(2 vit.--) 
characters noted in this paper. A discussion ensued, in which 
Mr. Elwes, Mr. Poulton, Mr. Champion, and Mr. Merrifield 
took part. 
Dr. F. A. Dixey communicated a paper entitled ‘‘On the 
Phylogenetic Significance of the Variations produced by 
Differences of Temperature on Vanessa atalanta.” In this 
paper he pointed out that Mr. Merrifield’s specimens, which 
had been exposed as pup to unusual temperature-conditions, 
showed marks of reversion to older forms. This was the case 
with both the ‘‘ warmed” and the ‘‘ cooled” specimens, but 
the ancestral marks differed under the two conditions, the 
latter showing a further degree of reversion than the former. 
A possibility was thus suggested that while more than one 
kind of disturbance is capable of inducing reversion, the 
extent to which reversion takes place may vary with the 
nature of the disturbance. Other unusual features visible in 
the same specimens did not seem to have any ancestral 
significance, and were perhaps direct results of the altered 
conditions of temperature. 
Dr. Dixey further remarked that he considered the peculiar 
interest of Mr. Merrifield’s experiments with V. atalanta lay in 
the fact that this species is monomorphic and not very variable, 
the forms produced under altered conditions of temperature 
being older than any now extant (except as occasional aberra- 
tions). The results obtained by Weismann with A. levana 
and P. napi, and by Edwards with P. aja, differed from Mr. 
Merrifield’s in the fact that they were confined to the artificial 
production of the oldest of two or more normally existent 
forms of a polymorphic species. 
In conclusion Dr. Dixey stated that Weismann had already 
advanced reasons for concluding that unusual heat as wellas 
cold was capable of inducing reversion, but that the ancestral 
characters thus revived should be different under the two 
different antecedent conditions appeared to be a new and un- 
expected phenomenon. 
The President, Mr. Merrifield, Mr. Poulton, Dr. Chapman, 
and Mr. Tutt took part in the discussion which ensued. 
