orientation of the cells in relation to the center of gravity of the earth, the two phases undergo a shifting by means of which a change in the rate of reaction is brought about according to one of the ways given above. Since then I have looked through the literature on the function of the otoliths or statoliths, and have reached the conclusion that all writers who assert that the removal of the otoliths disturbs the geotropic orientation of animals have been victims of the same fallacy as myself. They have injured or removed the nerve endings. In the only case in which a removal of the otoliths without tearing or other injury of the nerve endings can be justifiably assumed, no disturbance of the orientation occurred.
While in my own work I have aimed to trace the complex reactions of animals to simpler reactions like those of plants and finally to physicochemical laws, the opposite tendency has lately been gaining influence. Some botanists, namely, Haberlandt, Nĕmec and F. Darwin, endeavor to show that the relatively simpler reactions of plants may be traced back to the more complex relations found in animals. Instead of deriving the tropic reactions of plants as directly as possible from the law of mass action (and other physico-chemical laws), they try to show that "sense organs" exist in the cells of plants and France even attributes to the latter a "soul" and an "intelligence." I believe that in order to be consistent, these writers ought to base the law of mass action upon the assumption of the existence of sense-organs, souls and intelligence in the molecules and ions. It is probably unnecessary to emphasize the fact that it is better for the progress of science to derive the more complex phenomena from simpler components than to do the contrary, namely, to try to explain the simpler by means of the more complex. For all "explanation" consists solely in the presentation of a phenomenon as an unequivocal function of the variables by which it is determined, and if in nature we find a function of two variables, it does not, in my opinion, tend toward progress to assert that this is a case of functions of more than two variables, without furnishing sufficient proof of this assertion.
These writers represent the geotropic reactions of plants by saying that in certain cells starch grains are present which serve the purpose of the otoliths in animals. These starch grains are believed to press upon the sense organs or nerve endings in the plant cells concerned and the pressure sense of the plant is then supposed to give rise to the geotropic curvature. I have no opposition to offer to the assumption that the starch grains change their position with a change in the position of the cells, and I am also willing to pass over for the present the view that the starch grains form one of the two phases in the cell. But I see no necessity for assuming besides this the existence of intracellular sense organs which perceive the pressure of the starch grains.