154 
BULLETIN OF THE BUREAU OF FISHERIES 
mens in this respect will suffice to show the progressive departure of the sulphite- 
treated oysters from the normal. Nozawa (1929) said that while the periodic closures 
of the shells occur in the normal Japanese oyster at about six per hour, after reduction 
of dissolved oxygen to 2 to 3 cubic centimeters per liter the frequency of shell move- 
ments is much reduced, as the time required for opening and closing becomes longer. 
(SPECIMEN I.) 
PM. Z I 3 i 
l0RR J (SPECIMEN 2.) 
'y 
1 i I 
2 3 4 
APRIL 18 
(SPECIMEN 3.) 
CONTROLS 
(SPECIMEN 4.) 
(SPECIMEN 5.1 
LXR 24. I 
SHE™ J 
1 9 I 
2 3 4 
(SPECIMEN 6.) 
8 I i 
2 3 4 
Figure 34. — Reproduction of portion of kymograph sheet showing records of shell movements of oysters 
used in experiments Nos. 24 (5 parts per 1,000; specimens Nos. 5 and 6 at bottom) and 25 (10 parts 
per 1,000; specimens Nos. 1 and 2 at top). The middle two records were made by the controls 
(specimens Nos. 3 and 4). Intervals of one hour are indicated. At 2.20 p. m. the liquor solution was 
started running into the experimental chambers. Note the more frequent shell movements of specimens 
Nos. 1, 2, 5, and 6 immediately thereafter. See Figures 35 to 38 
The primary effect of sulphite liquor solution on the oyster is just the reverse. 
It stimulates the oyster to close and open more frequently, except shortly before the 
specimen finally dies. In order to show the typical changes in shell activity from 
beginning of an experiment until death of the oysters, several reproductions are given 
of portions of the kymograph records obtained in experiments Nos. 24 and 25. (Figs. 
34 to 38.) Figure 34 shows the reactions during the time when liquor was started. 
There is a distinct change of activity which consists in increased frequency of closures. 
