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some peculiarity, that led me, some years ago, to question 

 you so closely relative to the moulting of the Cecidomyians. 

 According to my present views, the point of time when "the 

 insect may be said to enter on the pupa state ' : is the mo- 

 ment when the limbs of the future fly become visible ; this 

 occurs only a very few days before the evolution of the fly, as 

 I have myself witnessed. Previously to that moment the insect 

 appears in the form of a larva, a mere maggot, without a vestige 

 of wings, antenna? or legs. The conversion of the insect from 

 this form to that wherein the wings, antenna?, and the legs are 

 visible, is effected (by the growth of these parts) without a 

 casting off of the skin, as before stated. The Hessian Fly is 

 said by some to undergo a coarctate transformation, or rather to 

 have a coarctate pupa. This is true in one sense, but not in the 

 sense commonly so understood by entomologists. It was this 

 very difference that so much puzzled me years ago. All this 

 time you were fully aware of it ; but owing to our not making 

 use of the same phraseology, you failed to communicate your 

 discoveries to me fully. It was only after I had examined the 

 puparium of the Hessian Fly, and the included pupa, and had 

 compared the latter with the (mature) pupa of other species, and 

 had witnessed how the latter came into this state, that I saw 

 through the whole matter, and then discovered from various 

 passages in your writings, that you had seen the same long ago. 

 I have been anxious to give you full credit for every item of in- 

 formation derived from you and contained in my work. At the 

 risk of being tedious, I have here taken some pains to make my- 

 self understood now, and have had to write amidst various inter- 

 ruptions. My object is not to controvert what you may have 

 stated as to the time when the Hessian Fly " may be said to 

 enter the pupa state," but to show that I understood that there is 

 a period, a long period, during which the insect included within 

 the flaxseed shell has the form of a larva and " lies a motionless 

 grub " as you have stated. Dr. Fitch calls the insect, during 

 this period, a dormant larva ; perhaps you would call it an 



