138 SCIENCE PROGRESS 



things " as to admit a more or less mysterious extra-mechanical agency in all life. 

 It seems simpler and more coherent to admit the vitalist contention that in 

 consciousness, or mind, the extra-mechanical factor in life fully reveals itself. 



Of course the vitalist has still to face the possibility of a final resolution of 

 mind into physico-chemico terms. In any case his position is strengthened if he 

 can discover in any organic processes, such as embryogenesis, that are not 

 usually considered to involve consciousness, results that can be definitely placed 

 outside the scope of physics and chemistry acting alone. A fundamental difficulty 

 at once bars the way to this strategical position. Our experience is far too 

 limited to assign any limit to physico-chemico possibilities. Driesch suggests, in 

 his Problem of Individuality, that a machine may be defined as a given specific 

 combination of specific chemical and physical agencies. He argues that when 

 Hydra grows a new head after decapitation, or when sections of planarians 

 regenerate the whole animal, the mechanistic explanation does not suffice, because 

 a machine is a specific arrangement of parts, and this is altered if a part be 

 removed. Such an argument obviously lays its emphasis on the fixed arrange- 

 ment of rigid parts characteristic of human-made machines. It emphasises the 

 element of "machinery "in the ordinary or engineering usage of the term. Loeb 

 ascribes regeneration to the restriction placed on the flow of circulating bodies by 

 the isolation of parts. " We shall see that growth takes place in certain cells 

 when certain substances in the circulation can collect there. The mysterious 

 influence of the whole on these parts consists often merely of the fact that the 

 circulating specific or non-specific substances — we cannot yet decide which — will 

 on the whole be attracted by certain spots and that this will prevent them from 

 acting on other parts of the organism. If such parts are isolated the substances can 

 no longer flow away from these parts and the parts will begin to grow." This directs 

 attention to the enormous possibilities of the chemical element in mechanism. 

 " Machinery" plus chemical growth stimulators or producers, if lines of flow or 

 supply be supposed to be given, need not necessarily be put out of action by the 

 removal of parts, so long as the mechanism provided is equal to the task of 

 restoration. Driesch refers to the development of the ovary from the Anlage — 

 one cell producing a number of cells substantially similar to itself. "Machinery" 

 would hardly be capable of such achievement, but can the same be said of a 

 "constellation" of mobile chemical substances? A mother cell could give, it is 

 quite conceivable, to many daughter cells a sample of each of her enzymes or of 

 whatever chemical substances her mechanism might contain. The realisation 

 of the enormous potentiality for mechanistic organisation involved in the chemical 

 process or in a connected system of mobile chemical substances prevents any safe 

 declaration that certain results must be outside the purely mechanistic scope. 

 Our own utilisation of mechanism in our human-made machinery is too limited to 

 enable us to set any limit to Nature's powers. Our knowledge of Nature's 

 methods is insufficient for any assertion regarding their limits to be made. 

 Research continues to discover new mechanisms and new possibilities of mechanism 

 so rapidly and continuously that there must be an element of dogmatism in all 

 attempts to occupy a strategic position with respect to all non-conscious processes 

 by roundly stating that they fall outside purely mechanistic possibility. 



It may be possible, by moving upwards into psychology or into animal 

 behaviour, to show that the extra-mechanical factor in the organism is explicitly 

 displayed in consciousness or in animal activity. It may be possible to come 

 down on the mechanico-vitalistic controversy with a decision drawn from 

 philosophy. It does not yet seem possible, by a definite conclusion within the 





