80 THE REPORT OF THE [19 



It would be profitless to relate the difficulties I had to encounter in the prosecution 

 of my investigations ; and how I had to gain my information for success through failures 

 in my efforts to accomplish the object in view ; but it may be of use to anyone who 

 wants to prosecute the enquiry to know what I earned during the process. 



For the examination of an unexpanded wing, the chrysalid should be allowed to 

 mature as nearly as possible to the point of emerging before it is killed, which I did by 

 placing it in alcohol ; then it is the better to hang for twelve hours for some of the mois- 

 ture to evaporate. For the comfortable handling of an expanded wing, after full deve- 

 lopment it should be allowed to obtain complete firmness, which may take an hour or two, 

 before killing the insect and separating the wing from the thorax. The only place that I 

 could find an entrance for a pin point between the membranes, was at the base of the 

 wing, where the subcostal and median veins come close together ; when once the pin has 

 entered, either in a vein or between the two, it can be moved back and forth through 

 the entire width of the wing without encountering the slightest obstruction. The upper 

 and under membranes of the wings are at the front and hind edges all in one piece, 

 and must be cut to get them apart, which can be done by running the pin down through 

 them, and so delicate are they, that this can be done without feeling tbat any extra pres- 

 sure is required. Because of that extreme tenderness I had some difficulty in obtaining 

 conclusive evidence as to the actual structure of the outer angle of the wings, until I be- 

 thought me of getting water between the membranes. With great care, after many 

 trials, I succeeded in inseiting a fine glass tube at the base of a wing, and soon had 

 water flowing into it. Resting the wing on the surface of a tumbler of water, it soon 

 rounded out like a bladder ; but as soon as the water touched the outer angle the b'adder 

 collapsed, all the water having gone together, and the membranes were as before it en- 

 tered. This sac will not hold water, the membranes being finished and fringed indepen- 

 dently of each other at the outer angles. 



The greatest difficulty in getting the membranes separated, and in getting them to 

 stay apart arises from the gummy nature of the fluid that has entered between them 

 from the thorax. If one separates a part of the wing and lets it go again, the sides are 

 instantly as closely united as they were at first : or if a portion of the membrane folds 

 in upon itself, one is far more likely to tear it than turn it back, in their efforts to 

 straighten it. My available material had become reduced to three chrysalids, and I had 

 not then obtained a perfect example, and was beginning to wonder if the effort was to 

 prove a complete failure, when I thought of trying to separate them under water, and 

 found it to work admirably. I could then separate the membranes without difficulty or 

 danger ; when separated I floated each half on to a bit of oiled paper, transferred them 

 to blotting paper with their outsides next to it, then allowed some of the superfluous 

 moisture to evaporate before covering them and putting them under pressure to thor- 

 oughly dry, when they came out in perfect condition. , 



The fluid which had been stored up in the thorax of the pupa flows in between 

 the membranes of the wings at the opening by the subcostal and median veins, passing 

 along and expanding them as it goes until the wings have attained their full dimen- 

 sions ; the fluid as it dries becomes more gummy and adhesive, and when perfectly dry 

 the butterfly's wing with which we are all familiar is completed. The veins and nervures 

 are situated half in one membrane and half in the other, the heaviest portion being in 

 the upper membrane and open in the centre ; so there is every reason to believe that the 

 fluid does pass into, and through between them as it does between the membranes, but 

 when it dries it forms such a thin coating on their inner sides that it practically leaves 

 them empty. Then when the fluid has quite dried it has cemented the two halves to- 

 gether, which form the hollow tube that has been the subject of so much discussion ; 

 whilst at the same time it tends to stiffen and strengthen them as it does the membrane. 

 Here I have the opportunity of correcting myself in a statement I made of what I 

 thought I saw in an unexpanded wing. Twenty fifth Annual Report of the Entomolo- 

 gical Society of Ontario, page 65, where I state that " The nervures are in the upper 

 membrane, with a groove in the lower opposite, into which they fit." That appearance I 

 found frequently produced, by the walls of the larger veins in the upper membrane clos 



