370 L-r. H. E. Ziegler on Amitotic Nuchar Division 



if amitotic division of the nucleus sets in, it is not usually 

 followed by division of the cell. 



In Triton (according to Klein *) the figures of amitotic 

 nuclear division are met with in the large gland-cells which 

 clotlie (or, more correctly speaking, till) tlse sac-shaj)ed 

 dernial glands, and multinuclear cells are also found among 

 them. 



In Anilocra (an Isopod Crustacean) O. voni Rath f found 

 veiy huge nuclei, which divide witliout mitosis, in large 

 glandular cells, which in all probability 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 e|)ithelinm ol the alimentary caiuil of 

 Crustacea and Insects |, in the hepatic tubules of Crustacea, 

 and in the Malpighian tubes of Insects. For we have here 

 alv\ays to deal with cells of a glandular character. 



"W'ith regard to the Malpighian tubes, amitotic division 

 was found in the larva of ApropJwra spumciria by Carnoy § 

 and in Dytiscus marginalis by Platner |i. " 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 tind no mitosis. We meet with the greatest difference in 

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



fact that tlie nuclei are of quite extraordinary importance for such cells, 

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

 receive lurther support for this conjecture in the fact that the nuclei do 

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

 onlv acquire these when the cells enter upon their functions." 



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

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

 1879. 



t O. vom Eath, " Ueber eine eigenartige polyzentrische Anordnung 

 des Chromatins," /oologischer Anzeiger, 1890, p. 334. 



\ In Nematodes also amitotic nuclear division occurs in the epithelium 

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

 division and multinu( liar cells in the alimentary canal of sexually mature 

 individuals of jRhabdonema niyrovenosum (Hoyer, '* Ueber ein f'iir das 

 Studium der 'direkten' Kernteilung vorziiglicli geeignetes Objekt," 

 Anatom. Anzeiger, 5 Jahrg. 1890, p. 2(3). 



§ J. B, Carnoy, "La Cytodi^rese chez les Arthropodes," La Cellule, 

 t. i., 1884, p. 219. 



II G. Platner, "Beitrage zur Keuntnis der Zelle und ihre Teilungs- 

 •'rschpinungen," Archiv f. niikrosk. Anatomic, 33 Bd. 



