SEASONAL DIMORI^HISM OF LEPlt)OPTERA* l05 



similar to the summer form of napi. Had this case only 

 occurred once, it might have been thought that an egg of 

 P. napi, or a quite young larva, had been accidentally introduced 

 into the experiment with the food-plant. I cannot declare it 

 absolutely impossible, notwithstanding careful searchings of the 

 food; but I do consider it very improbable, since the intro- 

 duction of an egg must have taken place the first day of the 

 rearing, otherwise the larva of napi would be far behind the 

 brood of hryonice in development ; but on the first day the 

 quantity of food is so small, that the oversight of an egg or a 

 young larva on it is scarcely conceivable. 



But it may yet be added, that one of the pupae of Experi- 

 ment II. forced in the incubator exhibited a sprinkling of the 

 wings with white, which may be interpreted as a partial rever- 

 sion to the napi-foi'm. This would contradict my view given in 

 1871, which regarded the form hryonice as the original parent 

 form of napi. It is obvious that it is a very old form from its 

 wide distribution — in the high Alps and in the far north ; but we 

 must, indeed, withhold the final cause, until numerous further 

 extensive experiments are before us. If possible falsification of 

 the experiments is disregarded, the quite isolated 7iapi4oYma 

 which arose cannot be explained otherwise than by reversion. 

 The white-sprinkled female of hryonice might be a hermaphrodite, 

 similar to the hermaphrodite bees, in which the male and female 

 characters sometimes appear intermixed in a wild state. Un- 

 fortunately this view can no longer be decided by anatomical 

 examination, as the butterfly is dry. But the 7iapi-\ikG males 

 might have their origin in an earlier crossing which once took 

 place between a hryonice female and a napi male, and therefore 

 exhibit no variation from napi. A mixture of both forms is not 

 entirely impossible, although in general they fly separated both 

 as regards time and place ; but there certainly are many places, 

 in which they overlap one another in both aspects.* But if this 

 was the cause of these isolated specimens of napi in my experi- 

 ments, the same would have arisen without the operation of an 

 abnormally high temperature — so it may be thought. The 

 question is obviously not ripe for decision ; further experiments 

 with larger numbers of individuals must be undertaken, and 

 attention must be specially directed to this point. 



III. Experiments with Vanessa levana-prorsa. 



Since the publication of a series of experiments with this 

 species in the year 1871, I have again repeatedly experimented 

 with it, whenever the material was available. Before everything 

 the point with me was to test the results I had already obtained 



j;< Thus Meyer-Diirr cites the neighbourhood of Meyringen as a place in 

 which an exactly intermediate form between na;pi and hryonice occurs* 



