IV.] 



MINUTE MODIFICATIONS. 



121 



vertebrate fin-limb. In the ichth3''osauriis, in the plesio 

 saiirus, in the whales, in the porpoises, in the seals, and in 

 otliers, Ave have shortening- of the bones, but no reduction 

 in the number citlicr of the fnigers or of their joints, which 

 are, on the contrary, multiplied in Cetacea and the ichthyo- 

 saurus. And ev(Mi in (he turtles we have eight carpal 

 bones and five digits, while no finger has less than two 

 phalanges. It is diflicult, then, to believe that the Avian 

 limb was developed in any other way than by a compara- 

 tively 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 pro- 

 duced by minute modifications ? These, according to Mr. 

 Darwin," oscillate till they touch an object, and then em- 

 brace 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 JPassiJfora gracilis^ will cause 

 it to bend ; and merely to touch iho tendril with a twig 

 causes it to bend ; but if the twig is at once removed, the 



SKELETON OF AN lOIITIlTOBAURnS. 



tendril soon straightens itself. But f^ie contact of other 

 tendrils of the plant, or of the falling of drops of rain, do 

 not produce these effects."^ B'.it some of the zoological and 

 anatomical discoveries of la<.<' years tend rather to dirniiiish 

 than to augment the evidence in favor of minute and grad- 



5« Quartcrh/ Journal of Science, 1866, pp. 25Y, 268. 

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

 



