Bicornual Pregnancy 717 



depart from the body at right angles, or slightly recurved so as 

 to give the entire organ, consisting of the body and cornua, a 

 crucial form. It thus becomes possible for the fetus to develop 

 in such a position that the long axis of its body corresponds to 

 the combined long axes of the two uterine cornua ; that is, the 

 fetus develops partly in each of the two cornua, with its body 

 crossing the uterine body at its anterior extremity, so that the 

 fetus fundamentally occupies a position with its long axis trans- 

 verse to that of the mare. 



How often this may occur in the mare, we do not know. In 

 our contribution above quoted, we recorded four cases, to which 

 we may add the four case reports of Tapken and one of Pauli. 



It is a well known fact, to all who have had extensive obstetric 

 practice in mares, that it is not rare for the foal to present trans- 

 versely. This is in sharp contrast to cattle obstetrics, where 

 transverse presentation is very rare. Among these presentations, 

 except those cases which we now, have defiaitely under con- 

 sideration, it is impossible to determine how many of them may 

 have developed transversely, and consequently at the time of 

 birth presented transversely. While veterinary obstetrists may 

 deny the posssibility of bicornual development, our cases, fully 

 verified by post mortem examination, show that it actually occurs, 

 and not very infrequently. The established facts do not forbid 

 our assuming that some of the other fetuses which present trans- 

 versely ma3' have been developed in the transverse position. 



In the cases now under consideration, the embr5-o apparently 

 forms in each case in the transverse presentation, with its ventral 

 surface presenting toward the os uteri, and later revolves upon 

 its long axis, so that it finally rests in a dorsal tran.sverse presen- 

 tation instead. 



In its earlier stages, the embryo curves very markedly ven- 

 tralwards, and this ventral curvature continues to a consider- 

 able degree throughout gestation. Since the cornua of the uterus 

 leave the body at right angles or slightly recurved, the embryo 

 may well develop with either its dorsal or ventral surface facing 

 the OS uteri, although, so far as investigations upon this point 

 carry us, only those cases have been recognized as bicornual 

 development which have begun their development with their 

 ventral surface presenting toward the pelvis. 



