256 BOTANICAL GAZETTE [OCTOBER 
clusively for the pure cultures. These media had the following 
composition: 
MEDIUM I 
eo sy 5 5 a ec ee egw wed 100.0 CC. 
ac ct ens etstive gh 4s 30.0 gm. 
es ok cbecccccclndvese 2.0 gm. 
Monopotassium phosphate.................0..000% 0.2 gm. 
er RBs or is an Foe eS ee ieee et rae 0.2 gm. 
I ge ce as oo deen 0,02 gm. 
ne cy sc ss os eeu bh + os Trace 
MEDIUM 2 
MEDIUM 3 
uk. OS Oot ae 100.00 CC 
Peart ee ee 4 is ad's o)k caw os -0O gm 
Monopotassium phosphate............ (M/r00) 0.136 gm. 
Calcium nitrate........ eet aries. (M/ roo) 0.164 gm. 
Magnesium sulphate................. (M/1000) 0.012 gm. 
RN ks rk ss Sh ence « (M/t0oo) 0.270 gm. 
Medium 3 was not quite so transparent as medium 2. How- 
ever, as previously noted, the fungi studied seemed to develop 
more characteristically on the latter. The acidity of media 1 and 
2 was tested by the method in common use among bacteriologists 
(14), described by Duccar (32). Medium 1 gave an acidity of 
80, according to FuLter’s (34) scale; medium 2 gave 20. The 
inhibiting effect of the gelatin medium on bacteria is thought to 
be due to its rather strong acidity. The quantities of the mineral 
constituents of these media were based on some studies on “opti- 
mum media” carried on in this laboratory, where it has been found 
that the optimum quantities, especially of the nitrate, are much 
low the quantities generally recommended. The same has been 
confirmed in this investigation. 
METHOD OF SAMPLES, PLATINGS, AND ISOLATIONS 
The method of taking the soil samples was a slight modification 
of that used by Kine and DoryLanp (35), at the Kansas Experi 
ment Station, in bacteriological work. The sampler consists of @ 
steel tube, ro cm. long and 1 cm. inside diameter, together with a 
