. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. THYROID TREATMENT OF DOGFISH 115 ally through most of the three-week period of observation ; in the second experiment (Fig. 3) this variation was, in general, less and showed no such constant trend. Fortunately, the general variation of the controls was paralleled by the hormone- injected embryos, and in addition, a relative difference from the controls was usually maintained, if it occurred at all. Accordingly, when the results are ex- pressed as per cent of the control oxygen consumption some conclusions appear to be offer
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. THYROID TREATMENT OF DOGFISH 115 ally through most of the three-week period of observation ; in the second experiment (Fig. 3) this variation was, in general, less and showed no such constant trend. Fortunately, the general variation of the controls was paralleled by the hormone- injected embryos, and in addition, a relative difference from the controls was usually maintained, if it occurred at all. Accordingly, when the results are ex- pressed as per cent of the control oxygen consumption some conclusions appear to be offered (Table III, Fig. 4). The most potent stimulator of oxygen consumption in these tests was triiodo- thyroacetic acid (Fig. 4A). Despite all the variations to which such experiments seem to be prone, in all four experiments in which Triac was injected in 10- microgram quantities, it clearly induced an increase in oxygen consumption to maxima 17% to 33% above the control. These maxima were achieved 8 to 10 days after beginning the injections and thereafter oxygen consumption progressively 45 o u O 40 Q. CO O 35 o z UJ o O 30 o. 34567 NUMBER OF INJECTIONS 8 FIGURE 3. The effects of repeated injections of thyroid compounds on metabolic rate of dogfish embryos—injection group 2. Solid line, control; dashed line, triiodothyroacetic acid (10/ttg.) ; dotted line, 1-thyroxine (10/ug.). decreased. The larger dose of Triac (100 micrograms) was less effective than the smaller one (Table III). Thyroxine, in 10-microgram doses, was not as clearly a stimulator of oxygen consumption in the Sqitahts pups as was Triac. It consistently raised oxygen consumption in two of four experiments (Table III, Fig. 4B) above that of controls, but failed to do so in one, and in another did not produce a significant stimulation until the very end. However, in all thyroxine experiments oxygen consumption was rising at the end of the period of treatment, in comparison with the controls. In one test with 100-
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
