THE LIFE VARIES AS THE CORRESPONDENCE. 85 



that the degree of life varies with the degree of correspond- 

 ence. For if the lengthened existence of a tree be looked 

 upon as tantamount to a considerable degree of life ; then it 

 must be admitted that its lengthened display of correspond- 

 ences is tantamount to a considerable degree of correspond- 

 ence. If otherwise it be held, that notwithstanding its much 

 shorter existence, a dog must rank above a tortoise in degree 

 of life, because of its superior activity ; then it is implied that 

 its life is higher, because its simultaneous and successive 

 changes are more complex and more rapid — because the 

 correspondence is greater. And since we regard as the high- 

 est life, that which, like our own, shows great complexity in 

 the correspondences, great rapidity in the succession of them, 

 and great length in the series of them ; the equivalence 

 between degree of life and degree of correspondence, is un- 

 questionable. 



§ 33. In farther elucidation of this general truth, and 

 especially in explanation of the irregularities just referred to, 

 it requires to be observed, that as the life becomes higher 

 the environment itself becomes more complex. Though, 

 literally, the environment means all surrounding space with 

 the coexistences and sequences contained in it ; yet, practi- 

 cally, it often means but a small part of this. The environ- 

 ment of an entozoon, can scarcely be said to extend beyond 

 the body of the animal in which the entozoon lives. That of 

 a fresh-water alga is, virtually, limited to the ditch inhab- 

 ited by the alga. And understanding the term in this re- 

 stricted sense, we shall see that the superior organisms 

 inhabit the more complicated environments. 



Thus, contrasted with that found on land, the lower life is 

 that found in the sea ; and it has the simpler environment. 

 Marine creatures are affected by a smaller number of co- 

 existences and sequences than terrestrial ones. Beinp- very 

 nearly of the same specific gravity as the surrounding 

 medium, they have to contend with less various mechanical 



