1921] 
MATSUMOTO—SPECIALIZATION IN RHIZOCTONIA 35 
also a 2 per cent dextrose, and this was heated for half an hour 
in an autoclave. Erlenmeyers of 25 cc. capacity were then 
inoculated with the 6 strains and incubated at 23° C. for 3 weeks, 
with the following yields of mycelium: P1, 0.54 gm.; P4, .18 
gm.; P7, .015 gm.; B1, .80 gm.; H, .056 gm., and B3, a negligible 
amount. 
A marked hydrolysis of the albumen occurred in P1 and H, 
with the larger growth quantities. 
GROWTH OF THE Six STRAINS IN RELATION TO H-ION CoNcEN- 
TRATION} 
. The importance of the reaction of the culture media as a 
physiological factor with microérganisms is well recognized, 
consequently the literature dealing with this problem is rather 
extensive. Adequate reviews of the literature dealing with the 
subject were recently given by Webb (19), and it is unnecessary 
to include such reviews in this paper. Concerning the influence 
of acid and alkali on the growth of these fungi, however, Duggar 
(99), in an early paper referring to remedial measures, made the 
following statement: “The use of an alkali as a preventive 
might be logically suggested knowing the rapidity with which 
the fungus grows on acidulated nutrient media." Peltier (19), 
however, in his study on carnation stem rot stated: ‘‘The results 
showed that Rhizoctonia can grow on medium which is, within 
reasonable limits, either acid or alkaline in reaction." No 
definite determination of the effect of hydrogen ion (or hydroxyl 
ion) concentration upon the rate of the mycelial growth of these 
fungi has been made. 
In my investigation, although rather preliminary in nature, 
the attempt has been made to determine the critical and opti- 
mum H-ion concentration, such as observed by Meacham (^18) 
in mycelial growth of four wood-destroying fungi, or by Webb 
(19) in the germination of the spores of certain fungi; likewise 
I have endeavored to ascertain whether there is any speciali- 
zation of strains in this respect. 
In my earlier studies during this investigation the reactions of 
the various natural decoctions were designated by Fuller's scale. 
That this is unsatisfactory is now well known (Duggar and 
associates, 17), so that in the later studies the method of hydro- 
