35 



of one, but I found I had got into an entirely different field of observation, and one of a 

 most surprising character ; everything seemed to be the very reverse of what I had seen 

 in Promethea. The scales were long, fine, and of a hair-like form, strewed thinly over 

 its surface in quite an irregular manner ; the beautiful green colour so much admired in 

 the Luna, is not given off by the scales but from the membrane. The scales are yellowish, 

 and the more numerous the scales the more yellow is the tint given to the wing. Many 

 of the scales separate into branches, these branches separating' again into finer ones, re- 

 sembling some grasses we have seen. The scales around the "eye spots" are of the ordinary 

 scale formation, the membrane under the coloured scales partaking of the colour of the 

 scales. All of which goes to show that it is not safe to trust to one insect in order to get 

 reliable information about the constitution of another. 



Mr. Fenn calls attention to the usually more rapid expansion of the wings of 

 butterflies as compared with the moths. On one occasion I was looking at the chrysalis 

 of a Danais archijypus, wliich I had fastened to a door frame, a little above the level of 

 my eyes, when the pupa case burst, and the butterfly fell fluttering to the floor ; by the 

 time it had reached it the wings had attained their full length, but limp as a wet rag. 

 With what force must the fluid be injected to the very extremity of the wings to produce 

 such rapid extension ! It gives no opportunity for observing the manner of its accom- 

 plishment ; it is more like the relaxing of a compressed spring than anything else. 



For such an investigation, probably the best results could be obtained from the exam- 

 ination of a fresh pupa, secured just before emerging. 



Since completing this, I have had the opportunity of making another investigation. 



In the latter part of October I received from Dr. Woolverton a fresh chrysalis of 

 Danais archippus. I suspended it in a convenient place for observation, doubting whether 

 it would mature or not at that season of the year. On the 5th of November it still 

 retained its delicate, pellucid green colour, no perceptible change having taken place in 

 it, except perhaps that the golden spots were more conspicuous. On the morning of 

 the 6th it had become a deep, dull, bluish black ; by noon the red colour of archijypus 

 was quite perceptible through the wing-cases, and by evening its black lines and white 

 spots were distinctly seen. Jt had been maturing so rapidly that I was afraid to leave it 

 over night, least it might burst irs bonds before morning, so I gave it an alcoholic bath, 

 which arrested its progress. Next m-jrning it had an angular look, having shrunk a good 

 deal. The outer integument ijeeled ofi" freely, the pupa being well matured and firm to 

 the touch. It I'equired quite an effort to remove the winglet from the body, so com- 

 pletely had it matured. When taken off it measured nearly three-fourths of an inch in 

 length, and was a. perfect miniature of the expanded wing. A great quantity of fluid 

 flowed from the wound made by the removal of the winglet, which soon reduced the 

 body to less than one-half of its original diameter. The scales had the same crowded 

 appearance as in Promethea ; their tips had a flattened look, as if they had been 

 pressed upon when growing, which turned them downwards ; those of the fringes on 

 the outer angle appeared as if they might be of their full length. 



When the scales were removed the transverse corrugations were disclosed, show- 

 ing them to be very much finer than those of Promethea, but there was not a trace 

 to be seen of longitudinal foldings, not even on the outer angle ; tha lines of the cor- 

 rugations crossing the wing were quite wavy, which would no doubt admit of a good 

 deal of lateral expansion, but there were no plaits to let out, so I suspect there must 

 be a considerable lateral compression to make up for it, although I could not detect 

 anything in the membrane looking like longitudinal corrugations. 



The winglet dried so rapidly that I made no attempt to lay bare the nervures, 

 but there was no crirapling of the costal edge as in Promethea ; the unexpanded wing 

 being identical in form with the expanded one, which was not the case in Promethea. 

 All going to demonstrate the certainty that we have in this direction abundant scope 

 for investigation, each species probably having something peculiar to itself. 



