30 



PROTOPLASM AND THE CELL 



tion of magenta. The nucleus is larger and more conspicuous 

 in large cells and may be found in the process of division (Fig. 

 13). Fat droplets and vacuoles also, vary in number and size 

 according to the conditions. 



FIG. 13. Yeast cells with successive stages in the process of budding. (From 

 Sedgwick and Wilson.) 



REPRODUCTION 



Budding. In active, growing yeast it is very easy to find 

 cells in the process of reproduction. This is brought about by 

 budding or gemmation, which begins with a local swelling usu- 

 ally at one pole of the spheroidal cell. The membrane appears 

 to give way or to weaken at one point and the inner protoplasm 

 presses into the region forcing out the thinned membrane, until 

 a well-marked bud is formed. Later this bud is constricted off 

 and it becomes a separate, young, yeast cell. Frequently the 

 bud continues to grow until mature without breaking away from 

 the parent cell, and may even bud in turn, thus giving rise to 

 chains of yeast cells (Fig. 14). 



