ELEMENTARY FORMS. 27 



= 0-017 of a line. The length, thickness, and shape of the shaft vary 

 considerably with individuals and in different parts of the body. The free 

 extremity is frequently split. 



The hairs of the head are generally cylindrical, frequently also flat and 

 very curly (woolly hair of Negroes). 



The beard and pubic hairs, those of the axillary fossa, of the eyebrows, the 

 entrance to the nose and the ears, are oval (upon transverse section). 



The root of the hair, bulb (head of the hair according to Henle), bulbus 

 pili, is soft, viscous 1 2 lines long, below thick and hollow, containing a 

 tenacious substance, in which cell nuclei lie (as in the rete Malp.) ; farther 

 upwards, surrounded by transverse fibres, which connect firmly together the 

 longitudinal fibres; the superior extremity is uninterruptedly connected with 

 the shaft of the hair. The Medulla by degrees loses itself below. 



Outside the shaft of the hair the sheath of die root passes from the bulb, 

 which immediately continues into the Epidermis, of which it is only an in- 

 version, just as 



The Hair follicle (folliculus pili) is an inversion of the Corium. This 

 consists of fibres of areolar tissue, and terminates blindly, with a process 

 above (Pulpa), upon which the hair bulb is seated. It possesses nerves and 

 vessels, pain and blood, therefore, on wounding. Into it open the smallest 

 sebaceous (gland of the hair follicle) glands. (See, under Cutis.) 



Characters. Hairs become electrical by rubbing, and attract moisture both 

 from the air and body. They are therefore soft and shining in perspirable, 

 and brittle in dry skins. 



Chemical. Hair consists of fat and Keratose substance, the former pro- 

 bably coming from the medulla, the latter from the cortex. Boiling alcohol 

 draws out the fat containing the colouring matter, Elaine. It is acid; red 

 in red, and greyish green in dark hair. Nitric acid dissolves the hair, chlorine 

 bleaches and makes it glutinous. In the ash we find some oxide of iron, 

 oxide of manganese, and silex, together with sulphate, phosphate, and car- 

 bonate of lime. 



Growth. Hairs grow out of the highly vascular follicle, and are renewed, 

 like the nails, by deposits from below. The cut off point is not again re- 

 stored, but the piece immediately next to it is pushed from below forwards; 

 the point is also the first part generated. The first development appears 

 after the third month of fcetal life; even before birth the entire body is 

 covered with woolly hair (lanugo), which at a later period falls off. 



With puberty the beard and pubic hairs are developed, the hair in the 

 axilla, glandebalcc, and on the chest. 



NOTE. The skin of the head produces most hair (= 293 on ^ a line square), 

 more fair than brown, and more brown than black. The hair follicles gene- 

 rally lie in twos and threes in regular lines, for which a fixed point, e. g., the 

 crown of the head, serves as a centre. 



In old age the roots of the hair become knotty; the shaft, from deficiency 

 of oil, grey ; and the hair falls off. White hair is also found on Albinos. 



NOTE. Hair is sometimes found abnormally upon the mucous membrane 

 of the eye, in the gall bladder, in the ovaries [and in the thorax. Prepara- 

 tion shown to me by Dr. Munk. TRANS.] 



27. To the so-called non-organised tissues, the laminated structures 

 (Burdach), belong the Cornea and crystalline lens of the eye. (To which 

 refer.) Nearest to these we may comprehend : 



JfcS. The uniting tissue (J. Miiller) cellular, areolar or fibro-cellular, a 

 soft humid mass, penetrated by vessels and nerves, which is diffused every- 



