GENERAL PHYSIOLOGY 



201 



Specific structural adaptations, useful in methods of food-getting, 

 are characteristic. Haustoria-like processes, derived from the 

 epimerites of gregarines, in some cases extend deeply in the tissue 

 cell {Stylorhynchus longicollis, Echinomera hispida, Pyxinia moebiuszi, 

 etc., Fig. 103). The coccidian Caryotropha mesnili, according to 

 Siedlecki, shows a significant relation between the nucleus of the 

 host cell and that of the parasite. This organism is a parasite in 

 the spermatozoa of the annelid Polymnia nebvlosa where the sperm 

 cells are aggregated in bundles in the characteristic annelid fashion, 

 usually about a feeding mass or blastophore. The parasite gets 

 into such a cell as an agamete or sporozoite, one only of the bundle, 



Fig. 103. — Food-getting adaptations of Sporozoa. 1, Pyxinia moebiuszi with epi- 

 merite deeply insunk in the epithelial host cell (after Leger and Dubosq) ; 2, Caryo- 

 tropha mesnili with an intracellular canal from the nucleus of the host cell (ti). (After 

 Siedlecki.) 



as a rule, being infected, and as it grows the nucleus of the cell is 

 displaced to one side and the cell loses its characteristic structure, 

 becoming hypertrophied and distorted (Fig. 103, 2). Not only the 

 infected cell but all the other cells of the spermatogonia bundle are 

 affected, and none of them continues the normal development, but 

 they become arranged like epithelial cells about the hypertrophied 

 infected cell. 



The specific effect of the young Caryotropha on the infected cell 

 consists not only of the enlargement of that cell, but of a definite 

 feeding mechanism by which the parasite is supplied with food. 

 That the nucleus is a center of constructive metabolic changes is 

 well assured at the present day, and the conditions in these para- 



