CHAP, ii.] from Cesalpino to Linnaeus. 43 



the understanding, are treated as really existent substances, as 

 active forces, under the name of principles; final causes 

 appear side by side with efficient; the organs and functions of the 

 organism exist either alicujus gratia or merely ob necessitatem ; 

 the whole account is controlled by a teleology, the influence of 

 which is the more pernicious because the purposes assumed 

 are supposed to be acknowledged and self-evident, plants and 

 vegetation being conceived of as in every respect an imperfect 

 imitation of the animal kingdom. It was moreover a neces- 

 sary consequence of the treatment of his material adopted by 

 Cesalpino, that his ignorance of the sexuality of plants and of 

 the use of leaves as organs of nutrition led him to false and 

 mischievous conclusions ; this defect of knowledge would have 

 been of less importance in a purely morphological consideration 

 of plants, as we shall see presently in Jung ; but with Cesal- 

 pino morphological and physiological considerations are so 

 mixed up together, that a mistake in the one direction neces- 

 sarily involved mistakes in the other. 



These remarks on Cesalpino's method may be illustrated by 

 some examples tending to show how closely he attaches himself 

 to Aristotle, and how certain Aristotelian conceptions, the 

 origin of which has not been sufficiently regarded, passed 

 through him into later botanical speculation. We shall recur 

 in the History of Physiology to Cesalpino's views on nutrition, 

 and to his rejection of the doctrine of sexuality in plants. 



'As the nature of plants,' so begins Cesalpino's book, 

 ' possesses only that kind of soul by which they are nourished, 

 grow, and produce their like, and they are therefore without 

 sensation and motion in which the nature of animals consists, 

 plants have accordingly need of a much smaller apparatus of 

 organs than animals.' This idea reappears again and again in 

 the history of botany, and the anatomists and physiologists of 

 the 1 8th century were never weary of dilating on the simplicity 

 of the structure of plants and of the functions of their organs. 

 ' But since,' continues Cesalpino, ' the function of the nutritive 



