IV. SPOROZOA: OREGARINA. 



213 



Class IV. Sporozoa. 



Under the name Sporozoa are united several groups of Protozoa 

 which, while they differ much in structure, have much in common 

 in life and development. They are parasites in Metazoa, many of 

 them in the cells themselves, causing their degeneration (Cytospo- 



FIG. 154. Sporozoa. -4, cyst of Clepsidrina with sporoducts; B, Clepsidrina, two indi- 

 viduals (after Schneider); C, Eimeriafalcifonnis, from mouse; >, same, falciform 

 embryos: JK, Hoplorhynchus dujnrdinii^ from Litkobius; F, Gregarina atgantea. from 

 lobster; Cr, Sarcocystis miescheri, from pig; H, Myxidium (after Th6olan); I,Rhopa- 

 locephalus, alleged cause of cancer (after Korotneff). 



ridae). They take no solid food, but are nourished by fluid mate- 

 rial absorbed through the whole surface. In reproduction they 

 form a large number of l sporoblasts/ which when enveloped with 

 a membrane are called ' spores/ the contents of which usually 

 break up into several small bodies or ' sporozoites/ The sporozo- 

 ites for their development must leave the host. The resemblances 

 to the Rhizopods (Mycetozoa) are unmistakable, especially those 

 Sporozoa which have pseudopodia for much of their life. 



Order I. Gregarina. 



The typical and longest known sporozoa are the Gregarines, 

 parasites of oval or thread-like form (recalling round worms), 

 usually somewhat flattened, which so far have only been found in 

 invertebrates, where they live in the intestine or gonads, more 

 rarely in the body cavity. The protoplasm (fig. 155, /) is sepa- 

 rated more sharply than in other Protozoa into a clear ectosarc 

 (elc) and a granular entosarc (en). The ectosarc is covered by 

 a cuticle (not always easily seen, but frequently with a double con- 

 tour) (cu), which must be permeable by fluid food, for no cyto- 

 stome exists. In many (perhaps all) there is a double striping 

 of the body, a longitudinal recognizable by furrows on the outer 

 surface and hence cuticular, and a transverse marking in the 



