HAEMOSPORIDIA 



487 



endothelial cells in addition to erythrocytes of host birds had been 

 observed by Raffaele (1934) and Huff and Bloom (1935). 



As to the nature of development of Plasmodium during the pre- 

 patent period, James and Tate (1938) showed that there occur schiz- 

 onts and schizogonic stages in the endothelial cells of the spleen, 

 heart, liver, lung, and brain of the birds infected b}^ P. gallinaceum 

 (Fig. 226). They suggested the term exo erythrocytic to this schizog- 

 ony in contrast to the well known erythrocytic schizogony. Similar 

 schizogony has further been observed by several investigators in P. 



g h 



Fig. 226. Exoerythrocytic schizogony in avian Plasmodium, a-f, P. 

 gallinaceum in smears from chicks (James and Tate), a, monocyte from 

 lung, infected by 2 young schizonts; b, monocyte from liver, with a grow- 

 ing trinucleate schizont; c, monocyte from lung, with a large multi- 

 nucleate schizont; d, large mature schizont containing many mature mero- 

 zoites, free in lung; e, portion of broken schizont from lung, showing the 

 attached developing merozoites. ( X1660). f, a capillary of brain blocked 

 by 3 large schizonts ( X740). g, h, P. cathemerium in sections of organs of 

 canaries (Porter; X 1900). g, capillary in the brain, showing an endothelial 

 cell infected with a uninucleate and a multinucleate schizont; h, a multi- 

 nucleate schizont and a group of merozoites found in a capillary of heart 

 muscle. 



cathemerium, P. circumflexum, P. nucleophilum and P. relictum. 

 However, these reported exoerythrocytic stages are of varied ap- 

 pearances and their relation to erythrocytic schizogony is still un- 



