1904] Enzyme Action, Ionic-Dissociation, and Vital Change. 537 



behaviour to these circumstances alone. If osmotic pressure be 

 regarded as the outcome of some reciprocal interaction between solvent 

 and dissolved substance rather than as a mechanical effect, the fact 

 that the variation in osmotic pressure and in the value of K with 

 concentration follow the same law may be taken as evidence that the 

 increase in K with concentration when a sugar is hydrolysed with 

 the aid of an acid is the consequence of a diminution in the influence 

 exercised by the water. 



"Enzyme Action as bearing on the Validity of the Ionic- 

 Dissociation Hypothesis and on the Phenomena of Vital 

 Change." By Henry E. Armstrong, Ph.D., E.E.S. Eeceived 

 April 5 — Eead April 28, 1904. 



On several occasions of late years, I have protested against the 

 dogmatic attitude assumed by the advocates of the ionic-dissociation 

 hypothesis of chemical change and have remarked on the danger of 

 allowing a purely mathematical treatment to supersede a careful, 

 unbiassed consideration of the facts as these present themselves to the 

 chemist. I have insisted on the limited application of the hypothesis 

 — especially in explanation of the behaviour of the large majority of 

 organic compounds ; and have contended that an association hypo- 

 thesis is preferable and of far wider application : yet, in so doing, 

 I have always recognised that the dissociation hypothesis is often sus- 

 ceptible of numerical treatment in a way which places it at a great 

 advantage. 



Twenty years ago, I contended that the solvent played as important 

 a part as the dissolved substance in electrolytic changes ; then and for 

 some time afterwards the dissociationists regarded the solvent as a 

 mere screen. Gradually they have been led to recognise that the 

 solvent plays an active part and "ionising" solvents are now freely 

 spoken of : the admission has been made, however, tacitly and without 

 recognition of the fact that the difference of opinion is now reduced to 

 the one question — whether ions enjoy separate existence in solution : 

 whether, for example, in a solution of hydrogen chloride, free hydrogen 



* [Index supplied by author, classified according to the schedule of the Inter- 

 national Catalogue of Scientific Literature.] 



*[D 7050, 8020 ; Q 1230, M 3010.] 



*D 8030 Formation of carbohydrates in protoplasm. 



Grhicosamine, significance of, in enzymes. 



