BLOOD OF FRESH-WATER MUSSELS 
535 
in their marsupia. In some cases glochidia, from the marsupia of mussels which had 
been carried successfully for several days in solutions of calcium salts, were so re- 
duced in sensitivity that 10 per cent sodium chloride solution was required to excite 
these glochidia to the closing response, although the glochidia appeared otherwise to 
be in splendid condition. 
Blood sugar and blood ash determinations were made on the blood of mussels from 
both the calcium-salt series and the sodium-salt series. In both groups the blood 
sugar was found to vary within the same limits as those defined for the normal ani- 
mals, but the blood ash in both sodium and calcium series was higher than in normal 
mussels. The increase in blood ash shows that in the calcium and sodium series the 
mussels during the period of high-blood specific gravity, actually had more inorganic 
solids in their blood. Whether this rise in ash content was due to the loss of water 
from the blood, thereby producing a concentration of the salts already in the blood, 
or whether this high ash content represented a movement of salts into the blood, was 
Figure 13. — Blood specific gravity of mussels living in solutions of calcium salts. Black circle, 1 per cent calcium chloride; 
circle, 0.5 per cent calcium chloride; scored circle, 0.25 per cent calcium chloride; scored black circle, 0.1 per cent calcium 
chloride 
not determined. In either event, however, the tissues of the animal were subjected 
to a blood of higher salt concentration. 
EFFECTS OF EXPOSURES TO AIR 
AT ORDINARY TEMPERATURES 
Sudden changes in stream level may leave fresh-water mussels stranded out of 
water, but ordinarily the low-water stages come so slowly that littoral forms like the 
slough sand-shell, Lampsilis fallaciosa, and species which move in and out of shallow 
water as the yellow sand-shell, Lampsilis anodontoides, may easily keep ahead of the 
receding water. For mussel species living on bars in deeper water, exposure to the 
air is a more or less remote possibility in their normal-life activities. 
The work attendant on propagation of mussels has made it necessary to expose 
mussels to the air, and often these animals are shipped long distances without water. 
To determine the effect of removal from water and exposure to air on the mussel, 
using the blood as an index, a series of 50 mussels was taken directly from the river to 
the laboratory, wiped dry and spread out separately so that there could be no accumu- 
lation of water below or around the mussels. Every opportunity was offered, there- 
fore, for these mussels to “dry out” at room temperature. 
