1887.] NATURAL SCIENCES OF PHILADELPHIA. 57 



uniformly amongst the smaller or less developed hair germs, which 

 were everywhere far more numerous, being very probably the germs 

 of the Avoolly coat or under-pelt. 



It is possible that these larger hair germs represent the rudiments 

 of hairs, which are more particularly sensory in function, and which, 

 like the vibrissse about the snout, and the groups of tactile hairs 

 above the eyes, and the two groups on the cheeks of many mammals 

 are more richly supplied with sensory nerves than others. The 

 distribution of such tactile hairs in the Mammalia, was also consid- 

 ered by the speaker, who referred to the studies of Eschricht, Stan- 

 nius and his ow^n, on the distribution of such tactile hairs on the 

 snouts of the foetuses of various genera of Cetaceans, in which group 

 it had been ascertained that they furnished very good characters 

 diagnostic of species. It was also suggested in support of the view 

 that larger hair germs on the body and head of the foetal cat, w^ere 

 sensory in function, since they seemed to be arranged in conformity 

 with the color areas on the back, which, as had been pointed out by 

 Prof. Harrison Allen, were the recipients of special branches of the 

 superior twigs of the intercostal rami of the spinal nerves in certain 

 animals, ( Tamias.) Hairs with a special function have also been 

 found in other regions in the skin of mammals ; as for example, 

 certain hairs described by Schobl on the interdigital wing mem- 

 branes of bats. 



Upon reflection, however, the preceding view of the facts bearing 

 upon the development of two kinds of hair germs in the skin of the 

 foetal cat, were not wholly satisfactory. It was therefore deemed 

 best to subject the skin of the foetus in question to still more search- 

 ing scrutiny. A portion of the skin from the top of the cranium of 

 the foetus was, therefore, carefully pealed off, stained in borax car- 

 mine and cut into sections and mounted as a series. This series of 

 sections revealed several very interesting points, which it Avas impos- 

 sible to make out from a more superficial examination. 



It Avas found that the epidermis at this stage was only five or six 

 layers of cells deep, and that there were two very sharply defined 

 types of hair germs growing downwards from it into the corium. 

 The larger and more advanced of these hair germs or follicles were 

 very much thicker and larger than the others, and had penetrated 

 more deeply into the underlying corium, than the less developed 

 ones. At the point where the larger germs joined the epidermis, the 

 latter was thickened so as to form the elevations marking the posi- 



