51 



shell. It follows the shell thus down the side, across the bottom and 

 up the other side, until the anal prolegs at the posterior end of the 

 body are just beneath the head. The embryo, in making its escape, 

 bites viciously with its mandibles at the hard, tough membranes of 

 the Qgg, and gradually the spot weakens and the head of the larva sud- 

 denl}^ bursts through. It can now easily enlarge the hole until it is of 

 sufficient size to crawl through. Once this is done, the larva is free 

 from the egg in about two minutes. The whole process, from the 

 first attempt to pierce the egg membrane until the larva is excluded, 

 requires but a few minutes. In two cases where the exact time was 

 noted it was thirteen and sixteen minutes, respective!}^. 



The exit hole is usually large, with very ragged edges, situated on 

 one side of the egg between the base and apex. The empty shell is of 

 a translucent white, with a distinct purplish iridescence seen in cer- 

 tain lights, more especially when viewed against a dark background. 

 It retains its original shape. 



SHRINKING OF INFERTILE EGGS. 



The changes in external appearance undergone by infertile eggs are 

 sufficient!}^ different from those of normal fertilized ones to merit sep- 

 arate mention. One fact is important. From thousands of infertile 

 eggs laid by moths in the laboratory not a single one ever hatcht d or 

 showed the slightest external signs of embryonic development. Almost 

 as soon as they are laid infertile eggs acquire a distinctly yellowish 

 color, and within a few hours begin to shrivel up. After twenty-four 

 or thirty -six hours they are always greatly shrunken and are acquir- 

 ing a dusky color. From the very first they are higher and more 

 conical than the normal eggs, this shape being accentuated by the 

 shrinking, which occurs principally in an equatorial direction. 



EATING OF SHELLS AND EGGS BY NEWLY HATCHED LARV^. 



In the great majority of cases the newly hatched bollworms do not 

 go immediately in search of food, but turn their attention to the 

 deserted eggshell. Not content with the portion already gnawed out 

 in their attempts to escape, they start anew to eat the shell. This 

 may last only for a few minutes, or, again, may continue for nearly 

 an hour. Frequently the entire shell is consumed, although often 

 only one-half or three-fourths of it is eaten. What may be the benefit 

 derived from eating the tough chitinous shell is rather uncertain. 

 The idea that the larva derives any nourishment therefrom, or that it 

 destroys the shell to remove traces of its own presence on the plant, 

 can hardly be accepted. Nevertheless, the eating is a very constant 

 habit. 



After this is done the larva begins wandering about in its search for 

 food. Quite often in captivity, when large numbers of eggs are close 



