216 GENERAL BIOLOGY 



way in the physical make-up of the germinal sub- 

 stance. Whatever this substance may be, it, with 

 its accompanying potentialities, is spoken of as the 

 Inheritance of the individual. The term Heredity 

 is applied to the larger phenomenon, by virtue of 

 which such genetic resemblances universally occur 

 among organisms. Inheritance is concrete, heredity 

 is abstract. 



Individual Heredity and Racial Heredity. All 



the individuals of any given sort of animal or plant 

 resemble one another more or less closely, else we 

 would not be able to group them together. For 

 instance, all white oaks look sufficiently alike so 

 that we may distinguish them easily from other 

 oaks. In the same way, the physical characteristics 

 of a Chinese or an Englishman are sufficiently pro- 

 nounced so that either race is easily recognizable ; 

 yet the similarities that class them both as human 

 beings, on the one hand, and the peculiarities that 

 distinguish them as individuals, on the other hand, 

 are equally evident. There are grades or degrees 

 of physical resemblance which correspond, in general, 

 with the closeness or remoteness of relationship of 

 individuals or groups. 



The reason that this is so, is that the characteristics 

 of an individual are not alone its inheritance from 

 two parents, but also from a great number of grand- 

 parents and other ancestors many generations back. 

 It is obvious that there must be much mixing and 

 intercrossing in the remote parentage of any indi- 



