556 BIOLOGY OF THE PROTOZOA 



tissues to mice, the young stages and their development are now 

 known. Observations made by this method of study, particularly 

 by Erdmann (1910, a, b, c, and 1914), and by Crawley (1914 and 

 1916) and Marullaz (1920) permit of a tentative life history of 

 S. muris as follows: 



Infection occurs by eating infected tissues, or, as Negre (1907) 

 showed, by eating contaminated feces. The germs, regarded by 

 Erdmann (1914) as sporozoites, enter the epithelial cells within an 

 hour to an hour and a half (Crawley and Marullaz). Here, accord- 

 ing to Crawley (1914 and 1916), they develop directly into gameto- 

 cytes which are sexually differentiated. The microgametocytes 

 become practically all nucleus the chromatin of which is distributed 

 in groups of granules about the periphery; each group forms a 

 single microgamete, the spermatozoids being arranged about the 

 periphery very much like the microgametes of a coccidian. The 

 macrogametocytes retain most of their cytoplasm and become 

 macrogametes. The latter are fertilized by a microgamete. The 

 zygotes then give rise to a large number of products (the sporoblasts 

 of Erdmann) which may enter the musculature, or may possibly 

 pass out with the feces (Crawley). Here there is a gap in the 

 accounts of the life history but ultimately the muscles are invaded 

 and asexual multiplication results in a number of sporozoites 

 (Erdmann) groups of which are massed together and kept in place 

 by membranes formed by the host. Upon reinfection these develop 

 again to gametocytes. 



It is evident that if this account of the life cycle, the important 

 sexual phases of which are supplied by Crawley, is confirmed by 

 further studies, the Sarcosporidia should not be retained in the 

 Cnidosporidia but, as Crawley suggests, should be placed with the 

 Coccidiomorpha. Until such confirmation is forthcoming the older 

 arrangement is retained. 



Sub-phylum SPOROZOA Letckart. 



Class I. TELOSPORIDIA Schaudinn 

 Sub-class 1. Gregarinina (Gregarinae Doflein) 

 Order 1. Eugregarixida Doflein 

 Sub-order 1. Haplocyta Lankester 

 Family 1. Monocystidae Stein 

 Family 2. Zygocystidae Bhatia 

 Family 3. Diplocystidae Bhatia 

 Family 4. Schaudinnellidae Bhatia 

 Family 5. Rhynchocystidae Bhatia 

 Family 6. Stomatophoridae Bhatia 

 Family 7. Aikinetocystidae Bhatia 

 Family 8. Syncystidae Bhatia 

 Family 9. Ganymedidae J. Huxley 

 Family 10. Urosporidue Woodcock 

 Family 11. Lecvdinidae Kamm 

 Family 12. Allantocystidae Bhatia 



