546 EDWARD B. MEIGS 



alkalies than in neutral solutions. Ostwald has found, however, 

 that very small quantities of acid inhibit the tendency of gelatin 

 to absorb water, while larger quantities increase this tendency. 

 In the case of smooth muscle, it may be supposed that the reac- 

 tion of the tissue is normally slightly alkaline, and that the pro- 

 duction of such quantities of acid as can be formed under physio- 

 logical conditions tends only to bring their reaction toward the 

 neutral point. This view is to some extent confirmed by the fact 

 that quantities of acid above 0.025 per cent cause pieces of smooth 

 muscle to take up fluid from Ringer's solution (Experiments 23 

 and 24). 



Such results as those of Experiments 33, 55 and 57, in which 

 it is shown that mechanical stimulation produces a tendency 

 for smooth muscle to shorten and lose weight, receive a ready 

 explanation if it be supposed that the stimulation causes the pro- 

 duction of small amounts of lactic acid. And the same explana- 

 tion may be applied to the results of Experiments 9, 27 and 36 

 in which it is shown that the tissue acquires a tendency to lose 

 weight and shorten after it has been immersed for a considerable 

 period in Ringer's solution. Still further evidence pointing in 

 the same direction is to be obtained from Experiments 16 and 23, 

 in which it is shown that after pieces of smooth muscle have been 

 for some time in a weak acid solution or in Ringer without 

 NaHCOs, stimulation causes them to lengthen, or at least that 

 lengthening is the much more obvious effect of stimulation. It 

 is a very tempting hypothesis that after the reaction of the 

 muscle fibers has been rendered acid the production of still 

 further acid as the result of stimulation causes them to take up 

 fluid and lengthen. 



The results of Experiments 19 and 20 in which it is shown that 

 smooth muscle takes up more fluid from Ringer's solution at 

 higher temperatures, are more or less opposed to these theoretical 

 views. It is difficult to suppose that smooth muscle produces less 

 lactic acid at higher temperatures than at lower ones. But it 

 must be remembered that connective tissue also takes up fluid 

 from Ringer's solution more rapidly at higher temperatures 

 (Experiments 47 and 48) and this indicates that the greater tend- 



