54 THE FUNCTIONS OF LIFE. 



ments.* But as the discussion of these and 

 other topics relating to the plans and designs of 

 nature in the formation of organic beings re- 

 quires a previous acquaintance with the details 

 of comparative anatomy and physiology, I shall 

 defer all further observations respecting them 

 till I have finished the review I propose to take 

 of the several structures and functions of the 

 animal and vegetable economy. There are, 

 however, some views that have been entertained 

 respecting the procedure of nature in the forma- 

 tion of the different races of animals, which it will 

 be proper to notice in this place, as they will 

 occasionally be referred to when the facts that 

 more particularly illustrate and support them 

 come to be noticed. 



An hypothesis has been advanced that the 

 original creation of species has been successive, 

 and took place in the order of their relative com- 

 plexity of structure ; that the standard types 

 have arisen the one from the other ; that each 

 succeeding form was an improvement upon the 

 preceding, and followed in a certain order of 

 developement, according to a regular plan 

 traced by the great Author of the universe for 

 bestowing perfection on his works. This grada- 



* Mr. M'Leay is the author of this ingenious theory, which 

 he has developed in his " Horcs. Entomologies" and which 

 appears to be verified to a great extent by the modern disco- 

 veries in comparative anatomy. 



