42 ARTHUR ROBINSON. 



the ovary was carefully lifted up a sac was at once demonstrated, in 

 which the ovary lay, and on the wall of which the Fallopian tube 

 formed many convolutions. No opening into the sac was visible. 



In order that no small orifice might escape observation, a series of 

 animals was taken, and through the uterus and Fallopian tubes 

 injections, in some cases of coloured fluids, in others of air, were 

 forced. These injections entered and distended the ovarian sacs, 

 but in no case escaped from them into the peritoneal cavity. Thus 

 it was definitely proved that the only communication of the sac was 

 with the uterus through the Fallopian tube, and that there was no 

 opening from the sac into the peritoneum. 



As further proof, several ovaries were cut out, both from rats and 

 mice, together with the broad ligament, the tip of the cornu uteri, 

 and the Fallopian tube in each case. These specimens were stained 

 with borax carmine embedded in paraffin, and a continuous series of 

 sections was taken from them by means of the Cambridge rocking 

 microtone. 



When the sections were examined, it was found that the ovary 

 lay in a sac (Plate IV., Fig. 5), the wall of which became continuous 

 with the ovary and the broad ligament at the hilus of the ovary. 



The sac wall consisted of fine fibrous tissue : both surfaces of the 

 wall were covered with flattened, plate-like cells. The cells on the 

 outer surface of the sac wall were continuous with the general epi- 

 thelial lining of the peritoneal cavity, and were in every way similar 

 to them. Those on the inner surface of the sac over its greater 

 portion were also similar in character, but as they approached the 

 hilus of the ovary their form began to change, becoming more and 

 more cubical, until by gradual transition they became transformed 

 into the germinal cells covering the free surface of the ovary. 



The wall of the ovarian sac was complete, except at the point of 

 entrance of the Fallopian tube. At this place the sac wall became 

 continuous with the outer wall of the Fallopian tube, the dilated 

 termination of which projected into the interior of the sac. 



There was thus demonstrated a sac completely surrounding the 

 ovary, shut off from the peritoneal cavity, and communicating at one 

 place with the lumen of the Fallopian tube. 



The same arrangement of parts was found present in rats three 

 days old, the only difference from the adult being as follows : — The 



