468 Theory of the Nutrition [BOOK HI. 



their organs and the organs of the human body. Mariotte 

 insists that the medicinal properties of plants are to be ascer- 

 tained by trying them on sick people. 



Mariotte's letter, the most important parts of which have 

 here been given, presents us with a lively picture of the views 

 which prevailed in the second half of the zyth century re- 

 specting the life of plants ; it shows at the same time how an 

 eminent investigator of nature, adopting the principles of a 

 more modern philosophy and knowing how to make a skilful 

 use of the facts that were known to him, was led to oppose 

 antiquated error, the result of prepossessions and want of re- 

 flection. If we combine the views of Malpighi on the internal 

 economy of the plant, derived chiefly from its anatomy, with 

 the chemical and physical disquisitions of Mariotte, we have 

 an entirely new theory of the nutrition of plants, not only 

 antagonistic to the Aristotelian doctrine, but distinguished 

 from it by a much greater wealth of ideas and by more 

 sagacious combinations. 



These two men had in truth discovered all the principles of 

 vegetable life and nutrition, which could have been discovered 

 in the existing condition of phytotomy and chemistry; Mariotte 

 especially had succeeded in applying the very best that was to 

 be obtained from the uncertain chemical knowledge of his 

 day to the explanation of the phenomena of vegetation. 

 Chemistry was at that time beginning to set herself free from 

 the notions of the medical science, the iatro-chemistry of a 

 former age, only to throw herself into the arms of the theory 

 of the phlogiston ; and how little she could contribute to the 

 explanation of the processes of nutrition in plants, how little 

 the methods then in use were adapted to the examination of 

 organised bodies, may be learnt from a little book published 

 in 1676 and again in 1679, ' Memoires pour servir a 1'histoire 

 des plantes,' which appeared indeed in Dodart's name, but 

 which was compiled and approved by the body of members of 

 the Academy of Paris. It contains no results of investigation, 



