vii . GEMMATION 73 



The mode of multiplication of Saccharomyces is readily 

 made out in actively fermenting yeast, and is seen to differ 

 from anything we have met with hitherto. A small pimple- 

 like elevation (c, bd) appears on the surface of a cell and 

 gradually increases in size : examined under a high power 

 this bud is found to consist of an offshoot of the protoplasm 

 of the parent cell covered with a very thin layer of cellulose : 

 it is formed by the protoplasm growing out into an offshoot 

 like a small pseudopod which pushes the cell-wall before 

 it. While this is going on the nucleus passes to the surface 

 of the cell and divides, one of the products of fission remaining 

 in the mother-cell, the other in the bud. The bud increases 

 in size (bd') until it forms a little globular body touching 

 the parent cell at one pole : then a process of fission takes 

 place along the plain of junction, the protoplasm of the bud 

 or daughter cell becoming separated from that of the mother- 

 cell and a cellulose^ partition being secreted between the 

 two. Finally the bud becomes completely detached as a 

 separate yeast-cell. 



It frequently happens that a Saccharomyces buds in 

 several places and each of its daughter cells buds again, 

 before detachment of the buds takes place. In this way 

 chains or groups of cells are produced (B), such cell- 

 colonies consisting of. two or more generations of cells, the 

 central one standing in relation of parent, grandparent, or 

 great-grandparent to the others. 



It must be observed that this process of budding or 

 gemination is after all only a modification of simple 

 fission. In the latter the two daughter-cells are of equal size 

 and are both smaller than the parent-cell, while in gemma- 

 tion one the mother-cell is much larger than the other 

 the daughter-cell or bud and is of the same size as, indeed is 

 practically identical with, the original dividing-cell. Hence 



