CHAP, i.] FEMALE ORGANS. 361 



gliding movements of the mouth of the tube over the ovary have 

 been observed in animals. It has, however, been asserted that the 

 turgescence of the tube does not occur until after the ovum has 

 become safely lodged in the tube, arid it is argued that the ovum 

 is carried in the proper direction by currents set up by the action 

 of the ciliated epithelium lining the tube, currents whose direction 

 and strength seem, as shewn by experiment, to be adequate to 

 carry into the uterus particles present in the peritoneal fluid ; and 

 the groove in the ciliated surface of the ovarian fimbria especially 

 connected with the ovary, suggests itself as the natural path for 

 the ovum. 



Arrived in the tube, the ovum travels downwards very slowly, 

 by the action probably of the cilia lining the tube, though possibly 

 its progress may occasionally be assisted by the peristaltic con- 

 tractions of the muscular walls. The stay of the ovum in the 

 Fallopian tube may extend to several days ; the channel, as we 

 have seen, is a narrow one, especially at the entrance into the 

 uterus. The escape of the ovum is followed by changes in the 

 follicle and rest of the ovary, which we have already described. 



936. The discharge of the ovum is accompanied, or rather, in 

 part at least preceded, not only by a congestion or erection of the 

 ovary and Fallopian tube, but also by marked changes in the 

 uterus ; and it is to these that the obvious phenomena of men- 

 struation are due. While the whole organ becomes congested 

 and enlarged, the mucous membrane undergoes special changes. 

 Not only are the blood vessels and lymphatic vessels and spaces 

 distended with their respective fluids, and the glands turgid so 

 that the whole membrane becomes red, thick and swollen, but also, 

 according to some observers, a proliferation of the epithelial cells, 

 and to a certain extent of the connective tissue elements, takes 

 place. The change does not extend to the cervix, which thus presents 

 a contrast to the body of the uterus. From the distended blood 

 vessels blood escapes not only into the dermic connective tissue 

 between the glands but also into the lumina of the glands and 

 especially on to the free surface of the mucous membrane, the 

 extravasation coming apparently chiefly from the capillaries and 

 being due to a kind of diapedesis ( 184) rather than to rupture. 

 In this way there takes place from all parts of the swollen surface 

 a haemorrhagic discharge, often considerable in extent, which 

 together with a mucous secretion furnished by the glands and 

 containing a number of cells resembling leucocytes, constitutes 

 the menstrual or catamenial flow. The blood as it passes through 

 the vagina becomes somewhat altered, probably by the influence of 

 the other constituents of the discharge, and when scanty coagulates 

 but slightly ; when the flow however is considerable, distinct clots 

 may make their appearance. The swollen and changed mucous 

 membrane then undergoes a rapid degeneration, and is shed, 

 passing away generally as mere detritus but sometimes in distinct 



