52 CYTOLOGY OF YEASTS 



an alveolar structure. Each of these surrounds itself with a small 

 zone of dense protoplasm, and then transforms itself into ascospores. 



.. These grow at the expense of the cyto- 

 Qr| plasm until they occupy the whole asc. 1 

 The cytological phenomenon of the 

 Fig ' 5 s P e?rJ n Ll ^ formation of ascospores presents many 



characteristics in common with that 



observed in the ascs of other Ascomycetes, especially the endomycetes. 

 The germination of ascospores when they are not accompanied 

 by a copulation, does not offer any special characteristic. The asco- 

 spores in time swell up and are transformed into vegetative cells which 

 bud after the normal procedure. (Fig. 52.) 



1 Beauverie has proposed a method for staining ascospores. The yeast should 

 be fixed in alcohol or formol and stained with carbol fuchsin heating to the point 

 where vapor is given off. It should then be decolorized by 1-3 acetic acid, 

 washed in water and stained by thionine. The spores will be stained red and 

 the rest of the cell blue. This ability to resist acids is especially marked in 

 Schizosaccharomyces octosporus. Beauverie, J., Quelques proprietes des asco- 

 spores de levures. Technique pour leur differentiation. Comp. Rend. Soc. Biol. 

 80 (1917), 5. 



