724 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
{[March 11, 1871. 
form of zoospores. If you take a piece of this sea¬ 
weed, and put just the edge where the green and 
white join under the microscope, you will see the 
spectacle that astonished me some thirty years ago, 
when I believe no one else in this country had ob¬ 
served it. An eminent Swedish naturalist had 
observed it, but I believe I was the first to see that 
very wonderful spectacle in England. It was really 
like a swarm of bees,—the multitude of these minute 
particles that had issued forth in active motion from 
the cells, and were issuing forth, for I saw them ac¬ 
tually coming out from the cells just on the border of 
the white or empty portion. That is one of the most 
familiar phenomena that may be observed on the 
seacoast, and there are many fresli-water Conferva 
which show you precisely the same. 
This motion, then, is a very common phenomenon 
amongst the lower Plants ; and when we once come 
to appreciate that, we see that it is really the key to 
the interpretation of a great many other phenomena 
which had been previously wrongly viewed. For 
instance, I have here a representation of a favourite 
object with microscopists, which was called, long 
after I began the study, the globe animalcule, or 
Volvox globcita. They are some of the most beautiful 
things that can be seen under the microscope, and 
consist of globular bodies, rolling on and on, turning 
on their axes, swimming through the water, and 
studded all over with beautiful little green points ; 
and they very commonly have in their interior other 
green globular masses. It may surprise you to be 
told that this is unquestionably a Plant. We can 
now trace those as the highest, the most specialized 
forms of a tribe of plants which shows itself in 
various grades of simplicity, from the single little 
green cells with one or two vibrating filaments, by 
the agitation of which it moves, up to a form as 
complicated as the one here represented. Here are 
diagrams of some of the less complicated forms, but 
you will easily see that they differ only in form and 
not in essential organization, because it is the single 
cell and its vibrating filament which is the essence 
of the whole thing in every case. We find that 
these spheres in the interior are younger bodies of 
the same kind. One of these little cells buds by the 
process of cell-multiplication, and forms a little group 
or cluster; that group becomes a larger mass, and that 
mass, still with the cells closely packed together, 
forms a sphere winch may often be seen revolving 
in the interior of the parent sphere. This, again, is 
not a process of sexual generation, but of gemma¬ 
tion. There is a distinct process of sexual genera¬ 
tion, into which time does not permit of my entering 
to-night. . The parent sphere bursts and sets free 
the contained globes ; and each of these is changed, 
by the formation of a sort of glassy, transparent 
sphere, winch developes itself between the separate 
green cells, from a green opaque sphere into a large 
transparent sphere. Here are representations of a 
number of different forms of this low tribe of plants, 
all distinguished by their red or green colour. You 
may ask how do we know that they are plants ? 
W e find that they decompose carbonic acid under 
the influence of sunlight. The great distinction 
which separates them from the Animalcules which 
they much resemble, is that all true Animalcules feed 
upon other animalcules or upon plants. By this 
distinction we can draw the line pretty sharply except 
in such perplexing cases as that of the fungi, which 
seem to unite the attributes of both kingdoms. 
To give you an illustration of the dependence of 
one kingdom upon the other, I may mention a cir¬ 
cumstance that happened to myself some twenty-five 
years ago. I was then living in the neighbourhood 
of Stoke Newington, and attached to the house in 
which I was residing there was a cistern that I 
could look in upon from my staircase window; it 
was quite open at the top and was filled with rain 
water. This cistern had become foul from leaves 
dropping into it, and early in the summer it had 
been cleaned out. A short time afterwards it was 
filled by a heavy thunderstorm, and in a few days, 
going up and down stairs, I noticed that it had a green 
scum upon the surface, and that this green scum 
came to the surface when the sun was shining upon 
it, but that at other times it was not to be seen. 
On examining some of this, I found it to consist of 
minute separate cells, with a couple of little tails, so 
to speak, which were long cilia, and these were in ac¬ 
tive motion. Now at that time the doctrine of Eliren- 
berg had undisputed sway, and not one of us young 
naturalists would venture to question the dicta of so 
great a man. I myself, however, in my own mind 
had come to entertain a very strong opinion, indeed, 
that these must be Plants, notwithstanding their 
active motion. And a very curious circumstance 
followed, which illustrated the relation of the Vege¬ 
table to the Animal kingdom remarkably well. There 
soon appeared in the cistern a quantity of Wheel 
Animalcules, creatures of extremely high organiza¬ 
tion in comparison with some of the lower forms. 
They fed most greedily upon these little plants; and 
it w r as, in fact, a great amusement to myself and 
friends to take out a few of these wheel animalcules, 
keep them in pure water for a day or two, to starve 
them, and then to put in a drop of water from the 
scum of the cistern loaded with these green cells. 
The eagerness with which they gulped it down was 
something only to be paralleled in recent times by 
the eagerness of the starving population of Paris 
when food was supplied to them. Here then you 
see, first the Inorganic material,—the water,—con¬ 
tained in a clean cistern, filled up at once by a sudden 
shower; from the oxygen and hydrogen of the water, 
and from the carbonic acid of the air, and from the 
minute quantity of nitrogen contained in the am¬ 
monia which is always found in rain water, the 
plant manufactured its materials, so to speak. The 
germ of the Plant, conveyed no doubt by the wind, 
or brought down by the rain, manufactured the ma¬ 
terials, and developed into this enormous mass of 
vegetation. When that mass of vegetation had been 
produced, then the Wheel Animalcules, also brought 
by the wind,—for they are capable of being dried up 
completely, not only the eggs but the wheel ani¬ 
malcules themselves being capable of surviving the 
most complete desiccation,—dropped into the cistern, 
and found such a copious store of food and also of 
warmth, that they developed themselves very rapidly, 
and both by gemmation and by the production of 
eggs would multiply at an extraordinary rate After 
a time, in fact, they seem to have killed out the 
plants upon which they lived, for I found that both 
plants and animalcules underwent a rapid diminu¬ 
tion, so that in about a month afterwards they were 
scarcely to be found. 
Before leaving this last tribe of plants I would 
mention to you that we now include in that group of 
lowest plants, the Protopliytes, tlios'e very beautiful 
forms which are known as the Diatomacece. These 
