Abstract
In earlier work the writer has shown that destruction of the cerebral hemispheres and the optic thalamus of birds reduces the animal permanently to a poikilothermous condition. In birds this is not an operation that leads to immediate death for they may be kept alive for one to three months by keeping them constantly at an atmospheric temperature of 30° to 35° C. The routine procedure was to remove the cerebral hemispheres in toto by the scalpel and then destroy the optic thalamus with an electro-cautery.
It has been pointed out elsewhere that to produce the poikilothermous condition there must be extensive destruction of the thalamus and that localized injuries did not appreciably change the body temperature regulation. This destruction of the structures around the third ventricle, it is obvious, might also involve the hypophysis. Inasmuch as a subnormal temperature is among the cycle of disturbances following injuries or removal of the hypophysis (Cushing and others) the temperature disturbance might be attributed to hypophyseal injury, rather than to the lesion in the brain. The experiments have been repeated therefore taking particular care not to traumatize the hypophysis.
A series of pigeons were reduced to the poikilothermous condition by cauterization of the thalamus. After death absence of any gross visible changes in the hypophysis was confirmed. The organ in each of these animals had a perfectly normal appearance although there may have been circulatory alterations or cytological changes invisible to the naked eye.
However this may be the injection intra-peritoneally of from .2 to 1.0 C.C. of pituitary extract (posterior lobe-Lilly) causes a sharp rise in body temperature of the poikilothermous birds.
Injection of the extract into normal birds causes no temperature reaction greater than the range of the diurnal variations.
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