22 PRESIDENT’S ADDRESS, 
affect the vitality of the body as a whole. They serve merely as a 
protection, or an ornamental covering, but are otherwise not material 
to our existence. On the other hand, if a few cells, such as those 
nerve-cells under the influence of which respiration is carried on, are 
destroyed or injured, within a minute or two the whole living machine 
comes to a standstill, so that to the bystander the patient is dead; even 
the doctor will pronounce life to be extinct. But this pronouncement 
is correct only in a special sense. What has happened is that, owing 
to the cessation of respiration, the supply of oxygen to the tissues is 
cut off. And since the manifestations of life cease without this supply, 
the animal or patient appears to be dead. If, however, within a short 
period we supply the needed oxygen to the tissues requiring it, all the 
manifestations of life reappear. 
It is only some cells which lose their vitality at the moment of 
so-called ‘ general death.’ Many cells of the body retain their indi- 
vidual life under suitable circumstances long after the rest of the 
body is dead. Notable among these are muscle-cells. McWilliam 
showed that the muscle-cells of the blood-vessels give indications of 
life several days after an animal has been killed. The muscle-cells 
of the heart in mammals have been revived and caused to beat regu- 
larly and strongly many hours after apparent death. In man this 
result has been obtained by Kuliabko as many as eighteen hours after 
life had been pronounced extinct: in animals after days have elapsed. 
Waller has shown that indications of life can be elicited from various 
tissues many 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 weeks 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 obser- 
vation 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 
treatment the limit of which cannot yet be 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 proportions 
(Ringer). Such revival and prolongation of the life of separated 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 circumstances to live, although 
the rest of the body to which they belonged may be dead. 
