POSITION OF THE HUMAN SEXUAL ORGANS. 419 



In the male Mammal also, a similar coalescence of the 

 lower portion of the Miillerian and Wolffian ducts takes 

 place. In this case also, these ducts form a single " sexual 

 cord " (Fig. 325, </), which likewise opens into the original 

 urinary sexual cavity (sinus urogenitalis'), which develops 

 from the lower part of the urinary bladder (v). While, 

 however, in the male Mammal the Wolffian ducts develop 

 into the permanent sperm-ducts, only very slight traces of 

 the Miillerian ducts remain as rudimentary organs. The 

 most remarkable of these is the " male uterus " (uterus 

 masculinus), which originates from the lowest, coalescent 

 portion of the Miillerian ducts, and which is homologous 

 with the female uterus. It forms a small flask-shaped 

 vesicle, entirely without physiological significance, which 

 opens into the urinary tubes between the two sperm-ducts 

 and the prostatic lobes (vesicula prostatica). 



The internal sexual organs in Mammals undergo veiy 

 peculiar modifications in point of position. At first the 

 germ-glands, in both sexes, lie deep down in the ventral 

 cavity, on the inner side of the primitive kidneys (Figs. 

 320, g, 321, &), attached to the vertebral column by a short 

 mesentery (in the male, the mesorchium; in the female, 

 mesovariuni). It is only, however, in Monotremes that this 

 original position of the germ-glands is (as in lower Verte- 

 tebrates) permanent. In all other Mammals (Marsupials as 

 well as Placentals) these glands quit their place of origin 

 and make their way more or less downward (or towards the 

 posterior extremity), following the course of a cord which 

 extends from the primitive kidney to the groin region of 

 the abdominal wall. This is the groin-cord of the primitive 

 kidney; in the male, the "Hunterian guiding-cord" (guber- 



