SENESCENCE, DECADENCE, AND DEATH 419 



situations, such as between the bodies of the vertebrae 

 and about the intervertebral discs, so that individual 

 vertebrae become welded together and immovably 

 fixed. If the muscles of the erector spinae group have 

 permitted the body to drop forward, the spine may 

 become hopelessly fixed in this curved position. It is 

 partly through such bony changes that the height of 

 the aged person becomes considerably reduced. 



The skin and its appendages show well-marked atrophic 

 changes. The first of which may be whitening of the 

 hair. This has been found by Metchnikorf to depend 

 upon the absorption of the pigment from the cells of the 

 medulla of the hair by phagocytic cells pigmentophages 

 through whose activity it is first transferred to the 

 bulb of the hair, and subsequently removed altogether* 

 With or without the loss of the color, the hair follicles 

 may atrophy and baldness occur. Though such changes 

 occur upon the scalp and beard and about the pubes 

 and axilla, the hairs of the beard and eyebrows are apt 

 to become coarse and bushy, and coarse hairs frequently 

 appear upon the ears and elsewhere. The skin itself 

 becomes thinned, shining, more or less transparent, 

 and marked with brownish discolorations. The sense of 

 touch is impaired, so that it is probable that the sensory 

 end organs of the nerves also atrophy and disappear in 

 part. 



The sexual organs participate in the ^senile changes, 

 those of women more early than those of men. With 

 women the first change is physiological and is shown by 

 the cessation of menstruation menopause. This is 

 soon followed by atrophy and cirrhosis of the ovaries, 

 more or less atrophy of the uterus, and involution or 

 atrophy of the mammary glands in which the glandular 

 tissue is in part replaced by adipose tissue. 



In men the atrophic changes of the sexual organs is 

 postponed for a considerable time, so that the sexual 

 life of a man is considerably longer than that of a woman. 

 Eventually, however, the testes show atrophy and pig- 



