398 GEOGRAPHICAL DISTRIBUTION OF FUNGI 



The constant occurrence of lime granules as a constituent part 

 of the fructifications among species of Badhamia, Craterium, 

 Diderma, Diachea, Didvmium, Fuligo, Leocarpus, Alucilago, and 

 Phvsarum and their absence in others, for example, among jComa- 

 trichia and Stemonitis, are not without significance. Carr (1939) 

 reported that 90% of the species on sandstone soils in a region in 

 Virginia are "non-lime species" and 88% of those on limestone 

 soils in this same region are "lime species." From comparison of 

 collections made in Sweden with those made along the border 

 between Bolivia and Argentina, Fries (1903) concluded that lime- 

 containing species predominate over non-lime-containing species 

 in the tropics, but that the reverse is true in temperate regions. 

 That regional distribution is not determined entirelv by the cal- 

 careousness of soils is borne out by the findings of other collectors, 

 as Martin (1940) has indicated. 



Thorn and Raper (1930) found that numerous species may be 

 isolated from arable soils, where they occur in the plant debris 

 and litter. Abundant evidence is at hand to show that they sub- 

 sist upon various fungi and bacteria that decompose plant re- 

 mains. The influence of food in distribution is further evidenced 

 by the rather constant occurrence of certain species among mosses, 

 of others on decaying coniferous leaves, and of others on decaying 

 leaves of hardwoods. 



Some slime molds may develop well above the ground. Smith 

 (1931) collected Lycogala fusco-flavum and Mucilago spongiosa 

 var. solida 8 to 10 feet up on exposed, heart-rotted trunks of Cot- 

 tonwood. The plasmodium of some species, such as Phy sarin n 

 cinereum, may climb upon blades of grass or other vegetation 

 immediately before becoming transformed into sporangia. 



Plasmodiophora brassicae is now essentially world-wide in dis- 

 tribution. Its wide host range among cruciferous species and its 

 preference for acid soils constitute the important factors that have 

 contributed to this broad range. Evidence indicates that for over 

 200 years market gardeners have contended with club-root disease, 

 which it causes on cabbage, radishes, and turnips. In Europe it is 

 most destructive in the northern portions of the continent. It has 

 been reported from nearly all parts of the United States and from 

 Alaska and Canada. A monograph on Plasmodiophorales by 

 Karling (1942) contains an extensive bibliography on the range 

 of this organism and on other features. 



