122 P. G. Stiles and C. S. Milliken 



to the freezing-point. By this means we were able to use media 

 which had a uniform osmotic pressure appropriate to the frog's 

 tissues. The value A varied little from o . 50°. 



About thirty experiments of a reasonably consonant character 

 yield data on which the following conclusions are based. The 

 order and duration of the different trials were purposely contrasted 

 as far as possible. Sometimes the immersions were measured in 

 minutes, sometimes in days. When low temperatures were main- 

 tained, it was found possible to keep preparations for nearly a week 

 in extreme instances. 



Skeletal muscles are better preserved by a proper mixture of 

 lithium and magnesium chlorides than by lithium chloride alone. 

 It is naturally difRcult to fix upon the optimum ratio between the 

 two chlorides. Seven parts by volume of lithium-chloride solution 

 to one part of magnesium chloride is a highly favorable propor- 

 tion. If we increase the magnesium much above this fraction, 

 it shows its influence in lowering the irritabihty of the muscle. 



The mixtures favor a maximal performance of work by muscles 

 whether the exposure has been short or long. This is apparently 

 not true unless the stimulation is amply strong, for the irritability 

 of the muscle is probably somewhat depressed in the presence of 

 even a small quantity of magnesium salts. Closely connected 

 with this is the fact that the earlier contractions of the muscle in 

 straight lithium chloride may exceed those of the companion in 

 lithium-magnesium mixture, yet the latter outdoes the former be- 

 cause it outlasts it. This seems to us a very significant fact; per- 

 haps we have here the key to the beneficial working of magnesium. 

 It may be conceived to have the action of economizing the 

 metabohsm, of preventing a wasteful expenditure of substance 

 and energy in the muscle-cells. We have noticed that it lessens 

 contracture in fatigued muscles. This is thoroughly in harmony 

 with the broad statements of Meltzer and Auer, whose work was not 

 known to us when we were first led to these opinions. 



We believe, then, that magnesium in small quantities is a con- 

 serving element in contractile tissue. We may again question 

 whether it is best to designate this action as antitoxic, though there 

 is a marked similarity between our experiments and those upon 



