TREATMENT OF BREEDING COWS. 229 



"Now, an ingenious explanation of the phenomenon has 

 recently been offered by Mr. M'Gillavray, of Iluntly. 'When 

 a pure animal of any breed (says Mr. M'Gillavray,) has been 

 pregnant to an animal of a different breed, such pregnant animal 

 is a cross ever after; the purity of her blood being lost, in conse- 

 quence of her connection with the foreign animal;' and again: 

 ' If a cow, say of the pure Aberdeenshire breed, is in calf to a 

 bull of the short-horn breed, (known as the Teeswater breed,) in 

 proportion as this calf partakes of the nature and physical char- 

 acters of the bull, just in proportion will the blood of the cow 

 become contaminated, and herself a cross, forever incapable of 

 producing a pure calf of any breed.' 'It is maintained, there- 

 fore, (Mr. M'Gillavray adds,) that the great variety of nonde- 

 script animals to be met with, are the result of the crossing 

 system; the prevailing evil of which is, the admission of bulls 

 of various breeds to the same cow, whereby the blood is com- 

 pletely vitiated.' 



"This theory, of course applies only to that class of animals 

 (the mammalia) where the female is provided with a womb, and 

 has her offspring lodged there for a time. And in order to the 

 better understanding of the theory, attention is requested to the 

 following considerations: By the formation of the after-birth 

 (placenta,) a connection is established between the mother and 

 the living creature (foetus) in her womb, through which the 

 latter is continually drawing supplies from the mother's blood, 

 for its growth and maintenance. But there are good grounds 

 for believing that, through the same channel, the mother is as 

 constantly (though, doubtless, in much less quantity) abstracting 

 materials from the blood of the foetus. Now, is it all unrea- 

 sonable to suppose that the materials in question may be charged 

 with (or have inherent in them) the constitutional qualities of the 

 foetus, and that, passing into the body of the mother, and mixing 

 there with the general mass of her blood, they may impart those 



