716 H. M. WOODCOCK. 



impression of the gi'oup, and one which is further from the 

 truth than the views expressed in my article. 



(c) Notes on Nuclear Cytology and Division. 



My material, having been all stained by the Ronianowsky 

 method, has not proved very suitable for a study of the 

 minute structure of the nucleus (trophonucleus). Neverthe- 

 less, in the light of the interpretation which Minchin and 

 Woodcock (13) have shown is to be placed upon the 

 " Griemsa-picture " of the nucleus of a ti-ypanosome, I am 

 able to say that, in the case of many, at any rate, of the 

 parasites observed, the type of nuclear structure certainly 

 agrees with that described in that paper. Unfortunately, in 

 the parasites figured from the blood of the bird, the nucleus 

 often shows the usual granular appearance; now and then, 

 however, the definite clear region can be seen, corresponding 

 to the central, plastinoid part of the karyosome, which con- 

 tains a deeply staining granule in the middle — the intra- 

 nuclear centrosoine (figs. 80, 84, and 51). For some reason or 

 other cultural forms show this appearance, which is to be 

 regarded as the typical one, much more frequently, indeed 

 quite regularly (figs. 7, 8, 72, etc.). The trophonucleus of the 

 individual in fig. 8 is in an interesting condition; it is more 

 faintly stained than usual, the nuclear sap apparently con- 

 taining little or no chromatin (cf . the numerous chromatoid 

 granules scattered in the surrounding cytoplasm). Whether 

 the deeply-stained central body represents in this case a small 

 karyosome or a greatly enlarged central granule, it is 

 impossible to say. Other instances of an unusual appearance 

 of the trophonucleus are seen in the parasites of figs. 38 and 

 39; here there appear to be a certain number of separate 

 chromatic masses, of varying size. This condition perhaps 

 represents a fragmentation of the single large karyosome 

 usually present. 



The blepharoplast, or basal granule, at the proximal end 

 of the flagellum is sometimes visible in the parasites from the 



