Dr Bidder's Bemarks on the Human Hair. 165 



quantity of vegetable matter sufficient to produce a given 

 thickness of coal, and also of the amount of shrinkage the ve- 

 getable matter has undergone by conversion into solid coal. 

 TMs evidence is principally derived from the existing laws of 

 vegetable physiology applied to the remote epoch of the coal- 

 formation under modifications necessary from difference of 

 climate and other circumstances. But as the details, however 

 interesting in the present state of our knowledge, or rather 

 ignorance on these points, are not necessarily connected with 

 the subject of fossil trees, and cannot easily be explained with- 

 out a diagram, it is perhaps better not to introduce them into 

 the present communication. 

 Manchester, Jmie 1841. 



Remarks on the Origin, Structure^ and Life of the Human Hair, 

 By Dr Bidder of Dorpat. 



By means of Schwann''s admirable investigation of the de- 

 velopment of the textures, the only sure path has been opened 

 up by which the explanation of many obscurities in the mi- 

 croscopic relations of the textures, and the final solution of 

 many disputed problems connected with these have either been 

 already actually obtained, or may be expected. To the latter 

 belong the discussions, continued up to the present day, on 

 the structure of the human hair. For, the hollowness or the 

 solidity of hair, the division into two different substances, or a 

 perfectly uniform constitution, the fibrous structure imagined 

 by Leeuwenhoek, or some other cause of the longitudinal divi- 

 sion sometimes seen in hair ; these were questions, the perfcc t 

 and sure decision of which could only be expected from the 

 history of the development of these parts, and from the deter- 

 mination of their relation to the primary cells. Unfortunatel}', 

 Schwann, although he directed his attention to most of the 

 modifications of the horny texture in this point of view, did 

 not investigate the hair. Perhaps, therefore, the communica- 

 tion of some observations on this subject may not be without 

 interest. 



The investigation of the mode of formation of the parts be- 

 longing to the horny texture is rendered very easy by the cir- 



