Seasonal Dimoijiliism in Butterjlies. 199 



their correspondence therewith. These are questions that 

 must, I think, for the present remain unanswered; though 

 whatever the solution may be, there seems no need to 

 anticipate that it will weaken the case for selective 

 adaptation. 



4. Experiments and Observations in Seasonal Di- 

 morphism CONDUCTED BY Mr. G. A. K. MARSHALL, 

 F.Z.S , IN THE YEARS 189G— 1901. 



In the " Annals and Magazine of Natural History," 

 1901, ii, p. 403, Mr. Marshall writes as follows: — " Two 

 years ago I made a few experiments in applying moist 

 heat to the pupae of several species of Teracolus. Un- 

 fortunately all my notes on the subject have been lost, 

 but, so far as I can recollect, the results were almost 

 entirely negative, which I then attributed to insufficient 

 heat. The resulting specimens were, however, sent to 

 the Oxford University Museum with full data." There 

 are also in the Hope collection several other specimens, 

 collected by Mr, Marshall in 1896 and following years, 

 which are of considerable interest in their bearing on the 

 subject of Seasonal Dimorphism. By the kindness of the 

 Hope Professor, I am permitted to give Mr. Marshall's own 

 comments on both series of specimens. These are contained 

 in private letters to Professor Poulton, and have not hitherto 

 been published. I propose to arrange the notes in chrono- 

 logical sequence; but it will be seen that the experiments 

 fall into two main groups, which are more or less inter- 

 mingled in order of time. The first group of experi- 

 ments includes cases where one form of a species was 

 reared under normal conditions from eggs laid by another 

 form of the same species. In the second group of experi- 

 ments, the pupge, or sometimes the larvae in their later 

 stages as well as the pupae, were subjected to artificial 

 conditions in order to see whether any effect could be 

 thereby produced on the folloAving emergence. It is well 

 known that very striking results have been brought about 

 by artificial conditions of temperature in the case of 

 dimorphic butterflies in Europe and North America. The 

 names of Dorfmeister, W. H. Edwards, Weismann, Merri- 

 field and Standfuss, to say nothing of others, will occur to 

 everyone as those of the authorities to whom we owe nearly 



