7 
to an embryonic stage in which the antennae were provided 
with long transparent feather-like outgrowths. The various 
stages through which the embryo passed need not be here 
fully described. It is sufficient to note that after several 
weeks the embryonic development was completed and the 
young crawfish escaped from the egg in a perfectly normal 
condition. Thousands of such young could be readily procured. 
At first the young crawfish swam rapidly to the surface by 
the feather-like antennae, the other appendages being folded 
close to the body and not used (the naupliosoma stage). In 
a few hours after gaining the surface they passed into the 
phyllosoma stage, and were able to move in a horizontal 
direction, always congregating at the most lighted part of the 
water as already noted in previous experiments. 
It was thus shown that the crawfish can be hatched out 
from the egg from its earliest stages and the larvae procured 
in unlimited numbers. It was, however, found that though 
the young crawfish could be artificially tided over the egg 
stage, the free surface-swimming, to which they could be 
reared, was even more liable to attacks of enemies. Thus 
when a few hundred newly-hatched larvae were placed in a 
large tank containing fish they were almost at once attacked 
by the surface-feeding harders (mullet). | The other fish in 
the tank did not readily attack them ; thus a few were taken 
by maasbankers, though none were taken by dasjes which were 
present. 
Obviously therefore the next series of experiments had 
to be directed to the solution of this more serious difficulty, 
viz., the possibility of protecting the surface-swimming stages 
of the naupliosoma and the phyllosoma. Attempts were 
first made to ascertain how long these surface stages lasted, 
and when the young crawfish began to descend to the com- 
parative safety of the ground-feeding conditions. The nau- 
pliosoma stage had been found by former experiments to 
last, fortunately, only a very short time (a few hours), but 
what became of the phyllosoma stage had not yet been ascer- 
tained. A series of experiments under various conditions 
was then undertaken, but it was found that it was difficult 
to keep this stage alive. After swimming about for a few 
days the young crawfish gradually disappeared, and the 
dead remains of many were seen on the bottom of the tank, 
the cause of death being apparently the presence of debris 
of seaweed, etc., in the water, clogging up the swimming 
appendages. Rearing in filtered sea water was then tried, 
but without success as the necessary food for the young was 
apparently removed in this process. Feeding on a variety 
of material was then attempted but without success. Finally 
it was found that the most successful method was to partially 
filter the water. 
[C.P. 3—1918] 
