AND ON THE LAWS OF ITS FUNCTION. 301 



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

 full of nucleated cells, and situated more towards 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 contents 

 of the vesicles are in various stages of development. 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 in- 

 cluded cells have begun at a certain part of the vesicle to elongate into cylinders, 

 with slightly rounded extremities. In others the cylindrical elongation has taken 

 place in all the included cells, with the exception of a few, which still retain the 

 rounded form, at a spot opposite to that part of the vesicle in which the change 

 commenced, and at the same time it may be observed, that the cylindrical cells 

 have become arranged in a spiral direction within the parent vesicle. Lastly, 

 Vesicles exist in which all the cells are cylindrical, and are arranged within its 

 cavity in a spiral direction. 



The changes which occur in the included nucleated cells of the vesicle are 

 highly interesting. After the nucleus of each has become developed into a mass 

 of cells, the parent cell becomes, as has been stated, cylindrical. The change in 

 the shape of the cell is contemporaneous with the appearance of a spiral arrange- 

 ment of the included mass of cells. This spiral arrangement is also contemporane- 

 ous with an elongation of each cell in the mass, in the direction of the axis of the 

 parent cell. When the elongation has reached its maximum, the original mass of 

 included cells has assumed the appearance of a bunch of spirals, like cork-screws 

 arranged one with another, spiral to spiral. In particular lights the cylindrical 

 cell presents alternate spots of light and shade, but by management of the illumi- 

 nation, the included spiral filaments become evident; the light and shade is seen 

 to arise from the alternate convexities and concavities of the spiral filaments, com- 

 bined in a spiral bundle. 



In vesicles more advanced, the walls of the cylindrical cells have become at- 

 tenuated. 



In other vesicles the diaphragms across their necks have dissolved or burst, 

 the bundles of spiral filaments float along the ducts of the gland, or separate into 

 individual spiral filaments. These filaments are completely developed sperma- 

 tozoa, pointed and filamented at both extremities, thicker and spiral in the middle. 



In the centre of the lobe where the smaller ducts meet to form the principal 

 duct, there is a mass of grey gelatinous matter through which the ducts pass. This 

 gelatinous matter consists of a number of cells lying between the converging ducts, 

 and from their peculiar appearance not presenting the usual nuclei. I am in- 

 clined to believe that they are either vesicles which have never become developed 



