THE CELL AND PROTOPLASM. 



Ill 



relative to the size of the cell; sometimes 

 especially in young cells the nucleus being 

 very large, while in other cases the nucleus is 

 very small and the protoplasmic contents of the 

 cell very large ; finally, in cells which have lost 

 their activity the nucleus may almost or entirely 

 disappear. They differ, secondly, in shape. The 

 typical form appears to be spherical or nearly 

 so ; but from this typical form they may vary, 



FIQ. 26. Different forms of nucleii. 



becoming irregular or elongated. They are some- 

 times drawn out into long masses looking like a. 

 string of beads (Fig. 24), or, again, resembling 

 minute coiled worms (Fig. 21), while in still 

 other cells they may be branching like the 

 twigs of a tree. The form and shape of the 

 chromatin thread differs widely. Sometimes 

 this appears to be mere reticulum (Fig. 23) ; at 

 others, a short thread which is somewhat twisted 



