ARCHERINA BOLTONI. 
65 
comparison of fig. 25 of the present Plate II with fig. 17 a of 
PL XX, Yol. XXII (1882) of this Journal. 
The chlorophyll-corpuscle of Archerina has accordingly an 
interesting relation to the question which has been raised by 
Brandt, as to the parasitic nature of the chlorophyll-corpuscles 
of Hydra viridis. If the theory is entertained that the latter 
are independent green algae which inhabit the endoderm cells of 
Hydra as parasites, then it would seem necessary to take a 
similar view with regard to the chlorophyll-corpuscle of Arche- 
rina. The Archerina would itself be a very simple non- 
nucleate G-ymnomyxon similar to Vampvrella, which would be 
supposed to be always inhabited and dominated in its movements 
of growth and division by the green algal parasite. With regard 
to such a conception, it may be justly observed that on equally 
valid grounds the nuclei of other Protozoa — and, indeed, of all 
animal and vegetable cells — might be regarded as colourless 
parasites inhabiting non-nucleated corpuscles of protoplasm. 
On the other hand, it would be urged that no independent 
organisms resembling the nuclei of cells are known, and that 
in the absence of any direct evidence of their intrusion from 
external sources into the protoplasm of cells, as well as in view 
of the phenomena of their division and their relation to the 
protoplasm, it is a gratuitous assumption that they have a 
history differing essentially from that of other products of the 
modification of cell-substance. In the same way we urge, in 
reference to the tetra-schistic chlorophyll-corpuscles of both 
Archerina and Hydra viridis, that they do not resemble 
any known unicellular green alga, either in structure or in mode 
of growth, and that there is no reason for attributing to them 
a fanciful origin and history differing essentially from that of 
other coloured corpuscles and such products of the modification 
of cell-substance. 
2. Encysted Form (figs. 1 to 6). — In the earlier gatherings 
sent to me by Mr. Bolton, which contained only a few of the 
vegetating growths of Archerina, and these only in the condition 
of small colonies, with four or eight chlorophyll-corpuscles, 
I found many specimens of large encysted Archerinse. These 
VOL. XXV. NEW SER. E 
