on the Metamorphosis of Caterpillars. 159 



length to reach from one spiracle to another, it occasioned the 

 appearance of what I at first took for a continuous band as above 

 mentioned. On reflection it at once appeared to me that these 

 must be the exuvia of the trachice, which, as described by Swam- 

 merdam, " being collected into eighteen thicker and as it were 

 compounded ropes, nine on each side of the body, when the skin 

 is cast, slip gently and by degrees through the eighteen apertures 

 in orifices of the pulmonary tubes before described, having their 

 tops directed upwards towards the head."* To ascertain this 

 beyond a doubt, I gently moved one of the portions of the band 

 above mentioned about in water, when I had the satisfaction of 

 seeing it immediately separate into those minute filaments, which 

 proved the exact correspondence of my observation with Swam- 

 merdam's statement. It was so late in the season when my atten- 

 tion was drawn to this subject, that I had no opportunity of ex- 

 amining the moults previous to the change into the pupa, but I 

 entertain no doubt that precisely the same operation is undergone 

 in the former moults, and that because Swam.merdam states such 

 to be the case, whose testimony on this head has never been im- 

 pugned but by Herold, whose statement I trust I have abundantly 

 shown to be quite unfounded. 



I must not omit to mention that the correctness of Swammer- 

 dam is likewise confirmed by Burmeister, inasmuch as he relates -{■ 

 that he had himself witnessed the facts described in the moulting 

 of the Libellulce, from all which circumstances it is apparent, that 

 this internal moult, as described by Swammerdam, is universal 

 throughout the class of insects, being thus shown to exist in the 

 Coleoptera by Swammerdam, in the Neuroptera by Burmeister, 

 and in the Lepidoptera partly by Bonnet and more fully in the 

 present paper. How so eminent a man as Herold could fall into 

 such an unfounded delusion as regards this matter, and in defiance 

 too of the express declarations of such an accurate observer as 

 Swammerdam, is a mystery. For myself, I have had no object 

 in bringing forward the subject except to confirm the truth, 

 careless as to whose reputation might be confirmed or affected 

 thereby. 



* Biblia Naturae (Hill's Eng. Translation), vol. i. p. 135. 

 t Shuckard's Translation, p. 428. 



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