158 
BULLETIN OF THE BUREAU OF FISHERIES 
observations of Nozawa (1929). The reaction which he described was observed to 
occur, as described above, as one of the late stages just preceding gaping. This 
diminished activity is probably typical of an oyster dying from any cause. 
It would be of considerable importance to determine what components of the 
sulphite liquor are the actual toxic agents. It may well be that some substance is 
contained in the liquor in such small quantities as to pass unnoticed in ordinary 
chemical analyses, but which exerts a toxic effect upon the oyster. Such a substance 
(SPECIMEN !.) 
1 
... 4 EXP 25 1 
A.M. JQBP™ | 
J 
i i 
5 6 
r 
(SPECIMEN 2.) 
9 
7 
9 
4 
1 t 
5 6 
l 
7 
APRIL 25 
. , 
(SPECIMEN 3.) 
^ CONTROLS, 
[ 5 (SPECIMEN A) 6 JC . 
i 
. . 7 
i 
4 
1 1 
5 6 
1 
7 
(SPECIMEN 5.5 
UHiM 
s EXP. 24 Is 1 i 
4 5 P.P.™* J. 5 (SPECIMEN 6.) 6 7 
i 
4 
8 9 
5 6 
1 
7 
Figure 38. — Reproduction of portion of kymograph record of experiments Nos. 24 and 25, about two and 
one-half days later than that shown in Figure 37. Specimens Nos. 1 and 2 are dead and the shells are 
gaping open without movement. Specimen No. 5 is open and highly active while specimen No. 6 is 
closed. The controls (3 and 4) show normal activity 
might be extremely dilute and yet toxic. To some substances aquatic animals may be 
highly sensitive. Marsh (1908) found, for example, that silver nitrate killed salmon 
fingerlings in 24 hours at a dilution of 1 to 22 % million. The toxicity of this substance 
as compared with that of sulphite liquor is tremendous. 
That the acid content of the liquor was not responsible for the harmful effect 
was shown by the fact that oysters died in neutralized solutions, as described above, 
as well as by the observations of Galtsoff, as reported in an accompanying paper, that 
