SEASONAL DIMORPHISM OF LEPIDOPTERA. 173 



not contained in asci ; but it is evident that this fungus belongs 

 to an inferior group to those found on Pierids and Satyrids. I 

 have found them on males of Lyccena hellargus, L, corydon, and 

 L. icarus, all brightly-coloured species in comparison with L. 

 argiolus, L. minima, and L. astrarche, from which they are 

 apparently absent. 



The relationship between parasite and host seems to be 

 something more than ordinary parasitism. I have pointed out 

 that, with the exception of L. sinapis, which has no parasite, the 

 males of the British *' whites " have fewer black scales than the 

 females, the reverse being the case in regard to L. sinapis; so 

 also with the '* blues," the infested species are those that are 

 considerably more brilliant than those not infested ; the inference 

 being that the fungus, by assimilating carbonaceous matters 

 present in the excretory products of the butterfly that would 

 otherwise be deposited in the wing-scales, tends to make the 

 ** whites" whiter, and the "blues" brighter than they would 

 otherwise be. Fungi, unlike other plants, exhale carbonic acid, 

 so a considerable amount of carbon must ultimately be eliminated 

 from both the host and parasite. If this suggestion is correct, it 

 is a case of symbiosis between butterfly and fungus ; in any case, 

 students of variations occurring in these groups will have to take 

 into account that at least some part of the variation is due to 

 the presence or absence of these parasites. 



3, Halifax Koad, Cambridge. 



[We understand from Mr. Rickard that he has continued his 

 investigations of these butterfly "fungi," with the result that his 

 original conclusions are confirmed. He writes, " As a matter of 

 fact, I am cultivating the spores between glass- slips ; some have 

 already germinated ! " — Ed.] 



NEW EXPERIMENTS ON THE SEASONAL DIMORPHISM 

 OF LEPIDOPTERA. 



By Dr. August Weismann. 



(Translated from the German by W. E. Nicholson, F.E.S.) 



(Continued from p. 157.) 



VI. Experiments with Vanessa urtic^e. 



First experiment ivith urticce, 1886. — Two nests of young 

 larvae, taken before the second moult (when 4 mm. long), were 

 reared in the incubator at 27° C, 30° C, after July 2nd. The 

 larvae grew with astonishing rapidity, and pupated between 

 July 3rd and 5th. 



