Inheritance of Acquired Characters 229 



derer and their legs thinner. The horns, antlers, and pro- 

 tuberances that many of these animals possess are the results 

 of their butting each other when angered. 



" The long neck and the form of the giraffe offer a curious 

 case. We know that the giraffe is the tallest of all animals. 

 It inhabits the centre of Africa, living in those localities 

 where the earth is nearly always dry and without herbage. 

 It is obliged to browse on the foliage of trees, and this leads 

 to its stretching continually upwards. As a result of this 

 habit, carried on for a long time, in all the individuals of the 

 race, the anterior limbs have become longer than the pos- 

 terior, and its neck has also lengthened, so that the giraffe 

 without rising on its hind-legs stretches up its neck and can 

 reach to the height of six metres." 



The curved claws of the carnivora have arisen from the 

 necessity of grasping their prey. The power of retracting 

 the claws has also been acquired by the effort to draw them 

 in when running over hard ground. The abdominal pouch 

 of the kangaroo, in which the young are carried, opens an- 

 teriorly, and this has led to the animal standing erect so that 

 its young are not injured. In consequence, the fore-legs 

 have become shorter through disuse, and the hind-legs have 

 become stronger through use. The tail, which is also used as 

 a support, has become enormously thick at its base. 



The sloth has been compelled to seek refuge in the trees, 

 and has taken up its abode permanently there, feeding on 

 leaves. Its movements are limited to those involved in 

 crawling along the limbs in order to reach the leaves. After 

 feeding it remains inactive and sluggish, these habits being 

 provoked by the heat of the climate. The results of its mode 

 of life have been to cause the arms to become elongated due 

 to the habit of the sloth of grasping the limbs of the tree ; 

 the claws of the fingers and toes have also become long and 

 hooked in order to retain their hold. The digits that do not 

 make any individual movements have lost the power to do 



