146 Papers from the Marine Biological Laboratory at Tortugas. 



Table V. — Summary of results of cross-fertilization in sea-water of decreased 



alkalinity. 



[Hydrochloric acid. Number of plutei studied in each fertilization, 50. Temperature, 29°-29.s° C] 



Year. 



1909 

 (i) 1910 



(2) 1910 



(3) 1910 



(4) 1910 

 (s) 1910 



Cross. 



Tox. 9 



moTI P^rf^^* 



than one! ^j^^^; 



rod. I '*^'^ ^°'^^- 



Further data: 



1909. Eggs fertilized in 400 c.c. sea-water+ 10 drops j*], HCl. 



(i) 1910. Eggs fertilized in 500 c.c. sea-water+ 15 drops ~ HCl. 3 days. 



(2) 1910. Eggs fertilized in soo c.c. sea-water+ 15 drops it HCl. 4 days. 



(3) 1910. Eggs fertilized in 500 c.c. sea-water+ 15 drops S'^ HCl. 5 days. 



(4) 1910. Eggs fertilized in 500 c.c. sea-water+30 drops J\y HCl. 2 days. 



(5) 1910. Eggs fertilized in 500 c.c. sea-water+30 drops ^^ HCl. 2 days. 



Table VI shows that the effect of the addition of the acid has been 

 to swing the dominance in the Hipponoe S X ToxopneustescJ' cross to the 

 Toxopneustes side: 



Table VI. — Summary of results of cross-fertilization in sea-ivater of decreased 



alkalinity. 



[20 drops iL acetic acid to 400 c.c. sea-water. Number of plutei studied, 50. Temperature, 29° C] 



