SOCIETY OF THE UNIVERSITY OF ABERDEEN. 3 



of these the so-called insignificant finger-prints are of the first im- 

 portance. The general appearance may change, the height may 

 increase or decrease, the features may be greatly modified, but the 

 finger-prints cannot be altered or removed. 



Closer examination of the ridges reveals the fact that they are 

 studded with minute pores which are the open mouths of tiny sweat 

 glands. The ridges grow simultaneously with the general growth of 

 the body. At birth the delicacy of the ridges is in proportion to the 

 smallness of the stature. In old age, on the other hand, the sharp- 

 ness of definition becomes blurred. They are developed most in 

 hands that do a moderate amount of work. They are often obli- 

 terated in the hands of labourers and artisans by the constant pressure 

 of their peculiar tools. Ridges on the sides of the left forefinger of 

 tailors and seamstresses are often temporarily destroyed by the needle. 



The use of the ridges is to raise the mouths of the ducts. They 

 aid, too, the sense of touch by enabling the character of surfaces to be 

 perceived by rubbing them with the fingers. 



With regard to the taking of finger-prints. In this Laboratory 

 finger-prints are taken with printer's ink. A few drops are let fall 

 on a slab and worked with a roller into an even layer. The palmar 

 surface of the finger is placed on the slab and rolled, the object being 

 to secure the inking of the whole surface. The process is repeated 

 upon a white ground, and the result is a print where the ridges are 

 marked in black and the furrows remain white. Prints can also be 

 taken on smoked glass, on sealing-wax and on gutta-percha. Many 

 are, however, taken in a simpler way, for tell-tale prints have been 

 found on the panels of doors, on the window-ledge, on the dust of 

 shelves and even in blood on the window-panes. 



When the finger-prints have been secured they must next be 

 classified. This is done after Gal ton, placing the print in either of 

 three classes Arch, or Loop, or Whorl. Galtou terms this his pri- 

 mary classification. A clear understanding of all that determines an 

 arch, a loop or a whorl is essential before going further. A pattern 

 is said to be an arch when the ridges run from one side to the other 



