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the haemoglobin. The isotonic point of human blood 
is about o'qi per cent, salt solution. 
To Determine the Isotonic Point 
1. Measure out one c.c. of each salt solution 
of descending strengths, 0*43 per cent., 0*41 per cent., 
0*39 per cent., etc., into four small test tubes and 
one c.c. of water into a fifth tube. 
2. Add to each the amount of blood (or the blood 
may be washed free from serum by centrifugalizing 
and used as an emulsion of known strength in salt 
solution) contained in two divisions of the stem of a 
Thoma-Zeiss pipette (the whole stem contains ten 
divisions). 
3. Allow to stand for some time. Some of the 
solutions will have haemoglobin in solution. 
In malaria, the resistance of the blood is lowered, 
thus, whereas in a control normal blood a 0*41 per cent, 
salt solution gave no haemolysis ; in the case of two 
malaria patients, the haemolysis was well marked. 
In blackwater fever, on the contrary, a raised 
resistance of the blood may be found. 
The Urine 
It is especially in blackwater that we still require 
complete analyses of the urine, and more especially 
in those who are constantly subject to malarial attacks 
and are at the same time taking quinine. It is possible 
that such analyses might give us indications which 
would enable us to avert the danger of an attack of 
blackwater fever and to determine when quinine should 
not be given. 
Albuminuria .—The occurrence of albuminuria in 
malaria varies according to the particular country ; 
Q 
