212 Retrogressive Processes. 



puscles disintegrate and are carried off by other cells, especially 

 leucocytes, by their phagocytic action. Just as in the above-men- 

 tioned intravascular liquefaction of the blood cells, the haemoglobin 

 in its freed condition is changed into amorphous masses and 

 granules of a yellow or reddish-brown color, partly deposited in 

 the intercellular substance of the tissue and partly taken up by 

 leucocytes, endothelial and other cells. Blood extravasations may 

 also contain crystalline deposits especially in the form of rhombic 

 plates and needles of a ruby-red or yelowish-red tint, known as 

 liccmatoidiii (identical with bilirubin). This is particularly seen 

 where fluid blood remains stagnant for a long time. 



Tissues discolored bj' hssmosiderin may become slate-colored or black- 

 ened (formation of iron sulphide, pseudomelanosis) in places where they 

 come in contact with sulphuretted hydrogen (in the intestinal canal after 

 death, or in ichorous cavities and putrefying hsemorrhagic exudates). 



Icterus, Jaundice. — Staining of the tissues by biliary coloring 

 matter is known as icterus {h Urepo's) \ it occurs as the result of 

 the entrance of bile or biliary pigment into the blood und 

 fluids of the body. The common causes of such absorption of 

 bile are diseases which occasion obstruction to its passage to the 

 intestine, and therefore result in a biliary stasis (icterus from 

 stasis), and all conditions which are accompanied by obstruction 

 or narrowing of the biliary channels (obstruction from gall stones, 

 compression by tumors, swelling of the mucous lining of the 

 passages), providing the liver tissue meanwhile continues its pro- 

 duction of bile. (In hepatic diseases which lead to destruction 

 of the liver cells or to a lowered production of bile, of course 

 obstruction of the ducts cannot occasion any jaundice or only 

 minor grades of the symptom, as may be observed in distomiasis 

 of the liver, in which condition this feature is usually absent.) 

 In case the bile can no longer escape it first collects in the bile 

 capillaries. This may be observed under the microscope as an 

 engorgement of the intraacinous biliary tubes which look as if 

 actuallv injected with greenish bile substance; and the stasis may 

 be further traced into the intercellular secretory alveoli and 

 tubules. In case of rupture of these delicate capillaries the bile 

 may gain entrance into the adjoining lymph-spaces, and be car- 

 ried by way of the lymph channels into the blood (thoracic duct). 



At other times it probably escapes directly from the liver cells into 

 the blood capillaries ; it is assumed that within the liver cells, in addition 

 to the biliary secretary vacuoles, there is another canalicular system which 

 carries urea and sugar into the blood capillaries. (Nauwerk, Browicz.) 



