DIAMETER OF THE TUBA. 



always shorter than the ampulla, although the relative length 

 of the two varies in different species of Mammals. 



In the Fowl, as in almost all Birds, only one oviduct is 

 present, that, namely, of the left side. The rudiments of 

 a pair of female sexual organs are, indeed, originally present, 

 but in the course of development that of the right side 

 usually disappears* This passes downwards, pursuing a 

 more or less tortuous course in front of the left kidney, to the 

 cloaca. At the lowest part it suddenly dilates, and becomes a 

 uterus. It is fixed in its position by a peritoneal fold. 



In Amphibia the oviduct again becomes double. In Bufo 

 cinereus it extends upwards over the root of the lung, and is at 

 this its abdominal extremity, for about eight to ten millimeters, 

 fastened by means of a peritoneal fold to the posterior abdominal 

 wall. The upper part is very tortuous. At the lower end it 

 becomes suddenly wider, and terminates in a vesicular dilatation 

 which directly opens into the cloaca. 



The oviduct in Man and Mammals communicates by its 

 narrow ostium uterinum with the cavity of the uterus. In 

 Man this opening is at the upper part of the uterus, and is 

 so small that it will scarcely permit the passage of a fine 

 bristle. It enlarges as it approximates its external orifice 

 the ostium abdominale but contracts again at the orifice itself. 

 Haller maintained that after its dilatation it again underwent 

 constriction near its middle, and Weber f held the same opinion. 

 Meckelif gives the diameter of the ostium uterinum at half a 

 millimeter, that of the ostium abdominale at three to four 

 millimeters. Krauseg estimates the diameters of the ostium 

 uterinum at one-fifth to one-fourth of a millimeter, and that of 

 the widest portion in front of the ostium abdominale at two 

 millimeters. Huschkej) gives as much as three to four milli- 

 meters for the diameter of the tube at this latter point. 



In Man the Fallopian tube dilates to form a funnel at the 



* Stannius, Lehrbuch der veryleichenden Anatomic der Wirbelthiere, 

 p. 333. 



t Band iii., p. 616. 

 Band iv., p. 516. 

 Bandi., p. 559. 

 || Loc. dt., p. 470. 



K K 2 



