So DARWINISM TO-DAY. 



agents decided for them in immature, i. e., egg, larval, or 

 pupal, life, and this immature life is in most cases by far 

 the larger part of the insect's duration of existence. 



Henslow 14 sowed together the same quantity of two 

 kinds of wheat in a square yard of ground. The young 

 wheat plants that came up were many times as many as the 

 soil could support ; the passive struggle for life was intense. 

 In the end twenty heads ripened and these were all of one 

 of the two kinds sown. The experiment was repeated in 

 the following year with the same result. In the struggle 

 one kind of wheat had a distinct advantage over the other. 

 But this selection depended wholly on special characters or 

 strength of the young stages. None of the adult characters 

 cut any figure in this selection, which was decided before 

 ever the plants came to maturity. And this is true, it seems 

 to me, of most of struggle and selection. 



It is not in the adult state that the oppressive abundance 

 exists : in the forest to-day are about as many crows as last 

 year ; in the meadows as many yellow butterflies as in sum- 

 mers by. The eggs and the young are the stages which 

 figure in mortality tables. They need the variations and 

 adaptations ; the pressure is largely gone before maturity is 

 reached. However, the adaptations of the fully-developed 

 body, in structure and function, certainly do not fall behind 

 those of the embryonic and immature stages. Indeed they 

 obviously are more complex and perfected. 



But after all what determines just what millions of trout's 

 Indiscriminate e gg s sna ^ be destroyed and what thousands 

 death, s } ia u hatch small fry ? Many a sharp-eyed trout 



fisherman, many a keen-witted nature observer, many a 

 trained biologist will answer: Chiefly chance, the luck of 

 position, the good fortune of not being devoured by the 

 roaming things that paddle or crawl in the upper reaches of 

 trout streams. What shall decide when the big whale opens 

 his mouth in the midst of a shoal of myriads of tiny 



