Positions of the Fetus 535 



l)ody, the position of the fetus in relation to the circumference of 

 the pubic inlet is not so important, although even here the fetus 

 is generally and most readily expelled in the dorso-sacral position. 



When the longitudinal presentation is posterior, instead of 

 anterior, the same modifications of position prevail and are sim- 

 ilarly designated. There is the dorso-sacral position, with the 

 dorsum of the fetus presenting toward the sacrum of the mother ; 

 the right and left dorso-ilial positions, with the dorsum of the 

 fetus directed toward the right or left ilial shaft of the mother ; 

 and the dorso-pubic , position, with the. dorsum of the fetus 

 directed toward the pubis of the mother. Some writers designate 

 these positions lum bo-sacral, lumbo-ilial and lumbo-pubic respect- 

 ively. 



Authors are not in accord upon the question of whether we 

 can properly consider anj"- position of the posterior presentation 

 normal in the large herbivora. Certain it is that only very, very 

 rarely is a calf or a foal born alive in the posterior presentation, 

 unless assistance has been promptly afforded and birth greatly 

 hastened. Whenever the fetal body has been so far expelled 

 that the fetal umbilicus has entered the pelvic inlet of the 

 mother and the umbilic cord is compressed between the pelvic 

 brim of the mother and the ventral wall of the fetus, the life of 

 the latter is at once threatened. It must quickly die from as- 

 phyxia unless very promptly expelled or extracted and permitted 

 to at once breathe. 



Precisely how long a fetus may live after the umbilic cord 

 becomes compressed between the pubis of the mother and the 

 body of the fetus, cutting off the fetal circulation, is not known 

 but it certainly cannot be for more than a few minutes. Some 

 authors have suggested that, if the circulation be thus inter- 

 rupted, the fetus at once inhales the amniotic fluid and thus 

 drowns itself. We have found no data to show us to what extent 

 this is true. It is evidently well-nigh impossible for such inhala- 

 tion of fluids to occur clinically, because, at the moment when 

 the strangulation of the cord occurs, the chest of the- young 

 animal is so tightly impacted in the inlet of the pelvis of the 

 mother that it is difficult to understand how amniotic fluid! or 

 anything else could be inhaled. When the chest has passed 

 through the birth canal, the head at once follows, and. it only re- 



