294 Studies in the F/ii/.siolo(ji/ of Fertilization 



2. Efied of an increase in the H-ion concentration. 



In the first series of experiments equal quantities (given in 

 Table XXXVI) of a Ciona sperm-suspension were pipetted into 

 (1) 100 CO. normal sea-water, (2) 100 cc. acid sea-water, the constitution 

 of which is given below. 10 cc. of each of the liquids (1) and (2) were 

 then poured on to separate approximately (M|ual amounts of eggs of 

 another individual Ciona. Exj). 1 was made for two, and Exp. 3 for 

 three different strengths of sperm. 



The acid sea-water.s (2) were made up as follows: 



In Exp. 1, •2cc. N/10 HCl added to 100 cc. .sea- water. 

 In Exp. 2, ■:] 

 In Exj]. 3, 1 



Each of these solutions was tested previously, using the colorimetric 

 method elaborated by Sorensen (4). The addition of eight drops of 

 a-Naphtholphthalein to test-tubes containing 10 cc. of the liquid gave 

 the following colours: 



Normal sea-water Green. 



Acid water of Exp. 1 V. light gi-een. 



Ditto of Exp. 2 Light greenish briiwn. 



Ditto of Exp. 3 Pink. 



The results of these experiments are given in 'I'able XXXVI. 

 TABLE XXXVL (.10.14.3.) 



Normal water Acid water 



Exp.i. K/r \ f- "''™ ■ ° "^ 



'• ( 20 cc. sperm ... 100 8 



Exp. 2. C/d 5 cc. sperm ... 3 



f -Ct cc. sperm ... 45 



Exp 3. A/b I 2 cc. sperm ... 97 



' 5 ce. sperm ... 100 



In the first part of Exp. 1 too little sperm was added to give a com- 

 parison. In the second part of the same experiment the effect of the 

 acid water on the sperm was to cause a great fall in the fertilization 

 percentage. In Exps. 2 and 3, of which Exp. 2 was made with a slightly 

 greater and Exp. 3 with a con.siderably greater concentration of H-ions 

 than Exp. 1, the effect of the acid waters on the sjxn-matozoa was to 

 inhibit fertilization completely. 



