188 DISEASES OF CATTLE. 



opposed to the natural curvature of the passages; and, second, the 

 thickest part of the body of the calf (the upper) is engaged in the 

 narrowest part of the passage of the pelvis (the lower). Yet unless 

 the calf is especially large and the pelvis of the cow narrow, parturi- 

 tion may usually be accomplished in this way spontaneously or with 

 veiy little assistance in the way of traction on the limbs. If this can 

 not be accomplished, two courses are open : First, to rotate the calf as 

 wdien the back is turned to one side; and, second, to push back the 

 presenting fore limbs and head and search for and bring up the hind 

 limbs, when the presentation will be a natural posterior one. 



PRESENIATION OF THE HIND FEET W^TH THE BACK TURNED TO ONE SIDE 

 OR DOAVNWARD, 



These are the exact counterparts of the two conditions last de- 

 scribed, are beset with similar drawbacks, and are to be dealt with on 

 the same general principles. (PI. XVII, fig. 4.) With the back 

 turned to one side the body should be rotated until the back turns 

 toward the spine of the dam, and with the back turned down it must 

 be extracted in that position (care being taken that the feet do not 

 perforate the roof of the vagina) or it must be rotated on its own 

 axis until the back turns upward, or the hind limbs must be pushed 

 back and the fore limbs and head advanced, when the presentation 

 will be a natural anterior one. 



IMPACTION OF TWINS IN THE PASSAGE. 



It is very rare to have twins enter the passages together so as to 

 become firmly impacted. As a rule, each of the twins has its own 

 separate membranes, and as the water bags of the one will naturally 

 first enter and be the first to burst, so the calf which occupied those 

 membranes will be the first to enter the passage and the other will be 

 tliereby excluded. \^Tien the membranes of both twins have burst 

 without either calf having become engaged in the pelvis, it becomes 

 possible for the fore legs of the one and the hind legs of the other to 

 enter at one time, and if the straining is very Aaolent they may become 

 firmly impacted. (PI. XVIII, fig. 1.) The condition may be recog- 

 nized by the fact that two of the presenting feet have their fronts 

 turned forward, while the two others have their fronts turned back- 

 ward. If the four feet belonged to one natural calf, they would all 

 have the same direction. By means of this ditference in direction we 

 can easily select the two feet of one calf, place running nooses upon 

 them just above the hoofs or fetlocks, and have an assistant drag 

 upon the ropes while the feet of the other calf are pushed back. In 

 selecting one of the twins to come first several considerations should 

 have weight. The one that is most advanced in the passage is, of 



