1920] Smith: Hatching in Corydalis 73 



start the rent. The embryo pushes itself feebly upward, the 

 dorsum of the head first appearing. This upward shifting 

 continues until the sixth or seventh abdominal segment is 

 reached. During the emergence the swallowing of air bubbles 

 increases in rate. The embryo normally stops at this stage of 

 emergence for a varying period of time. It now casts off the 

 embryonic molt in precisely the same way as hatching is effected. 

 By continued swallowing of air the old cuticula is stretched 

 further. Finally the swallowing of air bubbles is discontinued 

 and the larva begins to work the abdomen forward as is done in 

 many insects at molting. As the abdomen is brought forward 

 within the old cuticula the thoracic region becomes greatly 

 .strained and finally tears over the prothorax. Immediately the 

 broad, somewhat angular prothorax appears. The setae 

 straighten up as the smooth glassy coat slips back. The thorax 

 is slowly pushed through the rent. The molt is held back by 

 the mouth parts causing the head to be turned ventrad so that 

 the larva forms a loop over the egg. 



The heavy cliitinous mandibles and abdominal hooks are 

 not shed as might be expected. This thin embryonic cuticula 

 resembles more a tight fitting sack than a true molt. It is 

 probably not attached (or is very loosely attached) to the inside 

 of the chorion at some place as in the Chrysopidae and Pentato- 

 midse for many embryos in confinement tumble from the egg 

 and fail to cast this embryonic molt. All such larvae died. 

 The legs before shedding this molt are useless and the lateral 

 abdominal filaments are bound close to the body. After the 

 molt the larvae are very active and the filaments expand to 

 their normal position. This molt lies normally in the rent of 

 the egg shell. 



The writer concludes that hatching and the first molt are 

 effected by the swallowing of air bubbles combined w4th the 

 upward pushing of the embryo. The rent in the chorion is 

 at the anterior end generally at one side of the micropyle. If 

 the empty chorion be mounted and examined microscopically 

 it will be seen that the rent is generally ragged and has the 

 appearance of being torn by internal pressure. Sometimes the 

 ■entire upper end of the egg is torn off as if it were a cap. 



The phenomenon of swallowing air bubbles to effect hatching 

 and molting has been recorded several times in literature. 



