1884. ] . Physiology. 947 
The weakening of the muscles showed itself first in the striped 
part of the adductors, which draw the valves together, and later 
inthe smooth part of the same muscles, which held the valves 
artificially closed for a constantly decreasing period. 
he Venus reticulata, or clovisses, showed the same phenomena; 
the order of extinction of vitality in the different solutions was the 
same; but these mollusks.did not live as long as the preceding 
ones. They succumbed a month after they had been placed in the 
solutions, first in the salts of potash, then in the salts of magnesia, 
and finally in the salts of soda. 
he periwinkles resisted longer than the bivalves, and showed 
a repugnance to the sulphate of soda, in which they lived forty 
S, 
The great buccin succumbs much quicker, as it cannot close its 
shell hermetically like the periwinkles. At the end of twenty- 
four days it died in most of the solutions employed, especially in 
the salts of potash. Its life was prolonged forty-eight hours in 
solution No. 12, in the sulphate of magnesia, and in the sulphate 
of soda, but soon came to an end. 
During all the time these experiments were going on, from 
January 10 to March 15, the palourdes and the periwinkles lived 
in the sea water of the laboratory, the Venus reticulata and the 
Mussels not quite so long, and the buccins only a few days. 
Itisa very important fact, to which we direct special attention, 
that the salts which constitute the sea water and the different so- 
lutions which we employed gave to the water the faculty of dis- 
solving variable quantities of atmospheric air. We proved by 
direct experiments that the solutions of salts of soda retain more 
ar when agitated by it than the solutions of salts of potash. This 
would, therefore, prove that the poisonous character of the salts 
mentioned in our experiments is caused in part by the circum- 
stance that they do not let their solutions become sufficiently 
aerated; their action produced asphyxia. This explains why the 
sulphate of potash and the sulphate of soda, neutral salts to which 
the mollusks are by no means adapted, act so differently upon 
em, the salts of potash killing them quickly and the salts of 
ps Preserving them for some time. 6s 
tom thes ir i onclusions have been 
reached . e experiments the following c 
~ _ L The saline elements of the sea water act very differently on 
mollusks, ; 
2. Every modification in the composition of the sea water finally 
becomes fatal to the life of these animals. ' 
_ 3 Their greater or less resistance depends on their organiza- 
ton. Bivalves resist better than spiral shells, and in these two 
Sroups the results vary according to the different species. 
4. Salts of potash are less favorable to the life of mollusks than 
VOL, XVI, —NO, rx, 60 
