266 Veterinary Obstetrics 



hymen persisting entirely across the inferior portion of the 

 vagina and extending upward and backward toward the vaginal 

 roof, but not reaching it. On attempting to breed the filly, it 

 was found that the stallion could not copulate on account of 

 some obstruction. As soon as the penis reached the region of 

 the hymen, progress was stopped and the stallion dismounted. 

 After several vain attempts at breeding, we were asked to ex- 

 amine the filly. We soon discovered that there was an opening 

 through the hymen at the superior portion and consequently 

 advised the stallion groom to see that the penis was pushed 

 upward along the roof of the vagina, by the hand. By this 

 means, copulation was successful and impregnation took place. 



In other cases which have been recorded in the cow, the 

 hymen has completelj' closed the genital passage and caused an 

 accumulation of uterine discharges in the vagina. In all such 

 cases, copulation is evidentlj' impossible until the membrane is 

 ruptured. 



Bands of a similar character are also found, at times, represent- 

 ing the embryologic median walls of the fused Miillerian ducts, 

 (see page 19) which have failed to atrophy and disappear com- 

 pletely, as is normal in the region of the vagina when the ducts 

 fuse properly. They may persist so completely as to constitute 

 essentially a double vagina. 



In all cases where copulation is interrupted in such a manner 

 as we have described, a careful search of the genital canal by the 

 veterinarian is demanded. In making this examination one is to 

 keep constantly in mind the embryologic development of the 

 organs and look carefully for persi.stent hymen, which may con- 

 stitute a transverse partition, as well as for bands representing 

 the persistent median walls of the ducts of Miiller, in the form of 

 longitudinal septa. These conditions should always be clearly 

 differentiated from any acquired disease or deformityof the parts. 



They are to be handled on general surgical principles and as a 

 rule offer but little difficulty in overcoming them. The narrow 

 bands representing either of these embryologic structures rarely 

 interfere with copulation and it is only when they are quite ex- 

 tensive that the process of coition is stopped. They may, as a 

 rule, be destroyed by rupturing with the hand or by severing 

 with a scalpel. 



