1. Concentrations of prolactin, growth hormone, testosterone, progesterone, thyroxine and triiodothyronine were measured in the blood plasma of female turkeys during successive periods of egg laying, a decline in lay, a moult induced by a short photoperiod (6 light: 18 dark) and a resumption of egg laying induced by a long photoperiod (16L:8D). 2. Concentrations of prolactin, growth hormone, testosterone and progesterone were higher in laying birds than in birds which were moulting or not laying. 3. The concentration of testosterone, but not of the other hormones studied, increased significantly during the period of profuse moult. 4. Concentrations of the thyroid hormones did not change with the varying physiological condition of the birds. However, the concentration of thyroxine was depressed by the long photoperiod.
Application of cold (4°C) together with wetness, acute anoxia, restraint or injection of saline (0.2 ml), epinephrine (0.2 mg), histamine (0.2 mg), or formaldehyde (0.2 ml, 40%) was followed by an acidophilia in white leghorn cockerels within 4–8 hours; acidophilia which followed injection of cortisone, hydrocortisone, desoxycorticosterone and aldosterone is consistent with the supposition that the above stressors activate the adrenocortical tissue of the chicken. Hypophysectomy markedly inhibited but did not wholly prevent the acidophilia which followed restraint therefore a nonpituitary factor is probably involved in stressor-induced acidophilia. This latter factor could be epinephrine but is probably not histamine since prior injection of antihistaminic agents did not inhibit restraint-induced acidophilia.
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