellex, Desmidiee,
and Diatomacee. It may even be questioned, whether
some of these natural families be not more nearly related
with some families in the other kingdom, than with their

554 THE NATURAL HISTORY OF

neighbours in the kingdom to which they themselves
belong, or whether even certain divisions from both natural
kingdoms might not properly be associated. It is only
with this limitation that the question, as here considered,
must be understood,— whether Protococcus pluvialis is to
be regarded as animal or plant; or, since of the above-
mentioned genera of Infusoria some only present any
similarity with it, whether it is to be considered as an
‘animal belonging to the Monadina, Cryptomonadina,
Volvocina, or Euglene, or whether it should not be
referred, as an Alga, to the family of the Palmellez.

Although Flotow, after much consideration, comes to
the conclusion that Protococcus pluvialis must be regarded
as a plant, the reasons upon which he is induced to come
to this conclusion do not appear to be well chosen. They
are,—1. its capability of revival after having been dried
for months and years; 2. the viability of separate por-
tions of its substance; 3. the occurrence of gemmation
which, moreover, in the proper sense of the word, is more
than doubtful. All of which circumstances may be
observed occasionally in the Animal Kingdom.

By Morren, on the other hand, this organism, under
the name of Discenea purpurea, is arranged among the
Infusoria in the family of the Cryptomonadina, Ehr., and
has assigned to it a place close to Zrachelomonas zone,
Morren, (non Ehr.) Focke also conceives that the reasons
above assigned by Flotow for the vegetable nature of
Protococcus, are the rather calculated to prove its animal
nature.

According to Ehrenberg, for an organism to be charac-
terised distinctly as an Infusorium, it is requisite that it
should possess a complete organisation analogous in all
respects to that of the higher animals ; on the other hand,
however, Dujardin, Siebold, Kölliker, &c., contest this,
considering spontaneity and contractility alone, as indis-
pensable criteria.

Now to consider Protococcus pluvialis in both these
points of view.

PROTOCOCCUS PLUVIALIS. 555

First, as regards Ehrenberg’s doctrine. The organisa-
tion of Protococcus may very plausibly be referred to that
of the anenterate Infusoria, as understood by that ob-
server ; in this case the enveloping cell might perhaps be
explained as the shield ; the primordial cell as the proper
body of the animal; the chlorophyll-vesicles, colourless
granules, and cytoblasts, as the testes ; the red and green
globules as ova; the frequently existing red pigment spots
as eyes; the vibratile cilia as a proboscis; the hyaline
spot as mouth; and the vacuoles as stomachs. At all
events the organs which Ehrenberg has figured and
described as of such nature in Zrachelomonas, Volvoz,
Euglena, Chlamidomonas, Closterium, Euastrum, &c.,
present such appearances that, although they are in reality
organised in an essentially different way, they cannot be
optically distinguished from what they are represented
to be.

On the other side, these bodies correspond in all
respects with the organisms which are found either
absolutely in indubitable plants, or in the spores of such
plants.

Whence it is apparent that the proof of an animal
organisation offered by Ehrenberg, does not suffice in
doubtful cases incontestably to prove the animal nature
of a doubtful creature when alive, because formations are
presented even in plants which cannot be directly shown
to be distinct by optical or chemical means, but only
indirectly, with the aid of analogy.

If, on the contrary, that view of the structure of the
Infusoria be the more correct, which regards them only
as simple contractile cells, and all the above elementary
parts as parallel, not with animal but with vegetable
organisms, we arrive at more comprehensive conclusions.

One of the characteristics of Protococcus is this, that it
affords analogies, at different periods of its growth, not
with one only, but with many genera hitherto considered
distinct. Thus the motile, or “swarming,” form agrees
with the genus Pandorina, Ehr., or more closely still

556 THE NATURAL HISTORY OF

with Chlamidomonas, from which, indeed, it is scarcely to
be distinguished. But the latter, according to Cohn, has
not yet been observed in the “ still” condition.

But Pandorina and Chlamidomonas have \ong enjoyed
only a very doubtful character as animals; Kützing having
arranged the former among the Palmellaceze, as Lotryo-
cystis morum ; and Siebold the latter among the Algz,
in spite of the only certain character admitted by him as
distinctive of an animal nature, viz., the contractility of
the body.

Protococcus pluvialis, however, presents the most
striking analogies with genera in which this property is
exhibited in the highest degree, the genera Zuglena and
Astasia, which, according to our present knowledge,
must be regarded as indubitable animals, their claim to
be so considered having even never yet been called in
question by any careful observer.*

Among the points in which the closest resemblance
exists between Protococcus and Huglena, may be enu-
merated the following :—

1. The red matter in the latter presents precisely the
same characters, and, like that of Protococcus, is coloured
blue by iodine, and contains corpuscles not to be distin-
guished from the chlorophyll-vesicles.

2. The colourless extremities of Euglena manifestly
correspond with the colourless elongation of protoplasma
at the two ends of the Protococcus cell; the beak also of
Euglena, with its single cilium, precisely corresponds
with the biciliated extremity of Protococcus.

3. The eye-spot of Zuylena appears to be chemically
analogous with the red pigment spot in certain stages of
the zoospores of Protococcus ; it is equally coloured blue
by iodine.

If to the above it be added that Zuglena, at least
according to Dujardin, Siebold, and Kolliker, equally
presents the characters of a simple closed cell, it will be

* This is now, by no means, the case.—[Ep. ]

PROTOCOCCUS PLUVIALIS. 557

apparent that the motile form of Euglena is constituted
on the same type as the primordial cell of the motile form
of Protococeus.

The author then details some observations on the
development of Zuglena viridis.

Huglena is not always motile ; at certain times it passes
into a state of rest. ‘To this end, it assumes a globular
form, developes more opaque, denser contents, and forms
around itself, a rigid, colourless membrane ; in this state
it cannot be distinguished from the still form of Proto-
coccus pluvialis, and as in that plant, the cells are often
united into floating expansions. In this form, and par-
ticularly when aggregated into these expansions, it has
already been occasionally placed among the Algz ; Micro-
cystis Noltii, Kg. appears to be the still form of Zuglena
sanguinea, and M. olivacea, Kg. is probably to be referred
to Euglena viridis.

This stage, however, of the so-called process of
becoming encysted, is not, as commonly supposed,
connected with the decease of the organism, but within
the membrane, segmentation goes on; the coloured,
enclosed globular body subdividing exactly as in Proto-
coccus into two, four, eight, sixteen, thirty-two, or more
portions. ‘These isolated, primordial cells, as they may be
called, become free, by rupture of the rigid wall enclosing
them; and either resemble their parent, or when much
smaller, are very dissimilar to it, assuming more the ap-
pearance of green, eyeless Monads.

On the other hand, the motile form of Euglena, also,
just like the motile zoospore of Protococcus may sub-
divide into two, or it may be into more, also motile
secondary individuals. Whence it is manifest that the
development of Zuglena viridis, proceeds on precisely
the same type as that of Protococcus pluvialis.

With respect to the motion of the Protococcus cells ;
it is to be noticed that Ehrenberg, and with him all
later observers, agree that animal motion is voluntary,
arising from internal psychical causes, that it is conscious

558 THE NATURAL HISTORY OF

and directed to some object ; whilst that of plants would
appear to depend upon external physical causes or stimuli ;
that it is not voluntary, nor directed to any object,
but automatic (vide Ehr., Abh. d. Berl. Ak. 1830).
Cohn, however, from numerous observations expressly
directed to this point, is disposed to call in question, the
existence of this essential distinction between the motions
of the Infusoria, and that of the vegetable zoospore.

Leaving out of the question the more highly organised
Infusoria furnished with the manifest mouth and ceso-
phagus, the motion of a large part of the Anentera, Ehr.
Astoma, Siebold, is not essentially different from that
of the zoospores of certain Algze.

Towards the end of the paper, Cohn observes, that in
the course of its preparation he had only been able upon
optical and physiological grounds, to render it probable,
that the rigid cell membrane of the still form and the
tender enveloping cell of the motile zoospores, consist
of the same non-nitrogenous material, of which the
rigid membrane of all plant-cells is composed—viz. :
cellulose ; he had, however, since succeeded, by chemical
means, in placing this fact beyond doubt. If a drop of
water containing some still and motile zoospores, be
brought in contact simultaneously with a very dilute
watery solution of iodine, and moderately diluted sul-
phuric acid, the “enveloping” cells of the motile and
the cell-membrane of the still form, immediately assume
a beautiful blue colour (Fig. 47). In performing this
experiment, it is necessary to employ neither a too con-
centrated, nor a too much diluted sulphuric acid.

The author concludes by some general observations on
the subject of the “Alternation of Generations,” exhibited
in such instances as Profococcus pluvialis, and on the im-
portance of the history of its development, with relation to
a systematic arrangement of the Alge. Most of our spe-
cies and genera, are based merely upon differences in size,
form, and thickness of the cell-wall, and the colour, con-
sistence, and intimate organisation of the contents. But

PROTOCOCCUS PLUVIALIS. 559

the history of the development of Protococcus pluvialis,
shews how very uncertain such characters are. It cannot
be doubted, moreover, that the great diversities exhibited
in the above respects, at different stages of its growth, by
Protococcus pluvialis, exist also in other Alge, if they
were duly sought after, and that researches in other
species, from the same points of view as those embraced
in the present memoir, would probably reduce very
materially the large number of genera and species of
Alex.
. Thus we see that a single species, owing to its nu-
merous modes of propagation, can pass through a number
of very various forms of development, which have been
either erroneously arranged as distinct genera, or at
least as remaining stationary in those genera, although,
in fact, only transitionary stages. Thus the still Proto-
coccus cell, (Fig. 2,) corresponds to the common Proto-
coccus coccoma, Kg. When the border becomes gelatinous,
it resembles P. pulcher (Fig. 70); and the small cells,
P. minor. The encysted motile zoospore is the genus
G'yges granulum among the Infusoria, resembling also, on
the other side, P. turgides, Kg. and perhaps, P. versa-
tilis, Braun. 'The zoospores divided into two (Figs. 23,30),
must be regarded as a form of Gyges bipartitus, or of
P. dimidiatus. In the quadripartite zoospores, with the
secondary cells arranged in one plane, we have a Goniwm
(Fig. 37). That with eight segments (Fig. 38,) corre-
sponds to Pandorina Morum, and that with sixteen, to
Botryocystis Volvow (Fig. 44). When the zoospore is
divided into thirty-two segments, it is a Uvella or Syn-
erypta (Fig. 40). When this form enters the “still”
stage, it may be regarded as a form analogous to
Microhaloa protogenita; this Algal genus is probably,
speaking generally, only the product of the Uvella division
in the Zuglene or other green forms. The naked
zoospores (Fig. 32), finally, would represent the form
of a Monad, or of an Astasia ; the caudate variety, ap-
proaches that of a Bodo.

560 PROTOCOCCUS PLUVIALIS.

A critical and comparative consideration of the fore-
going facts would therefore appear to render untenable
almost all the principles which modern systematists
have hitherto adopted as the basis for the construction
of their Natural Kingdoms, Families, Genera, and
Species.

But it must not hence be concluded, that the result
of these investigations implies the existence of a state of
complete anarchy in the domain of microscopic organisms ;
or that any one form among them, may assume any
other form indifferently; that, in fact, there are no real
species in the invisible world. Such is by no means ~
the case.

Critical enquiries such as the present, have for their
result—like the spear of Telephus—the healing of the
wound they inflict. It is manifestly better,—although at
the expense of erroneous notions, long admitted as in-
fallible—to substitute, by the aid of a complete and
continuous history of development, a much more defined,
because natural idea, of Genus and Species, for that
hitherto set up, in artificial, but, at the same time, un-
natural Systems.

Tukfen West Gren Lath = . Berd &: Wee

Chromo | sup

DESCRIPTION OF FIGURES.

Fig.

1.—A small “still” cell of Protococcus pluvialis,
revived after desiccation. The contents gru-
mous, almost filling the cell-membrane.

2.—A very large cell, in which the red, finely granular
contents, fill up the membrane, and have in the
centre a clearer space. (cytoblast ?)

3.—A green cell with chlorophyll-vesicles, containing
an excentric, reddish, lighter-coloured vesicle
(nucleus ?) surrounded by an opaque red ring.

4.—A cell which had been dry for six years, under-
going segmentation after its revival; one half is
green and granular ; the other red, presenting an
oil-like substance.

5.—A cell which has assumed an elliptical figure pre-
paratory to its dividing.

6.—Division further advanced.

7.—Completed division. The secondary cells appear
to have a cellulose coat, and are surrounded by
the mother-cell, which has become gelatinous.

8.—Division into four.

9.—The same, still surrounded by the parent-cell.

10.—-Commencement of division; a green, small cell,
with a red zone at the border, and red central
substance, as well as a lighter coloured nucleus.

11.—A “still” cell, containing, within a distant, dense,
colourless coat, a coloured globule also surrounded
with a membrane.

12.—A large naked zoospore, green, with red central
substance, and a colourless spot at the anterior
end, with two vibratile cilia, originating, either in
the division of an encysted zoospore or from a
“still” cell.

13.—An irregular-shaped, quadrangular, flat, Zuglena-
like zoospore, with chlorophyll-vesicles, colourless
anterior end, and two cilia.

36

562 DESCRIPTION OF FIGURES.

Fig.

ook green cell with red central substance, on the
point of assuming the motile form.

15.—An encysted zoospore, with filaments of proto-
plasm, (P. setiger, Flotow), a distant ‘ envelop-
ing cell,” two cilia, chlorophyll-vesicles, &.

16.—An encysted zoospore, with distant “ enveloping
cell,” green, gelatinous, primordial cell; red,
granular, disseminated central substance, and a
colourless point, (P. papillatus, Flot.)

17.—A very small, globular, encysted zoospore, (P. ro-
tundatus, Flotow.)

18.—An encysted zoospore, pointed at both ends, alto-
gether green, (P. rostellatus, Flot.)

19.—Commencing division of the primordial cell into two.

20.—A young pyriform primordial cell, around which
the “enveloping cell” is just beginning to show
itself distinct from the primordial cell.

21.—An older cell, with colourless vacuoles.

22.—Commencing division into two; the wholly green,
primordial cell, closely surrounded by-the en-
veloping cell, shows a constriction in the middle.

23.—Comimencing division into two; each secondary
primordial cell has developed an enveloping cell
around itself, whilst still within the parent cell.

24.—Commencing division into four.

25.—An unusual and incomplete division into five;
four pointed, encysted zoospores, not completely
parted after the resorption of the common “ en-
velopmg cell,” remaining connected by pro-
cesses arising from the point where the cilia are
placed; a smaller portion has become organized
into a naked primordial cell, also connected with
the others. (Vide fig. 39.)

26.—Only half of the primordial cell consists of the
green globular substance; the other half is a
colourless granular protoplasm, enclosing in the
centre a red substance resembling a nucleus.

27.—An encysted zoospore in the commencement of

DESCRIPTION OF FIGURES. 563

Fig.

: deliquescence. The primordial cell is resolved
into green and red granules, forms clear vacuoles,
and is on the point of filling up the enveloping cell.

28.—An encysted zoospore which has deliquesced ; the
primordial cell has entirely filled the “ enveloping
cell,” and become resolved into green and red
granules.

29.—An encysted zoospore, which has passed into the
“still” condition; the spherical, wholly green,
primordial cell, has acquired a closely investing
cellulose coat, whilst the ‘enveloping cell,” has
become resolved into a mucoid substance, on
which the cilia are no longer visible.

30.—Division of a “ still” cell into two elliptical secondary
cells, which present a nucleus in the centre, and
remain enclosed by the parent cell, become gela-
tinous. (Vide fig. 7.)

31.—Division of a “ still” cell into eight : the parent cell
is resolved into a gelatinous substance, and
encloses eight small, cylindrical, red zoospores.

32.—Two of these zoospores after their escape.

33.—Yellow-green “still” cell, with gelatinous envelope.

34.—An encysted zoospore, the primordial cell of which
is on the point of divisioninto two. The remote,
enveloping cell supports the two cilia, whose
presence is only indicated by the current they
produce.

35.—An elliptical encysted zoospore, the primordial cell
of which is already divided into two secondary
cells. The vibratile cilia and transparent pro-
jections upon which they are placed, are visible
within the parent-cell.

36.—One of the secondary cells after its liberation.

37.—Division of an encysted cell into four; the globular,
green, granular, secondary cells, almost fill the
parent-cell; arranged something like the cells in
Gonium pectorale.

38.—Division of an encysted zoospore into eight globular,

564 DESCRIPTION OF FIGURES.

Fig.
secondary, primordial cells, which almost fill the
parent-cell. Their disposition resembles that of
Botryocystis morum, Kg.

39.—Incomplete division of an encysted zoospore into
four, also encysted secondary cells, which remain
connected in the centre after the removal of their
common enveloping cell. This seems to repre-
sent a further development of that given in
figure 25.

40.—Division of an encysted cell into thirty-two minute,
spherical, entirely green, primordial cells, which
completely fill their delicate parent-cell. This
arrangement corresponds to the genus Spheras-
trum tesserale, Kg., or to Uvella virescens, Ehr.,
or to Synerypta volvox, Ehr.

41.—Zoospores from the last-described form escaped
from the parent-cell. One of them (a) shows
the formation of a membrane around it.

42.—An encysted zoospore with a spherical primordial
cell, the green, non-granular contents of which,
are retracted to one side, in a crescentic form,
whilst a colourless vesicle occupies the other half.
This modification appears to depend upon a
deficient supply of water.

43.—A red cell, which, by desiccation, has become
colourless, showing grumous contents with oil-
globules.

44,—A large red “still” cell, the contents of which are
divided into numerous (64 ?) segments.

45.—A red encysted cell.

46.—A red “still” cell, originating in the transition of
the cell represented in fig. 45 into the “ still”
condition.

47.—An encysted zoospore, treated with iodine and
sulphuric acid.

*,* All the figures are magnified under a power of
500 linear.

INDEX OF GENERA OF MICROSCOPIC ALGA
TREATED IN THIS VOLUME.

Achnanthes, 407.
Achnanthidium, 407,
Actiniscus, 487.
Actinocyclus, 477.
Actinoptychus, 478.
Amphipentas, 481.
Amphipleura, 421.
Amphiprora, 422.
Amphitetras, 480.
Amphora, 423.
Anabaina, 146.
Aphanochete, 184, 209, 230, 233,
250

Apiocystis, 133, 209.

Arthrosiphon, 178.

Ascidium, 125, 127, 185, 186, 200,
209, 267, 286.

Bacillaria, 399.

Bambusina, 291, 295.

Batrachospermum, 150, 151,

Berkeleya, 426.

Biddulphia, 484, 512.

Botrydium, 128, 193, 220, 274.

Botryocystis, 159, 209, 559.

Bryopsis, 129, 140, 166, 268.

Bulbochete, 141, 151, 156, 157, 183,
201, 209, 303.

Campylodiscus, 394.

Caulerpa, 129, 174.

Ceratoneis, 421.

Chetomorpha, 185, 186, 268

Chetophora, 139, 151, 156, 183,
208, 224, 231, 253.

Chantransia, 143, 151, 183, 231.

Characium, 125, 185, 209, 229, 230,
250.

Chlamidococeus, 188, 158, 174, 184,
196, 205, 211, 216, 224, 229, 238,
250, 258, 498, 518.

Chlamidomonas, 214, 215, 216.

Chlorococcum, 213, 260, 508.

Chroococcacee, 131, 174, 190, 197.

Chroococcus, 131, 182, 230.

Cladophora, 150, 174, 185, 199,
= 235, 236, 239, 240, 253,
268.

Climacosphenia, 465, 512.

Closterium, 133, 140, 175, 204, 281,
289, 291, 292, 259, 497.

Cocconeis, 405.

Coceonema, 286, 410.

Coleochete, 141, 151,183, 208, 253,
270, 298.

Conferva, 184, 205, 209.

Coscinodiscus, 476.

Cosmarium v. Euastrum.

Cyclotella, 385.

Cylindrocystis, 287.

Cylindrospermum, 146.

Cymatonema, 141.

Cymbella, 409.

Cymbosira, 408.

Cystococcus, 125, 185.

Cystoseira, 248.

Denticula, 379.

Desmidium, 294.

Desmidiacex, 133, 139, 174, 203,
247, 283, 290, 497.

Diadesmis, 424.

Diatoma, 382.

Diatomace®, 132, 139, 190, 247,
283, 345.

Dictyocha, 488.

Dictyospherium, 132, 209, 238.

Didymoprium, 291, 295.

Docidium, 180, 291.

Doryphora, 406.

Drapamaldia, 139, 151, 156, 183,
208, 224, 231.

Dysphinctium, 203.

566

Echinaria, 400.
Encyonema, 411.
Endococeus, 213, 268.
Enteromorpha, 184, 250.
Epithemia, 374.
Euactis, 147, 178.
Euastrum, 133, 181, 224, 294, 295,
300.
Eumeridion, 378.
Eunotia, 286, 375.
Exococcus, 254.

Fragillaria, 381.
Frustulia, 425.

Gallionella, 389.

Gl&ocapsa, 131, 132, 182, 190, 499.
Gleococcus, 159, 209.
Gleocystis, 131, 161, 182, 190.
Gleodictyon, 498.
Gomphonema, 238, 286, 412.
Gongrosira, 183, 209.

Gonium, 159.

Grallatoria, 402.
Grammatonema, 381.
Grammatophora, 473.

Gyges, 499, 559.

Hematococcus v. 498, 508, 518, also
v. Chlamidomonas.

Haplosiphon, 150.

Hassallia, 150.

Himantidium, 286, 376.

Homeeocladia, 426.

Hormidium, 131, 208.

Hyalosira, 466.

Hyalotheca, 291, 295.

Hydrodictyon, 125, 127, 137, 156,
171, 185, 186, 190, 197, 199,
208, 219, 220, 261.

Isthmia, 482.
Isthmosira, 291, 295.

Lemania, 154.
Leptomitus lacteus, 270.
Licmophora, 464.
Lithodesmium, 480.
Lysigonium, 389.

Mastichonema, 147, 187.
Mastichothrix, 147.
Melosira, 139, 299, 389.

INDEX.

Meridion, 377.

Mesocarpus, 135, 288, 289, 369.
Mesogena, 488.

Micromega, 437.

Microhaloa, 559.

Monnema, 430.

Mougeotia, 288.

Navicula, 413.
Nostoc, 145, 155.

Odontella, 483.

Odontidium, 380.

@dogonium, 141, 148, 150, 156,
157, 161, 162, 163, 164, 170, 175,
183, 196, 201, 212, 224, 227,
231, 247, 281, 300, 301, 302.

Ophiocytium, 260.

Oscillaria, 132, 197.

Palmellacee, 131, 174, 190, 213,
499,

Palmoglea, 133, 135, 202, 285.

Pandorina, 159, 209, 212, 224, 499,
559.

Pediastrum, 125, 161, 184, 200,
209, 250, 266.

Penium, 181, 190, 203, 289, 292.

Pleurococcus, 131, 182, 213, 230,
258.

Pleurodesmium, 495.

Pododiscus, 387.

Podosira, 388.

Podosphenia, 462.

Prasiola, 131.

Protococcus, 125, 127, 209, 212,
218, 258, 499, 507, 518.

Pyxidicula, 387.

Raphidoglea, 426.
Rhabdonema, 4:67.
Rhipidiphora, 4.63.
Rhynconema, 289.

Rimaria, 402.

Rivularia, 146, 147, 148, 178.

Saprolegnia, 185, 188, 252, 268, 269,
298.

Sarcococca, 36.
Scaplıularia, 399.
Scenedesmus, 250.
Schizochlamys, 181.
Schizonema, 139, 286, 428.

INDEX.

Schizosiphon, 147, 178.

Sciadium, 187, 209, 260.

Seytonema, 146, 147, 178, 186.

Sirogonium, 288.

Spermosira, 146.

Spheeroplea, 164, 271, 281.

Spherozyga, 146.

Sphenella, 411.

Sphenosira, 413.

Spirogyra, 135, 175, 180, 196, 201,
224, 239, 241, 244, 281, 289, 300.

Staurocarpus, 134, 281, 296.

Stauroceras, 287.

Stauroneis, 422.

Staurospermum, v. Staurocarpus.

Stigeoclonium, 139, 156, 163, 183,
208, 224, 360, 498.

Striatella, 466.

Surirella, 396.

Syncyclia, 410.

Synedra, 399.

Tabellaria, 470.
Tabularia, 402.
Terpsinoe, 472, 512.
Tessella, 466.

567

Tetmemorus, 291.
Tetrachococcus, 258.
Tetracyclus, 469.
Tetraspora, 132, 209.
Tolpothrix, 147, 186.
Triceratium, 487.
Tripodiscus, 482.

Ulothrix, 125, 148, 156, 159, 175,
184, 200, 208, 228, 250, 360,
498.

Ulnaria, 400.

Ulva, 125, 184, 250.

Urococcus, 178, 230.

Vaucheria, 128, 140, 157, 163, 174,
183, 209, 212, 221, 251, 296.
Volvocinex, 158, 159, 208, 216,

250.

Zygnema, 175, 288.

Zygnemacee, 133, 135, 164, 174,
180, 287, 359.

Zygogonium, 177, 288.

Zygoceras, 486.

©. AND J. ADLAND, PHINTEKS, BARTHOLOMEW CLOSE,

REPORT

OF THE

COUNCIL OF THE RAY SOCIETY,

Read at the Tenth Anniversary Meeting, held at Hvıı, Sept. 12¢h, 1853;

W. SPENCE, Esa., F.R.S., ın THE CHAIR.

Tue Ray Society was established in the year 1844, for the purpose of publishing -
and supplying to its Members, original works, translations, and reprints of works,
that were not likely, on account of their expense, to be published in the transactions
of existing societies, or to be undertaken by publishers, in consequence of the im-

‘probability of their meeting with a remunerative sale. The Council of the Ray
Society feel it necessary to remind the Members of this fact, as it will explain, on
the one hand, why their works cannot be of ahighly popular character, and on
the other hand, why they feel that they have a claim on the support of all those
who are anxious to promote the study of Natural History Science. As to how
the Society has fulfilled its mission, they would appeal to the twenty-two volumes
which have already been issued to the Members. Many of them are standard works
on the subjects to which they have been devoted, and all have contributed to
advance a knowledge of the principles and facts involved in the study of the sciences
of Zoology and Botany.

Since the last Anniversary Meeting of the Society, which was held at Belfast, in
September, 1852, the following works have been distributed to the Members:

1. Vol. I of Mr. C. Darwin’s Monograph of the family of Cirripedes; including
the Sea-acorns (Balani).

2. Vol. III of the Bibliographia Zoologie et Geologiz, by Professor Agassiz ;
edited by H. E. Strickland, Esq., F.R.S.

The Council had hoped that they should have been able to have announced at the
present Meeting the distribution of two other works, but circumstances over which
they have had no control have prevented their being able to do so. One of these
works, the sixth and last part of Messrs. Alder and Hancock’s work on the Nudi-
branchiate Mollusca, has been deferred on account of the wish of the authors to use

2 REPORT OF THE RAY SOCIETY.

all the materials in their possession up to the present time, and thus to render the
work as complete as possible.

The publication of the second volume of Mr. Darwin’s work on the Cirripedes has
also been delayed, in order to enable the author to include in it his researches upon
collections of animals belonging to this family which have been recently made.

Instead of a mixed volume of papers by foreign authors on subjects in Zoology
and Botany, the Couneil have resolved, at the request of many of their botanical
Members, to publish a translation of Dr. A. Braun’s work on the Rejuvenescence of
Plants. This work will be edited by Mr. Henfrey; and Meneghini’s paper on the
Animal Nature of the Diatomacee, and an abstract of Cohn’s paper on the Natural
History of Protococcus pluvialis, will be added. This book is nearly completed, and
will be speedily issued, with the sixth part of Messrs. Alder and Hancock’s Mono-
graph. The publication of Hoffmeister’s work on the Reproduction of the
Cryptogamia, which the Council had thought of translating, they are glad to state
has been undertaken by Mr. Highley, and they hope will shortly appear, so as to be
accessible to the English student. °

For the year 1854, the Council propose, if no unforeseen circumstance arise, to
publish the fourth volume of the Bibliography of Zoology and Geology. They have
also great pleasure in announcing that they have received the plates of Professor
Allman’s work on the British Fresh-water Zoophytes, and that this work, with
thirteen coloured plates, in imperial 4to, will be one of the publications for 1854.

The Council would especially call the attention of the Members to their financial
condition. Last year they had to report that £657 were due on that and the
past years. They have now to report that £707 are due. Of this sum:

£336 18s. is due for 1853,

£144 138 „ » 1852,
£91 6s. „ » 1851,
£84 128. ,, „ 1850,
£50 8. „ 1847-8-9.

During the past year the number of Members who have withdrawn or died amounts
to 45, and 8 Members have been added; so that there are now 709 on the list.

The Council would again urge that the only limits they have to their labours are
the funds derived from their subscriptions, and that just in proportion as these are
increased, are they enabled to publish a larger amount of matter to present to the
Members for their subscription of one guinea per annum.

The Council appointed, last year, J. S. Bowerbank, Esq., Treasurer; and Dr. G.
Johnston, of Berwick-on-Tweed, and Dr. Lankester, London, Secretaries.

REPORT OF THE RAY SOCIETY. 3

Abstract of Treasurer’s Account from June, 1852, to May, 1855.

RECEIVED. £ os, a.
Cash in hand at last audit 8611 6
By subscriptions 542 17 0

£629 8 6

EXPENDED. £5. a

Bookbinding 2915 0
Engraving, printing, &e. 76 15 10
Printing letter-press 226 0 8
Editing 5460
Collector : 2410 7
Books 213 6
Secretary c 125 0 0
Advertising j 833
Local Secretaries’ Expenses . 910 0
Postage, Stationery, &c. 9 611
566 1 4

Cash in hand 638 7 2

£629 8 6

Auditors:

GEORGE SHADLOLT.
JAMES TENNANT.

Moved by Prorgessor BALFOUR; seconded by R. M‘AnpREws, Esq. ;
That the Report now read be adopted, and printed for circulation amongst the

Members of the Society.

Moved by J. Hoge, Esq.; seconded by R. J. Brut, Esq. :
That the thanks of this Meeting be given to the President, Council, Treasurer
Secretaries, Local Secretaries, and Auditors, for their services during the past

year.

Moved by Dr. LEE; seconded by A. STRICKLAND, Esq. :
That the following Gentlemen be requested to act as a Council for the following

year.
ProFESsoR D. T. ANSTED M.A. F.R.S.
F.L.s.
Cuarıes C. Bagınaron, Esq., M.A.
FRS. F.LS.

Rosert BALL, Esq., LL.D. M.R.LA,,
Sec. R.Z.S.I.

Proressor BELL, Sec. R.S., F.L.S.

J. S. BOWERBANK, Esq., F.R.S. F.L.S.

Georce BusK, Esq., F.R.S. F.L.S.

W. B. CARPENTER, M.D. F.R.S.

PRrorFEsSSoR DAUBENY, M.D. F.R.S.

Sır P. de M. G. Ecerron, Bart., m.P.
F.R.S.

Prorsssor Epwarp FOorRBEs, F.R.S.
F.L.S.

PROFESSOR GOODSIR, M.D. F.R.S. L, and E.

A. Hewrrey, Esq., F.R.S. F.L.S.

Sir W. JARDINE, Bart., F.R.S.E. L.S.

Rev. LEONARD JENYNS, M.A. F.L.S.

G. JOHNSTON, M.D. LL.v. F.R.C.S.E.

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PROFESSOR OWEN, D.C.L. F.R.S. F.LS.

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Hist. Soc. Bel. fs

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