THE PHYSIOLO(XY OF ASCIDIANS
116
and Dodd and Ihdd show evidence thikt the effects cannot be caused by
potassium, ttcetylcholine, histamine OT B-hydroxytrypt,amine.
Dodd arid Uodd did iiot find any vasopressor activity in neural
complcx extracts assayed on rats, but did find that these extracts and
those of control tissues, cltused an initial fall in blood pressure after
injection into ruts. This phenomc?non was also noted by Bacq and Florkin (1935). Such a depressor activity could be due to histamine but
Dodd and Dodd note that the effect is such that. if it were due to histamine alone this substance would have to represent 2.6% by weight of
the neural gland tissue which is most unlikely.
Finally Dodd and Dodd found no evidence for the presence of an
anti-diuretic hormone or a melariocyte stimulating hormone in neyral
-
A
-
0
I
1
1
I
I
Pro. 42. Tho tlifhrcmcct i t 1 latency betwetw oxtractx of' Cionci neural cornplox and Pitooin
(A) Pcriotl of injctctioti of f'ttociri (0.8 ImU): (H) Period of
(%drawn
on the rat utotws.
injection of ntwml complex extract (2.6 ing).
from Ilodti and I)odtl, 1066.)
Time ~ctrlt? 10 noconds.
complex extracts. The absence of MSH (Fig. 33) is in conflict with the
findings of several other authors (13acq nnd Plorkin, 1935 ; Abramowitz,
1937 ; Carlisle, 19BOa ; Carlisle and Olsson, 1966). Dodd and Dodd used
a specially eelccted strain of Xenoptis laevis for bio-assay of MSH, in
which the reltct>ions of the chromatophores are well understood, and
they point out that the reectionn of chromatophorefl in tent anirnltlH
used by these other workers are poorly known and therefore interpretation of bio-assay work in which they are uRed is very difficult.
Table XIV summarizes the work of Dodd and Dodd in respect of
posterior pituitary hormones. It is clear from thiH table and the precision of their experimental tmhniques that there is little evidence for the
existence in the ascidian neural complex of any of the normal posterior
pituitary hormones. There is, however, clear evidence in their work and
in the work of other authors cited here, for the presence of a smooth
116
and Dodd and Ihdd show evidence thikt the effects cannot be caused by
potassium, ttcetylcholine, histamine OT B-hydroxytrypt,amine.
Dodd arid Uodd did iiot find any vasopressor activity in neural
complcx extracts assayed on rats, but did find that these extracts and
those of control tissues, cltused an initial fall in blood pressure after
injection into ruts. This phenomc?non was also noted by Bacq and Florkin (1935). Such a depressor activity could be due to histamine but
Dodd and Dodd note that the effect is such that. if it were due to histamine alone this substance would have to represent 2.6% by weight of
the neural gland tissue which is most unlikely.
Finally Dodd and Dodd found no evidence for the presence of an
anti-diuretic hormone or a melariocyte stimulating hormone in neyral
-
A
-
0
I
1
1
I
I
Pro. 42. Tho tlifhrcmcct i t 1 latency betwetw oxtractx of' Cionci neural cornplox and Pitooin
(A) Pcriotl of injctctioti of f'ttociri (0.8 ImU): (H) Period of
(%drawn
on the rat utotws.
injection of ntwml complex extract (2.6 ing).
from Ilodti and I)odtl, 1066.)
Time ~ctrlt? 10 noconds.
complex extracts. The absence of MSH (Fig. 33) is in conflict with the
findings of several other authors (13acq nnd Plorkin, 1935 ; Abramowitz,
1937 ; Carlisle, 19BOa ; Carlisle and Olsson, 1966). Dodd and Dodd used
a specially eelccted strain of Xenoptis laevis for bio-assay of MSH, in
which the reltct>ions of the chromatophores are well understood, and
they point out that the reectionn of chromatophorefl in tent anirnltlH
used by these other workers are poorly known and therefore interpretation of bio-assay work in which they are uRed is very difficult.
Table XIV summarizes the work of Dodd and Dodd in respect of
posterior pituitary hormones. It is clear from thiH table and the precision of their experimental tmhniques that there is little evidence for the
existence in the ascidian neural complex of any of the normal posterior
pituitary hormones. There is, however, clear evidence in their work and
in the work of other authors cited here, for the presence of a smooth