THE HJ}MOFLAGELLATES. 217 



the entire width of the body at that point (fig. 17, J and k). 

 There is sometimes a clear zone or halo surrounding this 

 organella, as in figs. 17 a, b, 23 c. Possibly this clear region 

 represents the cytoplasmic vacuole of other forms, which 

 usually lies close to the kinetonucleus (cf. figs. 52, 53). 

 In T. equinum the kinetonucleus is extremely small and 

 difficult to make out; according to Lignieres (71) and 

 Laveran and Mesnil it is a dot-like thickening at the root- 

 termination of the flagellum (fig. 16 d)^; in this form it has 

 apparently become secondarily reduced. 



In intimate relation with the kinetonucleus is the flagellum. 

 That portion lying in the general cytoplasm of the body is 

 distinguished as the rhizoplast. When the kinetonucleus 

 is situated near the non-flagellute end and, consequently, 

 nowhere far from the surface, the rhizoplast is very short, 

 and the flagellum leaves the cytoplasm almost at once, 

 becoming, of course, the flagellar border of the undulating 

 membrane. When the kinetonucleus is deeply situated, the 

 rhizoplast is somewhat longer, and (in Trypanosoma) 

 usually runs in an oblique direction to the point where it 

 emerges (figs. 17 a, 58). In Try panoplasma, the rhizo- 

 plastic portion of each flagellum is well-developed ; the two 

 are quite distinct, and lie parallel to each other (fig. 18). 



Apart from Schaudinn's observations, only in very few cases 

 up till now has the occurrence been recorded of a distinct 

 centrosomic granule, from which the flagellum originates. 

 Leger describes a well-marked granule {" diplosome ") at the 

 base of each rhizoplast in Trypanoplasma(fig. 18 b, c) j and 

 Keysselitz suspects the presence of similar ones in Trypano- 



' It is most easily demonstrated by using Laveran's special stain. In 

 this connection, and a propos of the genuineness of the vacuole mentioned 

 above, it is interesting to note that Elmassina and Migone (22) describe 

 (in preparations made according to their own method) a clear, refringent 

 sphere, situated very near the point where the flagellum emerges from the 

 body. This structure is not rendered visible, these authors find, by Laveran's 

 stain, although this alone reveals the kinetonucleus. From Elmassina and 

 Migone's description and figures it seems most likely that this refringent 

 sphere is a cytoplasmic vacuole. 



