278 Transactions of the Canadian Institute. [vol. ix 



much of the work at present being done with the object of learning 

 more about the nature of the action of enzymes. The chemists have 

 reached a point at which they need the assistance of physicists, and phy- 

 sical chemistry is busy endeavouring to understand the nature and prop- 

 erties of colloidal solutions and the forces exhibited at the surface of 

 substances suspended in fluids because it is felt that in this way light 

 may be thrown upon the catalytic phenomena of the chemistry of life. 

 . i^ijBut there are other catalytic phenomena, other instances of pro- 

 found modification of the course or velocity of chemical change, which 

 are familiar in the study of the chemistry of inanimate nature, which it 

 would be premature at the present time to coerce into conformity with 

 this conception of catalysis, with the conception, that is, that catalysis 

 is due to surface condensation. Chemists speak of induced reactions 

 when a reaction which does not otherwise make itself manifest is caused 

 to become manifest by the simultaneous occurrence of another reaction. 

 Sodium arsenite dissolved in water and shaken with air undergoes no 

 detectable change. A solution of sodium sulphite, on the other hand, is 

 readily oxidized in this way. If a solution of both salts together is 

 treated thus, both salts are oxidized. There are indications that some of 

 the changes that occur in the body of men and animals, that make the 

 course of metabolism so hard to unravel, are instances of such induced 

 reactions. A very well-known and very remarkable fact in animal met- 

 abolism appears to require some such explanation. A man's food ordin- 

 arily consists of three principal classes of chemical compounds, proteins, 

 fats and carbohydrates. Of these, proteins are indispensable because 

 they alone supply nitrogen and sulphur v/hich are coiistantly being given 

 off and must be replaced. But though the carbohydrates contain no 

 elements that are not supplied by either fats or proteins they are also 

 indispensable. It is not very difficult to devise a diet for a man that 

 would contain no carbohydrate, but so far as its elementary composition 

 and the energy it is capable of developing in the body is concerned be 

 theoretically sufficient. But no such diet can be taken for more than 

 tVvO or three days without serious illness and signs that the chemical 

 utilization of the food given is not being perfectly carried out. Organic 

 substances leave the body unburnt that are never allowed to leave it in 

 health when the diet contains even a small amount of carbohydrate. 

 And as soon as a little starch or sugar is added to the experimental diet 

 the symptoms disappear and the complete oxidation of fats and proteins 

 is normally and easily effected again. One of the principal dangers in 

 the disease diabetes, in which the body has lost the power of properly 

 oxidizing sugar, consists in the tendency for the same abnormality in 

 the course of the oxidation of fats and proteins to occur, which is so easily 



