POPULAR SCIENCE MONTHLY. 



The great individual variation of these parts in the human being 

 is not without significance and furnishes an excellent illustration of 

 the biological truth that the perfection and constancy of an organ are 

 directly 'proportional to its necessity in the life of the organism. Thus 



Fig. 4a. Fig. 46. 



Fig. 4. Tracings from Palm Prints, showing Range of Variation. 



in an arboreal primate, an exact appreciation of the contact surfaces 

 of the tree-boughs among which it climbs and swings is of vital impor- 

 tance, and the slightest defect or deviation from the standard in the 

 organs furnishing that intelligence would be apt to prove fatal; but 



Fig. 5a. Fig. 56. 



Fig. 5. Tracings from Sole Prints, showing Range of Variation. 



when such a being assumes a terrestrial life, so high a degree of sensi- 

 tiveness in palms and soles is no longer necessary and the organ is 

 allowed to lapse. Individual variations, no longer discouraged, tend 

 to increase, and that which was once a necessary and vital arrangement 



