SPOROBOLOMYCES i 79 



progeny develop a colony of very numerous yeast cells before any 



Fig. 87. — Sporobolomyces roseus. At u-m, successive stages 

 in the development of a yeast colony from a spore in 

 the course of 22 hours on the surface of malt-agar ; 

 a, a spore which fell on the agar ; b, after 1 hour 10 

 minutes ; c, after 1 hour 40 minutes ; d, after 3 hours 

 10 minutes ; e, after 4 hours 30 minutes ; /, after 5 

 hours ; g, after 5 hours 30 minutes ; h, after 5 hours 

 45 minutes ; i, after G hours 15 minutes ; j, after 8 

 hours ; k, after 8 hours 45 minutes ; /, after 10 hours ; 

 and m, after 22 hours. The arrows in ra point to yeast 

 cells which have developed a sterigma and are about to 

 produce a spore. At n three of the lower cells of the 

 colony m are represented semi-diagrammatically in 

 side view as they would have appeared about 2 hours 

 after m was drawn ; the cells are partly embedded in 

 agar ; the sterigma now bears a mature spore like that 

 shown at a ; the spore is aerially situated and shortly 

 would be discharged. The right-hand cell is shrunken ; 

 it seems to have died between the stages k and m. 

 Total time from stage a to stage n is 24 hours. Drawn 

 by A. H. R. Buller and Ruth Macrae. Magnification, 

 75(i. 



of the yeast cells produce sterigmata and spores, and spore-production 

 takes place in what may be considered as a normal manner. The 



