HAIR. 



127 



of the microscope ; and Dr. Bostock 1 affirms, that he had an opportunity 

 of viewing the human hair, and the hair of various kinds of animals, in 

 the excellent microscope of Mr. Bauer, but without being able to observe 



Thin Layer from the Scalp. 



a, a. Sebaceous glands, b. Hair, with 

 its follicle, c. (Gurlt.) 



Magnified view of the Root of the Hair. 



(Kohlrausch.) 



a. Stem or shaft of hair cut across, b. Inner, and e. 

 Outer layer of the epidermic lining of the hair follicle, 

 called also the root-sheath, d. Dermic or external coat 

 of the hair follicle, shown in part. e. Imbricated scales 

 about to form a cortical layer on the surface of the hair. 



it. Bichat, 2 however, and more recently, Dr. Goring, 3 and most histolo- 

 gists, have assigned this as their structure; and the author has had 

 repeated opportunities for confirming it with his own admirable micro- 

 scope, made by Smith, of London. 



Modern observers believe, that, as in other structures, growth takes 

 place from cells, which are a modification of those of the epidermis. 

 The primary cells become elongated, and generate within themselves 

 fasciculi of fibres or secondary cells, which interlace to form the hair 

 cylinder. The walls of these fibre-cells are at first soft and permeable; 

 and the lower part of the hair, which is composed of them, seems to 

 admit the passage of fluid without much difficulty. At a short distance 

 from the base, the horny character of the hair, caused by the deposit of 

 horny matter in the interior of the fibres, becomes apparent. "There 

 is then, at the base, a continual formation of soft fibrous tissue, by 

 which the length of the cylinder is increased; whilst at a short distance 

 above it, there is a continual consolidation of this (as it progressively 

 arrives at that point) by the deposit of a peculiar secretion in its 

 substance." 4 



Physiology, p. 52, 3d edit., Lond., 1836. 



3 Journal of Science, New Series, vol. i. 433. 



< Carpenter, Human Physiology, 637. Lond., 1842. 



Anat. General., torn, iv., 2. 



