96 ON PLANTS. 



soul, of plants occupied the minds of many who wrote about 

 them, and attempts were made to determine in what part 

 or parts of the plant the soul resided. The general opinion 

 was that the soul of a plant resided in the " heart " or pith, 

 and, as late as the sixteenth century, Csesalpinus seriously 

 considered this subject. After deciding that a very suitable 

 position for the soul of a plant is in the middle of the part 

 where the stem starts from the root, he argued that a soul 

 existed even in the axil of each leaf, and finally concluded 

 that the soul of a plant was veluti in omnes partes distrihutum, 

 or distributed as it were to all parts of the plant.* 



The statement that plants are affected in some way by 

 external influences! is not clear, but the context suggests 

 that the effects of cold and heat on the plants were in 

 Aristotle's mind. 



Eespecting the nutrition of plants, he says that they 

 obtain food by means of their roots,! which he compares 

 with the mouth of an animal, § and with the blood-vessels 

 of the umbilical cord.|| Their food, he says, must be liquid 

 and, although they seem to be nourished by one substance 

 only, viz., water, yet they are nourished by more than one 

 substance, for earth is in combination with the water. 11 

 Plants, he says, obtain their food from the earth in a digested 

 state, wherefore waste matters are not produced in plants, 

 which use the earth and its heat in place of a stomach.** 



Aristotle did not know anything about the nutritive 

 importance of the leaves and other green parts, but his 

 statement about the complex nature of the food of plants is 

 correct as far as it goes. The most remarkable parts of his 

 statements about the nutrition of plants are, however, those 

 relating to the function of the soil and the consequent 

 absence of waste matters in plants. He is reasoning, as he 

 often does, by analogy with animals. The food taken up by 

 the roots required no elaboration so as to separate the use- 

 ful from the waste parts ; this process had been effected, so 

 Aristotle believed, by means of the soil and its heat. The 

 plants received a food which corresponded with that which, 

 in animals, passed from the stomach and small intestines 

 into the blood. No waste products, so Aristotle says, were 

 formed. This view was held for many centuries after 



■^ De Plantis, Florence, 1583, p. 10. f De Anima, ii. c. 12, 424a. 



I P. A. iv. c. 7, 683&. § De Javent. et Scnect. c. i, 468a-. 



II G. A. ii. c. 7, 7456. II De Gener. et Corr. ii. c. 8, 335fl. 



*- P. A. ii. c. 3, 650a, ii. c. 10, 655&. 



