262 INTERNATIONAL CONGRESS OP VITICULTURE 



yeast wines shows complete fermentation. Forty-five out of a total of 98 

 naturally fermented 1913 wines were above .4 per cent; 7 out of 68 of 

 wines made with SO 2 and pure yeast were above .4 per cent. Unfermented 

 sugar is not so good a criterion for judgment of the soundness of a wine 

 as is volatile acid, but is valuable when considered in connection with 

 volatile acid. That may be made plain by examples. A wine with .125 per 

 cent volatile acid and .5 per cent sugar is decidedly unsound; but one with 

 .05 per cent volatile acid and .5 per cent sugar can be gotten dry and can 

 be made into a perfectly sound wine. 



A comparison of the miscroscopical examinations of the various samples 

 is instructive. The "tourne" or "lactic bacterium" found in many California 

 wines is an anaerobic organism and the one which probably causes more 

 spoilage than all other organisms combined. It is no doubt identical with or 

 very similar to the bacterium of "tourne" of French wines or the Bacterium 

 Maanitopoeum described by Peltier.3 Wines with high volatile acid and un- 

 fermented sugar and badly infected with "tourne" bacteria will almost in- 

 evitably spoil completely unless something radical is done to stop the bac- 

 terial action. 



Fifty-four out of 66 naturally fermented wines examined were badly 

 attacked by tourne bacteria; several more contained smaller numbers, leav- 

 ing only a very few not visibly infected at the time of analysis. Only 7 out 

 of 68 of the wines made by the improved method showed any tourne bacteria 

 and these exhibited only small numbers. 



Comparison 1914 Wines. 



The 1914 fermenting season was very cool and hot fermentations were 

 less common than in 1913. Since hot fermentations cause most "stuck" 

 wines with their attendant high volatile acid and bacterial content, we should 

 therefore expect to find less marked difference in the qualities of the 1914 

 wines than in the case of the 1913 wines. This is found to be true as an 

 examination of Tables 3 and 4 will show. 



Thirteen out of a total of 61 naturally fermented 1914 wines were above 

 .10 per cent volatile acid and 10 were above the commercial limit of .10 per 

 cent. Of the wines made with SO 2 and pure yeast none were above .10 

 per cent and all were very much below .140 per cent. The average in the 

 two cases were .049 per cent and .098 per cent respectively. 



Of the naturally fermented wines, 8 out of 45 contained more than .4 

 per cent sugar. Of those fermented with pure yeast and SO 2 , 8 out of a 

 total of 60 contained more than .4 per cent sugar. 



Microscopical examination showed 15 out of a total of 50 naturally fer- 

 mented wines to be badly attacked by "tourne" bacteria. The wines 

 fermented with pure yeast and SO 2 did not exhibit large numbers of tourne 

 bacteria in any case and in only two instances were any found. 4 



On the whole, the difference in quality between the wines made by the 

 two methods in 1914 is not so great as in 1913, but is nevertheless distinct 



3See Revue de Viticulture, vol. 40, pp. 161-167. 



4 The microscopical examinations were all made on the non-centrifuged 

 sample; a wine showing large numbers of "tourne" bacteria by this method 

 was considered badly infected. 



