48 Effects of Alcohol on Helema hWuimri'd 



noteworthy and unexpected way. I mentioned above that the race of 

 Selenia bilunaria with which we are concerned was double brooded, but 

 I did not then indicate that it was seasonally dimorphic ; such, never- 

 theless, is the case. The spring brood consists of larger, heavily and 

 richly pigmented individuals, whilst the summer^ brood is smaller and 

 very weakly provided with pigment when compared with its spring 

 relatives. This difference is caused directly by the longer growth period 

 of normal autumnal larvae (which produce the spring imagines) lending 

 itself to the production of larger, sturdier pupae. In spite of the cir- 

 cumstance that the two broods including a treated example in their 

 parentage actually fed up more quickly than the controls, they exhibit 

 in most of their members a facies exceedingly close to that of an 

 ordinary spring brood insect for they possess all its depth and richness 

 of coloration — an occurrence depending immediately on their superior 

 size and vitality. The controls, on the contrary, are smallish specimens 

 differing in no respect from the washed out looking July brood which 

 Haworth called juliaria. 



In the progeny of Stockard's alcoholised guinea-pigs one of the most 

 striking things was the development of individuals malformed in respect 

 to various organs, but more especially in the eyes. In the case of these 

 insects now being discussed, no such abnormalities presented themselves ; 

 all of the imagines, no matter what their parentage, were equally per- 

 fect in all of their organs. 



The sex ratios in all cases call for no comment although in all, 

 exactly as in the broods from which their parents were derived, an 

 excess of females appears. 



IV. Discussion of the Results. 



To summarise the results we may state : 



(1) The offspring of treated parents neither included monstrosities 

 nor displayed even slight abnormalities. 



(2) No new hereditable variations occurred. 



(3) The survivors of the treated batch grew, on the average, 

 decidedly larger than their untreated relatives. This may have arisen 

 simply from the elimination of the weaker individuals by the deleterious 

 agent employed, or it may have been caused by some physiological action 

 of the ethyl alcohol. In any case it agrees with Pearl's experience with 



1 Should, by chance, three broods appear in one season the third resembles, in every 

 respect, the second or normal summer brood. 



