312 SOCIAL LIFE IN THE INSECT WORLD 



their innumerable nervures. If not perfect, at least the 

 general plan is complete, with all its innumerable details. 

 To expand these miserable bundles and convert them 

 into an ample set of sails it is enough that the organism, 

 acting like a force-pump, should force into the channels 

 already prepared a stream of humours kept in reserve 

 for this moment and this purpose, the most laborious of 

 the whole process. As the capillary channels are pre- 

 pared in advance a slight injection of fluid is sufficient to 

 cause expansion. 



But what were these four bundles of tissue while still 

 enclosed in their sheaths ? Are the wing-sheaths and the 

 triangular winglets of the larva the moulds whose folds, 

 wrinkles, and sinuosities form their contents in their own 

 image, and so weave the network of the future wings and 

 wing-covers ? 



Were they really moulds we might for a moment be 

 satisfied. We might tell ourselves : It is quite a simple 

 matter that the thing moulded should conform to the 

 cavity of the mould. But the simplicity is only apparent, 

 for the mould in its turn must somewhere derive the 

 requisite and inextricable complexity. We need not go 

 so far back ; we should only be in darkness. Let us keep 

 to the observable facts. 



I examine with a magnifying-glass one of the triangular 

 coat-tails of a larva on the point of transformation. I 

 see a bundle of moderately strong nervures radiating 

 fan-wise. I see other nervures in the intervals, pale and 

 very fine. Finally, still more delicate, and running trans- 

 versely, a number of very short nervures complete the 

 pattern. 



Certainly this resembles a rough sketch of the future 



