REPRODUCTION BY BUDS 21 



are still very small and simple. The cells are more plump 

 than the bacteria usually are, varying from elongate to 

 nearly globular. When condi- 

 tions are good for their life, and 

 one of these cells becomes 

 nearly the mature size, the 

 growing matter within pushes 

 out a little pouch in the wall 

 and some of it flows into this 

 rounded pocket. This is called 

 a bud, and it continues to grow, 

 remaining attached to the old 

 cell. Intimate internal commun- 

 ication is kept up between the Figure 4. Cells of yeast in 

 cells, somewhat like that be- various stages of budding 

 tween a small room and a larger room in the same house. 

 The bud is plainly the beginning of a young cell like the 

 first. As the bud grows larger the connection between it 

 and the mother cell becomes less. In the meantime the 

 first cell may start another bud from another point, or the 

 new cell may itself start a bud. In this way we may get 

 a considerable group of connected cells, some older and 

 some younger. Sooner or later, however, the daughter 

 cells, as they become older, fall apart from the mother 

 cell and thus become independent. How long they 

 remain together and how complex the chains become is 

 determined by the species of yeast and by the food, and 

 the conditions of moisture and temperature in which 

 they are growing. 



At other times the yeast cell may divide up the 

 protoplasm on the inside into four small cells, surrounded 

 by the old mother wall. After rest, these finally break 

 loose from the mother cell and live an independent life. 

 Then they grow up to the mature size and begin to 

 reproduce by budding again. This last is not budding. 

 It is more like fission. We shall refer to it again later. 



3. The Essential Nature of Budding. It will be seen 



