204 E - A - Schäfer, 



often somewhat moniliform before the addition of acid), but eventually 

 they are uniformly swollen. They may, at length, become entirely 

 dissolved. Kölliker states that the intersegmental membranes resist 

 the action of the acid longer than the rest of the sarcostyle, and that 

 they may be seen lying isolated in the preparation. I have not myself 

 been able to observe this. 



The ordinary gold-acid preparations of these muscles are similar 

 to preparations which have been subjected to prolonged treatment by 

 acids, except that the sarcoplasm is stained violet. The muscle-columns 

 have disappeared as such, their spaces in the sarcoplasm alone being 

 left: consequently it is not possible to isolate the columns in these 

 gold preparations. One may, it is true, see in longitudinal view be- 

 tween two strands of sarcoplasm something which looks like a clear 

 muscle column, and the more so because it may appear to be marked 

 transversely at regular intervals by lines of stained substance (Fig. 26). 

 But these lines do not actually lie in the plane of the apparent muscle- 

 column, they are above and below it, and are due to the fact that, 

 the muscle-column having been somewhat constricted opposite the 

 membranes of Krause, it was there encircled by a greater thickness 

 of the sarcoplasm. 



The appearance of alcohol-preparations of these wing-sarcostyles 

 is very striking. It is this which has been described by most observ- 

 ers. The muscles or the entire thorax of the insect may be plunged 

 into alcohol of about 85 — 95 per cent, and examined after a few 

 hours. The columns are easily isolated and they can be stained with 

 liaematoxylin aud many other colouring re-agents. But the method of 

 staining which I have myself found by far the most valuable, giving 

 preparations of the greatest clearness and selectivity, is the alcohol- 

 gold method recommended by Rollett. 



It is not always possible to get the proper result with this 

 method and even in the same preparation there is, as with all gold 

 methods, a good deal of variation in the amount and character of the 

 staining, but these variations are themselves often useful and instruc- 

 tive. For the leg-muscles also, I have found the method of great 

 value and precisely for this variability, as will appear when we are 



