ALCOHOLIC FERMENTS. 133 



found that when these two values are graphically represented 

 with the degrees of temperature as abscissae and the time 

 intervals as ordinates, the curves obtained for all six species 

 had essentially the same form. They sink from the ordinates 

 of the lowest temperatures towards the axes of the abscissae, 

 and then rise from these ; at the same time, however, it is 

 seen from these curves that the cardinal points determined 

 / more especially from the highest and lowest temperatures, 

 give characteristic distinctions for the different species ; that 

 is to say, that the limits of temperature within which the 

 formation of spores can take place are different for the 

 various species (compare classification of the genus Sac- 

 charomyces). 



With regard to the time required for the appearance of 

 the first indications of spore-formation in the six species 

 investigated under the same conditions of temperature, the 

 following was observed : At the highest temperature the time 

 required for the development was in all the species about 30 

 hours ; at 25 there was also no great difference in the time 

 required ; at the lower temperatures., however, very evident 

 differences occurred. Thus, in the case of Sacch. cerevisice /., 

 the first indications of spore-formation at 11*5 C. are only 

 found after ten days ; in the case of Sacch. Pastorianus II. 

 after 77 hours, and so on. 



In all determinations of this kind a very considerable 

 influence is exerted by the condition of the cells, according 

 to whether they have been grown at a high or low tempera- 

 ture, whether they were old or young, feeble or vigorous, 

 etc., etc. It follows from this that the composition of the 

 nutrient fluid also exercises an influence. In methodical, 

 comparative experiments of this nature, a necessary condition 

 is, therefore, that the previous cultivation of the cells should 

 always be carried out in the same manner. If these external 

 conditions be varied, the limits for the reactions of the species 

 corresponding to such varied conditions must likewise be 

 determined. 



