CHEMICAL CHARACTERS OF CELL 49 



mention has just been made; states it as his opinion 

 that "the irritability peculiar to this cell species 

 can be thus reduced to a sum of perfectly well- 

 defined tactisms " (the cell in question is the Tactisms 

 antherozoid of a fern). He proceeds : " After this 

 nothing remains of the pretended spontaneity of 

 movement in living bodies. An observer conversant 

 with the results of all these experiments in tactisms 

 knows that the movements he observes in living 

 bodies through the microscope are due to the colloid 

 and chemical reactions of the mobile beings and 

 the medium." This will seem to most readers of 

 Le Dantec's book a sufficiently wide deduction to 

 have been drawn from the comparatively few facts 

 brought forward. But let that pass. The quota- 

 tions just given make it abundantly clear that in 

 the author's opinion, and he may be taken as the 

 spokesman of a certain school of opinion, there is 

 no such thing as spontaneous or voluntary move- 

 ment, but all movement is in the nature of a 

 chemical or physical or chemico-physical reaction, 

 and that, although we may be wholly ignorant of 

 how this takes place, we may be quite sure, from 

 what we know of the behaviour of f ern-antherozoids 

 and the like, that it does take place. With this 

 summary of the views under consideration we may 

 now return to the writer's first example. What 



made the stone move? It moved because some 



D 



