270 WATASE. [Vol. IV. 



the spindle with the corresponding retraction of the chromatic 

 filaments toward the equator of the nucleus, show the same 

 thing, and that the spindle material does not originate inside 

 of the nucleus, properly speaking, but comes from the outside } 



The most convincing facts in regard to the truth of the polar 

 invasion of the archoplasmic filaments, in the nucleus with the 

 firm nuclear membrane around it, are afforded by Butschli's ^ 

 observation in the living Qgg of BrancJiipiis, by Mark ^ in 

 Limax, by Platner^ in Aulostoma, and by Garnault* in Helix. 

 Further, I believe that the facts given by these naturalists have 

 the same significance in the course of caryokinetic phenomena, 

 which I have ascribed to them in the preceding pages, in the 

 case of Cephalopods. 



To van Beneden's works references have already been made 

 in the preceding pages. The following is the summary of his 

 more recent results in his studies on the mechanics of caryo- 

 kinesis in Ascaris megalocepJiala, which he carried out in con- 

 junction with A. Neyt : — ^ 



"Dans notre opinion," van Beneden and Neyt observe, "tous 

 les mouvements internes qui accompagnent la division cellulaire 

 ont leur cause immediate dans la contractilite des fibrilles du 

 protoplasme cellulaire [archoplasmic fibrils] et dans leur arrange- 

 ment en une sorte de systeme musculaire radiaire, [archoplasmic 

 sphere] compose de groupes antagonistes ; le corpuscule central 

 joue dans le systeme le role d'un organe d'insertion. Des divers 

 organes de la cellule c'est lui qui se divise en premier lieu, et 

 son dedoublements amene le groupement des elements con- 

 tractus de la cellule en deux systemes ayant chacun leur centre. 

 La presence de ces deux systemes entraine la division cellulaire 

 et determine activement le cheminement des etoiles chromatiques 

 secondaires dans des directions opposees. Une partie impor- 

 tante des phenomenes qui constituent la cinese a done sa cause 

 efficiente, non dans Ic noyau, mats dans le corps protoplasmiqiie 

 de la cellule. 



^ O. Biitschli : Siudien ilber die ersten Entwicklungsvorg'dnge der Eizelle, die 

 Zelltheilung und die Conjugation der Infiisorien. 1875. Taf. XIII, Fig. 14. 



2 Mark: Mattiration, Fe7-tilization, Segmentation of Limax 



3 Platner : Arch. f. Mik. Anat., Bd. 33. 



* Garnault : Bull. Scientifique de la France et de la Belgique, Tome XXII. 

 ^ E. van Beneden and A. Neyt: Nouvelle recherches, etc., p. 280. (Italics are my 

 own.) 



