28 SECRETING STRUCTURES. * 



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 contemporaneous 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 in- 

 cluded 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 illumination, the in- 

 cluded spiral filaments become evident; the light and shade is 

 seen to arise from the alternate convexities and concavities of the 

 spiral filaments, combined in a spiral bundle. 



In vesicles more advanced, the wall of the cylindrical cells 

 have become attenuated, 



In other vesicles the diaphragms across their necks have dis- 

 solved 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 spermatozoa, pointed 

 and filamentous 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 inclined to believe that they are either vesicles which have 



