ARCHERINA BOLTONI. 
69 
growth as fig. 24 would break up into several hundred indi- 
viduals. Each of these then would slowly attain to the size 
and form of the Actinophryd-phase (fig. 7), the chlorophyll- 
corpuscle partially dividing and spreading itself out as seen in 
figs. 7 , 8, 9, 10, 11. 
Probably such individuals now pass on — if conditions adverse 
to nutrition are continued — into the encysted condition, from 
which they will emerge on the return of conditions favorable 
to nutrition. 
This life-history is hypothetical. It is, however, favoured 
by the fact that specimens of vegetative growths such as fig. 
24, when kept in the moist-chamber for two weeks, first of all 
broke down into individual units consisting of a single 
chlorophyll-corpuscle and some protoplasm, and that later 
many were observed of a large size in the Actinophryd-phase, 
whilst later still on the same slide numerous encysted indi- 
viduals were found which were not previously detected. A 
similar observation was made with regard to the contents of 
a glass tube kept on the table of my laboratory screened from 
the direct sunlight. 
4. Skeleton-colonies. — A very curious characteristic of the 
colonies of Archerina is represented in fig. 18. In exploring a 
slide containing specimens in the early tetraschistic phase 
(such as figs. 20 and 22), one comes across groups of ghost-like 
outlines corresponding to chlorophyll-corpuscles, and their 
radiant filamentous pseudopodia, entirely devoid of any sub- 
stance. They are merely outlines, as though sketched with a 
pencil, very delicate and inconspicuous. Here and there in 
such a ghost-like group one finds a solid chlorophyll-corpuscle 
and attendant protoplasm. 
These strange outline “simulacra” of Archerina-colonies are 
undoubtedly skeletal products of the solid protoplasm, which 
after producing them has withdrawn from them and moved 
into another position. They appear to indicate that the pro- 
toplasm is at this phase of the life-history of Archerina capable 
of producing a pellicle on its surface, comparable to the cyst 
which is produced when encystation takes place ; but instead 
