34 The Unity of the Organisin 



made to interpret the organism in accordance with the 

 theory which denies its individuahty. Our first instance will 

 be taken from botany. But before proceeding with this, it 

 is desirable to point out that some of the most distinguished 

 botanists, especially physiological botanists, have recog- 

 nized the unity of the plant without stint or cavil. 



We appeal to only one of the botanists of this class, 

 PfefFer. In The Physiology of Plants, he says : "The in- 

 timate correlation of the entire vital mechanism renders it 

 probable that every excitation exercises some effect upon 

 other manifestations of irritability, even though this effect 

 may not always be directly perceptible."^ 



Again : "In the plant community the activity of every 

 cell and of every organ is subservient to the common weal, 

 and may, when necessary, be modified as already indicated 

 so as to fulfill the changed requirements of the whole. "^ 



It is true, I believe, that the mode of thought about plants 

 illustrated b}^ these quotations is characteristic of botanists 

 in whom observation and speculation maintain a due bal- 

 ance; botanists with whom, in other words, speculation has 

 not got the upper hand of obsei'vation. 



It is highly significant that one of the most pronounced 

 and, so far as I have discovered, earliest authors to specu- 

 late on the non-individuality of the plant was Schleiden, one 

 of the fathers of the cell-theory. In his famous Contribu- 

 tion to Phytogenesis we read in a discussion of the individu- 

 ality of plants : "In the strictest sense of the word, only the 

 separate cell deserves to be called an individual."^ Elabor- 

 ating this notion, "The woody stem," he tells us, "cannot 

 come under the idea of a plant." And further: "It neces- 

 sarily pertains to the notion of a plant, that it produces 

 foliaceous organs on its stem, yet there is no tree which 

 produces leaves."^ This last statement sounds, the author 

 admits, rather paradoxical, but, he contended rightly 

 enough, the mere circumstance of its sounding paradoxical 



