Ill] GROWTH AND CATALYTIC ACTION 131 



occur in the organism, part of whose energies are devoted to the 

 continual bringing-up of fresh supplies. 



Catalytic action occurs when some substance, often in very 

 minute quantity, is present, and by its presence produces or 

 accelerates an action, by opening " a way round," without 

 the catalytic agent itself being diminished or used up*. 

 Here the velocity curve, though quickened, is not necessarily 

 altered in form, for gradually the law of mass exerts its 

 effect and the rate of the reaction gradually diminishes. But 

 in certain cases we have the very remarkable phenomenon that 

 a body acting as a catalyser is necessarily formed as a product, 

 or bye-product, of the main reaction, and in such a case as this 

 the reaction-velocity will tend to be steadily accelerated. Instead 

 of dwind ing away, the reaction will continue with an ever- 

 increasing velocity : always subject to the reservation that limiting 

 conditions will in time make themselves felt, such as a failure of 

 some necessary ingredient, or a development of some substance 

 which shall antagonise or finally destroy the original reaction. 

 Such an action as this we have learned, from Ostwald, to describe 

 as "autocatalysis." Now we know that certain products of 

 protoplasmic metabolism, such as the enzymes, are very powerful 

 catalysers, and we are entitled to speak of an autocatalytic action 

 on the part of protoplasm itself. This catalytic activity of pro- 

 toplasm is a very important phenomenon. As Blackman says, 

 in the address already quoted, the botanists (or the zoologists) 

 "call it groivth, attribute it to a specific power of protoplasm for 

 assimilation, and leave it alone as a fundamental phenomenon; 

 but they are much concerned as to the distribution of new growth 

 in innumerable specifically distinct forms." While the chemist, on 

 the other hand, recognises it as a familiar phenomenon, and refers it 

 to the same category as his other known examples of autocatalysis. 



* Such phenomena come precisely under the head of what Bacon called 

 Instances of Magic : ' By which I mean those wherein the material or efficient 

 cause is scanty and small as compared with the work or effect produced ; so that 

 even when they are common, they seem like miracles, some at first iight, others 

 even after attentive consideration. These magical effects are brought about in 

 three ways... [of which one isj by excitation or invitation in another body, as in 

 the magnet which excites numberless needles without losing any of its virtue, or 

 in yeast and such-like." Nov. Org., cap. li. 



9—2 



