97 
Brae her. — Observations on Euglena deses. 
Mud (M.) is placed in the glass tank T in the position shown in 
diagram. Cement dams (cq and c 2 ) serve to keep the mud in position. 
Water is stored in two vessels (a x and A 2 ) which are connected by the 
siphon S r By means of a tap at the base of the siphon S 2 water is run 
drop by drop into the bottle B. By keeping this always overflowing, the 
pressure of water in the bottle remains approximately constant. By means 
of the tap water from the bottle is then run into the inverted bell-jar J. 
The indicator I enables the stop-cock to be kept at a definite angle, and 
T Tank. 
Fig. 3. 
by adjusting this the time taken to fill the bell-jar may be regulated. 
By trial it was possible to fill the bell-jar to the required level in twelve 
hours. In reaching the level of the siphon s 3 the water all passes over 
into the tank by means of the tube X, and high tide is effected. The 
outgoing tide is arranged thus : As the water rises in the tank T it also 
rises in the glass cylinder K, the two being connected by the siphon S 4 . 
This cylinder is too narrow to allow any appreciable fall of water to take 
place in the tank. On reaching the level of the siphon S 5 the water in 
the cylinder is gradually passed off by means of slow dripping from the tap 
at the end of the siphon, and accordingly the water is gradually emptied 
from the tank until it reaches the level of the upper end of siphon S 5 
within the cylinder, when air enters and the flow of water is stopped. By 
H 
