LIFE HISTORIES OF THE PROTOZOA. 739 
more or less considerable part of its body. Then the posterior 
part of the body may be often seen to throw itself out laterally by 
a brusque and instantaneous movement, forming an angle with the 
anterior part. 3. Owing to the contractions of the body the gran- 
ules within the body move about. 
Development. The history of Gregarina has been worked out 
by Siebold, Stein, Lieberkuhn, and more recently by E. Van Bene- 
den. The course of development is as follows: the worm-like 
adult, G. gigantea (Fig. 131, K, n nucleus, L, two individuals nat- 
ural size), which is common in lobsters on the European coast in 
May, June and August, becomes encysted,in September in the 
walls of the rectum of the lobster, the cysts (Fig. 131, A) appear- 
ing like “Tittle white grains of the size of the head of a small 
pin.” When thus encysted the animal loses its nucleus, and the 
granular contents of the cyst divide into two masses (B), like the 
beginning of the segmentation of the yolk of the higher animals. 
The next step is not figured by Van Beneden, and we therefore 
introduce some figures from Lieberkubn which show how the gran- 
ular mass breaks up into zoospores (called by authors “ pseudo- 
havicelle,” and by Lieberkuhn ‘‘ psorosperms ”) with hard shells. 
After the disappearance of the nucleus and vesicle, and when the 
encysted portion has become a homogeneous granular mass, this 
~ mass divides into a number of rounded balls (Fig. 131, C). 
- These balls consist of fine granules, which are the zoospores in 
their first stage (Fig. 131, N). They then become spindle-shaped 
_ (O), and fill the cyst (Fig. 131, M), the balls having meanwhile 
_ disappeared. From these zoospores are expelled Ameba-like 
masses of albumen (D, E) which, as Van Beneden remarks, ex- 
actly resemble the Protameba already described. This moner- 
like being, without a nucleus, is the young Gregarina. : 
` But soon the Amoeba characters arise. The moner-like young 
(Fig. 131, D, E) now undergoes a further change. Its outer por- 
n becomes a thick layer of a brilliant, perfectly homogeneous 
_ protoplasm, entirely free from granules, which surrounds the cen- 
_ al granular contents of the eytode (Heckel) or non-nucleated 
= cell. This is the Amæba stage of the young Gregarina, the body, 
4s in the Ameba, consisting of a clear cortical and granular me- 
:  dullary or central portion. 
~ The next step is the appearance of two arm-like projections 
(Fig. 131, F); See to the pseudopods of an Amoeba. One 
t 
