178 



Scientific Proceedings (67). 



The method employed was essentially that of De Boer, with 

 the exception that the gastrocnemius to be observed was simply 

 severed from its insertion by cutting through the tendo achilles, 

 and then freeing it as far as possible from the underlying muscles 

 by breaking through the intermuscular septum with a probe. By 

 this means the skin remained intact; a desideratum, as it has 

 been claimed that removal of the skin results in loss of tone. 

 The tendon was attached by a thread to a writing lever, and the 

 leg firmly fixed at the knee joint by a muscle clamp. Briefly, the 

 results obtained were as follows: 



When the brain of a frog is pithed, there is a progressive loss 

 of tone in the muscle, due to shock, until a certain maximum 

 lengthening of the muscle is reached in about forty minutes or 

 more. With the recovery from shock, there are usually a number 

 of spontaneous movements, which are registered as contractions 

 of the gastrocnemius, and the muscle after contraction does not 

 lengthen to the same extent as before. One would say it regains 

 a certain amount of tone, but not all by any means. If now the 

 abdomen be opened and the viscera exposed (a necessary proceed- 

 ing for cutting the rami communicantes), there is again a loss of 

 tone. After fifteen to thirty minutes there is again a maximum 

 lengthening of the muscle, and now cutting tne sciatic plexus, or 

 the rami communicantes has no effect, except that the contraction 

 which results from cutting the sciatic is not followed by a "con- 

 traction remainder" as was the case after spontaneous contractions 

 with the nervous connections intact. 



It seems possible then, that the results obtained by De Boer 

 were due to the effects of the operation rather than to the cutting 

 of the rami communicantes, for it appears from his article that he 

 began his observations at once. It seems clear also that for the 

 present we shall have to hold fast to our old idea that tonus of 

 skeletal muscle is dependent upon the central nervous system, and 

 not on the sympathetic. 



