ADVANTAGEOUS CHARACTERS TRANSMITTED. 1 65 



existence, favour some individuals and prejudice others. The 

 favoured individuals will gain the victory over the others, 

 and while the latter perish more or less early, without leav- 

 ing any descendants, the former alone will be able to survive 

 and finally to propagate the species. As, therefore, it is 

 clear that in the struggle for life the favoured individuals 

 succeed in propagating themselves, we shall (even as the re- 

 sult of this relation) perceive in the next generation differ- 

 ences from the preceding one. Some individuals of this 

 second generation, though perhaps not all of them, will, 

 by inheritance, receive the individual advantage by which 

 their parents gained the victory over their rivals. 



But now — and this is a very important law of inheritance 

 — if such a transmission of a favourable character is con- 

 tinued through a series of generations, it is not simply trans- 

 mitted in the original manner, but it is constantly increased 

 and strengthened, and in a last generation it attains a 

 strength which distinguishes this generation very essentially 

 from the original parent. Let us, for example, examine a 

 number of plants of one and the same species which grow 

 together in a very dry soil. As the hairs on the leaves of 

 plants are very useful for receiving moisture from the air, 

 and as the hairs on the leaves are very changeable, the 

 individuals possessing the thickest hair on their leaves will 

 have an advantage in this unfavourable locality where the 

 plants have directly to struggle with the want of water, and 

 in addition to this have to compete with one another for 

 the possession of what little water there may be. These 

 ' alone hold out, while the others possessing less hairy leaves 

 perish ; the more hairy ones will be propagated, and their 

 descendants will, on the average, be more distinguished by 



