Abortion in Cows. 213 



Over 60 per cent of dairy district abortions occur in the 

 stranger class of cows, or newly brought-in cows of mod- 

 erate yield, in which the yield, of any previous extent, is 

 much more rapidly increased than in cows raised by dairy- 

 men; see text. The rapid rate of engorgement, and the 

 thinning of the artery-walls, in many new cows, is shown 

 at r. r.. Fig. 6 ; the relaxed condition of the artery-walls, 

 of course, continuing from continued engorgement, as 

 shown by the dotted lines in the same Fig. Home-raised 

 cows are sometimes tempted to eat more feed than is usual, 

 by doing which they increase their blood, and udder-supply 

 artery-size, in correspondence to the increase in }'ield, as 

 shown at ;-. r., Fig. 7 — which may be 5 to 10 per cent — 

 and this may lead to artery relaxation and abortion in 

 some of them. 



Cows are, of course, more liable to artery relaxation, 

 and less likely to recover lost contractile power in their 

 arteries, after mature age and growth, than when they are 

 young and more vigorous. 



