Rats fed low-protein rations increased food intake, weight gain and gain in lean body mass when forced to expend energy by low environmental temperature or exercise (swimming). Rats fed low-protein rations with a higher proportion of fat in their weight gain had a greater food intake and gain in lean body mass. Therefore, gain in lean body mass was improved not only by stimulating energy loss by cold environment or exercise but by an innate ability to deposit more fat in the weight gain, because of an increased food intake, and hence protein intake.

A pheromone produced by the female guppy, Poecilia reticulata, serves as a sexual attractant and stimulant to conspecific males. Addition of water from a container holding intact gravid "test" females caused an increase in male courtship directed towards ovariectomized "stimulus" females. There was no increase in courtship of males exposed to water from ovariectomized "test" females, and the response was not restored by treating the ovariectomized "test" females with estrogen. Pheromone production is prevented by hypophysectomy but is restored in hypophysectomized females by treatment with salmon gonadotropin or estrogen. These results indicate that pheromone is produced in the ovary itself under the control of ovarian hormone. Trials in which ovarian extracts or estrogen were added as test solutions failed to confirm earlier suggestions that the pheromone is present in ovarian tissue or that it is in fact an estrogen.

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