THE H^MOPLAGELLATES. 263 



first considered tlie organisms as representing involution or degeneration 

 appearances of Trypanosomes, being largely influenced by tbe two unequal 

 chromatin masses ; in this view he has been supported by Marchand and 

 Ledinghara. Later, Leishman has gone somewhat farther, and regards 

 the parasites as perhaps representing an actual stage in the life-cycle of 

 a Trypanosome. Laveran and Mesnil, taking more particularly into account 

 the general form and very suggestive binary fission, considered the parasite 

 to be a new species of Piroplasma, which they called P. donovani; 

 donovani is, therefore, the correct specific name of this form. Donovan 

 concurred in this view, and Mesnil, Mouton and Remlinger (1. c), who have 

 studied Wright's form in a case of " bouton d'Alep " also consider this as 

 a Piroplasma, — probably, however, a distinct species.' 



Other authorities (e.g. Christophers, Ross and Wright) have gone some- 

 what wide of the mark, and have seen in this parasite an entirely different 

 kind of Sporozoan ; or, rather, they (with the exception of Wright) have 

 regarded the parasitic bodies as being, themselves, only the spores of a new 

 Myxosporidian, the parent body or plasma of which has not yet been satis- 

 factorily made out." This view is at once put out of court by the fact 

 that Sporozoan spores never divide up in the way these bodies admittedly 

 do; a valve or lid may open, liberating enclosed germs, after which the 

 spore-case is cast empty aside, but the whole spore, membrane and all, can- 

 not possibly divide up into two or more " daughter-spores ! " 



The above description of the parasites sufficiently justifies, 

 we think, Laveran and Mesnil's opinion that they agree 

 closely enough with the known stages of Piroplasma to 

 be considered as belonging to that type of organism.^ This 

 does not, of course, prejudice, in any way, the view that 

 these parasites represent, nevertheless, only a phase or part 

 of a complete life-cycle. Now, as mentioned above, there 

 is evidence that P. bigeminum is closely associated with 



1 The specific name, in that case, will be tropicum, as Wright termed 

 his form Helcosoma tropicum. 



' Ross, who has created the genus Leishmania for the parasites, thinks 

 the matrices above discussed represent " relics of the parent organism." 



* Since Schaudinn has observed nuclear dimorphism in a typical Piro- 

 plasma (namely, P. canis, see above, p. 254), any objection based upon 

 this feature of P. donovani is removed. The only difference of any 

 importance, in fact, appears to be that of habitat, and, granting this (though 

 the new parasites do not appear to be, by any means, exclusively leucocytic), 

 at least one Hieraosporidian, namely " Hse mam oeb a " (Trypanosoma) 

 ziemanni, also has a leucocytic habitat. 



