1921] 
WEBB—GERMINATION OF SPORES OF CERTAIN FUNGI 287 
Pa 4.2, with active acidity of the shavings probably not above 
Px 3.8. This closely approaches Px 3.0, the optimum hydrogen- 
ion concentration in various media, as reported in this paper 
by the writer. 
Hopkins (’21), varying the hydrogen-ion concentration of a 
synthetic medium, the name of which does not appear in the 
published abstract, by means of KH,PO,, K,HPO,, HPO, H,8SO,, 
KOH, and NaOH, found that the amount of growth of Gibberella 
Saubinelii increased with decreasing acidity from Pg 2.5 to 
a maximum at Py 4.0-4.5. It then decreased to a minimum at 
Py 5.0-5.5 and rose again to a second maximum, but the high- 
est point was not determined. Conidial germination of the same 
organism also showed a double maximum. A Fusarium isolated 
from scabby wheat, but not proved to be Gibberella, exhibited 
a similar depression in the growth-acidity curve. These rela- 
tions agree well with those established in this paper. 
Armstrong (721), using a modified Richards’ solution contain- 
ing sulphur supplied as Na,S,0, and as MgSO,, determined the 
growth relations of certain fungi as influenced by hydrogen-ion 
concentration. Within the experimental range Py 3.0-7.1, he 
found that Aspergillus niger produced maximum growth with an 
initial reaction of Pg 5.5-5.9, Penicillium cyclopium at Pu 4.1- 
4.5, and Botrytis cinerea at Pg 4.1-5.9. Inhibition of growth, 
in all cases, occurred at Py 3.0, and in the case of Botrytis cinerea, 
distinctly retarded and suppressed growth was evidenced at 
Py 7.1. Changes in reaction of the liquid culture media in- 
variably took place during growth of the organisms, and, in 
addition, reversions in the reaction frequently manifested them- 
selves, the nature and degree of such changes and reversions 
varying with the organism, the medium, and the initial hydrogen- 
ion concentration. 
Karrer (’21), growing certain fungi on Czapek’s solution with 
soluble starch as the source of energy, accumulated interesting 
data with respect to the reaction of the medium. Fusarium 
produced no growth at Px 2.0 and the limit on the alkaline side 
extended beyond Pg 9.2. Colletotrichum Gossypii gave a fair 
quantity of mycelium from between Py 3.0-4.5 to above Pu 9.2. 
Penicillium italicum displayed a more limited range for favorable 
