THE SPOROZOA 



269 



preceding ; merozoites disposed in two groups, connected by the residual 

 body. Gametocytes bean -shaped. One species, H. danilewskyi (Gr. et 

 Fel.), parasitic upon various common birds (Fig. 79). Intermediate host 

 not known. [The two forms of endoglobular parasites found in the blood 

 of birds, Haemoproteus and Halteridium, are easily distinguished in all 

 but the very youngest stages. Haemoproteus has an irregular, more or 

 less compact form, occupies the centre of the corpuscle, and pushes the 

 nucleus to one side, often compressing or deforming it (Fig. 78) ; 

 sporulation takes place in the peripheral circulation. Halteridium, on 

 the other hand, grows in a characteristic manner so as to resemble a 

 halter in form, surrounding the nucleus, which is scarcely or not at all 

 displaced (Fig. 79) ; it sporulates only in the internal organs, especially 

 in the spleen and the bone-marrow.] Genus 8. Piroplasma, Patton, 

 1895 1 (synn.Pi/rosoma, Smith et Kil borne, 1893; Apiosoma, Wandol- 

 leck, 1895 ; Babesia, Starcovici, 1893). Trophozoites amoeboid, ovoid, 



k. 



FIG. 80. 



Development and schizogony of Piroplasma bigeminum in the blood-corpuscle of the ox. a, 

 youngest form. 6, slightly older, c and d, division of the nucleus, e and /, division of the 

 body of the parasite, g, h, i, j, various forms of the twin parasite, k and I, doubly-infected 

 corpuscles. (After Laveran and Nicolle.) 



or pear-shaped ; schizogony by simple fission. Sexual cycle and sporo- 

 gony unknown. Type-species P. bigeminum (Sm. et K), parasite of Texas 

 cattle-fever (Fig. 80) ; the disease is known to be transmitted by the 

 bites of ticks (see above), but the phases of the parasite in the intermediate 

 host have not been studied. Hunt [69] has found crescents in the blood 

 of cattle, and has observed their change into a spheroidal shape, but 

 while comparing these bodies to the crescents of the malarial parasites, 

 he at the same time regards them as a form of sporulating body producing 



1 The nomenclature of the parasite of Texas-fever and its congeners is in a very 

 confused state. The generic name Pyrosoma given to it by Smith and Kilborne in 

 1893, being preoccupied for the well-known Ascidiau genus, was altered to Piro- 

 plasma by Patton in 1895 (not 1885, as wrongly stated by Labbe [4]), and in the 

 same year Wandolleck gave it the name Apiosoma, Avhich, however, had previously been 

 given by Blanchard in 1885 to a genus of Ciliata (for Apiosoma jnscicola, ectoparasitic 

 upon the skin of fishes). From these data, Piroplasma would appear to be the correct 

 name ; but in 1893 Starcovici gave the name Babesia bovis to the blood-parasite of 

 cattle described by Babes (1888) under the name Haematococcus bovis, which according 

 to Laveran is identical generically and specifically with the Texas-fever parasite. If 

 that is the case, the correct name of the genus would be Babesia, and the species 

 parasitic on oxen should be called Babesia bovis (Babes). 



