534 MONTGOMERY. [Vol. XV. 



zwischen Kern und Zelle " ; he opposes the view "dass die 

 Kernkorper aus dem Zellplasma in den Kern hineingelangen 

 und hier in die Bildung des Chromatins eingehen." Leydig 

 ("85) holds that certain of the nucleoli are differentiations of 

 the chromatin reticulum, others of the " Kernplasma." Watase 

 ('94) considers that they may be metabolic products of the cell. 

 Auerbach ('90) holds them to be the fundamental constituents 

 of the nucleus, which is a retrogression to the earlier views of 

 O. and R. Hertwig. Born ('94) states : " Die Nucleolen stehen 

 in Beziehung zum individuellen Zellleben, nicht zur Fortpflan- 

 zung." Lavdowsky ('94) considers them to be reserve masses 

 of chromatin. Macfarlane ('81, '85) regards them as the tropic 

 centers of the cell, and as the most important mechanical agents 

 in cell division. Julin ('96b) believes they conduct the vegetal 

 processes of the cell. Mottier ('97) considers the nucleolus 

 " ein Kraftvorrath, welcher der Zelle nach Bedarf zur Verfii- 

 gung steht " ; and Swingle ('97), as a reserve fund of nourish- 

 ment for the kinoplasm in mitosis. Metzner ('94) considers 

 them to be of importance in the processes of mitosis (compare 

 his observations). Henneguy ('93) regards the nucleolus and 

 Balbianian corpuscles as corresponding with the macronucleus 

 of the Infusoria {cf. Julin, '93b). These, then, are the most 

 important views on the nature of the nucleolus.^ 



From my own observations the nucleolar substance would 

 seem to be e.xtranuclear in origin, and not a secretion or excre- 

 tion of the nucleus. To be sure it may, and probably does, 

 undergo chemical changes within the nucleus, but it is derived 

 in the first place from the cytoplasm. I regard the nucleoli as 



' The following list includes, I believe, all who have written on the function of 

 the nucleolus : Korschelt ('89), Hacker ('93a, '95, '97b), O. Ilertwig ('77a, '92), 

 Rhumbler ('93), R. Hertwig ('76, '96), Kick ('93), Lukjanow ('88), Brauer ('91), 

 Xussbaum ('82), Strasburger ('82b, '84, '88, '95, '97), Jordan ('93), Flemming 

 ('80, '82), Van Beneden ('75), Wasielevsky ('93), A. Schneider ('83), Henneguy 

 ('93), Riickert ('92, '94), C. Schneider ('91), Born ('94), R. Wagner ('36, '37), 

 Auerbach ('74a), Kolliker ('43), I.onnberg ('92), Klein ('78), Macallum ('91, 

 '95), Stuhlmann ('86), O. Brandt ('78), Schwarz ('87), Giugnard ('85), Macfar- 

 lane ('81, '85, '92), Zacharias ('85), Watase ('94), Humphrey ('94), Gjurasin 

 ('93), Mann ('92), Julin ('93b), E. B. Wilson ('96), Van Bambeke ('85), Mottier 

 ('97), Swingle ('97), Rosen ('95), Metzner ('94), Wheeler ('97), Carnoy ('84, 

 '86, '97a, '97b). 



