Dr. Alexis Carrel, who has kept a piece of chicken heart growing for 19 years, last week announced his verdict against rejuvenation. Biologists know a great deal now, he wrote, about how people grow old. They probably will learn what is necessary to retard the aging process. But it will be impossible, he declared, to reverse the action.
Life rushes into existence. The child lives much more in a year than do his parents. Dr. Carrel mentioned tests which give precise indications of an individual's biological (not chronological) age. If a spickle of flesh is put in a certain kind of culture medium, the spickle will grow for a time. The time and speed of growth indicate the "residual energy" of that bit of flesh. The younger the individual, the faster and longer the growth. A similar test is how long a wound takes to heal. Young people heal more quickly than old. Dr. Pierre Le Comte du Noüy of the Paris Pasteur Institute, one-time Rockefeller Institute colleague of Dr. Carrel, has worked out age tables for wound healing. The reason that the young heal and grow more quickly than the old is that as soon as one begins to live, he begins to kill himself. All living cells give off waste products which, unless removed, clog continued growth. The older a person is. the greater the clogging. If it were possible to replace all of a person's old and decrepit cells by young ones, and if it were possible to cleanse every drop of blood, lymph and other liquid in his body, then he would be rejuvenated. How to accomplish all that has, said Dr. Carrel last week, "still to be discovered. . . . No senescent organism has ever been rejuvenated by the procedures of Steinach* and Voronoff. . . .† The process of aging remains irreversible."
*Making the gonads practically ductless by partly disabling them (TIME, Sept. 30, 1929 et ante). †Supplanting the testes by the testes of other men or animals (TIME, Sept. 15. 1930 et ante).