508 EDWARD B. MEIGS 



of error in my experiments with sartorii are less than those which 

 he gives, perhaps within 1 mg. The chief source of error is, of 

 course, the drying of the tissue on filter paper which is necessary 

 before weighing; unless the tissue is dried to the same extent each 

 time, the results do not truly represent the course of gain or loss 

 of weight. After a certain amount of practice one learns to 

 keep to a very uniform routine in the matter of drying, and to 

 recognize immediately the errors which sometimes occur when 

 one is fatigued. Experiments in which errors have occurred 

 must of course be discarded. I may say, however, that I have 

 been obliged to discard only very few experiments on this account; 

 the general character and smoothness of the curves of striated 

 muscle are sufficient evidence for the view that the errors in weigh- 

 ing have been small. 



In the case of the smooth muscle the drying is not quite so 

 easy as with the striated muscle, for the sheets of tissue often 

 exhibit a considerable tendency to curl' up. One soon learns, 

 however, to flatten them out on the filter paper in a uniform man- 

 ner; the limits of error here are certainly within 2 mg. 



The irritability of the tissues was tested by means of a strong 

 interrupted Faradic current. I determined whether the stri- 

 ated muscle responded to the stimulus or not by direct inspec- 

 tion. In the case of the smooth muscle, strips of the tissue were 

 attached to a fight lever which magnified about seven times and 

 the point of this was brought against a scale. In this way very 

 slight changes in length could be determined. A considerable 

 amount of experience with the effects of various kinds of stimuli 

 on smooth muscle has convinced me that a strong rapidly inter- 

 rupted Faradic current is by far the most satisfactory, if one 

 merely wishes to determine in a rough way the state of the tissue's 

 irritabifity. I have never failed with this stimulus to produce 

 responses in fresh tissue, and the responses are fairly constant in 

 size and rapidity. I have, of course, been careful to keep my 

 current far below the strength which would produce heat shorten- 

 ing in dead tissue. 



In the case of striated muscle the irritability of the actual mus- 

 cle weighed was determined. This could be done with almost no 

 manipulation of the muscle; and as the application of the current 



