Hyper cernia. Congestion. 35 



heart and increased force of the blood flow (blood tension) In 

 such cases those organs become congested in which there is some 

 previous debility or disease of the blood vessels. 



Symptoms and results. The symptoms are a bright vermillion 

 redness, tension or swelling, heat and tenderness. Pulsation is 

 stronger in the vessels leading into the part, secretions tend to 

 increase but may give place to a serous effusion or haemorrhage. 

 The bright redness is attributed to the rapid circulation of the 

 red globules which have not time to give iip their oxygen to the 

 tissues. It is sharply circumscribed where the affected arterioles 

 have no free anastomosis with those of neighboring parts, diffuse 

 where anastomosis is abundant, and when on the skin it is liable 

 to rise in knots or buttons as in urticaria. When pressed the 

 redness entirely disappears unlike the redness of inflammation. 



The swelling may be due to the simple turgescence of the blood- 

 vessels, but also often to transudation of serum as in and around 

 the cow's udder at parturition. The occasional migration of 

 globules, and their escape through minute lacerations in the vas- 

 cular walls add alike to color and turgescence. 



The elevated temperature (rising sometimes 3" C.) in the con- 

 gested area, is attributed to the more active circulation, and Schiff 

 prevented its appearance after section of the cervical sympathetic, 

 by tying the carotid and vertebral arteries on the same side. 



The tenderness of the congested parts varies inversely as the 

 looseness of texture and the facility for swelling. It may be 

 scarcely perceptible in the mammary region, and intense under 

 the horn or hoof. 



The functions in the congested organ are often seriously in- 

 terfered with, secretions appearing in excess or entirely altered. 

 When the congestion lasts it may cause hypertrophy, induration 

 or hyperplasia, these are however rather sequels than lesions of 

 the condition. Simple congestion- is usually quite transient, and 

 if prolonged, often merges into inflammation. 



II. Passive or Venous Congestion. In this there is no ex- 

 cess of blood entering the part, but the regular supply is delayed 

 in the veins by some obstruction, and these vessels and, later, the 

 capillaries are gorged with black blood. 



Causes, ist. Mechanical obstruction to the onward flow of 

 blood, as in the case of disease of the lungs hindering the flow of 



