528 ENZYMES DECOMPOSING SACCHARIDES. 



With regard to the influence of other enzymes: melibiase is 

 almost as indifferent as invertase. In the method of experiment 

 selected by BAU (XXVI.) see pp. 521 and 525, vol. ii. the only 

 difference between this and the extremely resistant invertase was 

 that, after the yeast had been treated with pepsin, melibiase could 

 be detected in the filtered-off yeast cells, but not in the filtered 

 solution. Melibiase seems therefore to be rather more sensitive 

 than invertase, though it is far more resistant than maltase. It is 

 also possible that melibiase is insoluble in faintly acid solid solutions, 

 since the nitrate from the pepsin treatment contains free hydro- 

 chloric acid; whilst HILL (I.) for instance, found that faintly 

 alkaline water is requisite for the extraction of maltase. Con- 

 sequently, it must be left for further investigation to determine 

 whether the sparing solubility of melibiase in water can be 

 increased by the careful addition of alkali carbonates. 



Melibiase occurs in all low-fermentation types of yeast, both 

 Frohberg and Saaz, an exception being afforded, according to 

 Lindner, by the low-fermentation beer yeasts, No. 2, No. 18, and 

 No. 389 of the Berlin collection, these yeasts leaving melibiose 

 "practically unfermented." According to BAU (XXVI.), how- 

 ever, the low-fermentation yeast No. 2 Victoria ferments 

 melibiose, though slowly and sluggishly. Like certain other 

 races, No. 18 is no longer grown in the Berlin collection, and 

 should therefore be struck out of the scientific literature, the 

 rediscovery, and especially the identification, of such yeasts being 

 a matter of very low probability. Yeast No. 389, Grafenthal, 

 does not ferment melibiose, and in this respect forms a remark- 

 able exception among the low-fermentation yeasts, all the others 

 (according to the researches of Bau) containing melibiase. 



As a rule the top-f errnentation yeasts do riot ferment melibiose, 

 Lindner's report that pressed yeasts No. 430, No. 487, and No. 

 574 decompose this sugar , being based on error. On the other 

 hand, melibiose is fermented by the top-fermentation beer yeast, 

 Liegnitz a No. 405, and by the pressed yeast, Winterhude, Race 

 III. No. 139. The yeasts, No. 600 and No. 603, from Danish 

 " Jopen " beer ferment melibiose ; but contrary to Lindner's 

 report, Broyhan yeast No. 330 (?) does not. These two classes of 

 beer contain numerous organisms that cannot be classed along 

 with culture yeasts ; and it is therefore not surprising to find 

 that they contain fungi capable of attacking melibiose. The only 

 true top-fermentation yeasts that split up this sugar are the beer 

 yeast Liegnitz a No. 405, and the pressed yeast Winterhude, 

 Race III. No. 139. 



In spite of the low fermentation temperature, low-fermentation 

 yeasts occasionally assume a high-fermentation character, a 

 peculiarity first observed by E. C. HANSEN (LXV.) see pp. 264 et 

 seq., vol. ii. The same thing was also noticed by BAIT (VI.), at 

 intervals, in Holland; and similar communications have been 



