98 THE POPULAR SCIENCE MONTHLY. 



which diminish in size by frequent branching as they converge toward 

 the top of the head. They are in a most favorable position to be com- 

 pressed, lying on unyielding bone and covered by thin tissue. Con- 

 sider what effect must be produced by a close-fitting, heavy, and rigid 

 hat : its pressure must lessen to a certain extent the flow of arterial 

 blood, and obstruct to a greater extent the return of the venous ; the 

 result being a sluggish circulation in the capillaries around the hair 

 follicles and bulbs, a consequent impairment of nutrition, and final 

 atrophy. This pressure is not trivial or imaginary, as any one will 

 admit who has noticed the red band of congestion on the forehead 

 when a hard hat is removed after moderate exercise. If the man is 

 bald, the red pressure-mark can be seen all around the head. 



It may be asked, Can the wearing of a tight band around the head 

 for a few hours a day have any perceptible effect on the growth of 

 the hair ? That the hair-bulbs are susceptible to disturbances of nu- 

 trition is evident from the effect of a continued fever, or any wasting 

 disease, where nutrition is seriously impaired. They (the hair-bulbs) 

 suffer with the general system ; the hair has been starved to death, so 

 to speak, and comes out in large quantities, sometimes amounting to 

 temporary alopecia. If the hair-crop can be thus destroyed by three 

 or four weeks of constant lessened nutrition, it is reasonable to sup- 

 pose that the same cause, though slight and intermittent, will in time 

 produce the same result. 



The course of an ordinary case of baldness corresponds with this 

 view. We observe usually a thinning out of the hair at the poll of 

 the head, or part corresponding to the posterior fontanelle of infancy ; 

 a patch appears two or three inches in diameter like the tonsure of a 

 priest. Or, instead, the thinness may begin above the forehead, but 

 in every case, the hair disappears first where the circulation is weakest 

 that is, along the top of the head, the region most remote from ar- 

 terial force. The sparseness, at first slight, becomes year by year more 

 apparent, and, finally, a bare and polished surface is presented which 

 gradually descends to the hat-band and there stops. Mark this point, 

 it never goes below the rim of the hat. I admit that the line of de- 

 nudation does not in some cases correspond exactly with the hat-band ; 

 it will be noticed that the coincidence is accurate enough at the back 

 of the head from a point opposite the top of the ear on one side to the 

 corresponding point on the other, but in front of this on either side is 

 often a tuft above the horizontal line that still maintains its growth. 

 The explanation is, that the temporal muscle, occupying the hollow 

 space in the temporal bone, acts as a cushion, thus relieving the press- 

 ure on the blood-vessels. In men with rounded heads, full in this 

 region, a continuous line will be observed. 



Before leaving this part of the subject I would direct attention to 

 the complete change effected in the scalp after the disappearance of 

 the hair. Unlike the thick, stiff, glandular structure it formerly was, 



