1894.] MICROSCOPICAL JOURNAL. 4.3 



which deserve careful revision in this regard, are studied 

 in pure cultures, it will soon be seen that their nature is 

 different from that of the Haccharomycetes. 



It will be seen that Hansen's name is intimately con- 

 nected with all these questions. During the last fifteen 

 years this eminent investigator has inaugurated a reform 

 in the industrial branches that are based upon fermenta- 

 tion. This principle is to work in praxis with pure cul- 

 tures exclusively, and through the efforts of Joergensen 

 and other investigators, his methods are now partly or 

 wholly adopted all over the world. His views are at 

 present entering the milk industry, and the manufactur- 

 ing of wines. Much has yet to be done, but it is seen 

 that the old principle of keeping gardens and fields free 

 from weeds must be recognized also by lower plants, and 

 especially when the successful maintenance of this prin- 

 ciple stands behind great factors in the life of individ- 

 uals and nations. 



LITERATURE. 



(a). On pure cultures : 



Hansen: Meddelelser fra Carlsberg Laboratoriet, Vol. 

 II, Part 2; Vol. II, Part 4; Vol. Ill, Part IL (1883-1892). 

 Transactions of the Laboratory Club, London, 1889. 

 Holm : Medd. Carlsb. Labor. Vol. Ill, Part 1, 1891. 



(b). On fractional cultures : 



Lister: Quart. Journ. Micr. Science. XVIII, 1878. 

 Klebs : Archiv f. experim. Pathologie, I and Hansens pap- 

 ers. 



Cc). 0)1 water and air-analysis : 



Hansen : Methode fur Analyse desBrauwassers in Ruck- 

 sicht auf Mikroorganismen. (Zeitschrift fur das ges- 

 ammte Brauwesen 1888, No. 1). Ueber die zymotechnis- 

 che Analyse der Mikroorganismen der Luft. (Prager 

 Brauer und Hopfenzeitung, Prag 1888, No. 19). 



(d). Historical : 



A. Joergensen : Ueber den Unterschied zwischen Pas- 

 teur's und Hansens Standpunkt in der Hefefrage. (Zeit- 

 schrift fur das gesammte Brauwesen, 1888). Also : Pas- 

 teur : Etudes sur la biere, Paris 1876 (engl. transl. exist- 



