253 



are degenerated sporozoits, as they are found within 

 the large sporoblast cysts. We have, however, found 

 them in or about the salivary glands in Myzomyia rossi. 



According to Ed. and Et. Sergent, a mosquito can 

 infect two consecutive birds but not a third. All 

 attempts to obtain infection by the progeny of infected 

 mosquitoes failed. 



The following two parasites resemble Proteosoma : 



2. H. major is. In the great tit (Parus major}, 

 the number of merozoits is sixteen. 



3. H. vaughani. In an American blackbird 

 (Merula migratoria) with only four merozoits. 



4. H. danilewskyi (Halteridium). Occurs 

 almost exclusively in the blood of ' passerine ' birds. 

 Pigeons are very commonly infected, also sparrows, 

 finches, parrots, Java sparrows, and many other birds. 

 It remains to be seen whether there exists one or very 

 many species. 



The parasite is characterised by its peculiar 

 curved halter shape, embracing the oval nucleus of 

 the red cell without any displacement of the latter 

 (Fig. 75). Young forms are occasionally seen, but 

 whether these are young sexual or asexual forms is 

 not determined. Segmenting forms and those cor- 

 responding to an asexual cycle, as in proteosoma, are 

 unknown.* 



Two varieties of parasites, the male and female 

 gametes, are easily distinguished. 



(i) Note that the male gamete has a clear hyaline 

 appearance. On staining (use undiluted Romanowsky) 

 a central large mass of chromatin is distinguished, 

 while the protoplasm is a faint blue. Five or more 

 oval pigment grains are placed generally at either 

 extremity. 



* They have recently been described in the lung blood. 



