368 



MARSHALL AND TEAGUE. 



Table VI. — Comparison between fresh pig's serum and pig's Hood dried on linen 

 about three months. 



Pig's serum, or pig's blood spot. 



Anti- 

 pig 



Guinea- 

 pig com- 

 plement. 



Anti- 

 sheep 

 serum. 



Sheep 

 cor- 

 puscles, 

 5 per 

 cent. 



0.1 



.002 



5 



0.1 



.002 



5 



0.1 



.002 



5 



0.1 



.002 



5 



0.1 



.002 



5 



0.1 



.002 



5 



0.1 



.oo3 



5 



0.1 



.002 



5 



0.1 



.002 



5 



0.1 



.002 



5 



Serum . 01 .__ 

 Serum . 001 .. 

 Serum . 0001 _ 

 Extract .01— 

 Extract .001. 

 Extract .0001 

 Serum .01... 

 Extract .01.. 



Lysis. 



Lysis. 

 Complete. 

 Complete. 

 Complete. 

 Complete. 



Neisser and Sachs (13) and Schiitze (14) call attention to the fact that the very 

 sensitiveness of the test lays it open to error, and in testing for the specificity of 

 a drop of blood on a piece of cloth, error may arise from the fact that the cloth 

 may be contaminated by sweat or nasal secretion, or some other organic body 

 substance. They therefore use as one control a test made with extracts from 

 the cloth adjacent to the blood clot but free from blood. 



Neisser and Sachs also used a control with boiled extract, as boiling removes 

 the specific action of the serum deflection. 



All tests in which there is evidence of bacterial action must be discarded (14). 



Schiitze(l4) (Table VI) dried pig's blood on linen for three months and made 

 a comparative test of this material with fresh pig serum with the deflection 

 technique. One drop dried on a piece of cloth about 2 cubic centimeters in 

 diameter dissolved in 2 cubic centimeters of salt solution and the extract cleared 

 and filtered, had a deflecting strength of 0.01, while the fresh serum had a 

 deflecting strength of 0.0001, the reaction being specific. 



It is seen that there is an abundance of experiments which prove that when 

 carefully performed, the deflection test is just as reliable as the precipitin test 

 in differentiating between blood from different species, and that Neisser and 

 Sachs, Schiitze and Bruck, have found it possible to use it where the precipitin 

 test is not available. 



Neisser and Sachs recommend the adoption of the deflection test in forensic 

 procedure, as a supplement to the precipitin reaction. They point out that it 

 has certain advantages over the precipitin test which are: That it acts as a 

 control for the precipitin method; that haemolysis is a much more definite index 

 than minute precipitation; that an opalescent serum is available for use; that 

 it is not necessary to" have such high potency serum as is needed in the precipitin 

 test and that it is not necessary to wait for the clearing of the serum, which is 

 so tedious in the older test. 



They recommend in every forensic case in which the diagnosis of blood must 

 be undertaken that the precipitin test be performed and upon its completion 

 fresh guinea-pig serum (1.0 cubic centimeter of 1 : 10 dilution) be added to 

 each tube and the same materials be employed in making a deflection test. 



Schiitze agrees with Neisser and Sachs as to the value of the deflection test, 

 while Bruck goes a step further. He recommends that the precipitin test be 

 followed by a deflection test in which moderately strong immune serum is em- 



