570 Drs. T. A. Henry and S. J. M. Auld. [July 22, 
ment carried out on similar lines with another portion of the same speci- 
men of yeast showed that after 11 days 67 per cent. of the amyedalin had 
been decomposed, after which the action appeared to cease. The residue left 
in. the flask after distilling off the benzaldehyde and hydrocyanic acid was 
evaporated to dryness on the water-bath and extracted with alcohol. ‘This 
solution was decolorised with animal charcoal and the solvent distilled off, 
leaving a quantity of. unchanged amyegdalin. This was extracted with ether. 
On evaporation of the solvent a minute quantity of a crystalline substance 
which was not amygdalin was obtained. The quantity of this material 
isolated was so small that it was impossible to further examine it, and its 
formation was not observed in any further experiment. It is possible that 
this substance was benzoic acid, since Herzog has shown* that salicyl alcohol 
is oxidised to salicylic acid by yeast, and it is conceivable that some of the 
benzaldehyde formed in this case may have similarly been oxidised to benzoic 
acid. No benzoic acid was obtained, however, by the action of yeast on 
small quantities of benzaldehyde suspended in water. 
The residue contained no dextrose, this having been changed by the zymase 
of the yeast forming alcohol and carbon dioxide, 
This decomposition of amygdalin by yeast does not seem to have been 
observed previously, though Bourquelot has ascribed such an action to 
Aspergillus ngert and Gerard to Penicillium glaucum.t 
These experiments having established the fact that the hydrolysis of the 
amyegdalin was brought about by the yeast, 1t was next sought to determine 
to which constituent of the yeast this hydrolytic action was due. 
Fischer§ has shown that a preparation of invertase obtained by washing 
yeast with water has the power of partially hydrolysing amygdalin, forming 
one molecule of dextrose and one molecule of mandelonitrile glucoside 
according to the equation 
CopH270uN + H2O = CuHiyOeN + CeH120¢. 
Amyedalin. Mandelonitrile Dextrose. 
glucoside. 
This experiment was repeated and no difficulty was experienced in obtaining 
mandelonitrile glucoside by this means, and under no circumstances was any 
formation of hydrocyanic acid or benzaldehyde observed when such yeast 
washings were added to a solution of amygdalin. The complete hydrolysis 
of this glucoside by yeast cannot therefore be due to the action of invertase. 
* ‘Zeit. Physiol. Chem.,’ 1903, vol. 37, p. 396. 
+ ‘Compt. Rend. Soc. Biol.,’ 1893, pp. 653 and 804. 
t Ibid., 1893, p. 651. 
§ ‘Berichte,’ 1894, vol. 27, p. 2989; 1895, vol. 28, p. 1809. 
