150 MICRO-ORGANISMS AND FERMENTATION. 



During germination the spore swells and the projecting 

 rim may either remain or disappear. Buds then make 

 their appearance at different points on the surface of the 

 spore. 



One of the objects of HANSEN'S investigations was also 

 to determine in what way the formation of spores was 



FIG. 42. Germination of spores of Saccharomyces anomalus (after HANSEN). 



influenced by different temperatures, with a view of ascertaining 

 whether the different species behave alike, or whether it might 

 not be possible in this way to discover different characteristics. 

 It was, therefore, necessary to determine : First, the limits of 

 temperature, i.e., the highest and lowest temperatures at which 

 spores could be formed ; secondly, the most favourable tem- 

 perature, i.e., the temperature at which spores appeared in the 

 shortest time ; and, thirdly, the relation between the inter- 

 mediate tem%)eratures. 



In determining the required intervals of time, the moment 

 was registered at which the cells showed distinct indications of 

 the formation of spores (compare Figs. 37 and 43). It is not 

 possible to make use of ripe spores in these determinations, 

 since no criterion exists for complete ripeness. 



The results obtained by HANSEN are as follows : 

 The formation of spores takes place sloivly at low temperatures, 

 more rapidly as the temperature is raised to a certain point ; 

 when this point is passed, their development is again retarded, 

 until finally a temperature is reached at which it ceases 

 altogether. 



