PROCEEDINGS OF THE COTTESWOLD CLUB 55 



appliance of science reveal to us the reason of, nor the 

 manner of, nor the operation of those changes. 



1 turn now to another part of my subject. It is 

 interesting to us naturalists to know what is the relative 

 quantity of air consumed by insects in their three states, 

 their power of existence in certain media, and the relation 

 which this power and the consumption of air bear to the 

 comparative volume of the structures concerned. It is 

 obvious that only two or three examples can be referred 

 to on the present occasion. In larvae we find that 

 respiration in the very early stages of existence is feeble, 

 but the circulation is quicker; the amount of food 

 required is, of course, less, though in proportion to the 

 size of the individual it is enormous ; ' the generation 

 of heat is less than at a later period. In the next or pupa 

 or hibernating stage respiration is very much less in 

 frequency and volume, circulation slows down, no food 

 is taken, and the temperature is consequently much 

 diminished in degree. In the imago, or perfect insect, all 

 functions, as we might expect, are working at their full 

 power, with this exception — that the need of food is, in 

 most cases, if not all, not nearly so great as in the case 

 of the larva. Many caterpillars eat daily twice their 

 weight of leaves, and by a simple arithmetical process we 

 conclude that this is as if an ox weighing say 60 stone, 

 as exhibited, would require about ^-ton of grass in 24 

 hours, or a man w^eighing 12 stone, something like three 

 cwt. of food. The larvae of flesh flies or maggots — 

 commonly so called — in 24 hours become two hundred 

 times heavier than they were. I mention these facts 

 because I think they have a distinct bearing on my 

 subject. We see the very extraordinary capacity of insects 

 in the larval state, and the, in most cases, absence of any 

 nutriment from outside in the pupal and succeeding state. 

 The voracious caterpillar had, in fact, to lay up in store, 

 in the most condensed form possible, for succeeding 



