SILVER FISHES 



121 



wings rendered activity in the early or larval stage less 

 necessary, for the winged parent could now lay her eggs 

 more easily in places where food of the right sort was 

 plentiful. Then the larva in many cases became soft-bodied 

 and short-legged, or even lost its legs altogether. The fly 

 and the larva came in the more specialised insects to differ 

 so greatly from one another that the body had to be com- 

 pletely recast when the larva changed to a fly. A resting- 

 stage thus became necessary, especially where the fly had 

 come to adopt a different mode of feeding (see p. 248). The 

 resting or pupal stage is no doubt the last-acquired of the 

 stages of an ordinary insect's life-history. 



The events which I have related, and the steps by which 

 insect-transformation was at length attained, may seem 

 to you difficult of proof. Unfortunately I cannot lay 

 before you the whole of the evidence, but I can mention 

 one fact which will help to persuade you of the substantial 

 truth of the explanation just given. Among existing 

 insects all the steps by which complete transformation is 

 supposed to have been attained can still be found. 



It will make this more evident to set down in a table 

 the life-histories of five different sorts of insects. 



It gives one matter for reflection to know, as we do, that 

 the cockroach of our kitchens has existed with little change 

 since the time when our coal-fields were laid down, and 

 that the silver fishes are still more ancient and more 

 primitive. 



