I n a recent review of neurosecretion the hypothesis has been advanced that the products of the neurosecretory process originate in association with the basophil constituents o f the nerve cells (Scharrer and Scharrer, '45). The evidence concerning the relation of secretory granules to one of these basophil substances, namely, nuclear chromatin, has already been discussed in some detail (Palay, '43). The concept will be further documented in this paper by a study of the Nissl substance in secreting nerve cells.
MATERIAL AND METHODS
The cells investigated here a r e those of the nucleus preopticus and nucleus lateralis tuberis in the teleost fishes Ameiurus nebulosus, Noturus Fundulus heteroclitus, Centropristes striatus, and Tautoga onitis ;3 of the nucleus preopticus in the amphibians Bufo terrestris and Bufo americana; of the nuclei supraopticus and paraventricularis of the banded water snake, Lapemis h a r d ~i c k i i , ~ and of the d o g z The standard method for the study of the relations between secretory material and Nissl substance was as follows : Whenever possible a cannula was inserted into the heart of the anesthetized animal, and the blood was washed out with plain Zenker's solution. Next Zenkerformol was injected. Perfusion of the brain with the fixing fluid was in this way maintained for periods up to 15 minutes. Then the brain was removed and left in Zenker-formol for 6 to 12 hours, after which time it was washed in running water for 24 hours. The material was embedded This study was aided by a grant to Western Reserve University from the Rockefeller Foundation. 2 These fishes were collected a t the F. T. Stone Laboratory a t Put-In-Ray, Ohio. 3 Theso species were obtained a t the Marine Biological Laboratory, Woods Hole, Mass. 4 The specimens weia collected a t Manila, P. I., in 1938. 5 A number of dogs wexe obtained from the Cornell farm through the kindness of the late Dr. C . R. Stockard.