66 
PROFESSOR E. RAY LANKESTER. 
also were again obtained from a tube which contained at first 
abundant colonies, such as that drawn in PI. VII, fig. 24. 
After a week’s interval the colonies were found to have broken 
up into single individuals (that is, individuals containing each 
but one chlorophyll- corpuscle), and a week later many were 
found to have increased greatly in size, and to have become 
enclosed in a cyst. The cyst appears to consist of a resisting 
membrane, which is produced on the surface of the protoplasm, 
and actually extends for some distance along the filamentous 
pseudopodia. As the deposit increases in amount the pseudo- 
podia are withdrawn, and finally there results a spherical cyst 
provided with numerous truncated processes on its surface, 
resembling the short spines of a horse-chestnut fruit. In 
such cysts the protoplasm and its chlorophyll body may be 
observed in various conditions. I have most frequently found 
the protoplasm shrunken, so as to be completely detached 
internally from the cyst-membrane (figs. 2 and 3). At the 
same time, in such specimens there was no appearance of any 
differentiated chlorophyll-corpuscle, but the whole of the pro- 
toplasm was uniformly coloured green. Occasionally I have 
seen the whole contained mass in a state of granular dis- 
integration (fig. 1). On the other hand, the cysts sometimes 
show (figs. 4, 6) a disposition of the protoplasm with vacuole 
and two chlorophyll-coloured masses not dissimilar to that of 
the un-encysted Actinophryd form (fig. 7). 
I am not able to state what is the exact position of the 
encysted condition in the life-history of Archerina. 
I do not know whether the Actinophrvd-forms, such as 
figs. 7 and 12, are just about to be encysted, or whether they 
have just escaped from the encysted condition. The latter 
seems to me to be the more probable. 
3. Vegetative Condition — Tetraschistic Colonies (figs. 20,21, 
22.) — Alongside of the Actinophrvd-forms of Archerina occur 
very numerous specimens in which the protoplasm is no longer so 
definitely disposed in the form of a central sphere and clean- 
cut radiating filaments, but is irregular in shape with occasional 
lobose projections, whilst groups of radiating filaments are 
