fit Individual Sera 145 



moderate 



weak 



Measurements of -002 to '001 can still be made. Weaker antisera than that for the 

 Keindeer were not used or standardized. 



On Differences in the Reactions of Individual Sera belonging 

 to the same Species of Animal. 



In the investigations which I have made I have not studied the 

 question of individual differences in the reaction of normal sera to their 

 homologous precipitins. Together with Mr Strangeways, I have made 

 a number of measurements on normal sheep sera with anti-sheep serum, 

 and have obtained remarkably uniform results by means of my quanti- 

 tative method. These results will be published later. On the other 

 hand Mr Strangeways has observed a considerable amount of variation 

 especially in human subjects affected with various diseases. It is not 

 impossible that disease has in some cases been the cause of my obtaining 

 greater reactions than would be expected according to theory. I shall not 

 at present lay stress upon this point, but shall only, as an example, draw 

 attention to the very great reactions I obtained with two Cercopithecus 

 bloods (see Section VI) when testing with anti-human serum. Linossier 

 and Lemoine (8, in. 1902) were unable to observe any individual differ- 

 ences in two human sera, the one being obtained from a case of pneumonia, 

 the other from a case of uraemia. One of these sera had been used for 

 the treatment of the rabbit which yielded the antiserum. 



That there may be individual differences in health is indicated by 

 the investigation of Moro(31, x. 1901) on lactosera (see p. 159), who found 

 that different women's milks reacted especially to the antisera to which 

 they had given rise. His results will however require confirmation. On 

 the other hand we have evidence of differences between maternal and 

 foetal blood in this respect 1 . Thus Halban and Landsteiner (25, in. 1902, 



1 Halban and Landsteiner (p. 473) cite Kriiger (1886) as having found foetal blood to 

 contain more solids but less fibrin than maternal blood. Scherenziss (1888) found the 

 sneeiBc gravity of foetal markedly lower than that of maternal blood, although it con- 



H. 10 



