272 THE SOLIDS. 



pubis, abdomen, and chest ; this development is an effect of 

 the great functional activity which exists at that period, and 

 which is the occasion of the increased and rapid growth of 

 the several constituents of the body which then takes place. 



The earliest periods at which the rudiments of hairs in the 

 human foetus have been observed is from the third to the 

 fourth month : the hair follicle is formed in the first place, 

 next the bulb, and then the sheath and stem of the hair, 

 which, in the early period of its development, is curved 

 upon itself. 



Hairs are occasionally developed in certain peculiar situa- 

 tions, as on the mucous membrane of the conjunctiva, the 

 intestines, and gall bladder, in the ovaries, and in steatoma- 

 tous and encysted tumours. 



Hairs may be transplanted, and, it is said, will grow after 

 such transplantation in consequence of the adhesions and or- 

 ganic connexion established between them and the adjacent 

 tissues, a fact of which practical advantage might be taken 

 if correct. 



When a hair has obtained the full term of its develop- 

 ment, according to the researches of Eble, it becomes con- 

 tracted just above the bulb : this change probably announces 

 its death and approaching fall. 



REGENERATION OF HAIRS. 



Hairs are peculiarly susceptible of being affected by the 

 condition of the health, even more so than the epidermis. If 

 this be vigorous, as a rule to which there are many exceptions, 

 it will be found that the hairs themselves are thick and firmly 

 set in the skin : if, on the contrary, the powers of the system 

 be debilitated from any cause, the hair will either fall off 

 spontaneously, or a very slight degree of force will serve to 

 dislodge them from their connexions. 



If the bases of those hairs which fall out of themselves be 

 examined, or which are removed by combing and brushing, 

 it will be seen that the bulb alone has come away, the entire 

 sheath and germ remaining behind. In such cases the hair 



