iJA.STkATlON. 



7(31 



examination commonly employed. Under such circumstances a special 

 speculum is introduced in a closed condition, being afterwards opened 

 and dilated to the required extent. 



Before inserting the speculum, however, the genital passages should 

 be cleaned, and the speculum itself smeared with vaseline. It pene- 

 trates readily with moderate pressure. 



Heifers and similar animals require a special (small) instrument 

 (Fig- 318). 



In certain circumstances, moreover, it is preferable to use retractors, 

 with which local examination is easier. These can be applied at either 

 side of the vagina and drawn apart, thus ex- 

 posing the depths of the genital tract. 



CASTRATION OF THE COWf. 



The operation of castrating' the cow is 

 very old, and was mentioned by both Aristotle 

 and Pliny. Many other descriptions of it 

 have since been given. But more recently 

 the manual technique has been considerably 

 simplified and very fully described. 



Utility. — The operation is practised for 

 the cure of nympho-mania ; also to prolong 

 the period of milk-yielding and to facilitate 

 fattening. 



As regards nympho-mania, it is only of 

 value where the excessive excitement is due 

 to disease of the ovaries. 



Under ordinary conditions the secretion of 

 milk diminishes more or less, and becomes 

 very slight after eight or nine months from Fig. 318.— Vaginal speculum 

 calving. If, however, the cow is castrated for heifers. 



under favourable circumstances, lactation con- 

 tinues for several months, sometimes for several years, beyond this 

 period. It is said that castrated cows yield milk of a more constant 

 composition and richer in butter fat, casein, and mineral salts than 

 those which are not castrated, although the point cannot be said to have 

 been fully established. 



To obtain the best results the subjects should have attained their 

 maximum yield of milk and be from five to seven years old. The best 

 period is six weeks to two and a half months after calving. Neglect of 

 these considerations is liable to be followed by inappreciable, doubtful, 

 or bad results. 



