Repellers and Repulsion 595 



amount of force which is appHed. In some cases it is essential to 

 fix the animal'.s body so that it shall not be drawn from its posi- 

 tion instead of the fetus being extracted, while in other cases it 

 is necessary that the body of the parent be fixed in order to per- 

 mit of the traction being applied in the desired direction. 



As a general rule, when severe traction is applied the animal 

 assumes the recumbent position, and, when the fetus is well ad- 

 vanced in the pelvic canal, it may be necessary to in some way 

 fasten the posterior part of the body of the mother so that, when 

 the traction is directed toward her feet, she is not constantly 

 moved from her position. In order to overcome this movement 

 of the body of the mother, we may in the mare fix a rope to the 

 tail and, by attaching it to a solid object, prevent the constant 

 slipping of the body in a ventral direction. In either the cow or 

 the mare, a long rope may be passed between the hind limbs or 

 around the buttocks somewhat below the vulva and then attached 

 to some solid object beyond the dorsum of the mother in such a 

 way as to prevent her gliding in a ventral direction. 



Repellers and Repulsion. 



In obstetrical operations it frequently becomes essential that 

 the fetus be pushed back into the uterine cavity or the abdomen , 

 in order that room may be obtained in which to make certain 

 changes in the position of parts or to carry out other operations 

 which may be essential to the extraction of the fetus. This pro- 

 cedure we know as repulsion or retropulsion. It may be carried 

 out in a variety of ways, and naturally the most primitive method 

 is that of pushing the fetus backward by means of the operator's 

 hand. This most primitive and simple of all methods has great 

 advantages over the others, especially because the force can be 

 applied with intelligence and safet}'. 



It is the most effective means for bringing about changes in 

 the location and direction of the fetus, because the force may be 

 constantly applied at the proper angle and may be at once modi- 

 fied according to any changes in the position of the fetus during 

 the progress of the operation. 



Manual repulsion has the great disadvantage that it places upon 

 the operator the full burden of a more or less difificult task and 

 makes a demand upon his physical resources, which may later be 

 sorely needed for the accomplishment of other important opera- 



