S. Okada 327 
acetic acid, the solution is made exactly one and a half times the 
volume of the blood taken. This is then shaken with kgolin (20 
gm. per 100 cc.) and immediately filtered through a folded filter. 
The first small portion of the filtrate is usually cloudy and should 
be refiltered with the same filter. When in a great hurry, it is 
recommended to centrifuge before filtration, but in this case it 
is necessary to repeat the procedure again to get clear solutions. 
The filtrate is thus quite clear, giving no turbidity or precipita- 
tion with trichloroacetic acid or with picric acid even after stand- 
ing for 24 hours, and no biuret reaction even after concentrating 
as far as possible. An aliquot part (30 to 60 cc.) of the filtrate 
is made distinctly alkaline with 1.0 N potassium hydroxide (1 to 
2 cc.), the ammonia removed by boiling 2 minutes, the solution 
made distinctly acid with acetic acid, and concentrated to the 
~ smallest possible volume; it is then transferred to a small, ac- 
curately graduated test-tube and made to definite volume (5 to 
10 cc.). The heat-kaolin method gives filtrates which rarely 
exhibit any tendency to froth, when shaken in the deaminizing 
bulb. Should frothing occur, treat again with a small portion of 
kaolin and measure the filtrate directly. Caprylic alcohol, as 
recommended for other methods, is entirely superfluous by this 
method. — 
With regard to the efficacy of the method in the recovery of 
added amino-acids, I first determined whether kaolin would absorb 
amino-acids. The following results indicate that kaolin even in 
a large amount does not absorb amino-acids at all (Table I). 
To ascertain whether the thorough manipulation described 
involves losses of amino-acids, the following experiments were 
performed. 
10 cc. of leucine solution, containing 5.42 mg. of amino nitro- 
gen were added to 33 ce. of rabbit blood, which contained 3.81 
mg. of amino nitrogen. The total amino nitrogen found was 9.07 
mg., or a recovery of 5.26 mg. of amino nitrogen from the leucine. 
Similarly, of 13.70 mg. of amino nitrogen in 10 ce. of alanine solu- 
tion, after addition to 30 cc. of blood, 13.42 mg. were recovered, 
and from 40 ce. of blood, 13.30 mg. were recovered. 10.18 mg. 
of amino nitrogen were recovered when 10.35 mg. in 10 cc. solu- 
tion of amino-acids from casein were added to 30 cc. of blood. 
Folin and Denis state that, ‘‘All reagents involving heating 
