OLD AGE, 589 



during embryonic life that cells are produced with the greatest 

 activity. Later on this proliferation becomes slower but it neverthe- 

 less continues to occur throughout the course of life. Biihler attrib- 

 utes the difficulty with which wounds heal in the aged, precisely to 

 the insufficiency of cellular production. lie also thinks that the 

 reproduction of the cells of the epidermis Avhich are to replace the 

 desiccated parts of the skin diminishes notably during old age. 

 According to this author it is theoi-etically easy to predict the 

 moment when cullular multiplication in the epidermis nnist com- 

 ])letely cease; as the desiccation and desquamation of the superficial 

 parts continues without cessation it l)ecomes evident that it must 

 finally result in the total disappearance of the ejiidermis. The same 

 rule is applicable, according to Biihler to the genital glands, the 

 muscles, and all sorts of other organs. 



These theoretical considerations do not, however, agree with well- 

 known facts which speak l)ut little in favor of a general diminution 

 of cellular proliferation in old age. The hairs and the nails, which 

 are excrescences of the epidermis, keep on growing throughout the 

 entire life, thanks to the reproduction of the cells which constitute 

 them. There is no arrest at all in the development of these parts 

 even in the most advanced age. Far from that. We know that the 

 hair that covers certain portions of the body increases in quantity 

 and length in the old. In certain inferior races like the Mongols, 

 the mustaches and the beard do not grow abundantly until advanced 

 life, while young people have but small mustaches and very little 

 or no beard. In women of the white race the same phenomenon 

 occurs. The delicate and almost imperceptible down that covers the 

 upper lip, the chin, and the cheeks of young women is transformed 

 into veritable hair which forms the nuistaches, beard, and whiskers 

 of old women. Doctor Pohl, a specialist in everything that concerns 

 the hair, measured the rapidity of growth of hair under different 

 circumstances. He found that in an old man of 01 years the hairs of 

 the temples grew 11 nun. in a month. But these hairs, in the 

 same regions, in boys of from 11 to 15 years grew in the same time 

 11.8 nun., which represents almost the same figure. 



There is therefore in the three subjects studied by Doctor Bold no 

 considerable diminution in the cellular growth in the old, in spite 

 of the great difference in age. It is true that this observer showed 

 that the hair of a young man between 21 and 24 grew at a rate of 15 

 mm, per month, while in the same individual at the age of 01 

 years the rate lowered to 11 mm.; but this slowing down of the 

 growth of the hair was only apparent. In fact, the first figures 

 related to hair from different regions of the hairy scalp, while the 

 second related only to the hair of the temples. Now it is well estab- 

 lished by Doctor Pohl himself that in the latter place the hair grows 



