( lxix ) 



During late autumn, winter, and early spring, those reared 

 by myself were fed for the most part on cabbage and brussels 

 sprouts with some admixture of dock. During the summer 

 the larvae were supplied with various low plants as* well as 

 sallow and willow, but no cabbage. 



The imaginal life of the species is long with healthy 

 specimens, varying according to conditions of temperature 

 and moisture from three weeks to a month in the summer, 

 and considerably longer during the winter — of course within 

 doors — the females being longer lived as a rule than the 

 males. 



Pairing in my experience does not take place in less than 

 a week from date of emergence under the most favourable 

 circumstances (warm moist summer weather) with the males, 

 and from two to three weeks in the case of the females. In 

 one or two instances the early death of the specimen selected 

 for male parent necessitated the careful choice of a second as 

 nearly identical with the first as possible, in one case that of 

 Brood C 2, a third male had to be introduced, fortunately 

 owing to the peculiarity of the pairing habit above referred 

 to, and the fact that the replaced males became paralyzed or 

 died within two or three days of emergence, I feel quite 

 confident that only the one pairing took place. 



The experiment was not made in the first place with a view 

 to testing the Mendelian theory, but in order to ascertain the 

 relative proportions of melanic to non-melanic forms, and the 

 possible range of variation to be obtained from a single pair. 

 Apart from the relative strength or weakness of the melanic 

 strain the heredity from parents to offspring would seem to 

 be very strict, and this result is quite in conformity with 

 previous experiments conducted with the same species, and 

 also with other Noctuid moths in which great diversity of 

 forms can be obtained from a very restricted area. This 

 purity of strain suggests how easily a series of local races 

 developing into sub-species might be caused by isolating 

 factors such as diverging habits, etc. 



But the result is in contrast with experiments in rearing 

 broods of Malacosoma castrensis when a very wide range of 

 forms was obtained from a single batch of eggs or from a 



