338 SUMMAKY OF CURRENT RESEARCHES RELATING TO 



are often observed which grow upwards into the air, forming a kind 

 of stem of much greater length than thickness. These finger-like 

 colonies are formed in greater number by some yeasts than by others, 

 but their formation depends chiefly on the stiffness of the gelatin and 

 the proximity of the original cell to the surface. When the gelatin is 

 stiff, especially if the surface dries fairly rapidly, the newly-formed cells 

 appear to be unable to displace it, and, in consequence, they grow 

 upwards. After a time, however, probably when the surrounding 

 gelatin has become sufficiently exhausted to be more yielding, the 

 base of the outgrowing colony begins to spread laterally in the medium. 

 Before this stage the colony can be lifted out of the gelatin, leaving^ 

 only a few cells adhering to the latter. The author observed certain 

 differences between the cells in different parts of such colonies. The 

 outer cells of the basal part are elongated, whilst the central ones and 

 those of the upper end are round or oval. The elongated cells contain 

 more vacuoles, and are richer in glycogen than the others. If one side 

 of such an outgrowing colony is illuminated by a lamp, the colony 

 bends over towards that side, owing to the more rapid growth of cells oq 

 the unilluminated side. 



