GREGARINIDA, 29 
viscid fluid holding in suspension rounded granules, among 
which the nucleus rests. This nucleus contains an inner 
vesicle or nucleolus, which strangely disappears and then 
reappears. Van Beneden distinguishes three kinds of mo- 
tions in the Gregarine: 1. They represent a very slow 
movement of translation, in a straight line, and without the 
possibility of distinguishing any contraction of the walls of 
the body which could be considered as the cause of the 
movement. It seems impossible to account for this kind of 
motion. 2. The next kind of movement consists in the 
lateral displacement of every part, taking place suddenly 
and often very violently, from a 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. 38. Owing to the contractions of the body, the gran- 
ules within the body move about. 
The life-history of this Gregarina is as follows : It occurs 
in its normal state in lobsters in May, June, and August, but 
in September becomes encysted in the walls of the rectum of its 
host, the cysts (Fig. 18, 4) appearing like little white grains 
of the size of the head of a small pin. When thus encysted 
the nucleus disappears, 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 intro- 
duce some figures from Lieberkuhn which show how the 
granular mass breaks up into spindle-shaped bodies (called 
by some authors ‘ pseudonavicelle,’’ 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. 18, C’). These balis 
consist of fine granules, which are the spindle-shaped bodies 
in their first stage (Fig. 18, NW). They then become 
spindle-shaped (O) and fill the cyst (Fig. 18, 17), the balls 
having meanwhile disappeared. From these psorosperms 
are expelled amceba-like masses of albumen (D #’), which, 
as Van Beneden remarks, exactly resemble the Protameba 
