XI 



THE ELEMENTS OF STRUCTURE 



199 



the white blood corpuscles or leucocytes, are between 

 these extremes, and resemble the amoeboid Protozoa. 



But it is true of most of them that they consist (1) of a 

 complex, and in part living cell-substance, in which keen 

 eyes looking through good microscopes detect an intricate 

 network, or sometimes the appearance of a fine foam ; 



C 



N CHR 



M 



V 



FIG. 52. DRAWING OF A MODEL OF A CELL. 



N is the spherical nucleus, containing two coiled chromosomes (CHR), 

 one of which shows a thickening of chromatin. 



To the left are two centrosomes (C),with fine radiating filaments around 

 each and between them. 



The general cell-substance or cytoplasm (CY) shows a complicated re- 

 ticular structure. There are several vacuoles (V). 



What is called a chromidial apparatus (CH) consists of chromatin 

 granules which appear to have passed from the nucleus into the cytoplasm. 



There are also two groups of mitochondria (M), formed bodies in the 

 cytoplasm which are connected with particular functions of the cell. 



(2) of a central kernel or nucleus, which plays an essential 

 part in the life of the cell and contains a little world in 

 itself of ' chromosomes ' and other bodies ; (3) of a 

 slight outer membrane, varying much in defmiteness 



