ON THE GENETIC VIEW OF NATUEE. 333 



ensure the multiplication, what are those which check 

 the increase, of population ? As all living things are 

 dependent on each other, forming the great household or 

 economy of nature or the smaller one of human society, 

 a certain adjustment must exist by which a definite place 

 and part are allotted to every individual and to every 

 class of individuals. Malthus had studied the problem 

 from a political point of view. Here it was felt to be 

 of human and social importance, but his principle was 

 applicable to all living creatures. For everywhere, even 

 in the remotest and only recently discovered countries, 

 we see at work the luxuriant and productive powers of 

 nature on the one side, on the other side the many 

 difficulties and obstacles by which they are forcibly and 

 automatically kept in check, resulting in the ever-recur- 

 ring spectacle of a " struggle for existence." The more 33. 



"Struggle 



we penetrate into the hidden and remoter provinces of for exist- 

 ence. 



nature, into the luxuriant " fauna and flora " of tropical 

 regions, or realise the enormous population among the 

 lower forms of life, the more the conviction forces itself 

 upon us that the apparent equilibrium is only maintained 

 by the phenomenon of " crowding out " on a scale com- 

 pared with which the spectacle unfolded by Malthus in 

 his special application to human societies is quite a minia- 

 ture display. This process of " crowding out " must have 

 been at work during the untold ages which modern 

 geology has made known to us, and the effects of it 

 must indeed have been extraordinary, and well worthy 

 of study. That living beings, if left to their natural 

 instincts, multiply at an enormous rate, and would, 

 except for certain automatic checks, in a very short time 



