PHENOMENA OF INHERITANCE 195 



On the other hand many resemblances and 

 differences between parents and offspring are 

 due not to heredity at all, but to environ- 

 mental conditions. By means of experiment 

 it is possible to distinguish between hereditary 

 and environmental resemblances and differ- 

 ences, but among men where experiments are 

 generally out of the question it is often diffi- 

 cult or impossible to make this distinction. 



I. HEREDITARY RESEMBLANCES 



1. Racial Characters. All peculiarities 

 which are characteristic of a race, species, 

 genus, order, class and phylum are of course 

 inherited, otherwise there would be no con- 

 stant characteristics of these groups and no 

 possibility of classifying organisms. The chief 

 characters of every living thing are unalter- 

 ably fixed by heredity. Men do not gather 

 grapes of thorns nor figs of thistles. Every 

 living thing produces offspring after its own 

 kind. Men, horses, cattle; birds, reptiles, 

 fishes; insects, mollusks, worms; polyps, 

 sponges, micro-organisms, all of the million 



