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 are 

 pervaded by a com.mon structural basis, morphologically continuous 



A 



B 



C 



D 



P'g- 7- — Various cells showing the typical parts. 



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

 Nucleus showing net-knots. [P'LEMMING.] 



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

 Nucleus with a smgle |ilasniosome. [Hermann.] 



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

 some with several centrioles. [Lenhossek.] 



D. Spermatocyte of Proleus. 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 are to 

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



^ The fact tliat the nucleus may move actively throui^h the cvtoplasm, as occurs iluring 

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

 continuity may at times be interrupted. 



