INFLUENCE OF HEAT, ETC., IN VITALITY. 421 



the heating in water test was found to be 50 C., whereas after 

 heating for half an hour at 55 C., Mycoderma films were 

 developed in all the check inoculations heated in wort. Older 

 cultures proved better able to stand the heat than younger ones, 

 the difference being 5 C. The formation of resting cells is not 

 considered to account for this, Will's explanation being that the 

 older and more strongly developed cells possess greater powers of 

 resistance than such as are younger and more delicate. Seif ert 

 gives o-4o C. as the limits of temperature between which 

 Mycoderma cells are capable of development, the presence of 

 alcohol narrowing the range for instance, down to between 2 

 and 33 C. in wine containing 8 per cent, of alcohol by volume. 

 A continuous exposure of five minutes to a temperature of 60 C. 

 is sufficient to destroy the vitality of Mycoderma in wine. 



With regard to the influence of chemical agencies on the life 

 of Mycoderma cells, the investigations of Holm and Jbrgensen 

 show that the development of the cells is accelerated by the 

 addition of small quantities of fluorides. Siebel found that 

 neither yeast, Mycoderma nor bacteria will develop in beer that 

 has been treated with a solution of formalin (40 per cent, solution 

 of formaldehyde) in the proportion of i: 10,000; whilst in 

 solution of i : 50,000, yeast and Mycoderma were able to grow, 

 but not bacteria. According to SEIFERT (II.), the various 

 Mycoderma differ considerably in their power of resisting the 

 influence of alcohol, development ceasing in presence of 13 per 

 cent, of that substance by volume. In the case of furfurol, 0.5 

 per cent, was fatal to Will's Mycoderma. Sulphur dioxide is also 

 known to be very poisonous to Mycoderma, and is therefore used 

 in curing beverages that have been attacked by these organisms. 

 WESENBERG (I.) investigated the action of antigermin, mikrosol, 

 afral, mycelicide and antiformin on Mycoderma cerevisice, to 

 ascertain the amount of a fatal dose. On immersion in a 2 per 

 cent, solution of the antiseptic, the cultures, 4 days old, were 

 killed by antiformin in J hour, by antigermin in i hour, by 

 mikrosol in 8 hours, and by mycelicide in 9 days, whilst afral 

 merely retarded their growth. In a i per cent, solution of the 

 poison the Mycoderma perished in J hour with antiformin, 5 hours 

 with antigermin, and 8 hours with mikrosol. The results were 

 very different, however, when the antiseptics were added in 

 definite quantity to beer wort, the growth of Mycoderma being 

 then arrested by the following degrees of concentration : anti- 

 germin, i : 1000; mikrosol, i : 5000 ; antiformin, i : 20. The 

 most powerful antiseptic, as regards the restriction of develop- 

 ment, was undoubtedly antigermin, which, according to 

 Wesenberg, is from 3 to 10 times as strong as mikrosol. 



