SUMMARY OF l PHILOSOPHIE ZOOLOGIQUE.' 295 



heat, light, and moisture, and to the preponderance over 

 others which certain of the vital functions attain to." 



Lamarck is led into the statement that plants have 

 neither actions nor habits, by his theories about the 

 nervous system and the brain. Plain matter-of-fact 

 people will prefer the view taken by Buffon, Dr. Dar- 

 win, and, more recently, by Mr. Francis Darwin, that 

 there is no radical difference between plants and 

 animals. 



" The differences between well-nourished and ill- 

 nourished plants become little by little very noticeable. 

 If individuals, whether animal or vegetable, are con- 

 tinually ill-fed and exposed to hardships for several 

 generations, their organization becomes eventually 

 modified, and the modification is transmitted until a 

 race is formed which is quite distinct from those 

 descendants of the common parent stock which have 

 been placed in favourable circumstances.* In a dry 

 spring the meagre and stunted herbage seeds early. 

 When, on the other hand, the spring is warm but with 

 occasional days of rain, there is an excellent hay-crop. 

 If, however, any cause perpetuates unfavourable cir- 

 cumstances, plants will vary correspondingly, first in 

 appearance and general conditions, and then in several 

 particulars of their actual character, certain organs 

 having received more development than others, these 

 differences will in the course of time become hereditary.f 



"Nature changes a plant or animal's surroundings 

 gradually man sometimes does so suddenly. All 

 botanists know that plants vary so greatly under 



* Phil. Zool.,' torn. i. p. 225. f Page 226. 



