APPLICATIONS AND POSSIBILITIES 259 



serve them in the elderly as they do in youth is a problem to 

 be solved when we understand the laws of regeneration, at present 

 almost totally beyond our control. Some say that it is a matter 

 of the wear and tear of our blood vessels, those rubber-like tubes 

 which transport food and drainage with nonchalant equanimity 

 to all cells as long as they last. In the classic phrase: a man 

 is as old as his arteries, ergo his ductless glands will be as old 

 as their arteries. And the age of arteries is simply a matter of 

 wear and tear, the resultant of the function which is universal 

 among molecules. Arteriosclerosis, the hardening of arteries, 

 might be the whole story. 



But there are certain experiments and considerations which 

 rather confute that easy explanation, or at least make clear that 

 the mystery is not so simple. The work of Steinach, a Viennese 

 investigator, has contributed most to the elucidation of the non- 

 arterial factor in senility. No one has asserted more loudly the 

 importance of the interstitial cells that fill in the spaces between 

 the tubules of the testes in the male, and the follicles of the ovary 

 in females. Rats have been his medium of study, for they are 

 most easily procurable, live fastest, breed, and withstand experi- 

 mental and operative procedures better than any other animal. 



An old rat is like an old man in his dotage. His bald, shriv- 

 elled skin covers an emaciated body. His eyes are dimmed by 

 cataracts and his breathing is labored and difficult because his 

 heart muscle has lost its tone. Huddled in a corner, life to him 

 has become concentrated into the desire for a little food, and 

 immobility. If now, something is done to his sex apparatus, a 

 marvelous transformation may be effected. That something no 

 one could predict. It consists in slitting the genital duct, which 

 leads from the germinal cells to the exterior. After the operation, 

 the germinal cells, which grow into the spermatozoa, atrophy and 

 disappear, since they can no longer function. As if released from 

 some restraint, the interstitial cells, however, multiply enor- 

 mously. With their multiplication, the miracle of rejuvenation 

 is performed. 



After some weeks the sluggish currents of being in the rat, 

 which had slowed down as a preliminary to stopping altogether, 

 flow fast and furious. Waves of new chemical substances inun- 

 date his cells. And they respond like the fields that border the 

 Nile after the annual flood. All his tissues, skin, muscle, nerve, 

 even bone, are restored. A vitality is created which makes him 

 bound and dart like a youth of his species. In due time, though, 



