170 CHAPIER IS. 



These products, though of very different kinds, are all derived from 

 the blood. They are, first, serum or the watery part of the blood; 

 secondly, albuminous fluid; thirdly, coagulable lymph; fourthly, the 

 blood itself. The swelling may be hard or may pit on pressure, accord- 

 ing to varying circumstances. 



Swelling of the part necessarily accompanies every attack of iiiflam- 

 mation, but the amount may be so small as to be scarcely appreciable. 

 This apparent absence of swelling is particularly noticeable in bones and 

 other firm substances. 



346. Throhhing. 



Throbbing of the arteries is caused by a sort of regurgitation of the 

 blood, which is partially airested in its onward course by the congested 

 state 'of the vessels at the seat of the disease. It is a marked sign of 

 inflammation. 



Thi-obbing is useful in many cases in enabling us to determine with 

 more certainty than we otherwise could the real seat of the disease. 

 For example, inflammation in the interior of the foot is plainly indicated 

 by throbbing of the plantar arteries. 



347. Constitutional symptoms. 



Inflammation, when tolerably severe or extensive, tells of its existence 

 by other signs besides the local symptoms already detailed. It soon 

 causes constitutional disturbance, which is recognised by shivering, cold 

 extremities, dryness of the mouth and nostrils, constipation of the 

 bowels, and diminished action of the skin and kidneys. 



When the disease is complicated with or aggi-avated by fever, as in 

 such cases it usually is, it will be marked by fm^ther symptoms, namely, 

 an accelerated pulse, quickened breathing, and irregular temperature of 

 the part at different times. 



Though in its origin the disease is always local, yet in some cases the 

 constitu'tional disturbance may precede the visible manifestation of the 

 local symptoms. 



348. Shivering. 



Shivering is a symptom of the greatest importance. It is generally 

 present in the early stages of all serious attacks of inflammation. It 

 often indicates some important change in the character of the blood, or 

 is due to altered condition of the nervous system, or to the shock of an 

 impending disease. No case in which Shivering is present should be 

 ever neglected for an instant. Although the animal may be shivering, 

 the skin may be hot and burning. 



349. Symptoms indicative of the loraUly of the part attacked. 

 The symptoms vary very much according to the part attacked. In all 

 serious cases, such as inflammation of the brain, eyes, feet, lungs, or 



