Relations of Classes. 8 1 



is so linked with that enjoyment which the world in 

 all its relations secures to his higher, intellectual, 

 and moral nature, that it becomes as difficult to 

 separate one source of enjoyment from the other 

 and assign the exact proportion to each nature, as it 

 is to separate those natures from each other in their 

 wonderful blending in the constitution of man. 

 There is, therefore, a certain distinctness gained 

 when treating of the adaptations of the lower ani- 

 mals to the world, which it is impossible to secure 

 when treating of the complex being, man. In the 

 lower animals we find nothing beyond adaptations 

 to this world. They are physical beings only. 

 There is nothing to be eliminated. On the other 

 hand, we can learn the completeness of their adapta- 

 tions only by observation. For our experience is 

 rendered an imperfect standard on account of this 

 very complexity of our nature. 



We propose in the remainder of this lecture to 

 treat mainly of those relationships by which whole 

 classes of animals are fitted to the world, and re- 

 serve for a distinct chapter many of those special 

 adaptations by which particular species or varieties 

 are fitted for unusual conditions. But in treating 

 of the adaptations of animals to the world, we must 

 include their general relationships to each other, 

 because their very existence often depends upon 

 surh relationships. 



The waters are the home of a large proportion 

 of the animal kingdom. In them we find a vast 

 range of animal life beyond the reach of ordinary 



