ANIMAL NATURE OF DIATO.ME/E. 503 



but of a low degree, and is also the product of secretion 

 from another more noble and complex element of the body 

 over which it is extended. What is this generating ele- 

 ment? This is a necessary inquiry, and not less impor- 

 tant than interesting to the physiologist and medical prac- 

 titioner. This element certainly forms part of the tegu- 

 inentary membrane, in which the epidermis constitutes 

 the ultimate layer and most superficial covering. I do not 

 believe that it can be the follicles or crypta, because these 

 minute organs afford mucus, oil, or cerumen, a liquid 

 adapted to lubricate, but not to organise, capable of 

 accumulation, but not of concretion ; for when once 

 covered with epidermis, we cannot conceive how their 

 apertures can still secrete oil (scgo) or any other liquid 

 whatever ; so that if the cutis be considered as the same 

 with the mucous follicles, the epidermis is thin where these 

 are abundant, and, again, it presents the greatest thickness 

 where these are rare, or absent, as in the palm of the 

 hand, or the sole of the foot ; finally, because very often 

 in morbid thickening of the epidermis, we do not find 

 the follicles varying from their natural condition. But I 

 believe that the organs producing the epidermis, at least 

 in most places, and in most instances, are the papilla 

 which possess so many vessels of every kind, that we 

 cannot suppose them wanting in the function of se- 

 cretion. And indeed we observe that wherever the 

 papilla3 are most numerous, most developed, and most 

 vascular, there the epidermis is the most manifest. It 

 is thickest on the palms of the hands and the soles of 

 the feet, where, to serve the office of touch, the papillae 

 are most numerous, and are organised and arranged in a 

 particular manner. It is thickest on the tongue, where 

 the sense of taste requires an abundance and prominence, 

 of the papillary organs. And speaking of mucous mem- 

 branes, wherever they exist there also exist sensitive 

 papilte, animated by nerves of sense, that is in the 

 vicinity of the natural orifices of the body. According 

 to the most recent teachers of pathological anatomy, and 



