462 Theory of the Nutrition [BOOK in. 



plants ; but we are compensated for this by his making us 

 acquainted with everything fundamentally important and new 

 which could at that time be said on the chemistry of the food 

 of plants. Speaking of the ' elements ' or ' principles ' of plants, 

 Mariotte propounds three hypotheses. The first is, that there 

 are many immediate principles (principes grossiers et visibles, 

 evidently what we should call proximate constituents) in plants, 

 such as water, sulphur or oil, common salt, nitre, volatile salt or 

 ammonia, certain earths, etc. and that each of these immediate 

 constituents is a compound of three or four more simple prin- 

 ciples, which have united together into one body ; nitre for in- 

 stance has its ' phlegma ' or tasteless water, its ' spiritus,' its fixed 

 salt, and other things ; common salt in the same way has the 

 like constituents, and it may be assumed with much probability, 

 that these more simple principles also are compounds of parts 

 that differ among themselves, but are too small to be distin- 

 guished by any artificial means as to figure, or any other 

 characters. Having shown how certain principles unite together, 

 he goes on to say, that he is unwilling to ascribe to them any 

 sort of consciousness (connaissance) by which they seek to 

 unite together ; but he thinks that they are endowed with 

 a natural disposition to move towards one another, and to 

 unite closely as soon as they touch one another ; though it is 

 very difficult to define the nature of this disposition, it is enough 

 to know that there are many instances of such movements to 

 be found in nature ; thus heavy bodies move towards the 

 centre of the earth, and iron to the magnet ; nor are these 

 movements more difficult to conceive, than that of the planets 

 in their courses or of the sun round its axis, or that of the 

 heart in a living animal. With this first hypothesis Mariotte 

 places himself, in opposition to the Aristotelian doctrine with its 

 entelechies and final causes which prevailed at that time 

 among botanists and physiologists, upon the firm ground of 

 modern science with its atoms, and its assumption of necessarily 

 active forces of attraction. 



