SECRETING STRUCTURES. 27 



when the animal is in a state of sexual vigour, the following 

 arrangements of structure present themselves. 



The gland consists of a number of lobes separated, and at the 

 same time connected by a web of filamentous texture, in which 

 ramify the principal blood-vessels. 



The lobes, when freed from this tunic, present on their surface 

 a number of vesicles. "When the gland is dissected under water, 

 and one of the lobes is raised out of its capsule, an extremely 

 delicate duct is observed to pass from it into the substance of the 

 capsule, to join the ducts of the other lobes. 



When a section is made through one of the lobes, it becomes 

 evident that the vesicles are situated principally on its exterior. 



If a small portion be macerated in water for a few hours, and 

 dissected with a couple of needles, there are observed attached to 

 the delicate ducts which ramify through the lobe vesicles in all 

 stages of developement. These stages are the following: 1st, 

 A single nucleated cell attached to the side of the duct, and pro- 

 truding, as it were, its outer membrane. 



2d, A cell containing a few young cells grouped in a mass 

 within it ; the parent cell presenting itself more prominently on 

 the side of the duct. 



3d, A cell attached by a pedicle to the duct, the pedicle being 

 tubular, and communicating with the duct ; the cell itself being 

 pyriform, but closed and full of nucleated cells. 



4:th, Cells larger than the last, assuming more of a globular 

 form, still closed, full of nucleated cells, and situated more to- 

 wards the surface of the lobe. 



5th, The full-sized vesicles already described as situated at the 

 surface of the lobe. These vesicles are spherical, perfectly closed ; 

 that part of the wall of each which is attached to the hollow 

 pedicle forms a diaphragm across the passage, so that the vesicle 

 has no communication with the ducts of the gland. The con- 

 tents of the vesicles are in various stages of developement Those 

 least advanced are full of simple nucleated cells ; in others, the 

 included cells contain young cells in their interior, so that they 

 appear granular under low powers ; in others, the included cells 

 have begun at a certain part of the vesicle to elongate into 

 cylinders, with slightly rounded extremities. In others the 



