72 MORPHOLOGY AND CULTURE .OF MICROORGANISMS 



slender part ends by breaking (Fig. 54, 2, 3 and 4). The cell, there- 

 fore contains at this time at each of its poles a small mass of sporo- 

 plasm having first one, then two, nuclei (Fig. 54, 5 and 10). After 

 this, the sporoplasm condenses around each of these nuclei (Fig. 

 54, 6), thus delimiting at each of the poles two small ascospores. 



During these phenomena, the metachromatic corpuscles congre- 

 gate around the ascospores (Fig. 54, n and 12), then gradually dis- 

 solve. The ascospores constantly increase in size at the expense of 

 the epiplasm, which becomes disorganized and is reduced to a vacuo- 

 lar liquid containing in suspension metachromatic corpuscles, fat 

 globules and glycogen. They succeed in absorbing entirely the epi- 

 plasm and in occupying the whole of the ascus (Fig. 54, 13 and 14). 

 The metachromatic corpuscles, like the glycogen and the globules of 

 fat, are then completely absorbed by the ascospores, which indicates 

 clearly that they, as well as the latter substances, act as reserve prod- 

 ucts. When the ascospores are ripe, they contain in their vacuoles 

 metachromatic coipuscles (Fig. 54, 14). 



FIG. 55. Germination of ascospores in Saccharomyces ludwigli. i, Beginning 

 of the fusion of the ascospores. 2, The ascospores are joined two by two by a 

 channel of copulation, but their nuclei are not yet fused. 3, The nuclei are fused. 



4, At the left two ascospores, joined, have formed at the middle of the channel of 

 copulation a bud which has ruptured the membrane of the ascus. At the right, the 

 two ascospores, joined by a channel of copulation have not yet fused their nuclei. 



5, Formation of the bud at the expense of the two fused ascospores. Two other 

 ascospores have not yet begun their fusion. 6, The bud formed at the channel of 

 copulation is already established and separated from this channel by a transverse 

 septum. 



In all yeasts, at the time of budding, the ascospores have the appear- 

 ance and structure of plant cells. Their germination does not differ 

 from ordinary plant multiplication. In some species, however, espe- 

 cially in S. ludwigii, copulation, suppressed at the beginning of sporula- 



