No. 2.] THE OVARIAN EGG OF LIMULUS. 137 



XIV, Figs. 33, 35), and on first observing them one might 

 easily receive the impression that they are fusing. The dis- 

 tinctness of the outlines of the nuclei, however, renders it easy 

 to make out almost equally distinct cell boundaries. The pro- 

 toplasm of each cell is reduced to a thin rim, in which can be 

 seen the few fibers of the cytoreticulum, often not exceeding 

 three or four in number. Owing to the pressure the cell 

 body becomes pentagonal, each side being straight and 

 closely applied to a corresponding surface of a neighboring 

 cell. Yet the cell boundaries are distinct. 



These groups of cells can be seen in both transverse and 

 longitudinal sections of the tube. In either case the general 

 appearance of the group is the same. In transverse sections 

 of the tubes only one group can be seen ; while in longitudinal 

 sections several groups can be seen at regular intervals along 

 the tube. 



In such sections the epithelium on the side opposite the 

 group has only about one-fourth of the thickness of what it has 

 on the side where the groups are situated. This same relation 

 holds also in transverse sections, and it is due to the fact that 

 each group pushes into the lumen of the tube, so as to obliter- 

 ate it at that point (PI. XIV, Fig. 35). But in the larger 

 larvae, where the epithelial cells have become considerably 

 elongated in the direction of the lumen, these groups of cells 

 are more frequently enclosed by the protoplasm of neighbor- 

 ing cells as if they had originated beneath them, and pushed 

 their way partly up between them. The group, therefore, does 

 not project freely into the lumen. 



In the larva these cells, when they assume the resting stage, 

 acquire the general appearance of the neighboring epithelial 

 cells. They, however, remain grouped together for some time. 



After a certain number of divisions (the exact number can- 

 not be made out), one of these cells, usually one lying close to 

 the basement membrane, increases in size more rapidly than 

 the others. Without assuming the characteristic chromatin 

 network, and chromatin coil of the preceding stage, the nucleus 

 enlarges, the chromatin becomes divided into irregular gran- 

 ules that become distributed in an irregular fashion along a 



