14 Mason: The Yeast-Fungi in Nature. 
By the time that fruits are fully ripe the yeasts have devel- 
oped large colonies. Then come Autumnal winds, by means of 
which, masses of cells are swept from their summer habitat to 
become for a time part of the floating populace of the atmos- 
phere. Finally they settle down to the soil where they are 
afterwards joined by those cells which, having so far escaped 
removal by the winds, remain on the fruit only to be washed 
down by the more searching action of the rain. 
Thus, by wind and rain and to some small extent by the 
agency of insects and birds, the yeasts are conveyed to their 
secondary breeding place, the soil. This situation, although 
not of primary importance for purposes of reproduction, is 
the principal habitat of the Saccharomyceteae ; a fact which has 
been demonstrated by Hansen, Wortmann and Miiller-Thurgau. 
Hansen, who devoted the greater part of a long life to the study 
of the yeast-fungi, in investigating this aspect of their life- 
history, made analysis of hundreds of samples of soil from 
various points right across Europe. The results of this work, 
besides proving the soil to be the chief habitat of the Saccharo- 
mycete@, threw valuable light upon their distribution with 
regard to the nature and environment of the soil in which they 
occur. For instance, in one series of 200 analyses true yeast 
fungi were found in 67 per cent. of samples under fruit trees 
and fruit bushes ; in 30 per cent. of those from under deciduous 
and coniferous trees and only 19 per cent. in samples of soil 
from distant fields.* 
On the surface and in the soil even to a depth of 12 inchest 
yeasts spend the winter in safety, during which time repro- 
duction takes place only to a small extent and then mostly 
by means of spore-formation, a characteristic feature of the 
true yeast-fungi. This process, as well as increasing their 
numbers, provides an added security (the spore being able to 
stand adverse conditions much better than the parent cell) 
and at the beginning of Spring when windy weather is again the 
rule, the cells or their spores are once more ready for trans- 
ference to their primary breeding places, the fruits. 
The bark of various trees is also a common habitat of yeasts. 
In some instances vast colonies of these organisms are found 
in viscid, slimy masses to so great an extent as to be considered 
a disease. A good many such cases are recorded in continental 
literature, and under the title ‘ Slime-flux,’ this condition is 
referred to in the ‘ Text Book of Plant Diseases,’ by Massee. 
No instance, however, of its occurence in this country is given ; 
an omission, no doubt, on account of its relative non-import- 
ance from a phytopathological point of view; but I have met 
* Lafar’s (Salter) Tech. Mycology, II., p. 254. 
t+ Muller-Thurgau. 
Naturalist, 
