IV PREFACE. 



ing of the facial sinuses had been de41t with at length in 

 order to fully and clearly describe the author's method of 

 operating ; a new operation for poll evil has been inserted 

 and there has been included a description of some of the 

 most important embryotomy operations as they are carried 

 out in the laboratory by means of freshly killed, new born 

 calves which are placed in the position described, in the arti- 

 ficial uterus of a specially prepared skeleton . 



Generally but one method of operating is described, the 

 one chosen being that which in the author's experience has 

 proven the most valuable in actual practice, and no opera- 

 tion has been introduced purely for practice but each one 

 has been tested and known to have practical value. 



Where two methods of operating are given, they are 

 inserted because each has definite points of superiority over 

 the other and one method may be specially applicable in a 

 given case, another in a different patient where the same 

 operation is to be performed as for example, a milk cow is 

 best spayed through the vagina while a heifer must be 

 operated on by an incision through the abdominal walls. 



Considerable stress has been laid upon the surgical an- 

 atomj' of the parts involved in each operation ; some uses of 

 the various operations are mentioned ; some of the chief 

 dangers of each are pointed out and in some cases references 

 to literature upon the operation or the diseases for which the 

 operation is designed, are cited. 



The figures in the text except Nos. 5, 10 and 11, and the 

 Plates Nos. I, 11, VIII, X, XII, XIV, XVII, XVIII, 

 XXI, XXII, XXIII, XXV, XXVIII and XXIX are from 

 Dr. Pfeiffer's Operations- Cursus ; Plate No. Ill was drawn 

 by Dr. C. F. Flocken, Bureau of Animal Industry, Wash- 

 ington, D. C, and the remaining Plates were drawn under 

 the direction of the author by Mr. C. W. Furlong, in- 

 structor in Industrial Drawing and Art in Sibley College, 

 Cornell University. 



W. Iv. WlI,I,IAMS. 

 Cornell University October, /goj. 



