Abstract
The studies of Ellerman and Bang, 1 Furth 2 have shown that the agent transmitting leucosis of fowls passes bacteria-tight Berkefeld filters. In most instances the bulk of the transmissible agent was easily removed from the blood by a brief centrifugalization, suggesting a relation of this agent to cells such as has been observed with some viruses. Moreover the opinion of some that the transmission of Rous sarcoma is bound to cells 3 or cell-fragments that pass silicous filters 4 has induced me to investigate the relation of the principle transmitting leucosis to cells.
When diminishing amounts of whole blood or blood cells of leucemic fowls were injected into healthy fowls leucosis was usually not produced with amounts less than about 0.0002 cc. (in terms of the original whole blood) although this quantity of blood contained from 5,000 to 50,000 leucocytes. Therefore, should transmission depend on the presence of white cells a very large number of them would be required to produce leucosis.
Undiluted plasma, after recentrifugalization for about 8 minutes at about 2000 revolutions per minute, when placed in the counting chamber appeared cell-free. Though the plasma was in all but one experiment less active than the cell suspension in producing leucosis, amounts as small as those actually contained in the counting chambers (0.002 to 0.01 cc.) were in several experiments sufficient to transmit leucosis.
No cells could be shown in Berkefeld V and N filtrates of plasma. Even a very coarse non-bacteria tight filter resisting only an air pressure of about 190 mm. appeared to retain leucocytes completely. Since most of the leucocytes can be rapidly thrown to the bottom of a tube by spinning, absence of cells in the bottom layer of such material is sufficient evidence that the entire filtrate is either cell-free or that it contains cells in small number, insufficient to transmit lesions.
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