288 Piih. Pugel Sound Biol. Sta. Vol. 2, No. 51 



Little work has been done dealing with the effect of hydrogen ion 

 concentration on plants, and no literature was found dealing with its 

 effect on Fucus. Gillespie (1918) found the growth of the potato scab 

 (Actinomycoses chromogenus) in media at the exponent 5.2 was slower 

 and generally less vigorous than at less acid exponents. Sometimes the 

 strain succeeded in growing well in a medium which had initially an ex- 

 ponent of 5.2 or even 4.8, but the growth was accompanied by a marked 

 decrease of acidity, and the manner of the growth gave reason to doubt 

 whether even in these cases more than a poor growth can occur in such 

 exponents. 



Cohen and Clark (1919) find in several species of Bacillus that there 

 is a broad zone of pH within which the rates of growth are quite uniform 

 for these short periods during which the increase of viable cells approaches 

 the logarithmic rate. On borders of these zones of pH slight change in 

 the pH produces marked effect upon reproduction. 



Itano and Neill (1919) re2:)ort that Bacillus subtilis germinates at 

 25° and 37° C if the hydrogen ion concentration of the broth is kept be- 

 tween pH 5 and pH 10 but not higher or lower pH values. 



Shelford (1918) found that death among young herring occurred 

 after an exposure of 8 hours when the pH was brought down to 6.825 or 

 iust on the acid side of true neutrality. Lillie, Loeb, Medes and Moore 

 have gotten similar results on sperms and newly fertilized eggs. 



Methods and materials 



Experiments were started in June, 1919, at the Puget Sound Biologi- 

 cal Station to determine if the hydrogen ion concentration had any bearing 

 on the distribution of Fucus. 



The salts used were potassium acid phosphate (KHoPO^), boric acid 

 (HoBOy), potassium chloride (KCl) and sodium hydroxide (NaOH). 

 The first three salts were recrystalized from 3 to 5 times. In all essentials 

 the methods used were those of Clark and Lubs (1917). 



The sodium h3'droxide was prepared from metallic sodium. A piece 

 larger than would be required was placed in a paraffined bottle which con- 

 tained sufficient conductivity water to cover the sodium. The mouth was 

 closed with a paraffined stopper. The solution was poured off and dis- 

 carded when the outer layer had dissolved and approximately the desired 

 amount of the imoxidized sodium remained. At once, and as rapidly as 

 possible, unused conductivity water was poured on the sodium in the paraf- 

 fined bottle and the mouth was closed with a paraffined stopper. After 

 24 hours, when the sodium had thoroly interacted with the water, the de- 

 sired normality of the solution was obtained bv adding a sufficient amount 



