31g C. ISHIKAWA. 



that the kinetic centre — the l'olkörijcrcfwn — of Englypha is derived 

 from the cytoplasm and not from the niicJear suhstance, just as in 

 the case of No(;ti 1 iica . Ihit -while in Noctiluca the archoplasm 

 appears to remain in the cytijplasm, in Englypha it l)ecomes inter- 

 mixed witli tlie nucleus, when the division of the latter is completed, 

 as we see from tlie following words of Sdienuakoff' (32, p. 2o(S) : — 

 " Vor alien Dingen wird das ehemnJigen Polkörperchen vollkommen in 

 die Ivernsuijstanz eingezogen; man gewahrt nichts mehr von den linsen- 

 artigen Hervorstiilpung ; wie es noch in den kurz vorhergehenden 

 Stadien der Fall war, sondern der Kern erscheint einheitlich und besitzt 

 eine regelmässige glatte Oberfläche." It tlius a])pears, that the Polkör- 

 perchen here are formed from the cytoplasm at the beginning of the 

 nuclear division, and become drawn into the Ixjdy of the nucleus at 

 the end of it. The Folkörpercheii is therefore not a permanent body, 

 but has always to be formed anew from a part of the cytoplasm at 

 the beginning of each nuclear division. As I have no ground to 

 doubt the accuracy of the very beautiful ol^servations of Sclwirialwf, 

 I have onlv to conclude that the fate of his PolkorpercJien is not 

 exactly the same with that of the archoplasm of Noctiluca, nor 

 do 1 doubt the observations of Herlie'uj and others of the kinetic 

 centres lyiug within the nucleus. From all this it apjiears that 

 the above statement of 11. Herlwiij as regards the position of the 

 kinetic substance in Protozoa, and Metazoa, holds true ; that in 

 I'rotozoa, this substance lies within the nucleus and that in Meta- 

 zoa it lies outside it. Jkit it apjjears also that there is considerable 

 fluctuation within the Protozoa. Of special interest in this con- 

 nection is the ])Osition of the archoplasm in Noctiluca and in 

 Le pt od is eus — the two relatives of Cy s to flagellât a : for while 

 in Leptodiscus this substance lies within the nucleus, in Nocti- 

 luca it lies outside it. Cystoflagellata thus forms, in this res- 



