unsupplomaiit,etl medium but the germinal elements only survived if
horse serum or chicken plasmrb wau added. Maturation of oocytes
would only continue if the gonads were cultured in the presence of
cxplnnted nourtd complex (GNV). This continued maturation of the
oocytes did riot occur when the gonad was associated with tissues other
than GNV. The implication from this work is that proper growth and
maturation of the gonads requires some substances present in the
neural complex.
There is then some very conflicting evidence concerning the possible
role of the neurrd complex in the control of reproduction in ascidiantj
and until far more critical work has been carried out we cannot resolve
this particular problem. One cannot escape from the fact that a!] of the
histological evidence pointe to the neural gland as being exocrine in
function and if any hormonal substances are present in the neural
complex they are more likely to exist in the neurosecretory cells of the
ganglion than in the neural gland.
3. Other function,? of ih,e nrurd gland
I t renitbins to eonHider what other possible functions may be served
by the nerirtil gland. These were reviewed by Butcher (1930) and
Ctirlisle (195 I ) both of' whom coiic:ludc~d th&t a pituitary-like function
wiiu the most, probablo. A few of the older suggestions merit some
comment.
(a) Mum9 yecrction (Roulq, 1884). There is no evidence that mucus
is secret>ed hy t h c glttnd (Bytcher, 1930) ttncl there would be no need for
it. Mucus or mucus-like uubstaneeu are secreted by the endoutyle and
provide all that is required in the food-collecting mechanism.
(b) Excretory organ (E. Van, Bentxien, quoted by Julin, 1881); Organ
of ptiagocytic ezrretion (PBrbs, 1943). Van Beneden clearly had some
sort of kidney in mind when he suggested an excretory function but
neither Roule ( I 884), Kowalevsky (1889) nor Butcher (1930) could
demonstrate any such funotion and recent hi~tological evidence (see
above) makes it clear that such a function would be impossible. Pdrh
( 1943), nevertheless, considered that it might be eliminating waste
prodiicts through a process of phagocytic excretion and that this would
explain the periodic sloughing of the glandular epithelium. However, if
such a funrtion wtts rieceusary it would be surprising to find that
cvolntlionary mechanisms should hrwe resulted in the discharge of these
~natei~ials iiit,o the beginning of the food cord when it might have been
dischnrgcd the other Ride of the mimtle wall arid into the atrial cavity.
I3utJcihrr (1!)30) poitit's out that, in iisridiaiis of the genus Phnllusia the
horse serum or chicken plasmrb wau added. Maturation of oocytes
would only continue if the gonads were cultured in the presence of
cxplnnted nourtd complex (GNV). This continued maturation of the
oocytes did riot occur when the gonad was associated with tissues other
than GNV. The implication from this work is that proper growth and
maturation of the gonads requires some substances present in the
neural complex.
There is then some very conflicting evidence concerning the possible
role of the neurrd complex in the control of reproduction in ascidiantj
and until far more critical work has been carried out we cannot resolve
this particular problem. One cannot escape from the fact that a!] of the
histological evidence pointe to the neural gland as being exocrine in
function and if any hormonal substances are present in the neural
complex they are more likely to exist in the neurosecretory cells of the
ganglion than in the neural gland.
3. Other function,? of ih,e nrurd gland
I t renitbins to eonHider what other possible functions may be served
by the nerirtil gland. These were reviewed by Butcher (1930) and
Ctirlisle (195 I ) both of' whom coiic:ludc~d th&t a pituitary-like function
wiiu the most, probablo. A few of the older suggestions merit some
comment.
(a) Mum9 yecrction (Roulq, 1884). There is no evidence that mucus
is secret>ed hy t h c glttnd (Bytcher, 1930) ttncl there would be no need for
it. Mucus or mucus-like uubstaneeu are secreted by the endoutyle and
provide all that is required in the food-collecting mechanism.
(b) Excretory organ (E. Van, Bentxien, quoted by Julin, 1881); Organ
of ptiagocytic ezrretion (PBrbs, 1943). Van Beneden clearly had some
sort of kidney in mind when he suggested an excretory function but
neither Roule ( I 884), Kowalevsky (1889) nor Butcher (1930) could
demonstrate any such funotion and recent hi~tological evidence (see
above) makes it clear that such a function would be impossible. Pdrh
( 1943), nevertheless, considered that it might be eliminating waste
prodiicts through a process of phagocytic excretion and that this would
explain the periodic sloughing of the glandular epithelium. However, if
such a funrtion wtts rieceusary it would be surprising to find that
cvolntlionary mechanisms should hrwe resulted in the discharge of these
~natei~ials iiit,o the beginning of the food cord when it might have been
dischnrgcd the other Ride of the mimtle wall arid into the atrial cavity.
I3utJcihrr (1!)30) poitit's out that, in iisridiaiis of the genus Phnllusia the