454 PHYSIOLOGY CHAP. 



It seems probable (if we may be permitted for a moment to 

 pass the bounds of positive knowledge) that subconscious psycho- 

 physical processes play over the whole of the vast area of the 

 living world. There is nothing unreasonable in the idea that all 

 the complex functions by which living organisms plants and 

 animals are differentiated from the inorganic aggregates of non- 

 living Nature aiv accompanied by, or have the character of, sub- 

 conscious psycho-physical processes. The sensibility of plants, 

 admitted even by the older botanists, must not be interpreted in a 

 metaphorical sense as a mere increase of excitability, but in a true 

 psychological sense as the capacity of feeling elementary sensa- 

 tions, fruiu which subconscious states arise. In all plants- as 

 Tangl first observed in germinating seeds the living elements, 

 from the simplest cellular groups to the most complex of the 

 higher vegetables, are conneei.-d by the protoplasmic filaments, or 

 plasmodesmata which recall the fibrils of the animal nervous 

 system. By means of this elaborate system of protoplasmic fila- 

 ments some plants are capable of responsive and protective acts, 

 similar to those observed \\ben the lower animals react to external 

 stimuli. This capacity for reaction is for the most part diffused 

 throughout the vegetable protoplasm ; in other cases it is localised 

 more particularly in certain parts (leaves, roots) ; in others again 

 in special organs, which by their peculiar structure recall the 

 sense-organs of animals as was pointed out by Noll (1896), and 

 described in more detail by G. Haberlandt and Nemec (1900). 



In many, especially among the higher plants, special organs 

 have been recognised morphologically and experimentally that are 

 able to react to mechanical stimuli, like the tactile organs of 

 animals ; special organs on which depend the positive geotaxis of 

 the roots, the negative geotaxis of the stems, the transverse geo- 

 taxis of the leaves, similar to the organs of orientation in animals ; 

 lastly, special organs adapted to react to the light stimulus, on 

 which heliotaxis depends, and which by their complicated structure 

 recall the visual organs of animals. 



Granting all this, it seems to us without admitting the 

 exaggerated pretensions of Haberlandt that it is not unreason- 

 able to admit that plants exhibit rudimentary phenomena of 

 psychical life ; in other words, that the various forms of sensibility 

 in vegetables are the expression of specific psycho-physical pro- 

 perties inherent in the complex structure of living protoplasm. 

 But remembering that plants, like the lower animals, are destitute 

 of central organs homologous to the nervous system of the higher 

 animals, there can be no doubt that they have no conscious sub- 

 jective phenomena ; i.e. that in them, as in the lower animals, all 

 forms of association and of psychical synthesis, on which the 

 multiple and graduated forms of conscious life depend, are absent. 



We may conclude that the unconscious extends into the lower 



