266 H. M. WOODCOCK. 



or none at all (cf. above), the possibility of these organisms 

 possessing an undulating membrane during certain phases of 

 the life-history, when this is undergone in normal conditions, 

 is by no means excluded. On the contrary, indeed, the 

 markedly Herpetomonad-like facies of the parasites, which 

 greatly resembles that of '^ cultivated" Haemoflagellates, 

 strongly points to their being closely related to this group. 

 Tf so, there can be little doubt that Piroplasma (Leish- 

 mania) donovani (and, by inference, P. (L.) tropicum) 

 also has, at some period or other, a typical trypaniform phase. 

 Nothing is known with regard to the transmission of the 

 parasites, and the possible occurrence of an alternate host. 

 The superficial position of the localised form strongly points 

 to infection in this case by the bite of some blood-sucking 

 Insect.i That being so, it seems most natural to infer that 

 the same holds for the splenic type, although what determines 

 the limitation of the parasites in the one case, and their 

 dissemination throughout the system in the other, remains a 

 mystery. It has been suggested that, in the case of the 

 latter type, the organisms leave the host by way of the 

 alimentary canal, since they have been found in ulcers of 

 the large intestine. At any rate, it is very likely that an 

 important part of the life-cycle is passed through outside 

 the human host, thongh whether in the free condition or in 

 an Insectan host, or in both combined, has still to be learnt.- 



1 Crombie (' Brit. Med. Journ.,' 1904, ii, p. G58) points out that persons 

 who attend upon camels are very liable to a form of oriental sore. The 

 camel is the host of a Trypanosome and, possibly, the " camel-fly " transmits 

 the parasites to man. There is, indeed, a close parallelism between the 

 distribution of camels and oriental sore. 



^ Rogers' experiments showing that the parasites live and develop in 

 cold solutions outside the body, but rapidly degenerate when kept at blood 

 heat, point to the first part of tliis sentence being correct. With regard to 

 the second part, this same worker, in a more recent note (139), finds that 

 cultures of the parasites (Leishman's form) develop most rapidly and 

 successfully in an acid medium. In his opinion, this indicates the acid- 

 containing contents of the stomach of some blood-sucking Insect as the 

 place in which the e.xtra-corporeal stages of the parasite's existence are 



