COURSE OF NORMAL BIRTH 65 



in such cows, irrespective of the objections raised by the 

 owner. 



3. Falling in of the Flanks.— This is very plainly visible 

 laterally to the transverse processes of the lumbar vertebrae 

 and behind the last ribs. The contour of the lumbar vertebrae 

 aud sacrum appears much sharper. 



4. The Discharge of Mucus from the Vulva. — The cervix 

 uteri closes because its plicated folds come together. By the 

 secretion of a glairy, viscid white mucus, depositing itself like a 

 stopper upon these folds, the uterine opening is firmly guarded. 

 As a result of a very limited dilatation of the cervix uteri one or 

 two days before birth, this glairy mucus begins to lose hold, 

 and often appears in long and thick filaments at the vulva. 

 Occasionally this mucus is slightly red in color, caused by a 

 little blood from the chorion and some of the accessory coty- 

 ledons near the internal uterine opening. 



5. Swelling of the Vulva.— Physiological tumefaction of the 

 vulva occurs in the last days of pregnancy. It is caused by an 

 active hypersemia, reflexly instituted by the ovaries. This 

 swelling is not always present. In some cows it is wanting 

 while present to a great extent in others, and termed cedema 

 of the vulva. 



The preliminary or preparatory stage is followed by dila- 

 tation of the os uteri. The cow, which up to this time stood, 

 or laid down from time to time, becomes uneasy, paddles 

 behind, whisks the tail, defecates and micturates frequently 

 and in small quantities, lies down and rises often. The uterine 

 contractions, previously quite weak, now increase in intensity ; 

 now and then a throe is assisted by the abdominal muscles. 

 The presence of the dilatory throes is recognized by the clonic 

 contractions of the perinseum; the muscles which retract the 

 superior wall of the vagina when the tail is fixed, are also 

 actively concerned. During these contractions of the uterus 

 the cervix uteri becomes dilated. What causes dilation of the 

 os uteri ? In the first place, the contractions of the uterus, 

 cervix and vagina. The dilatation thus affected, and which 

 might be termed an active one, is nevertheless limited and far 



