690 THE POPULAR SCIENCE MONTHLY. 



ficial circulation was so entirely successful that the veins on the hack 

 of the hand presented a bluish tinge ; a heating like that of the pulse 

 lifted the main artery of the wrist, muscular life revived ; the fingers 

 soon lost their stiffness, and at forty-five minutes after eleven irrita- 

 bility had reappeared in the muscles of the arm ; it was still percepti- 

 ble at four in the morning of the next day. 



Experiment has never more clearly proved that the blood is essen- 

 tial to muscular life. In the limbs of these subjects the organic 

 matter was decomposed, and all vital manifestation had become im- 

 possible. A flow of blood throughout them was effected, and at once 

 this muscular flesh becomes contractile again ; the special activity of 

 the motor fibre is reanimated, and its functions performed as in life. 

 It will, of coux*se, be objected that the muscular element receives its 

 conditions of activity from the motor nerves, and that the blood- 

 globules only vivified it indirectly, by restoring excitability to the 

 nerves ; but has not the mode of action of curare proved that the life 

 of the muscle persisted after the physiological death of the nerve ? If 

 the arteries of the lower limbs of a living animal are tightened by a 

 compress, the withdrawal of the blood will in the same way cause the 

 properties of the nerves to disappear before those of the muscles ; an 

 artificial stimulus, directly applied to the muscular fibre, will still pro- 

 duce movement, after nervous excitability has ceased to exist. If you 

 then remove the compress, you set the flow of the blood free, and the 

 peculiar action of the motor nerves is completely restored. Thus the 

 life of the nervous element itself has been successively extinguished 

 and revived ; after that the inciting stimulus from the train of the 

 spinal marrow may be transmitted through the medium of this con- 

 ductor, which possesses a real autonomy. 



The nerves of general sensation, like the nerves of motion, demand 

 the contact of arterial blood. The anatomical distribution of these 

 nerve-elements does not allow the action of the sanguine fluid upon 

 them to be studied as to their surfaces ; yet sensation constitutes too 

 well-defined a function not to be the object of experimental analysis, 

 as motion is ; this analysis is made by the help of transfusion upon 

 the spinal marrow, the organ that receives all impressions made on 

 the skin. Physiologists have used an ingenious process to prevent 

 the blood from moistening this nervous centre : they inject a liquid 

 filled with an inert powder into the vessels, in a uniform direction ; 

 the capillary parts of the circulation are soon clogged, the spinal mar- 

 row ceases to be in relations with the blood, and ceases at once to 

 receive impressions from the skin. The same phenomenon is observed 

 when all the blood-vessels that go from the main artery of the body 

 to this nervous centre are artificially destroyed ; the return of sensa- 

 tion takes place only when arterial blood is restored to the spinal 

 cord. This fact is also proved by the transfusion of new blood into 

 the veins of an animal that has yielded to a haemorrhage. Again, an- 



