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presence of starch and cellulose can be successively demon- 
strated. Thus, then, the chemical composition, as well as the 
structure and mode of division of these yellow cells, are those of 
unicellular alg, and I accordingly propose the generic name of 
Fhilozoon, and distinguish four species, differing slightly in 
size, colour, mode of division, behaviour wlth reagents, &c., 
for which the name of P. radiolarum, P. siphonaphorum, P. 
actiniarum, and P. medusarum, according to their habitat, may 
be conveniently adopted, It now remains to inquire what is 
their mode of life, and what their function. 
I next exposed a quantity of Radiolarians (chiefly Co//ozoum) 
to sunshine, and was deiighted to find them soon studded with 
tiny gas-bubbles. Though it was not possible to obtain enough 
for a quantitative analysis, I was able to satisfy myself that the 
gas was not absorbed by caustic potash, but was partly taken up 
by pyrogallic acid, that is to say, that little or no carbonic acid 
was present, but that a fair amount of oxygen was present, 
diluted of course by nitrogen. The exposure of a shoal of the 
beautiful blue pelagic Siphonophore, Vé/e//a, for a few hours, 
enabled me to collect a large quantity of gas, which yielded 
from 24 to 25 per cent. of oxygen, that subsequently squeezed 
out from the interior of the chambered cartilaginous float, giving 
only 5 percent. But the most startling result was obtained by 
the exposure of the common Anthea cereus, which yielded great 
quantities of gas containing on an average from 32 to 38 per 
per cent, of oxygen. 
At first sight it might seem impossible to reconcile this copious 
evolution of oxygen with the completely negative results ob- 
tained from the same animal by so careful an ex; erimenter as 
Krukenberg, yet the difficulty is more apparent than real. After 
considerable difficulty I was able to obtain a large and beautiful 
specimen of Anthea cereus, var. smaragdina, which is a far more 
beautiful green than that with which 1 had been before operat- 
ing—the dingy brownish-olive variety, s/mosa. The former 
owes its colour to a green pigment diffused chiefly through the 
ectoderm, but has comparatively few alge in its endoderm ; 
while in the latter the pigment is present in much smaller quan- 
tity: but the endoderm cells are crowded by alge. An ordinary 
specimen of f/umosa was also taken, and the two were placed 
in similar yessels side by side, and exposed to full sunshine, by 
afternoon the specimen of flumosa had yielded gas enough for 
an analysis, while the larger and finer sszaragdina had scarcely 
produced a bubble. Two varieties of Certactis aurantiaca, one 
with, the other without, yellow cells, were next exposed, with a 
precisely similar result. The complete dependence of the evo- 
lution of oxygen upon the presence of algz, and its complete 
independence of the pigment proper to the animal was still 
farther demonstrated by exposing as many as possible of those 
anemones known to contain yellow cells (Azptasia chameleon, 
Helianthus troglodytes, &c.) side by side with a large number of 
forms from which these are absent (Actinia mesembryanthemum, 
Sagastia parasitica, Cerianthus, &c.). The former never failed 
to yield abundant gas rich in oxygen, while in the latter series 
not a single bubble ever appeared. 
Thus, then, the colouring matter described as chlorophyll by 
Lankester has really been mainly derived from that of the endo- 
dermal alge of the variety f/mosa, which predominates at 
Naples; while the Anthea-green of Krukenberg must mainly 
consist of the green pigment of the ectoderm, since the Trieste 
variety evidently does not contain alge in any great quantity. 
But since the Naples variety contains a certain amount of 
ordinary green pigment, and since the Trieste variety is tolerably 
sure to contain some algze, both spectroscopists have been operating 
on a mixture of two wholly distinct pigments—diatom-yellow 
and anthea-green. 
But what is the physiological relationship of the plants and 
animal thus so curiously and intimately associated ? Every one 
knows that all the colourless cells of a plant share the starch 
formed by the green cells ; and it seems impossible to doubt that 
the endoderm cell or the Radiolarian, which actually incloses the 
vegetable cell, must similarly profit by its labours. In other 
words, when the vegetable cell dissolves its own starch, some 
must needs pass out by osmose into the surrounding animal cell ; 
nor must it be forgotten that the latter possesses abundance of 
amylolytic ferment. Then, too, the Phi/ozoon is subservient in 
another way to the nutritive function of the animal, for after its 
short life it dies and is digested; the yellow bodies supposed by 
various observers to be developing cells being nothing but dead 
algee in progress of solution and disappearance. 
Again, the animal cell is constantly producing carbonic acid 
and nitrogenous waste, but these are the first necessities of life 
to our alga, which removes them, so performing an intracellular 
renal function, and of course reaping an abundant reward, as its 
rapid rate of multiplication shows. 
Nor do the services of the P4ilozoon end here; for during 
sunlight it is constantly evolving nascent oxygen directly into the 
surrounding animal protoplasm, and thus we have actually 
foreign chlorophyll performing the respiratory function of native 
hemoglobin! And the resemblance becomes closer when we 
bear in mind that hemoglobin sometimes lies as a stationary 
deposit in certain tissues, like the tongue muscles of certain 
molluscs, or the nerve cord of Aphrodite and Nemerteans. ‘ 
The importance of this respiratory function is best seen by 
comparing as specimens the common red and white Gorgonia, 
which are usually considered as being mere varieties of the same 
species, G. verrucosa. The red variety is absolutely free from 
Philozoon, which could not exist in such deeply-coloured light, 
while the white variety, which I am inclined to think is usually the 
larger and better grown of the two, is perfectly crammed. Justas 
with the anemones above referred to, the red variety evolves no 
oxygen in sunlight, while the white yields an abundance, and we 
have thus two widely contrasted physiological varieties, as I may 
call them, without the least morphological difference The white 
specimen, placed in spirit, yields a strong solution of chlorophyll: 
the red, again, yields a red solution, which was at once recog- 
nised as being tetronerythrin by my friend M. Merejkowsky, 
who was at the same time investigating the distribution and 
properties of that remarkable pigment, so widely distributed in 
the animal kingdom. This substance, which was first discovered 
in the red spots which decorate the heads of certain birds, has 
recently been shown by Krukenberg to be one of the most im- 
portant of the colouring matter of sponges, while Merej- 
kowsky now finds it in fishes and in almost all classes of 
invertebrate animals. It has been strongly suspected to be an 
oxygen-carrying pigment, an idea to which the present observa- 
tion seems to me to yield considerable support. It is moreover 
readily bleached by light, another analogy to chlorophyll, as we 
know from Pringsheim’s researches. 
When one exposes an aquarium full of A thea to sunlight, the 
creatures, hitherto almost motionless, begin to wave their arms, 
as if pleasantly stimulated by the oxygen which is being deve- 
loped in their tissues, Specimens which I kept exposed to direct 
sunshine for days together in a shallow vessel placed on a white 
slab, soon acquired a dark, unhealthy hue, as if being oxygenated 
too rapidly, although I protected them from any undue rise of 
temperature by keeping up a flow of cold water. So, too, I 
found that Radiolarians were killed by a day’s exposure to sun- 
shine, even in cool water, and it is to the need for escaping this 
too rapid oxidation that I ascribe their remarkable habit of 
leaving the surface and sinking into deep water early in the day. 
It is easy, too, to obtain direct proof of this absorption of a 
great part of the evolved oxygen by the animal tissues through 
which it has to pass. The gas evolved bya green alga (U/wa) 
in sunlight may contain as much as 70 per cent. of oxygen, that 
evolved by brown alge (/aliseris) 45 per cent., that from 
diatoms about 42 per cent. ; that, however, obtained from the 
animals containing Phi/ozoon yielded a very much lower per- 
centage of oxygen, e.g. Velella 24 per cent., white Gorgonia 24 
per cent., Ceriactis 21 per cent, while Anthea, which contains 
most alge, gave from 32 to 38 per cent. This difference is 
naturally to be accounted for by the avidity for oxygen of the 
animal cells. 
Thus, then, for a vegetable cell no more ideal existence can) be 
imagined than that within the body of an animal cell of sufficient 
active vitality to manure it with carbonic acid and nitrogen waste, 
yet of sufficient transparency to allow the free entrance of the 
necessary light. And conversely, for an animal cell there can 
be no more ideal existence than to contain a vegetable cell, con- 
stantly removing its waste products supplying it with oxygen 
and starch, and being digestible after death. For our present 
knowledge of the power of intracellular digestion possessed by 
the endoderm cells of the lower invertebrates removes all diff- 
culties both as to the mode of entrance of the algze, and its fate 
when dead. In short, we have here the relation of the animal 
and the vegetable world reduced to the simplest and closest 
conceivable form. 
It must be by this time sufficiently obvious that this remarkable 
association of plant and animal is by no means to be termed a 
case of parasitism, If so, the animals so infested would be 
weakened, whereas their exceptional success in the struggle for 
[Fan. 26, 1882 . 
a a en, ee 
