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. majoris. —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. danilezvskyi (Halteridium). — Occurs 
almost exclusively in the blood of ‘ passerine 5 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. 
