172 
BULLETIN OF THE BUREAU OF FISHERIES 
at 30- to 60-minute intervals, and are continued for from 2 to 4 hours, the average 
rate of flow for this period being considered as the normal rate of pumping. The 
flow of sea water is then cut off, if it has not already been stopped, and a predeter- 
mined amount of sea water is siphoned off and immediately replaced by the same 
amount of oil extract, prepared in the manner described below. The solution is 
allowed to remain in the tray from 1 to 24 hours, during which time measurements 
of the rate of flow are made, first at 15-minute intervals, later at 30- and 60-minute 
intervals. Measurements on controls run for the same period of time. The total 
elapsed time for these experiments, from preparation of the oyster to removal from 
the tray, averages 26 hours. 
Treatment with soluble fraction is followed by fresh sea water, measurements 
being made hourly to indicate the rate and extent of recovery. The plugs, tubing, 
and glass rod are then removed; and the oyster, suitably marked for future identi- 
fication, is returned to the large laboratory aquarium. 
cell connected to the chamber; E, overflow; P, drop counter; S, key switch connecting the signal magnet (Hi); Si, key switch 
connecting the circuit in the drop counter and 45 volt “ B ” battery (B 2 ); K, kymograph; T, electriaclock; B, storage battery; 
Bj, 2-volt dry cells for operation of the signal magnet (Mi); and M, signal magnet connected with a drop counter P. 
DROP-COUNTING APPARATUS 
The apparatus is illustrated in figure 5. There are three main parts: 
1. Supply ( w ), experimental chamber (Ch) and recording apparatus ( k ). A 
three-way stopcock (A) supplies either laboratory sea water or a test solution. A 
constant level device maintains equal pressure for both liquids, delivering 200 cc per 
minute to the experimental chamber. Temperature fluctuations are kept within 
1° C. of the laboratory sea water. 
2. Experimental chamber (Ch) consists of a celluloid box of 1,500 cc capacity 
with a small cell ( D ) of the same material attached to its wall and connected through 
the side by a short piece of glass tubing. An overflow tube (E) in the center of the 
small cell drains through the bottom. The height of this tube must be so adjusted 
that when the two chambers are connected the water in both of them remains in 
