ATROPHY OF THE SKIN. 449 



sons. Not unfrequently, however, this calvities occurs in younger per- 

 sons ; hereditary predisposition apparently being one of the most com- 

 mon of its causes. No reliance is to be placed upon the statement of 

 Daldness's having arisen from over-exertion of the brain, over-anxiety, 

 or from sexual excess. There is a very large number of profoundly- 

 learned persons, as well as careworn and dissipated people, whose hair 

 grows luxuriantly ; while many others, who think but little, and live con- 

 tinently and unoppressed by care, lose then* hair early in life. Of course, 

 there is no means of producing a development of new hair-bulbs; 

 hence, in spite of the pretensions of charlatans, this form of baldness 

 is incurable. This is not the case with the deflumum capillorum, or 

 falling out of the hair, which occurs during and after certain acute and 

 chronic diseases, during which the hair-follicles suffer temporary de- 

 rangement of nutrition. Here the follicle is not destroyed, nor is it 

 even permanently injured. When the disease causing the loss of the hair 

 has subsided, and when its effects upon the general constitution have 

 disappeared, the hair-follicles are restored to health, and reproduce 

 new hairs in place of the fallen ones. Among the acute diseases, 

 typhus, and of the chronic ones, syphilis, are the most frequent causes 

 of defluvium capillorum, as this latter form of falling of the hair is 

 called. Severe pneumonia, however, and nearly every other exhaust- 

 iug disease, and in a slighter degree the puerperal state, almost al- 

 ways occasion more or less loss of the hair. Alopecia circumscripta 

 seu area Celsi also seems to depend upon temporary derangement of 

 the nutrition of the hair-follicles. In this -complaint, which is not un- 

 common, round spots of variable size appear upon the head, or, as is less 

 usual, upon the beard, or upon other regions, in which the hairs break 

 off close above the roots, split into brushes, and fall out, so as event- 

 ually to form a bald spot closely surrounded by a dense growth of 

 hair. The skin of the bald spot appears perfectly healthy, and this 

 will readily enable us to distinguish alopecia circumscripta from herpes 

 tonsurans, which may also produce round bald spots upon the skin. 

 The cause of alopecia circumscripta is unknown. It is not due to the 

 presence of a vegetable parasite. After a while the bald spot is once 

 more covered with healthy hair. Loss of the hair induced by inflam- 

 mation of the scalp, and by parasites (favus, herpes tondens), is to be 

 treated of by-and-by in its appropriate chapter. 



In very old persons the hair almost always loses its color, 

 and, according to the observations of jSeitz, the discoloration begins 

 at the tip, and extends rapidly i. e., in a few days over the 

 whole hair. Now and then the hair loses color throughout its whole 

 extent from the first. The hair of young persons also loses its color 

 sometimes, and it then often takes place more rapidly than is usually 



