6 BULLETIN 1053, U. S. DEPARTMENT OF AGRICULTURE. 
tubes are formed, and the spore is always very conspicuous in the 
thallus. The germ tubes of Fomes roseus have been more vacuolate 
than those of the other species. 
The spores of all species' germinate readily upon all nutrient media 
and upon red spruce (PI. V, fig 10, for. Lentinus lepideus). In water 
the results were as erratic as those reported by other workers with 
spores of basidiomycetes. The spores germinated in tap water, al- 
though the proportion ranged from less than 1 to 55 per cent in dis- 
tilled water germination took place occasionally (PL III, fig. 2, for 
Lenzites sepiaria). The rate of germination was usually low, 
although sometimes as high as 50 per cent. Even with fresh spores 
germination could not always be induced in distilled water. 
EFFECT OF TEMPERATURE UPON THE GERMINATION OF THE BASIDIOSPORES. 
In these studies both percentage and rapidity of germination have 
been noted. It is interesting to know the rate at which these spores 
germinate, but of the two criteria percentage would be likely to give 
the best indication of the effect of various environmental conditions. 
From the point of view of infection of structural timbers, if a large 
percentage of spores will germinate over a wide range of temperatures 
it makes little difference whether it takes three or four days for 
them to germinate at 10° C. (49° F.) or only 16 hours at the optimum 
rate of germination. The chances for infection, however, are some- 
what greater at the optimum temperatures, because of the somewhat 
larger number of spores capable of germinating. The percentages 
given herewith have no absolute value, either for the individual 
species or for purposes of comparison between species. It is possible 
that spores collected from different fruit bodies of the same species 
of different degrees of maturity, from different climatic conditions, 
and under different conditions of casting might give varying per- 
centage values. It is certain that age is a factor. Hence, that one 
species should give 75 per cent germination at the optimum tempera- 
ture and another onty 40 per cent does not mean that the spores of 
the one are inherently more vigorous than those of the other. In 
the data presented germination is taken to consist in a germ tube at 
least as long as the swollen spore. The data for the effect of tem- 
perature upon germination are given in Table 1 and in figure 1. 
For Lenzites sepiaria with certain variations tests showed that 
between 12° and 40° C, (53° and 104° F.) there was little difference 
as to the effect of temperature upon the percentage of germination if 
the time element was disregarded. The optimum for rate of germina- 
tion was between 32° and 36° C. (89° and 97° F.), an optimum 
somewhat lower than that obtained by Falck. At 40° C. (104° F.) 
the results varied with the age of the spores. Those a few months 
