304 



MICRO-ORGANISMS AND FERMENTATION. 



characterised either by their mode of germination or by the 

 form of their spores (S. anomalies, etc.). 



After a lapse of time, dependent on the species, roundish 

 particles of protoplasm appear in the cells ; these are the first 

 indications of spores (Fig. 52). In their further development 

 they are surrounded by a wall, which is more or less clearly 

 defined in the different species. 



In most species the spores are spherical. S. anomalus 

 forms an exception with its hemispherical spores, S. Marxianus 

 and S. fragilis with kidney-shaped spores. 



Two distinct types of germination may be distinguished. 

 In the first type, to which S. cerevisice I. belongs, the spores 

 may expand during the first stages of germination to such an 

 extent that the pressure which they exert on each other, while 



Fig. 52. The first stages of development 

 of the spores of Saccharomyces cerevisice 1. 

 (after Hansen). a, b, c, d, e, rudiments of 

 spores, where the walls are not yet distinct ; 

 /, /, h, i, j, completely-developed spores with 

 distinct walls. 



Fig. 53. Spores of Saccharomyceg cere- 

 visice 1. in the first stages of germination 

 (after Hansen). At a, d, e, and g, formation 

 of partition walls; e, f, and g, the walls of 

 the mother-cells have become ruptured ; 

 g, a compound spore divided into several 

 chambers, the coherent wall is ruptured in 

 three places. 



they are still enclosed in the mother-cell, brings about the 

 formation of partition walls (Fig. 53). This is caused by the 

 wedging or squeezing together of the protoplasm between the 

 spores, or else the walls of the spores may be brought into 

 close contact. During further development, a complete union 

 of the walls may take place, so that a true partition wall 

 results ; the cell then becomes a compound spore divided into 

 several chambers. 



During germination (Fig. 54) the spores swell and the wall 

 of the mother-cell, which was originally fairly thick and 

 elastic, stretches out and consequently grows thinner. It is 

 finally ruptured, and then remains as a loose or shrivelled 



