376 USE OF AETIFICIAL RESPIRATION AND TRANSFUSION. 



the state of rigor mortis by dipping them into warm water. 

 This condition depends on coagulation of the muscular substance 

 or myosin ; and circulation of blood alone through muscles in 

 this state is of no use, for it cannot soften the hardened myosin. 

 Something more is therefore necessary. Coagulated myosin is 

 soluble in a solution of common salt ; bi.t, though a muscle 

 dipped in such a solution may lose its hardness and again 

 become soft and pliable, it does not regain its vitality. By 

 combining the two methods, however, the difficulty has been 

 overcome ; and, by first dipping the rigid muscle in a solution of 

 salt, and then allowing blood to stream through it, Preyer has 

 had the satisfaction of seeing frogs jump and swim by the aid 

 of muscles which had been almost as hard and stiff as a piece of 

 wood only a short while before. 



Nor are nerves and muscles the only parts which can be kept 

 alive by artificial circulation. Glands also preserve their 

 vitality ; and Ludwig and his pupils,"^ by maintaining artificial 

 circulation in them, have succeeded in making livers secrete 

 bile, and lungs excrete carbonic acid, for hours after they have 

 been excised from the body. 



More examples might be given, but the above are sufficient to 

 show the power of artificial circulation to keep any part of the 

 body alive after the death of the rest. The converse of this is 

 also true ; and, if blood be prevented from circulating through 

 any part of the body, that part will die, although the rest may 

 remain healthy. So generally known is this, that no one ever 

 thinks of tying a bandage so tightly as to stop the circulation, 

 and leaving it thus, as he well knows that death, or, as we 

 usually term it, mortification of the ligatured part would be the 

 result. It is easy for any one, indeed, to observe for himself 

 the destructive effects of want of blood and the vivifying power 

 of renewed circulation, by repeating the experiment devised by 

 the Danish physiologist Steno, or Stenson, more than 200 

 years ago. A gentle steady pressure with the tlmmb on the 

 abdominal aorta of a rabbit, so as to stop the circulation for a 

 couple of minutes, is all that is necessary to produce complete 

 paralysis of the hind legs of the animal; and a few minutes 



* Ludwig's Arheiten, 1868, p. 113, and 1870, p. 38. 



