360 



TRYPANOSOMID^ 



has shown that this is merely a Herpetomonas or Leptomonas^ but 

 at the present time we retain it as a separate genus, as the full life- 

 cycle has never been completely traced. 



So far we have been considering genera in which there is no 

 doubt that one stage of the life-cycle is flagellate ; now we turn to 

 the other genera, concerning which doubt~is freely expressed as to 

 whether they belong to the Mastigophora at all. 



With regard to Toxoplasma, it was considered by some observers 

 to be allied to Leishmania, but it contains only a single nucleus, 

 without evidence of a kinetonucleus, and without the appearance of 

 a flagellate stage on cultivation; and its life-cycle is little known, 

 as. is that of an apparently allied genus, Elleipsisoma'Frsiii(;si, 1911, 

 while the relationship is further complicated by the genus Toddia 

 Franga, 191 1, which is said to arise from the infective granule. 

 There appears to be more flagellate evidence for the genus Glohidium 

 Neumann, 1909. The so-c3l\edLefwocytozodnpiroplasmoidesThiroux 

 and Teppaz appears to be allied to Toxoplasma, having only one 

 nucleus, and not developing any flagellate forms on cultivation. 

 Finally, the work of Yakimoff and Kohl-Yakimoff indicates that 

 Toxoplasma is related to the Haemogregarines, especially as Splen- 

 dore's flagellate stage has not been confirmed by Laveran's 

 work. 



The genus Piroplasma used to be classed with Herpetomonas 

 because flagellate forms had been found by several observers, but 

 these findings have been discredited because (i) they were discovered 

 in the old faulty air-dried smears; (2) the possibility of their being 

 intestinal flagellates of the genus Prowazekia, which entered the 

 blood before death in diseased animals; (3) they are really trypano- 

 somes, and not development stages of Piroplasma ; (4) the careful 

 work of Nuttall and his collaborators have failed to demonstrate 

 a flagellate stage. 



Achromaticus was placed with the Herpetomoninae because, 

 according to Gonder, it always has a trophonucleus and a kineto- 

 nucleus, while Neumann maintains that it becomes flagellate in 

 the bat mite, Pteropus vespertilionis. On the other hand, Yakimoff, 

 Stolnikoff, and Kohl-Yakimoff deny the presence of the double 

 nucleus, and consider the parasite to be a typical Piroplasma. 



According to Darling, Histoplasma becomes flagellated in the 

 lungs, and therefore belongs to the Herpetomoninae, though Rocha- 

 Lima considers it to be a yeast, a view which we adopt. 



Rhynchoidomonas belongs to the Trypant)sominae. 



We therefore recognize the following as definitely belonging to 

 the Herpetomoninae : — 



1. Herpetomonas Kent, 18S1. 



2. Leptomonas Kent, 1881. 



3. Crithidia Leger, 1902, emendavit Patton, 1908, 



4. Leishmania Ross, 1903. 



5. Hcemocystozoon Franchini, 1913. 



