33 



composed are, in the unexpanded state, corrugated into a vast number of folds, transverse 

 as well as longitudinal, and that the nervures are folded. Are any of our readers mic- 

 roscopists'? If so, will they try and verify this statement." After reading that, and 

 considering the matter, it occurred to me that I might be somevvhat fortunately situated 

 for making an attempt at discovering the facts of the case. First, because I was in 

 possession of a number of the cocoons of large Boiiliycids which had failed to produce 

 moths, therefore some of them might be found to be good subjects for investigation. 

 And secondly, although not a microscopist myself, I wa.s sure I could obtain the able and 

 willing services of some members of our Microscopical Section : so I examined my cocoons. 

 I had four Samia Cynthia, out of nine which I had received from Mr. James Angus, of 

 New York. In three of them the caterpillars had failed to transform, the fourth con- 

 tained a pupa. 1 had also two promethea. In one was the pupa of a large female, but so 

 ?oft that it would not endure handling ; in the other I found a small male, dry and firm. 

 I called the attention of Mr. Foot, one of the younger members of the section to the 

 subject and read to him Dr. Buckell's request ; he at once responded with, " Let us try." 

 I should state here that the investigation extended over sev^eral weeks. My method was 

 to take notes of what I saw, or thought I saw, at any time during its progress, compare 

 and correct them afterwards, and if there was conflict or uncertainty, I had further views 

 to verify. But before entering into details I will quote more extensively from Kirbv 

 and Spence. In vol. 3 p. 293, we read, " To understand more fully the cause of this rapid 

 expansion and development of the wings, though often exceedingly thin, they are always 

 composed of two membranes, having most commonly a number of hollow vessels running 

 between them. These tubes, which after the French entomologists, I would name ner- 

 vures, contribute as well to the development of the wiags as to their subsequent tension. 

 In the pupa, and commonly afterwards, the two membranes composing the organs m 

 question do not touch each other's inner surface, as they afterwards do ; and being moist 

 and corrugated into a vast number of folds like those of a fan, but transverse as well as 

 longitudinal, and so minute as to be imperceptible to the naked eye. the wings appear 

 much thicker than in the end. Now, as soon as the insect is disclosed, a fluid enters the 

 tubes, and being impelled into their minutest ramifications, necessarily expands their folds; 

 for the nervures themselves are folded, and as they gradually extend in length the moist 

 membranes attached to them are also unfolded and extended. In proportion as this 

 takes place, the expanding membranes approach each other, and at last, being dried by 

 the action of the atmosphere, become one." This description seems to be taken from 

 observations made of butterflies, which will doubtless differ in some respects from moths. 

 We commenced operations by trying the Cynthia first. The wing-case was thick and 

 hard ; when broken and removed the winglet was disclosed lying close to the shrunken 

 body, smooth and transparent as that of a fly ; not the vestige of a scale visible, nor an 

 indication of where they were to come from. Under the glass it was a most interesting 

 object, but worthless for our purpose. The question forces itself on our attention here, 

 At what stage of the pupal period does the scale begin to grow 1 



We next took up the Promethea, which proved to be in tine condition for the .in- 

 vestigation. The wing cover came off freely and clean, disclosing the winglet scaled and 

 coloured and apparently ready for emerging ; when it was removed, it measured just over 

 three-eighths of an inch from joint to apex, and one-fourth of an inch across the widest 

 part ; which possibly might have expanded to one and a half or two inches. 



The first survey of it through the glass at once suggested compression, lateral and 

 longitudinal, the minute scales were so crowded on one another that they almost stood 

 erect, yet the ornamentation was distinct. When the scales were removed the transverse 

 corrugations were disclosed, crossing the wingletat quite irregular angles, but the term "fold- 

 ings," applied to them would convey an erroneous impression; drawings or gatherings would 

 be more correct. They had an exact resemblance to some gatherings in ladies' dressmaking. 

 The front edge had a singularly knotted appearance which I could make nothing of at the 

 time. 



Longitudinally, the foldings were unmistakable, but with nothing like the regular- 

 ity of a fan ; they were of quite unequal length and depth ; some were but a slight de- 



3 (EN.) 



