DISEASES OF BLOOD AND BONE MARROW 109 
processes, but an analogous contrast may be found in the 
pathologic anatomy of acute and chronic leucemia in man, 
and I am inclined to view them as stages of the same dis- 
ease. In one of our infectious cases noted above the lesion 
was certainly myelogenic for the infiltrate in the organs 
and the cells in blood smears showed an enormous number 
of eosinophilic and basophilic polynuclears greatly in 
excess of normal. The study of two of our cases confirms 
the picture as given for lymphatic and myeloic leucosis 
by Ellermann (1), but material corresponding to his 
lymphoidocytes or erythroleucotic group has not come to 
our attention. Cells with deeply staining basophilic 
protoplasm and a lymphoid nucleus are certainly to be 
found with reasonable ease in the avian marrow normally 
and, more than this, can be detected by careful search in 
nearly all cellular infiltrates of organs not leucemic in 
nature. Perhaps, as Ellermann states, they are collateral 
stages in normal erythrogenesis. 
The Bone Mareow. 
Since the foregoing conditions so vitally concern the 
bone marrow, it is but natural to give to this structure 
a separate consideration. From what is known of the 
origin, physiology, anatomy and regeneration of the 
marrow from the work of Ponfick, of Neusser, Bunting, 
Selling, Werigo and many others, it seems highly 
probable that the principal conclusions reached in the 
study of human medicine and experimental pathology, 
apply to the whole group of animals here under discus- 
sion. The peculiar arrangement already mentioned as 
encountered in the marrow of birds differs little if any 
from the erythropoietic centres seen in man after experi- 
mental anemia, although it may be somewhat more 
orderly. Myeloblasts or megakaiyocytes are not numer- 
ously present in any order, but seem more prominent in 
the mammals than in birds. In so far as the mononuclear 
( 1 ) The Leucoses of Fowls, London, 1922. 
