342 MONTGOMERY. [Vol. XV. 



" Binnenkorper " are not organs, since they show no fixed 

 organic structure, but represent accumulations of various sub- 

 stances. There is more nucleolar substance, " Reservestoff," 

 accumulated in the nucleus before mitosis than is necessary 

 for it, so that after a mitosis some always remains to serve for 

 the production of daughter-nucleoli (this being an explanation 

 for the reappearance of nucleoli after mitosis). 



Stauffacher ('93), maturation of the egg of Cyclas: the 

 " Urei " contains a single large nucleolus ; later one or two 

 " Nebennucleoli " also appear in the nucleus. When the ovum 

 has so increased in size that it adheres to the wall of the ovary 

 only by a narrow thread of cytoplasm, two nucleoli are present, 

 which are of unequal size but are in close contact with each 

 other ; in one case the nucleolus was trilobular. After borax- 

 carmine staining, the smaller one appeared more refractive and 

 deeply stained than the larger. Subsequently the two became 

 separated, and both vanished before the formation of the first 

 pole spindle. 



Strasburger's paper ('93) presents a general discussion of 

 certain problems of mitosis in animals and plants ; his 

 remarks on the aequatorial plate are apropos here. He believes 

 that the " Kornchen " found by Kostanecki ('92) in the equator 

 of the central spindle are similar to, and comparable with, 

 structures found by himself in the mitoses of plants, and are 

 masses of nucleolar substance (these bodies being termed 

 " Centralspindelkorperchen " by Kostanecki, " Zwischenkor- 

 per " by Flemming, and " Zwischenkiigelchen " by O. Hertwig, 

 '92). " Vergegenwartige ich mir nun das, was ich seinerzeit bei 

 der Bildung pflanzlicher Zellplatten beobachtet habe [Histol. 

 Beitr., vol. i, p. i6i], namlich das Fortschreiten jener tingir- 

 baren Substanz, die ihrem Auftreten und ihren Tinctionen 

 nach nur als Nucleolarsubstanz gelten konnte, zwischen den 

 Verbindungsfaden bis zum Aequator, so muss in mir die Vor- 

 stellung erwachen, dass es sich in der von v. Kostanecki 

 geschilderten Erscheinung um einen entsprechenden Vorgang 

 handle. . . . Mit den durchschnittenen [achromatischen] Ver- 

 bindungsfaden . . . wanderte dann auch die Substanz der 

 halbirten Zwischenkorper nach den Zellkernen zuriick, ahnlich, 



