168 Proceedings of the Roi/al Sucieti/. 



purple of Janthina and Aplys'ia, bile in an extensive series of ani- 

 mals, urine in the moUusk, milk, &c. 



The wall is believed by the author to be the part of the cell en- 

 gaged in the process of secretion. The cavity contains the secreted 

 substance, and the nucleus is the reproductive organ of the cell. A 

 primitive cell engaged in secretion is denominated by the author a 

 primary secreting cell ; and each cell of this kind is endowed with 

 its own peculiar property, according to the organ in which it is situ- 

 ated. The discovery of the secreting agency of the primitive cell 

 does not remove the principal mystery in which the function has al- 

 ways been involved ; but the general fact that the primitive cell is 

 the ultimate secreting structure is of great value in physiology, in- 

 asmuch as it connects secretion with growth as phenomena regulated 

 by the same laws ; and explains one of the greatest difficulties in the 

 science, viz. wliy a secretion ilows from a free surface only of a se- 

 creting membrane, — the secretion exists only on the free surface en- 

 closed in the ripe cells which constitute that surface. 



The author then proceeded to the consideration of the origin, the 

 development, and the disappearance of the primary secreting cell — 

 a subject which necessarily involved the description of the various 

 minute arrangements of glands and other secreting organs. After 

 describing the changes which occur in the testicle of Squalus cornu- 

 bicus, when the organ is in a state of functional activity, and in the 

 liver of Carcinas mccnas, it was stated that these were selected as 

 examples of two orders of glands denominated by the author vesicu- 

 lar and iollicular. 



The changes which occur in the first order consist in the forma- 

 tion and disappearance of closed vesicles or acini. 



Each acinus might be, first, a single cell, denominated by the 

 author the primary or germinal cell ; or, secondly, of two or more 

 cells enclosed in the primary cell, and produced from its nucleus. 



The enclosed cells he denominates the secondary cells of the aci- 

 nus, and in the cavities of these, between their nuclei and cell-ivalls, 

 the peculiar secretion of the gland is contained. The primary cell 

 with its included group of cells, each full of secretion, is appended 

 to the extremity or side of one of the terminal ducts, and conse- 

 quently does not communicate with that duct, a diaphragm formed 

 by a portion of the primary cell-wall stretching across the pedicle. 

 When the secretion in the group of included cells is fully chibo- 



