1894.] MICROSCOPICAL JOURNAL. 41 



at the bottom of the flasks. Such flasks as contain two 

 flocks are discarded, and only those containing one round 

 colony are kept, and further developed. Their contents 

 may be aerated by a slight stirring. The remaining part 

 of the procedure is the same as has been mentioned un- 

 der the heading of the absolute pure culture. This 

 method may give useful results, but as it is based upon 

 calculations which are to a certain extent uncertain, the 

 absolute pure culture is preferable. 



ZYMOTECHNIC WATER ANALYSIS. 



There is an essential difference between the hygienic, 

 (chemical and botanical) analysis of water, and the zymo- 

 technic analysis. While the former helps us to find the 

 pathogenic micro-organisms, and their products, as well 

 as such substances as are dangerous to the animal organ- 

 ism, the latter cares only for the organisms that are able 

 to develope in the beer or beer- wort. Many organisms 

 live and develope in water without having the slightest 

 effect upon beer-wort or beer. On the other hand, all or- 

 ganisms that will develope in beer, will also develope in 

 beer-wort. The procedure is : A few cm^^ s. of the con- 

 taminated water are disseminated into flasks with wort, 

 and the development is noticed for a term of fourteen 

 days. The preliminary examinations are like those em- 

 ployed by fractional cultures, one germ or cell being in- 

 troduced in each flask with the water. 



ZYMOTECHNIO AIR ANALYSIS. 

 It is important to know the nature and average number 

 of organisms in the air in and about breweries. The ex- 

 amination of the air is based upon the same principles as 

 that of water, but the organisms are here collected by 

 means of an aspirator. Such an aspirator has been con- 

 structed by Hesse (for figure and description, see Salomon- 

 sen, 1. c. page 505), and serves well for all purposes in 

 this connection. Aeroscopes or aerobioscopes have been 



