120
IVAN l;OOl)UODY
accept hi8 interprotation. In the first place Millar (1953a) and P&&s
(1943) insiet that the ciliary currents beat material out of the ciliated
funnel and not into the gland ; Georges (1971) considers that they draw
materid into the gland and Carlisle claimed to have found gametes in
the gland when sectioned after feeding on sperm and ova. Secondly if
cross fertilieibtion with other spawning ascidians of their own species ig
the goal then the response to gametes in the water should be immediate
and not have a time delay of 20 hours. Under normal circumstances
one would expect the response to involve release of the gonoduct
sphincter and contraction of the mantle, rather than increased gamete
production. Reference has already been made to the work of Pdr&s
(1954) on the ovarian rycle which suggests that the scheme prepared
by Carlisle cannot be correct.
If there is a gonadotrophin present in the neural gland or if the
gland in any way controls reproduction we would expect that surgical
retnovnl of the gland should disrupt the sexual cycle. Hisaw et al.
(1 966) examined this possibility in Chelyosoma productum. The whole
or a part of the neural complex was removed from animals after spawning was completed in summer and before growth of gonadial tissue had
commenced again. No regeneration of neural tissues occurred and the
animals, aftw extirpation of the complex, were returned to the sea to
continue their growth. Thc ascidians were re-examined at intervals
varying froin one month to a, year and there was no evidence at all that
extirpation of the neural complex had interfered with the gonadial
growth cycle neither did it modify the subsequent spawning Eeason.
However, in interpreting these experiments we must bear in mind that
P&s (1 943, 1047) and Lender and Bouchard-Madrelle (1 964) report
that the neural gland has considerable powers of regeneration. Furthermore these experiments are at variance with those of Bouchard-Madrelle
(1967) who reports that extirptttion of the neural complex causes a
decrease in the number of germinal centres in the ovary and in the
number of mature follicles. He also Ntates that removal of all or part of
the complex shaws that the neural gland controls the number of young
oocytes while the ganglion controls the numher of mature follicles and
the number of oocytes in perivitellogenesis. Experiments carried out
by SerigrI aiid George (1966) suggest that the neural gland may alno
have an inhibitory effect on the spawning prpcess.
Finally in this context reference should be made to the work of
Sengel and Kieny (1902, 1963a, 1963b) who cultured the gonads of
Molgulcl nianhattensis irt oitro. Immature and mature gonads were
cultured for seven days on various media of sea water and agar with
Qdded penicillin. SomcLtic tissues of the gonad8 survived well on the
IVAN l;OOl)UODY
accept hi8 interprotation. In the first place Millar (1953a) and P&&s
(1943) insiet that the ciliary currents beat material out of the ciliated
funnel and not into the gland ; Georges (1971) considers that they draw
materid into the gland and Carlisle claimed to have found gametes in
the gland when sectioned after feeding on sperm and ova. Secondly if
cross fertilieibtion with other spawning ascidians of their own species ig
the goal then the response to gametes in the water should be immediate
and not have a time delay of 20 hours. Under normal circumstances
one would expect the response to involve release of the gonoduct
sphincter and contraction of the mantle, rather than increased gamete
production. Reference has already been made to the work of Pdr&s
(1954) on the ovarian rycle which suggests that the scheme prepared
by Carlisle cannot be correct.
If there is a gonadotrophin present in the neural gland or if the
gland in any way controls reproduction we would expect that surgical
retnovnl of the gland should disrupt the sexual cycle. Hisaw et al.
(1 966) examined this possibility in Chelyosoma productum. The whole
or a part of the neural complex was removed from animals after spawning was completed in summer and before growth of gonadial tissue had
commenced again. No regeneration of neural tissues occurred and the
animals, aftw extirpation of the complex, were returned to the sea to
continue their growth. Thc ascidians were re-examined at intervals
varying froin one month to a, year and there was no evidence at all that
extirpation of the neural complex had interfered with the gonadial
growth cycle neither did it modify the subsequent spawning Eeason.
However, in interpreting these experiments we must bear in mind that
P&s (1 943, 1047) and Lender and Bouchard-Madrelle (1 964) report
that the neural gland has considerable powers of regeneration. Furthermore these experiments are at variance with those of Bouchard-Madrelle
(1967) who reports that extirptttion of the neural complex causes a
decrease in the number of germinal centres in the ovary and in the
number of mature follicles. He also Ntates that removal of all or part of
the complex shaws that the neural gland controls the number of young
oocytes while the ganglion controls the numher of mature follicles and
the number of oocytes in perivitellogenesis. Experiments carried out
by SerigrI aiid George (1966) suggest that the neural gland may alno
have an inhibitory effect on the spawning prpcess.
Finally in this context reference should be made to the work of
Sengel and Kieny (1902, 1963a, 1963b) who cultured the gonads of
Molgulcl nianhattensis irt oitro. Immature and mature gonads were
cultured for seven days on various media of sea water and agar with
Qdded penicillin. SomcLtic tissues of the gonad8 survived well on the