• PHYSIOLOGY OF SMOOTH AND STRIATED MUSCLE 507 



was never anything to indicate that the smooth "muscle went into 

 rigor either in the neighborhood of the cuts or in any other part. 

 It may even be shown that cross sections of frog's stomach muscle 

 cut off with a sharp razor and only 0.1 to 0.2 mm. thick remain 

 irritable for several hours in Ringer's solution at room tempera- 

 ture. Such slices of muscle may be seen to contract when stimu- 

 lated beneath the microscope after they have been for several 

 hours in Ringer's solution at 20°. 



Other experiments have been carried out with the object of 

 determining the effect which cutting across the fibers of striated 

 and smooth muscle has on the changes of weight undergone by 

 the two tissues in Ringer's solution. It has been found that cut- 

 ting the fibers of striated muscle causes the tissue to gain weight 

 in Ringer's solution. In the case of smooth muscle, the behavior 

 of preparations in which the fibers have been cut across in only 

 one place has been compared with that of others in which several 

 cuts have been made; and it has been found that the latter have, 

 if anything, a slightly less tendency to gain weight than t>he 

 former. 



It is clear, therefore, that cutting across the fibers of smooth 

 muscle has no demonstrable injurious effect on them; and the 

 results of the experiments to be subsequently described will show 

 that the differences in the behavior of striated and smooth muscle 

 cannot be attributed to the fact that the fibers of the latter tissue 

 have been cut across. 



Experiments, in which the changes of weight undergone by 

 muscle in various solutions have been determined, have now been 

 carried out by so many investigators that it is unnecessary to 

 give a detailed defense of the accuracy of such experiments. It is, 

 of course, to be understood that the object is always to follow 

 accurately the change of weight undergone by a piece of tissue, 

 and not to get, at any time, its absolute weight, which is a still 

 undefined quantity. 



Overton states^ ^ that in his experiments on sartorii the limits 

 of error were within 3 mg. In general I have followed the tech- 

 nique which he has described, but I am convinced that the limits 



'^ Overton; Archiv ftir die gesammte Physiologic, 1902, Bd. 92, p. 126. 



