MINUTE ANATOMY OF PAPILLARY RIDGES 79 



parts rise out of the adjoining furrows at an angle, so that the 

 distal side of the ridge forms an acute and the proximal side 

 of the ridge an obtuse angle with the plane of the skin. This 

 gives rise to a condition which I called imbrication of the papillary- 

 ridges * ; and it is not unUke the arrangement of the tiles on the 

 roof of a house. The effect of it is to expose the edges of the 

 ridge to a more efficient contact on the distal than the proxi- 

 mal side of the ridge, and as, I beheve, to increase very much the 

 power of the human hand to discriminate between the surfaces 



Fig. ij2c. — Man. x25. Manus D. 4. Terminal phalanx, papillary ridge 

 imbricated in distal direction ; papilUo of corium double. 



of different objects. This arrangement of the angles may be 

 reversed so that the imbrication may be proximal instead of 

 distal. It is necessary to mention here that the angle of the 

 papillary ridges is closely followed by the underlying papillae of 

 the corium which also slope forward in this case. These points 

 are exemphfied in the microphotograph here shown of a section 

 of skin taken from the tips of the fourth digit of a young man's 

 hand. 



A few observations have been made as to the variability of 

 this phenomenon of imbrication of the papillary ridges of the 

 human hand and foot. The details of these are given in an 

 appendix, but the results may be summed up as follows : 



* Imbrication of the Papillary Ridges in Man, Journal of Anatomy and 

 Physiology, vol. xxxix. 



