178 



Tests with Precipitins 



Eeactions 



It is owing doubtless to a slight cloudiness and also to the feebleness 

 of this antiserum that the results tabulated above appear at first sight 

 less in accord with the preceding. It is obvious that it is more 

 difficult to estimate different degrees of reaction when at most moderate 

 cloudings occur and the precipitum observed after 24 hours is so small 

 in quantity. It is evident nevertheless that the bloods of the Pinni- 

 pedia react more than do the others, numerically if not apparently 

 quantitatively, and it would appear also that there is a preponderance 

 of reactions amongst the other Carnivora. It is notable again that the 

 Primates stand out amongst the other mammalia, in a manner corre- 

 sponding (but less marked) to what has been stated with regard to the 

 preceding three antisera for Carnivora. 



IV. Antisera for Bloods of Rodents. 



Antisera for rabbit blood have been obtained by only a few observers, 

 the first of these being Nolf (v. 1900) who produced it by treating 

 a fowl with rabbit serum. Bordet (ill. 1899) failed to find any precipitin 

 in guinea-pigs treated with rabbit serum, whereas Gengou (25, x. 1902, 

 p. 743) claims that the serum of such guinea-pigs produced a " distinct 

 opalescence" in rabbit serum dilutions, although it did not produce 



