[5] BIOLOGICAL ACTION OF SEA-WATER UPON ANIMALS. 70o 



able action of salts of soda on the preservation of life in marine ani- 

 mals ; for forty days the palourdes lived in this mineral water ! 



It was in the sulphate of magnesia and the sulphate of soda that life 

 was sustained longest, the latter excelling the former. On the 12th 

 March I tasted some of the Venus decussata which had been kept in sul- 

 phate of soda for sixty days, and found their flavor excellent and with- 

 out any trace of a bitter flavor. This observation might prove useful 

 in alimentary economy, as the palourde is a highly prized shell-fish, and 

 sulphate of soda can be bought cheap. 



It is a fact worthy of remark that it was only in the solutions of sul- 

 phate of soda and sulphate of magnesia that green algae commenced to 

 make their appearance at the end of sixty days. The conditions favor- 

 able to marine animal life are then apt to develop vegetable life. There 

 is nothing surprising in this parallelism, but it receives from the pres- 

 ent circumstance a curious confirmation. One singularity appears: 

 the solution of chloride of sodiun) (impure marine salt) did not sustain 

 life as long as the solutions of salt of magnesia and sulphate of soda, 

 and yet salt is an essential element of the sea- water. This proves that 

 the mollusks are adapted, not to pure salt, but to that peculiar mixture 

 which constitutes the natural sea- water; and that the secondary ele- 

 ments, as regards their quantity, play an important part. This gives 

 us reason to suppose that the accidental modifications of the water of 

 the sea during the different geological periods must have had a great 

 deal to do with the extinction of various species. 



The venus remained closed in most of the solutions, the nature of 

 which they doubtless learned to know by opening their valves a very 

 little. Meanwhile they occasionally put their siphons outside the shell, 

 for instance in the sulphate of magnesia and in the sulphate of soda. 

 In the solution of chloride of sodium and in the sea- water they had their 

 siphons out nearly all the time. 



The palourdes can live for more than a month in the air in a cool 

 place. For about twenty days they remain shut; later they open their 

 valves and protrude their siphons. At the least touch they draw them 

 in and close their valves. Then comes the moment when the striped 

 muscles which bring the valves together have no longer the strength 

 to do this, although the smooth muscles which retain them will still do 

 so, when one closes the valves. In all the solutions in which these 

 mollusks have lived these same phenomena could be observed. 



The weakening of the muscles showed itself first in the striped part 

 of the adductors, which draw the valves together, and later in the 

 smooth part of the same muscles, which held the valves artificially 

 closed for a constantly decreasing period.* 



The Venus reticulata, or clovisses, showed the same phenomena; the 

 order of extinction of vitality in the different solutions was the same; 



*See De V Anergic et de la structure muficulaire chez les mollusques ac^phalea. [On the 

 energy and muscular structure of the acephala.] By J. B. Baillifere, Paris. 

 S. Mis. 110 48 



