THE GENERATIVE GLANDS 391 



physiological saline solution are very much weaker; and after 

 precipitation with acids the effects are very uncertain. Alcohol 

 seems to destroy the active principle. 



According to Dixon (1901) the active constituents of testicular 

 extract are nucleoprotein and certain toxic bases. Loisel arrived 

 at a similar conclusion, as the result of his experiments with the 

 ovaries and testes of animals of different species. 



THE INTERNAL SECRETORY TISSUE ELEMENTS OF 

 THE GENERATIVE GLANDS. 



Although the correlative chemical activity of the generative 

 glands has long been known, the question as to whether this 

 internal secretion is the property of histologically differentiated 

 portions of the organ and which tissue elements are the ones 

 concerned, is of very recent date. The problem first arose about 

 ten years ago, but has only latterly formed the subject of investi- 

 gation. It was very generally assumed, though upon no very 

 definite grounds, that the secretory elements of the sexual glands 

 performed a double function ; that they elaborated the specific 

 external secretion, which w 7 as carried off by the excretory ducts; 

 and that they also produced specific substances, which were con- 

 veyed by the lymphatics or the vessels into the general circulation, 

 and which became active in distant parts of the organism. The 

 genital glands were regarded as typical instances of glands with 

 two surfaces, in which the epithelial cells elaborate both the 

 internal and external secretions. In 1906, Nussbaum adopted the 

 theory that the generative portion of the testis is the site of pro- 

 duction of the hormone. The coincidence of the development of 

 the rutting organs with the most rapid development of the sper- 

 matic cells, suggested that it was the secretion of the spermato- 

 gonia, namely, the spermatides, which at the rutting season sup- 

 plied the impulse to the development of the seminal vesicles and 

 other rutting organs. 



It had long been known that, in addition to the seminiferous 

 tubules, the testis contained other morphological elements, but 

 owing to the nature of their genesis and structure, these were not 

 suspected of having an internal secretory function. It was not 

 until after the most searching investigation in comparative 

 morphology, chiefly by Bouin and his co-workers, that the 

 biological differentiation of the elementary constituents of the 

 male sexual gland was recognized. 



The situation in regard to the internal secretory element of 

 the ovary was more favourable. In this case also, it was at first 

 assumed that a double secretory function was performed by the 

 generative portion of the gland ; but the persistence of the 

 Graafian vesicle after the completion of ovulation suggested that 

 the internal secretory function of this organ was not simultaneous 



