Till; PRECIPITIN REACTION. 



tions have been made on both rabbit and chicken antisera before 

 and after filtration. The results are shown in Table VII. 



The results given in Table VII. are typical of them all with 

 the exception of a single chicken antiserum which apparently 

 lost some of its antibodies on filtration. Small Mandler filters 



TABLE VII. 



THE EFFECT OF FILTRATION ON TITER. 



have been used for this filtration. In general there has been no 

 loss of titer. In fact the titer usually increases after filtration 

 due to the increased clarity of the antiserum and the consequent 

 greater ease of detecting a fine ring in the last tube. Insofar as 

 the effect on specificity has passed beyond the range of error it 

 has been in the direction of a lesser specificity and would thus 

 tend to neutralize the effect of using 2.25 per cent, salt solutions 

 in the chicken antisera. 



RESULTS ON RELATIONSHIPS. 



The experimental results bearing on matters of technique have 

 all been secondary to the main problem of this investigation, 

 viz., the application of the precipitin reaction to the study of 

 of the relationships of certain animals. In the tables and figures 

 recording the data obtained in the study of relationships the 



