82 OF VITAL MOTION. 



The connexion of the state of contraction 

 with the direct operation of external cold may be 

 illustrated by two familiar facts, which facts also are 

 well calculated to show one cause at least why cold 

 does not always produce this result. In the process 

 of crimping^ for example, the fisherman produces the 

 contraction which imparts the requisite firmness to 

 the flesh, by first gashing the sides of a fish with a 

 knife, and then dashing them with cold water. In 

 cases of amputation, also, where the blood oozes obsti- 

 nately from the stump, the surgeon causes contraction 

 in the muscles and vessels (and in this way arrests 

 the haemorrhage) by the application of a sponge 

 soaked in cold water. In both these cases the con- 

 traction is attended with the escape of blood from the 

 vessels, and hence we may find a reason, perhaps, why 

 contraction is not induced when the free movements 

 of the blood are interfered with, whether by coagula- 

 tion, by removal from the sphere of the circulation, or 

 by any other means. We may conjecture further, 

 that free mobility of the blood is necessary to mus- 

 cular action, in the same way that it is to the changes 

 which take place in erectile tissue, and that the filling 

 or emptying of the vessels is as necessary in the one 

 case as in the other. In other words, we may con- 

 jecture that the causes of muscular action operate 

 upon the fibrous coats of the vessels, as well as upon 

 the other fibrous textures. 



