CAUSATION. 225 



of vessels, these changes being accompanied with fever and 

 specific lesions in internal visceral organs. Independent of 

 this origin of pycemia or septica3mia, by introduction of an 

 infective agent from without, it seems that similar results may 

 follow from peculiar inflammatory changes in the tissues of 

 animals themselves. We know that micrococci and bacterial 

 forms are usually to be found in the tissues of even healthy 

 animals. 



h. Caused ion. — The immediate cause of pyaemia is to be looked 

 for in the existence of some diseased part or tissue which so 

 operates and influences the blood passing through it, either by 

 addition to it of some active and distinct entity, or through an 

 alteration of its already existing elements, that it is prone to 

 induce disturbance, change, and suppuration in distant situa- 

 tions to which it may travel. These situations are usually in 

 the capillaries of the lungs, the liver, the kidneys, and also in 

 other parts of the body more superficial. In those cases which 

 foUow suddenly after the occurrence of extensive wounds or 

 operative interference, chiefly in situations where there is 

 difficulty of obtaining a free exit to purulent matter, or where, 

 from other conditions, such is unduly retained, there are few or 

 no local lesions, and death is brought about by excessive blood- 

 contamination. 



In those instances which occupy longer time in the perfect- 

 ing of the process, and where the poison, after its introduction, 

 is augmented by self-multiplication, and where distant local 

 suppurative changes are conspicuous — true pyaemia — we will 

 usually find that such is sequent to suppurative action in some 

 part, often to necrosis of bone-tissue. Another point of which 

 we are tolerably certain is, that inflammatory action and pus- 

 formation, in their capacities to induce pysemia, are not always 

 alike, but are modified by the type of the action, the tissues 

 affected, and the conditions with which the animals are 

 surrounded. 



To understand pyemia completely Dr. Sanderson, in dealing 

 with experiments relating to it, states, we ought to consider its 

 origin, its symptoms, and its anatomical characters. In defin- 

 ing it he says : 



' 1. Pyaemia originates by the introduction into the blood of 

 a poison which is itself the result of the inflammatory action. 



15 



