CELLS 



29 



The nucleus, which is set off from the cytoplasm by a nuclear mem- 

 brane, shows a fine network of fibers known as linin fibers; and scattered 

 throughout the nucleus, adhering to these hnin fibers, are masses of 

 another substance known as chromafm. This name was given to this 

 substance because it takes dyes or stains to a very high degree and when 



Fig. 4. — Various types of cells. A, epithelial cell shed from the lining of the human 

 mouth; a is a side view of the cell. X 300. /J, human ovum, nearly mature. X 200. C, 

 human sperm cell. X 1-300. D, diagram of a nerve cell. E, a bone cell; somewhat dia- 

 grammatic. X 700. F, human blood corpuscles. X 1,000. G, nonstriated muscle cell 

 from mammalian intestine. X 640. 



the cell is subjected to these, the chromatin stands out as scattered, 

 deeply stained particles. A body which shows plainly in the nucleus is 

 known as a nucleolus. Nucleoli, however, are of various kinds. Some 

 are called plasmosomes or true nucleoh. Sometimes such a body is made 

 up of granules of the chromatin massed together and is called a karyosome 



