14
VICTOR L. LOOSANOFF A N D HARRY C. DAVIS
special Imcautions art' noct?smry to prevent its Ht,rntilict~tiol\. 'l'o
achieve this in the enclosure where our racks of trays aro kcpt a large
fan forcing air through has been found sufficient.
Still another temperature apparatus is used at our laboratory for
simultaneous studies of growth of juvenile mollusks in running water
of different but constant temperatures (Fig. 9). The entire apparatus
consists of seven independent units, each insulated so as not to be
affected by outside temperatures. As many as five trays may be placed
in each chamber. By mixing, in winter, different proportions of warm
and cold sea water, temperatures ranging from about 5" to 35°C can
be maintained quite accurately.
The amount of water entering each tray can be adjusted to a
desired rate and, when necessary, the trays in all seven chambers may
receive the same quantity of water and plankton food per hour. Ae a
rule, sea water and food, before entering trays containing juvenile
mollusks, are passed through the special unit where they are sterilized
by ultraviolet rays.
I n addition to various apparatus and devices discussed in thia
section there are several others that have been used in special studies.
A description of these will bc given elsewhere.
111. CONDITIONING MOLLUSKS FOR OUT-OF-SEASON SPAWNING
Before the present method of providing laboratories with warm
water in winter was developed, experiments on most of the bivalves
and, especially, their larvae were confined, in New England waters
and similar areas, almost exclusively to the short periods of natural
propagation, usually lanting for'only the '24 or 3 Hummer month
However, since i t was found that in many hivalvc:n, by uning p r q w
conditioning methods, norms1 de-elopmen t of gonuln can b: n t h u b t w l
and spawning induced during late fall, winter and Rpring, the e x p r i -
mental period has been greatly expanded (Looanoff, 1948).
Conditioning of bivalves to develop mature gonads during the cold
part of the year is relatively simple. It consists of placing mollusks,
brought from their natural environment where water temperature may
be near freezing, into somewhat warmer water and then gradually
increasing the temperature several degrees each day until tho desired
level is reached (Loosanoff and DaviR, 1060). Sometimc~, especially
towards tho spring, instoad of a gradual conditioning the mollusks
can tw p l ~ t d dircctly in wrktcr of about 20°C. As a rule, the gametes
obtainotl from theee mollusks were no less viable than from those
conditioned gradually. We have often employed this more rapid
VICTOR L. LOOSANOFF A N D HARRY C. DAVIS
special Imcautions art' noct?smry to prevent its Ht,rntilict~tiol\. 'l'o
achieve this in the enclosure where our racks of trays aro kcpt a large
fan forcing air through has been found sufficient.
Still another temperature apparatus is used at our laboratory for
simultaneous studies of growth of juvenile mollusks in running water
of different but constant temperatures (Fig. 9). The entire apparatus
consists of seven independent units, each insulated so as not to be
affected by outside temperatures. As many as five trays may be placed
in each chamber. By mixing, in winter, different proportions of warm
and cold sea water, temperatures ranging from about 5" to 35°C can
be maintained quite accurately.
The amount of water entering each tray can be adjusted to a
desired rate and, when necessary, the trays in all seven chambers may
receive the same quantity of water and plankton food per hour. Ae a
rule, sea water and food, before entering trays containing juvenile
mollusks, are passed through the special unit where they are sterilized
by ultraviolet rays.
I n addition to various apparatus and devices discussed in thia
section there are several others that have been used in special studies.
A description of these will bc given elsewhere.
111. CONDITIONING MOLLUSKS FOR OUT-OF-SEASON SPAWNING
Before the present method of providing laboratories with warm
water in winter was developed, experiments on most of the bivalves
and, especially, their larvae were confined, in New England waters
and similar areas, almost exclusively to the short periods of natural
propagation, usually lanting for'only the '24 or 3 Hummer month
However, since i t was found that in many hivalvc:n, by uning p r q w
conditioning methods, norms1 de-elopmen t of gonuln can b: n t h u b t w l
and spawning induced during late fall, winter and Rpring, the e x p r i -
mental period has been greatly expanded (Looanoff, 1948).
Conditioning of bivalves to develop mature gonads during the cold
part of the year is relatively simple. It consists of placing mollusks,
brought from their natural environment where water temperature may
be near freezing, into somewhat warmer water and then gradually
increasing the temperature several degrees each day until tho desired
level is reached (Loosanoff and DaviR, 1060). Sometimc~, especially
towards tho spring, instoad of a gradual conditioning the mollusks
can tw p l ~ t d dircctly in wrktcr of about 20°C. As a rule, the gametes
obtainotl from theee mollusks were no less viable than from those
conditioned gradually. We have often employed this more rapid