ACTINOPHRYS. gl 
phrys feeds are paralysed when they come in contact with 
the pseudopodia. 
The body consists of ectoplasm and endoplasm. The 
ectoplasm is a thick external layer closely packed with 
large vacuoles, which are non-contractile and contain a 
clear fluid. But food yacuoles are formed as in other 
Protozoa, and there is also: a single contractile vacuole. 
The endoplasm forms the central mass. It is not 
vacuolated, and contains the large, centrally placed nucleus. 
Life history. — 
An Actinophrys may 
withdraw its pseudo- 
podia and divide 
into two, with or 
without the forma- 
tion of a cyst. A 
number of — indi- 
viduals may unite 
for a time by the 
ectoplasm _ alone, 
and separate with- 
out any nuclear 
fusion having taken 
place (plastogamy). 
But Schaudinn has 
described a ttue Fic. 36.—Acténophrys sol (Sun-animalcule). 
Sexual process - After Grenacher. 
which ‘olfers, an > elbagig feed camila; g, coment 
interesting analogy Poni 
to the processes of maturation and fertilisation in the 
higher animals. © : ; 
A number of individuals become joined up in a common 
gelatinous cyst. Each loses its pseudopodia and forms a 
membranous cyst. These cysts become associated in pairs. 
The nucleus of each ‘cyst divides mitotically.and a polar 
body is extruded from each, after which the nucleus 
returns to the resting condition. The cysts now fuse in 
pairs, with complete arid intimate union of their nuclei 
and cell-bodies. The zygote so formed rests for a short 
period, then divides up into two daughter cysts from which 
emerge two new individuals of Actinophrys, 
