2 68 Annals Entomological Society of America [Vol. I^ 



Artemia salina, but I do not believe that even for this species his. 

 evidence is conclusive, and I do not find any satisfactory evidence 

 to overthrow the almost unanimous testimony of careful workers, 

 in favor of the mesodermal origin of this tissue in insects. Sneth- 

 lage objects that the concept of the inpushing of a special, 

 independently originating tissue at definite points in the body- 

 wall savors of the theory of "praestabilierten Harmonie" but 

 this objection would no more hold than in the case of nerve 

 endings, or others that might be cited. Moreover, he overlooks 

 the fact that however the muscle originated, his own objection 

 would still hold when its insertion is considered. 



An important point to be considered in a study of the method 

 of muscle attachment is the remarkable dift'erentiation of the 

 hypodermal cells in the region of the attachment. In many 

 cases as in Anax, they become very greatly elongate and fibrilloid, 

 as compared with the immediately neighboring cells of the body- 

 wall. This is especially clearly seen in figure 5. If the muscles 

 are attached directly to the cuticula, why should there be this 

 great elongation of the epithelium? If, on the other hand, the 

 attachment is through the intermediary of the hypodermal cells, 

 it is just such a change which we might expect. 



Van Rees, '89, found that in the thorax of the pupa of Musca 

 the muscle tendons are developed in this manner, as prolongations 

 of the hypodermal cells which grow inward to meet the devel- 

 oping muscle. Similar studies by Berlese, '01, and by Silvestri, 

 '03, lead them to declare emphatically in favor of the view that 

 the attachment of the muscle is through the intermediary of the 

 hypodermal cells. 



Hecht, '99, has called attention to the remarkable appearance 

 of the muscular insertions in the myrmicophilous dipterous larva,. 

 Microdon. In this form the fibrillated appearance can be traced 

 not only through the hypodermal cells but through the total 

 thickness of the greatly developed secondary cuticula, spreading 

 out fan-like under the primary cuticula. Through the kindness 

 of E. L. Jenne, I have had the opportunity of examining a number 

 of sections of these larvae and find the fibrils very prominently 

 developed but by no means as clearly muscular as Hecht's figures 

 would indicate. A very similar condition is to be found in 

 sections of Muscid larvae, though in the ones which I studied the 

 arrangement of the fibrils was in the form of a cone with its base 

 entad, rather than as in Microdon. In none of the cases were the 



