176 THE HISTOKY OF CREATION. 



and which may be traced to other processes of life — the 

 functions of propagation and nutrition. All the different 

 forms of organisms, which people are usually inclined to 

 look upon as the products of a creative power, acting for a 

 definite purpose, we, according to the Theory of Selection, 

 can conceive as the necessary productions of natural selec- 

 tion, working without a purpose, — as the unconscious inter- 

 action between the two properties of Mutability and 

 Hereditivity. Considering the importance which accordingly 

 belongs to these vital properties of organisms, we must 

 examine them a little more closely, and employ a chapter 

 with the consideration of Transmission by Inheritance. 

 (Gen. Morph. ii. 170-191). 



Strictly speaking, we must distinguish between Heredi- 

 tivity (Transmissivity) and Inheritance (Transmission). 

 Hereditivity is the power of transmission, the capability of 

 organisms to transfer their peculiarities to their descendants 

 by propagation. Transmission by Inheritance, or Inheritance 

 simply, on the other hand, denotes the exercise of the 

 capability, the actual transmission. 



Hereditivity and Transmission by Inheritance are such 

 universal, everyday phenomena, that most people do not 

 heed them, and but few are inclined to reflect upon the 

 operation and import of these phenomena of life. It is 

 generally thought quite natural and self-evident that every 

 organism should produce its like, and that children should 

 more or less resemble their parents. Heredity is usually 

 only taken notice of and discussed in cases relating 

 to some special peculiarity, which appears for the first 

 time in a human individual without having been inherited, 

 and then is transmitted to his descendants. It shows 



