128 MUNSON. [Vol. XV. 



On the expansion of the ovarian tube, this lateral pressure is 

 relieved and the cells assume a more spherical form. 



The size of the epithelial cells is subject to considerable 

 variation, and the thickness of the epithelium also varies within 

 considerable limits. This is due, in part at least, to the varying 

 lateral pressure on the cells, and on the amount of folding of 

 the tunica propria ; for, where the tube is distended, the epithe- 

 lium may become flattened into what appears to be a mere thin 

 protoplasmic layer with scattered nuclei. In other portions of 

 the same tube, where the folding and lateral pressure still exists, 

 the epithelium appears to have considerable thickness. In all 

 cases, however, it consists of a single layer of cells. 



This epithelium can always be distinguished from all other 

 tissues by its glassy transparency, except at certain stages, 

 when the cell protoplasm becomes filled with secretion granules. 

 The minute structure of the protoplasm assumes different ap- 

 pearances, as the cells are seen to be compressed or expanded. 

 The distinctness of cell boundaries also varies with the amount 

 of lateral pressure. Where the tube is expanded, and the cells 

 are more than usually flattened, cell boundaries are difficult 

 to make out. The cytoreticulum of one cell area seems to be 

 continuous with the cytoreticulum of neighboring cell areas, the 

 nuclei in each affording landmarks. Careful examination of this 

 protoplasm seems to indicate that the various nuclei are con- 

 nected by means of this system of cytoplasmic fibrils. These 

 fibrils can be seen to be massed into strands or bundles. The 

 bundles, however, can be analyzed into finer fibrils connecting 

 larger microsomes. An increase of the magnifying power shows 

 that the meshes of these fibrils are again traversed by still finer 

 fibrils. At each node there is always a stainable, spherical 

 enlargement, which usually diminishes with the fibril under con- 

 sideration. The whole has thus the appearance of a network 

 within a network, through a considerable series of gradations 

 in size, both of the fibrils and their nodal enlargements. There 

 appears to be no limit, except that which the microscope 

 imposes, to this continued decrease in the size of the fibrils, 

 the size of the stainable nodes, and the size of the enclosed 

 meshes. 



