182 
MALARIA 
positive sera became negative after expo¬ 
sure to heating to 55° C for 30 minutes, 
indicate that the reaction does not have an 
antibody basis. On the other hand, several 
observers have noted a parallelism between 
the melano-reaction and a flocculation in 
mixtures of serum and distilled water. 
Observations by Chorine and Gillier (1934) 
indicated that the substance flocculating in 
distilled water is water-insoluble euglob- 
ulin, probably associated with other sub¬ 
stances such as cholesterol, lecithin and 
uric acid of low water solubility. It thus 
finally appears that the reaction of Henry 
is due to a disequilibrium of serum pro¬ 
teins brought about by an increase in 
serum globulin, in which the melanin served 
as an indicator. 
Based on these principles, Proske and 
Watson (1939) report a simple colometric 
test to detect an increase in euglobulin, 
which avoids the need for an expensive 
photometer required for the original Henry 
test. “The procedure is based on the fact 
that proteins possess a chromogenic prop¬ 
erty which can be measured quantitatively 
against the color produced by pure tyrosine 
in the presence of a phenol reagent. This 
chromogenic value is constant for a given 
protein and the intensity of the color pro¬ 
duced can be used as a measure of the 
amount of the protein examined. Serum 
euglobulin is precipitated from the serum 
to be examined by the addition of 13.5 per 
cent sodium sulphate solution, according to 
the method of Howe. The tyrosine chromo¬ 
genic index (TI) is determined by compari¬ 
son with standards prepared from pure 
tyrosine (Pfanstiehl).” 
“The tyrosine index for euglobulin fluc¬ 
tuates between 50 and 80, while that for 
serum from malaria patients ranges from 
80 to 280, or higher. The test was found to 
be indicative of the presence of malaria in 
97.4 per cent of known cases of malaria 
examined, as compared with 81.9 per cent 
positive thick blood films examined at the 
same time.” 
