OBSERVATIONS ON STRUCTURE OF CELLS AND NUCLEI. 315 



152. Semper. — Ueber die Eiitsteliung der geschichteten Cellulose-Epi- 

 dermis der Ascidien, Semper's ' Arbeiten,' B. ii, p. i. 1S75. 



153. Id. — Die Verwandtsehaftsbeziehungeu der gegliederteu Thiere, 

 Ibid,Y,.m. 1876. 



151;. Stmsburger. — Ueber Zellbilduiig und Zelltheilung. Jena, 1876. 



155. Id. — Ueber Bel'ruchtung und Zelltheilun?, ' Jenaische Zeitschr.,' 

 B. xi, p. 435. 1877. 



156. Villot. — L'liistologie de I'oeuf, ' La Revue des Sci. Nat.,' Tome v, 

 Dec., 1876. 



157- Weismann. — Die Entwicklung der Dipteren im Eie, uach Beobach- 

 tungen an Cliironomus, ' Zeitschr. f. wiss. Zoo!.,' B. xiii. 1863. 



158. ZeUer. — Untersuchungen fiber die Fortpflanzung der Opalinen, 

 'Zeitschr. f. wiss. Zool.,' B. xxix, p. 352. 1877. 



159. Id. — Weiterer Beitrag zur KenntnissderPolystomen, /i/</, B. xxvii, 

 p. 238. 1876. 



160. Disse.—'Diti Entwicklung des mittleren Keimblattes im Hiilmerei, 

 'Arch. f. Mik. Anat.,' B. xv. p. 67. _ 1878. 



161. Fcai Beneden. — A Contribution ta the History of the Embryonic 

 Development of the Teleosteans, ' Quart. Journ. Mic. Sci.,' vol. xviii, N. 

 S., Jan., 1878. 



162. i2«/cfZ and Warchoasky. — Zur Entwicklungsgeschiclite des Regeu- 

 wurms, ' Zeitschr. f. wiss. Zool.,' B. xviii, p. 547. 1868. 



Observations on the Structure of Cells and Nuclei. 

 By E. Klein, M.D., F.K.S. (With Plate XVI.) 



The knowledge of the structure of cells and cell-nuclei 

 has of late years been greatly extended by the observations 

 of Kleinenberg, Eimer, Heitzmann, Auerbach, Strassburger, 

 Frommann, Schwalbe, Biitschli, O, Hertwig, R. Hertwig, 

 KupfFer, van Beneden, W. Flemming, Eberth and others. It 

 is shown by the work of these observers that the substance 

 of cells, as well as that of their nuclei, is of a far more 

 complex nature than is indicated by the term ' granular' or 

 ' hyaline' — usually applied to it. 



Heitzmann^ asserts that the substance of various cells — 

 amoebae, blood-corpuscles, cartilage cells, bone cells, epithe- 

 lial cells, &c. — contain networks of minute fibrils, into which 

 pass fibrils radiating from the interior of the nuclei of those 

 cells. Kleinenberg, W. Flemming, O. Hertwig, and E. van 

 Beneden,^ observed a network of fibrils in the nucleus of the 

 ovum of various invertebrate and vertebrate animals. 



1 " Untersuchungen iiber das Protoplasma," ' Sitzungsber. d. k. Akad. d. 

 "Wiss. Vienna,' Bd. Ixvii and Isviii, Abth. iii, 1873. 



- Tor the detailed references see ^V. Elemming's paper in 'Arcliiv f. 

 Mikrosk. Anatom.,' Bd. xiii, p. 715. 



