22 



ANATOMY FOR NURSES 



[Chap. Ill 



Cytoplasm. — The cytoplasm is a viscid semi-fluid substance, 

 sometimes homogeneous, often granular, and has the appear- 

 ance of a meshwork. In this meshwork are often suspended 

 various passive bodies, such as food granules, pigment bodies, 

 drops of oil or water. These may represent reserve food matters, 

 or waste matters, and are collectively designated as metaplasm. 



Nucleus. — The structure of the nucleus is similar to that of 

 the cytoplasm, hut it is more solid, and differs in chemical com- 

 position. It is bounded by a membrane which separates it from 

 the surrounding cytoplasm, and may or may not contain the mi- 

 nute spherical bodies termed nucleoli. In some cells no nucleus 

 can be found. It may be assumed as true that at some period of 



AUnct'ion-lphtrc eticlo«ing two centtosOEDCS. 



r.i-s(ve bodKt (men. 

 pljsm or Dinplaim) 

 suspended in the cy- 

 lopMsmic meshvork 



Fig. 6. — Diagram of a cell. (Wilson.) 



its life every cell had a nucleus, though it may have been lost in the 

 course of development. 



Centrosome. — The centrosome is an extremely minute body 

 or pair of bodies usually surrounded by a mass of cytoplasm 

 known as the attraction sphere. As a rule it lies in the cytopla.sm, 

 not far from the nucleus, and plays an important part in nuclear 

 division. 



Life activities in cells. — Since the body is composed of cells, 

 it follows that all the activities of the body are the result of the 

 activities of the cells. These activities produce changes in the 

 protoplasm, the chief of which may be enumerated as follows : — 



(1) Respiration. — Each cell coming in contact with oxygen 

 absorbs it and combines with it. Whenever this combination takes 



