STRIPED MUSCLE OF WASP 35 
tion in 10 per cent formalin also produces a slight shrinkage, 
and in lightly stained sections reveals the mesophragma very 
clearly (fig. 28). The sareostyle bulges slightly at the levels of 
the telophragma, as if held open by a structure capable of resist- 
ing the shrinkage effected at the level of the mesophragma. ‘The 
telophragma is evidently a relatively robust and relatively non- 
elastic structure. 
Figure 29 illustrates a sarcostyle after immersion for a brief 
period in distilled water. The sarcostyle is distinctly swollen 
and beaded; the constrictions are at the levels of the telophrag- 
mata, indicating again the relative inextensibility of these 
membranes. The dark disc lies in the middle of the ‘bead,’ and 
appears shorter than in the sarcostyle observed in Ringer’s 
solution. This sarcostyle has been altered through imbibition 
of water. The beading is the result of endosmosis. The thin- 
ning: of the dark disc is compensatory to its increase in width 
following the lateral extension of the sarcomere. After some 
hours in distilled water the sarcostyle swells to several times its 
normal size, the dark substance becomes diffused throughout 
the fibril, and finally the sarcomeres may rupture and the sarco- 
plasm escape. 
Treatment according to Rollet’s technic yields results similar 
to those with distilled water, except that the telophragma and 
the dark disc are stained purple with the gold chlorid. Figure 30 
represents a separate sarcostyle imperfectly stained in a prepa- 
ration by Rollet’s gold-chlorid method. Figure 31 represents a 
successfully stained sarcostyle. The Q-dise was stained lightly 
purple. This illustration corresponds with Schaefer’s: sarcostyle 
A, figure 6, which the latter interprets as a contracted fiber. 
But it corresponds also with figure 29, and in fact shows the result 
of the action of a hypotonic solution. It is not a contracted 
fiber, but a swollen relaxed fiber. Figure 32 illustrates a later 
stage in this same endosmotic process with Rollet’s technic, 
and shows a greater degree of swelling with a diffusion of the 
deeper staining substance throughout the sarcostyle. 
To return to figure 31, it may first be noted that the beaded 
condition in this degree appears generally only in isolated sarco- 
