356 Messrs. E. J. Caldwell and S. L. Courtauld. [May 9. 



Table V. — Action of Extracts of Bottom Yeast prepared at 25°. 



Grlucoside used. 



Time of 

 extraction. 



Treatment of extract. 



Amount hydrolysed at 25°. 



24 hours. 48 hours. 72 hours. 



Amygdalin 



Maltose 



Methyl-a-glucoside 



hours. 



20 

 4 

 4 



4 



20 

 4 

 4 

 4 



20 

 4 

 4 

 4 



Unheated 



Heated at 35° (3 hours) 

 50° 



Unheated 



Heated at 35° (3 hours) 



„ 50° „ 



Unheated 



Heated at 35° (3 hours) 

 50° 



per cent. 

 7 

 4 

 3 

 2 



71 



59 



59 







76 



55 



50 



2 



•9 



15' 



•6 



8- 



•8 



7- 



•9 



5«< 



•o 



82- 



•1 



70-' 



•1 



73-^ 



•o 



l-< 



•6 



88 -J 



•8 



71- 



•2 



67 -J 



•1 



1-' 



per cent. 



per cent. 



10*4 

 8-8 

 5-0 



78-8 



81-5 



1-2 



80-3 



78-7 

 3-6 



Non-identity of Invertase and " Amygdalase." — The observations (recorded 

 in Table II) that amygdalin was not attacked by an extract which had been 

 prepared at 55° not only led us to think that the hydrolysis of amygdalin 

 by yeast was not conditioned by maltase, but also that invertase was not the 

 active cause of change — inasmuch as it is well known that invertase is far 

 from being destroyed at this temperature. Experiments which are recorded 

 in Tables VI and VII were made to test this point directly. The results 

 show that the assumption made by Marino and Sericano before referred to 

 cannot *be accepted. An extract which has been heated at 60° and is entirely 

 without action on amygdalin and methyl-a-glucoside still preserves much of 

 its activity towards cane-sugar. 



Marino and Sericano removed the maltase from the mixture of enzymes 

 derived from yeast by subjecting the extract to diffusion ; they overlooked 

 the possibility that the less diffusible fraction — which they proved to be 

 free from maltase — contained any other enzyme than invertase. 



It may be mentioned as a point of interest that bottom yeast, although 

 equally rich in maltase, appears to contain a far smaller proportion of both 

 invertase and amygdalase than top yeast. At the end of 24 hours only 

 2*7 per cent, of amygdalin and 91*5 of cane-sugar had been hydrolysed by an 

 extract of bottom yeast as compared with 10*5 per cent, of amygdalin hydro- 

 lysed by an extract prepared under like conditions from top yeast, which also 

 hydrolysed cane-sugar completely in the course of a much shorter period than 

 24 hours. The extreme activity of top yeast towards cane-sugar is clearly 

 indicated by the results given in Table VII. 



