200 Cattle Problems. 



continued distention as when first relaxed by excessive en- 

 gorgement.* 



But a furtlier and strong auxiliary influence that inten- 

 sifies the engorgement of the udder-supply arteries, is 

 found in the engorgement of the milk-glands, both in 

 cows, and heifers that have never been milked. In such 

 cases there is the storage of their twelve-hour, or half-day 

 yield, altogether in their udders ; their arteries being sim- 

 ilarly engorged ; and a similar accumulation of milk in the 

 udders, and in the blood-supply in the udder-supply ar- 

 teries of heifers takes place long before they calve. The 

 engorgement of the milk-glands in these self-evident ways 

 arrests the flow of artery-blood before it can enter the milk 

 glands ; this engorgement in the glands and in their supply 

 arteries continuing for weeks in some heifers, and being re- 

 lieved but once in twelve hours in cows at the pail. The 

 "back setting" as millers call it, of the blood from this 

 cause must extend far back in the arteries, condensing the 

 blood, and intensifying the pressure of extreme engorge- 

 ment in great degrees and so thinning down the substance 

 of the artery-walls in certain proportion to the increase in 

 conveying size of their tubes, or in the degree correspond- 

 ing to that of their further engorgement and expansion, 

 from this back-setting of the blood. 



This must be the necessary effect of too abrupt or ex- 

 tremely rapid artery expansion, intensified by back-setting 

 of the blood. And any rate of expansion that is more 

 rapid than the increase of thickness and strength in the 

 artery walls by nutrition from the circulation, is too rapid, 

 and therefore excessive. 



In such cases, the artery walls are weakened by expan- 

 sion faster than they are strengthened by nutrition, be- 

 coming in a little while too weak to perform their natural 



*Tho cflcct of engorgement In thinning the artery walls is illustrated in 

 cuts, also given in table. 



