176 THE HISTORY 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. 11. 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 
