82, CUTTS. [sect. 40. 



the sole of the foot, 7 to 8. With respect to their size, Meissner found those 

 on the palm J>" — &"— T y" long, and J/' — Vn"' broad ; those of the dorsal sur- 

 face of the fingers, ' '" — ,'</" m length and breadth ; those on the heel, ■}*' — 

 5V" in length and bi*eadth. 



In the hand, the corpvscula tactvs are seen more especially in the compound 

 papilla?, in peculiar, more or less distinct, mostly short, but often longer points ; 

 more seldom, they occur in simple papilla. 



Frequently, especially after the addition of acetic acid, they present here 

 and there constrictions, and sometimes a spiral form, so that they often come 

 to have a certain resemblance to a bundle of areolar tissue treated in the 

 same manner, or to a spiral sudoriparous duct. In other places, the papillae 

 contain no tactile bodies and no nerves, and the manner in which the latter 

 terminate is entirely unknown. 



The elements of the nerves of the skin do not present any special pecu- 

 liarities. In the small nerve-trunks, in the subcutaneous cellular tissue, some 

 of the fibres measure as much as o - oo5'" and o - oo6'", which is also the 

 case in the deepest portions of the corium ; while towards the surface they 

 all become gradually finer. In the terminal plexuses, I find they vary in 

 different localities from 0-003'" to o - ooi6'"; lastly, in the papillse, from 

 o"ooo8'" to o'ooz"'. 



§ 40. Development of the Cutis. — The following may be con- 

 sidered as an outline of the development of the cutis in the foetus : 

 The corium consists, at first, of cells, which, although not in 

 man, may in animals {e.g. the frog) be traced back to the first 

 formative cells of the embryo. A large portion of these cells are 

 converted into connective tissue, becoming spindle-shaped, blending 

 together, and being metamorphosed into bundles of fibrils. This 

 process, to all appearance, takes place first in the fascia super/icialis 

 and the subcutaneous cellular tissue; next in the reticular, and 

 lastly, in the papillary part of the corium. Another portion of the 

 cells are changed into vessels and nerves, as can be followed to some 

 extent in man, and very beautifully in the batrachia (see my me- 

 moir in Ann. d.Sc.Nat., 1846) ; a third part, finally, are converted 

 into elastic fibres and plasm-cells, and by the formation of fat in 

 their interior, into fat-cells (see above). When the first foundation 

 of all these parts has been laid, they increase in a manner which 

 is not yet in all points ascertained. The corium grows evidently 

 from within outwards (so that the papillae are the last to be formed), 

 partly b}^ the growth of its original elements, partly through means 

 of cells, which possibly proceed from the original formative cells. 

 The panniculus adiposus increases, likewise, partly by the enlarge- 

 ment of its primitive cells, partly by the formation of others, as 



