374 



MARSHALL AND TEAGUE. 



serum gave precipitation with normal salt and with all mammalian 

 serums, though not with chicken and duck serum; another serum, an 

 anti-Malay (Filipino) serum, gave some reaction with the serum of a 

 rat; otherwise all of the antiserums were specific as is shown in the 

 following table : 



Table VII. — Precipitin reactions. 



Dilution of serum 

 from— 



Serum of 

 anti-Cau- 

 casian 

 rabbit 

 No. 3168. 



Serum of 

 anti-Fili- 

 pino rab- 

 bit No. 

 3167. 



Serum of 



anti- 

 monkey 

 rabbit 

 No. 3195. 



Serum of 

 anticara- 

 bao rab- 

 bit No. 

 3008. 



Serum of 



anti- 

 chicken 

 rabbit 

 No. 1214. 



Caucasian 



+ 

 + 

 + 

 

 

 

 

 

 



+ 

 + 





 

 

 

 



+ 

 + 

 + 

 

 

 

 

 

 



+ 

 + 











+ 





 

 

 



+ 

 

 

 



Monkey 



Chicken _ 



Dog 







Pieces of filter paper were moistened with a drop or two each of 

 various serums and were allowed to dry and remain at room temperature 

 for from one to three months. They were then extracted with distilled 

 water and an equal volume of 1.7 per cent salt solution was added to 

 each preparation. These extracts were tested against each of the varieties 

 of precipitin serum and it proved easy to differentiate the albumens 

 in this way. By using an anti-Caucasian and antimonkey serum with 

 varying dilutions of the extracts it was not difficult to distinguish even 

 between monkey and human serum. 



The precipitin technique used throughout the experiments was the 

 ring method. A drop of undiluted antiserum was placed in a small tube 

 of from 3 millimeters to 6 millimeters in diameter; upon this a dilution 

 of test material was placed with care to preserve the line of contact 

 between the two fluids. A precipitin reaction became evident very 

 quickly in a ring of precipitum at the junction of the two fluids, exactly 

 resembling the albumen ring in the nitric acid test for albuminous urine. 

 It was found that most accurate readings could be made in from 15 

 minutes to about one hour, the reaction being less distinct after mixing 

 of the two fluids occurs. 



The technique of the deflection method has already been discussed at 

 length. 



A specimen of Caucasian blood was obtained from an American and 

 specimens of blood were also obtained from a Negro, Chinese, Japanese, 

 Xegrito, Tagalog and monkey. Dilutions of these serums were prepared 



