266 An 1 1 a Is E ntom ologica I Society of A merica [ Vol . I , 



membrane, being soldered to the ceil-, as in C, of the text-figure. 

 Or, as in D, the union might be due to the interlacing or dove- 

 tailing of the muscle fibrils with those of the hypodermal cells. 



Apparently clear illustrations of the direct passage of the 

 muscle fibrils through the hypodermis are afforded by sections 

 of the nymph of Chortophaga viridifasciata, an Acridid. vSuch 

 a section is represented in the photomicrograph, plate XXIV, fig. i , 

 and from the study of such sections alone there would be little 

 question that the muscle fibrils are attached directly to the 

 cuticula. Unless they have themselves become fibrinoid there 

 is left at the point of muscle attachment but little trace of the 

 hypodermal cells. They are clearly indicated by their nuclei, 

 which are larger than those of the muscle and in which the 

 distribution of the chromatin is also different. Moreover, their 

 limits are shown by the very definite, dark-brown pigment 

 granules similar to those found in the hypodermal cells of other 

 regions. 



Snethlage has pointed out that it is easy to see how^ an 

 oblique section through the muscle and the overlying hypodermis 

 would present, in some cases, the appearance shown in C, and 

 thus lead to a misinterpretation. On the other hand, if an axial 

 section presents the appearance shown in the photograph, it 

 becomes a question of determining whether the prominent fibrils 

 in the hypodermal cells are muscle fibrils, pushing through the 

 cell as in B, or whether they are what Maziarski, '03, has aptly 

 denominated tonomitomes, i. e., filaments of protoplasm differ- 

 entiated in the epithelial cell itself, as a result of mechanical 

 stimulus. 



It was when examining some sections of the nymph of Anax, 

 prepared by Dr. Needham for the study of wing development, 

 that I had my attention attracted to striking evidence in favor of 

 the view that muscle attachment in insects is through the inter- 

 mediary of the hypodermal cells, as has been maintained by 

 Weismann, '63, Leydig, '85, Bertkau, '85, Duboscq, '98, and 

 others. 



As may be seen from figure 2, the hypodermal cells in the 

 region of the muscle attachment are very elongate and narrow, 

 measuring about 5o/( in length and 5/i in width. They are 

 sharply differentiated by the haematoxylin-eosin stain, being 

 much bluer than the attached muscles. Their nuclei are also 

 distinct from those of the muscle fibers. The cells are feebly 



