10 MORPHOLOGY AND DEVELOPMENT OF YEASTS 



rates. The daughter cell increases in size and soon equals that of 

 the mother cell after which it, in turn, buds. 



As has been said above, when multiplication is very active, each 

 cell forms many buds simultaneously on different parts of its sur- 

 A A Q Q f ace * -^ ma y na PP en that the buds 



'9 o"X fcQ,,6'N& b <^P attached to the cell which gave birth 

 d<> ^^ ^ to them may begin to bud before an 

 <K ^\ d 6 " absolute breaking apart has taken place. 

 ^ e** e** "^ This resu i ts f n the formation of a small 

 ,cQo J $X C *^%""' colony which is made up of a number of 

 y ^^ r^ \? adhering cells. Depending upon the 

 ,, species, the cells appear united two by 



^ g "->P * A**' I?" two ' P ro d u cing a colony made up of 15 

 '0 >5 (3 Q or 20 cells. In general, top yeasts are 



*1 l \ l \ f\ '' fi\ distinguished from the bottom yeasts 

 - p ' by the fact that the former remain 

 j> ^ ^ united to one another, forming little 

 chains, while the latter separate. 



With s - ^ tos and the s enus 



Hansenia we have seen that the cells 



are provided at one or both of the extremities with little projections 

 which give them the appearance of a lemon. It is interesting to 

 observe how budding is accomplished in this yeast. Hansen has 

 shown that the buds always form at the extremity s of the cell. 1 

 The young bud may be apiculate at its free extremity, but it may be 

 oval and give birth to oval buds deprived of points. This may be 

 lost and the property of forming points again assumed. 



(B) Transverse Division 



The genus Saccharomyces presents a form of transition between 

 the ordinary yeasts, which divide by budding, and the Schizo- 

 saccharomyces, in which division is accomplished transversely. In the 

 Saccharomyces division consists of a sort of budding accompanied 

 by the formation of a transverse partition, i.e., a process intermediary 

 between budding and partition. The cells bud generally at their 

 extremities; this is exceptional only when lateral budding is proven. 

 Multiplication is often accomplished in the following manner: The 

 cell elongates and at one end a sort of tube puffs out. This enlarges 

 and is transformed slowly into a bud which remains united to the 

 cell by a wide collar. A wall is formed across this which separates 

 the cells from the bud. 



1 Hansen, E. C. Comp. Rend, des trav. du lab. de Carlsberg, 3, 1881. 



