.•)7() llr. II. E. Zicgler on Arnitoti'c Xuchar J)t'ci'si(in 



if amitotic divif^ion of the nucleus sets in, it is not usually 

 followed by division of the cell. 



In Triton (according- to Klein *) the fi<i,-ures of amitotic 

 nuclear division are met with in the large glanil-cells whicli 

 clothe (or, more correctly s|H'aking, till) the sac-shai)ed 

 dermal glands, and multinuclear cells are also found among 

 them. 



In Ainlocra (an Isopod Crustacean) O. vom Rath f found 

 very large nuclei, which divide without mitosis, in large 

 glandular cells, which in all ])iol)aLility are the salivary 

 glands of the animal ; several nuclei are often found in one 

 cell. 



We now come to the cases of direct nuclear division which 

 are met with in the epithelium of the alimentary canal of 

 Crustacea and Insects \^ in the hepatic tubules of Crustacea, 

 and in the ]\lalpighian tubes of Insects. For we have here 

 alv\ ays to deal with cells of a gh\ndular character. 



With regard to the Malpighian tubes, amitotic division 

 was found in the larva of ApropJiora syumaria by Carnoy § 

 and in Dytiscvs margiimlis h\ Platner \\. " The cells of the 

 Malpighian vessels of Insects," writes Platner, " are exceeded 

 in size only by the ova. The diameter of the nucleus is often 

 three times larger, and even more, than that of the cells of 

 the Salamander, and at the same time, in spite of the most 

 vigorous multiplication of cells, necessitated by the consump- 

 tion which takes place when the organs are doing their work, 

 we find no mitosis. We meet with the greatest difference in 

 the size of the cells j the large cells contain one large nucleus, 



fact that the nuclei are of quite extraordinary importance for i?uch cells, 

 that they exercise a certain influence on the activity of tlie cell. We 

 receive turther support for this conjecture in the i'lict that the nuclei do 

 not at first possess the considerable circunifermce and unusual form, but 

 only acquire these -when the cells enter upon tluir functions." 



* E. Klein, "Observations ou the Glandular Epithelium and Division 

 of Nuclei in the Sliin of the Newt," Quart. Journ. Micr. Sci. vol. xix. 

 1879. 



t (). vom IJath, " Ueber eine eijrenartifre polyzentrische Anorduung 

 des Chromatins," Zoologischer Anzeiger, 1M>0, p. 334. 



\ In Nematodes also amitotic nuclear division occurs in the epithelium 

 of the alimentary canal. Iloyer found the figures of direct nuclear 

 division and multinuclear cells in the alimentary canal of sexually mature 

 individuals of lih(ihdo7n'ina nitirnnnnt^uin (^I lover, "Ueber ein fur das 

 Studium der ' direliten ' Kt riiteilung vorziiglich geeiguetes Objekt," 

 Anatoin. Anzeiger, 5 Jahrg. IH'.IO, p. '2<\). 



§ J. B. Carnoy, "La Cvtodi(5rese chez les Arthropodes," La Cellule, 

 t. i., 1884, p. 219. 



II G. Platner, "Beitrjige zur Kenntnis der Zelle uud ihre Teilungs- 

 erscht'inungen," .Vrchiv f mikrosl<. Anatomie, 33 Bd. 



