┌───────────────────────┬─────────────────────────────────────────┐ │ │ Relative Rates. │ │ Yeast. ├─────────────┬─────────────┬─────────────┤ │ │2·5 per cent.│2·5 per cent.│2·5 per cent.│ │ │ │ │ Glucose + │ │ │ Glucose. │ Mannose. │2·5 per cent.│ │ │ │ │ Mannose. │ └───────────────────────┴─────────────┴─────────────┴─────────────┘ S. Thermantitonum 100 105 92 Brewery yeast, 53 per cent. activity destroyed by heat 100 21 33 Brewery yeast, 60 per cent. activity destroyed by heat 100 12 42 ────────────────────────────────────────────────────────────────── The case of galactose merits special attention. Previous investigations [see Lippmann, 1904, p. 734] have shown that the fermentation of galactose by yeast differs greatly from that of the other hexoses. The subject has been re-investigated by E. F. Armstrong [1905], and by Slator [1908, 1]. Armstrong carried out his experiments in the manner already described (p. 131), and found that some yeasts had, and others had not, the power of fermenting galactose, although all were capable of fermenting glucose, fructose, and mannose. Slator made quantitative experiments on the same subject. He was able to confirm the statement which had previously been made, that certain yeasts which have the property of fermenting galactose possess it only after the yeast has become acclimatised by culture in presence of the sugar. This was shown for brewery yeast and for the species mentioned below. This phenomenon is one of great interest and is strictly analogous to the adaptation of bacteria which has now been quite conclusively established [Neisser, 1906].