iSS 



W. L. TOWER. 



the figures is nearly dissolved away the muscles are still attached 

 and a slight contraction of the muscles shown in Fig. 8 would 

 suffice to rupture the cuticula in the median line. And that is 

 exactly what occurs. That is, the rupture of the integument is 

 not due to pressure but to the pull of muscles after the cuticula 

 has become softened. The rupture occurs always in the same 

 place because there is there a weak spot in the cuticula and 

 special provision for the rupture thereof. 



The same sort of structures are found in C. femarata, P. rapes, 

 C. aj/icricana and I suspect in most insects and it is perfectly 

 clear in all of those examined that the rupture of the integument 

 is as described above and in all it occurs at this same place. 



DetacJimcnt of the Muscles. - -The detachment of the muscles 

 does not begin or progress far until after the formation of the 



FIG. 10. C. feinornta. Section of the integument showing the relations of the 

 muscles to the cuticula and the method of the insertion of the muscles. When ecdysis 

 occurs the muscles break from the cuticula along the line AB. 



exuvial suture and is then accomplished by a few violent con- 

 tractions aided no doubt by the corrosion of the tendinous por- 

 tion of the muscle exposed beyond the surface of the hypo- 

 dermis. 



The normal insertion of a muscle in insects to the cuticula is 

 shown in Fig. 10 of C. fciuorata, where the modified tendinous 

 ends are seen to go to the very outer surface of the cuticula. This 



