018 MURIEL ROBERTSON AND E. A. MINCHIN. 



nucleus is "a complete nucleus with centrosome and eiglit 

 chromosomes, not merely a centrosome, karyosome, nucleolus, 

 or a simple ectoplasmic thickening.'' (The contrast drawn 

 between a nucleus and a centrosome in this sentence is 

 instructive.) The kinetonucleus then divides by another 

 lieteropolar mitosis and gives rise to a third nucleus, the 

 smallest of the three ; this third nucleus forms a nuclear 

 spindle composed of eight mantle-fibres and a ''central 

 spindle " or centrodesmose connecting the two centrosomes 

 situated at the two poles of the spindle. The central spindle 

 becomes the flagellum and the eight mantle-fibres the eight 

 myouemes. By growth and elongation of the flagellum and 

 myonemes, one centrosome is carried out at the tip of the 

 flagellum, while the other remains as its basal granule. Frotn 

 these statements of Schaudinn, it may at least be said without 

 expressing any opinion as to the accuracy of the details in 

 the development described by him that he regarded the basal 

 granule of the flagellum as a centrosome, and that he dis- 

 tinguished clearly between a centrosome and a nucleus, and 

 in particular between the kinetonucleus and the centrosomic 

 body from which the flagellum arises, although he used, in 

 our opinion quite wrongly, the term "blepharoplast" to denote 

 the kinetonucleus, instead of apph'ingit to the basal granule 

 of the flagellum. This mistake, as Ave consider it, in 

 Schaudinn's terminolog}' is the more remarkable, since he 

 seems to have understood so clearly the true centrosomic 

 nature of the basal granule of the flagelluni, and to have 

 realised its existence independent of the kinetic nucleus. 



The most important contribution to the question of the 

 blepharoplast in the Protozoa is the memoir of Jahn (8) on 

 the swarm-spoi'es of one of the Mycetozoa, Stemonitis 

 flaccida. He finds that at division the centrosomes at the 

 poles of the nuclear spindle give rise to the daughter-flagella 

 while still actually engaged in their centrosomic functions ; 

 a state of things entirely parallel to that which we have found 

 in the collar-cells we have studied. 



Hamburger (5) found in D una Hell a the paii'ed flagella 



