( ee?) 
the germ-plasm itself. If all could be shown to be hereditary, 
it would seem to follow that the supposed influence upon the 
struggle of the ids was really inoperative, but the issue would 
still remain open between pangenesis and a direct modifica- 
tion of the determinants in the germ-plasm. If some, as 
seemed probable, turned out to be non-transmissible, the 
effect might be tried of varying the period in the ontogeny 
during which the disturbance was applied, with the view 
of ascertaining whether the intervention of new conditions 
at different stages of the struggle of the ids would not 
produce different results. 
In conclusion, Dr. Dixey pointed out the importance of a 
well-established phylogeny as a basis of investigation, since 
ib was only in groups of which the phylogeny was known that 
the ancestral character of these variations could be pro- 
nounced upon with certainty. For many reasons the 
Lepidoptera formed a peculiarly suitable group for such 
experiments, which might fairly be expected to throw much 
additional light on the complex subject of heredity. 
Colonel Swinhoe referred to Dr. Dixey’s remarks as to the 
phylogeny of Argynnis and Vanessa, and asked if he considered 
the male or the female of Argynnis niphe the older form. 
Mr. Hampson pointed out that the peculiar aspect of 
A. niphe $, was generally attributed to mimicry of Danais 
chrysippus, though he was not himself prepared to endorse 
that opinion. 
Colonel Swinhoe thought that the facts of the distribution 
of the two insects were not incompatible with the supposed 
mimicry. 
Dr. Dixey, in reply, said that he believed the marginal and 
apical areas of dark ground colour in A. niphe 2, were of 
more ancient origin than the tawny colour of the male. The 
special features of mimics were often retained rather than 
acquired, and whether A. niphe were a mimic or not, he 
should be inclined to consider these areas as relics of an 
ancestral feature. The evidence as to the original dark 
ground colour of Argynnis was cumulative, and he begged to 
refer to his paper in Trans. Ent. Soc. Lond., 1890, pp. 102-105, 
for a fuller discussion of the question. 
