MUSCLES. 287 



ture after being equally scored with a knife. The specific gra- 

 vity of the crimped fish was 1*105, that of the dead fish, after a?, 

 equal immersion in water, 1*090. 



A piece of cod-fish, weighing twelve pounds, gained in weight 

 by crimping two ounces avoirdupois, or rather more than one per 

 cent. ; and another less vivacious piece of fifteen pounds gained 

 one ounce and a-half. The hinder limb of a frog having the skin 

 stripped off, and weighing 77*1 grains, was immersed in water 

 of 54, and suffered to remain nineteen hours. It became rigid, 

 and weighed 100*25 grains. So that the increase of weight amount- 

 ed to 30 per cent., while at the same time the specific gravity had 

 increased, as in the case of the crimped fish. 630 grains of the 

 subscapularis muscle of a calf, which had been killed two days 

 from the 1 Oth of January, were immersed in hard- water at 45. 

 In ninety minutes the muscle was contracted, and weighed 770 

 grains. So that the increase of weight was rather more than 

 22 per cent. ; while, at the same time, the specific gravity of the 

 muscle had increased.* 



Many attempts have been made to give a theory of muscular 

 motion ; but hitherto little satisfactory information on this intri- 

 cate subject has been suggested. One of the latest and most 

 ingenious theories on the subject is that of Prevost and Dumas. 

 According to them, the nervous filaments enter the muscles at 

 right angles, and, a'fter having traversed the muscular fibres turn 

 back and cross the same fibres in a direction parallel to their ori- 

 ginal one. A current of electricity passes through these nerves. 

 It moves in one direction in the first portion, and in the oppo- 

 site direction in the recurrent nerves. Hence the currents at- 

 tract each other, the muscular fibres are shortened, and muscular 

 motion produced. Before examining this theory, it would be ne- 

 cessary to establish by accurate anatomical dissections that the 

 direction of the nerves is as these philosophers allege. 



* Carlisle, Phil. Trans. 1805, p. 23. 



