226 EVOLUTION, OLD AND NEW. 



the tadpole, which acquires legs and lungs when he 

 wants them, and loses his tail when it is no longer of 

 service to him. 



" Fifthly, from their first rudiment or primordium to 

 the termination of their lives, all animals undergo 

 perpetual transformations ; ivhich are in part produced 

 ly their own exertions in consequence of their desires and 

 aversions, of their pleasures and their pains, or of irrita- 

 tions or of associations ; and many of these acquired 

 forms or propensities are transmitted to their posterity. 



" As air and water are supplied to animals in sufficient 

 profusion, the three great objects of desire which have 

 changed the forms of many animals by their desires to 

 gratify them are those of lust, hunger, and security. 

 A great want of one part of the animal world has con- 

 sisted in the desire of the exclusive possession of the 

 females ; and these have acquired weapons to combat 

 each other for this purpose, as the very thick, shield- 

 like, horny skin on the shoulder of the boar is a 

 defence only against animals of his own species who 

 strike obliquely upwards, nor are his tusks for other 

 purposes except to defend himself, as he is not naturally 

 a carnivorous animal. So the horns of the stag are 

 anarp to offend his adversary, but are branched for the 

 purpose of parrying or receiving the thrust of horns 

 similar to his own, and have therefore been formed for 

 the purpose of combating other stags, for the exclusive 

 possession of the females ; who are observed like the 

 ladies in the times of chivalry to attend the car of the 

 victor. 



" The birds which do not carry food to their young, 



