152 , Traces of Unity, &c. 



There are also many familiar facts which serve to 

 show that artificial light and heat have a like influence 

 upon plants and animals. Flowers wake through 

 the night in a well-lit room. Many annual plants 

 become perennial under the fostering shelter of the hot- 

 house. An animal that hybernates ordinarily wakes 

 through the winter in cosy quarters, and sleeps through 

 the summer in the contrary case. These facts, and many 

 others like them, are of great 'interest in themselves, but 

 they are of greater interest as confirming the conclusion 

 already arrived at respecting the relations of natural 

 light and heat to life, for if this vivifying power belongs 

 to artificial light and heat it. is impossible to conceive 

 that it does not belong also to natural light and heat. 



In a word, the life of plants and animals is so affected 

 by climate and season as to more than justify the notion, 

 not only that light and heat have a vivifying power, but 

 also that vital force and physical force are united in the 

 very closest manner. 



