142 MICRO-ORGANISMS AND FERMENTATION. 



was required for the formation of films which were generally 

 more feebly developed. This species and Sacch. Pastori- 

 anus III. also develop a vigorous film comparatively 

 rapidly at the ordinary room-temperature, whilst in the 

 same time the other species are left far behind. 



As mentioned above, the film-formations have different 

 maximum temperatures. This is related to the fact that 

 the maximum temperature for budding is not the same 

 for the different species. It was proved that budding and 

 fermentation can take place at temperatures at which film- 

 formation no longer occurs. Thus, in the case of Sacch. 

 cerevisice /., Sacch. ellipsoideus I. and Sacch. ellipsoi- 

 deus II. Hansen still observed a vigorous fermentation and 

 budding at 38 to 40 C., and at 34 C. also in the case 

 of the three species of the group Sacch. Pastorianus. A 

 relationship is thus shown to exist between the influence 

 of temperature on budding and fermentation on the one 

 hand, and film-formation on the other. 



(d) The Temperature Limits for the Saccharomycetes. 

 Just as the influence of temperature on the development of 

 spores and films varies with the different species, so it has also 

 been shown by Hansen's investigations (1883) that both 

 spores and vegetative cells of different species likewise possess 

 unequal powers of resistance to hot water. In this respect the 

 spores have a greater resisting power than the vegetative cells. 



In experiments of this nature, as in the cases previously 

 mentioned, the condition of the cells has a very marked effect 

 on the results, which are especially influenced according as 

 old or young cells have been employed. Thus, it was found 

 that the cells of Sacch. ellipsoideus //., which had been 

 cultivated in wort for two days at a temperature of 27 C., 

 were killed in five minutes when heated to 56 C. in sterilised 

 distilled water, whilst cells of a similar culture but 2 J months 

 old were able, under similar conditions, to withstand five 

 minutes' heating to 60 C. without being killed. 



Eipe spores of the same species, which had been developed 



