178 SUMMARY OF CURRENT RESEARCHES RELATING TO 



tsetse fly, but is only transferred mechanically by the fly's proboscis. 

 There is, however, within the fly during the first twenty-four hours a 

 development of two distinct types, the one slender, transparent, and 

 active, the other bulky, granular, and sluggish in movement. Up to 

 forty-eight hours the multiplication continues, and a more " indifferent " 

 type of individual appears. At seventy-two hours, however, the try- 

 panosomes have become greatly diminished, and by ninety-six hours, or 

 slightly later, they have disappeared completely from the gut of the fly, 

 this disappearance coinciding with the complete absorption of the blood 

 with which they were taken in. These facts suggest the commencement 

 of a life-cycle which is not completed, but which might l^e so under 

 other conditions. It must be borne in mind that the sleeping sickness 

 is a new thing, apparently, on the Victoria Nyanza, as it has broken out 

 there comparatively recently in epidemic form. 



Morphology and Life-history of Piroplasma canis.* — G. H. F. 

 Nuttali and G. S. Graham-Smith describe the results of further investi- 

 gations on this parasite, having given particular attention to the study 

 of the hving organism. Nearly all forms of Piroplasma possess one 

 densely staining nucleus : many show a second punctiform blepharoplast 

 near it ; and a considerable number have a third loose mass of chromatin. 

 These masses may occupy various positions or assume various shapes. 

 Many intracorpuscnlar forms in stained preparations show both pseudo- 

 podia and flagella-like ])rocesses, and many of the free forms possess 

 distinct flagella. Round, apparently degenerating forms are common in 

 liver and spleen. Many of the appearances seen in stained preparations 

 are extremely deceptive, and deductions made from them are frequently 

 not confirmed by the study of the living forms ; various bodies occur in 

 normal dog's blood which are readily mistaken for piroplasmata. Piro- 

 plasma canis has a truly intra-corpuscular and an extra-corpuscular stage ; 

 the latter is frequently flagellate. Within the peripheral blood a definite 

 cycle of development occurs. Free piriform bodies invade the corpuscles, 

 becoming round and later amoeboid. The amoeboid ])odies, according to 

 their size, either again fonn intra-corpuscular pyriform bodies or divide 

 and form two or more pyriform bodies. These leave the corpuscles, and, 

 in doing so, rupture them and enter others. The author's observations 

 lend no support to any of the theories of development which have 

 hitherto been put forward. 



Development of Piroplasma canis.f — S. R. Christophers has been 

 successful in tracing the life-cycle of this parasite in India within the 

 tick, Rhipicepkalus sanguineus Latreille. In the gut of adults or 

 nymphs fed on infected dogs there are globular parasites which, con- 

 jugating, yield a club-shaped ookinete. In the case of the adult this 

 migrates to the ova. The larvae hatched from these are apparently 

 unable to transmit the parasite, but the nymph and adult may both do 

 so. Infection taken in during the nymphal engorgement can be trans- 

 mitted later by the adult stage. In the nymphs (unfed) bred from 

 infected mothers, there occur in the salivary cells swarms of small, 



* Journ. Hygiene, vi. (1906) pp. 586-650 (3 pis.), 

 t Brit. Med. Journ., Jan. 1907, pp. 76-8 CI fig.). 



