GREGARINA—COCCIDIUM SCHUBERGI 103 
locomotor processes, “mouth,” and contractile vacuoles, 
as well as the thickness of the cuticle and the general 
passivity, with the parasitic habit of the Gregarines. It is 
not clearly understood how these and other intestinal 
parasites have become habituated to resist the action of 
digestive juices. 
Life history.—The young Gregarine is 
parasitic in one of the lining cells of the 
gut; it grows, and, leaving the cell, re- 
mains for a time still attached to it by 
the cap (Fig. 45, a, 4,c); later this is cast 
off, and the individual becomes free in the 
gut, while still increasing in size. Two or 
more individuals attach themselves together 
end to end, but the meaning of this is 
obscure. Encystation occurs, involving a 
single unit or two together. ‘The details 
of spore-formation are similar to those in 
Monocystis. All the protoplasm is not always 
used up in forming the spores, but a residue 
may remain, which forms a network of 
threads supporting the spores. The cyst is 
sometimes (as in G. blattarum) complex, , 
with “ducts” serving for the exit of the 
spores, each of which is surrounded by a = - Bnd 
firm case. Eventually the cyst bursts, the ect Sieh 
spore-cases are liberated, and from within of Gregarines, 
each of these eight spores emerge to be- —After Fren- 
come cellular parasites. The adult of G. el. 
(Porospora) gigantea is sometimes three- 
quarters of an inch in length—enormous for a Protozoon. 
Ninth Type of Protozoa-—-CocciD1UM SCHUBERGI 
Coccidia are intracellular parasitic Sporozoa, attacking 
mainly the epithelial cells of the gut or associated organs. 
They are found chiefly in insects, myriopods, molluscs, and 
vertebrates. 
Coccidium schubergt infests the intestinal epithelium of 
the centipede Lithobius forficatus. The adult is a minute 
