OF THE SKIN. 1 l«.) 



be regarded as belonging to the horny layer and two thirds to 

 the rete Malpighii. In a somewhat older embryo it was, on 

 the heel 006 — -064'" (mucous layer 0-05, horny layer 00 1 — 

 0-014/"), on the surface of the hand 005 '" (mucous layer ()()!. 

 horny layer 0-01'"), on the back 0-02— 0024'" (mucous and 

 horny layers of equal thickness). The mucous layers consisted 

 of many layers of smaller cells, the lowest of which were already 

 elongated, and stood perpendicularly ; the horny layer, of at 

 least two layers of polygonal flattened cells, with round nuclei. 



In the sixth month the epidermis upon the thorax measures 

 002— 0-022"', on the palm of the hand 06'", on the sole of the 

 foot 0-07"', and everywhere it consists of many layers of cells. 

 The outermost one or two are composed of horny plates without 

 nuclei 0*01 — 014'" perfectly similar to those of the external 

 horny layer in adults; then follow 3 — 4 layers of polygonal 

 cells, the largest -001 — 0-01 2'", with nuclei 0-004"'; finally a 

 mucous layer, whose thickness equals about one half or two 

 fifths that of the whole epidermis, with at least 3 or 4 layers 

 of rounded cells of 0003 — 0-004"', the lowest of which are some- 

 what elongated, and are seated perpendicularly upon the cutis. 



In the seventh month, I found in one embryo, that the 

 epidermis on the heel measured 0*12'" (mucous layer 0072,"' 

 horny layer 0-048'"), upon the back O-O?'" (mucous layer 004'", 

 horny layer 003"') : iu another it measured on the heel 0-12 — 

 0'14'" (mucous layer 0-05— 0-06'", horny layer 007— 0-08"'), 

 on the knee 0-046— 0-064'" (mucous layer 0-01G — 0-024'", horny 

 layer 003 — 0-04'".) Both layers of the epidermis are as sharply 

 separated from one another as in adults, and their elements 

 similar to those of the perfect epidermis, especially the lowest 

 parts of the stratum Malpighii and the plates of the horny 

 layer, which have no nuclei, aud measure 0-01 — 0-014" in the 

 uppermost layers. 



In the new-born infant, apart from the thickness of the epi- 

 dermis, which in one case measured on the heel 0-1 — 0-11" 

 (mucous layer 004 — 0-05'", horny layer 006'") nothing 

 particular is to be observed, except that by maceration, &c, 

 it is much more easily separated from the curium than 

 in the adult. The non-nucleated horny plates measured 

 0012 — •016", on the labia minora where they possess nuclei 

 0-016—0-02". 



