374 THE BLOOD AND THE BLOOD- FORMING ORGANS. 



A persistent diminution in the number of red cells may be effected 

 either by ^mcrrafflftd destruction (hwrnatolysis) or by defective formation 

 (lunHtttoycHcxix) of these elements, but the relation of the two factors in 

 the production of the chronic amemias is as yet imperfectly determined. 



Jj^XJEESlVE H^MATOLYsis occurs after burns, is the result of 

 poisoning by arsenic, phosphorus, and chlorates, phenylhydra/in, 

 uitrobenzol, acetanilid, etc., and may occur in infectious diseases 

 through the action of bacterial toxins. All stages of a peculiar de- 

 struction of red blood cells may readily be followed in the blood in 

 malaria. In chronic infectious diseases, prolonged suppuration, and in 

 the cachexia attending malignant new growths, destruction of red cells 

 is probably effected, in part, by toxic agents circulating in the blood. 

 In pernicious anaemia the condition of the blood may, with considerable 

 certainty, be referred largely to a destruction of red cells by some un- 

 identified toxic material in the blood. 



In the process of destruction of the red cells, especially if rapid, 

 haemoglobin may be separated from the cells, dissolved in the plasma 

 (ha3moglobina3inia), and may then be excreted unchanged in the urine 

 (hsemoglobinuria). 



The gradual and more common form of destruction of red cells is 

 attended with an alteration of the haemoglobin, effected chiefly in the 

 liver, and with its deposit in the eudothelial and glandular cells of vari- 

 ous organs, especially in the _liyer, spleen, kidneys, Mnf TnflTTfrTrr nnrl 

 secondarily in apy of the_tissiies^ 



A~part of the altered haemoglobin is to be found, in the form ofpig; 

 meiit granules, or as a diffuse deposit, in the cells of the above-named 

 organs, where its content of iron may or may not be demonstrable by 

 microchemical tests (hcemosiderin). Another product of the haemoglo- 

 bin, not containing iron, may be found in the same situations, in the 

 forms of granules or crystals (hcematoidin). Finally, the derivatives of 

 haemoglobin are excreted largely in the form of normal or pathological 

 urinary pigment. The remaining fragments and stroma of the red cells 

 are soon removed from the circulation largely by leucocytes, and partly 

 by endothelial cells and giant cells, in the liver, spleen, and marrow. 



DEFECTIVE^ H^MA^TOGF.TV^STS must be regarded as a cause of such an- 

 emias as are associated with pathological changes in the bone marrow 

 (pernicious anemia), and in the lymph-nodes, spleen, and liver (leukae- 

 mia). This too is probably the chief cause of the anaemia following 

 prolonged malnutrition (secondary anaemia). The pathological changes 

 in the blood-producing organs may sometimes arise as primary diseases 

 of these organs, or similar changes may be secondary to excessive de- 

 mands for the regeneration of the blood. In mild grades of anaemia the 

 regeneration of the blood is attended with an hyperplasia of the red 

 marrow, which replaces the yellow marrow of the long bones. The chief 

 defect in the production of red cells may then be a deficiency in haemo- 

 globin (chlorosis). In severe and prolonged anaemia, under the influ- 



