CHAPTER V. 

 THE MILK MIRROR. 



Before attempting to discuss " Guenon's escutcheon theory" it i> 

 as well that we should understand what some authorities in veterinary 

 physiology apparently wish to infer with regard to the much debated 

 theory of milk secretion. They say: "The nervous system of the 

 cow is intimately associated with the production of milk. Very large 

 milkers, as a rule, show a more pronounced nervous tempciament than 

 animals of the beef type that secrete very little milk." 



According to these authorities, a nerve starts from the spinal cord 

 at the lower part of the loins, and divides in the pelvis into three 

 branches. One branch is distributed among the muscles of the ab- 

 domen, while the other two are distributed through the udder. In 

 this latter organ the nerves are divided, so that one blanch is asso- 

 ciated with the teat, another with the milk-cistern, while the third 

 permeates the lobules and alveoli. As the teats are worked by the 

 hand the nerves become irritated, causing their contraction and the 

 discharge of their contents. Animals noted as large milk producers 

 are usually found to have large arteries and veins connected with the 

 udder. The larger veins extend along the belly towards the heart, 

 while the smaller and more numerous ones are twisted, and extend 

 in no defined direction. 



It was by studying these arteries that led Guenon to follow up his 

 escutcheon theory. He discovered that the artery which supplies the 

 udder with blood also nourishes the skin of the escutcheon. Hence 

 there is reason for believing it to be an index of the blood which is 

 being furnished to the udder. 



The method has had, comparatively speaking, but a restricted 

 utility, though strongly endorsed by some investigators, who have pro- 

 nounced that the change in the growth of the hair in the posterior 

 region of the udder is caused by the action of the artery, \vhich is a 

 matter worthy of notice. 



We have, therefore, to take seriously into consideration when ex- 

 amining the milk mirror or escutcheon the nervous system as indicated 

 by the vitality observable, caused by the nerve of the spinal cord. In 

 this respect good judges often look for the large protruding eye, the 

 dished forehead, and the spine, without having any knowledge of the 

 cause of such good indications. 



The milk mirror or escutcheon has of late years been much dis- 

 cussed by dairymen, and the result, as in most of the other points in 

 connection with dairy cattle, seems to hinge on the grasp o'r other- 

 wise the view suddenly laid hold of by the parties for or against the 

 theory. In other words, there is a difference of opinion with re- 

 gard to the practical value of the system of classification and judging 

 of milk cows discovered and developed by Guenon, some being in- 

 clined to ridicule it as absurd, others to adopt it implicitly and follow 

 it out in all its details ; and still others and among this class we 

 generally find a very large number of the most sensib e and practical 

 judges of stock who admit that in the main it is correct, though they 

 discredit the practicability of carrying it out so far and so minutely 

 into detail as its author did. 



It may be remarked at the outset that the fact that the best of the 

 signs of a great and good milker adopted by Guenon arc generally 

 found united with the best forms and marks, almost universally ad- 

 mitted and practiced upon by good judges, gives, at least, some plausi- 

 bility to the >y>U'iii, while the importance of it, if it be correct, is 

 sufficient to demand a careful examination. 



256. 



