i6 



GENERAL SKETCH OF THE CELL 



At a first examination the nucleus appears to be a perfectly dis- 

 tinct body suspended in the cytoplasm. Most of the latest researches 

 point, however, to the conclusion that nucleus and cytoplasm arc 

 pervaded by a common structural basis, morphologically continuous 



ig- 7- Various cells showing the typical parts. 



A. From peritoneal epithelium of the salamander-larva. Two centrosomes at the right. 

 Nucleus showing net-knots. [FLEMMING.] 



B. Spermatogonium of frog. Attraction-sphere (aster) containing a single centrosome. 

 Nucleus with a single plasmosome. [HERMANN.] 



C. Spinal ganglion-cell of frog. Attraction-sphere near the centre, containing a single centro- 

 some with several centrioles. [Ll.MlossEK.] 



D. Spermatocyte of 1'rolcus. Nucleus in the spireme-stage. Centrosome single ; attraction- 

 sphere containing rod-shaped bodies. [HERMANN.] 



under certain conditions from one to the other, and that both arc to 

 be regarded as specially differentiated areas in that basis. 1 The terms 



1 The fact that the nucleus may move actively through the cytoplasm, as occurs during 

 the fertilization of the egg and in some other cases, seems to show that the morphological 

 continuity may at times he interrupted. 



