243] STUDIES ON GREGARINES —WATSON 33 



each with a portion of the zygote nucleus. The resulting body is an oc- 

 tozoie spore. The spores are liberated from the cyst through spore ducts 

 which are formed from the residual protoplasm of the cyst. They are 

 scattered over the grass and ground by the wind and rain and are eaten 

 by some host along with its food. Parasitism is thus accidental. The 

 spores upon reaching the alimentary canal of the host are acted upon by 

 the digestive juices and the spore wall absorbed. Upon the disappear- 

 ance of the wall, the eight sporozoites are set free and the life history 

 starts on the same cycle again. 



THE QUESTION OP SPORONT MATURITY 



The question may be raised in connection with the development of 

 the sporonts and cysts : Can one detect a sporont which is fully mature 

 and ready for cyst formation ? After many months of observation upon 

 a number of species of several genera, I have come to the conclusion that 

 full maturity can be detected and the imminent cyst formation pre- 

 dicted. In a genus like Gregarina, in which the association of sporonts 

 is a characteristic feature, the fact that specimens are in associations of 

 two does not indicate that the sporonts are mature, for associations are 

 often formed early in sporont life while the animals are very small and 

 obviously immature. In fact many sporonts are seen in association 

 which are much smaller than some cephalonts of the same species free 

 in the intestine. The fact that sporonts are linked together in twos is 

 not an indication of maturity. 



Density of the animals is often a criterion of maturity but not one 

 upon which to depend. Cephalonts are transparent or nearly so; the 

 small sporonts are but slightly opaque and opacity increases steadily 

 with age, the oldest in many species being very dense and practically 

 black in transmitted light. If, however, a host is starved a few days be- 

 fore being opened, the parasites are likewise starved and become more 

 or less transparent. 



Size increases with age and only the large individuals in any case 

 inay be expected soon to form cysts. 



While no one of these three characteristics can be used as a test of 

 maturity of the sporonts, an association of large sporonts in which the 

 individuals are well filled with protoplasmic granules and hence opaque, 

 indicates without doubt that the sporont is mature. 



Movement of such an association is no longer the active motion of 

 translation; the sporonts have become sluggish and tend to revolve. 

 AVhen the revolution becomes fairly well established, it takes a spiral 

 form and gives place to rotation. The animals finally become a compact 

 spherical mass with a cyst wall which has been secreted during rotation. 

 The sporonts are now in position to reproduce themselves. 



