MUSCLE ATTACHMENT IN INSECTS.* 



William A. Rilky. 



As a rule, writers on insect histology have been content to 

 state that the muscles are attached to the body-wall, without 

 attempting to explain the mode of attachment. Within the 

 past few years considerable attention has been paid to this phase 

 of the subject, but there is little agreement in the views expressed 

 and the question can by no means be regarded as closed. For 

 some time, in connection with general work, the writer has paid 

 special attention to this question, intending to make a study of 

 the conditions in a wide series of insects. The comprehensive 

 work of Snethlage, '05, and his exhaustive review of the litera- 

 ture, have rendered superfluous extended publication of these 

 results but it is desired to call attention here to some features of 

 the subject which have not been emphasized, and especially to 

 the striking conditions to be found in the nymphs of Anax, a 

 dragon-fly. 



Theoretically, considering the structure of the body-wall of 

 an arthropod, the muscles may be attached in any one of the 

 several different ways. The fibers may be fastened directly to 

 the cuticula or they may be attached through the intermediary 

 of the hypodermal cells. 



In the first instance, either the muscle fibers would force 

 their way between the hypodermal cells in order to reach the 

 cuticula (text-figure ,4), or their fibrils would pass directly 

 through the hypodermal cell-body, (text-figure B). 



Fig. G. Diagrams showing four possible methods of attachment of muscle 

 fibers in arthropods. For explanation see text. ' 



In case the attachment be through the intermediary of the 

 hypodermal cells, the fibers might abut against the basement 



* Contribution from the Entomological Laboratory of Cornell University. 



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