52 Artificial Systems and Terminology of Organs [BOOK i. 



necessarily be mixed up together 1 ; the difficulty arises from our 

 uncertainty as to the rules by which we should determine the 

 resemblances of the genera. While there are two chief parts 

 in plants, the root and the shoot, we cannot, as it seems, deter- 

 mine the genera and species from the likeness or unlikeness 

 either of the one or of the other ; for if we make a genus of 

 those plants which have a round root, as the turnip, Aristolo- 

 chia, Cyclamen, Arum, we separate generically things which 

 agree together in a high degree, as rape and radish which 

 agree with the turnip, and the long Aristolochia which agrees 

 with the round, while at the same time we unite things most 

 dissimilar, for the Cyclamen and the turnip are in every other 

 respect of a quite different nature ; the same is the case with 

 divisions which rest merely on differences in the. leaves and 

 flowers. 



In pursuing these reflections, which have the conception of 

 species chiefly in view, he arrives at the following proposition : 

 That according to the law of nature like always produces like, 

 and that which is of the same species with itself. 



All that Cesalpino says on systematic arrangement shows 

 that he was perfectly clear in his own mind with regard to the 

 distinction between a division on subjective grounds, and one 

 that respects the inner nature of plants themselves, and that he 

 accepted the latter as the only true one. He says, for instance, 

 in the next chapter : ' We seek out similarities and dissimilari- 

 ties of form, in which the essence ('substantia') of plants consists, 

 but not of things which are merely accidents of them ('quae 

 accidunt ipsis ').' Medicinal virtues and other useful qualities 

 are, he says, just such accidents. Here we see the path opened, 

 along which all scientific arrangement must proceed, if it is to 

 exhibit real natural affinities ; but at the same time there is a 

 warning already of the error which beset systematic botany up 



1 These words are quoted by Linnaeus in the 'Philosophia Botanica,' 

 par. 159. 



