360
J. H. 8. BLAXTER AND F. 0. T. HOUIDAY
X, 8). The glandular lining of the oviduct produces a secretion which
bathes the ovulated eggs. Following ovulation the granulosa cells are
cast off the follicles and pass to the exterior.
(d) Recovery. As in the male there is a contraction and thickening of the
connective tissue. A further crop of oooytes is formed to augment the
resting oocytes of the previous year.
( e ) Degeneration of eggs. Pre- and post-ovulatory degeneration of eggs
occurs in all clupeids that have been studied, but nothing resembling a
glandular " corpus luteum " is formed as a result of this degeneration.
There is so far no evidence of any endocrine activity in the herring
HJORT'S STAG€
Fro. 23. Change in diameter of oocyteH (rnm) with rnaturatictn wtagtt. (ItAprdul.ml
with permiaeion from Bowurn und Hollidsy, lirf3l.)
ovary. Weismari et al. (1936) assayed extracts on immature mice but
obtained no response.
4. Fecundity
This has been studied in considerable detail recently a8 R character
with which to distinguish one stock of herring from anothw, r q . naxhr
(1959). Marty (1956) gave an excellent Hummary of fcciirrrlity in rdatiorl
to race, age and length (see Fig. 24). NagaHaki ( 1 958) Htlldi4:d fr:ciindity
in Clupea pallasii and MacOregor (1950) corrcltlted fecundity with
length, ago and weight in h'ardinmps caerulea.
Thorct is probably a niaximilm fecundity for a given fish that is
germtically dotrrmincd, and attaiiied under perfectly suitable environmetital conditions. It is likely that available food supply, age,
J. H. 8. BLAXTER AND F. 0. T. HOUIDAY
X, 8). The glandular lining of the oviduct produces a secretion which
bathes the ovulated eggs. Following ovulation the granulosa cells are
cast off the follicles and pass to the exterior.
(d) Recovery. As in the male there is a contraction and thickening of the
connective tissue. A further crop of oooytes is formed to augment the
resting oocytes of the previous year.
( e ) Degeneration of eggs. Pre- and post-ovulatory degeneration of eggs
occurs in all clupeids that have been studied, but nothing resembling a
glandular " corpus luteum " is formed as a result of this degeneration.
There is so far no evidence of any endocrine activity in the herring
HJORT'S STAG€
Fro. 23. Change in diameter of oocyteH (rnm) with rnaturatictn wtagtt. (ItAprdul.ml
with permiaeion from Bowurn und Hollidsy, lirf3l.)
ovary. Weismari et al. (1936) assayed extracts on immature mice but
obtained no response.
4. Fecundity
This has been studied in considerable detail recently a8 R character
with which to distinguish one stock of herring from anothw, r q . naxhr
(1959). Marty (1956) gave an excellent Hummary of fcciirrrlity in rdatiorl
to race, age and length (see Fig. 24). NagaHaki ( 1 958) Htlldi4:d fr:ciindity
in Clupea pallasii and MacOregor (1950) corrcltlted fecundity with
length, ago and weight in h'ardinmps caerulea.
Thorct is probably a niaximilm fecundity for a given fish that is
germtically dotrrmincd, and attaiiied under perfectly suitable environmetital conditions. It is likely that available food supply, age,