Qualitative Tests 



65 



chloroform or to the presence of soda should not give cloudings which 

 would be mistaken for a full reaction with an homologous antiserum, 

 but as stated they at times obscured the delicate cloudings which in my 

 tests gave indications of blood relationships 

 between different animals, and consequently 

 if used would have vitiated the purposes 

 of my investigation. 



This leads me to a brief mention of the 

 method of preserving antisera. In the paper 

 by Nuttall and Dinkelspiel (1, vii. 1901, p. 

 378), it was stated that neither the addition 

 of chloroform, nor of trikresol to an antiserum 

 prevented the reaction taking place with 

 an homologous blood. It appeared there- 

 from that the addition of such reagents to 

 antiserum might serve a useful purpose in 

 their preservation. I however soon found 

 that there were disadvantages in adding any 

 preservative ; that it was much better to 

 either collect the serum under aseptic con- 

 ditions, or, failing this, to pass it through 

 Chamberland filters with a view to excluding 

 putrefactive organisms from it 1 . Antisera to 

 which trikresol had been added frequently 

 gave marked cloudings with non-homologous 

 bloods. Antiserum to which chloroform has 

 been added behaves in the same manner 

 unless the chloroform has been removed by 

 evaporation. In evaporating the chloroform 

 one concentrates the antiserum and alters its 

 power. I was led to use trikresol through the 

 statement by Uhlenhuth (25 April, 1901) 

 that he had obtained reactions with an anti- 

 serum preserved three months with 0'5 /o 

 carbolic acid. My experience certainly points 

 to the inadvisability of adding any preserva- 

 tive to an antiserum, for the reason that it 

 may produce pseudo-reactions, and I have no 



A. 



square 



Fig. 3. 



Test-tube containing 

 of filter-paper which 



has been soaked in saline. 



The remaining blood-dilution 



has been drawn up into the 



pipette. 



B. Antiserum contained 

 in bulb which has been sealed 

 at both ends, without the 

 serum being heated. 



C. Small test-tube such as 

 is used for testing, being figured 

 in the racks in fig. 4. 



(The figures are reduced to 

 ', natural size.) 



1 Note the effects of filtration on serum, p. 118. 



N. 



