202 EIGHTEENTH CENTURY. pt. in. 



like ourselves, they have a heart, lungs, bones, and muscles, 

 and their legs possess muscles and nerves like those of a 

 man ; yet Spallanzani cut off the tail and legs of one sala- 

 mander six times in succession, and in another case. Bonnet 

 cut them off eight times, and they grew again. Bonnet even 

 took out the right eye of a newt, or eft, and in eight months 

 another eye had grown in its place. These experiments were 

 very startling, for they showed that the life of the lower 

 animals does not depend on a particular part of the body so 

 much as it does in ourselves and in the higher animals. If 

 you cut off the head of a man or an ox, they die, or if you 

 cut off a leg, it never grows again ; but these experiments 

 proved that the worm and the snail live and grow new heads 

 and limbs, and that the more simple an animal is, the more 

 power it has to live and grow after it is cut in pieces. 



These discoveries led Bonnet to make a suggestion which 

 I want you to remember, because we shall have to speak of 

 it by-and-bye. He asked whether it was not Hkely that 

 there was a gradual development or complication of the 

 parts of the body as you ascend from the lowest plant up to 

 the highest animal, so that the body of a worm, for example, 

 could do all the work necessary to keep it alive and to make 

 it grow, without the help of its head, and a lizard could in 

 the same way make a new leg without much difficulty. But 

 as the machinery grew more and more complicated this would 

 not be so easy, till at last it would become impossible in the 

 higher animals, just as in a complicated machine one broken 

 wheel will upset the whole working. Bonnet wrote a book 

 called * The Contemplation of Nature,' in which he dwelt 

 upon this subject, and tried to trace out how animal forms 

 had become gradually higher and higher, till they had arrived 

 at man. We shall see by-and-by how this idea occurred also 



