In studying yellow fever in experimentally infected Macacus rhesus it is most desirable to have something more than the temperature curve, appetite, and general appearance of the monkeys, upon which to base a working diagnosis and a prognosis of the disease. Recently we investigated the value, for this purpose, of the icterus index of Muelengracht and the bromsulphalein liver function test of Rosenthal and White, making about 600 determinations of each upon 114 rhesus monkeys, largely in the course of other experimental work.
The icterus index was determined according to the technic of Murphy (1), but it was found necessary to modify the technic of the bromsulphalein test from that described by Rosenthal and White (2). Intramuscular injection of the dye was substituted for intravenous injection, and a dose of 5 mgm. per kilogram of body weight was used instead of the usual 2 mgm. per kilogram. Blood was withdrawn only once, at the end of one hour, from the heart, using an eighten-gauge needle and as little suction as possible, to avoid hemolysis.