General Characters of Animals. 5 



There are three stages in the contest between waste 

 and repair which is characteristic of life. In the first, 

 repair is in excess of waste, and individual growth 

 proceeds until a definite limit, constant within certain 

 bounds for each specres, is reached. When this is 

 attained, excess of nutrition still continues but tends 

 to become separate and independent ; by such dis- 

 continuous modes of growth, the third set of functions, 

 or Reproduction, is accomplished. Of this there are 

 three chief forms : (A) either the whole body of the 

 parent may split into two or more, each becoming a 

 perfect animal like its parent ; this process is named 

 fission. (B) In the second mode of reproduction a small 

 portion of the body of the parent animal enlarges and 

 becomes detached as a bud, which develops directly 

 into an organism like its ancestor ; this is called gem- 

 mation, (c) In the third mode small particles FIG. 2. 

 called eggs arise from the tissues of the 

 parent, and on being fertilised, are capa- 

 ble of developing into new individuals ; 

 this is called ovulation. 



The second stage of existence having 

 for a time continued, the organism reaches 

 a third stage, in which waste exceeds 

 repair, and as, by degrees, the assimilated 

 material becomes insufficient to keep up Gemmation ; n 

 the processes of life this stage terminates Hydra viridit. 

 in death. 



Summary. Animals consist for the most part of 

 protoplasm, are constantly undergoing waste, and 

 being built up by the assimilation of food. They 

 differ from plants in being usually capable of loco- 



