Pernicious anaemia contrasts in many ways with chlorosis. It is not confined to the female sex, occurring as it does a little more frequently among men than among women; nor to any particular age, as it has obtained at the ages of 5 and 73, though it is most common in the third and fourth decades. Heredity, so far as is known, has but little influence, and while chlorosis scarcely interferes with the duration of life, unless from accidental complications, the tendency in pernicious anaemia is generally towards a fatal issue, though temporary rallies may prolong the patient's life for, sometimes, a period of years.

It is extremely probable that the disease is the result of an abnormal haemolysis in the portal tract. The deep colouration of the skin, urine, and stools all point to increased destruction of red blood cells, and the fact that post-mortem examination reveals the presence of iron in abnormal amount in the periphery of the hepatic lobules, indicates the special site. Changes, too, are often found in the gastro-intestinal tract. Both the stomach and the intestines may be affected. The mucous membrane is pale and perhaps shows even numerous capillary haemorrhages. It may be thinned, atrophic, or the site of fibroid changes, though these latter are uncommon; or present evidence of catarrhal processes of varying extent and intensity.

The exact character of the primary fault is, however, as yet undetermined. Dr. William Hunter is the chief advocate of the theory that pernicious anaemia is the result of a specific gastrointestinal infection. He has pointed out the general resemblance of the disease to the chronic infections, and has emphasized the frequency with which gastro-intestinal symptoms and lesions are met with. In his early papers he drew attention to the lesions that might be present in the mouth; cario-necrosis of the teeth, gingivitis, pyorrhoea alveolaris, and glossitis, often of peculiar severity and persistence; and he has isolated micro-organisms from both the gastric and the intestinal contents. The febrile paroxysms, he thinks, correspond to exacerbations of the infective process, while the intoxication is at any rate subacute during the afebrile periods.

In the present state of knowledge, the question cannot be considered as settled, as a specific organism has not as yet been isolated, or the exact site of the process determined. It may be in the stomach or bowel, or in both, or these may be simply the portal of the infection, and the actual site may be visceral.

If Dr. Hunter's theory is correct, the indications for treatment will vary during the different stages of the malady. In the quiescent periods, the main indication is the improvement of the general nutrition, the abdominal condition being more or less ignored; while during the febrile paroxysms, attention should be paid to the gastro-intestinal tract in particular, and the local irritation allayed as a preliminary step.

Our present state of ignorance concerning the bacterial processes in the bowel as a whole, even during health, entails a line of treatment which is necessarily empirical and tentative. But certain indications seem sufficiently clear, and the question must be considered from the standpoints of the bacteria themselves and the nutritive materials on which they grow.

It is evidently advisable to limit, so far as may be, the entrance of additional bacteria into the parts. It is manifestly impossible to completely sterilize the food-stuffs, and such a procedure is contra-indicated for other reasons; but care should be taken that obviously infected material (high game, dirty milk, etc.), is not ingested; and any septic focus about the mouth should be attended to, in the way already described.

If there is any evidence of gastric infection, the stomach should be washed out regularly. Antiseptic drugs, such as sul-phocarbolate of soda, carbolic acid, etc., are also of use, but the mechanical douching of the mucous membrane is much more efficacious. Herter and others have recommended similar treatment, when the symptoms point to infection of the large bowel. The former recommends the passage of the soft tube as high as is possible, and the slow introduction of fluid in quantity; and he states that he has seen notable improvement in the blood counts after such measures.

It is, of course, impossible to apply treatment of this character to the small bowel; and the results of the administration of antiseptic drugs, such as naphthol, salol, etc., are usually disappointing, even when such measures as keratin capsules and the like have been utilized. An occasional purge will of course assist, but frequent purgation will inevitably lead to defective nutrition from the loss of food material. The condition can be best attacked in other ways.

The degree of bacterial infection (that is to say the numbers of bacteria present) depends very largely upon the amount of nutritive material that is available for them. In the absence of food-stuffs, their numbers rapidly lessen. The food should, in consequence, be presented to the small intestine in such a form as will lead to its rapid digestion and absorption.

It may be urged that the lesion in pernicious anaemia is an infection of the tissues and not an intoxication derived from decomposing food. There is but little direct evidence in favour of either supposition; and even supposing that the former theory is correct, tissues freed from the continuous absorption of the products of decomposing food are surely much more likely to cope successfully with an infection than tissues exposed to such influences.