Structure^ and Life of (he Human Hair. 169 



of decomposing the fully developed hair into its fibrous ele- 

 ments. The successful treatment, with concentrated acids, of 

 the nails by M. J. Weber, and of the epidermis by Henle, sug- 

 gested itself. This method afforded the desired results. I 

 found that a maceration for several vs^eeks in muriatic acid 

 was the most effectual. The hair is in this way rendered so 

 soft that by slight pulling it is torn asunder ; it can be split 

 into longitudinal threads even by rough preparation, and, by 

 pressure in the direction of the breadth, it can be as completely 

 separated as can be wished for microscopical investigation. 

 There appear coarser and finer fibres uniting with one another 

 in a plexus-like manner, and crossing one another in the most 

 varied directions ; the deviation from the parallel course is 

 doubtless a consequence of the preparation. In the thinner 

 fibres some resemblance to elastic fibres is produced by fre- 

 quent union. But even these fibres are bundles of numerous 

 fine fibrils. These, the elementary forms of the hair, present 

 themselves as dark lines, becoming from place to place a little 

 broader, and even at these broader spots, which are the re- 

 mains of earlier cellular bodies, possessing a diameter of only 

 0.00041'", according to an estim^e made of it at these very 

 spots, which, indeed, are the only portions sufficiently broad to 

 admit of being calculated. They are, therefore, the finest of 

 all the elements of the body hitherto ascertained. I must remark 

 that the observer may easily be exposed to a double deception 

 in respect to the numerous fibres that occur, which exhibit a 

 lighter centre, surrounded by dark bounding lines, and which 

 might be regarded as the elementary constituent parts of hair. 

 On the one hand, by the position of the microscope being 

 altered, such a fibre will sometimes have the aspect of a 

 bundle of the already-mentioned finest fibrils, which are 

 somewhat united by the yellowish cytohlastema^ which has 

 been again loosened and swollen by the acid, whence such a 

 bundle also presents a yellowish colour, with dark streaks 

 running through it. On the other hand, in such an altered 

 position of the microscope, the observer can at pleasure allow 

 the one boundary line to appear or disappear, while the other 

 remains constant, or, inasmuch as he can allow the light which 



