196 SPECIAL HISTOLOGY. 



eyelashes. The hairs of the head, and the other hairs of the 

 body of the child (almost a year old) in question, never con- 

 tained more than one hair, though their bulbs presented 

 processes without hairs like those which precede the shedding 

 of the eyelashes ; such processes, in fact, being of very common 

 occurrence in the hairs of children within the first year. I 

 believe I am not wrong, if from the presence of these processes 

 I deduce the universal occurrence of a shedding of the hairs, 

 particularly as it is certain that in many children within the 

 first 2 — 6 mouths after birth, the hairs of the head fall out and 

 are replaced by new ones. However, further observation is 

 necessary to determine what period is occupied by this first 

 shedding of the hair, in what hairs it occurs, and whether 

 perhaps the process is subsequently repeated. 



[If we compare the shedding of the hairs with their first 

 development, we find a great resemblance between the two pro- 

 cesses. In both, elongated projections, wholly formed of round soft 

 cells, shoot like buds from the stratum Malpighii, in the one case 

 of the skin itself, in the other of the hair-sacs and hairs. In 

 both, a separation of the inner from the outer cells next takes 

 place; and while the latter are metamorphosed into the outer 

 root-sheath, the former become the inner root-sheath and the 

 hair. The latter arises, as is still more clear in the shedding of 

 the hairs than in their first development, like the nail, with all 

 its parts at once, as a small hair provided with point, shaft, and 

 root, and which only subsequently begins to grow, in con- 

 sequence of which it enlarges in all its parts, and finally 

 reaches the surface. The differences between the two modes 

 of development are very inconsiderable, and chiefly depend 

 upon the rudimentary hair-processes, in the one case proceeding 

 from the hairs themselves, but not in the other ; and upon the 

 circumstance that the young hairs, although in both cases they 

 lie at first in a closed space, reach the surface more readily in 

 the one case, than in the other. 



In the periodical shedding of the hair of animals, the 

 observations of Heusinger and Kohlrausch, and lately those of 

 Lauger, Gegenbaur and Steinlin, show that the new hairs are 

 also developed in the sacs of the old ones ; although, according 

 to the last author, with whom however Langer is not qtiite in 



