42 H. E. JORDAN 
conclusion is rendered incontrovertible in the light of such 
evidence as is shown in figure 22, where the intersarcostylic 
portion of the telophragma can actually be distinctly seen be- 
cause slightly drawn out of. alignment by reason of a bending of 
the two involved sarcostyles. 
Thulin?® makes a similar claim of non-occurrence for the 
mesophragma. It is more difficult to prove the existence of an 
intersarcostylic portion of this membrane due to its extreme 
delicacy. It may be stated, however, that in the sections 
illustrated by Thulin we would not expect to see the intersar- 
costylic portion of the mesophragma. This membrane, even if 
present, would not be able to withstand the tension exerted by 
the widely separated sarcostyles; and even if sufficiently elastic 
to be able occasionally to maintain an intersarcostylic integrity, 
it would have become too delicate to allow detection by our 
present methods of microscopic examination. That the sarco- 
styles themselves contain mesophragmata as well as telophragmata 
cannot be doubted (figs. 13 and 23). That an intersarcostylic 
telophragma exists is also certain (fig. 22). This membrane is 
intimately attached to the peripheral sercolemma, causing a 
festooning of the latter under certain artificial conditions (fig. 
16). Attachment to nuclear wall may be inferred from ob- 
servations on the muscle of other forms,® but I am unable to 
definitely demonstrate such connection in this muscle. 
Contrary to conditions in the mantis wing muscle,'° for ex- 
ample, where the telophragmata form efficient barriers against 
the longitudinal movement of the sarcosomes, the telophragmata 
of the wasp’s wing muscle must be either fenestrated or have 
become secondarily ruptured and destroyed in certain regions, 
in order to allow for the accumulation of large oval groups (fig. 
21) and compact columns (fig. 23) of sarcosomes. The experi- 
mental evidence from treatment of the sarcostyles with hypo- 
tonic and dehydrating solutions indicates that the intrasarco- 
stylic telophragma is a relatively rigid and but slightly extensible 
membrane. ‘The rigidity of the membrane is indicated by figures 
29, 30, 31, 32, 34, and 35; its slight extensibility by the sharp, 
unbeaded, lateral contour of functionally contracted sarcostyles, 
