118 BLASTOGENIC VARIATIONS. 



The finger prints, though bearing some resemblance, 

 were nevertheless easily distinguishable. Hence in 

 this case Galton's finger-print method would serve for 

 an identification, whilst Bertillon's anthropometric sys- 

 tem would be useless. 



The very slight modifications produced in these twins 

 by the action of environment during growth is prob- 

 ably explained by the fact that they had always been 

 brought up together, and so exposed to practically the 

 same conditions all their lives. 



In another series of measurements upon twin 

 brothers (aged twelve), the differences observed were 

 somewhat greater, and the facial resemblance was like- 

 wise not quite so marked as in the previous case. The 

 boys had both had scarlet fever, chicken-pox, and 

 measles at the same times. Of the measurements given, 

 it will be seen that the span of arms and length of fore- 

 arm showed the greatest differences. As before, one 

 twin was slightly smaller than the other in respect of 

 every measurement made : 



PER CENT. 

 TWIN A. TWIN B. DIFFERENCE. 



Standing height 143.22cm. 142.62cm. - .42 



Sitting height 72.93 72.87 - .08 



Span of arms 150.73 148.81 -1.27 



Elbow to tip of mid-finger, . . . 39.59 38.93 1.67 



Length of right mid-finger, . . . 10.06 10.03 .30 

 Circumference of head (over occi- 

 pital protuberance and 2.5 cm. 



above eyebrows), .... 50.23 49.97 .52 



From the vegetable kingdom Weismann also quotes 

 an instance in support of Hensen's law. Thus, in re- 

 spect of two species of Oxalis, " the flowers of the dif- 

 ferent hybrids were by no means quite similar, but 



