386 THE BLOOD AND THE BLOOD-FORMING ORGANS. 



SECONDARY ANAEMIA. 



\Vhile chlorosis may be considered usually a disease of adolescence, 

 and while its occurrence is almost wholly confined to the female sex, 

 there is another type of blood change which seems best classified under 

 the heading of (secondary auaemiaXand which is independent of sex or 

 age. The determining agents are either of a general nature, such as poor 

 food and bad air, or they are actual diseases, or they may be intestinal 

 parasites, or finally chronic poisoning. Among those diseases which are 

 likely to induce a well-defined anaemia we may mention prolonged sup : 

 ] >u ration, diseases of the stomach and intestines, malaria, syphilis, and 

 malignant tumors. The intestinal parasites are chiefly the Ankylostonia 

 duodenale and the Bothriocephalus latus. The poisons ,are lead, and, 

 more rarely^arseuic. The alterations which are apparent on examining 

 thelSIbod are very variable, depending upon the agent. The haemoglobin 

 is^regularly diminished to a greater per cent than the red cells ; it may 

 fall as low as l.Vi'o per cent ; the red cells rarely fall below one million. 

 Nucleated red cells of the normoblastic type are frequent in the severe 

 cases ; megaloblasts are not found except in the most advanced cases, and 

 then in small numbers. As a rule the average diameter of the red cells 

 is slightly below normal, with a moderate poikilocytosis. Granular de- 

 generation is present to a variable extent in the red cells except in malaria 

 and lead poisoning, when it is the rule. In the anaemias produced by 

 the intestinal worms the blood picture may be that of pernicious anaemia, 

 with a great increase in the size of the cells and the appearance in the 

 blood of numerous megaloblasts, thus forming an exception to the general 

 rule that the blood of secondary anaemia is normoblastic in type. The 

 leucocytes are increased, as a rule, in cases due to suppuration and to 

 tumors ; in other forms there is usually but little change in the number, 

 though it is impossible to formulate a general rule (Plate II., Fig. 3). 



PERNICIOUS ANJEMIA. 



Pernicious anaemia is a disease of the blood and blood-forming organs, 

 characterized by excessive destruction associated with defective produc- 

 tion of red cells. 



The exact relation of the factors concerned in the causation of the 

 disease has not been determined. It may be said, however, that while 

 very rapid cases of pernicious anaemia have been observed unaccom- 

 panied by the usual lesions in the bone marrow associated with defective 

 haematogeuesis, the disease seems not to exist without excessive haernato- 

 lysis. 



Pernicious ana'inia may probably originate as a primary disease of 

 the blood or bone marrow, but many cases apparently primary have 

 been shown at autopsy to be secondary to such conditions as cancfij^ 

 nephritis, tuberculosis, atrophy of the gastric mucosa, or the presence of 



