It is not as yet possible to give a sharp systematic delimitation to the anascosporous yeasts. These are generally understood to be yeastlike fungi which have permanently lost their capacity to produce ascospores. It is not always easy, however, to determine when this has occurred.
Before studying any kind of yeastlike organism one has to be sure of the purity of the strain, for which Raulin's1 solution is valuable. Several loopfuls of the culture are inoculated into this medium and incubated for three or four days at 37 C. or at room temperature, after which a loopful is taken from the Raulin solution and a pour plate made with 2 per cent dextrose agar. This is incubated at room temperature for two or three days, and an isolated colony is fished and streaked on a dextrose agar slant. The purity of the growth on the slant is later determined