104 THE ENTOMOLOGIST. 



Inasmuch as at this temperature not one of the species examined 

 developed the perfect insect, it would have been theoretically 

 possible to vary the period of exposure at pleasure ; the prac- 

 tical result, however, showed that in the case of most species 

 employed the possible duration of exposure had well-defined 

 limits. 



A second portion of each brood was allowed to develop the 

 perfect insects at the normal temperature of the room ; a careful 

 control-experiment seeming to be desirable. 



A third portion underwent development at a raised tempera- 

 ture. I must here offer my special thanks to Dr. Stebler, 

 Director of the Agricultural Laboratory of the Federal Poly- 

 technicum, for not only placing some of the apparatus of the 

 Station at my unconditional disposal, but also for having it 

 especially prepared for my object. The apparatus made use of 

 by me, the temperature of which was very easily regulated, was 

 fitted with glass doors, which enabled the light to enter freely. 



Let us now turn to the most essential features of the results 

 obtained in the case of those species which were subjected to 

 experiment in large or at least considerable numbers. 



1. P. macJiaon, L. (Larvte from Zurich.) 

 a. Warmth. 

 From 17 pups kept at 37° C. (98^—99° F.), I obtained, in 

 7 — 10 days, 15 well-developed perfect insects. Ujjper surface. — 

 The general colouring is much lighter than in the normal second 

 brood in this locality, in consequence of a strong yellow powdering 

 of the black patch at the base of the fore wings, of the toothed 

 outer band, and of the four first ribs reckoned from the dorsal 

 border.* The blue band of the hind wing is further removed 

 from the margin, and in 50 per cent, of the specimens one or 

 two of its projections reach the black arch that closes the central 

 cell ; this being otherwise exclusively characteristic of forms of 

 much more southerly origin. The fore wing is strongly curved, 

 the hind wing has its outer margin deeply indented between the 

 ribs, and is furnished with a conspicuously elongated tail (with 

 an expansion of 76 millim. the tail measures 10 millim.). Our 

 Zurich summer form has, with the same expansion, a tail only 

 two-thirds as long. With this conspicuous modification in the 

 form of the wing is evidently connected the enlargement of the 

 yellow marginal crescents on the outer border. The abdomen 

 assumes a prevailing yellow tint, the black lateral lines becoming 

 much reduced throughout, and in two examples being entirely 

 obliterated by a yellow powdering. In the same way the black 

 stripe on the back of the abdomen is more or less lost, in two 



''■ N.B. — The " dorsal" border iu Dr. Standfuss's paper=what is usually 

 called in this country. the "inner" or "posterior" border. 



