136 



SCIENCE. 



[N. S. Vol. XXII. No. 553. 



scure. A large and interesting literature 

 has grown up around the discussion. A 

 word must be said, however, about the im- 

 portant discussion started two years ago 

 by Cohnheim when he announced the rela- 

 tion of two distinct ferments to the oxida- 

 tion of carbohydrates in the body. The 

 bearing of this on the question of diabetes 

 was immediately recognized and numerous 

 investigations were launched to throw more 

 light on the subject. According to Cohn- 

 heim the pancreas furnishes one of these 

 enzymes and the muscle substance the 

 other. One may serve as a kinase or acti- 

 vator for the other and the effect of the 

 two is to facilitate oxidation in the muscles. 

 The subject is immensely important, but the 

 latest studies do not seem to fully confirm 

 all tjie Cohnheim statements. 



In connection with the subject of enzymes 

 reference must be made to the considerable 

 number of papers which have appeared in 

 the last few years on the question of the 

 relation of the ferments to the simple in- 

 organic katalytic agents. Beginning with 

 the work of Tammann published in the 

 Zeitschrift fiir physikalische Chemie many 

 attempts have been made to express the 

 velocity of enzyme reactions by equations 

 analogous to those suggested by Wilhelmy 

 for the inversion of sugar. The extended 

 investigations of Tammann led in general 

 to formulas which were more complicated 

 than those corresponding to the simple 

 logarithmic curve. Some of the more re- 

 cent work, especially that of Henri, has led 

 to more definite results. This whole dis- 

 cussion has been well reviewed by Bredig 

 in volume 1 of the Ergebnisse der Physiol- 

 ogie. 



One of the most interesting developments 

 in recent physiological chemistry is in the 

 discussion of theories of immunity and the 

 relations of toxins and antitoxins. As first 

 presented by Buchner, Bordet, Ehrlich, 



Pfeiffer and others, these doctrines ap- 

 peared from the chemical standpoint wholly 

 visionary and intangible, but in the last 

 few years a great change has followed in 

 the attitude of chemists and now some of 

 the phrases of the immunity theory of 

 Ehrlich have become part of the language 

 of organic chemistry. 



It was early recognized that toxins and 

 antitoxins act on each other in a manner 

 suggesting combinations in definite chem- 

 ical proportions, and attempts were soon 

 made to work out the laws of the union. 

 The earlier Ehrlich experiments seemed to 

 point to simple combinations like those be- 

 tween an acid and a base, the union fol- 

 lowing to complete saturation. It was 

 recognized later, however, in many cases, 

 that the reaction is not complete and that 

 the saturation curve is far from being a 

 straight line. These observations led to 

 various speculations. Ehrlich assumed 

 that in the ordinary toxin mixtures we 

 have certain modified forms known now as 

 toxoids and toxons, which, while non-toxic, 

 have saturating power resembling that of 

 the toxins. Hence the amount of anti- 

 toxin added to a toxin solution to destroy 

 its toxicity would have to be sufiicient to 

 combine, not only with the real toxin, but 

 with any toxoid or toxon present also ; just 

 as in neutralizing free sulphuric acid by 

 sodium carbonate the amount of the latter 

 necessary would 'have to be increased if 

 some salt decomposable by sodium carbon- 

 ate, such as alum, is likewise present. In 

 the one case as in the other the simplicity 

 of the reaction would be obscured by com- 

 plexity of the mixture. 



Arrhenius and Madsen, and others fol- 

 lowing them, have been led also to study 

 these extremely important phenomena and 

 have given a different interpretation. Ac- 

 cording to the notions of the physical chem- 

 ists these reactions are more or less per- 



