562 SUMMARY OF CURRENT RESEARCHES RELATING TO 



in Yorticellidfe in the form of grains of the secretions saphi'anophile and 

 siderophile. On the other hand, the mitochondrial apparatns of Infusoria 

 is not unconnected with the chromidial apparatus to be found in many 

 Protozoa. Sphaeroplasts constitute a sort of cytoplasmic chromidium 

 entu'ely independent of the nuclear, although its evolution is parallel to 

 it. There is a synchronism in the phenomena of bipartition. 



Encystation of Trypanosoma grayi.* — E. A. Minchin describes 

 stages of encystment of Trypanosoma grayi as observed in the procto- 

 deum of an infected tsetse fly. He regards these as similar to the 

 " Schleim-Cysten " described by Prowazek in Herpetomonas muscoi- 

 domesticce, and that they are destined to pass from the fly along with its 

 dejecta. Most probably in this case they contaminate the food or 

 drink of a vertebrate host, develop in its digestive tract and pass thence 

 into the blood, whence they are again taken up by the tsetse fly. 



New Trypanosomes.t — ^Marchoux and Salembeni describe Trypano- 

 soma BorrelU sp. n., from Hyla lateristriga. It is clearly distinct from 

 T. rotatorium ; it has no free flagellum, and differs in shape in the young 

 stages from that of the adult condition. 



Gustave Martin | records from a lizard, llabuia raddonii, in French 

 Guiana, Trypanosoma ho net i. It is very rare and resembles T. rota- 

 torium. The flagellum hardly projects beyond the body. 



Life-cycle of Trypanosoma gambiense.§ — J. E. Salviu-Moore and 

 Anton Breinl are of opinion that the so-called male and female trypano- 

 somes of Prowacek, Minchin and others are more likely to be arbitrarily 

 chosen extremes in a continuous series of dimensions. They find that, 

 in inoculated rats, as the number of parasites is increasing there is only 

 amitotic fission of micro- and macro-nuclei. At the maximum stage 

 from 5-20 per cent, of the trypanosomes show a thick stainable band 

 growing out from the micro-nucleus and extending towards the macro- 

 nucleus. This is quite distinct from, and thicker than, the stainable 

 margin of the undulating membrane. At this stage micro- and macro- 

 nucleus thus become connected. Later, when the number of parasites 

 in the blood is falling off, trypanosomes in the bone marrow, and spleen 

 disintegrate, the flagellum and remains of micro-nucleus becoming 

 detached. Around the nucleus there has previously formed a definitely 

 bounded hyaline area ; these together remain intact, undergo no further 

 change, and form " resistant " bodies. During the negative period of 

 infection, they appear to decrease in size, but at the time of the 

 reappearance of the trypanosome in the blood, they enlarge, the nucleus 

 buds off a small micro-nuclear granule, and from this, at a later stage, 

 there grows out a flagellum, and small trypanosomes result. Thus it 

 appears that Trypanosoma gamhiense has a life-cycle complete within 

 the body of one animal, as is the case with the parasite of dourine ; this 

 suggests that contagion may be effected by a mere mechanical trans- 

 mission of blood. 



* Proc. Roy. Soc, Series B, Ixxix. (1907) No. B 528, pp. 35-40. 



+ C.R. Soc. Biol. Pads, Ixii. (1907) pp. 592-4. 



X Tom. cit., pp. 594-6. § Lancet, 1907, pp. 1219-20. 



