SECT. 41.] CUTIS. 83 



also of connective tissue and vessels. In this way, the skin con- 

 tinues to grow for a long time after birth (thus in children the 

 corium is, according to Krause, only half as thick as in the adult), 

 till at length, but at a time as yet undetermined, the new formation 

 of cells ceases, and also, at a much later period, the extension of 

 the already-formed elements, cells, fibres, etc. The fat-cells, in 

 which the process of growth is especially perceptible, are, according 

 to Harting, in adults, in the cavity of the orbit twice, in the palmar 

 surface of the hand three times the size of those in the new-born 

 child; whence it follows that they enlarge in proportion to the 

 parts of the body to which they belong. 



The skin, in embryos two months old, is o , oo6'" to o'oi'" 

 thick, and entirely made up of cells. In the third month, it 

 amounts to 0*06'", and already possesses tolerably evident con- 

 nective tissue. In the fourth month, the first fat-lobules arise, 

 together with the ridges on the hand and sole of the foot. In the 

 sixth month, the skin measures 06'" to 07'", and the papillce 

 become developed. From the seventh month onwards, the pan- 

 niculitis adiposus is very much increased, and is, at birth, relatively 

 thicker than in the adult. 



§ 41. Physiological Remarks. — When we endeavour to bring the 

 anatomical data, communicated above, into unison with the phe- 

 nomena of sensation of the skin, we encounter very considerable 

 difficulties. The more minute anatomy of the skin, as at present 

 known, fails to demonstrate nerves in all the papillae, or even in 

 the majority of them ; and, nevertheless, experiment shows that all 

 parts of the skin are sensitive, although not with equal acutcness. 

 As the papillae which contain nerves are but scanty in the palm of 

 the hand, and in other places very rare, or even not to be demon- 

 strated, we are obliged either to lay down the hypothesis, that all 

 papillae contain nerve-tubules destitute of white substance, or to 

 have recourse to the nervous plexuses at the bases of the papillae. 

 I must, for the present, prefer the latter explanation, although 

 these plexuses are, in many places, so scanty, that it appears almost 

 impossible, by means of them, to explain the fact, that the slightest 

 contact of the epidermis produces sensation. If we are not in a 

 position to explain how every part of the skin is sensitive, Ave are 

 still less able to offer an explanation of the various kinds of sensa- 

 tions. Nevertheless, the following considerations may be stated as 

 to the latter question : 



o 2 



