BLOOD OF FRESH-WATER MUSSELS 
539 
and each animal held at 20° C. for six hours beforelthe initial blood sample was 
taken. The blood samples were drawn directly from the heart, as in previous tests, 
with a fine dental needle mounted on a Leur syringe. 
By adding ice to the water in the jar, the temperature of the animal as deter- 
mined from the pericardial fluid, was reduced at the rate of 5° C. in 30 minutes. 
After the mussel’s body temperature had been reduced to 0° C. and the last sample 
taken, the mussel was slowly returned to a temperature of 15° C. to 20° C. where 
it was held until the following morning (approximately 24 hours after the first sample 
was drawn), when samples were drawn again during a second reduction of body 
temperature similar to that of the first day. In the case of mussel C, samples were 
taken at the beginning and at the end of a third temperature reduction during the 
third day. After the last samples were taken each mussel was held at room tem- 
perature for 24 hours as a check on its condition. None of the mussels of this series 
died during the 24 hours following the termination of these tests. 
The data from this series are given in Table 18. 
Table 18.- — i Specific gravity of the blood of fresh-water mussels at various temperatures 
Individual 
20° C. 
15° C. 
o 
p 
5° C. 
d 
o 
1. 0022 
1. 0012 
1. 0016 
1. 0022 
1. 0010 
1. 0017 
1. 0022 
1. 0021 
1. 0020 
1.0012 
1. 0012 
1.0016 
1. 0014 
1. 0018 
1. 0005 
1. 0008 i 
1. 0010 
C-J second day 
1. 0005 
1. 0005 
.0015 
1. 0021 
1. 0018 
1. 0010 
1. 0015 
1.0010 
1.0012 
1. 0014 
1. 0012 
\second day - - . 
1. 0015 
1. 0017 
1. 0021 
1. 0016 
1. 0019 
The figures given in Table 18 show that the specific gravity of the blood did not 
rise to the levels attained by the blood from the mussels of the ice series in which 
no precaution was taken to prevent undue loss of water by the mussel. In fact, there 
was little or no concentration of the blood, as measured by the specific gravity, in 
these floaters which were protected from air currents and loss of water, although 
they were lowered to zero centigrade. 
The changes in the blood specific gravity of the mussels when held in air are 
evidently a matter of water loss to a large extent, as the mussel seems to have no 
way to maintain the blood concentration level when water is removed from a large 
portion of the body. The changes in the alkalinity were not evident in the blood 
until the animal became moribund as the result of the water loss. 
SUMMARY 
Blood from 27 species of North American fresh-water mussels was analyzed and 
the values of the various characteristics and constituents of normal fresh-water mussel 
blood determined. These values have been summarized in Table 19. 
Table 19. — Summary of the characteristics and constituents of normal fresh-water mussel blood 
Mini- 
mum 
Average 
Maxi- 
mum 
Mini- 
mum 
Average 
Maxi- 
mum 
SDecific eravitv _ _ 
1. 0003 
1. 0026 
1.0078 
0. 0087 
0 0270 
0 1060 
Total solids.. 
...per cent.. 
.3436 
.4260 
.4965 
pH 
7. 4 
7.9 
8.5 
Total ash__ 
.do 
. 1256 
.1539 
.2820 
Blood gases: 
Organic material-- 
do 
.1190 
.2721 
.3145 
Oxygen volumes per cent.. 
. 16 
.39 
.89 
Blood sugar 
milligrams.. 
7 
32 
93 
Carbon dioxide do 
.09 
.43 
.81 
Sodium chloride 
Der cent 
.0310 
. 1090 
.2950 
1. 08 
1. 34 
1.80 
