92 
NATURE 
[Fune 1, 1871 

they are bounded by no membranous wall ; and, when one of 
the threads comes in contact with an organic particle in the 
water, the particle sinks into it, and then the thread begins to 
flow back again into the body of the animal bearing the particle 
with it, asa stream of treacle might entangle, and carry along a 
crumb of bread. 
The organic particles are introduced into the body, into any 
part of it, and there they are dissolved and assimilated. I believe 
that the granules observed in the gelatinous substance are par- 
ticles of the various products of this assimilation, and that the 
living matter is perfectly homogeneous and transparent. If the 
creatures be kept for a few days in water nearly pure, they be- 
come less and less granular. 
If the thread-like pseudo-podia, as they are called, be rudely 
touched, they at once contract, and flow rapidly back into their 
test. The membranous test cannot be truly regarded as a part 
of the animal, it is a mere excreted defensive covering incapable 
of any further change, or of manifesting any of the phenomena of 
life. The body of the animal can be easily squeezed out of it 
entire, and in that case it shortly begins the excretion of a new 
shield. 
Here, then, we have a homogeneous substance which has the 
power of inducing and controlling chemical and physical forces, 
and of moulding into indefinite form the products of the regu- 
lated changes taking place within it, which therefore possesses 
life. The gelatinous matter which in this animal and in the whole 
sub-kingdom to which it belongs can thus feed and digest without 
a mouth or stomach, contract without muscles, display irritability 
without a nervous system—in fact, exhibit all the essential phe- 
nomena of living beings without a trace of -organisation, is 
Protoplasm. 
If now, laying aside the Gromia, we examine with the micro- 
scope the water-plant on which we found it, we find that the 
whole plant from end to end and in all its parts is honeyecombed, 
that is to say, composed of a congeries of minute chambers sepa- 
rated from one another by well-defined walls, the walls giving the 
plant its support and consistency. 
We place in the field of the microscope a small portion of the 
growing point of a leaf or stem, and we easily make out that the 
chambers are minute vesicles each complete in itself, adhering 
according to a definite arrangement to one another. As these 
cells have occupied a very prominent position in modern 
histological and physiological speculation, having been re- 
garded, and being still regarded by many as the units of 
organisation, the centres and sources of all vital activity, 
I should wish to sketch distinctly their structure and properties. 
It is of no consequence whence the cell is selected. All vege- 
table cells appear to have the same structure at first, during their 
growth and while their vitality lasts ; subsequently most of them 
undergo great changes, their walls being thicker and their 
cavities clogged with various secretions. There are some beautiful 
transparent-beaded hairs at the bottom of the flower cup of the 
white variety of the Virginian spider-wort. If we place one of 
these hairs in a drop of water in the field of the microscope, we 
find that it is simply composed of a row of oval cells attached 
endtoend. The cell is in this case a minute vesicle with an 
extremely thin transparent wall. This wall consists of cellulose, 
a substance composed of thirty-six parts of carbon and thirty 
parts of water. The membrane is perfectly structureless under 
the highest powers of the microscope, and apparently continuous. 
Tt must, however, be minutely perforated, for water and various 
secretions and excretions pass through it freely. From its composi- 
tion and structure it is impossible to imagine that vital force 
should reside in the vegetable cell-wall. We must regard it as 
an excretion of dead matter moulded as a boundary wall to the 
cell cavity by some external agent, but incapable of originating 
any vital action. The cell is full of water or mucous solution, 
and watching carefully with a proper arrangement of the light, and 
a moderately high power, we can distinctly trace threads of dense 
gelatinous matter moving slowly into the inner surface of the 
cell-wall. These streams commence wider in the region of a 
nucleus, which was at one time regarded as the heart of the cell, 
as it were, the centre of its vital activity, and gradually branch 
and diminish at a distance from it. Under the microscope 
granules appear in these streams, and with these granules em- 
bedded in them, as crumbs are embedded in a stream of treacle, 
the currents flow round and round the cell, the granules gradually 
disappearing and being absorbed. The observations of Prof. 
Max Schultze and of others haye, I think, placed it beyond a 
doubt that this gelatinous substance occurring within the living cell, 
and forming, at all events, a large proportion of the cell-contents, 


is identical with the protoplasm which forms the entire substance 
of such an animal form as Gromia. 
The necklace-like hair of the spider-wort is, in fact, a chain 
of cells with dead cellulose walls, and each with a living Gromia 
body imprisoned within it. 
Now, although the power which plants possess of fixing carbon 
and combining it with the elements of water, is the character 
which practically distinguishes the Vegetable from the Animal 
kingdom, I have already shown that we cannot regard this as 
by any means a universal test. In this respect broomrapes and 
dodders are animals. 
When we pass down by any path we choose, either through 
animals or plants, we come equally to a great series of very 
simple forms—mere little masses of protoplasm with a nucleus. 
Some of these contain peculiarly formed masses of bright colour- 
ing matter, green, scarlet, or yellow, and with the possession of 
such pigment we usually associate the power of decomposing 
carbonicacid. Many of these bodies have, however, no colouring 
matter at all, except what is derived from their food. A large 
number of these simple forms are enclosed in a wall of cellulose, 
but very many of them are naked or merely covered with a 
pellicle of firmer protoplasm ; while some, such asthe plasmodia 
of the myxogastric fungi are, for some part of their lives, en- 
closed in a cellulose wall, and for another part, naked. Going 
still lower, we have Haeckel’s Monera, differing from the others 
merely in the absence of a nucleus and the total want of differen- 
tiation of any part. Even these last are sometimes coloured, and 
from their chemical reactions it seems very likely that they pos- 
sess some low form of the peculiar vegetable power. Now, the 
question is, whether all these considerations lead in any way in 
the direction of establishing a separate kingdom for these simple 
beings. I think decidedly not, but it seems to me that they 
prove almost to demonstration that organic nature must be taken 
as one whole, that the Animal and Vegetable kingdoms are 
absolutely continuous, and that a tree flinging its green flags 
into the sunshine and feeding on the winds of heaven, is essen- 
tially nothing more than a vast colony of a protozoon, com- 
parable toa gigantic nummulite, only building a cellulose instead 
of a calcareous shell, and developing a special secretion in special 
organs for the purpose of enabling it to doso, 

MR. BENTHAM’S ANNIVERSARY ADDRESS 
TO THE LINNEAN SOCIETY 
HAVING now for the tenth time the honour of addressing 
you from this chair on the occasion of your annual gather- 
ing, it has been my wish to lay before you a general sketch of the 
progress making in systematic Biology, the foundation upon 
which must rest the theoretical and speculative, as well as the 
practical, branches of the science, to report upon the efforts made 
further to investigate, establish, and extend that foundation, and 
to convert the numerous quicksands with which it is beset into 
solid rock. This subject formed the chief portion of my address 
of 1862, and again of those of 1866 and 1868; but on the 
present occasion I have had some difficulties to contend with. 
Mr. Dallas, to whose kindness I owed the zoological notes I 
required, has now duties which fully absorb his time, and I have 
been obliged to apply to foreign correspondents, as well as to my 
zoological friends at home, for the necessary information. They 
have one and all responded to my call with a readiness for which 
I cannot too heartily express my thanks ; and if there is some 
diversity in the extent and nature of the information I have 
received from different countries, which may prevent any very 
correct estimate of the comparative progress made in them, it is 
owing to the questions which I put having been stated too 
generally, and, though sent in the same words to my different 
correspondents, they have been differently understood by them. 
In such a review, however, as I am able to prepare, I propose 
chiefly to consider the relative progress made by zoologists and 
botanists in the methods pursued and the results obtained, in the 
first place as to general works common to all countries, and 
secondly as to those which are more particularly worked out in 
or more specially relate to each of the principal states or nations 
where biological science is pursued, prefacing this review by a 
few general remarks supplementary to those I laid before you in 
my first address in 1862. 
Since that time systematic biology has tc a certain degree been 
cast into the background by the great impulse given to the more 
speculative branches of the science by the promulgation of the 

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