Dimorphism and PolymorpMsin in Butterfiies. 35 



plants, but only upon the flowers, and as the flowering 

 time of most plants is limited to a comparatively short 

 period of the summer the successive broods have to seek 

 different food plants. In "West Virginia, according to 

 Mr. Edwards, they feed in the Spring on the flowers of the 

 Dogwood (Cornus). In June and July the larvas feed on 

 the flower buds of the Rattle-weed (Cimicifuga Eacemosa), 

 and later in the season on Actinomeris Squarrosa. 



Mr. Edwards noticed that the caterpillars varied some- . 

 what in colour according to the food plant and this 

 might doubtless affect the shade of colour of the resulting 

 butterfly. 



In regard to the results of these variations it seems 

 probable that we have here species actually forming 

 before our eyes. 



In the case of the Spring Azure, Mr. Edwards found 

 that there was only the very slightest connection between 

 the large typical Pseudargiolus and the form Violacea, 

 and that if the few straggling specimens of the form 

 Neglecta which emerge late in the summer, instead of 

 hibernating in the chrysalis stage and producing Pseudar- 

 giolus in the following May, were suppressed, the separa- 

 tion would b6 complete and we should have two species 

 instead of one. 



In the case of Grapta Interrogationi'S, the separation 

 has gone so far that were the males of each form to mate 

 only with females of like form, the species would be 

 permanently divided into two. 



Species forming, however, is slow work and none of us 

 can see but a very short way along the path, but to those 

 who have the eyes to see, even the slight glimpse which 

 we can get is most interesting, and we know at least that 

 the great creative process is still going on according to 

 the natural laws laid down by the great Architect of the 

 Universe. 



