THE PROCESS OF HATCHING IN CORYDALIS 

 CORNUTA LINN. 



Roger C. Smith, Ph. D., 

 U>. S. Entomological Laboratory, Charlottesville, Va. 



A study of the manner of hatching of Corydalis cornuta was 

 made to ascertain if there were an egg burster used. Dr. C. V. 

 Riley (1876) stated in his observations on the life history of 

 Corydalis cornuta Linn that "the egg burster* has the form 

 of the common immature mushroom and is easily perceived 

 on the end of the vacated shell." This note was repeated in 

 his ninth annual Missouri Report, 1877 (p. 127). This is the 

 only published account of hatching known to the writer, but 

 in part has been quoted by many writers since its appearance. 

 Through the kindness of Professor A. N. Caudell, of the National 

 Museum, an abundance of preserved material was made avail- 

 able for study. Throughout the month of July of the current 

 year, a large number of egg masses of Corydalis cornuta were 

 found along a small stream near this laboratory on rocks in 

 the stream and on several overhanging trees. Some were taken 

 to the laboratory and observed for hatching. 



There appears to be no doubt that Professor Riley mis- 

 interpreted a rather unusual shaped micropyle (Fig. 1) for an egg 

 burster as suggested by Davis (1903). This micropyle, as is 

 generally the case, is located at one end of the elliptical egg 

 and in the Sialidae, to which Corydalis belongs, has somewhat 

 the shape of certain mushrooms in the button stage. It is 

 attached to the exterior of the chorion and not to an inner 

 structure as might be expected if it were an egg burster! It was 

 not observed to serve any purpose whatsoever in hatching. 



Professor Riley states further that egg bursters are generally 

 if not always a part of the ambion (amnion, perhaps). This 

 until relatively recently, perhaps to Heymon's work, 1906, 

 appears to have been the prevailing opinion concerning egg 

 bursters and we find in literature statements many times regard- 

 ing the molting of the amnion at hatching. 



* I am not aware that this special structure has been named. It is generally 

 if not always, a part of the ambion, and common to many insects, though varying 

 much in form. It may be known as the ruptor ovi. Dr. Hagen has called it the 

 "egg burster," while erpetologists designate as "egg tooth," a structure having 

 the same purpose. 



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