Page:Mind (New Series) Volume 9.djvu/338

324 CHABLES S. MYERS : gists have only been too eager to console themselves with the working of a vis or ens vitalis, where failure had other- wise stared them in the face. Instead of endeavouring to improve the sensitiveness and the accuracy of their instru- ments or to reduce the complexity of experimental conditions, they have chosen the easier course of attributing all their troubles to the action of some force which lies confessedly far beyond their comprehension. Year by year this practice has continued unchanged, although year by year the intrusion of mechanism into physiology becomes increasingly evident. Perhaps of all phenomena, formerly deemed " vital " and now described in physical language, ferment-action is the most striking. (This will receive closer examination almost immediately.) Another example, where similar but less marked progress has been made, is the process of absorp- tion. For it seems fairly evident, much as has yet to be learnt concerning the rates and general nature of osmosis and dialysis, that Heidenhain's "physiological osmotic action " is a process of a mixed quasi-chemical and physical nature and, in this respect only, differs from the purely " physical osmotic action ". The state of continued chemical instability of the living substance, whereby the composition of the living membrane and the consequent osmotic changes are never constant for two successive moments ; the influ- ence of metabolic processes on the composition of the fluid transferred, so that large quantities of a given substance may conceivably be built up into more complex bodies and afterwards reduced to their former simplicity on the other side of the living membrane ; all these and similar obscure factors are likely in the near future to be determined. Meanwhile certain writers, bearing in mind that osmosis and filtration as at present understood are incapable of offering a satisfactory explanation of the phenomena in question, are justified in describing these processes as being in a sense the servants rather than the masters of proto- plasmic activity (23). It cannot be too strongly insisted, however, that "everything is specific which we cannot explain, and dynamic is the explanation of all which we do not understand : the terms having been invented merely for the purpose of concealing ignorance by the application of learned epithets "- 1 Physiologists have long been acquainted with a class of substances which appear to be endowed (under suitable conditions) with almost unwearying chemical activity; and, 1 Surely these words of Justus v. Liebig compel the famous chemist and vitalist to be hoist with his own petard.