586 Prof. H. E. Armstrong and Mr. H. W. Gosney. [June 13, 



It remains to consider the distinct effect produced by galactose. 



On reference to the diagrams figs. 6 and 7 representing the spatial arrange- 

 ment of the atoms in the two sugars, it will be noticed that the only 

 difference between them is that the hydrogen atom X shown to the left of the 

 oxygen atom in the ring is in a plane behind the ring in the one case, and in 

 a plane in front of the ring in the other ; there is also a corresponding- 

 difference in the relationship of the linking oxygen atom to the ring plane. 

 The difference between the close packed assemblages, therefore, would 

 probably be small : though sufficient perhaps to reduce the compatibility of 

 the two molecules, some degree of compatibility might still persist. 



This is one of those cases of minute difference which it will be important 

 to study further, especially in view of the observation made by more than 

 one worker that some yeasts " acquire " the power of fermenting galactose if 

 habituated to its presence. The question of the presence of a distinct 

 enzyme in emulsin capable of hydrotysing milk sugar and presumably of 

 inducing the synthesis of /3-galactosides must also be reconsidered from this 

 point of view : we are at present engaged in this inquiry. 



Studies on Enzyme Action. XXI. — Lipase (III). 

 By H. E. Armstrong, F.E.S., and H. W. Gosney. B.Sc 



(Eeceived June 13, — Read June 26, 1913.) 



On account of the part which Lipase plays in promoting the resolution of 

 fats generally into fatty acid and glycerol, one of the most important 

 processes in animal nutrition, it is desirable that a clear picture should 

 be obtained of the manner in which the activity of the enzyme is exercised. 



The material hydrolysed — the fat — being practically insoluble and the 

 enzyme presumably a colloid, the interaction to be considered is that of 

 substances insoluble in water and therefore presents unusual features. 



Two brief communications on the subject were made to the Society in 

 1905 and 1906.* In the first of these, which had reference to the enzyme 

 in castor oil seeds, it was stated that Connstein's contention had been 

 confirmed that the presence of acid is necessary to condition the hydrolysis 

 of a fatty oil by the enzyme and that practically any acid was effective 

 provided a sufficient amount were used. As acids did not act equally in 

 * ' Koy. Soc. Proc.,' B, vol. 76, p. 606 ; vol. 78, p. 376. 



