]."jO Ml. .1. {•]. S. Mooic — Observations u/ion Amcioba. 



nucleus and attraction sphere, which may well retain llu' 

 name of" Nebenkern "*. 



In May h\st I succeeded in adducing evidence in .su|)i)<n-t of 

 the view, first initiated by I'Menmiinj^ I believe, that the 

 karyokinetic division of a cell is in reality an expression of 

 two metamorphoses, each to a certain extent indejiendent of 

 the other f : one affects the attraction-sphere and the dividing;; 

 central bodies, the other the nucleus and the dividing chromo- 

 somes. And it is probable that this apparent duality in the 

 raetamorj)hosis may have had much to do with the modern 

 conception that the protozoan micro-nucleus is more or less 

 equivalent to the metazoan central body, and the metazoan 

 chromatic element to the protozoan macro-nucleus \. 



1 am not of tiiis opinion, for I fail to see how a structure 

 ]iresenting all the features of a karyokinetic division, such as 

 is seen in the micro-nucleus of a Paramivcium or a Colpidium, 

 c; n be compared with the central body of a cell, metazoan or 

 other. 



That tiie great macro-nucleus, where it exists in the Infu- 

 soria, is intimately related in some way or other to the 

 digestive activity of the animal seems highly probable. 

 Indeed it is difficult to see what other functions could be 

 assigned to it ; and the Ciliate as a single cell will have to 

 peiform all those secretive operations which in more highly 

 s] ecialized organisms would be told off to particular glandular 

 organs §. 



Thus it becomes possible that the existence of the " Neben- 

 kirn " in many gland-cells of the Metazoa (if that structure 

 can be shown to be there normal) may offer an analogy to 

 that differentiation of the nuclear elements apparent in the 

 ciliate Infusoria. Whatever be the ultimate solution of 



' See " Contributions to Morphol. and Pliysiol of the Cell,'' Macalluin, 

 Trans. Canadian Institute, vol. i. pt. 2 ; Steiuhaus, " Ucber para.*itare 

 Ein.sclilus.se in deu Panciea.<zplKn dcr Anipliibien,'' Zit'jjler's lieitra;re 

 zur Path. Anat. und zur Allj,am. Path. Jid. vii. p. 3t>7 : Nu.s.shauui, 

 " Ueber den Iku ui;d die Thiiti-rkeit der DriLsen," Arcii. fiir luikr. Anat. 

 lid. xxi. p. 2U0. 



t Unpublished paper in the hand.s of the editor Quart. Jouru. Micr. 

 Sci. 



X Cf. II. E. Ziogler, ' Biologisches Centralblatt,' Bd. xi. uos. 12 and 1."., 

 pp. 372-38!) ; and IJutschli, " L'eljer die sogr. Centralkfirper der Zellc ui,d 

 ihre Bedeutunfr," Verhandl. d. Naturhi.st.-u]ed, Vereins zu IIe;delber<r, 

 Hd. iv. 



§ This view receives S(/nie support from a consideration of the multi- 

 nucleate parasite Opulina. ilore, where there is no need for di},'i'stive 

 activity, as the aniu;al is immersed in already digested food-malarial, v.<; 

 find a corresponding simjjlilication of the nuclear elements, uU of wliiclj 

 present tiie mirrn-nucl' ar karyokin-tically dividing .structure. 



