Search

The preparation by McGee (6) of extracts of bull testes that stimulated growth of the comb of castrated cocks and the subsequent advances in the purification of these extracts by Gallagher and Koch (1, 2) are now well known. Similarly, through the publications of Moore and his associates (7, 8, 9), it has been demonstrated that these extracts prevent the onset of castration changes in the mammal, or repair them if administered subsequent to castration damage [Vatno (14), Heller (4)]. Several mammalian test methods have been utilized, all of which have dealt with the accessory organs of reproduction. Since it is necessary to know that these preparations are effective in preventing all changes known to follow castration before arriving at the conclusion that they contain the complete hormone, I have made a study of the spontaneous activity in the rat in relation to its hormone state to learn whether voluntary activity can be successfully used as a hormone indicator.