492 THE SOLIDS. 



where they are less numerous than on. the palmar and plantar 

 surfaces of the hands and feet. (See Plate LXIII. fig. 4.) 



On the palms of the hands and soles of the feet, the 

 papillae are arranged, as may be seen with the naked eye, in 

 lines or ridges, each ridge Jbeing made up of two rows of 

 papillae in single file, and between each pair of which a further 

 line of separation may be traced : such is the general dispo- 

 sition of the papillae in each ridge ; the ducts of the sudori- 

 ferous glands pass through its centre, and between the 

 rows of papillae, the number of these glands and ducts to 

 that of the papillae being in the proportion of one to four. 

 ( See Plate LXIII. fig. 3.) 



The arrangement just described can be well seen on the 

 palms of the hands by the aid of a lens, even while the 

 epidermis is still attached to the cutis ; the ridges are seen 

 to be disposed here and there in beautiful curves, some 

 abruptly coming to a termination, and others dividing into 

 two distinct ridges, this disposition enabling them to adapt 

 themselves more accurately to the varying nature of the 

 surface over which they are extended : along the middle of 

 each ridge, the apertures of the numerous sudoriferous glands 

 may be seen for the most part crossed in the direction of 

 the diameter of the ridge by a faint groove, which indicates 

 the line of separation of the papillae into pairs. (See 

 Plate LXIII. fg. 1.) 



Each papilla appears to consist of a prolongation of base- 

 ment membrane, and contains in its interior granular and 

 nuclear contents and a single looped blood-vessel, (see 

 Plate LXIII. Jigs. 3. 7.) : these points of structure are all 

 made out readily enough ; the chief difficulty consists in the 

 determination of the manner in which the nerve filaments, 

 with which the papillae are undoubtedly supplied, terminate 

 in them. On this subject, Messrs. Todd and Bowman * 

 have the following observations : "In regard to the pre- 

 sence of nerves in the papillae themselves, we can affirm 

 that we have distinctly traced solitary tubules ascending 



* Physiological Anatomy, p, 412. 



