CHANGES IN THE COMPOSITION OF THE BLOOD. 71 
Of what are emboli composed ? 
Emboli are formed most often from detached bits of thrombi. They 
may be formed of fragments of: heart valves, tumors, masses of bac- 
teria, drops of fat from marrow of fractured bones, bubbles of air, etc. 
If an embolus lodges in a terminal artery what occurs ? 
The affected region usually dies; there may be an extravasation of 
blood by diapedesis (hemorrhagic infarction), or the part is deprived of 
blood and nourishment and undergoes necrosis. The seat of trouble 
is light in color and is called a white infarction. 
What is lymphorrhagia ? 
It is the condition occurring when a lymphatic vessel is ruptured 
and the contained lymph is effused into the surrounding tissue. 
CHANGES IN THH COMPOSITION OF THE BLOOD. 
Define the conditions hydremia and anhydremia. 
Hydremia is a condition in which the watery constituent of the 
blood is increased above the normal. Anhydreemia is directly opposite, 
the watery constituent is less than the normal amount. 
What are the changes in blood in leucocytosis and leukemia or leu- 
cocythemia ? 
In the former there is simply a temporary increase in the number of 
white-blood cells, while in the latter there is a persistent, progressive, 
aud enormous increase of the white-blood cells. 
What are the changes in the blood in anemia ? 
The red-blood cells may be diminished in number or deficient in 
hemoglobin, or both conditions may be present. In pernicious anzemia 
numbers of spheroidal or irregular-shaped bodies are found, supposed to 
be distorted red-blood cells. These are called microcytes. 
Describe melanemia. 
Tn this condition the blood contains irregular particles of black or 
brown pigment, sometimes free, at other times enclosed in the white- 
blood cells. 
Name some of the foreign bodies found in the circulating blood. 
Air, degenerated epithelial cells from vessel-walls, tumor cells, frag- 
ments of decomposing thrombi, bits of heart valves, fat (normally 
present in digestion and lactation), parasites, and bacteria. 
