312 



H. M. WOODCOCK. 



accounts are tliose of Laveran and Mesnil (145 a) and Perrin (146). According 

 to botl), the nucleus consists of numerous small chromatic masses, having the 

 form of grains or rodlets (c) transversely arran£^ed,and extending almost from 

 one end of the body to the other. These rodlets are about equidistant from 

 one another and separated by faintly-staining spaces. Further, according to 

 Perrin, these transverse bands are arranged in a single rove upon a delicate, 

 spirally-VFound thread or axis, the spiral being very flat where the chromatin 

 rodlets are. 



Tiie two accounts differ, however, concerning the other characteristic 

 feature of this parasite. Laveran and Mesnil consider that what appears to 



Fig. G3. — Spirochreta (Trypanosoma) balbianii (Certes). 

 (b, a number of individuals associated with the crystalline style of 

 a cockle.) A and b after Certes, c after Perrin. 



be an undulatiug membrane is, in reality, a wide, '*' periplastic " sheath or 

 investment, which may be attached only at the two ends, the greater part of 

 the body of the organism being more or less free inside it. In certain cir- 

 cumstances, es])ecially if flattened or ribbon-like, and having regard to the 

 sjjiral form of tiie body, this sheath would simulate the appearance of an 

 undulating membrane. Perrin, on the other hand, regards this structure as 

 a true undulating membrane, comparable to that of a Trypanosome, and 

 believes, in addition, that it possesses a thickened chromatic border, connected 

 to one end of the nuclear spiral by a delicate thread. 



It seems most likely that multiplication is by longitudinal, rather than by 

 transverse fission. Perrin describes the process as commencing by the 

 division of the undulating membrane ; this is followed by the transformation 



