512 ANNUAL EEPORT SMITHSONIAN INSTITUTION, 1912. 



hours and even days after general death. Sherrington observed the 

 white corpuscles of the blood to be active when kept in a suitable 

 nutrient fluid weelvs after removal from the blood vessels. A French 

 histologist, Jolly, has found that the white corpuscles of the frog, if 

 kept in a cool place and under suitable conditions, show at the end of 

 a year all the ordinary manifestations of life. Carrell and Burrows 

 have observed activity and growth to continue for long periods in the 

 isolated cells of a number of tissues and organs kept under observation 

 in a suitable medium. Carrell has succeeded in substituting entire 

 organs obtained after death from one animal for those of another of 

 the same species, and has thereby opened up a field of surgical treat- 

 ment the limits of which can not yet he descried. It is a well- 

 established fact that any part of the body can be maintained alive 

 for hours isolated from the rest if perfused with serum (Kronecker, 

 frog heart), or with an oxygenated solution of salts in certain pro- 

 portions (Ringer). wSuch revival and prolongation of the life of sep- 

 arated organs is an ordinary procedure in laboratories of physiology. 

 Like all the other instances enumerated, it is based on the fact that 

 the individual cells of an organ have a life of their own which is 

 largely independent, so that they will continue in suitable chcum- 

 stances to live, although the rest of the body to which they belonged 

 may be dead. 



But some cells, and the organs which are formed of them, are more 

 necessary to maintain the life of the aggi-egate than others, on account 

 of the nature of the functions which have become specialized in them. 

 This is the case with the nerve cells of the respiratory center, since 

 they preside over the movements which are necessary to effect oxy- 

 genation of the blood. It is also true for the cells which compose the 

 heart, since this serves to pump oxygenated blood to all other cells 

 of the body; without such blood most cells soon cease to live. Hence 

 we examine respiration and heart to determine if life is present; 

 when one or both of these are at a standstill we know that life can not 

 be maintained. These are not the only organs necessary for the 

 maintenance of life, but the loss of others can be borne longer, since 

 the functions which they subserve, although useful or even essential 

 to the organism, can be dispensed with for a time. The life of some 

 cells is therefore more, of others less, necessary for maintaining the 

 life of the rest. On the other hand, the cells composing certain organs 

 have in the course of evolution ceased to be necessary, and their con- 

 tinued existence may even be harmful. Wiedersheim has enumer- 

 ated more than a hundred of these organs in the human body. Doubt- 

 less nature is doing her best to get rid of them for us, and our descend- 

 ants wiU some day have ceased to possess a vermiform appendix or a 

 pharyngeal tonsil; until that epoch arrives we must rely for their 

 removal on the more rapid methods of surgery. 



