1916] i 
GILMAN—CABBAGE YELLOWS 55 
-vaporarius spumarius, and Verpa bohemica all have а mini- 
mum temperature for growth of about 3°C.; M erulius sil- 
vester, M. sclerotiorum, and Polyporus vaporarius spumarius 
have an optimum of about 25°C., while the optimum for Меги- 
lius domesticus and Verpa bohemica is at 22° С. Their шах- 
ima are all at about 30°C. It was noted that these tempera- 
tures correspond very closely to those of Phycomyces nitens 
and Mucor Mucedo, as determined for comparison, although 
each species has a rate of growth that is constant for a given 
temperature (other factors being equal) and characteristic of 
that species. 
With the exception of the genus Fusarium, Ше preceding 
covers the important work that has been done on the tempera- 
ture relation of the parasitic fungi, as far as could be ascer- 
tained. It will be readily seen that the relation of tempera- 
ture to the attack of a parasite is a complex one and depends 
entirely upon the individual diseases under observation. 
To take up now the relations of temperature to diseases 
caused by Fusarium, Jones (’08) stated in his observations 
on the damping off of coniferous seedlings, caused by a mem- 
ber of that genus, that the trouble was facilitated by high 
temperatures. He was confirmed in this by Gifford (211), 
working оп Ше same trouble. Wollenweber (713), however, 
was the first to show this relation in the case of the wilt dis- 
eases caused by Fusarium. He pointed out that these dis- 
eases occur most severely in the warmer climates, especially 
in the tropics and subtropies, but noted the cabbage yellows 
as an exception to this general rule. Previously, Wolf (710) 
had noted, in the case of the wilt disease of pansy (Fusarium 
Violae), that the trouble was found only in July, and then 
only when the beds in which the plants were growing had been 
heavily covered with fresh horse manure, both of which facts 
suggest a dependence of the fungus on high temperature. 
This author made no mention of temperature, nor were any 
experiments on this relation reported. 
Orton (713, 714) in discussing the potato plant and its rela- 
tion to disease has shown that in this instance Wollenweber’s 
hypothesis held true, the Fusarium wilt having a southern 
