Papers from the Marine Biological Laboratory at Tortugas. 



47 



water. The dotted curve applies to 0.057 rnolecular MgCl2. The crosses 

 show the effects of adding 0.9 molecular dextrose to sea-water, and the black 

 circles show the effects of increments of distilled water added to sea-water. 



100 





.5 



.6 .7 .8 .9 



Relative Concentration of Na, Ca, and K. 



Fig. 9. 



1. 



Table 10 shows the decline in rate of nerve-conduction in 7 subumbrella 

 rings of Cassiopea in sea-water diluted with a solution composed of 0.057 

 molecular MgC^ + 0.78 molecular dextrose. 



> Only two rings were tested in this solution and they both gave relative rates of 94. This rate is prob- 

 ably too low to be typical, and therefore I have rejected the results obtained from these two rings and 

 omitted them from the table. 



By another method, which was tried at Tortugas in 191 1 and 1912, the 

 normal osmotic pressure was maintained by adding to the sea-water a 0.4 

 molecular solution of MgCl2 in distilled water. This causes a dilution of 



Table ii. 



