IV.] MINUTE MODIFICATIONS. 121 



turtles we have eight carpal bones and five digits, while no 

 finger has less than two phalanges. It is difficult, then, to 

 believe that the Avian limb was developed in any other 

 way than by a comparatively sudden modification of a 

 marked and important kind. 



How, once more, can we conceive the peculiar actions of 

 the tendrils of some climbing plants to have been produced 

 by minute modifications ? These, according to Mr. Darwin, 1 

 oscillate till they touch an object, and then embrace it. It 

 is stated by that observer, " that a thread weighing no more 

 than the thirty-second of a grain, if placed on the tendril 

 of the Passiflora gracills, will cause it to bend ; and merely 

 to touch the tendril with a twig causes it to bend ; but if 

 the twig is at once removed, the tendril soon straightens 

 itself. But the contact of other tendrils of the plant, 

 or of the falling of drops of rain, do not produce these 

 effects." 2 



Some of the zoological and anatomical discoveries of 

 late years tend rather to diminish than to augment the 

 evidence in favour of minute and gradual modification. 

 Thus all naturalists now admit that certain animals, which 

 were at one time supposed to be connecting links between 

 groups, belong altogether to one group, and not at all to 

 the other. For example, the aye-aye 3 (Chiromys Madagas- 



1 Quarterly Journal of Science, April 1866, pp. 257-8. 



2 "Habit and Intelligence," vol. i. p. 178. 



3 This animal belongs to the order Primates, which includes man, the 

 apes, and the lemurs. The lemurs are the lowest kinds of the order, and 

 differ much from the apes. They have their head-quarters in the Island 

 of Madagascar. The aye- aye is a lemur, but it differs singularly from all 

 its congeners, and still more from all apes. In its dentition it strongly 

 approximates to the rodent (rat, squirrel, and guinea- pig) order, as it has 

 two cutting teeth above, and two below, growing from permanent pulps, 

 and in the adult condition has no canines. 



