462 BIOLOGY OF THE PROTOZOA 



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 imi)ortant 

 sexual phases of w^hich are supplied by Crawley, is confirmed by 

 further studies, the Sarcosporidia should not be retained in the 

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

 Coccidiomorpha. Until such confirmation is forthcoming the older 

 arrangement is retained. 



III. QUESTIONABLE PROTOZOA. CHLAMYDOZOA. 



The term Chlamydozoa was applied by Prowazek (1907) to intra- 

 cellular structures found in human tissues in connection with certain 

 diseases, and regarded by him, as well as by many others, as Pro- 

 tozoa. Others, pathologists particularly, looked upon them as 

 degeneration products of the diseased cells, or as artefacts due to 

 technical processes, and the\' are still more commonly referred to 

 not by the generic and specific names which they have received, 

 but by the names of the men who first studied them. Thus the 

 " Guarnieri bodies" refer to the characteristic cell inclusions of 

 variola and \'accinia which were named by Guarnieri (1892) Cyto- 

 ryctes mriolw and Cytoryctes vaccinioe; the "Negri bodies" similarly 

 refer to the inclusions in nerve cells of animals suffering from 

 hydrophobia and named by Williams and Lowden (1906) Neuro- 

 ryctes hydrophohioe (Fig. 193). More or less similar inclusions of 

 diseased cells have been described from moUuscum contagiosum 

 (Prowazek) trachoma (Prowazek and Halberstf^dter) , epitheliosis 

 desqaamativa (Leber and Prowazek), swine pest (Uhlenhuth), 

 sprue (Castellani), bird-pox, sheep-pox, verruga peruviana, herpes 

 (zoster, genitalis, and febrilis). The latter were regarded by 



