Notes on (•erktin Blood- rnhahitiny Protozoa. 239 



of thickenings. I have on several occasions made out eight 

 of these, but the different masses of chromatin are only rarely 

 clearly defined in the karyosome. The whole nucleus is 

 bounded at this stage by that — for the Protozoa at least — 

 rather doubtful organ the nuclear membrane. Next to be de- 

 scribed is the centrosome, or as it may here, I think, be called, the 

 blepharoplast. This appears as a small but still well-defined 

 granule, and is to be seen in the vast majority, though not in 

 all, of the parasites — indeed, it is a very constant feature. 

 The position of the blepharoplast in relation to the nucleus 

 varies in an interesting and suggestive way. Thus, in what 

 I take to be one of the earlier stages, it is lying closely 

 apposed to the large nucleus (Text-Fig. 1). In a later stage the 

 blepharoplast is more remote, but is bound to the big nucleus by 

 aquitedefinitethread (Text-Fig. 2) : this thread seems ultimately 

 to disappear. The centrosome body is not an altogether simple 

 granule. When once it has left the near neighbourhood of 

 the large nucleus, it becomes clear that rays pass from it 

 into the cytoplasm. The centrosome or blepharoplast seems 

 capable of increasing slightly in size and of dividing, the 

 products showing a strong tendency to remain connected 

 together by a staining fibril. This process of division may 

 be repeated, and somewhat complex appearances are found ; 

 but owing to the limitations of the material, I am not in a 

 position to give a definite interpretation of the facts observed. 

 The blepharoplast is undoubtedly a product of the large 

 nucleus, but I cannot definitely say that it arises from it by 

 heteropolar mitosis. The evidence, however, is in favour of 

 this supposition, in which case the thread joining the blepharo- 

 plast to the large nucleus would correspond to the spindle 

 formed by the central granule, which, according to 

 Schaudinn's description, lies within the karyosome. So far 

 as I can see at present, the small nucleus or blepharoplast 

 does divide by mitosis, but the details are very obscure. 

 The phenomena just described strongly recall Schaudinn's 

 account of the development of the flagellar apparatus in 

 Trypanosoma noduce. This account is now too well known 

 to require recapitulation here. 



It is true that I have not yet found any actual flagellate 



