Growth-Promoting Power for Planarian Worms of Eosinophilic and Basophilic Cell Groups in Anterior Pituitary.

It has been demonstrated by Smith and Smith 1 that the injection of pituitary substances into hypophysectomized tadpoles produces 2 different effects according to the region of the anterior pituitary used. If the darker central core composed of basophil cells and chromophobes is injected the tadpoles grow more slowly and undergo metamorphosis more rapidly, while if one injects the surrounding lighter tissue, composed of eosinophil cells and chromophobes, the tadpoles grow unusually large. Although the separation of eosinophil and basophil cells in the pituitary is not complete, there is a sufficient predominance of the one in the outer portion and of the other in the central core to indicate that the growth stimulating principle arises from the eosinophil cells while that reacting with the endocrine system arises from the basophil cells.

Evans and Simpson 2 have also presented experimental evidence that 2 hormones are secreted by the anterior pituitary, one being a growth-promoting principle while the other reacts with the endocrine system. They consider their experiments to be concordant with the view that the one hormone is produced by eosinophil cells while the other is produced by basophil cells.

It seemed worth while to apply another test to determine whether the portion of the pituitary containing the greater number of eosinophil cells possesses a growth-promoting power exceeding that of the portion which contains the greater number of basophil cells. We used groups of planarian worms (Planaria agilis) newly regenerated from tails cut from our stock. Each group consisted of 30 worms, 6, 7, and 8 mm. long, and had a total length of 225 mm. The worms were fed twice a week over a period of 4 weeks when the total length of each group was again ascertained.