No. 2.] THE OVARIA.V EGG OF LIMULUS. 133 



seen in all sections, but, in favorable cases of tangential-longi- 

 tudinal sections, they appear to be arranged in a chain between 

 the lymph spaces. Sometimes it appears as if every other cell 

 belonged to opposite walls of the contiguous lymph spaces ; 

 and, being separated considerably, they alternate in such a way 

 as to appear to be a single chain of cells. It seems highly prob- 

 able that these cells give rise to the future ovarian tubes. 



I have not been able to trace the origin of the tubes, but 

 it seems to be somewhat as follows : by division these cells 

 give rise to chains of cells ; which chains, consisting of per- 

 haps four cells in cross section (possibly enclosing a cavity or 

 lumen), take the direction of the lymph sinuses between whose 

 walls they lie. But the walls of these lymph spaces intersect 

 in various ways and at nearly all angles. The chains or tubes, 

 therefore, also intersect in the same way, and thus a network 

 is established. The cells continue to proliferate, and the num- 

 ber of cells in cross section increases. Such minute ovarian 

 tubes, from four to six cells in cross section, can be seen in 

 young animals from four to five inches. 



With the increase in cross section the peritoneal walls 

 between which the tubes lie become more and more separated ; 

 and these walls, originally closely applied as the boundaries of 

 lymph spaces, become the peritoneal mantle, or loose perito- 

 neal coat of the ovarian tubes of the adult animal. 



The cells of the rods early show an arrangement as far from 

 the common center of the long axis of the tube as space will 

 permit ; and thus a lumen early makes its appearance. Cells 

 can be seen to continue dividing by karyokinesis, and, becom- 

 ing pushed into the lumen, temporarily obliterate it. In 

 animals from five to seven inches the lumen of the tube is 

 already well established. The cross section of the tubes does 

 not increase equally in all tubes, and their development takes 

 place more rapidly on the dorsal than on the ventral side. 



\V!ien the cells are sufficiently numerous in cross section to 

 constitute a tube, they are seen to be surrounded by a second 

 membrane, the tunica propria. At this early stage the tunica 

 propria is closely applied to the original peritoneal coat, 

 although they are easily seen to be entirely distinct, the peri- 



