366 MARSHALL AND TEAGUE. 



In testing blood stains in their three forensic cases, they(12) made extracts of 

 the stain with normal salt solution using very small amounts of the solution. 



The work of Neisser and Sachs has been repeated and its value tested by 

 Sehiitze(l4), by Bruck(15, 16, 17) and by Bauer(l8). 



The antisheep serum used by Schiitze(l'l) is of such a strength that 0.0005 to 

 0.00033 cubic centimeter dissolves 3 cubic, centimeters of 5 per cent suspension of 

 sheep's corpuscles when treated with 0.1 cubic centimeter of fresh guinea-pig 

 serum. He (14) immunizes rabbits either by intravenous inoculation of 3 cubic 

 centimeters of human blood repeated three times or by subcutaneous inoculation 

 of 8 or 10 cubic centimeters repeated five times. One week after the last inocula- 

 tion the blood is drawn from the animal, the serum placed upon ice to clear, 

 after which it is centrifugated and inactivated for one-half hour at 55°. 



He makes his various dilutions in such a manner that the required amount of 

 each constituent is contained in the volume of 1 cubic centimeter, the total of 

 volume in each test tube being brought up to 5 cubic centimeters with salt 

 solution. 



Bruck(l6) immunized rabbits by intravenous inoculations of 2 to 3 cubic 

 centimeters of serum repeated after eight day intervals and the blood was drawn 

 a week later. Of this serum 0.1 cubic centimeter usually precipitated the 

 homologous antigen in a dilution of 0.1 or 0.05. With such a serum he could 

 differentiate between the blood of the European, Chinaman, Arabian, Malay and 

 monkey, by definite quantitative differences obtained in the reaction. 



In differentiating between the serums of various human races two inoculations 

 of the rabbits gave such a strength that using 0.1 of the serum with 0.1 of com- 

 plement, deflection was obtained with 0.001 of the tested serum. Stronger serums 

 gave doubtful results. Bruck emphasizes particularly the importance of using 

 small doses for inoculating and immunizing the rabbits, so that only very low im- 

 munity is obtained. Acting upon this idea in a subsequent series of experiments, 

 Bruck(l6) immunized rabbits with 0.5 cubic centimeter every five days, giving 

 three doses intravenously and ten days after the last dose withdrew the serum from 

 the animal and tested it for its deflecting power. With this serum he could 

 differentiate blood, pus and semen, from the same individual, using monkeys for 

 obtaining the antigen for inoculation. In this test he used 0.1 of guinea-pig 

 serum, 0.1 cubic centimeter of sheep's corpuscles plus two dissolving doses of 

 hemolytic serum, 0.1 cubic centimeter of antigen and a weak immune serum in 

 dilutions varying from one-twenty-fifth to one-four hundredth. 



The controls which are used vary according to the purposes for which the test 

 is performed. 



The general plan of the experiments of Neisser and Sachs, Bruck and Schiitze 

 with the controls and results are shown in the appended tables. 



The following table, No. IV, of Neisser and Sachs (11) shows that the deflection 

 is produced by human serum and that the reaction is specific, being given by no 

 other serum except slightly by that of monkeys. 



0.1 cubic centimeter of antihuman-rabbit serum+0.05 cubic centimeter guinea 

 pig-serum+varying amounts of various normal serums as possible antigens+ 

 normal salt solution up to 1 cubic centimeter are brought together. After stand- 



