PLANTS AND ANIMALS 217 



Profound changes in the environment event- 

 ually bring about changes in structure; but 

 they follow so slowly that rudimentary or- 

 gans and various vestigial structures reveal 

 the true affinities where all other characters 

 fail. 



In all serious attempts to fully distinguish 

 the two kingdoms, so far as they have come 

 to my notice, the characters selected have 

 been essentially physiological, and not struc- 

 tural. Some of the most noted of these maj^ 

 be briefly mentioned. Linnaeus leads with his 

 classical aphorism : ''Lapides crescunt, veget- 

 ahilia crescunt et vivunt, animalia crescunt, 

 vivunt et sentient,'' with which he opened his 

 work on philosophical botany in 1751. 

 Cuvier, in the second edition of his "Regne 

 animal," issued in 1828. elaborated four 

 reasons for the ''division of organized beings 

 into animals and vegetables:" viz., the pos- 

 session by animals of (1) organs foringestion 

 of food, (2) circulatory system, (3) nitrog- 

 enous structure and (4) true respiration, of 

 which the first seemed to him most important, 

 and did, indeed, survive the longest. The 

 distinction advocated by Dangeard (1887), 

 Minot (1895), and others, that only animals 

 are capable of receiving solid food into the 

 body, may be considered the latest phase of 



