Abstract
In certain diseases it is believed that the symptoms are due to a toxin which circulates in appreciable amounts in the blood stream. Efforts have been made to demonstrate this substance in the blood of diseased men and animals by chemical analysis, or by the injection of their whole blood, blood serum or blood extracts into healthy animals. These injections have been given intravenously or intraperitoneally. It was believed that if the individual was poisoned by such a toxin, the injection of his blood or blood serum into healthy animals would produce toxic symptoms in them. The negative results in these experiments have been considered proof of the absence of such an intoxication.
It seemed to us, however, that toxic substances might be so rapidly removed from or inactivated in the blood that although an individual was suffering from a profound poisoning, the substance might not be demonstrable in the blood stream.
The following experiment was devised to test this assumption. Dogs were matched as for size and the compatibility of their bloods and were anesthetized with sodium barbital intravenously (200 to 250 mg. per kg.) or by stomach tube (250 to 300 mg. per kg.). They were then prepared for the typical carotid-artery-jugular vein crossing of circulations. In addition the transfer of blood was recorded and kept equal by means of the Montgomery and Lipscomb volume flow apparatus. 1 Heparin (30 mg. per kg.) was used as an anticoagulant and the blood pressure was taken from the femoral artery. The dogs were labeled A and B. The drug to be tested was injected into the femoral vein of dog A and was allowed to circulate for varying intervals of time, after which the 2 circulations were crossed. Dog B was observed for changes characteristic of the drug.
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