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230 W. 25th St., New York.

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PLATE ILLUSTRATING DR. BEALE'S VIEWS,

THE CELL DOCTRINE

ITS HISTORY AND PRESENT STATE.

FOR THE USE OF

STUDENTS IN MEDICINE AND DENTISTRY.

A COPIOUS BIBLIOGRAPHY OF THE SUBJECT.

JAMES T^YSON, M.D.,

Lecturer on Microscopy in tde University of Pennsylvania, and on Physiology

IN THE Pennsylvania College of Dental Surgery; Fellow of the

College of Physicians of Philadelphia, etc. etc.

A COLORED PLATE AND OTHER ILLUSTRATIONS.

PHILADELPHIA:

LIKDSAY & BLAKISTOK

18 70.

R

Entered according to Act of Congress, in the year 1870, by

LINDSAY & BLAKISTON,

In the Clerk's Office of the District Court for the Eastern District of Pennsylvania.

r r r;:,; ;^cA2T0N 'PEERS OP, ^ "^ ;: I

:' ^ r ' 'sKEtekfAlf db Ca.: 'PHlLA£)Ef PHll/

TO

THE MEDICAL CLASS

OF

THE UNIVERSITY OF PENNSYLVANIA,

THIS LITTLE VOLUME

IS RESPECTFULLY INSCRIBED,

BY

THE AUTHOK.

1S422

PREFACE.

The author has become convinced, by several
years' intimate intercourse with students of medi-
cine, that their acquaintance with the subjects he
has endeavored to include in this little volume
would be facilitated, if the views, which are now
taught and scattered throughout the often expen-
sive works of their authors, were collected in a con-
venient form for study and reference. Taking it
for granted that a knowledge of this subject is of
fundamental importance in its bearing upon the
study of physiology and pathology, and stimulated
by the frequent inquiries of students for an appro-
priate source of information, he has prepared what
he now submits to them.

He has sought to obtain a continuous history of
the evolution of the " cell doctrine " up to its present
state, without embarrassing his pages with a large
number of isolated facts. He has attempted, how-

VI PREFACE.

ever, to secure a completeness, and to make the
w^ork useful to physicians and others engaged in
research, by careful references, and the addition of
a bibliography, which he has sought to make accu-
rate and extended. Some authors may have been
overlooked ; such the writer cordially invites to send
him references to their own papers, or to those of
others they believe to have a bearing upon the
subject.

332, South Fifteenth Street.
February, 1870.

ILLUSTRATION^ S.

Plate. — Illustrating Dr. Beale's Views.

Figs. 1 to 7. Production of formed material from germinal matter
in epithelial cells, from section through layer of epi-
thelium covering papillae of frog's tongue.

Figs. 7 to 11. Formation of Pus.

Fig. 11. " " Tendon.

Fig. 12. " " Cartilage.

Fig. 13. " " Muscle.

Fig. 14. " " Elastic Tissue.

Fig. 15. " " Nerve.

Fig. 16. Amoeba.

Fig. 17. Illustrating Nutrition of Cell.

Intercalated.
Fig. 1. Illustrating Globular Theory. After Virchow.

Fig. 2. Cellular Tissue from the Embryo Sac of Chamaedorea
Schiedcana in the act of formation. After Schleiden.

Fig. 3. From the Point of a Branchial Cartilage of Rana Escu-
lenta. After Schwann.

Figs. 4 to 12. Formation of Nuclei and Cells from Molecules, ac-
cording to Bennett.

Fig. 12. Diagram of the Investment Theory. From Virchow.

Vlll ILLUSTRATIONS.

Fig. 13. Formation of Pus from subcutaneous connective tissue.
From Virchow.

Fig. 14. Formation of Pus from interstitial connective tissue of
muscle. From Virchow.

Fig. 15. Development of Cancer from connective tissue. From
Virchow.

Fig. 16. Connective Tissue Corpuscles anastomosing one with the
other. From Virchow.

Fig. 17. Formation of Elastic Tissue, according to Virchow.

THE CELL DOCTRmE.

The idea that animals and plants, however com-
plex their organization, are really composed of a
limited variety of elementary parts, constantly re-
curring, was appreciated by Aristotle, while it ap-
pears to have been even more clearly conceived by
the acknowledged father of medical science, Galen.
Fallopius of Modena, 1523-1562, to whom we are
indebted for our knowledge of the conceptions of
Galen in regard to these "partes similares" or
'^simplices," has further developed the subject of
general anatomy in his " Lectiones de Partibus Simi-
laribus Ilumani Corporis." But these " partes
similares" of Fallopius, which were bone, cartilage,
fat, flesh, nerve, ligament, tendon, membrane, vein,
artery, nails, hairs, and skin, plainly do not corres-
pond with the " elementary parts" or " cells" of the
present day. They were ultimate to Fallopius, as
stated by Prof. Huxley, because he could go no
further, " though it is, of course, a very different
matter whether we are stopped by the imperfection
of our instruments of analysis, as these older ob-
servers were, or by having really arrived at parts
no longer analyzable."* These "partes similares"

* The Cell Theory— a Keview, by T. H. Huxley : Br. & For-
eign Med.-Chir. Rev. for Oct., 1853, No. xxiv.

2

14 THE CELL DOCTRINE.

really correspond to the "tissues" of the present
day, which are collections of elementary parts. The
conceptions of these older writers with regard to the
"vital endowment" or "independent vitality" of
their similar parts or tissues, were singularly correct,
and correspond almost identically with those held by
the majority of physiologists of the present day.

Further than this, however, the anatomists of the
period of Fallopius could not go — not because, as
we now well know, they had arrived at parts no
longer analyzable, but because of their imperfect
means of analysis.

It is probable that the magnifying properties of
lenses were known to the Egyptians, as well as the
Greeks and Romans, over 2000 years ago; since
a table of refractive powers is introduced into his
" Optics" by Ptolemy, since Aristophanes, the comic
Athenian poet (B.C. 500), speaks of "burning
spheres " of glass as sold in the grocers' shops of
Athens, and since both Pliny and Seneca refer to
lenses and their magnifying properties; while lenses
themselves have been found in the ruins of Nineveh,
Herculaneum, and Pompeii. But it is quite certain,
also, that they did not become available as com-
pound microscopes until about 1590, when the Jan-
sens, father and son, of Holland, are said to have in-
vented the compound microscope. Fontana, in 1646,
writes that he had invented the microscope in 1618.
Galileo, as early as 1612, is said to have sent a micro-
scope to King Sigismund of Poland, though whether
it w^as his own invention, or made after the pattern
of another, is more difficult to determine. In 1685

THE CELL DOCTRINE. 15

Stelluti published a description of the parts of a bee
he had examined with the microscope, and although
George Ilufnagle is said to have published in Frank-
fort, in 1592, a work upon insects, illustrated by fifty
copper plates, it is highly probable that these, as well
as very many most important observations made after
the invention of the compound microscope, were
made with the simple instrument.*

It is impossible to estimate the assistance the
microscope has been to us in opening up the minute
structure of animals and vegetables, and in thus af-
fording a reliable basis on which to build a doctrine
of organization. Prof. Huxley says, "The influence
of this mighty instrument of research upon biology,
can only be compared to that of the galvanic battery,
in the hands of Davy, upon chemistry. It has ena-
bled proximate analysis to be uUimate.''1[ But it is
more than this. Since, as he correctly states, it has
enabled proximate physical analysis to become ulti-
mate, it corresponds, not to the galvanic battery
alone, but to all the appliances made use of in ulti-
mate chemical analysis.

The time prior to the invention of the compound
microscope may be considered as the fast period in
histology; that between this date and that of the ob-
servations of Schleiden and Schwann (1838), inclu-
sive, the second period ; while the time subsequent to

* For an interesting and exhaustive history of the invention of
the compound microscope, see Das Mikroskop, Theorie, Gebrauch,
Geschichte und gegenwartigcr Zustand desselben. Von P. Harting
In drei Biinden. Braunschweig : 1866. Dritter Band, ss. 11-35.

f Huxley, loc. citat., p. 290.

16 THE CELL DOCTRINE.

these observations becomes appropriately the third
period. Notwithstanding the imperfect state of in-
struments during quite two hundred years from this
date, a flood of facts was added to our knowledge of
the minute structure of living things.

Borellus, of Pisa, seems first to have used the mi-
croscope in the examination of the higher animal
structures, about the year 1656, but his observations
were grossly misinterpreted in his attempt to adapt
them to the prevailing idea of the day, that diseases
were caused by animalculae in the blood and tissues.
As a result, he describes pus corpuscles as animalcules,
and even says he has seen them delivering their eggs.

According to Boerhaave, Swammerdam had recog-
nized the blood corpuscle in 1658.

Malpighi,* between 1661 and 1665, had witnessed
the circulation of the blood, and had published ob-
servations upon the minute structure of the lungs,
which he had even compared to a racemose gland,t
kidneys, spleen, liver, and membranes of the brain,
and with some of these structures his name has
become inseparably associated. In 1667, Robert
HookeJ pointed out the cellular structure of plants,
and Malpighi§ further elaborated the same subject
with considerable accuracy in his " Anatome Planta-

* Malpighi, Opera Omnia. Lond. : 1686.

f Fort, Anatornie et Physiologie du Pournon, considere comme
organe de Secretion. Paris: 1867, Preface: or a notice of Dr.
Fort's book, by the writer, in American Journal of Medical
Sciences, October, 1869.

J Hooke, Kob., Micrographia. Lond.: 1667.

§ Malpighi, Anatome Plantarum. London: 1670.

THE CELL DOCTRINE. 17

rum," in 1670. He showed that the walls of the
" cells," or " vesicles," were separable, that they could
be isolated; and gave to each the name ^^utriculus,'*
believing also the "cell," or "utriculus," to be
an independent entity. The latter observer* also
recognized the blood .corpuscle. Leeuwenhoek, in
1687,t described these corpuscles with considerable
accuracy, not only in man, but also in the lower
animals. He also demonstrated the capillaries, ex-
amined most of the tissues, and made the discovery
of the spermatozoids, which he conceived to be sper-
matozoa or sperm animals, and of different sexes.

l!^o attempt, however, seems to have been intelli-
gently made at building up the tissues by an ultimate
physical element, to correspond with the "atom" of
the inorganic chemist, prior to that of Haller. He re-
solved the solid parts of animals and vegetables into
the "^6/^6 " (fibra), and an '' organized concreted' To
the former he assigns the most important position,
asserting that it is to the physiologist what the line
is to the geometrician; that a "fibre," in general,
may be considered as resembling a line made up of
points, having a moderate breadth, or rather as a
slender cylinder.f

The second elementary substance of the human
body according to Haller, the " organized concrete,"
must not be lost sight of, as appears to have been

* Malpighi, Opera Posthuma. London: 1697.

f Leeuwenhoek, Opera Omnia seu Arcana Naturae detecta.
Tom. ii, p. 421. Leyden : 1687. Vel Opera Omnia, &c., Lugd.
Batav. : 1722.

J Haller, Elementa Physiologiae, vol. i, lib. i, sect. i. Lausan.
Helvet.: 1757.

18 THE CELL DOCTRINE.

the case with many eminent authorities who have
attempted to give his views. This, he says, is a
mere gUie, evasated and concreted, not within the
fibres, but in the spaces betwixt them, in illustration
of which it is stated, that cartilages seem to be
scarcely anything else besides this glue concreted.
But these views of Haller were clearly not based
upon microscopic observation, though the microscope
had been for some time in use. For Haller himself
tells us that the fibre is invisible, and to be distin-
guished only by the " mind's eye," — invisibilis est ea
abra, sold mentis acie distingidmiis* No allusion to the
cell beyond the imperfect description of the blood
corpuscles and spermatozoids appears to have been
made by Haller.

Better founded, in being based upon observation,
was the theory of Wolf, and it contained many of
the elements of truth. For an available exposition
of these views, physiologists are much indebted to
Prof. Huxley, who in the able review already cited,
has presented them as agreeing partially, also, with

* A singular discrepancy exists between these words of Haller
and those found in both the Latin and English editions of the
" elegant compend " of Haller's works printed in Edinburgh, the
former in 1766, and the latter (an edition in the possession of the
writer), in 1779, under the inspection of William Cullen, M.D.
In the latter, we have the following: <'The solid parts of animals
and vegetables have this fabric in common, that their elements, or
the smallest parts we can see by the finest microscope, are either
fibres or an organized concrete. "i

1 First Lines of Physiology. By the celebrated Baron Albertus Haller,
M.D. Translated from the correct Latin edition, and printed under the
inspection of William Cullen, M.D. Edinburgh : 1779.

THE CELL DOCTRINE. 19

his own. The doctrine of Wolf, as given by Prof.
Huxley, is as follows: "Every organ is composed, at
first, of a mass of clear viscous, nutritive fluid, which
possesses no organization of any kind, but is at moat
composed of globules. In this semi-fluid mass, cavi-
ties (Blaschen, Zellen) are now developed; these, if
they remain rounded or polygonal, become the sub-
sequent cells, if they elongate, the vessels; and the
processs is identically the same, whether it is exam-
ined in the vegetating point of a plant, or in the
young budding organs of an animal. Both cells and
plants may subsequently be thickened by deposits
from the ' solidescible' nutritive fluid. In the plant,
the cells at first communicate, but subsequently be-
come separated from one another; in the animal,
they always remain in communication. In each case
they are mere cavities and not independent entities; organi-
zation is not affected by them, but they are the visible results
of the action of the organizing power inherent in the living
mass, or what Wolf calls the vis essentialis. For him,
however, this vis essentialis is no Archaeus, but -simply
a convenient name for two facts which he takes a
great deal of trouble to demonstrate : the first, the
existence in living tissues (before any passages are
developed in them), of currents of the nutritious
fluid determined to particular parts, by some power
which is independent of all external influence ; and
the second, the peculiar changes of form and com-
position, which take place in the same manner."*

* Huxley, loc. citat., p. 293-4. Wolf, C. F., Theoria Genera-
tionis, 1759. Ed. Nova, 1774.

20 THE CELL DOCTRINE.

Two points are here particularly to be observed as
cardinal, — first, the non-independence of cells, either
anatomically or physiologically; that they are ef-
fects, passive results, and not causes of a vitalizing or
organizing force; second, that organization takes
place from the " differentiation " of the homogeneous
living mass in these parts, through the agency of the
vis essentialis or inherent vital force. The radical
difference between these principles of development
and those generally held at the present day, will be
better appreciated when these latter have been
worked out. An acknowledged error may also be
pointed out, — the probable result of the inferiority of
the instruments of that day — that of supposing the
cells of plants to communicate when in their youngest
state.

This theory, however, full as it was of original
conception, and based on actual observation, seemed
to claim little attention, and would have been still
less known but for the labors of Prof. Huxley. The
" fibre" theory of Haller was still further expanded,
and that fibres were the groundwork of nearly all
the tissues, continued the prevailing view, until the
latter part of the eighteenth century, and there are
few of the older physiologies even of a later date,
which do not contain an account of it. I^aturally,
it maintained itself longest in the case of the fibrous
tissues, since the appearances of these tissues, when
examined by the highest powers, are those of struc-
tures apparently composed of fibres.

The reaction which took place at the date referred
to against the "fibre" theory, culminated in the

THE CELL DOCTRINE. 21

"globular" theory, due less to speculation than er-
roneous methods of observation and imperfect in-
struments. Leeuwenhoek* (1687) early announced
the "globular" structure of the primitive tissues
of the body, but the "globule" apparently attracted
little notice until this period of reaction against the
" fibre," when it claimed the attention of Prochaskaf
(1779), FontanaJ (1787), the brothers Wenzel§ (1812),
Treviranusll (1816), Bauer1[ (1818 and 1823), Heu-
singer** (1822), MM. Prevost and Dumas,tt Milne-
Edwardstt (1823), Hodgkin§§ (1829), Baumgart-

* Leeuwenhoek, op. citat.

f Prochaska, De Structura Nervorum. Vind. : 1779. Opera
min., Pars i.

I Fontana, Sur les Poisons, 1787, ii, 18; Abhandlung iiber das
Viperngift, das Amerikanische Gift, u. s. w. Aus dem Italien.
Berlin: 1787.

^ Wenzel, Joseph and Charles. De structura cerebri. Tubing. :
1812.

II Treviranus, Verraischte Schriften, Anatom. und Physiolog.
Inhalts. Bd. i. Gottingen: 1816.

^ Bauer, Philosoph. Transac. for 1818, and Sir E. Home's Lec-
tures on Comparative Anatomy. Vol. iii, Lect. iii. London : 1823.

** Heusinger, System der Histologic. Thl. i, Eisenach: 1822-4.

If MM. Prevost and Dumas, Bibliotheque Universelle dcs Sci-
ences et Arts, T. xvii.

ll Milne-Edwards, Memoire sur la Structure Elementaire des
Principaux Tissues Organiques des Aniraaux. Paris: 1823. Also,
Kecherches Microscopiques sur la Structure Intimo des Tissues Or-
ganiques des Animaux, in Ann. des Sci. Nat., Dec, 1826.

g^ Hodgkin, in Grainger's Elements of General Anatomy. Lon-
don : 1829. Also, Hodgkin and Fisher's translation of M. Edwards
" Sur les Agens Physiques." London: 1832. Hodgkin 's Lectures
on the Morbid Anatomy of the Serous and Mucous Membranes.
London: 1836, p. 26. Am. Ed. Philada. : 1838, vol. i, pp. 17-18.

22 THE CELL DOCTRINE.

ner* (1830), F. Arnoldf (1836), DatroclietJ (1837),
Kaspail§ (1839); all except Hodgkin admitting in
greater or less degree the importance of the globule
as an ultimate physical element ; while it is evident,
also, that there was much confusion in the use of
terms, — the words globule, granule, and molecule,\\
being often indiscriminately used, and the word
globule sometimes used to indicate what is now clearly
recognized as the "cell."

Prochaska,T[ in 1779, described the brain as made
up of globules eight times smaller than blood glob-

* Baumgartner, R. H., Lehrbuch der Physiologie mit Nutz-
anwendung auf die arztliche Praxis. 1853.

f Arnold, F., Lehrbuch der Physiologie des Menschen. Erst.
Theil, Zurich: 1836.

X Dutrochet, M6nioires pour servir a I'Histoire Anatomiqueet
Physiologique des Vegetaux et des Animaux. T. i, ii, Atlas.
Paris: 1837.

g Easpail, Systeme de Chimie Organique. 2e cd., T. i, ii.
Brus. : 1839. Avec Atlas.

II The German authors of this period and even more recent
times (Henle, 1841, Virchow, 1858), at least in speaking of the
development of histology, seem to use indiscriminately the terms
granule or molecule, and globule, whereas they are morphologically
something distinct. A globule is usually held to be a body,
which, under the microscope, is more or less spherical in form,
possessing a bright centre, and dark outline, — the width of this
outline being directly as the difference between the refracting
power of the globule itself and that of the menstruum in which it
floats. Thus, the dark outline of a globule of oil floating in water
is wider than that of the same globule floating in glycerine. A
granule or molecule, on the other hand, is indeterminate in size and
shape, and appears as a mere dot under the highest powers of the
microscope. It is true that what appears as a granule under a low
power, may appear as a globule under a higher.

^ Prochaska, Opera Minora, Part I, p, 342.

THE CELL DOCTRINE. 23

ules. In the year 1801, the philosophic mind of
Bichat elaborated his excellent classification, but
he seems to have made no original investigations in
minute structure, or to have adopted any special
theory of an ultimate physical element. The bro-
thers Joseph and Charles Wenzel,* in 1812, de-
scribed the brain as composed of globules of small
size. Among the earliest histologists worthy of
mention, is Treviranus,f whose elements, according
to Henle, were first, a homogeneous, formless matter;
second, fibres; third, globules (kugelchen). Mr.
Bauer,J quoted as a most experienced microscopic
observer by Sir Everard Home, in 1818, and again
in 1823, described the ultimate globules of the brain
and of muscular fibre as of the size of a globule
of blood when deprived of its coloring matter, or
about 2 0^0 0 ^^ ^^^ i^^^ i^ diameter. The fibre was
excluded as an ultimate element of organization
by Heusinger§ in 1822-4, who started all tissues
from the globule, still, however, retaining the form-
less material of Haller and Treviranus. Heusinger
formed the fibre by the linear apposition of his
globular elementary parts, and even explained how
canals and vessels were formed by a similar ar-
rangement of vesicles which had originated from the
globules. The account given by Henle|| of the
method in which Heusinger built up his fibres and
vessels is interesting, and is worth translating, since

* Wenzel, op. citat., p. 24. f Treviranus, op. citat.

X Bauer, op. citat. § Heusinger, op. citat., p. 112.

II Henle, Allgemeine Anatomie. Leipzig : 1841, p. 128.

24 THE CELL DOCTRINE.

there is in these views an approximation to the truth.
"As the result of an equal contest between contrac-
tion and expansion, there arises the globule, of which
all organisms, all organic parts, are originally com-
posed. By a stronger exercise (Spannung, tension)
of power, there originates from the often mere homo-
geneous globule, the vesicle. Where in an organism
globules and ^formless mass are present, the globules
arrange themselves according to chemical (?) laws
and form fibres. Where vesicles arrange themselves,
there arise canals and vessels.'^ In the latter sen-
tence one cannot fail to note a close approximation
to the truth, though the facts upon which the theory
was based are partly false and partly misinterpreted.
But the observations and writings of Milne Ed-
wards* may be looked upon as having given, more
than any other author, position and popularity to the
" globular theory." lie examined all the principal
tissues, and announced that the fibres of the then so-
called cellular (fibrous) tissues, membranes composed
of these fibres, muscle and nerve, were composed
of globules of about the same size, from gJ^^ to
■rsuo of an inch in diameter; whence he concluded
that these spherical corpuscles, by their aggregation,
constituted all organic textures, vegetable or animal,
and whatsoever their properties or functions. There
is little doubt but that many of these so-called glob-
ules described by Edwards were really cells, seen
with indifi:erent instruments, and further distorted by
the glare of direct sunlight.

* Edwards, loc. citat.

THE CELL DOCTRINE. 25

Similar, as regards the element of organization,
were the views of Baumgartner* and Arnold,! who
built up the cell wall by the apposition of globules
(to which the term granules would now perhaps be
appliedj), so as to constitute a membrane within
which other globules (granules) remained to consti-
tute contents.

Fio. 1.

Fig. 1. Illustrating the globular theory.

A, Fibre, composed of elementary granules (molecular granules), drawn
up in a line. B, Cell, with spherically arranged granules. (After Vir-
chow, slightly modified.)

The error of Edwards seems to have been clearly
pointed out by Dr. Hodgkin,§ though much impor-
tance was still attached to the globule as an element
of organization (but perhaps from this time forward,
more in the stricter sense of the term granule), which
has continued, in this latter sense, to the present day.

From the foregoing facts, it is evident that for some
time prior to the year 1838, the cell had come to be
quite universally recognized as a constantly recur-
ring element in vegetable and animal tissues, though
as yet little importance had been attached to it as an
element of organization, nor had its characters been

* Baumgartner, loc. citat ; also, Virchow, Cellular Pathology,
Am. Ed. of Chance's Translation. Philada. : 1863, p. 53.

j- Arnold, loc. citat. ; also, Virchow, Cellular Pathology, Am.
Ed. of Chance's Translation. Philada. : 1863, p. 53.

I See note to p. 22. g Hodgkin, loc. citat.

3

26 THE CELL DOCTRINE.

clearly determined. As stages in its growing impor-
tance may be mentioned, the demonstration of the
cellular structure of plants by Robert Hooke in 1667,
the further elaboration of this subject by Malpighi,
and his statement that each "utriculus" was an in-
dependent entity, the description of Heusinger, in
1822, of the mode of formation of vessels by the appo-
sition of vesicles, already referred to, and the announce-
ment, though erroneous, of Dbllinger, in 1828, that
the body is built up of blood corpuscles which move
in wall-less (wandlos) channels in the tissues.

A most important contribution to the anatomy
of the cell was now made, in the discovery of the
" nucleus," by Dr. Eobert Brown, of Edinburgh ;
whose paper, " Organs and Mode of Fecundation in
Orchid^se and Asclepiadese," appeared in the Trans-
actions of the Linnean Society of London, in 1833.
He failed, however, to appreciate its importance,
though its discovery was another fact added to those
necessary to complete the data on which has been
founded the so-called " cell theory."

Singularly near the truth did Easpail* approach,
in 1837, when he tells us that in the condition of
development there are vesicles or cells, endowed
with life and the property, almost unlimited, of pro-
ducing out of themselves other cells of the same
structure and similar endowments, of spherical form,
and capable of taking up oxygen when exposed to
the atmosphere; that the cell membrane in its fresh
state is structureless. Yet he considers the organic

* Kaspail, op. citat.

THE CELL DOCTRINE. 27

cell as made up of granules or atoms, spirally ar-
ranged about an ideal axis, comparing the cell with
the crystal rather than the ultimate element or atom
of which the crystal is made up, and speaks of or-
ganization as crystallization in vesicles {crystalliza-
tion vesiculaire).

Similar was the view of Dutrochet,* who divided
the component parts of the body into solids smd fluid.
The solids were formed by the aggregation of cells of
a certain degree of firmness; the liquids, as the blood,
are also made up of cells/ which, however, float freely
among each other, and there are also tissues in which
the cells are so feebly united, that one can scarcely
tell in what class to place them. The contents of the
cell may be more or less solid, but the highest degree
of vitality is only compatible with liquid cell contents.
Muscular fibres, and the remaining animal fibres, are cells
much elongated. And he considers the same general plan
to prevail in the animal and vegetable. The approach of
both of these observers to the truth is striking.
Both, however, either failed to detect the nucleus or
to attach any importance to it. They failed also to
lay down a law of organic development. Hence their
views were soon forgotten.

Since the discover}^ of the nucleus, by Dr. Robert
Brown, in the vegetable cell, it had been recognized
by many observers in various pathological, as well as
healthy animal cells, and in the germ cell or ovule
of birds, as early as in 1825, by Purkinje; while

* Dutrochet, op. citat.

28 THE CELL DOCTRINE.

Purkinje,* Yalentin,t and TurpiuJ had actually
called attention to the relations of the animal and
vegetable cell to each other.

The preexistence of the nucleus, and the gradual
development of the cell about it, Valentin- had at-
tempted to demonstrate in the case of pigment cells,
C. H. Schultz in the blood corpuscle, Rudolph
Wagner in the egg, and Henle in epithelium, all
before the work of Schleiden had appeared. Valen-
tin, too, had said, when describing the nucleus of
epidermic cells, that they reminded him of the nu-
cleus of the cells of vegetable tissues.§ ISTot only
this, but Armand de Quatrefages|| and DuraortierTf
had actually observed the origin of young cells from
the full grown, in the embryo of the freshwater snail,
while Valentin had furnished examples of the devel-
opment of fibres out of cells in muscular fibre, and
in the substance of the crystalline lens. In fact, as
stated by Dr. Waldo J. Burnett, in his admirable
paper,** Valentin " perceived the true physiological

* Purkinje, in Kaschkow, Meletemata Circa Mammalium Den-
tium Evolutionem. Diss. Inaug., Wratis. : 1835, p. 12.

f Valentin, Ueber den Verlauf und die Enden der Nerven, aus
den Nov. Act. Nat. Curios., vol. xvii: besonders Abgedruckt.
Bonn: 1836.

J Turpin, Ann. d. Sci. Nat., 2. ser. vii, 207.

g Valentin, Nov. Act., N". C, xvii, pt. I, p. 96.

II Quatrefages, Annales des Sci. Nat., 2 ser. ii, p. 114.

][ Dumortier, Annales des Sci. Nat., 2 ser. vii, p. 129.

** Burnett, W. J. The Cell ; its Physiology, Pathology, and
Philosophy, as deduced from original investigations. To which
is added its history and criticism. A prize essay, read before the
American Medical Association, and published in vol. vi of its
Transactions. Philadelphia: 1853.

THE CELL DOCTRINE. 29

relations of cells as far as he well could without ap-
prehending the grand fact that the nucleated cell is
the fundamental expression of organic forms."

SCHLEIDEN AND SCHWANN.

It was reserved for Schwann to accomplish this
master stroke in observation and generalization,
through the intermediate results of Schleiden, with-
out whose observations on vegetable structures,
the true position of the cell would probably have
remained undetected for some time longer. Schlei-
den, in 1838, clearly pointed out the formation of
cells in vegetable structures, according to a single
and uniform method, and elaborated the theory of
development of which the cell was the unit, and
which Schwann immediately'' extended to animal tis-
sues.

A formidable obstacle for some time in the way of
a law of development, applicable to animal and veg-
etable tissues, was the opinion, long entertained, that
the growth of animals whose tissues are furnished
with vessels is essentially different from that of
plants; an independent vitality being ascribed to the
elementary particles of vegetables growing without
vessels. So firmly was this believed, that the ovum
which exhibited undoubted evidences of an actual
vitality at one period of its growth, was said by all
physiologists to have had a plant-like growth. This
obstacle was removed in 1837, by Henle,* who showed

* Henle, Symbolae ad Anatomiam vill. intest. Berol. : 1837.

3*

30 THE CELL DOCTRINE.

that an actual growth of the elementary parts of epi-
thelium took place without vessels.

Taking up the nucleus as discovered by Robert
Brown, Schleiden,* in reference to its function, ap-
plies the name cytoblast (xwtoc, a cell, (SXaffvoq^ a
bud or sprout), or " cell bud," and in a careful study
of its anatomy, discovers that "in very large and
beautifully developed cyloblasts, there is observed
a small, sharply defined body, which, judging from
the shadow which it casts, appears to represent a
thick ring, or thick-walled hollow globule."t One,
two, three, and even four of these may be present.
Without further present comment than that these
characters, as given by Schleiden, are by no means
constant, it is plain that what is commonly known
as the nucleolus is here intended, to the discovery of
which we are therefore indebted to him, though
Valentin also claims its discovery at an earlier
period.! ^1^ further states that the observations he
has made upon all plants, lead him to the conclusion
that these small bodies are found earlier than the
cytoblasts.

According to Schleiden, when starch is to be em-

* Schleiden, Beitrage zur Phytogenesis, Muller's Archiv, 1838,
p. ii ; Contributions to Phytogenesis, Sydenham Soc. Transl., p.
233.

f The term nucleolus or nucleus-corpuscle (Kernkorporchen),
seems to have been first applied by Schwann. (See Introduction
to Schwann's Kesearches, Syd. Society's Translation.)

X Valentin, "Outline of the Development of Animal Tissues,"
in Wagner's Elements of Physiology, Translated by Dr. Willis.
London : 1844, p. 214. Leipzig : 1839 ; — where he refers to Val-
entin's Repertorium, vol. i, p. 143.

THE CELL DOCTRINE. 31

ployed in new formations, it becomes dissolved into
sugar or gum, which are convertible into one another.
The sugar appears as a perfectly transparent fluid,
not rendered turbid by alcohol, and receiving from
tincture of iodine only so much color as corresponds
to the strength of the solution. The gum is some-
what yellowish, more consistent, less transparent,
and coagulated into granules by tincture of iodine,
assuming a pale yellow color which is permanent.
In further progress of organization, in which the
gum is always the last fluid, a quantity of exceed-
ingly minute granules appears in it, most of which,
from their exceeding minuteness, appearing as black
points. Here it is that organization takes place,
though the youngest structures are composed of
another distinct homogeneous, perfectly transpa-
rent substance — so transparent as to be invisible
when not surrounded by opaque or colored bodies,
— and continuing thus after pressure. This he calls
vegetable gelatine, and considers as slight modifica-
tions, pectin, the basis of gum tragacanth, and many
of the substances usually enumerated under the term
vegetable mucus. It is this gelatine which is ulti-
mately, through the agency of the nucleus, converted
into the actual cell-wall, or structures which consist
of it in a thickened state, and into the matter of
vegetable fibre.

In this homogeneous blastema or cytohlastema (said
to be most easily studied in the embryo sac, and in the
extremity of the pollen tube), are very soon precipi-
tated or developed mucous or protein granules, when
the solution immediately becomes cloudy and more

32

THE CELL DOCTRINE.

B o

or less opaque. Single, larger, more sharply defined,
granules next become apparent, A, ^g. 2, constituting
the nucleoli, about which the smaller
granules soon collect to form the
nuclei or cytoblasts, B. These then
grow considerably in the free state,
C, but so soon as they have at-
tained their full size, a delicate,
transparent vesicle rises upon their
surface, assuming the relation of the
watch crystal to a watch, D, E.
Thus is constituted the j^oung cell.
The vesicle gradually expands and
becomes more consistent, and with
the exception of the cytoblast,
which always forms a portion of it,
the wall now consists of gelatine.
The entire cell then increases be-
yond the margin of the cytoblast,
and quickly becomes so large that
the latter at last merely appears as
a small body inclosed on one of the
side walls. In this manner, we have
exogenous free cell formation. With-
in these cells, again, as well as in
the homogeneous blastema about
them, new cytoblasts arise, grow,
and form young cells which grow and fill up the mother
cells, and finally cause them to disappear. This is
endogenous cell formation. According to Schleiden
"the entire growth of the plant consists only of a
formation of cells within cells." No other method

P E

Fig, 2. Cellular Tis-
sue, from the embryo
sac of Chamaedorea
Schiedeana, in the act
of formation.

A, Formative sub-
stance, gum, mucous
granules, nuclei of cy-
toblasts (nucleoli).

B, Cytoblasts.

C, Single and free cy-
toblast more highly
magnified.

D, Cytoblast with
cell forming in it.

E, Same more highly
magnified.

F, Cytoblast isolated
after destruction of cell.

From Schleiden —
Beitrage zur Phy togen-

THE CELL DOCTRINE. 33

of formation of new cells seems to have been con-
ceived by him. For although the multiplication of
cells by fissiparous division of previously existing
cells, had been demonstrated by Mirbel,* and con-
firmed by Von Mohl,t before the investigations of
Sehleiden had been made, the latter author considered
the apparent growing across of the partition cells an
illusion, and that the young cells escape observation
in consequence of their transparency, until, at a late
stage, their line of contact is regarded as the partition
wall of the parent cell; while even Schwann states
somewhat hesitatingly what is now so generally ad-
mitted.J This is the cell theory of Sehleiden, which
has also been properly called the theory of free cell
formation, since it involves a spontaneous generation
of the cell.

The merit of Schwann consisted in applying this
theory to animal tissues, his conclusions being based
upon the study of the formation of the chorda dor-
salis, and cartilage, and a comparison of their cells
with those of vegetable tissues. Thus, in a cyto-
blastema, either structureless or minutely granulous,
"a nucleolus is first formed; around this a stratum
of substance is deposited, usually minutely granulous,
but not yet sharply defined on the outside. As new
molecules are constantly being deposited in this stra-
tum between those already present, and as this takes
place within a precise distance of the nucleolus only,

* Mirbel, Recherches sur la Marchantia, 1833.
f Von Mohl, Entwicklung und Bauder Sporen der Kryptogam.
Gew., Flora, 1833.

X Schwann, op. citat. Introduction, p. 4.

34 THE CELL DOCTRINE.

the stratum becomes defined externally, and a cell
nucleus having a more or less sharp contour is formed.
The nucleus grows by a continuous deposition of
new molecules between those already existing, that
is by intussusception. (See Fig. 3, e.) If this go on
equally throughoutthe entire thickness of the stratum,

Fio. 3.

Fig. 3. From the point of a^branchial cartilage of Rana esculenta.
(From Schwann.)

the nucleus may remain solid; but if it go on more
vigorously in the external part, the latter will become
more dense, and may become hardened into a mem-
brane, and such are the hollow nuclei."*

When the nucleus has reached a certain stage of
development, the cell is formed around it. The fol-
lowing is the process by which this takes place : —
"A stratum of substance, which differs from the cyto-
blastema, is deposited upon the exterior of the nu-
cleus. (See Fig. 3, d.) In the first instance, this
stratum is not sharply defined externally, but be-
comes so in consequence of the progressive deposition
of new molecules. The stratum is more or less thick,
sometimes homogeneous, sometimes granulous: the

* Schwann, op, citat., p. 176.

THE CELL DOCTRINE. 35

latter is most frequently the case in the thick strata
which occur in the formation of the majority of ani-
mal cells. We cannot, at this period, distinguish a
cell cavity and cell wall. The deposition of new
molecules between those already existing proceeds,
however, and is so effected that when the stratum is
thin, the entire layer, and when it is thick, only the
external portion, becomes gradually consolidated into
a membrane. The external portion of the layer may
become consolidated soon after it is defined on the
outside ; but, generally the membrane does not be-
come perceptible until a later period, when it is
thicker and more defined internally; many cells,
however, do not exhibit any appearance of the for-
mation of a cell membrane, but they seem to be solid,
and all that can be remarked is that the external por-
tion of the layer is somewhat more compact.*

"Immediately that the cell membrane has become
consolidated, its expansion proceeds as the result of
the progressive reception of new molecules between
the existing ones; that is to say, by virtue of a growth
by intussusception, while at the same timie it becomes
separated from the cell nucleus The in-
terspace between the cell membrane and the cell
nucleus is at the same time filled with fluid, and this
constitutes the cell contents. During this expansion
the nucleus remains attached to a spot on the internal
surface of the cell membrane." Though, according to
Schwann, in animal cells the nucleus is never covered
by a lamella passing over its inner surface, as is the

* Schwann, op. citat, p. 176.

36 THE CELL DOCTRINE.

case with the vegetable cell according to Schlei-
den. Thus is formed the animal cell according to
Schwann, and although its method is identical with
that of Schleiden, both as to endogenous and ex-
ogenous cell formation, we have quoted his own
paper, because he is plainly fuller, and more precise
in his descriptions. The object of each observer was,
however, the same with regard to the tissues studied;
the additional object of Schwann being to show that
all organisms, ivhelher animal or vegetable, are formed on
a common principle, a7id that this principle is origin from
cells, — that the various tissues of the plant and animal,
however simple or complicated, are all combinations
of these cells, modified in adaptation to the special
peculiarities of tissues.

The conception of Schleiden was truly original,
though its application was less difficult in conse-
quence of the simplicity of vegetable tissues. The
conception of Schwann was easier, in being the re-
flection of that of Schleiden, while its application was
more difiicult, in consequence of the great diversity of
animal tissues; so difiicult that he acknowledged that
"there are some exceptions, or at least difterences,
which are as yet unexplained." This need not sur-
prise us when we recollect that one of the ablest
modern exponents of the cell theory, admits the diffi-
culty of its application to some of the so-called higher
tissues.* Indeed, the careful reader of Schwann's
researches cannot but be surprised at the accuracy
of the observations of this histologist, nor can he

* Virchow, Cellular Pathology, Chance's Translation. Am.
Edit., Philada. : 1863, p. 78.

THE CELL DOCTRINE. 37

fail to realize how comparatively few have been the
changes necessitated in his descriptions, or the method
of application of his theory to the formation of the dif-
ferent tissues. Indeed, the portion of the theory of
Schleiden and Schwann which does not accord with
the latest expression of the cell doctrine, is not so
much that which pertains to the formation of tissues
from existing cells, as that which relates to the
method in which they supposed the cells to origi-
nate; which, it will be recollected, was by a species
of spontaneous generaiioii of the essential parts of the
cell, in a homogeneous cytoblastema.

A difterence in the anatomy of the cell as given by
Schwann, and physiologists of the present day is
seen in the location of the nucleus by the latter, who
places it not merely eccentrically, but actually " sepa-
rated from the surface only by the thickness of
the assumed cell-wall;"* though an inspection of
Schwann's drawings would not convey this impres-
sion. At the present day, the situation of the nu-
cleus, though usually central, is known to be not
unvarying. Again, the primary and absolutely es-
sential presence of the nucleolus, as well as the uni-
versal presence of the cell-wall, may be considered
characteristics of Schleiden and Schwann's idea of
the cell, which are now no longer insisted upon.

As already stated (p. 33), Schwann would seem
to have admitted also, the formation of cells by
division, though with some hesitation. Thus he
writes :t "A mode of formation of new cells, differ-

* Schwann, op. citat., p. 37, a. f.
f Schwann, op. citat., Introduction, p. 4.
4

38 THE CELL DOCTRINE.

eiit from the above-described, is exhibited in the
multiplication of cells by division of the existing
ones; in this case, partition-walls grow across the old
cell, if, as Schleiden supposes, this be not an illusion,
inasmuch as the young cells might escape observa-
tion in consequence of their transparency, and at a
later stage, their line of contact would be regarded
as the partition-wall of the parent cell."

It would be easy to point out other defects in the
theory of Schleiden and Schwann, when it is tested
by comparison with the more accurate observation
of the last twenty-five years, none of w^hich should
be permitted to detract from the credit which at-
taches to the originators of this conception. It must
not be forgotten, that it is no less true of science than
of art, that great and important truths in their en-
tirety, are gradually' developed, and that no single
mind is capable of elaborating them from their in-
cipiency to their complete expression. And, since
many clever people had daily noticed the rising of
steam from the boiling kettle without thinking of
utilizing its principle of expansion, so many careful
observers had time and again witnessed the cellular
or vesicular composition of plants, and yet failed to
appreciate the importance of the nucleated cell, and
to deduce from it a law of development applicable to
all organic forms. Again, as the engine of Watt
was far different from the beautiful and powerful
creation of the mechanic of the present day, so the
cell theory, as developed by Schleiden and Schwann,
has been further evolved by later histologists. So
that we may truthfully reiterate, with Prof Huxley,

THE CELL DOCTRINE. 39

" whatever cavillers may say, it is certain that histol-
ogy before 1838, and histology since then, are two
difterent sciences — in scope, in purpose, and in dig-
nity— and the eminent men to whom we allude,
may safely answer all detraction by a proud ' circum-
spiee.' "*

According to these observers, then, a perfectly-
formed cell would be defined as a closed vesicle, with
certain contents, among which were essentially a nu-
cleolus and nucleus,

HENLE, 1841.

It is not consistent with our object to include all
of the numerous observations which were multiplied
after this period, incited by the researches of Schlei-
den and Schwann. It is simply to point out the
salient features of those results which point towards,
and have culminated in accepted views. It has
been stated that previous to Schleiden's researches,
in 1838, the formation of cells by division had been
asserted as one mode of origin of cells, that Schlei-
den had declared this an error of observation, and
that Schwann had hesitatingly, if at all, accepted it
as a rare method of cell formation.

IIenle,t who, in general, adopted the view of
Schwann as to the jmmary origin of cells, though he
made exception to its universality of application,
says that cells multiply in three ways :

1. By budding (durch Sprossen), as in certain lower
plants.

* Huxley, op. cit., p. 290.

•}• Henle, Allgemeine Anatomie. Leipzig : 1841, p. 172 et seq.

40 THE CELL DOCTRINE.

2. By endogenous cell development (durch endo-
gene Zeugung), where the cell contents of the mo-
ther cell become the cj^toblastema of the daughter
cells, as originally given by Schleiden and Schwann.

3. By division or segmentation (durch Theilung),
of which he says, however, no examples are found
among animals; though he also states in the para-
graph* immediately following, "We would, with
Schwann, consider cell formation in the yolk, by
* farrowing,' an analogous process, if we may con-
sider the yolk as a simple cell." He then proceeds
to describe how, by a "cording in"t of the surface,
the yolk is divided into two equal parts, these into
four, and so on until the entire yolk becomes a mul-
berry mass, made up of little round bodies. This seg-
mentation of the ovum already observed in the yolks
of frogs, fish, molluscs, and medusae, Henle says at
this time (1841), has perhaps merely escaped noticej
in the case of the higher animals, as plausibly sus-
pected by Bergman, — a suspicion which we need
scarcely say was amply confirmed a little later. But
Henle also states, in the same connection, that certain
cases arise in which perfect cells are developed in a
cytoblastema, in a manner w^hich is inexplicable,
and that from these cells, tissues are finally devel-
oped. § Whence the undetermined state of the question

* Henle, op. cit., p. 176.

I Einschniiren, to cord (a box, &c.), to bind with a cord, to
string. Orieb.

X Henle, op. cit., p. 177.
§ Henle, op. cit., p. 177.

THE CELL DOCTRINE. 41

at that time may be easily inferred.* J^or is mention
here made by Henle, of the nucleus of the cell, as the
primary seat of the segmentation. The surface of the
cell is said to be " corded in," or "furrowed," deeper
and deeper, until the division takes place. This de-
scription is still adhered to by many physiologists
of the present day, who consider that there is a sim-
ple disappearance of the germinal vesicle or nucleus
of the ovum after fecundation, rather than a division
of it into two, and substitution of these for the orig-
inal one.

* While endeavoring to trace out the steps by which the present
most generally accepted views with regard to the origin of cells, were
arrived at, it must not be forgotten that other dissenting views were
also advanced, though tending differently from those incorporated
in the text, where it is desired more particularly to trace those
culminating in existing doctrines. Thus did Reichert^ early (1840),
dissent from Schwann, since he failed to find the nucleus univer-
sally present in the yolk. Karsten2 (1843), published a dissertation
upon the cell, in which he stated that cells originate without a pre-
existing nucleus, and by the expansion of amorphous granules of
organic matter; and more recently (1863), the same author practi-
cally reiterates this view, since he says that all " cells of vegetables
originate as minute free vesicles in the fluid contents of previously
existing cells," and regards the nucleus as a "small tertiary cell,
retarded in its development."^ Again, "when the nucleus is
present, the origin of new cells is quite independent of it."* In
addition to the statement contained in the text, Henle also (1843),
alleged that some of the so-called fibrous tissues were "formed by the
aggregation of granules in a certain way without the intervention

1 Reichert, Das Entwickelungslebun im Wirbelthlerreich. Berlin: 1840,
pp. 6, 9.3. -

2 Karsten, De Cella vitale Dissertatio. Berlin : 184.3.

3 Karsten, Ann. and Mag. of Nat. History, vol. xiii, p. 268. London ;
1864.

* Karsten, Ann. and Mag. Nat. History, vol. xiii, p. 281.

4*

42 THE CELL DOCTRINE.

MARTIN BARRY, 1840.

It was in his first series of embrjological researches,
published in Part II, of the " Philosophical Transac-
tions " of London, for 1838, p. 310, that Dr. Martin
Barry declared "that the germinal vesicle (which he
regarded as the nucleus), and its contents constitute
throughout the animal kingdom the most primitive
portion of the ovum." In his second series. Part
II, 1839, in stating that the germinal vesicle returns
to the centre of the cell, 'post coitum, he first pointed
out that the nucleus does not always accompany the
cell through the whole vital process at the periphery
(the original position according to Schleiden and
Schwann), but that it also passes to the centre, as
we now well know. Here, also, he declares, but in
bis third series, Part II, 1840, he demonstrates that
there arise in the parent vesicle, two or more infant
vesicles, the parent vesicle disappearing by liquefac-

of true nucleated cells."! Kolliker,2 one of the foremost exponents
of the cell doctrine of the present day, in 1844 expressed his dissent
from the idea of unity in the mode of cell formation, and states that
if there is a single method of cell formation which is invariable,
it remains to be discovered. Mr. Paget,^ so well known from his
Lectures on Surgical Pathology, suggested in 1846, that a cell
might arise in some other way than from a nucleus, since he had
met morbid growths composed entirely of fibres, in which not a
nucleated cell was present. Most of which statements are, how-
ever, reconciled by the information which has since been added to
our knowledge of the subject.

1 Henle, Traite d'Anatomie Qenerale. Trad. d'Allemand, par A. J.
Jourdain, 2 vol. Paris : 1843, torn. 1, p. 374.

2 Kolliker, Entwickelungsgeschichte der Cephalapoden. Zurich : 1844.

3 Paget, Report on the Progress of Anatomy and Physiology. Br. and
For. Med. Rev., July, 1846.

THE. CELL DOCTRINE. 43

tion. And in his third series, p. 529, he says, " The
germinal vesicle does not burst, or dissolve away, or
become flattened on or before the fecundation of the
ovum as hitherto supposed. It ceases to be pellucid."
And on page 531, " The germinal vesicle tills with
cells, and these become filled with the foundations
of other cells; so that the germinal vesicle is gradu-
ally rendered opaque."

He also describes in this series, in great detail, the
mode in which these cells are produced from the
germinal spot, which he considers in the light of a
nucleus to the germinal vesicle. Part II, 1839, p. 360.
And though the minute details may not precisely
accord with those of the most recent observations,
the correct idea is clearly grasped. In fact, it may be
said that in minuteness of detail alone does he differ
from later observers, and had he simply stated that
the young cells arise from the nucleus or nucleolus of
the parent cell, he would accord precisely with the
most recent observers. But he is, if possible, even
more explicit when he says, "The process inherited
from the germinal vesicle by its offspring, reappears
in the descendants of these. Every cell, whatever its
minuteness, if its interior be discerned, is filled with
the foundations of new cells, into which its nucleus
has been resolved." Again he says,* " Schleiden has
seen the nucleus undergoing such changes (division),
but failed to recognize them." And finally, in "Phi-
losophical Transactions" for 1841, pp. 207-8, we
have the following striking paragraphs, which would
seem also to correct some previous errors :

* Barry, Philosophical Transac, 1840, p. 348, g 385.

44 THE CELL DOCTRINE.

" § 77. I am very much inclined to believe, that in
the many instances in which authors on ^ cells' have
described and figured more than one nucleolus in a
nucleus, there has been either an hicipient division
of the nucleus into discs, or the nucleus has consisted
of two or more discs; the nucleoli of those authors
having been the minute and highly refracting cavi-
ties or depressions in the discs. If this has really
been the case, it affords additional evidence, I think,
that reproduction of cells hy the process I have described —
namely^ division of the nucleus of the parent cell — is uni-
versal— so numerous have^een the instances in
question. I may refer to the figures given by
Schwann, who examined nearly every tissue, and to
those of Schleiden, whose observations have been so
extensive on plants. I think, indeed, that many of
the figures of Schwann afford evidence of the divi-
sion in question having taken place. It is to be
recognized in his delineation of the cells of cartilage,
cellular tissue, middle coat of the aorta, muscle,
tendon, the feather, &c. The same remark is appli-
cable to a figure given by Reichert of ciliated epithe-
lium cells. Dr. Henle found that in the layers of
his ' pflaster-epithelium ' cells, the nucleus, very dis-
tinct in the lower cells, had almost disappeared in
those situated in the upper part. From this obser-
vation, and from the presence of two nucleoli in some
of the nuclei figured by this observer, as well as from
the nucleus becoming more granular, I think it ex-
tremely probable that these cells (including those of
the epidermis), are reproduced by the process just
referred to — division of the nucleus; additions being

THE CELL DOCTRINE. 45

no doubt continuously made at the lower part of the
layer, by ' which cells previously there are pushed
farther out.'

" § 83. The nuclei which various observers have
found lying among the fibres of various tissues, have
been considered by them as the ^remains of cells.'
This may have been the case, but so far from think-
ing with those observers, that the nuclei in question
were * destined to be absorbed,' I am disposed to
consider that they were sources from which there
would have arisen new cells."

Without doubt, we can say, as did Goodsir,* in the
above by Martin Barr}^ we have the " first consis-
tent account of the development of cells from a parent
centre, and more especially of the appearance of
centres within the original sphere." JS^othing more
definite, or directly to the point, could be desired,
and we think it may be justly said of Barry, that he
completed the expression of the cell theory inaugu-
rated by Schleiden and Schwann, in modifying the
mode of origin to conform to most recent observa-
tion. I

PROF. JOHN GOODSIR, 1845.

In 1845, Prof. John Goodsir published his paper
on "Centres of I^utrition,"t in "Anatomical and
Pathological Observations," in which he clearly
grasped the two important principles of the modern
Cellular Pathology; first, the activity of these centres

* Goodsir, Turner's Edition of Anatomical Memoirs. Edin-
burgh : 1868. Note on p. 390.
f Goodsir, op. citat., p. 389.

46 THE CELL DOCTRINE.

(nuclei), their power " to draw from the capillary
vessels, or from other sources, the materials of nutri-
tion, and to distribute them by development to each
organ or texture after its kind;" second, the origin of
such centres or nuclei from previously existing nu-
clei. In this short paper of three pages, are con-
tained, as stated, the essentials of the cell doctrine
of Virchow, and as it has recently assumed addi-
tional interest on controversial* grounds, it may be
well to introduce as much as bears directly upon the
subject. "The centre of nutrition with which we
are most familiar, is that from which the whole or-
ganism derives its origin — the germinal spot of the
ovum. From this, all the other centres are derived,
either mediately or immediately; and in directions,
numbers, and arrangements, which induce the con-
figuration and structure of the being. As the entire
organism is formed at first, not by simultaneous
formation of its parts, but by the successive devel-
opment of these from one centre, so the various parts
arise each from its own centre, this being the orig-
inal source of all the centres with which the part is
ultimately supplied.

"From this it follows, not only that the entire
organism, as has been stated by the authors of the
cellular theory, consists of simple or developed cells,
each having a peculiar independent vitality, but
that there is in addition, a division of the ichole into
departments, each containing a certain number of
developed cells, all of lohich hold certain relations,

* Edinburgh Monthly Medical Journal, Feb. and April, 1869,
pp. 766 and 959.

THE CELL DOCTRINE. 47

to one central or capital cell, around which they are
grouped. It would appear that from this central cell,
all the other cells of its department derive their
origin. It is the mother of all those within its own
territory. It has absorbed materials of nourishment
for them while in a state of development, and has
either passed them off after they have been fully
formed, or have arrived at a stage of growth when
they can be developed by their own powers.

"Centres of nutrition are of two kinds, — those
which are peculiar to the textures, and those which
belong to the organs. The nutritive centres of the
textures are in general permanent. Those of the
organs are in most instances peculiar to their em-
bryonic stage, and either disappear ultimately or
break up into the various centres of the textures of
which the organs are composed.

" A nutritive centre, anatomically considered, is merely
a cell, the nucleus of lohich is the permanent source of suc-
cessive broods of young cells, which from time to time
fill the cavity of their parent, pass off in certain
directions, and under various forms, according to
the texture or organ of which their parent forms a
part."

Prof. Goodsir does not fail to state in the first para-
graph of his paper, that with many of these centres
anatomists have been for some time familiar, but
further remarks that with few exceptions they have
looked upon them as embryonic structures. He
alludes in a note to the observations of Bowman
and Barry, the former on "Muscle," and the latter
" On the Corpuscles of the Blood," in Philosophical

48 THE CELL DOCTRINE.

Transactions, respectively, of 1840 and 1841, and
states in a second note that "for the first consistent
account of the development of cells from a parent
centre, and more especially the appearance of new
centres within the original sphere, we are indebted
to Martin Barry."* We have carefully read the
references in each instance. In Bowman's paperf
we can recognize a brief reference to a possible
influence of the cell upon nutrition, but none as to
its origin, in the following sentence: "It is, how-
ever, not impossible, that in all these cases, there may
be during development, and subsequently, a further
and successive deposit of corpuscles (nuclei) from
which both growth and nutrition may take their
source." That Dr. Barry's paper is more explicit
has been shown.

HUXLEY, 1853.|

Allusion has already been ^made to Prof Huxley

* Goodsir, Anatomical Memoirs, vol. ii, p. 389, and note on
pp. 390-91.

f Bowman, "Muscle," Philos. Transac, 1840, pt. i, p. 485.

I We presume it will scarcely be inferred by any reader, that
the views of Prof. Huxley here presented are brought forward as
those now entertained by the learned Professor, and with which
the public have been made so generally familiar through his lec-
tureon " Protoplasm," or the *' Physical Basis of Life," delivered
at Edinburgh, November 18th, 1868, and originally published in
the "Fortnightly Keview " for February, 1869; but also largely
republished in numerous English and American periodicals, as
well as in a separate pamphlet, to be had of the publishers of the
Yale College Courant, New Haven, Conn. To one closely observ-
ing, however, we think that these later views will appear to be
foreshadowed in the theory here given, and which we think of
suflBcient historical importance to justify its presentation here.

THE CELL DOCTRINE. 49

in connection with Wolff, of whose theory he has
been the able exponent. In the same paper* he
has given us his own views — " conceived in the spirit,
and not unfrequently borrowing the phraseology, ot
Wolff and Yon Baer." We present them, as far as
may be consistent with brevity, in his own w^ords:

"Vitality, the faculty, that is, of exhibiting defi-
nite cycles of change in form and composition, is a
property inherent in certain kinds of matter. There
is a condition of all kinds of living matter in which
it is an amorphous germ — that is, in which its exter-
nal form depends merely on ordinary physical laws,
and in which it possesses no internal structure.
Now, according to the nature of certain previous
conditions, the character of the changes undergone,
or the different states exhibited — or, in other words,
the successive differentiations of the amorphous mass
will be different.

" The morphological differentiation may be of two
kinds. In the lowest animals and plants, — the so-
called unicellular organisms — it may be said to be
external, the changes of form being essentially con-
filled to the outward shape of the germ, and being
unaccompanied by the development of any internal
structure.

"But in all other animals and plants, an internal
morphological differentiation precedes or accompa-
nies the external, and the homogeneous germ becomes
separated into a certain central portion, which we
have called the endoj^last, and a peripheral portion,

* Huxley, Keview of the Cell Theory. Br. and For. Med.-Chir.
Rev., Oct., 1853, p. 305.

50 THE CELL DOCTRINE.

the periplast. Inasmuch as the separate existence of
the former necessarily implies a cavity in which it
lies, the germ in this state constitutes a vesicle with
a central particle, or a 'nucleated cell.' There is no
evidence ivhaiever that the molecular forces of the liv-
ing matter (the *vis essentialis' of Wolf, or the
vital forces of the moderns), are by this act of differ-
entiation localized in the endoplast to the exclusion
of the periplast, or vice versa. Neither is there any
evidence that any attraction or other influence is exercised
by the one over the other; the changes which each sub-
sequently undergoes, though they are in harmony,
having no causal connection with one another, but each
proceeding, as it would seem, in accordance with the
general determining laws of the organism. On the
other hand, the *vis essentialis' appears to have es-
sentially different and independent ends in view, in
thus separating the endoplast from the periplast.

"The endoplast grows and divides; but, except in
a few^ more or less doubtful cases, it would seem to
undergo no other morphological change. It fre-
quently disappears altogether; but as a rule it under-
goes neither chemical nor morphological metamor-
phosis. So far from being the centre of activity of
the vital actions, it would appear much rather to be
the less important histological element.

^' The periplast, on the other hand, which has hith-
erto passed under the name of cell wall, contents
and intercellular substance, is the subject of all the
most important metamorphic processes, whether
morphological or chemical, in the animal and plant.
By its differentiation, every variety of tissue is pro-

THE CELL DOCTRINE. 51

duced; and this difterentiation is the result, not of
any metabolic action of the endoplast, which has fre-
quently disappeared before the metamorphosis begins,
but the intimate molecular changes in its substance,
which take place under the guidance of the 'vis
essentialis,' or, to use a strictly positive phrase, occur
in a definite order, we know not why.

" The metamorphoses of the periplastic substance
are twofold — chemical and structuraL The former
(chemical), may be of the nature either of conversion, —
change of cellulose into xylogen, intercellular sub-
stance, &c., of the indifferent tissues of embryos into
collagen, chondrin, &c., — or of deposit, — as of silica
in plants, of calcareous salts in animals. The struc-
tural metamorphoses, again, are of two kinds, vacuola-
Hon or the formation of cavities, as in the intercellu-
lar passages of plants, the first vascular canals of
animals — and fibrillaiion, or the development of a
tendency to break up in certain definite lines rather
than in others."

These views he illustrates by examples from vege-
table life in the sphagnum leaf, and from animal life
in connective tissue and striped muscle.

As characteristic and distinguishing features of
this theory, we desire to point out, first, the substitu-
tion of the term ^^ endoplast" for "nucleus;" that
of ^'periplast'' for "cell wall," and "intercellular,"
"substance." Second, the absolutely passive na-
ture of the "endoplast," which is neither itself the
author of changes, nor the subject of changes.
Third, the passive nature as well, of the " periplast,"
so far as it is the author of changes, though it is pre-

52 THE CELL DOCTRINE.

eminently the subject of changes, the seat in which
changes take place. And herein, we believe Huxle}^
to have been misinterpreted by some who have
presented his views elsewhere, as Dr. Beale,* who
represents him as believing the periplast active, that
it is the efficient agent, that it sends in partitions,
&c. But that Prof. Huxley considered it passive we
believe may be legitimately inferred from his text.
As the seat of change, however, accomplished not as
"the result of any metabolic action of the endoplast,
but of intimate molecular changes in its substance,
which take place under the guidance of the vis es-
sentialis,'' the periplast is differentiated into every
variety of tissue. Finally, we have the distinct ad-
mission, as seen in the sentence last quoted, and also
throughout the entire expression of the theory, of a
controlling, guiding principle, through which the
differentiation is accomplished. This principle,
which is here referred to as the " vis essentialis," is
elsewhere included under the expressions " vitality,"
and "general determining laws of the organism."
Though this admission is seemingly so at variance
with the views of the same observer at the present
date (1870), who in common with other physicists
emphatically denies the existence of "vital force,"
or even such a thing as life itself, yet, as already
intimated, we deem it possible to detect a fore-
shadowing of his more modern views, in the follow-

* Beale, Microscope in Medicine. Third Edition. London :
1867, page 147. Beale, Structure and Growth of the Tissues.
London : 1865, pp. 9, 10.

THE CELL DOCTRINE. 63

ing paragraph of the paper whence we have derived
our information :

" We have therefore maintained the broad doctrine
established by Wolff, that the vital phenomena are
not necessarily preceded by organization, nor are in
any way the result or effect of formed parts, but that
the faculty of manifesting them resides in the matter
of which living bodies are composed, as such — or,
to use the language of the day, that the vital forces
are molecular forces J^"^

Huxley moreover says that the three botanical
data upon which Schwann's theory was based, viz. :

1. The anatomical independence of the vegetable
cell as a separate entity,

2. His conception of the structure of the vegeta-
ble cell, and

3. Its mode of development, were all erroneous.
Since first, he (Huxley) considers that the fact that

by certain chemical or mechanical means, a plant
may be broken up into vesicles, corresponding w^ith
the cavities which previously existed in it, is of no
more value in proving the independence of these
vesicles, than the fact that a rhombohedron of spar,
broken up with the hammer, into minute rhombo-
hedrons, is evidence that those minuter ones were
once independent, and formed the larger by their
coalescence.

Second, Schwann's view of the anatomy of the
cell was incorrect, since he regarded the nucleus as
invariably present, whereas in certain vegetable cells

* Huxley, loc. citat., p. 314.
5*

64 THE CELL DOCTRINE.

(as in Hjdrodictyon, Yaucheria, Caulerpa, Sphag-
num), it is indubitably absent; and since he did not
include the nitrogenous primordial utricle, discov-
ered by Mohl, in 1844,* as one of the elements of
the cell.

Finally, Schwann's mode of cell-development is
erroneous, having " been long since set aside by the
common consent of all observers;" cell-development
always occurring by division, except in the embryo
sac of the Phanerogamia, the sporangia of Lichens,
and of some Algse and Fungi ; and even the free
cell-development of the latter is quite diiferent from
that of Schleiden and Schwann, being by the devel-
opment of a cellulose membrane (periplast) around
a mass of nitrogenous substance (endoplast), which
may or may not contain a nucleus.

The diiference between the views of Schwann and
Huxley are best expressed by the latter in the con-
trast he draws between those of Schwann and Wolf:
"For Schwann, the organism is a beehive, its action
and forces resulting from the separate but harmoni-
ous action of all its parts. For Wolff' (and Huxley),
it is a mosaic, every portion of which expresses only
the conditions under which the formative power
acted, and the tendencies by which it was guided."

The statements of Prof. Huxley with regard to
cell-development entirely accord with the most recent
observations on the subject, and are quite important
to us in tracing out the present state of the cell doc-
trine.

* The existence of the primordial utricle is denied by many
botanists of the present day.

THE CELL DOCTRINE. 66

J. hughes' BENNETT, 1866.*

Dr. Bennett, of Edinburgh, considers that "the
ultimate parts of organization are not cells nor
nuclei, but the minute molecules from which these
are formed. They possess independent physical and
vital properties, which enable them to unite and
arrange themselves so as to produce higher forms.
Among these are nuclei, cells, fibres, and membranes,
all of which may be produced directly from mole-
cules. The development and growth of organic
tissues is owing to the successive formation of his-
togenetic and histolytic molecules. The breaking
down of one substance is often the necessary step to
the formation of another; so that the histolytic or
disintegrative molecules of one period become the
histogenetic or formative molecules of another."

Again : " As to development, the molecular is the
basis of all the tissues. The first step in the process
of organic formation is the production of an organic
fluid ; the second, the precipitation in it of organic
molecules, from which, according to the molecular
law of growth, all other textures are derived either
directly or indirectly. "f

* Bennett's Practice of Medicine. Am. Ed. of Wm. Wood &
Co.,N. Y.: 1866, p. 118.

Prof. Bennett has further elaborated his views in the Edinburgh
Medical Journal, March, 1868, and The Popular Science Review,
January, 1869, but his conclusions are substantially the same as
quoted.

t Op. citat., p. 119.

56

THE CELL DOCTRINE.

Figs. 4, 5, 6, 7, illustrate these views amply.

Fig. 4. Fig. 5.

Fig. 6.

Fig. 7.

Fig. 4, Molecular structure of the scum on its first appearance, in a
clear animal infusion. Fig, 5, Molecular structure of the same six hours
afterwards. The molecules are separated, and the long ones (so-called
vibriones) in active movement. Fig. 6, The same on the second day.
Fig. 7, Filaments (so-called spirilla) formed by aggregation of the mole-
cules, in the same scum on the third and fourth days, all in rapid motion.
800 diam. linear. (From Bennett's Practice.)

Prof. Bennett contends, also, that morbid growths
may easily be shown to originate in a molecular
blastema, though not to the exclusion of pre-existing
cells. The accompanying figures are sufficiently ex-
planatory.

Fig. 8

Fig. 10.

Fig. 11.

Fig. 8, Nuclei imbedded in a molecular blastema. Fig. 9, Young fibre-
cells formed by the aggregation of molecules around the nuclei of Fig. 8.
Fig. 10, Cancer cells, one with a double nucleus. Fig. 11, Histolytic or
so-called granule-cells, breaking down from fatty degeneration. 250 diam.
linear. (From Bennett's Practice.)

It should be stated also, that this author in com-
mon with others not accepting the cell doctrine in
its entirety, admits the production of cells by buds,
division, or proliferation, without a new act of gene-
ration, and that " this fact comprehends most of the

THE CELL DOCTRINE. 57

admitted observations having reference to the cell
doctrine."*

We have in the expression of this theory, a prac-
tical admission of the spontaneous origin of ani-
mal life, of which Dr. Bennett, in the paper re-
ferred to in the Popular Science Review, for Jan.,
1869, openly declares himself the advocate.

Closely allied to this theory is the so-called in-
vestment or cluster-theory (Umhlillungs-theorie), de-
scribed by Yirchow on page 53, of Cellular Pathology,
(Am. Ed. of Chance's Translation); according to which
"originally a number of elementary globules existed
scattered throughout a fluid, but that under certain
circumstances they gathered together, not in the
form of vesicular membranes, but so as to constitute
a compact heap, a globe (mass, cluster — KlUmpchen),
and that this globe was the starting-point of all fur-
ther development, a membrane being formed outside
and a nucleus inside, by the differentiation of the
mass, by apposition, or intussusception."

Fig. 12.

Fig. 12. Diagram of the Investment (cluster) theory. «, Separate
elementary granules, h, Heap of granules (cluster), c, Granule cell,
with membrane and nucleus.

TODD AND BOWMAN, 1856.

Notwithstanding earlier approximations to the

* Op. citat., p. 123.

68 THE CELL DOCTRINE.

truth, we find free cell formation still admitted by the
eminent authorities Todd and Bowman, as one mode
of origin of cells, so late as December, 1856, though
the spontaneous origin of organs is spoken of as ex-
ceedingly doubtful. After describing the elements
of the ovum, considered in its entirety as a nucleated
cell, and referring to the period after fecundation, it
is stated, " At this period the embryo consists of an
aggregate of cells, and its further growth takes place
by the development of new ones. This may be ac-
complished in two ways; first, by the development
of new cells within the old, through the subdivision
of the nucleus into two or more segments, and the
formation of a cell around eaoh, which then becomes
the nucleus of a new cell, and may in its turn be the
parent of other nuclei ; and, secondly, by the forma-
tion of a granular deposit between the cells, in
which the development of the new cells takes place.
The granules cohere to each other in sejyarate groups^ here
and there J to form nuclei, and around each of these a deli-
cate membrane is formed^ which is the cell membrane.
The nuclei have been named cgtoblasts, because they
appear to form the cells; and the granular deposit in
which these changes take place is called the cytoblas-
tema.

"In every part of the embryo the formation of
nuclei and of cells goes on in one or both of the
ways above mentioned, and, by and by, ulterior
changes take place, for the production of the ele-
mentary parts of the tissues."*

* Todd and Bowman, The Physiological Anatomy and Phj'siol-
ogy of Man. Am. Edit., Philadelphia: 1857, p. 63.

THE CELL DOCTRINE. 59

Thus did physiologists adhere to the original free
cell formation of Schleiden and Schwann. Singu-
larly, Dr. Carpenter,* who expressly states, in his
Manual of Physiology, edition of 1865, that he has
been led to the view of Professor Beale by com-
parison of the results of the recent inquiries of sev-
eral British and Continental histologists with those
of his own studies, says, a few pages further on (p.
150), "]^ew cells may originate in one of two prin-
cipal modes; either directly from a previously exist-
ing cell, or by an entirely new process in the midst
of an organizable blastema." He then proceeds to
give the two methods in detail, without in any way
denying the latter.

viRCHOW, 1858.

Less than two years later, August 20th, 1858, Prof.
Yirchow published his '* Cellular Pathology as based
upon Physiological and Pathological Histology."
According to him, the cell is the only possible start-
ing-point for all biological doctrines. This cell can
only originate from a previously existing cell, taking
its primary origin from the ovum, and the Harveian
maxim omne vivum ex ovo, becomes in its special
application, omnis cellula e celluld. This is true of all
physiological and pathological processes in the vege-
table and animal. In all editions of " Cellular
Pathology" which we have met, the typical cell is
described as consisting essentially of "cell wall,"

* Carpenter, Manual of Physiology, London : 1865. Note on
p. 14.

60 THE CELL DOCTRINE.

"cell contents," and "nucleusV the "nucleolus,"
though usually met in fully developed older forms,
is not considered an essential constituent of the
cell. The object of the " nucleus," according to *
Yirchow, is entirely connected with the life of the
cell, that which maintains it as an element and
which insures its reproduction. While to the "cell
co>utents" over and above the nucleus, that is the
" residual cell contents," is due the function of the
cell, that to which is due the contractility of mus-
cle, the neurility and sensation of nerve, and the
secretory office of the gland cell.*

To secure the universal application of the cell
doctrine, it becomes necessary to eliminate from the
vegetable cell, the external non-nitrogenous mem-
brane known as cellulose, and restrict it to the nitro-
genized portion comprised in the primordial utricle as
the proper cell wall, and in the protoplas7nic contents
of the cavity as the proper cell contents, which con-
tain also the nucleus. " It is only when we adhere
to this view of the matter, when we separate from
the cell all that has been added to it as an after-de-
velopment, that we obtain a simple, homogeneous,
extremely monotonous structure, recurring with ex-
traordinary frequency in living organisms."!

More recently, however, Virchow is reported as
not regarding the "cell wall" as an essential part of
the cell, as stated in Cellular Pathology; but that a

* Virchow, Cellular Pathology as based upon Physiological and
Pathological Histology. Second Edition. Translated by Frank
Chance, MB., «&c. Am. Edition, Philadelphia: 1863, p. 37.

t Op. cit., pp. 31, 34.

THE CELL DOCTRINE. 61

nucleus surrounded hy a molecular blastema was sufficient
to constitute a cell; then he says that the outer part of
this cell blastema consolidates and forms a cell wall
as Beale has shown, and that this takes place in the
amoeba when placed in water.*

As thus defined, the cell is the seat of pathologi-
cal and physiological processes rather than the blood,
or the nerves. The cell is active, — the ultimate mor-
phological element in which there is any manifesta-
tion of life, and beyond which the seat of real action
cannot be removed. Hence the term Cellular Pathol-
ogy rather than humoral, or neural, or solidistic. The
so-called exudations are not such in the strict sense of
the term, and the cells which they contain, whether
of pus or organizable lymph, are the result of pro-
liferation of previously existing cells. Even "fibrin,
wherever it occurs in the body external to the blood,
is not to be regarded as an excretion from the blood,
but as a local production," resulting from the activity
of the cells of the tissue in which it is found, and con-
veyed to the surface by the transudation oithQ serous
fiuids alone. t In the above statements we have the
first distinctive feature of Yirchow's theory.

Again, since every organized body is usually made
up of a number of these cells, each independent in
itself, yet combined and arranged for the attainment
of a special end, and therefore mutually dependent,
there result certain communities or cell territories
into w^hich the body is portioned out by Yirchow.

* Letter from Berlin, in Edinburgh Medical Journal, February,
1865.
f Virchow, op. cit., pp. 435-6.

6

62 THE CELL DOCTRINE.

But not only is the relation of these cells to each
other and to the central cell whence they took their
origin mutually dependent, but in many animal tis-
sues, at least, we have the so-called intercellidar sub-
stance in a certain definite manner dependent upon
the cell or cells which it surrounds, "so that certain
districts belong to one cell and certain others to
another." Especially is this the case in pathological
processes, where sharp boundaries may often be drawn
between cell territories. Herein have we the second
distinguishing character of Virchow's theory.

There are also a third and fourth distinctive fea-
tures. It has already been explained that the prin-
ciple of the theory of Schleiden and Schwann lay in
this, that every tissue, healthy or morbid, results
from the apposition of cells, and that this principle
is still observed as correct, the mode of origin of the
primary cell being alone the object of dispute. Ac-
cording to Virchow, however, it is a special cell
which becomes the starting-point of physiological
and pathological processes, and by its various meta-
morphoses constitutes the healthy or morbid tissue,
excepting epithelial formations. This cell is the
so-called connective tissue corpuscle, or cell of the con-
nective tissue, which, according to Virchow, is a cell
with all its essential constituents (cell wall, cell con-
tents, and nucleus), and not a nucleus alone, as orig-
inally described by Schwann, and later by Henle*
and Landois.f From the well-known universal

* Henle, Bericht uber die Fortschritte d. Physiol., 1859; 1866,
p. 41.
f Landois, Zeits. f. wiss. Zool., Bd. xvi, p. 1.

THE CELL DOCTRINE.

63

prevalence of connective tissue, this view receives
support. Thus, it is from the connective tissue
corpuscles of the soft, silk-like connective tissue, so
universally present in muscle, that the muscular fas-
ciculi are primarily developed. It is from these that
nerve fibres take their origin. It is by the rapid
proliferation of these corpuscles that pus is formed,

Fig. 13.

Fig. 13. Purulent granulation from the subcutaneous tissue of a rab-
bit, round about a ligature, a. Connective tissue corpuscles, b, Enlarge-
ment of the corpuscles with division of the nuclei, c, Division of the cells
(granulations), d, Development of the pus corpuscles. x300. (From

Virchow.)

Fig. 14.

Fig. 14. Interstitial purulent inflammation of muscle in a puerperal
woman, m m, Primitive muscular fibres, i i, Development of pus cor-
puscles by means of the proliferation of the corpuscles of the interstitial
connective tissue. x280. (From Virchow.)

64 THE CELL DOCTRINE.

(Figs. 13 and 14); it is from the perverted growth
and development of these that tubercle and cancer

Fig. 15.

Fig. 15. Development of cancer from connective tissue in carcinoma
of the breast, a, Connective tissue corpuscles, b, Division of the nuclei.
c, Division of the cells, d, Accumulation of the cel,ls in rows, e, Enlarge-
ment of the young cells and formation of the groups of cells (foci, Zellen-
heerde), which fill the alveoli of cancer. /, Further enlargement of cells
and groups, g, The same development seen in transverse section. (From
Virchow.)

arise (Fig. 15), and similarly all pathological new
formations. None of these products are exudations
from the blood, according to Virchow. They are
entirely local in their origin. In these views he is
supported by the majority of German observers.

Another mode of formation of pus is however ad-
mitted by Yirchow, in the growth and development
of new cells in epithelium, whether in cuticle or mu-
cous membranes. Whether forms of suppuration
exist which may be referred to muscular, nervous,
and capillary elements, he considers doubtful.

A fourth and final distinctive feature of Virchow's
views, concerning which there is less unanimity, even
among German histologists, is his peculiar system of

THE CELL DOCTRINE.

65

canals or tubes, produced by the anastomosis of one
cell with another, and which he considers must be
classed with the great canalicular system of the body,
as forming a supplement to the blood and lymphatic
vessels, and as filling up the vacancy left by the old
vasa serosa which do not exist.* (See Fig. 16.) Of

Fio. 16.

^^^

Fig. 16. Connective tissue from the embryo of a pig after long-contin-
ued boiling. Large spindle-shaped cells, connective tissue corpuscles
(Bindegewebesktirperchen), some isolated and some still imbedded in their
basis substance, and anastomosing one with the other. Large nuclei with
their membrane detached ; cell contents in some cases shrunken. x350.
(From Virchow.)

this system he also considers the cord-like fibres of
yellow elastic tissue as forming a part.f These he
considers, with Donders,t as originating by a trans-

* Virchow, op. citat., p. 76.
f Virchow, op. citat., p. 133, a. f.
X Bonders, Siebold und Kdlliker's Zeitschrift, Bd. iii.
6*

66 THE CELL DOCTRINE.

formation of the connective tissue corpuscles them-
selves. He says, " The transformation of these latter
into the former, can gradually be traced with such
distinctness, that there remains no doubt, that even
the coarser elastic fibres directly result from a chem-
ical change and condensation of the walls them-
selves.* Where originally there lay a cell, provided
with a delicate membrane and elongated processes,
there we see the membrane gradually increasing in
thickness and refracting the light more strongly,
whilst the proper cell contents continually decrease
and finally disappear.

Fig. 17.

Fig. 17. Elastic networks and fibres from the subcutaneous tissue of
the abdomen of a woman, a a, Large elastic bodies (cell bodies), with
numerous anastomosing processes, b b, Dense elastic bands of fibres on
the border of larger meshes, c c, Moderately thick fibres spirally coiled
up at the end. dd, Finer elastic fibres, at e with more minute spiral coils.
x300. (From Virchow.)

" The whole structure becomes in this way more

* Virchow, op. citat., p. 133,

THE CELL DOCTRINE. 67

homogeneous, and to a certain extent sclerotic, and
acquires an incredible power of resisting the influ-
ence of reagents, so that it is only after long-contin-
ued action that even the strongest caustic substances
are able to destroy it, whilst it completely resists the
caustic alkalies and acids in the degree of concentra-
tion usually employed in microscopical investigation.
The farther this change advances, the more does the
elasticity of the parts increase, and in sections we
usually find these fibres, not straight or elongated,
but tortuous, curled up, spirally coiled, or forming
little zigzags (Fig. 17, c, e). These are the elements
which by virtue of their great elasticity, cause retrac-
tion in those parts in which they are found in con-
siderable quantity, as, for example, in the arteries.
The fine elastic fibres, which are those which possess
the greatest extensibility, are usually distinguished
from the broader ones, which certainly do not pre-
sent themselves in tortuous forms. As regards their
origin, however, there seems to be no diflference be-
tween the two kinds; both are derived from the
connective tissue cells, and their subsequent arrange-
ment is only a reproduction of the original plan.
In the place of a tissue, consisting of a basis sub-
stance and anastomosing reticulated cells, there
afterward arises a tissue with its basis substance
mapped out by long elastic networks with extremely
compact and tough fibres." This may be looked
upon as the least well-determined of the important
points of Virchow's doctrine, though most German
histologists also favor it. Among these may be

68 THE CELL DOCTRINE.

classed Kolliker,* C. Q. Weber,t Leydig,t Fried-
reich,§ His,|| Donders,! Wittich,** Bottcher,tt Bill-
roth,! J and Strieker. They are opposed by Schwann,
Reichert, and Henle, and find little favor among
English and American histologists.

A part of this system, also, according to Virchow,
are the so-called dentinal tubules, the lacunae and
canaliculi of bone, even the continuity traced by
Gerlach,§§ between the ciliated cells of the aqueduct
of Fallopius; that by Heidenhain|||| and BriickeTf^f
between the lacteals and cylinder epithelium of the
intestinal villi of the rabbit, by means of corpuscles
of connective tissue; in the epithelium of the endo-
cardium by Luschka;*** and the results of similar
observations by Eckhart,ttt Billroth, J JJ and Fried-
reich. §§§

* Kolliker, Manual of Human Microscopic Anatomy, p. 41.
1860. Also recent paper in which he completely assents to Vir-
chow's views, according to N. Y. Q. J. Pschy. Med., July 1869.
f Weber, C. O., Virchow's Archiv, Bnd. xiii-xv.
J Leydig, Handbuch der Histologic. 1856.
§ Friedreich, Virchow's Archiv, Bd. xv.
II His, Beitrage zur Normalen in Pathol. Histol. d. Cornea.
^ Bonders, loc. citat.
** Wittich, Virchow's Archiv, Bd. ix.
ff Bottcher, Virchow's Archiv, Bd. xiii.

J J Billroth, in Beitrage zur Pathol. Histol., 1858, admits all but
the tubular nature of the processes.
g§ Gerlach, Mikrosk. Studien. 1858.

nil Heidenhain,Moleschott's Untersuchungen,Bd. iv, 1858,p. 251.
^^ Briicke, Moleschott's Untersuchungen, Bd. viii, 1862, p. 495.
*** Luschka, Virchow's Archiv, Bd. ix, p. 569.
Iff Eckhart, Beitrage Anat. und Physiol. 1855.
Ill Billroth, Mailer's Archiv, 1858.
§g§ Friedreich, loc. citat., p. 538.

THE CELL DOCTRINE. 69

The other fibrous element of areolar or connec-
tive tissue, which forms the mass of its bulk, the
pure white fibrous or waving, does not, according to
Virchow, have its origin in cells, but is a modifica-
tion of a previously homogeneous intercellular sub-
stance, deposited between the cells, — a view which
in its glaring departure from the primary proposition
that the cell is the starting-point, and that every
tissue is composed of cells or some modification ot
cell forms, presents one of the few inconsistencies
traceable in the theory of Virchow.

We think it proper, in a historical memoir of this
kind, to refer to some severe critical remarks which
appeared in the Edinburgh Medical Journal of Feb-
ruarj^ and April, 1869, in which Prof. Yirchow is ac-
cused of appropriating the observations of Prof. Good-
sir as his own. That there are points in common,
it will be recollected, and, also, that these are first,
the invariable origin of cells from previously existing
cells, and second, the division of the tissues into cell
territories. E'ow on the one hand we deem that the
dedication of Yirchow's volume to Prof. Goodsir is
as handsome an accredit as could possibly be given
for whatever of common there may be in the writings
of the two authors, and on the other hand we have
seen that Martin Barry is acknowledged even by
Goodsir, to be the author of the " first consistent
account of the development of cells from a parent
centre." The idea of cell territories seems, however,
to have originated with Goodsir, nor do we believe,
for the reason stated, that Virchow intended to usurp
his prerogative. The merit of Virchow consists in

70 THE CELL DOCTRINE.

his application by actual demonstration of the first
of these points to so large a variety of physiological
and pathological processes, to which is added original
conception in the prominence given to the connec-
tive tissue corpuscle and the canalicular system,
whatever may be the truth with regard to either.

SARCODE OF DUJARDIN. PROTOPLASM OF MAX SCHULTZE.

1835-61.

Dujardin* had, in 1835, discovered in the lower ani-
mals a living, moving, contractile substance, which
he called sarcode. The peculiar appearances of this
substance attracted the attention of many observers,
among whom were Meyen,f Huxley, Max Schultze,
John Muller, and others, who thought it peculiar to
the lower animals, and there was assigned to it a
property of " irritability without nerves."|

The observation of Siebold,§ that the yolk glob-
ules of Planaria exhibit contractions and expansions,
which with suitable care continue for hours, and the
discoveries which followed of similar movements
and changes in form, led Kolliker|| to express the
conjecture that the contents of all cells are contractile.
Virchowf attributed the movements to a contractile

* Dujardin, Ann. d. Sciences Nat., torn, iii et v.
f Meyen, Einschlagige Liter, in E. Iljeckel's Die Kadiolaren.
1862.

J Schultze, Max, Organis. d. Polythalamien. 1854.
§ Siebold, Froriep's Notizen, Nr. 380, p. 85.
II Kolliker, Wurzb. Verh., Bd. viii.
5[ Virchow, Archiv, Band v.

THE CELL DOCTRINE. 71

substance. Leyclig* considered the movements of
the yolk globules as phenomena of life, and Kuhnef
had studied physiologically and chemically, sarcode
and muscular tissue, and compared the irritability
and changes after death, of both. But all consid-
ered sarcode as something different from the ani-
mal cell, as a body sui generis. Max Schultze, in
1861,1 had first shown this analogy between sarcode
and the contents of the animal cell, and that the en-
tire infusorial world, simple or compound, is made
up of cells, thus extending the typical formative
element of Schwann to the entire organized creation.
So much for the relation of sarcode to the animal
cell.

The comparison between sarcode and the proto-
plasm of plants was undertaken by Unger,§ E.
Brucke,|| E. Hseckel.t Max Schultze,** and W.
Kuhne,tt and by their efforts, according to Strick-
er,|| our knowledge of the independent life of the
cell was extended, in a very short space of time, fur-
ther than in the twenty years previous.

Unger§§ (1855), had been struck with the close

* Leydig, Handbuch der Histologie. 1856.
f Kuhne, Mull. Archiv., 1859, p. 817.
X Schultze, Max, Mull. Archiv, 1861, p. 17.
^ Unger, Anatomie und Ph3^siology d. Pflanzen. 1855.
II Briicke, E., Elementarorganism, Wien Sitzungsb. 1861.
TJ Hteckle, E., Radiolaren. 1862.
** Schultze, Max, Protoplasm der Rhizopoden und der Pflanz-
enzellen. 1863.
fl Kuhne, W., Protoplasm und die Contractilitat. Lpzg.: 1864.
XI Strieker, S., Handbuch der Lehre von den Geweben des
Menschen undder Thiere. Leipzig: 1868, p. 3.
gg Unger, op. citat, p. 280.

72 THE CELL DOCTRINE.

similarity of the mobile phenomena of the Poljtha-
lamise with those of the processes of protoplasm
stretched across the cavity of many vegetable cells.
Although he had not personally investigated the
former, he became convinced from Schultze's de-
scription, that a resemblance amounting to identity
existed between their movements and the protoplasm
streams of vegetable cells."*

Shortly before this, Pringsheimf (1854), showed
that no such membrane as a primordial utricle ex-
isted, but that all within the cellulose wall of the liv-
ing vegetable cell was protoplasm and cell fluid, how-
ever complex its composition.

"He admitted that in the cortical layer of the pro-
toplasma a distinct arrangement into layers often
occurred, and these he distinguished as the cutane-
ous and granular layers of the protoplasma, but he
denied that the primordial utricle could be difteren-
tiated as a membrane from the subjacent protoplasm.
If, in animal cells, partly from their relatively small
size, and partly from their greater average wealth in
protoplasma, it is more rarely possible to make a
sharp demarcation between a cortical layer of pro-
toplasm and a cell fluid, there nevertheless exists a
difference in the constitution of the former, such
that a cutaneous layer, destitute of, or scantily sup-
plied with granules, incloses the remaining more
granular material. The white blood-cell may serve

* DuflSn, A. B., On Protoplasm. Quart. Jour. Mic. Sci., N. S.,
vol. iii, 1863, p. 252.

■)- Pringsheim, Untersuchungen iiber d. Bau. u. d. Bildung d.
Pflanzenzelle. 1854.

THE CELL DOCTRINE. 73

as an example. This is, however, very different from
a proper membrane."*

The name protoplasm for the contents of the ani-
mal cell had already been brought into use by
Kemak.

Leydig,t iu 1856, claimed for the contents of the
cell a higher dignity than for the membrane or
cell wall. He claimed that a cell was but protoplasm
(klumpchen-substanz) inclosing a nucleus. The cell
membrane, according to him, was simply the hard-
ened periphery of the substance of the cell.

To Max Schultze, however, belongs the credit of
having fully overturned the vesicular idea of cells.
In 1861,t he insisted upon some modification of pre-
vailing views, respecting the relation of cell wall to
cell contents, and contended for a higher position
for that part of the cell corresponding to the pro-
toplasm of Von Mohl (that within the so-called
primordial utricle), and showed how a careful study
of the phenomena, presented by the pseudopodia
extended b}^ the various Rhizopods, might aid in
clearing up the life of the elements of the cell.

He also defined the cell as ''protoplasm surround-
ing a nucleus.' ' The importance of this definition,
as stated by Stricker,§ lay not so much in the fact
that many cells were denied a cell wall, as that the so-
called cell contents could now be made to harmonize

* Duffin, loc. citat., p. 252.
f Leydig, op. citat.

X Schultze, Max, Ueber Muskelkorperchen, in Reichert and Du-
bois Reymond's Archiv, 1861.
§ Strieker, op. citat., p. 5.

7

74 THE CELL DOCTRINE.

with the animal primordial substance or sarcode.
Schultze illustrates his definition by the embryo cells
resulting from the segmentation of the ovum, as
typical cells, which are thus composed of protoplasm
surrounding a nucleus, which nucleus, as well as pro-
toplasm, are products of like constituent parts of
another similar cell. " The cell leads in itself an
independent life of which the protoplasm is espe-
cially the seat, although to the nucleus also undoubt-
edly falls a most important, though not yet precisely
determined role. Protoplasm is for the most part no
further distinct than that it will not commingle with
the surrounding medium, and in the peculiarity that
with the nucleus it forms a unit. Upon the surface
of the protoplasm, there may form a membrane,
which, although derived from it, may be chemically differ-
ent, and the assertion that it is the beginning of a retro-
gression may be defended, A cell with a membrane can
not divide itself, unless the protoplasm within the
membrane divides itself. A cell within a membrane
chemically different from protoplasm, is like an en-
cysted infusorium."*

Bruckef went even further in his definition, and
said that it was not shown that the nucleus even is
an essential element of the cell. In proof of which
he adduces the cells of cryptogams. Facts in justi-
fication of Brucke's doubt are adduced by StrickerJ
in the discovery by Max Schultze,§ in the Adriatic

* Schultze, Max, Protopl. d. Khizopoden. Leipzig: 1863.
•}- Briicke, E., Die Elementarorganismen, p. 18-22, 1861.
% Strieker, op. citat., p. 6.
§ Schultze, Max, Organis. d. Polythalam. 1854.

' THE CELL DOCTRINE. 75

Sea, of a non-nucleated amoeba, by Hseckel* in the
Mediterranean, of a non-nucleated protozoon (Pro-
togenes primordialis), and'by Cienkowskyf of two
non-nucleated monads, namely, Monas amyli and
Protomonas amyli. Hseckel says of his Protogenes
primordialis that it multiplies by division. Strieker's J
own observations on the fecundated egg of the frog,
incline him to adopt the view of Briicke, and to omit
the nucleus in a theory of elementary organization. §
With these general considerations in the history
of " protoplasm," we are the better prepared to take
up the theory of

DR. BEALE, 1861.

In April and May, 1861, Prof. Lionel S. Beale
delivered the lectures before the Royal College of
Physicians, of London, in which he promulgated

* Hseckel, Zeitschr. f. w. Zoolog., 1865, Bd. xv.

f Cienkowsky, Max Schultze's Archiv, 1865.

J Strieker, op. citat.

§ In a recent paper by Prof. Hseckel,! he states that the "pro-
toplasm theory" was brought forward in its elementary form by
Cohn,2 in 1850, and by Unger, in 1853, It was further developed
in 1858, and finally completely established in 1860, by Max Schultze.
Hseckel also considers that by no phenomena is the correctness of
this theory so thoroughly proved, and at the same time in so sim-
ple and unassailable a manner, as by the vital phenomena of the
Monera, by the processes of their nourishment and reproduction,
sensitiveness and motion, which entirely proceed from one and the
same very simple substance, a true "primitive slime."

1 Ilaeckel, Ernst, Monograph on the Monera, and Remarks on the Pro-
toplasm Theory. Q. Jour. Mic. Sci., Apr., July, and Oct., 1869.

2 Cohn, F., Nachtrage zur Naturgeschichte des Protococcus pluvialis ;
Nova Acta Ac. Leop. Carol., vol. xxii, pars ii, p. 605. 1850.

76 THE CELL DOCTRINE.

the views which have since been further elaborated
and become permanently associated with his name.
These views were published, in part, in Beale's
"Archives of Medicine," and in September, 1861,
in a volume " On the Structure of the Simple Tis-
sues of the Human Body," in the preface to which
he says " he thinks it right to state that the conclu-
sions which have now assumed a definite form have
gradually grown upon him during the course of ob-
servations, extending over a period of several years.
In fact some of the drawings in this volume, and
others wdiich have been published elsewhere, equally
favorable to this view, were made long before any
specific theory had been arrived at."

The "ce?^," or ^'elementary fart^^ as Dr. Beale pre-
fers to call it, is composed of matter in two states,
matter which \% forming^ and matter which is formed;
matter which has the power of groioing by producing
matter like itself out of pabuhmi or food, and matter
which possesses no such power, but results from the
death of the forming matter. The former is known
as germinal or living matter, the latter as formed mat-
ter. The former, in varying quantity in diflerent
cells, is central in its situation (see Plate, Fig. 17),
and includes what has been called by others nucleus,
cell contents, protoplasm, endoplast. The latter, also
present in difterent quantity in diflferent cells, is pe-
ripheral (Plate, Fig. 17), and includes what is known
as cell wall, periplast, intepcelldlar substance, and
products of secretion.

In its structural characters, germinal matter is soft,
transparent, colorless, and as far as can be determined

THE CELL DOCTRINE. 77

by the highest powers, structureless, being visible only
through its difference in refracting power as com-
pared with the menstruum in which it floats, or by
the granular matter it may entangle; and these
characters are the same at every period of its exist-
ence. They may be studied in the simplest vegetables,
in the thallus of the sugar fungus, among the low^est
animals, in the amoeba (Plate, Fig. 16), and in higher
animals in the mucous, pus, or white blood corpus-
cles (Plate, Fig. 10), all of which are composed almost
purely of germinal matter ; the very thin periphery
of formed material being scarcely appreciable or dis-
tinguishable from the diffraction band.

In its endowments and properties, germinal matter
is actingy living, groiving, and moving, through some
inherent power of its own. It alone, as stated, is
capable of producing material like itself out of pab-
ulum, and multiplying by division, or a dropping oft
of a portion of itself, which portion immediately
assumes an independent existence, and grows, main-
tains, and reproduces itself like the parent germinal
matter. It is also capable of being stained by an
ammoniacal solution of carmine, and the younger it
is, or more recently formed, the deeper is the stain it
assumes. And since the latest formed always ap-
pears in the centre of the mass, successive tints, or
zones of color, will often be produced in the staining
process, growing deeper from without inward, as
seen in Fig. 17 of Plate.

It has been stated that what is called nucleus by
Virchow and others, is included in germinal matter.
This is true, though the nucleus is not always the

7*

78 THE CELL DOCTRINE.

whole of the germinal matter. There maybe other
older germinal matter beyond the nucleus, on its
way to conversion into formed material, but still
germinal matter, which assumes a tint with carmine,
but not so deep as the nucleus. Thus, the entire
mass of the pus corpuscle (Plate, Fig. 10), except its
extreme periphery, is germinal matter, yet there is
within this another younger portion of germinal
matter, taking a deeper tint with carmine, but which
alone of the elements of this cell, we are in the habit
of calling " nucleus." The " nucleus^'' then, is noth-
ing but a new centre of germinal matter, and the
^' nucleolus ^^ is a younger centre. And there may
even be within this, a still younger portion of living
matter, taking even a deeper stain, which might be
called a ^'micleoleolusJ^ By this staining process may
we distinguish the nucleolus from a minute oil-drop
often mistaken for it, and which will not assume any
tint.

On the other hand, germinal matter in a compar-
atively quiescent state is often quite destitute of
nuclei. But let the mass be freely supplied with
nutrient matter and nuclei and nucleoli rapidly
make their appearance.

So with regard to the "cell contents" over and
above the nucleus, although they may all be germinal
matter, yet this is not necessarily the case. Thus in
the white blood corpuscle and mucous corpuscles,
what Yirchow would consider cell contents is all ger-
minal matter; but the superficial epithelial cell lining
the interior of the mouth has its nucleus alone com-
posed of germinal matter, and much that has been de-

THE CELL DOCTRINE. 79

scribed as cell contents is really formed matter. (Figs.
5 and 6 of Plate.) More nearly does the germinal mat-
ter of Beale* correspond with the "protoplasm" of
Max Schultze, with which, indeed, it seems identical,
except that the latter observer seems somewhat at a
loss how to dispose of the nucleus, of which he does
not speak as a new or young centre of protoplasm.

Formed material, instead of being aeiive, so far as
the vital acts described as characteristic of germinal
matter are concerned, i^jpassive, non-acting, dead, and
can only increase at the expense and death of the
germinal matter, on the periphery of which it is
formed. It differs widely in its appearance, and is
often "structured" as in muscle and nerve, but not
necessarily so, as is seen in the intercellular sub-
stance of hyaline cartilage. It possesses also cer-
tain properties, different in different situations, and
widely different also from those of germinal matter.
Thus it is contractile in the sarcous tissue of muscle,
exhibits neurility in the nerve, is protective in epi-
thelium, is diffluent as the formed material of the
milk-cell (milk), and in the formed material of the
liver-cell (bile). Again, it is hard and elastic in the
intercellular substance of cartilage, and epidermis,
horn and nails. It does not become stained on being
soaked in weak solution of carmine in ammonia, and
if by reason of the strength of the solution it should
happen to be stained, the color will w^ash out on
soaking in glycerine, which is not the case with the
coloring of the germinal matter.

* Beale, Protoplasm; or, Life, Force, and Matter. London:
1870, p. 38.

80 . THE CELL DOCTRINE.

The cause of this permanent staining of the ger-
minal matter by an ammoniacal solution of carmine,
is thought by Dr. Beale to be due to an acid reaction
of this matter, in consequence of which the carmine
is precipitated from its alkaline solution. This view
would seem to be confirmed by the researches of
Ranke on the Reaction of the Tissues.

The size of the elementary part, as thus composed,
is extremely various. The smallest particles of ger-
minal matter, measured by Dr. Beale, are less than
tuAtju ^f ^^ i^^<^^ i^^ diameter, and w^ould not be
called cells in the ordinary sense of the word, yet
they are functionally such ; that is, they grow, multi-
ply by division, and under appropriate circumstances
assume the characters of fully formed cells. On the
other hand, the largest epithelial cells, including
their germinal matter and formed material, are often
as large as the ^J^ of an inch in diameter, or larger;
cells of morbid growths are sometimes ^l^, while the
human ovum, which is a typical cell, varies from the
24U t^ T Ju of an inch. Pure germinal matter is rarely
seen in masses as large as the ^ J^ of an inch in di-
ameter, without breaking up into smaller particles of
germinal matter, and as constituting the nuclei of
fully formed cells, i^ usually from g^'^^ to -j^'^^ of an
inch in diameter.

The method of production of formed material is best
studied in the epithelial structures, particularly in
the epithelium lining mucous cavities, of which sec-
tions may be easily made down to the vessels whence
their nourishment is obtained. In the deep layers,
next the nutrient surface, the cells will be found to

THE CELL DOCTRINE. 81

consist of almost pure germinal matter (Plate, Fig.
1), imbedded in a soft, mucus-like, yet continuous
formed matter. These masses of germinal matter
divide and subdivide, pushing the older masses to-
wards the surface, to make up for those which are
constantly exfoliated. While this is going on, how-
ever, the germinal matter keeps increasing in size
until the cells arrive half way towards the surface, by
absorption of nutrient pabulum, which has to work
its way through any formed material already exist-
ing. At the same time, a portion of the germinal
matter is being converted into formed material,
which accumulates on its surface, within that already
formed, stretching it, and becoming more or less in-
corporated with it. Thus, both constituents of the cell
increase up to a certain point, the cells constantly growing
in consequence. As new cells are, however, produced
from below, the older ones are removed farther and
farther away, the formed matter becoming more and
more impervious to nutrient pabulum. At length a
point is attained when the entire cell ceases to in-
crease in size, since no pabulum reaches the masses
of germinal matter, though the latter is still being
converted into formed material. Hence, the masses
of germinal matter actually grow smaller, as the cell
increases in age; and when the periphery is reached,
there remains but a small nucleus of germinal matter,
with a large quantity of formed material. Thus, we
are enabled to judge of the age of the cell by the
relative quantity of germinal matter and formed ma-
terial ; if the former be large, and the latter small,
the cell is young, whereas, if the opposite relation

82 THE CELL DOCTRINE.

exists, the cell is old, and almost ready to exfoliate.
But exfoliation probably does not take place until
the last particle of germinal matter dies, and the en-
tire cell becomes a mass of passive, lifeless, formed
material.

The production of formed material from germinal
matter, may also be studied in the conversion of the
white blood-corpuscle into the red. In the spring of
the year, many white corpuscles can be found in the
blood of tbe frog and newt, undergoing conversion
into formed material at their edges, where the usual
granular appearance is being substituted by the
smooth and slightly colored. This goes on until all
except the nucleus is thus converted. In mammalia
this change goes on until the whole white corpuscle
is thus converted into the red.

Secondary Formed Material, — There are certain'
kinds of formed material, to which this term is ap-
plied by Dr. Beale. These are the oil of the fat cell
or vesicle, and the starch granule of the vegetable
cell. It results, as does all formed material, by a con-
version of the germinal matter into this special form.
The young fat cell, as all young cells, is almost pure
germinal matter; as it grows older, however, and is
exposed to oxidizing influences, the conversion of
germinal matter takes place, partly into the cell wall
proper of the fat vesicle, and partly into the second-
ary formed material or oil, until finally, it becomes a
mere dot on the inner surface of the cell-wall, or dis-
appears altogether.

The increase of cells, according to Beale, takes place
in several ways ; every cell coming from a pre-existing

THE CELL DOCTRINE. 83

cell, but the germinal matter is always the portion
in which it originates.

There is not generally a symmetrical division of
the nucleus into two, and these into four, as is so
often described, and as is often seen in the vegetable
cell, but. there is rather a budding, and subsequent
dropping ofi* of the portions of germinal matter
which is to produce the new cell, and which almost
always assumes the spherical form when allowed to
float freely. (See Figure 10 of Plate.) The formed
material is never active, but entirely passive in the
process of cell multiplication.

Nutriiion of Cells. — So, too, in the nutrition of the
cell, the germinal matter is the sole active agent.
The formed material may act as a filter to the nu-
trient matter, but is quite passive. The pabulum,
which is coursing through the bloodvessels, becomes
converted into germinal matter, which in turn be-
comes formed material, and so long as this is kept
up, the cell continues to grow. The course taken by
the pabulum, and the order of conversion, is shown
by the arrows, in Figure 17, of Plate, and will be
readily understood by reference to the explanation.
Occasionally, and especially, in disease, the formed
material may become the pabulum for rapidly mul-
tiplying cells, and thus be consumed.

Intercellular substance has already been spoken of
as formed material. We have it most strikingly pres-
ent in the white fibrous tissue, or tissue of tendons,
and in hyaline cartilage. If the former be stained
by carmine, and examined in thin section under the
microscope, it will be found composed of beautiful

84 THE CELL DOCTRINE.

bands of gently waving fibrous tissue, or tissue ex-
hibiting a fibrous appearance, at varying intervals in
whicb are noted nuclear masses of germinal matter,
which have assumed the tint of carmine. Or, if di-
lute acetic acid be added to the specimen, the fibrous
appearance will at once become homogeneous, while
the nuclei will be rendered distinct, and clearly visi-
ble. In young tendon (Plate, Figure 11), the masses
of germinal matter will be found very abundant, and
the intercellular fibrous substance in smaller quan-
tity than in old tendon where the masses of germinal
matter occur only at long intervals. These masses of
germinal matter, or connective tissue corpuscles, it
will be recollected, are considered by Yirchow as
perfect cells, presenting cell wall, cell contents, and
nucleus, and the fibrous intercellular substance as a
subsequent modification of a homogeneous matrix,
dropped between the cell by the bloodvessels. These
connective tissue corpuscles are regarded by Beale
as simple masses of germinal matter, the conversion
of which into formed material produces the fibrous
intercellular substance, as seen in Figure 11, Plate,
and between which and the intercellular substance
immediately adjoining, there is no line of separation,
constituting a cell wall.

As the tendon grows older, the masses of germinal
matter become less abundant, because a larger num-
ber have been totally converted into formed material;
and the bands of indestructible material which some-
times join them, and which are considered by Virchow
as a part of his canalicular system, are, according to
Beale, nothing hut imperfectly converted formed material,

THE CELL DOCTRINE. 85

or rather germinal matter, which has not been con-
verted. While the twisted and curling cord-like
fibres of the so-called yellow elastic tissue, also con-
sidered by Virchow as a part of his canalicular sys-
tem, are thought by Beale to be composed in part of
true yellow elastic tissue, such as is found in the
ligamentum nuchge, and likewise formed from nu-
clei (Plate, Figure 14), but in part also of the remains
of nerves, and vessels, which were active at an earlier
period of life.*

So, also, with hyaline cartilage. According to Beale,
the intercellular substance results from the conver-
sion of the so-called cartilage corpuscles or cells into
formed material, and here also the germinal matter
is directly continuous with the matrix, no proper cell
wall intervening.

Cartilage is not to be considered as a distinct class
of tissue from epithelium, nor can the latter, in all
cases be distinguished from cartilage by the exist-
ence of separate cells, since in many forms of epi-
thelium, at an early period of existence, the formed
material corresponding to the masses of germinal
matter is continuous throughout, and presents no
indication of division into cells.f A " cell," or ele-
mentary part, then, of fully formed tendon or carti-
lage, would consist of a portion of germinal matter,
with a proportion of formed material about it, ex-
tending to a line midway between that mass of ger-

* Beale, On the Structure and Growth of the Tissues, and on
Life. London : 1865, pp. 95, 96, and 101.

f Beale, Protoplasm; or, Life, Force and Matter. London:
1870, p. 61.

86 THE CELL DOCTRINE.

minal matter and the masses immediately adjacent,
of which the .cartilage or tendon is composed ; and
such a line would correspond to the outer part of
the surface of an epithelial cell.* In very j^oung car-
tilages, as in very young epithelium, the cells consist
of germinal matter only, with a small quantity of
soft formed material intervening; and to understand
the true relation of the cells to the intercellular sub-
stance, the tissue should be studied at different pe-
riods of its growth.

So, too, a " cell " or elementary part of muscle or
nerve, would consist of a mass of germinal matter
(the so-called nucleus), with a portion of muscular
or nervous tissue corresponding with it, and with
which it is uninterruptedly continuous.

In the formation of the contractile tissue of muscle^
the germinal matter seems to move onward, under-
going conversion at its posterior part, into the mus-
cular tissue, while it maintains itself by absorbing
and converting pabulum. This will be understood
by reference to Fig. 13. The fibres of yellow elastic
tissue are formed in precisely the same manner. (See
Plate, Fig. 14.) Nerve fibres, which in their com-
pleted state consist almost wholly of formed material,
are similarly produced. In the young state, the fibre
is composed of masses of germinal matter, linearly
arranged, and in close proximit3^ As the conversion
takes place and the fibre is produced, these become
more widely separated, and the tissue resulting from
such conversion is nerve. (Plate, Fig. 15.)

* Beale, Protoplasm, pp. 51-2.

THE CELL DOCTRINE. 87

The '^Cell^' or ^'Elementary Fari'^ in Disease,

Here, as in normal nutrition, the germinal matter
is alone active. It is impossible to state precisely
every instance, but it is probable that in the majority
of cases of disease, the morbid state consists es-
sentially in a modification of the healthy nutrition
of the cell, that is, the cell is made to grow more or
less rapidly, or is perverted in its mode of growth,
though it is likely that within certain limits, the con-
ditions under which cells ordinarily live may be
modified without deviation from health. But in in-
flammatory processes attended by local products, as
jpus or lymph, and in the production of tubercle and
cancer we see the results of excessive multiplication
and perversion of germinal matter consequent upon
the appropriation of an excess of nutrient 'pabulum.
In other instances, as cirrhosis, where there is shrink-
ing, and hardening, and wasting, we see the efl*ects
of a diminished supply of pabulum, either through
a diminution in the quantity supplied, or an imper-
meability in the septum through which it is com-
pelled to pass.

An increased supply of pabulum may be admit-
ted to germinal matter, either in consequence of
the removal of barriers through which it is ordi-
narily compelled to pass, or in consequence of the
nature of the fluids hy which it is bathed. A sim-
ple illustration is seen in suppuration in epithelium,
or the germinal matter of any tissue; for, according
to Beale, suppuration and morbid processes gene-
rally, are not restricted to any one kind of ger-

88 THE CELL DOCTRINE.

minal matter, as the connective tissue corpuscle, but
may occur in all germinal matter to which the con-
ditions are supplied. Using epithelium by way of
illustration, as the result of the increased supply of
pabulum, the germinal matter first grows, as seen in
Plate, Figs. 7 and 8, then in the luxuriance of its
growth, even at the expense of the formed matter,
sends out buds or processes, which soon drop ofi'and
become separate pus corpuscles. (Figs. 9 and 10.)
These are produced so rapidly that there is not time
for formed material to form upon their surface in any
quantity, and they have not. time, therefore, to pass
on into epithelium. Hence pus corpuscles are al-
most pure germinal matter. So soon as the process
ceases, in consequence of the supply of pabulum
being diminished, the germinal matter multiplies
less rapidly; opportunity^ is permitted for the pro-
duction of formed material on its periphery, and the
cell now passes through the different grades of epithe-
lium, as described on pages 80, 81, and 82. The pus
corpuscles are analogous to the deepest layers of
epithelial cells there referred to, which deep cells
are in fact the " mucous corpuscles," so-called, well
known to be morphologically identical with pus cor-
puscles; the former being simply the young epithe-
lial cell on its w^ay to become perfect epithelium,
while the latter is the same also, though never al-
lowed to pass into the perfectly formed state.

Again, in piieumojiia, and here we note where the
paths of Yirchow and Beale separate more widely,
the so-called " exudation," or product which fills
up the vesicular portion of the lung, considered by

THE CELL DOCTRINE. 89

Vircliow a local one, the result of a proliferation of
the connective tissue corpuscle of the part, and
having no dependence upon the blood, is regarded
by Beale as the result of a proliferation of minute
'particles of (jerminal matter (very much smaller than
white blood corpuscles), which have passed out
through the capillary walls with the liquor sanguinis.

• In all inflammatory processes and fevers, this is
believed by Dr. Beale to take place to a greater or
less extent, the little masses of germinal matter or
nuclei in the capillary walls also taking part, often
increasing in size to such degree that they materially
obstruct the passage of the blood, and by dropping
oft* portions give rise to bodies floating in the blood
precisely similar to white blood corpuscles, or pus
corpuscles; indeed. Dr. Beale considers that this may
be one of the sources of origin of the white blood cor-
puscle.*

So, also, tubercle is believed by Dr. Beale to result
either from the multiplication of masses of germinal
matter which have passed through the capillary walls
from the blood, or from the masses of germinal matter
usually termed nuclei, in connection with the capillary
walls. He says, in illustration, "In a case of tubercle,
which was very rapidly developed upon the surface
of the pia mater, in a man of tubercular constitu-
tion, I proved most distinctly, that the tubercles were
connected with the vascular walls, and that if the
nuclei had not given origin to them, they were cer-

* Beale, Microscope in Clinical Medicine, 3d ed. London :
1867, p. 166.

8*

90 THE CELL DOCTRINE.

tainly implicated. My own opinion is, that these
nuclei gave origin to the tubercle corpuscles, in con-
sequence of receiving from the blood peculiar nu-
trient matter. In the lung I have seen appearances
which point to a similar conclusion."* Would not
these views arise from appearances precisely analo-
gous to those represented as giving support to the
view, that tubercle originates in the perivascular
sheaths of bloodvessels ? The views of Beale, II.
Charlton Bastian,t and Cornil,J would then consti-
tute simply diflerent modes of expression of the same
truths.

ROBIN, E. A., POUCHET,§ 1867.

Robin, who may be considered the mouthpiece of
the French school of histologists, reduces the human
body to elementary parts, usually microscopic, which
he calls anatomical elements. The forms he makes
threefold,— ^6re5, tubes, and cells.

The fibres are generally of considerable length,
sometimes extending from the lower part of the

* Microscope in Clinical Medicine, 3d ed., 1867, p. 205.

f Bastian, H. C, Tuberc. Meningitis. Edinb. Med. Jour., 1867,
p. 875.

% Cornil, Tubercle in Connection with the Vessels. Archiv. do
Phys. Norm, et Path., Jan. et Pev., 1868.

§ Our information with regard to M. Eobin's views, is de-
rived from an admirable exposition of them published in vol. iv,
1867, of the New York Medical Journal, by Dr. Wm. T. Lusk,
who there states that he has them mainly from a course of familiar
and private instruction, furnished to him by M. C. H. Georges
Pouchet, son of the eminent physiologist, Prof. F. A. Pouchet,
Assistant to M. Kobin, Lecturer upon Anatomy and Histology to
the Ecole Pratique, author of "Un Precis d'Histologie," &c. ; so
that they may be said to be the views also of the elder Pouchet.

THE CELL DOCTRINE. 91

spinal cord to the extremity of the foot. Their di-
ameter is, however, small, often not exceeding .001
millimetre, or .00003987 of an inch.

The tubes offer as objects of study the walls and
the cavity.

The cells of vegetables have a wall, a cavity, and
contents (air, oil, &c.). The cells of animals, on the
contrary, are, as a rule, homogeneous. Animal cells
containing a cavity are only found exceptionally. The
substance of cells is ordinarily granular. Most cells
contain an ovoid nucleus more granular than the
substance itself.

In all cells the nuclei afford different chemical re-
actions from those of the substance of the element.
Each cell is an independent organism, passing through
various stages of development, from birth to death.

The birth (origin) of the elements takes place by
1st, segmentation; 2d, genesis; 3d, epigenesis; 4th,
germination.

1st. Segmentation. — The human ovum is a small
hollow sphere, containing in its interior the vitellus
or yolk, which consists of granular matter in a hya-
line substance. At the end of a certain time parti-
cles of the granular matter approximate, unite and form
a nucleus in the vitellus. Next, the nucleus elongates,
takes an hour-glass form (biscuit), then divides. The
division of the yolk occurs simultaneously. In the
same way, the division takes place into 4, 8, 16, and
more parts. These divisions of the vitellus have re-
ceived the name vitelline globules. Their mode of
formation is called segmentation.

2d. Genesis. — When the vitelline globes have be-

92 THE CELL DOCTRINE.

come very small by successive segmentation (diame-
ter .008 millimetre, .00031396 of an inch), these little
bodies take the name of eriihryonic cells.

According to M. Robin, these cells dissolve.
From the fusion results a blastema, in the midst of
which nuclei make their appearance. This is known
as genesis. It is the second and most frequent mode
of the formation of anatomical elements. It is char-
acterized by the appearance of an anatomical ele-
ment in a fluid termed blastema, in which the
element did not previously exist.

3d. Epigenesis. — When the embryonic cells dis-
solve, the embryo-plastic nuclei are produced by
genesis in the blastema which results from their
fusion. Then little cone-like prolongations of trans-
parent matter are observed at the extremities of the
nuclei, giving rise to the fusiform bodies, which are
the connective tissue corpuscles. This mode of for-
mation by growth upon another element is known
as epigenesis, and is the mode in which connective
tissue is developed. The prolongations of these fu-
siform bodies constitute the non-elastic fibres or
white fibrous tissue element of connective tissue.
Sometimes the substance deposited by epigenesis
upon the nucleus has several prolongations, forming
a stellate cell or connective tissue corpuscle. These
fusiform and stellate cells are likewise known as
embryo-plastic or fibro-plastic bodies, and this latter
term is a most common one in French histology.

The elastic fibres of connective tissue are likewise
formed by epigenesis, but upon special nuclei, and
the prolongations are insoluble in acetic acid.

THE CELL DOCTRINE. 93

There is an early period of foetal life, previous to
the formation of connective tissue, in which we find
only embryo-plastic nuclei and fusiform bodies in
amorphous matter. This is called embryo-plastic
tissue. Growth at this epoch is most rapid, the
foetus reaching in a short space of time the dimen-
sion of .030 millimetre (.0118 of an inch).

4th. Germination. — This is very frequent in vege-
tables, but in animals only one example is known,
viz., at a period previous to the fecundation of the
ovum. Before segmentation takes place the vitellus
is observed to retract. The hyaline substance pushes
out a prolongation, which becomes round, separates,
and constitutes an independent anatomical element
exterior to the vitellus, and bearing no part in the
future development of the ovum.

The following account of certain special elements
illustrates and further explains the views of M.
Eobin. Bed blood globules (hematics), diameter, .007
millimetre (^-i-Q-Q of an inch); thickness .002 millime-
tre ( 12*55 of an inch). Blood globules are elastic, — a
property enabling them to elongate, and pass through
capillaries which have a calibre less than the diam-
eter of the blood globule. They are homogeneous
throughout — i. e,, have no cell wall. Blood globules are
formed by genesis in the blood plasma. In the foetus
they make their appearance before the white blood
globules (leucocytes). In man there are two kinds
of red blood globules, viz. : fi.rst, embryonic; second,
normal. The embryonic blood globules are double
the size of the normal ones. They have a slightly
granular nucleus, situated nearly in the centre, which

94 THE CELL DOCTRINE.

is insoluble in acetic acid. The normal blood glob-
ules are not a transformation of the embryonic.
They appear by genesis in the midst of the blastema
of the blood. After the fourth month, the embry-
onic globules cease to form, and as the mass of the
blood increases, the proportionate number diminishes
with great rapidity.

Leucocytes, or white blood globules, are found in
many tissues, in the blood, on the surface of mucous
membranes; in a word, they are the pus corpuscles. In
form, they are round, with pale, well-defined borders,
and contain extremely fine gray granules. They
possess a very thin envelope, and a granular cell
contents. The normal diameter is .008 millimetre
Guuu ^^ ^^ inch). On the addition of water, the
leucocytes swell, the granular particles are agitated
by a peculiar movement (first observed by Brown),
and finally, a considerable number of these particles
unite, so as to form two or three little masses, that have
been mistaken for nuclei. Upon the addition of acetic
acid the same reaction follows, but with greater
rapidity.

The mode of production may be followed, step by
step, upon the surface of wounds, especially little
ones. At first a hyaline liquid appears. At the end
of a couple of hours, this liquid becomes finely
granular, and then all at once, in the midst of the
granulations, we perceive small granular bodies an-
alogous to leucocytes, ofiering the same chemical re-
actions, but measuring only .003 millimetre (.000118
of an inch) in diameter. They are, in fact, leuco-
cytes of young growth. When leucocytes are re-

THE CELL DOCTRINE. 95

tained in the economy, as in shut sacs, they increase
in size, and reach a diameter of .012 millimetre
(s^uTj ^f ^^^ inch). Then they fill with fat gran-
ules, and are known as corpuscles of inflammation
(exudation corpuscles, compound granule cells).
Finally the substance and investing membrane of the
leucocytes disappear, the granules dissolve and are
reabsorbed.

Capillaries. — The finest capillaries are anatom-
ical elements of tubular form, with transparent re-
sistant walls which measure .001 mm. (.00003937 of
an inch) in diameter. These walls contain granular
ovoid nuclei, which project, sometimes exteriorly,
sometimes upon the inner surface of the tubes.
These nuclei measure .006 mm. (.00023622 of an
inch) in the transverse, and .008 mm. (.00031596 of
an inch) in the long diameter. Their long axis is
parallel to that of the vessel. The finest capillaries
have a diameter of .007 mm. (.0003756 of an inch),
leaving a calibre (after deducting the walls), of .005
mm. (.00019685 of an inch), or .002 mm. (.00007874
of an inch) less than the average diameter of the
blood globules which traverse them.

They are formed as follows : 1st, In new tissues,
hollow projections push out from contiguous cap-
illaries, which meet and unite together. 2d, A
solid filament forms, in which nuclei make their ap-
pearance. Subsequently, the filament becomes hol-
low, and its nuclei remain the nuclei of the capillary.

A single perusal of these views as thus illustrated,
will convince the reader that spontaneous formation is
the prevailing .mode of origin of the elements of

96 THE CELL DOCTRINE.

tissues, according to the French school. Such pe-
rusal cannot fail to convince the reader also of the
accuracy of description of the fully formed elements
described by Robin.

PROF. HUXLEY,* 1869.

There is one kind of matter which is common to
all living beings, and that matter is "^^ro/opZa^m,"
the scientific name for "the physical basis of life."
In illustration from vegetable life, each stinging
needle or hair of the common nettle consists of a
very delicate outer case of wood, closely applied to
the inner surface of which is a layer of semi-fluid mat-
ter, full of innumerable granules of extreme minute-
ness. This semijhdd lining is protoplasm, which thus
constitutes a kind of bag, full of a limpid fluid, and
roughly corresponding in form with the interior of
the hair which it fills. When viewed w^ith a sufli-
ciently high magnifying power, the protoplasmic
layer of the nettle hair is seen to be in a condition
of unceasing activity. Local contractions of the
whole thickness of its substance pass slowly and
gradually from point to point, and give rise to the
appearance of progressive weaves, just as the bending
of successive stalks of grain \by a breeze produces
the apparent billows of a grain-field.

But in addition to these movements, and inde-
pendently of them, the granules are driven, in rela-
tively rapid streams, through channels in the proto-

* Protoplasm ; or, The Physical Basis of Life. A Lecture by
Prof. Huxley, delivered in Edinburgh, Nov. 18th, 1868.

THE CELL DOCTHINE. 97

plasm which seem to have a considerable amount of
persistence. The currents in adjacent parts com-
monly take similar directions, coursing in a general
stream up one side of the hair and down the other,
though partial currents also exist which take differ-
ent routes; so that sometimes trains of granules
.may be seen coursing swiftly in opposite directions,
within a twenty-thousandth of an inch of each other;
and occasionally opposite streams come in direct
collision, and after a longer or shorter struggle, one
predominates. The cause of these currents seems
to lie in contractions of the protoplasm which bounds
the channels in which they flow, but which are so
minute that the best microscopes show only their
effects, and not themselves.

Among the lower plants, it is the rule rather than
the exception, that contractility should be still more
openly manifested at some periods of their existence.
The protoplasm of Algse and Fungi becomes, under
many circumstances, partially or completely freed
from its woody case, and exhibits movements of its
whole mass, or is propelled by the contractility of
one or more vibratile cilia.

In illustration of animal protoplasm. Prof Hux-
ley adduces the colorless corpuscles of the blood;
which, under the microscope, at the temperature of
the body, exhibit a marvellous activity, changing
their forms with great rapidity, drawing in and
thrusting out prolongations of their substance; and
creeping about as if they wxre independent organ-
isms. " The substance which is thus active is a
mass of protoplasm, and its activity differs in detail

9

98 THE CELL DOCTRINE.

rather than in principle from that of the protoplasm
of the nettle. Under sundry circumstances the cor-
puscle dies, and becomes distended into a round
mass, in the midst of which is seen a smaller spheri-
cal body, which existed, but was more or less hid-
den, in the living corpuscle, and is called its nucleus.
Corpuscles of essentially similar structure are to
be found in the skin, in the lining of the mouth,
and scattered through the whole framework of the
body. I^ay, more; in the earliest condition of the
human organism, in that state in which it has just
become distinguishable from the egg in which it
arises, it is nothing but an aggregation of such cor-
puscles, and every organ of the body was, once, no
more than such an aggregation. Thus a nucleated
mass of protoplasm turns out to be what may be termed
the structural unit of the human body. As a matter of
fact, the body, in its earliest state, is a mere mul-
tiple of such units; and, in its perfect condition, it
is a multiple of such units, variously modified."
The formula which expresses the essential structural
character of the highest animal, very nearly covers
all the rest, as the statement of its powers and
faculties covered that of all others. "Beast and
fowl, reptile and fish, mollusk, worm, and polype,
are all composed of structural units of the same
character, namely, masses of protoplasm with a nu-
cleus. There are sundry very low animals, each of
which, structurally, is a mere colorless blood cor-
puscle, leading an independent life. But, at the very
bottom of the animal scale, even this simplicity be-

THE CELL DOCTRINE. 99

comes simplified, and all the phenomena of life are
manifested by a particle of protoplasm without a nucleus,

" What has been said of the animal world is no less
true of plants. Imbedded in the protoplasm at the
broad, or attached end of the nettle hair, there lies
a spheroidal nucleus. Careful examination further
proves that the whole substance of the nettle is made
up of a repetition of such masses of nucleated proto-
plasm, each contained in a wooden case, which is
modified in form, sometimes into a woody fibre,
sometimes into a duct or spiral vessel, sometimes
into a pollen grain, or an ovule. Traced back to its
earliest state, the nettle arises as the man does, in a
particle of nucleated protoplasm. And in the low^est
plants, as in the lowest animals, a single mass of such
protoplasm may constitute the whole plant, or the
protoplasm may exist without a nucleus. Under
these circumstances it may well be asked, how is one
mass of non-nucleated protoplasm to be distinguished
from another? why call one * plant,' and the other
* animal?' The only reply is that, so far as form is
concerned, plants and animals are not separable, and
that, in many cases, it is a mere matter of conven-
tion whether we call a given organism an animal or
a plant."

The researches of the chemist have also shown a
like uniformity of chemical composition in " proto-
plasm " or living matter, proving that whatever its
source, it contains carbon, hydrogen, oxygen, and
nitrogen, producing in their combination a complex
substance, whiib iH»q\i)^ i'gi:^i>ai;ce^of jtf mor^;6xact
nature, we Q2i\\'pfoieinaceousdv Ulbuvlirioid muittr.

100 THE CELL DOCTRINE.

Thus far it is plain that the views of Prof. Huxley
accord with those of many eminent histologists and
physiologists, the result of whose observations have
been embodied in these pages, and his descriptions
will be accepted as undoubtedl}^ accurate. More
widely, in common with the school of so-called
" physicists," of which he is one, does he differ in
his views in that which is yet to be considered, the
origin and ultimate fate of this "protoplasm," or
matter of life. According to Prof. Huxley, the
matter of life is composed of ordinary matter, and
again resolved into ordinary matter when its work
is done. Waste is constantly going on which must
be supplied by food, which is converted into proto-
plasm. A solution of smelling salts in water, with
an infinitesimal proportion of some other saline mat-
ters, contains all the elementary bodies which enter
into protoplasm, yet an animal cannot make proto-
plasm. And this is characteristic. It must take it
ready made from some other animal or some plant,
the animal's highest feat of constructive chemistry
being to convert dead protoplasm into the living
matter of life, which is appropriate to itself There-
fore, in seeking for the origin of protoplasm, we
must eventually turn to the vegetable world. The
plant, however, takes carbonic acid, water, and am-
monia, and converts it to the same stage of living
protoplasm with itself, though some of the fungi
need higher compounds to start with; and no plant
can live on the uncompounded elenients of proto-
plasni^^djthe abseilce of aay.^Re'^t the elements
renders the ptant unable to Tnariufacture protoplasm.

THE CELL DOCTRINE. 101

These elements, carbon, hydrogen, ox3^gen, and ni-
trogen, are related to the protoplasm of the plant
as the protoplasm of the plant to the animal. But
protoplasm once i^roduced, all the phenomena exhibited
by it are simply its properties, just as the phenomena
exhibited by water in its various states are properties.
They do not take place through the guidance of any
principle called " vitality," any more than the phe-
nomena of water take place by virtue of " aquosity."
Prof. Huxley can discover no halting-place between
the admission that protoplasm of one animal or vege-
table is essentially identical with and readily con-
verted into another, and the further concession that
all vital action may, with equal propriety, be said to
be the result of the molecidar forces of the protoplasm
which displays it. The thoughts to which we give utter-
ance are the expression of molecular changes in proto-
plasm. These are admittedly so-called materialistic
terms. Yet Prof. Huxley says : " I^fevertheless, two
things are certain: the one that I hold the state-
ment (above) to be substantially correct; the other,
that I, individually, am no materialist, but on
the contrary believe materialism to involve grave
philosophical errors." Such union of materialistic
terminology with the repudiation of materialistic
philosophy, he believes to be " not only consistent
with, but necessitated by sound logic." This he
proceeds to show in this manner : If it be supposed
that knowledge is absolute, that we know more ot
cause and eftect than a certain definite order of suc-
cession of facts, and that we have a knowledge of
the necessity of that succession, then there is no

9*

102 THE CELL DOCTRINE.

escape from utter materialism and necessarianism.
But it is impossible to prove that anything what-
ever may not be the eflect of a material and neces-
sary cause, and no act is really spontaneous, since a
really spontaneous act is one which has no cause.
Yet any one familiar with the history of science will
admit that its object has always meant, and means
the extension of the province of matter and causa-
tion, and the concomitant gradual banishment from
all regions of human thought, of what we call spirit
and spontaneity, — that is, the object of all science
has been and is to find out the causes of all phe-
nomena; and there is no difference between the
conception of life as the product of a certain dispo-
sition of material molecules and the old notion of an
Archseus governing and directing blind matter within
each living body, except that here, as elsewhere, mat-
ter and law have devoured spirit and spontaneity.
And moreover, the physiology of the future will
gradually so extend the realm of matter and law,
until it is coextensive with knowledge, with feeling,
and with action. It is this j^rogress of knowledge^
according to Prof. Huxley, which so many of the
best minds conceive to be the progress of material-
ism^ which they watch with such fear and powerless
anger as a savage feels, when, during an eclipse, the
great shadow creeps over the face of the sun. We
know nothing of this terrible *^ matter," except as
the name for the unknown and hypothetical cause of
states of our own consciousness, and as little of that
" spirit," except that it is also a name for an un-
known and hypothetical cause of states of conscious-

THE CELL DOCTRINE. 103

ness, that is, matter and spirit are both names for
the imaginary substrata of groups of natural phe-
nomena. Dire necessity and " iron " law are gratu-
itously invented bugbears. If there be an " iron "
law, it is that of gravitation, and if there be a phys-
ical necessity it is that a stone unsupported will fall
to the ground. We know nothing more of this latter
phenomenon, except that stones always have fallen
to the ground under these conditions, and that they
will continue to fall to the ground thus unsupported.

It is simply convenient to indicate that all the con-
ditions of belief in this case have been fulfilled, by
calling the statement that unsupported stones will
fall to the earth a " law of nature." But when for
will we exchange must, we introduce an idea of neces-
sity which does not lie in the observed facts, and is
not warranted by anything that is discovered else-
where. And with regard to which Prof Huxley
says: "For my part, I utterly repudiate and anathe-
matize the intruder. Fact I know, and Law I
know; but what is this IlTecessity, save an empty
shadow of my own mind's throwing? But, if it is
certain that we can have no knowledge of the nature
of either matter or spirit, and that the notion of
necessity is something illegitimately thrust into the
perfectly legitimate conception of law, the materialis-
tic 'position that there is nothing in the world hut matter,
force, and necessity, is as utterly devoid of justification as
the most baseless of theological dogmas.

" The fundamental doctrines of materialism, like
those of spiritualism, and most other *isms,' lie out-
side *the limits of philosophical inquiry,' and David

104 THE CELL DOCTRINE.

Hume's great service to humanity is his irrefragable
demonstration of what these limits are. Hume
called himself a skeptic, and therefore others cannot
be blamed if they apply the same title to him; but
that does not alter the fact that the name, with its
existing implications, does him gross injustice. If
a man asks me what the politics of the inhabitants
of the moon are, and I reply that I do not know;
that neither I, nor any one else have any means of
knowing; and that, under these circumstances I de-
cline to trouble myself about the subject at all, I do
not think he has any right to call me a skeptic. On
the contrary, in replying thus, I conceive that I am
simply honest and truthful, and show a proper regard
for the economy of time. So Hume's strong and
subtle intellect takes up a great many problems
about which we are naturally curious, and shows us
that they are essentially questions of lunar politics,
in their essence incapable of being answered, and
therefore not worth the attention of men who have
work to do in the world." ....

"If we find that the ascertainment of the order of
nature is facilitated by using one terminology, or one
set of symbols, rather than another, it is our clear
duty to use the former, and no harm can accrue so
long as we bear in mind that we are dealing merely
with terms and symbols. In itself it is of little
moment whether we express the phenomena of mat-
ter in terms of spirit, or the phenomena of spirit in
terms of matter ; matter may be regarded as a form
of thought, thought may be regarded as a property
of matter — each statement has a certain relative

THE CELL DOCTRINE. 105

truth. But with a view to the progress of science,
the materialistic terminology is in every way to be
preferred. For it connects thought with the other
phenomena of the universe, and suggests inquiry
into the nature of those physical conditions, or con-
comitants of thought, which are more or less acces-
sible to us, and a knowledge of which may, in future,
help us to exercise the same kind of control over
the world of thought as we already possess in respect
to the material world; whereas, the alternative, or
spiritualistic terminology is utterly barren, and leads
to nothing but obscurity and confusion of ideas.
Thus, there can be little doubt that the further science
advances, the more extensively and consistently will
all the phenomena of nature be represented by ma-
terialistic formulae and symbols. But the man of
science, w^ho, forgetting the limits of philosophical
inquiry, slides from these formulae and symbols into
what is commonly understood by materialism, seems
to me to place himself on a level with the mathema-
tician, who should mistake the x's and y^s, with
which he works his problems, for real entities — and
with this further disadvantage, as compared with the
mathematician, that the blunders of the latter are of
no practical consequence, while the errors of sys-
tematic materialism may paralyze the energies and
destroy the beauty of a life."

These are the views of the "physicists," so-called,
a school represented by Prof. Huxley, Prof. Owen,
Herbert Spencer, Mr. Grove, Prof. Tyndall, and
others. Prof. Owen, in the last pages of vol. iii of
" The Anatomy of the Vertebrates," declares him-

106 THE CELL DOCTRINE.

self the champion of spontaneous generation, and he
maintains, also, that the formation of living beings
out of inanimate matter by the conversion of physi-
cal and chemical into vital modes of force, is a mat-
ter of daily and hourly occurrence. Mr. Grove says
that " in a voltaic battery and its effects we have
the nearest approach man has made to an experi-
mental organism," and that in the human body we
have chemical action, electricity, magnetism, heat,
light, motion, and possibly other forces "contribut-
ing, in the most complex manner, to sustain that
result of combined action we call life.'*

We trust it is not necessary to state that it has
been attempted to state these views, not in a spirit of
criticism, but fairly and justly; our object in this
connection being simply to exhibit the present state
of the subject as viewed from all standpoints. And
in the case of this class of eminent observers we have
based our account almost entirely on what we believe
the latest exposition of the subject, viz.. Prof. Hux-
ley's lecture, while we have included, also, such
quotations of pregnant sentences of other observers
of the same class, as seemed essential to complete-
ness and consistent with brevity.

THE author's VIEWS.

As the result of a careful comparison of the views
of other observers, and of personal observation, ex-
tending over a period of several years, chiefly in
the direction of human physiology and pathology,
the author has been led to adopt views, which, in
the main, correspond with those of Dr. Beale. There

THE CELL DOCTRINE. 107

are, however, a few points of difference; some, per-
haps, purely in mode of expression, but others as to
matter of fact, which would seem to be appropriately
here recorded. And, in order to give completeness
to any expression of such views, he has thought best
to state them connectedly, though briefly.

The author believes the ultimate physical element
of organization, to be what is commonly called the
" cell," or " elementary part," and that it is com-
posed of matter in two states. The one, central in
its situation, to which Dr. Beale has most appropri-
ately given the name "germinal matter;" the other,
for the most part peripheral in its situation, which
the same observer has called " formed matter." The
former, which is the " sarcode " of Dujardin, the
"protoplasm" of Max Schultze, is that upon which
the origin and existence of the cell depends. It is de-
rived by division, budding or proliferation from pre-
viously existing matter of the same kind, and it alone
has the power of growing by converting nutritious
matter or "pabulum," derived from the blood or
other sources, into material like itself. Without
germinal matter textures cannot be reproduced or
continued.

In appearance, germinal matter is often structure-
less, especially as constituting the living moving
matter of the protozoa or lowest animals of the
rhizopod type, as the amoeba. Yet it is not always
structureless, but often granular in its appearance,
and as constituting the mass of rapidly growing
cells in health and disease, in the higher animals,
is indeed usually granular, as is evident from the

108 THE CELL DOCTRINE.

study of pus, or mucous, or white blood corpuscles,
or the cells of a rapidly growing morbid growth. In-
deed it seems like sacrificing observation to theory,
to say that germinal matter is always structure-
less. For let us take the white blood corpuscle or
pus corpuscle, acknowledged to be pure germinal
matter, and always described as granular in its struc-
ture; either the germinal matter here is granular,
or the granules are particles of formed material or
extraneous matter suspended in the formless sub-
stance, just as granular matter from without be-
comes entangled in the formless matter of the am-
oeba. But, such a view as the latter, would be
incompatible both with the behavior of growing
germinal matter, and the reaction by which it is
known; for we note, on the one hand, that when
germinal matter grows rapidly, these granules are
the elements which increase most abundantly; and
again, that these are the portions most deeply stained
by ammoniacal solutions of carmine or aqueous so-
lutions of red aniline. Especially must this be the
case if the so-called nuclei of these bodies, which
appear after the addition of water and acetic acid,
are simple aggregations of the granular matter, as is
contended by Dr. Beale. We deem it incorrect,
therefore, to describe germinal matter as in all in-
stances structureless, and prefer, with Robin, to de-
scribe it as sometimes granular. Indeed, if we mis-
take not. Dr. Beale in his earlier descriptions also
characterized it as granular.*

* Beale's Archives of Medicine, vol. ii, p. 189.

THE CELL DOCTRINE. 109

A circumscribed round or oval portion of germinal
matter within the cell is usually termed the nucleus,
which may be surrounded by formed material as in
the superficial epithelial cell, or by other germinal
matter as in the white blood corpuscle.

In the nutrition of the cell, the pabulum comes
to it from the periphery; being strained through the
formed material, and the new germinal matter takes
its place in or near the centre of the original mass,
constituting a new centre of germinal matter, which
may be the nucleus, if no other circumscribed centre
be present, or the nucleolus if it be deposited within
such a centre. Other new centres may again take
position within these, and assume the relation ot
nucleolus to the original nucleolus, which now be-
comes the nucleus, an older centre of germinal mat-
ter; while the original nucleus has probably been
converted into the second constituent of the cell, the
formed material.

Germinal matter when free and living, exhibits a
power of movement, both in portions of its substance,
producing changes in shape, and in its entire mass,
resulting in changes of position. The former, and
probably, also, the latter, may have for their object
the obtaining of pabulum, as is seen in the amoeba,
when it embraces by its protrusions, a particle of nu-
tritive matter. These movements are less decided in
the cells of the higher animals, yet they are of con-
stant occurrence, as in pus and white corpuscles, and
when thus occurring they are spoken of as " amoeboid
movements." Allied or identical with this second
class of movements, are those of undoubted occur-

10

110 THE CELL DOCTRINE.

rence, in which white blood corpuscles have been
noted by Addison,* Waller,t and Cohnheim,J mi-
grating from the bloodvessels, and constituting one
method of origin of pus.

Formed Material, or Non- Germinal Matter,— As the
result of influences, the exact nature of which is not
known, though some of them may partake of the
character of oxidations, the germinal matter is con-
verted into the second constituent of the cell, formed
material This formed material, peripheral, for the
most part in its situation, and constituting the cell
wall, when present, is without the property of ger-
minating, or multiplying itself, or even maintaining
itself. Yet it is exceedingly important, and as essen-
tial indeed to the functions of the economy, as the
germinal matter. It is, in fact, the portion of the
cell in which alone function resides, since it is to the
formed material of the muscle-cell that we owe the
property of contractility, to the formed material of
the nervous element that we are indebted for neu-
rility, and to the formed matter of the epithelial cell
that we owe its protective qualities; while the se-
cretion of all glands, whether they subserve ulterior
purposes or not, is the formed material of the re-
spective gland-cells. Hence, we would not in every
instance speak of the formed material as dead, where
it is the seat of so many important vital endowments,

* Addison, Physiological Eesearches. London : 1841.

f "Waller, London, Dublin and Edinburgh Philosophical Maga-
zine, vol. xxix, p. 271, 1846.

X Cohnheim, Ueber EntzUndung und Eiterung, Virch. Arch.
Bd. xl, p. 48.

THE CELL DOCTRINE. Ill

as in muscle and nerve. In some situations, it is
indeed lifeless, as when it becomes the secretion of
glands, as bile and milk, or the peripheral part of
epithelial cells. It simply is devoid of a power of
multiplying or growing by itself, depending for its
increase upon the conversion of the germinal matter.
Hence w^e have been inclined to suggest the term
"non-germinal,"or" non-germinating" matter, since
this is the only attribute common to all formed ma-
terial.

In structure, formed material or non-germinal mat-
ter is varied. Thus, it is typically without structure
in the red blood disc; again it exhibits distinctive
structure in the striped sarcous matter of muscle,
and in the fibrous intercellular substance of white
fibrous tissue or fibro-cartilage.

As formed material is produced on the periphery
of germinal matter, previously existing formed ma-
terial is pushed outward, so that the oldest formed
material is that most remote from the germinal mat-
ter, and the youngest lies immediately adjacent to it.

Intercellular substance, whether of cartilage or white
fibrous tissue, is formed material, resulting from the
conversion of the germinal matter, which constitutes
the cartilage corpuscle on the one hand, or the con-
nective tissue corpuscle on the other. It is not of
the nature of a deposit from the bloodvessels which
subsequently becomes difi*erentiated. Young carti-
lage cells, like all young cells, consist of almost pure
germinal matter, and the capsule of the cartilage
corpuscle is but formed material, more or less con-
tinuous and inseparable from the intercellular sub-

112 THE CELL DOCTRINE.

stance; so that we would, with Beale, define a carti-
lage cell, or elementary part of cartilage as com-
posed of germinal matter, with as much surrounding
formed material as extends half way to the adjacent
germinal matter. So with the elementary part of
connective tissue, muscle, and nerve.

Oil and starch are also formed matter, conveniently
designated by Dr. Beale as secondary formed matter,
and result, also, from a conversion of the germinal
matter.

As already stated, the proportion in which these
two constituents are present, is various. Thus, in
the amoeba, in the white blood disc, in the pus and
mucous corpuscle, we have almost pure germinal mat-
ter, with a scarcely appreciable ring of formed mat-
ter on its periphery; while in the old epithelial cell
we have almost pure formed material with a mere
point of germinal matter, constituting the nucleus
near its centre; and in the red blood disc, we have
pure structureless formed matter, yet matter of which
we should long hesitate to speak as dead. In old
tendon, again, the proportion of formed material is
large, and germinal matter small, while in young
tendon the reverse proportion exists.

The cell, as thus constituted, and originating only
in the germinal matter of a previously existing cell,
we believe to be the stariing-point of all life action, be it
healthy or morbid. Out of this cell, all tissues, simple
and complex, are constructed.

We believe, also, that the proper shaping, arrange-
ment, and function of these elementary parts is not a
process identical or analogous to crystallization, tak-

THE CELL DOCTRINE. 113

ing place through merely physical laws, but that there
is a presiding agency which controls such arrange-
ment to a definite end. It matters not what this is
called, but we prefer to designate it at present by the
term " vital force," or " vitality." It is this controlling
agency which makes all so-called vital properties es-
sentially different from purely physical properties, a
difference which, though it be denied in ivords, and ex-
plained away by reasoning, has the most decided proof
of its existence in the acknowledgment it receives in
the actions of men, just as the most convincing argu-
ment in favor of the free agency of the human mind is
seen in the fact, that all men shape their actions on
the supposition of such a freedom, whatever their
pretended belief with regard to it.

That there is something in this force or power over
and above the physical forces of nature, is most
strikingly shown in the power, exhibited through its
agency by germinal matter, of multiplying and pro-
ducing new germinal matter out of pabulum unlike
itself. For although a crystal may result from the
rearrangement of particles of a salt in solution, as
sulphate of alumina, to an unlimited extent, there is
no possibility, nor would any physicist contend that
it could produce crystals, of its own composition, out
of carbonate of soda. Nor, as is justly contended by
Dr. Beale, should the cell be compared to a machine,
unless that machine possess a power of producing
new machines out of material unlike itself, and of
endowing them with a similar power.

In morbid 'processes, also, the germinal matter is the
seat of activity, being abnormally increased, dimin-

10*

114 THE CELL DOCTRINE.

ished, or perverted; and many pathological states are
rationally explained by bearing in mind the proper-
ties of germinal matter and the very minute size which
the living particles may exhibit. All physical diffi-
culties in the way of the passage of white blood cor-
puscles through the w^alls of capillaries are removed,
when we remember that the smallest living particles
by the rapid growth of which white blood discs or pus
corpuscles are speedily produced, do not exceed the
ttjtjVtju of an inch in diameter, and that however un-
reasonable it may appear for a body ^q\q of an inch
in diameter to migrate through continuous capillary
walls, it becomes much less unreasonable when we
thus reduce its proportions. The observations of
Beale would also seem to reconcile the discordant
views with regard to the so-called exudations, in
which on the one hand we need not suppose an ex-
cessive dislocation of structure to admit the passage
of large cells, and on the other are not compelled to
restrict the origin of those cells to points outside
the vessels. We have already expressed that the
views of H. Charlton Bastian and Cornil, w^ith regard
to the origin of tubercle in the perivascular sheaths
of vessels, are not practically different from those
earlier expressed by Beale as to its origin in the
germinal matter of the walls of bloodvessels.

It will be noted that the only points of difference
between our own and the views of Dr. Beale, lie in
the structure of the germinal matter, and the use of
the word dead to characterize formed material. In
all other respects, we accept the theory of Beale,
and have no hesitation in saying that it admits, with-

THE CELL DOCTRINE. 116

out distortion of its own principle or disregard of
actual facts, of consistent application to a larger num-
ber of processes of tissue-building in health and dis-
ease, than any other theory proposed.

In conclusion, then, it may be stated, 1st, that
the " cell," or " elementary part," originating only
in a pre-existing cell, is the ultimate morphological
element of the tissue of animals and plants.

2d. That the cell, contrary to the belief of the
earlier histologists, and, indeed, many later observ-
ers, is rarely vesicular in its structure, but generally
more or less solid throughout.

3d. That the cell is composed of "germinal" or
living matter which is central, and includes " nu-
cleus," "endoplast," "protoplasm" and "sarcode;"
and of " non-germinal," or " formed" matter, which
is peripheral, and corresponds with "cell wall" and
"intercellular substance."

4th. That this germinal matter of the cell in a
part or all of its substance, may assume a special
morphological state, usually round or oval, com-
monly known as the " nucleus" of the cell, which,
when present, is always a young centre of germinal
matter; but that in other instances both animal and
vegetable cells may be complete without this special
form of germinal matter or " nucleus," as in the non-
nucleated amoebae and protogenes primordialis of
Haeckel, the non-nucleated monads of Cienkowsky,
and in the leaf of Sphagnum, in such Algae as Hy-
drodictyon, Vaucheria, and Caulerpa, and in young
germinating ferns.

5th. That in consequence of these facts, it cannot

116 THE CELL DOCTRINE.

be said that in the nucleus alone resides the power to
reproduce the cell, since we find the nucleus not
essential, but that in the germinal matter, of which
after all, the nucleus, when present, is but a part,
resides this function.

6th. That when the smaller body within the nu-
cleus, usually known as the " nucleolus," is present,
as it often is in complete cells, it is simply a younger
centre of germinal matter than is the nucleus itself,
and is the last formed portion of germinal matter,
instead of being the oldest part of the cell, as orig-
inally taught by Schleiden and Schwann. And
thus, according to the latest views, the whole process
is reversed. The old order of succession being, 1st.
The "nucleolus;" 2d. About this the "nucleus;"
and finally about this the "cell wall," which em-
braces the cell contents. Now, however, what con-
stitutes the "cell wall" when present, is the oldest
part of the cell; next in age are the so-called "cell
contents," whether germinal matter or not; next the
" nucleus," and last and youngest the " nucleolus."

7th. That the formed material constituting the
cell wall and intercellular substance may be some-
thing chemically different from the germinal matter,
or protoplasm whence it was converted, as the secre-
tions of gland-cells, or may be a simple condensation
of the exterior of the cell, as iu the red blood disc.

8th. That the so-called " free nuclei," so often re-
ferred to by pathologists in their descriptions of mi-
nute structures, are simply masses of germinal matter,
smaller than those to which the name cell is usually
given, which, if time be permitted, will pass into

THE CELL DOCTRINE. 117

perfect cells by the usual production of formed mat-
ter on their periphery; that they do not originate
spontaneously, but from previously existing germi-
nal matter. So, too, " granules," if they be com-
posed of germinal matter, present the same attributes
and endowments, arising from previously existing
germinal matter, capable of growing, multiplying,
and assuming all the characters of fully formed cells,
but never originating spontaneously. Granules
otherwise composed are histolytic (ktzo^, a tissue, Xuatq,
a breaking), and 7iot histogenetic (iffroq, a tissue, y£V£(Tt<:,
creation), — that is, they result from the breaking
down of tissue rather than go to building it up.

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