62 SPECIES NOT 



CHAPTER IV. 



THE third chapter in Mr. Darwin's book is 

 occupied by the consideration of "Struggle for 

 Existence/' with its bearing upon "natural se- 

 lection, which is dealt with in the fourth. 



By the "struggle for existence," Mr. Darwin 

 considers that "any variation, however slight, and 

 from whatever cause proceeding, if it be in any 

 way profitable to an individual of any species in 

 its infinitely complex relations to other organic 

 beings, and to external nature, will tend to the 

 preservation of that individual, and will generally 

 be inherited by its offspring." 



There can be no doubt about the "struggle 

 for existence." From man to the lowest animal 

 the product of life is necessary to support life. 

 It is a part of the great and inscrutable scheme 

 of nature that it should be so. A vast number 

 of animals subsist upon each other, while the 

 rest live upon plants, and we see a beautiful 

 gradation in the mode of preparing food for the 

 higher animals. Every thing necessary for man's 

 existence is taken out of the earth and air by 

 the family of grasses, but he would die if fed 

 upon grass alone. Therefore it is necessary there 

 should be intermediate forms, and the ox and 

 the sheep convert the grass into beef and mutton, 

 which is the principal part of human food. Is 



