Abstract
The difference between haemopathies (which originate in the blood-forming tissues) and blood-diseases (which develop in the blood-stream) is explained and illustrated by examples and specimens.Primary anaemia caused by the hyperplasia of the erythroblastic tissues in the marrow occurs in fowls as erythromyelosis. This condition can be experimentally transmitted, though inoculation in fowls may reproduce the anaemic disease, or give rise to a persistent polyerythrocythaemia. On farms erythromyelosis is often, but not always, associated with the cestode, Davainea proglottina.Secondary anaemia develops in splenectomized rats following the invasion of the erythrocytes by Bartonella muris. The subsequent erythrocytolysis may induce haemoglobinuria, similar to that occurring in man and cattle as the result of certain haemic infections.Oligoerythrocythaemia is frequently seen in fowls associated with leucocythaemia; the deficiency of the red blood-corpuscles is due to the pressure on the erythroblastic sinusoids, by the proliferation of the myeloblastic or lymphoblastic tissues in the marrow.Lymphocythaemia (and lymphomatosis) have been observed in canaries, fowls, mice and guinea-pigs. The conditions can be experimentally transmitted within the species; inoculation with lymphocythaemic blood may reproduce the haemic type or induce the development of scattered tumour-like deposits (lymphomatosis). Whichever type of lesion results, the pathological cell unit is one of the lymphoblast-lymphocyte series.Fowl leucocythaemia originates through the morbid proliferation and premature entry into the circulation of cells of the myeloblast-granulocyte series. On inoculation in fowls the original leucocythaemia may be reproduced; rarely there follows the development of localized deposits of myeloblastic cells in the skin.As these diseases of the blood-forming system, and those occurring in man and cattle offer many striking resemblances, it may be suggested that the determination of the origin of the particular type of cell encountered should serve as guide to diagnosis and classification in all haemopathies.