LIFE HISTORIES OF THE PROTOZOA. 745 
A. Self-division then begins as at C, the nucleus doubling itself, 
until at Da and Db, we have as a result two individuals, 
In Pelomyxa, a higher form than Amoeba, we have according to 
Greef a production of ciliated zoospores. This form, described 
Fig, 134. 
by Greef under the name of Pel- 
omyza palustris (Fig. 184, A, a, 
clear portion ; b diatoms enclosed 
in the body mass), lives in the 
mud at the bottom of pools, and 
When first seen resembles little 
dark balls of mud -04—-05. inch 
in diameter. The body mass 
contains numerous vacuoles filled 
With water, and numbers of nu- 
clei and spicules. These nuclei 
and spicules have a dancing mo- 
tion, like the ordinary Brownian Pelomyxa palustris. 
There are also numerous hyaline, oval 
movements of molecules. 
or rounded bodies which Greef calls ‘‘ shining bodies,” and which 
originate from the nuclei. They increase by division within the 
body-mass of the Pelomyxa, becoming Ameeba-like bodies (Fig. 
134, B, n nucleus, ¢ contractile vesicle) which issue in great num- 
bers from the parent-mass. These Ameeboid forms gradually pass 
into flagellate zoospores (Fig. 134, C) with a nucleus and con- 
tractile vesicle. It thus seems that the zoospores of this Rhizopod 
are produced without the animal becoming encysted. 
As regards the development of Actinophrys and the allied spiny 
forms, Greef thinks that besides being formed by direct self-division, 
there is a resting or encysted stage. ‘‘ The latter consists in the 
withdrawal of the sarcode body-mass from the inner boundary 
formed by the union of the bases of the radial spines, leaving a 
rather wide empty border, and its becoming invested by a double * 
coat, viz., a firm inner one, when empty, dotted, as if perforated, 
and an outer hyaline one.” 
According to Schneider, Actinophrys Eichhornii undergoes di- 
Vision ; the central mass divides twice or thrice. Then the alveo- 
lar cortical layer disappears, and each mass resulting from the 
self-division becomes encysted. This process is undergone in two 
days. It remains encysted through the winter until the beginning 
