STUDIES ON THE PITUITARY.—VI. LOCALISATION AND PHYLETIC DISTRIBUTION OF ACTIVE MATERIALS

¹ Department of Physiology, University of Edinburgh, and the Department of Comparative Anatomy, University of Oxford

1. The oxytocic and avine depressor responses are given by extracts of the pituitary of mammals, birds, reptiles, amphibians, bony and cartilaginous fishes ; but the activity of extracts of the elasmobranch pituitary is in both respects so small compared with that of extracts of the teleost that no special significance can be attached to the failure of attempts to obtain a rise in blood-pressure from extracts of the skate's gland.

2. Comparison of the pressor and oxytocic activity of the same extracts of three separate samples of fresh bovine glands with Dale's uterine technique and the method of pressor standardisation outlined in a previous contribution to this series yielded results consistent with Herring's conclusion that, as compared with extracts of the pars nervosa, extracts of the pars intermedia have a higher oxytocic than pressor activity.

3. It is incorrect to state that there is no nervous tissue in the elasmobranch pituitary, though the nervous element is small in amount.

4. In the present state of knowledge it is perhaps premature to conclude either that the pressor and oxytocic material originate in the cells of the pars intermedia or that they pass directly into the cerebrospinal fluid via the pars nervosa.