466 Theory of the Nutrition [Book hi. 



Mariotte concluded that the primary sap finds its way into 

 the plant through the leaves as well as through the roots from 

 the fact, that if a branch is taken from a tree, and one of its 

 smaller branches kept in water, another will remain fresh for 

 some days; the conclusion was not quite justified, as the 

 future showed. His remarks on the necessity of sunlight 

 to nutrition, on the ripening of fruit, and other matters, rests 

 on very imperfect experience and need not be noticed. 



The characteristic and the important point in Mariotte's 

 theory of nutrition is the marked contrast between his point of 

 view in natural science and the Aristotelian and scholastic 

 doctrines still widely diffused, and thus he is led to declare 

 war also against Aristotle's vegetable soul. He connects his 

 remarks on this point with a fact which excites his astonish- 

 ment, namely that every species of plant reproduces its proper- 

 ties so exactly ; no explanation of this fact, he says, is gained 

 by the assumption of a vegetable soul, of which no one knows 

 what it is. He declares as decidedly against the theory of 

 evolution, also much in vogue in his day. In opposition to 

 the notion that all future generations are shut up one inside 

 another in the seeds of a plant, he thinks it much more 

 probable that the seeds only contain the essential substances, 

 and that their influence on the crude sap brings about the 

 successive formation of the rest of the constituents of the plant, 

 a view which we may still allow to be correct. He regards the 

 whole process of nutrition and life in plants as a play of phy- 

 sical forces, as the combination and separation of simple 

 substances, but he believes at the same time that he can 

 prove the commonly received doctrine of spontaneous gener- 

 ation to be a necessary conclusion from this view. On this 

 point he went wrong from want of sufficient and well-sifted 

 experience, for he regarded it as a proof of generatio spontanea 

 that numerous plants spring up from the soil thrown out from 

 ditches and swamps that have been laid dry. ' We may there- 

 fore suppose,' he says, ' that there are in the air, in the water, 



