510 EDWARD B. MEIGS 



A COMPARISON OF THE CHANGES OF WEIGHT UNDERGONE BY 



SMOOTH AND STRIATED MUSCLE IN VARIOUS ISOTONIC 



AND NON-ISOTONIC SOLUTIONS 



It will be shown in this section that the changes of weight 

 undergone by smooth muscle in various solutions of electrolytes 

 and non-electrolytes are quite different from those undergone by 

 striated muscle under similar circumstances. The changes of 

 weight undergone by the smooth muscle bear only a rough rela- 

 tion to the osmotic pressure of the solution in which it is immersed, 

 and are such as to make it difficult to beheve that any consider- 

 able portions of the tissue are separated from their surroundings 

 by semi-permeable membranes. But a discussion of the bearing 

 of the results will be reserved until later. 



Experiments with Ringer's solution. Both the smooth and stri- 

 ated muscle of the frogs with which I have worked maintain their 

 irritability, as a rule, for forty-eight hours or more in Ringer's 

 solution at 20°. The sartorii vary somewhat in regard to the 

 changes of weight which they undergo. They sometimes maintain 

 their original weight for many hours, sometimes gain in weight, 

 and sometimes lose. The gain or loss in weight is, however, 

 not often more than 10 per cent of the original weight of the 

 muscle in the course of twenty-four hours, and the Ringer solution 

 may be "considered to be on the average isotonic — that is, about 

 as many sartorii tend to gain as to lose weight in it. 



The stomach muscle of the same frogs practically always gains 

 weight when immersed in Ringer's solution. The amount of 

 this gain is variable being sometimes less than 10 per cent and 

 sometimes over 30 per cent. If the changes of weight undergone 

 by the stomach muscle and sartorius from the same frog be com- 

 pared with each other, it will be found that in those cases where 

 the sartorius tends to lose weight the stomach muscle gains little ; 

 and in those cases where the sartorius gains, the stomach muscle 

 gains much more. In other words, the stomach muscle has a 

 decidedly greater tendency to take up fluid from Ringer's solu- 

 tion than has the sartorius. Figure 1 gives the curves of change 

 in weight of the stomach muscle and sartorius from the same frog 

 in a typical experiment. 



