STUDIES IN THE PHYSIOLOGY OF THE FUNGI 



X. Germination of the Spores of Certain Fungi in Re- 

 lation to Hydrogen Ion Concentration 1 



ROBERT W. WEBB 



Rufus J. Lackland Fellow in the Henry Shaw School of Botany of 



Washington University 



Introduction 



The hydrogen ion concentration of culture media or solutions 

 has come to be regarded in recent years as one of the most im- 

 portant factors influencing physiological phenomena. A volum- 

 inous literature is found dealing with the toxic properties of H 

 and OH ions in a general way, but the earlier investigators, like 

 many of the later ones, were handicapped by lack of methods, or 

 experience with methods, for the direct determination of hy- 

 drogen ion concentration. With such limitation in technique, 

 conductivity data have frequently been employed in the in- 

 terpretations made. This method is, however, inapplicable 

 when other solutes are introduced, and the presence of strong 

 buffers, whether inorganic or organic, would render most dif- 

 ficult any computation of active acidity or alkalinity. 



Some of the questions which are unanswered are : What is the 

 effect of hydrogen ion concentration upon the rate of germina- 

 tion of the spores of certain fungi, or, what is the range within 

 which the most favorable germination occurs? Such questions 

 suggested the desirability of conducting the investigation re- 

 ported in this paper, and the scarcity of definite literature dealing 

 with this particular phase has been one of the greatest incentives 

 to the pursuance of the problem. 



Review of Literature 



Clark ('99) seems to have been one of the pioneer workers on 

 the toxicity of acids, alkalis, oxidizing agents, and salts of the 

 heavier metals, towards the growth of certain fungi. Using the 



'An investigation carried out at the Missouri Botanical Garden in the Graduate 

 Laboratory of the Henry Shaw School of Botany of Washington University, and 

 submitted as a thesis in partial fulfillment of the requirements for the degree of 

 master of arts in the Henry Shaw School of Botany of Washington University. 



Ann. Mo. Bot. Gabd., Vol. 6, 1919 



(201) 



