STRUCTURAL MODIFICATIONS OF PROTOZOAN PARASITES 177 



lodgement in the cell nucleus; such caryozoic forms are only specially 

 adapted cytozoic types, but their habitat is always the same (Cyclospora 

 caryolytica, Nucleophaga amebea, and in part Cytoryctes variola, and 

 others); others, finally, are hematozoic, living in the blood (trypano- 

 soma, plasmodium, hemoproteus, etc.). In many cases there may 

 be modifications of these modes of life, or combinations of two or 

 more. Thus, plasmodium may be hematozoic, cytozoic, enterozoic, 

 and coelozoic during some period of its life history in the mosquito or in 

 the blood, and the terms are too indefinite to be employed in any way 

 save for purposes of description. In many cases, as, for example, in 

 gregarines, the young phases are cytozoic, the adult coelozoic or entero- 



Fio. 73 



Pyxinia mobiuszi, from Liihe. (After Lfeger and Dubosq.) 



zoic, and in such cases the young forms may have special organs 

 serving for attachment or for feeding, and as they grow to maturity 

 such processes may remain in the host cell, serving for attachment, or 

 as haustoria for the absorption of nutriment. Sometimes these are 

 great prolongations at one end of the cell, as in Pyxinia mobiuszi 

 (Fig. 73) ; again, many such processes may be present, as in Ptero- 

 cephalus yiardi, or in ophryocystis (Fig. 80). When the organism is 

 sexually mature or ready for reproduction the attaching processes are 

 discarded and left behind in the epithelial cell of the host, while the 

 freed parasite lies in the lumen of the organ. Such attached gregarines 

 are known as cephalonts, and the detached forms as sporonts. The 

 cephalonts may be variously ornamented, according as the attaching 



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