HEREDITY OF ACQUIRED CHARACTERS 203 



but the argument of Adaptation applies equally well to animals. 

 Thus just as the dissected type of foliage has been acquired 

 under water, so the "paddle" form of limb has been evolved 

 by use in aquatic animals, or in some of an amphibious habit. 

 Thus it occurs in the Crustacea, in fins of fishes, in extinct 

 marine reptiles, as the Ichthyosaurus and Flesiosaurus, etc., in 

 modern cetacea, the seals, in penguins and auks, and in the 

 tail of the beaver. 



Similar adaptations are seen in the bilobed tail of fishes, 

 reptiles and cetacea. 



Though organs may be similar in appearance and acquired 

 for the same purpose they may be of different origins and 

 differently constructed. Thus the tendril of a vine is a meta- 

 morphosed flowering branch, but that of the pea is a metamor- 

 phosed leaf. 



To make the tail of a cod, Nature has run the spine into 

 the upper lobe, the lower lobe being made with " hypural " 

 bones ; but in certain extinct marine reptiles, a similar bilobed 

 tail was made by the spine penetrating the lower lobe. Lastly, 

 in the horizontal bilobed tails of cetacea, the spine terminates 

 at the base, the tail having no bone within it at all. 



One more instance out of thousands, which I will leave the 

 reader to follow out for himself. If a lad wishes to walk fast, 

 he often does so on his toes ; and in a walking match the rule 

 is insisted upon that both heel and toe must be on the ground 

 at every step. Now, all running animals stand on their toes, 

 as horses, dogs, gazelles, etc., the heel being permanently up- 

 lifted in the air. 



Inductive evidence, based on innumerable instances, leads 

 to the conclusion that the habit of running being habitual, the 

 bones of the foot have become permanently adapted to the 

 action ; thereby supplying great rapidity either in escaping from 

 the carnivorous enemy or in the latter following its prey. 



I mention these few instances to show the versatile power 

 of protoplasm ; which can turn any organ to account for con- 

 structing something different, if some change is desirable, and 



