128 Diseases of the Genital Organs 



rest upon the palpation of two fetuses, and there is no cer- 

 tainty whether they are to present alike or alternately. 

 Generally they alternate ; one presents cephalically and the 

 other caudally. In eampylorrhachis and schistocormus re- 

 flexus, however, we meet with a single fetus presenting 

 both by its cephalic and caudal ends. Double monsters may 

 also be met, confusing the examiner. In unicornual twins, 

 the examiner faces great difficulty. Almost, if not always, 

 they lie end to end — either head to head or tail to tail — caus- 

 ing an enormous elongation of the gravid horn which 

 reaches, at the close of pregnancy, double the length of the 

 antero-posterior diameter of the abdominal cavity, necessi- 

 tating the doubling of the uterus upon itself, as in the bitch. 

 Then the fetuses lie side by side, with two uterine walls be- 

 tween them and their contact ends lying against the dia- 

 phragm of the mother. Their free ends — two heads or two 

 tails — lying side by side, are directed toward the pelvis. 

 The basal fetus presents on a line with the long axis of the 

 cervix ; the fetus occupying the ovarian end of the horn lies 

 lateral to the basal fetus, on the side of the ovary of preg- 

 nancy. That is, if unicornual twins are in the right horn, 

 the basal fetus presents with its head or tail towards the 

 cervix, and on the right of this lies the other fetus, present- 

 ing by the same part but lying to the right of the cervix. 

 The ovary may now be pushed toward the pelvis and its two 

 corpora lutea should be palpable. On the left the non- 

 gravid horn would be palpable. In one cow about 60 days 

 pregnant, unicornual twins were quite securely diagnosable 

 by the presence of two typical corpora lutea in the ovary on 

 the pregnant side. That does not make twin birth neces- 

 sary. One embryo may perish and be absorbed but the diag- 

 nosis is still important because the other embryo may be a 

 "freemartin", or neuter, though born singly. If a good 

 diagnosis of twin pregnancy has been made, a single birth 

 follows, and the offspring is apparently a female, its sex 

 may well be doubted. 



