136 Psyche [August 



in these alkaline solutions for twenty-four hours, some of the larvae, 

 still enclosed within the vitelline membrane, protruded from the 

 egg-shells. Sometimes the posterior part of the larva within the 

 vitelline membrane protruded from the egg-shell, whereas in a 

 normal hatching the anterior end pushes forth from the egg. Of 

 the two hundred eggs emersed in the alkaline solutions, twenty- 

 seven larvse emerged from the vitelline membrane within thirty- 

 six hours, ninety-seven within forty-eight hours and thirty-three 

 within sixty hours. In the experiment with the alkaline juices 

 regurgitated from the digestive tract of the army worms, the eggs 

 began to hatch in less than a minute, and ninety-seven of one hun- 

 dred eggs hatched within three hours. 



Eggs w^ere now emersed in distilled water and results were ob- 

 tained which were similar to those derived from the use of dilute 

 solutions of sodium hydroxide. It appears, seemingly, that in- 

 creased turgidity causes the larvae to emerge when the eggs are 

 emersed in water or dilute alkaline solutions for thirty-six hours 

 or longer. 



Is there a physiological mechanism connected with the hatching 

 of Chcetoga'dia monticola? A little pressure exerted upon the eggs 

 of this tachinid causes the maggot enclosed by the vitelline mem- 

 brane to issue from the chorion apparently uninjured. If the 

 larvse within the vitelline membrane is emersed in the liquid exuded 

 from the mouths of army worms, the process of hatching can 

 readily be observed under a microscope. As soon as the maggot 

 enclosed within the vitelline membrane is emersed in the liquid 

 exuded from the mouths of the army worms, bodily contractions 

 can be observed, in a minute or less the contractions become more 

 energetic and one can readily see the segments move from the pos- 

 terior to the anterior end of the larva resembling a peristalic 

 movement. Next the larva turns the anterior end towards the 

 flattened or attached side of the egg so that the jaws are near the 

 posterior end of the abdomen. The maggot then attempts to cut 

 the vitelline membrane with the sickle-shaped part of its jaws. 

 Often the distal end of the jaws appear to slip on the inner surface 

 of the membrane, but once the end of the jaws is pushed through 

 the vitelline membrane, a single sweep of the head, and the jaws 

 cut a longitudinal incision, through which the maggot makes its 

 way out. In pushing out of the egg-shell, peristalic movements 

 of the body segments are again evident. 



