SYMBIOSIS 23 



only local attachment can constitute a case of either symbiosis 

 or parasitism. They seem to be obsessed by definitions. 



Wer will was Lebendigs erkennen und beschreiben 



Sucht erst den Geist heraus zu treiben, 



Dann hat er die Theile in seiner Hand, 



Fehlt, Leider ! nur das geistige Band. 



It is well to investigate the mechanical streaming of food 

 in Convoluta from the coloured to the colourless (animal) cells. 

 But it is equally important to recognise that this is due to the 

 bond of symbiosis, and that it is the identical bond which 

 unites all organisms. 



As I have now drawn a distinction between local 

 (domestic) symbiosis and more specialised biological (bio- 

 economic) symbiosis, it may be as well before proceeding with 

 the study of Convoluta to dwell a little longer on a considera- 

 tion of the former, particularly with a view to elucidate more 

 fully the universal import of symbiosis. 



Prof. Keeble's work on plant-animals has already stimu- 

 lated a practical botanist, Mr. H. C. Davidson, to reconsider 

 the subject of the nature of plants in the light of symbiosis. 

 In a contribution to the Contemporary Review for September, 

 1913, he submits that a plant is not a single individual, but a 

 community of individuals, gathered together in a state of 

 symbiosis. The associated individuals he proposes to call 

 " plantagens." Their association is for the common good, and 

 when thus united higher results are produced than when the 

 partners start growth on their own account and irrespective 

 of the common good. 



Symbiosis is generally defined as a physiological partner- 

 ship between individuals of different species. But, says Mr. 

 Davidson : 



The possibility that it may occur between individuals of the same 

 species, though a much more likely phenomenon, seems to have been over- 

 looked. Every plant above the simple cell is not, as is generally supposed, 

 an individual entity, but in reality a group or family of individuals 

 associated within a common protecting envelope, the bark, and upon 

 a common root for the common good. . . Each of these individuals 



