GRAPTA INTERPvOGATIONIS. 



ON THE EFFECT OF COLD APPLIED TO THE CHRYSALIDS OF GRAPTA 



INTERROGATIONIS. 



Interrogationis has proved susceptible to the influence of cold. In Psyche, 

 Vol. Ill, p. 15, 1880, I related this at length. The same account was given in 

 the Appendix to Weismann's " Studies in the Theory of Descent," Part I, p. 149, 

 1880, London. I have thought it well to publish Plates of the species affected, 

 showing the changes brought about, and the present is the first of the series. 

 Figs. 1, 2, show the upper sides of the normal male and female. Figs. 3, 4 J 5 ? , 

 changed examples. Eggs of form Urnhrosa were obtained from females in con- 

 finement, June, 1879. As the chr^salids formed, at intervals of from six to 

 twenty hours after pupation, they wei'e placed in the ice-box. At fourteen 

 days, all but five were removed, these being left six days longer. Several were 

 found to be dead at the end of the fourteen days. The temperature most of the 

 time was about 35° Fahr. (1.7° C), but a little higher each day, as the ice melted, 

 reaching then 40° to 45° Fahr. (4° to 7° C). From the first lot were obtained 

 seven perfect butterflies, 3 J 4 ? , from the twenty-day lot five, 4 J 1 ? . All 

 were form Umhrosa, and nearly all had been changed in one striking particular. 

 In the normal Umhrosa of both sexes, the fore wings on upper side have, on the 

 costal margin next inside the broad border of the hind margin, and separated 

 from it by a considerable space of fulvous, a dark patch which ends a little 

 below the discoidal nervule ; inside the same border, at inner angle, is a similar 

 patch, lying on the submedian interspace. Between these two patclies, across 

 all the median interspaces, the ground is fulvous, but very slightly clouded with 

 black, often so slightly that it would not be noticed. Now, in all four of the 

 females exposed to cold for fourteen days, there is present a broad black band 

 which crosses the entire wing, continuous, of uniform shade, covering the two 

 patches as well as the intervening clear space, and almost confluent with the 

 marginal border from end to end, only a streak of obscure fulvous anywhere 



