92
VIFTOR L. LOOSANOFF AND HARRY c. DAVIS
apparently normal way, forming true feces and pseudo-feces. Mussels
that were placed together in large trays with running sea Water eventually attached to each other by their byssus.
Since the second series of experiments has also showed that discharge of spawn in mussels of both sexes can be induced by stretching
the posterior adductor muscle, it became more certain that the nerve
locus causing the discharge is located there. Accordingly, it w&8
decided to stimulate this region, by touching or pricking it with a
sharp needle, and note whether this type of stimulation would a h
induce spawning reaction.
I n the middle of March two groups of mussels, each composed of
ten individuals, were placed in running water at a temperature of 19°C.
The first group, the control, contained individuals that were not stimulated. I n the second group each individual waa gently stimulated by
pricking the muscle. The first male in the stimulated group spawned
in about 2 hr. An hour later the first female spawned and continued
to discharge eggs for almost 75 min. The eggs were discharged in
orange-colored rods, 3 to 4 mm long. These rods were often expelled
with such force that they travelled 4 to 5 in away from the spawning
female.
Seven hours after the stimulation another male spawned, and after
9 hr two more females began to discharge spawn. Within 12 hr every
individual in the stimulated group had spawned, while none in the
control group had done so. Thus, it was demonstrated that needling
the adductor muscle is an effective method of inducing spawning
in M. edulis.
All mussels that had spawned were later placed in running @a
water to see whether they would survive the stimulation treatment.
All of them lived for over a month and were then discarded.
Although the previously-described experiment had demonstrated
that pricking of the adductor muscle stimulated spawning of mussels,
the fact that all ten animals were kept in the same dish left some
doubt aa to the exact conditions that caused spawning during the
latter Part of the experiment. This doubt existed because toward the
end both sperm and eggs were present in the water and, therefore,
have helped to stimulate the mussels that had not yet spawned.
matter another experiment was designed in which we
kept each mussel in a separate dish. Again, ten mussels were used
in the
g o u p and ten in the group that was stimulated. The
'pawned 30 min after stimulation and the first female began
to discharge eggs hr after its muscle had been gently touched several
t h e s with the point Of a needle. The second female spawned only
VIFTOR L. LOOSANOFF AND HARRY c. DAVIS
apparently normal way, forming true feces and pseudo-feces. Mussels
that were placed together in large trays with running sea Water eventually attached to each other by their byssus.
Since the second series of experiments has also showed that discharge of spawn in mussels of both sexes can be induced by stretching
the posterior adductor muscle, it became more certain that the nerve
locus causing the discharge is located there. Accordingly, it w&8
decided to stimulate this region, by touching or pricking it with a
sharp needle, and note whether this type of stimulation would a h
induce spawning reaction.
I n the middle of March two groups of mussels, each composed of
ten individuals, were placed in running water at a temperature of 19°C.
The first group, the control, contained individuals that were not stimulated. I n the second group each individual waa gently stimulated by
pricking the muscle. The first male in the stimulated group spawned
in about 2 hr. An hour later the first female spawned and continued
to discharge eggs for almost 75 min. The eggs were discharged in
orange-colored rods, 3 to 4 mm long. These rods were often expelled
with such force that they travelled 4 to 5 in away from the spawning
female.
Seven hours after the stimulation another male spawned, and after
9 hr two more females began to discharge spawn. Within 12 hr every
individual in the stimulated group had spawned, while none in the
control group had done so. Thus, it was demonstrated that needling
the adductor muscle is an effective method of inducing spawning
in M. edulis.
All mussels that had spawned were later placed in running @a
water to see whether they would survive the stimulation treatment.
All of them lived for over a month and were then discarded.
Although the previously-described experiment had demonstrated
that pricking of the adductor muscle stimulated spawning of mussels,
the fact that all ten animals were kept in the same dish left some
doubt aa to the exact conditions that caused spawning during the
latter Part of the experiment. This doubt existed because toward the
end both sperm and eggs were present in the water and, therefore,
have helped to stimulate the mussels that had not yet spawned.
matter another experiment was designed in which we
kept each mussel in a separate dish. Again, ten mussels were used
in the
g o u p and ten in the group that was stimulated. The
'pawned 30 min after stimulation and the first female began
to discharge eggs hr after its muscle had been gently touched several
t h e s with the point Of a needle. The second female spawned only