22 



PROTOPLASM AND THE CELL 



part of the entire cell, but in this respect, also, the nucleus varies largely. 

 In some sorts of leukocytes, for example, the nucleus largely fills the 

 cell-wall. In one respect only is the nucleus constant namely, in its 



FIG. 3 

 Attraction sphere enclosing the centrosomes. 



Nucleus 



Plasmosome or 

 true nucleolus. 



Chromatin- 



network, 

 Linin-network . 



Karyosome or 

 net-knot. 



Plastids lying in 

 the cytoplasm. 



Vacuole. 



Lifeless bodies 

 (metaplasm) sus- 

 pended in the 

 cytoplasmic re- 

 ticulum. 



Diagram of a cell. (Wilson.) 



presence in some place and form and size in every living cell. To this 

 there is, for purposes of definition, no exception, for the erythrocytes 

 (see page 263) are not called cells, but corpuscles, because they seem at 

 present to have no nuclei. The nuclear sap is indistinguishable in its 



FIG. 4 



A bit of the nucleus of the infusorian Stylonichia. (Peytoureau.) 



nature from the similar liquid of the cytoplasm. The linin network is an 

 extremely delicate structure that does not stain with the ordinary dyes. 

 C. Schneider maintains that the filaments of linin are continuous through 



