SPOROBOLOMYCES 



177 



normal manner. The drop excreted from the spore-hilum may grow 

 abnormally large, run up the side of the spore and more or less 

 enclose the spore, and then the spore is not discharged from its 

 sterigma. The drop may then dry up and, later, a second spore 

 may be developed on the end of the same sterigma. Then there are 



Fig. 86. — Apparatus used for observing the development 

 of yeast colonies of Sporobolomyces roseus ; the Petri 

 dish a contains malt-agar b and is covered almost 

 completely by a split glass plate c c and by a rectan- 

 gular glass plate d. Scattered in the agar are several 

 yeast colonies e, and to the edge of one of them the 

 objective of the microscope is applied, as shown at /. 

 Drawn by A. H. R. Buller and Ruth Macrae. Reduced 

 to about two-thirds the natural size. 



two spores sticking together on the end of one and the same sterigma. 

 This is clearly an abnormality due to unsuitable atmospheric 

 conditions. 



To provide ventilation and, at the same time, to prevent undue 

 desiccation of the culture medium and yeast cells whilst observations 

 were being made with the high-power objective, the following 

 method was employed. 



Sporobolomyces roseus was grown on malt-agar in a Petri dish in 

 the usual way (Fig. 86, e). Spores were sh'ot upwards from the older 



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