78 HISTOLOG I ' OF NUTRIENT PL UIDS. 



washed into the general circulation, or detached portions of 

 diseased valves, etc., may be carried into the blood and pro- 

 duce embolism in the arteries, capillaries, or some branch of 

 the portal vein. This is invariably followed by partial or com- 

 plete suspension of function in the part thus deprived of nutri- 

 tion. 



Mechanical thrombi and emboli do not necessarily produce 

 pyaemia or septicaemia, only as they become foci for septic 

 poison. They may be organized into new connective tissue in 

 the place where they lie, or fatty degeneration may begin in 

 the center and form a pap-like mass, ending in lactification and 

 absorption. 



2. Altered haemoglobin. Haemoglobin readily unites with 

 various gases. With oxygen it forms oxyhaemoglobin and 

 gives the bright red color of arterial blood. With a small 

 proportion of carbon dioxide it produces the dark red color 

 of venous blood, and with a larger amount, as in death from 

 suffocation, a nearly black color. Combined with carbon ox- 

 ide, as in inhalation of burning charcoal fumes, and some 

 kinds of illuminating gas, the blood becomes a bright cherry 

 red and there is absence of post-mortem coagulation. 



Diminution of haemoglobin, as in leucaemia, produces a pale 

 red blood. Sometimes, after severe burns and certain poisons, 

 as well as in septicaemia, the haemoglobin is dissolved out of 

 the red corpuscles and is held in solution by the serum. This 

 state is known as Jiceinoglobincenda, When it produces a flow 

 of nearly black urine it is hcemoglobinuria. 



4. Presence of abnormal elements. 



i. Melancemia. After severe or long continued malarial in- 

 termittents, the blood may contain granules of black, brown, 

 or yellow pigment, probably the result of destroyed red glob- 

 ules. The granules may be free in the plasma, or inclosed in 

 round or spindle-shaped cells of various sizes. Some of these 

 cells have amaeboid motion. Occasionally they appear cylin- 

 drical, and more or less fractured. Melanaemia is generally 

 accompanied by decrease of red corpuscles (oligocythaemia) 

 and temporary increase of white globules (leucocytosis). 



