THE ARTIFICYIAL PROPAGATION OP MABINIP FISH
69
sight and food conditions were similar to those desoribed for the
p v i o u s experiment.
The eight incubators were stocked with 1000 pond-spawned eggs
each, in the blastula stage of development (less than 24 h old).
Although tanks could be supplied with hatchery water overflowing to
waste, only one tank of a pair was irrigated during the period of egg
incubation. The other waa treated with one dose of penicillin and
Water both 1
800
A. x %.h
'Oo0
-TZ\ --.
" 8
L n .
' a ,
' L.
600 -
t
M
i 2001 H t
F t
f?
t
F
t
M
20
40
60
80
100
0
20
40
60
80 100
Days after start of experiment
Fro. 17. Survival curves of plaice stock in different temperature condition8 (BBB
Fig. 16), with ( .
.
.
)
and without ( x x x ) anti-biotic treatment. H = hatching complete;
F = feeding established; M = metamorphosis complete.
streptomycin at the concentrations already stated, and then kept
static until hatching began. All tanks were irrigated during the subsequent larval phases.
The temperature regime for each water bath is indicated in Fig. IS.
After 2 days acclimatization at 6"C, the temperatures of three water
baths were slowly increased, at a mean rate of 1°C per week, to give
8") 7", 8' and 9°C in water baths 1, 2 , 3 and 4 respectively, at the time
A.u.n.-g
a