Harris Hawthorne Wilder 447 



appear if we count the ridges composing areas limited by the main lines, 

 but in these cases we must remember the semi-artificial character of the 

 lines themselves, and the fact that in tracing them there is frequently 

 a point, caused by the forking of a line, the interpolation of a new one 

 or some similar structure, where the decision is an arbitrary one, and 

 that such a variation, although minute at first, may often make consid- 

 erable difference as the line is continued. For example, we may take 

 in the same prints the two lines B and C at their termination between 

 the 4th and 5th digits. In x they are apparently five ridges apart at 

 the margin and but three (or four) in y, differences which may easily 

 have been made in two copies of a single hand by swerving the course of 

 the lines as much as permitted by the ridges. There is, however, too 

 much difference in the same two hands at certain other places, as, for 

 example, the distance between lines B and D at the lower curve, to 

 account for it in any such way. In x this distance is expressed by an 

 average of seven ridges, while at no place in y are there less than fifteen. 

 This occasional wide discrepancy in the number of ridges suggests 

 that we are on the border between characteristics which are duplicated 

 and those which are not. AVhile the correspondence between the main 

 lines and areas, the patterns and other figures, and even the number of 

 ridges in most cases is nothing short of remarkable, the law seems to 

 fail at about tlie latter point, and if' we turn to the " yninutice " of the 

 ridges, that is, the forkings, interruptions, interpolations and isolations, 

 we find that the limit of resemblance has been passed and that whatever 

 law of heredity or of construction has caused a similarity of form or 

 arrangement in ihe larger parts, it is here no longer binding. Perhaps 

 in this way we may be led to approximate the answer to the question 

 asked by Galton : " What is the minutest biological unit transmissible 

 by heredity ? " since in individuals that arise from one egg and thus 

 possess, presumably, the same- inheritance, the main lines, areas, pat- 

 terns and other large features are duplicated exactly, or as nearly as 

 the ridges will allow them to be, while the ridges themselves with their 

 minutice are not. To illustrate this, apply a lens to the corresponding 

 areas of any two duplicate prints, as, for example, the areas in the left 

 palms of No. I designated by a small x, and follow the details of the 

 ridges. If we compare either the short detached pieces known as 

 " islands," the forkings or the interruptions, we shall see that in 

 these details the two areas are as individual and distinct as are any 

 two corresponding areas in hands entirely unrelated. They are like 

 two duplicate pieces of masonry built with irregular blocks of stone 

 taken haphazard, and show clearly that ivhile in each egg (i. e., each 



