THE CELL DOCTRINE. 119 



of various cells, araoebse, blood-corpuscles, cartilage- 

 cells, bone-cells, epithelial cells, etc., contain net- 

 works of minute fibrils, into which pass fibrils radi- 

 ating from the interior of the nuclei of these cells. 



In 1875, Frommann* again described, in accordance 

 with Heitzmann, a minute network of fibrils in the 

 nuclei of blood-corpuscles of Astacus fluviatilis, which 

 passed through the nuclear membrane into a similar 

 network in the substance of the blood-corpuscles. 



Schwalbe,t in 1875, found the nucleoli in the nuclei 

 of ganglion-cells in the retina often possessed of mi- 

 nute filamentous prolongations, and the nuclear 

 membrane showing prominences on its inner surface, j 

 Schwalbe designates as " nucleolarsubstanz," the nu- 

 cleolus and filaments, nuclear membrane and its 

 prominences, to distinguish it from the rest of nu- 

 clear matter, which he calls " kernsaft " or " nuclear 

 juice." 



KupfferjJ in 1875, maintained that the substance 

 of the lower cells of the frog, the odontoblasts, the 

 epithelial cells of the salivary gland of Periplaneta 

 orientalis, is composed of a hyaline (non-fluid) ground 



See also a paper by Heitzmann on the same subject, in the New 

 Tork Medical Journal for 1877. For the historical facts from this 

 date in the development of these new views, 1 am indebted to the 

 very valuable paper of Dr. Klein in the Quarterly Journal of Mi- 

 croscopical Science for July, 1878. 



* Frommann, Zur Lehre von der Struotur der Zellen, Jenaische 

 Zeitschrift f. Naturw., Bd. ix, 1875, p. 280. 



f Bemerkungen iiber d. Kerne d. Ganglionzellen, Jenaische 

 Zeitschrift f. Naturw., Bd. x, 1875, p. 25. 



J UeherDifferenzirung d. Protoplasmaan den Zellen thierescher 

 Gew., Schriften ,des Naturw. Vereins f. Schleswig-Holstein, Heft 

 ill; and Beitr. z. Anat. u. Physiol., Pcstgabe f. Carl Ludwig, 1875. 



