Obkervations on tlie Structure of Human Hair. 335 



ver found in the adipose layer ; nor can they be confounded with 

 the bulbs of the hairs, their size being much larger than theirs. 

 Lastly, the structure of these organs is very different In new- 

 ly born children, the sebaceous foHicles may be discovered on 

 all parts of the body, excepting the two mentioned. They are 

 particularly large in the skin of the scrotum. Each of these 

 follicles is composed of four or five compartments, or cellules, 

 agglomerated together. Their transverse diameter is greater 

 than that which extends from the bottom of the excretory ori- 

 fice. The greatest transverse diameter observed by the author 

 was three-fourths of a line. 



The great development which the sebaceous follicles assume 

 in the parts of the skin which are affected with cancer or fun- 

 gus, also furnishes a proof of their existing over the whole ex- 

 tent of the skin. 



In microscopical researches respecting the structure of hairs, 

 it is of advantage to make use of a single lens, with a very small 

 focus (from one-fourth of a line to a line), in place of the com- 

 pound microscope, which often gives rise to error, in making 

 mere inequalities existing at the surface of the skin to be con- 

 founded with internal cellules. The transverse section of the 

 hairs should also be carefully examined. For this purpose, the 

 hair is placed on a piece of smooth paper, on which several pa- 

 rallel lines cut each other at right angles. The hair is fixed by 

 its two extremities with wax, and is cut with a very sharp razor, 

 placed in the direction of one of the lines which fall perpendi- 

 cularly on the hair, and with the edge directed vertically toward 

 the paper. Thus prepared, the hair presents its transverse sec- 

 tion in a very distinct manner. From inquiries made in this 

 manner, the author concludes, that the human hair has neither 

 a canal in its interior, nor a cellular structure ; an opinion al- 

 ready given out by Rudolphi, but contradicted by M. Hensin- 

 ger. It is otherwise with the hairs of the roe, they presenting, 

 in whatever manner they are examined, hexagonal cells, whose 

 diameter is placed transversely. But this hair differs from that 

 of man in many other properties. There are no cellules in the 

 woolly hair of the sheep. 



The form of the human hair is rarely cylindrical. It appears 

 to be so only in the straight hairs. In the curled hairs, the sec- 



