HEA.T EQUIVALENT OF NUTRIENTS OF FOOD. 607 



lose is soluble in coiioeutrated sulphuric acid, and yields dextrin on 

 the addition of water, the action of dilute acid on cellulose might be 

 explained by the formation of cellulose-sulphuric acid as an intermediate 

 product and the subsequent decomposition of this by water. This is, 

 however, evidently incorrect. The formation of cellulose-sulphuric acid 

 takes place only when water is not present. Thus the change of cellu- 

 lose to sugar in dilute solutions can not be due to a cellulose-sulphuric 

 acid. 



The same is true also of the inversion of sugar by dilute acid, the 

 change of starch to sugar, and the splitting up of ethers, glycerids, etc., 

 due to the same oause. There is also this fact in addition: these reac- 

 tions take place under the influence of all acids, but the cellulose and 

 starch compounds of most acids are not known and in all probability 

 do not exist. The action of the acid on the sugar is just like that of 

 invertin, its action on starch the same as that of diastase. The action 

 of acid on sugar, starch, and cellulose is just as much catalytic as the 

 action of any ferment. Molecular vibrations are produced in these sub- 

 stances by sulphuric, hydrochloric, or oxalic acid just as much as they 

 are in oleic acid by nitrous acid. Catalytic reactions can thus be brought 

 about by the most varied substances, which do not of necessity produce 

 the slightest chemical effect, and many such reactions can be produced 

 by direct transference of force, as those produced by a blow or by rubbing. 



The essential point is only that the substance causing the reaction 

 has the power of producing a certain kind of motion in the atoms making 

 np the molecules of the substance which undergoes a catalytic reaction. 



Catalysis tnaij he thus defined as a condition of motion in the atoms of 

 unstable compou)ids which is produced hy motion proceeding from some 

 other substance^ and, which is accompanied hy a loss of energy, and leads to 

 the formation of new compounds. 



Catalytic action would not have been dwelt upon so long if it did not 

 play such an important part in the life of plants and animals. The 

 entire digestive process in the animal from the taking in of food through 

 the mouth to its excretion in the feces is one unbroken chain of catalytic 

 reactions. We have just the same thing with plants. When the seed 

 is sprouting, starch, fat, and albuminoids are changed into other com- 

 l)ounds by catalytic processes. The transference of many substances 

 from one part of a plant to another depends npon the same thing as 

 does also the power of absorbing substances rendered soluble in the 

 animal body. 



This principle once recognized, it is perhaps going only a step further 

 to ascribe the formation of all organic substances to catalytic reactions. 



Ordinary starch and fat are generally considered to be the first sub- 

 stances produced by plants since they are found in the protoplasm of 

 the plant containing the chlorophyll. Are these formed directly from 

 carbon dioxid and water with liberation of oxygen ? It seems much 

 more probable that, according to von Baeyer's extremely ingenious 



