252 SUMMARY OF CURRENT RESFARCHES RELATING TO 



Organisms in the Mould of Beer* — E. C. Hansen's continued 

 experiments on this subject are characterized, as before, by the use of 

 a single nutrient fluid, viz. sterilized wort. As before, test-tubes were 

 empluyed, which during the ebullition of the wort were bound round 

 with gauze and filter-paper ; vacuum-retorts were also used and closed 

 while the nutrient fluid was btiiling, and allowed to stand until, 

 judging from previous experience, no new forms were likely to 

 develope. 



As before it was proved that the air in many neighbouring places 

 may contain, not only a varying number of organisms, but also distinct 

 kinds. The experiments with the vacuum-retorts show that the micro- 

 organisms of the air may ai)pear partly in groups and clouds, with 

 intermediate spaces entirely free from germs, and partially scattered 

 singly in the atmosj^here. The seasons of the year exercise a decided 

 influence ; but this, being complicated by other factors, is not always 

 evident. The source of micro-organisms is easily recognized through 

 working out a large number of analyses. Researches into the appear- 

 ance of the species of Saccliaromyces in the air of the garden show 

 this clearly. Thus these yeast-fungi were found in abundance in the 

 ail" under cherry trees from the beginning of July to the end of 

 August in 1879, and to the end of September in 1880, but on the other 

 hand none or very few appeared under vines. In accordance with 

 this, we find that the cherries were ripe at the period named, but the 

 grapes were not. In the season of 1879 fruit was more abundant in 

 the gardens experimented on than in that of 1880, and there was a 

 richer harvest of Saccliaromyces in the former year than in the latter. 

 The fruit season, August and September, was also the period in which 

 these fungi were most abundant in the air. Experiments have proved that 

 Saccharomyces Cerevisice, j^astorianus, and ellipsoideus, can live through 

 the winter in the earth, and there is much evidence that these sjiecies 

 pass through a similar cycle of changes in nature as S. apiculatus. 

 The two months named were also those in which bacteria appeared in 

 the largest numbers. Amongst the observed organisms the mould- 

 fungi were the most abundant, next came the bacteria, and lastly, the 

 Saccharomyces. In both places of observation (under cherry trees 

 and vines), the same organisms were generally found to be most 

 abundant. 



Amongst the most important results of experiments made in 

 various breweries are the following: The vapour of the malt did 

 not, as one might have supposed, carry away the bacteria and other 

 . organisms which are in the body of the malt. The air in the malt- 

 house at Alt-Carlsberg infected all the opened retorts; the mould-fungi 

 were especially abundant here. In the fermenting chamber of another 

 brewery foreign yeast-fungi, which produced disturbance in the 

 manufacture, were commonly met with. The air in the fermenting 

 chamber at Alt-Carlsberg was distinguished for its great purity, it 

 contained even fewer organisms than the air of the garden. This is 

 ascribed to the fact that the air in this cellar is cooled by refrigerators, 



* Eesume des Meddelelser fra Carlsberg Laboratoriet, i. (1882). See Bot. 

 Ccntralbl., xi. (1882) pp. 6-8. Cf. this Journal, ii. (1882) p. 234. 



