CHAP, ii.] of Plants. Mariotte. 467 



and in the earth an infinite number of minute bodies so 

 fashioned that two or three uniting together may make the 

 beginning of a plant, and represent the seed of such a plant, if 

 they find a soil favourable to their growth. But it is not pro- 

 bable that this little complex body contains already all the 

 branches, leaves, fruits, and seeds of this plant, and still less 

 that this seed contains all the branches, leaves, flowers, etc., 

 which proceed ad infinitum from the first germination.' The 

 contrary he thinks is proved by the fact, that a rose-bush which 

 has lost its leaves in the winter may produce in the next year 

 nothing but leafy shoots from its flower buds, which shows that 

 the blossoms were not previously formed in those buds, and 

 that a similar conclusion is to be drawn from another fact, that 

 the seeds of one and the same fruit-tree or of a melon produce 

 descendants that differ from one another by variation ; here we 

 have an argument against the theory of evolution much more 

 to the purpose than the greater part of those w r hich were 

 alleged against it before Koelreuter obtained his hybrids. 



Other prejudices also of his day were opposed by Mariotte, 

 and on good grounds ; the medicinal effects, commonly known 

 as the 'virtutes' of plants, played an important part in the botany, 

 and still more in the medicine and chemistry of that time. He 

 rejects the old theory of heat and cold, moisture and dryness, 

 things supposed to be essentially immanent qualities of the 

 substance of plants and used to explain their medicinal effects, 

 and pointing to the fact, that poisonous plants grow in the same 

 soil as harmless ones and side by side with them, he concludes, 

 as he had before concluded, that different plants do not derive 

 their peculiar constituents immediately from the soil, but that 

 they form them themselves by separation and combination of 

 the common principles. Finally he declared against one of 

 the grossest errors which had come down from the piv\i<>us 

 century, the ' signatura plantarum,' which supposed that the 

 medicinal properties of plants could be deduced from their 

 external features, and especially from resemblances between 



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