ANTHROPOMETRIC LABORATORIES 257 



impression is usually made by what may be described 

 as the crests of the mountain ridges of the pattern ; 

 a strong pressure will show the connecting cols as 

 well, so the latter are unimportant. Decipherment 

 is a peculiar art. Gross differences are conspicuous 

 enough to an untrained eye, but even in these a novice 

 may sometimes contrive to make mistakes when an 

 imperfect impression is submitted to him. On the 

 other hand, the art of taking good prints is very easy, 

 and may be learnt in a single lesson by any intelligent 

 and handy man. 



Much has been written, but the last word has not 

 been said, on the rationale of these curious papillary 

 ridges ; why in one man and in one finger they form 

 whorls and in another loops. I may mention a 

 characteristic anecdote of Herbert Spencer in con- 

 nection with this. He asked me to show him my 

 Laboratory and to take his prints, which I did. Then 

 I spoke of the failure to discover the origin of these 

 patterns, and how the fingers of unborn children had 

 been dissected to ascertain their earliest stages, and so 

 forth. Spencer remarked that this was beginning in 

 the wrong way ; that I ought to consider the purpose 

 the ridges had to fulfil, and to work backwards. 

 Here, he said, it was obvious that the delicate mouths 

 of the sudorific glands required the protection given 

 to them by the ridges on either side of them, and 

 therefrom he elaborated a consistent and ingenious 

 hypothesis at great length. 



I replied that his arguments were beautiful and 

 deserved to be true, but it happened that the mouths of 

 the ducts did not run in the valleys between the crests, 

 but alono- the crests of the ridges themselves. He 



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