62 
PROFESSOR E. RAT LANKESTEE. 
Occurrence. — Archerina occurs in great numbers in pond- 
water associated with Desmids and other minute chlorophyll- 
bearing algae. Its spherical chlorophyll-corpuscles may at 
first be mistaken for those of such microscopic plants ; but a 
little attention is sufficient to enable one to detect around 
many of the bright-green spheres or groups of spheres a halo 
of radiant protoplasm, frequently in the form of very long and 
stiff filaments. Once recognised, it is not difficult to distin- 
guish Archerina in its various phases of growth and multipli- 
cation from its associates. 
Structure and Life-history. — 1. Actinophryd-form,fig. 7. 
— The abundance in which Archerina occurs in the material 
sent to me by Mr. Bolton has enabled me to trace it in several 
phases of growth. The most convenient of these to commence 
with is that represented in PI. VII, figs. 7 and 13. We have 
here a spherical body xoVof^ of an inch in diameter, consisting 
of a sharply outlined mass of refringent protoplasm, from the 
surface of which radiate a number of very delicate but stiff 
filaments, some of them four times as long as the diameter of 
the sphere and tapering from the base towards the extremity. 
There are in such a specimen about fifty of these filamentous 
“ pseudopodia, ” more or less. The base of each filament is 
relatively broad, and appears to join without penetrating the 
surface of the sphere. In such specimens I could detect no 
membrane or pellicle on the surface of the sphere or its pseudo- 
podia. The pseudopodia are motionless, and did not exhibit 
any streaming of granules such as is seen in Actinosphserium. 
Within the spherical body is usually one lai’ge spherical 
vacuole (fig. 7), but sometimes there are more, and they may 
be of various sizes (figs. 8 to 12). Sometimes the whole of 
the protoplasm of the spherical body appears of a bright green 
colour (fig. 8), but on causing the organism to roll over one 
finds that the green colour is limited to two masses, which may 
be united on one face of the sphere though separated more 
deeply. 
Usually the green colour, in the particular phase of 
Archerina now under description, appears in the form of two 
