Young, Cytology of Cestoda. ^g^ 



S c h a x e 1 : Das Verhalten des Chromatins bei der Eibüdung einiger Hydro- 

 zoen. (Zool. Jahrb., Abt. Anat. Ontog., Bd. 31, S. 613 — 656, Taf. 31 bis 



33, I9H-) 

 Schaxel: Plasmastrukturen, Chondriosomen und Chromidien. (Anat. Anz., 

 Bd. 39, S. 337—553, J 6 Fig., 1911.) 



An diesen Vortrag schließt sich eine Besprechung, an welcher 

 sich die Herren: Dr. M. Nowikoff (Moskau), Prof. Dr. P. 

 Enriques (Bologna), Prof. Dr. A. Borgert (Bonn) und 

 der Vortragende beteiligen. 



Herr Prof. Dr. P. Enriques (Bologna) : ,,Richiamo Fatten- 

 zione dei colleghi sul fatto assai curioso, che, nonostante il passaggio 

 di sostanze dal nucleo nel citoplasma, non si vede mai nelle figure 

 del Dr. Schaxel, ed in generale, una rottura della membrane 

 nucleare, ciö che sembra indicare che la membrana stessa sia 

 in generale un prodotto artificiale dei reattivi, come del resto anche 

 fa credere il fatto che i nuclei per lo piu non si vedono nella cellula, 

 vivente e normale. 



Herr Dr. J. Schaxel: ,, Ich glaube in den Bemerkungen 

 der Herren keine wesentlichen Einwände erblicken zu müssen. 

 Der Nukleolus scheint mir überhaupt am besten bloß als topo- 

 graphischer Begriff aufgefaßt zu werden. Die Existenz einer 

 Kernmembran kann wohl nur an der Hand vitalen Materials dis- 

 kutiert werden. Im fixierten Präparat erscheint der Kern jeden- 

 falls deutlich umschrieben." 



Es wird nun der im Programm für die VIII. Sektion ange- 

 zeigte Vortrag des Herrn Prof. R. T. Young (North Dakota) 

 eingeschoben : 



Cytology of Cestoda. 



By Robert T. Young (North Dakota). 



In recent years considerable attention has been paid to ami- 

 tosis, and the former view that it was a process occurring only 

 in specialized cells, which were ultimately destined to degener ate 

 without undergoing further mitoses, has been largely abandoned. 



The genetic continuity of cells however is at present univer- 

 sally accepted, and the few exceptions which have been hitherto 

 claimed have not as yet been recognized. It is highly improbable 

 however that the most primitive organisms arose as finished cells 

 with well differentiated cell organs. That in most present organisms 

 the chromatin hhas become specialized as the pysical basis of 



r 



