20
VICTOR L. LOOSANOFF AND HARRY C. DAVIS
were conditioned (Fig. 10). These dishes are partly immersed in a
large tray or sink, which is filled with hot water, thus quickly raising the
temperature in the dishes to the desired level (Fig. 11).
I n some instances thermostimulation alone is sufficient to induce
spawning. In other cases, however, mollusks need additional stimulation, which consists of adding to the water small quantities of sperm
or egg suspension made from gonadal material of ripe individuals of the
same species. Many forms quickly respond to combined thermal and
chemical stimuli ; others, such as the common mussel, Mytilm edulis,
do not usually respond to this method but can, nevertheless, be
induced to sFawn by other means, which will be discussed later.
I n a special series of experiments we tried to cause artificial discharge
of reproductive elements by injecting weak solutions of Mn,OH and
other chemicals into the bodies of bivalves that could not be spawned
by other means. The results were usually not gratifying, except in the
case of M. edulis, when injection was made in its adductor muscle.
At the time of our experiments to induce spawning in ripe bivalves
we were already aware of the success of Japanese workers in inducing
spawning in mussels by giving them a mild electric shock. We repeated
these experiments but, unfortunately, with indifferent results.
In still other species, for example, Modiolus demissus, all our
methods, including those that were successful in the case of Mytilwr
edulis, proved to be ineffective in inducing spawning. Therefore, unlese
ribbed mussels spawn naturally, thus providing normally fertilized
eggs, no other means, except perhaps stripping, are left for obtaining
their spawn.
Fertilizable eggs of many q)ecics, including thom of C. uirginica
(BrookB, 1880), can be ohtainvd Ijy fitripping matiirr: fr:mitbn hiit,
since many of these forms spawn HO readily in rcqJonwc: to chemical
and thermal stimulations, it is seldom necessary to resort to thie mectne.
However, when working with other species, especially those that
cannot be spawned by conventional methods, stripping may be the
only way to obtain ripe eggs. It i H a Himplc procem arid i~ carried an
as follows: After removing the outer memhranc? that cr)vorH thH gonda,
the mollusk is gently r i n d in nea water. Thiw ar:t,ion Hc!lJwat,.en front
the gonad large number8 of egg8 without rw:rioon irrjiiry b them.
Using a series of sieves of proper size meRh tho ~ g g ~
arc later frmd of
bIood cells, pieces of tissue, etc., and then placed in 8ea wator to which
sperm is added. The fertilized eggs can then be placed in culture
vessels.
This approach is possible only for eggs of those forms in which the
germinal vesicle dissolves after stripping. In many species, however,
VICTOR L. LOOSANOFF AND HARRY C. DAVIS
were conditioned (Fig. 10). These dishes are partly immersed in a
large tray or sink, which is filled with hot water, thus quickly raising the
temperature in the dishes to the desired level (Fig. 11).
I n some instances thermostimulation alone is sufficient to induce
spawning. In other cases, however, mollusks need additional stimulation, which consists of adding to the water small quantities of sperm
or egg suspension made from gonadal material of ripe individuals of the
same species. Many forms quickly respond to combined thermal and
chemical stimuli ; others, such as the common mussel, Mytilm edulis,
do not usually respond to this method but can, nevertheless, be
induced to sFawn by other means, which will be discussed later.
I n a special series of experiments we tried to cause artificial discharge
of reproductive elements by injecting weak solutions of Mn,OH and
other chemicals into the bodies of bivalves that could not be spawned
by other means. The results were usually not gratifying, except in the
case of M. edulis, when injection was made in its adductor muscle.
At the time of our experiments to induce spawning in ripe bivalves
we were already aware of the success of Japanese workers in inducing
spawning in mussels by giving them a mild electric shock. We repeated
these experiments but, unfortunately, with indifferent results.
In still other species, for example, Modiolus demissus, all our
methods, including those that were successful in the case of Mytilwr
edulis, proved to be ineffective in inducing spawning. Therefore, unlese
ribbed mussels spawn naturally, thus providing normally fertilized
eggs, no other means, except perhaps stripping, are left for obtaining
their spawn.
Fertilizable eggs of many q)ecics, including thom of C. uirginica
(BrookB, 1880), can be ohtainvd Ijy fitripping matiirr: fr:mitbn hiit,
since many of these forms spawn HO readily in rcqJonwc: to chemical
and thermal stimulations, it is seldom necessary to resort to thie mectne.
However, when working with other species, especially those that
cannot be spawned by conventional methods, stripping may be the
only way to obtain ripe eggs. It i H a Himplc procem arid i~ carried an
as follows: After removing the outer memhranc? that cr)vorH thH gonda,
the mollusk is gently r i n d in nea water. Thiw ar:t,ion Hc!lJwat,.en front
the gonad large number8 of egg8 without rw:rioon irrjiiry b them.
Using a series of sieves of proper size meRh tho ~ g g ~
arc later frmd of
bIood cells, pieces of tissue, etc., and then placed in 8ea wator to which
sperm is added. The fertilized eggs can then be placed in culture
vessels.
This approach is possible only for eggs of those forms in which the
germinal vesicle dissolves after stripping. In many species, however,