168 



Puget Sound Marine Sta. Pub. 



Vol. 1, No. 14 



caused cessation of development in the eggs of a European sea urchin. 

 Slight increase in alkalinity causes an increase in growth and cell divi- 

 sion, while very small additions of acid inhibited these processes. Whit- 

 ley (28) found further that the same relations obtained in the case of the 

 developing eggs of plaice. It is difficult to say how much the addition 

 of alkali and acid modified the concentration of hydrogen and h3'droxyl 

 ions in the case of the experiments of these investigators or my own, 

 because the determination on ion concentration requires special methods. 



Table 6. Shoxving comparative resistance of echinoderms, mollusks and 

 barnacles from different depths, to fresh water. 



Scientific and Common 

 Name 



Balanus balanoides L. 



Shallow water barnacles 

 Balanus aquilla Spil. 



Deep water barnacle . . . 

 Mytilus edulus Lin. 



Shallow water mussel.. 

 Modiolus modiolus Lam. 



Hairy mussels 



Leptasterias hexactis Stlmp. 



Six-rayed star 



Henrlcia sanguinolentiaMull. 



Blood star 



Crossaster papposus Lin. 

 Rose star 



Pteraster tessalatus Ives. 

 Cus'-''^n star 



Gorgonocephalus eucnemis 

 (M. & T.) Basket star. 



Acmaea patina Esch. 

 Limpet 



Acmaea relta Esch. 

 Limpet 



Acmaea mitra Escli. 

 Limpet 



Calyptraea fastiglata Gld. 

 T.imr'Pt 



3 3 p 









 20-40 

 0-2 

 0-125 





 0-1000 



10-100 



30-80 

 30-80 



5 

 5 



.5 

 5 

 3* 



3* 



I 



I 3 

 1 

 I 1* 



1 







?x 



32 hr. 

 32 hr. 



I 20-40 I 



I I 



I 0-2 I 168 hr. 



125 I 168 hr. 



2940 min. 



I ? I 315 min. 



I I 



I 20-40 I 540 min. 



1 I 



I 20-40 I 100 min. 



315 min. 



2* I +2 



I 



I 

 80 I 45 min. 



I 

 80 I 100 min. 



100 I 25 min. 



100 I 45 min. 



I 



I 113 min. 



I 



I +2 



5* I 



I 113 min. 



113 min. 

 85 min. 



■a (D - 



o3 S, 



Alive 



5 dead 



All alive 



3 dead 



All dead 



Alive 



Dead 



Alive 



Dead 



Alive 



Dead 



PartialH- 

 recovered 



died 

 Dead 



1 dead 

 1 dead 



Both dead 

 All dead 



♦Several additional experiments performed, part with similar results and 

 part w^ith a view^ to determine an exposure which would be likely to give 

 differential results. 



