130 MAN, — THE ANIMAL 



that are subject to disease. The unicellular forms 

 of life become sick and die In unnumbered 

 thousands. Grasshoppers have been noticed to 

 die In great numbers and frequently some epi- 

 demic attacks all of the fish in a lake or pond and 

 the shores become littered with their dead bodies. 

 More facts might be marshaled but enough 

 have been stated to warrant the conclusion that 

 disease is of common occurence in all forms of life 

 and that man thus forms no exception. Some of 

 the recent paleontological Investigations reveal 

 that animals were subject to parasites, and hence 

 disease, in the age of molluscs and fishes. (Figs. 



42-43-) 



In order to make this study of disease reveal 



something of the fundamental nature of life, we 

 must inquire into a few of Its details. 



It makes but little difference where one begins 

 his study. In what group of plants or of animals. 

 Take the common dandelion which many of us 

 regard as a weed and a pest In the lawns. It is 

 generally distributed In open lots and along the 

 sidewalks in the uncared-for parts of most cities. 

 The typical and normal plant has a round flower 

 stalk and a symmetrical blossom. If one ex- 

 amines more closely the flowers of a number of 

 speclments, there will be found some with a wide, 

 flat flower stalk supporting an irregular over- 



