252 LECTURES ON IMMUNITY 



that from their observations " it must of necessity (!) be 

 concluded, that the different relations of the affinities can- 

 not give a sufficient explanation." "We must therefore," 

 they say, " make use of another factor, namely, the plu- 

 rality of the alexins and antialexins, for the explanation." 

 This conclusion shows clearly how necessary it is to be 

 cautious in regard to theoretical deductions in this disci- 

 pline of bio-chemistry. The results of similar deductions 

 led Bashf ord * to introduce one of his memoirs with the 

 words: " On immunity, especially, investigation is rendered 

 difficult by the habit of pushing conclusions farther than 

 the facts really warrant; impartial work and judgment too 

 often lead to the conviction that the ' generally accepted 

 facts ' are but flimsily supported hypotheses." 



The relations are still more complicated by the possi- 

 bility that the velocity of absorption for immune-body and 

 antialexin may be rather different in different cases. 



In two masterly memoirs Bordet 2 has considered the 

 properties of antisera, procured by injection of normal and 

 immune sera into the veins of a non-related animal. Bor- 

 det found that serum from the guinea-pigs which had been 

 treated with erythrocytes from a rabbit caused after injec- 

 tion into a rabbit, the production of substances which 

 counteracted the immune-body contained in the immune- 

 serum of guinea-pigs, as well as the alexin in normal serum 

 from guinea-pigs. This antialexic action not only protected 

 the erythrocytes of rabbit, treated with the said immune- 

 serum, from being haemolysed, but even cholera vibrios, 



1 Bashford: Journ. of Pathology and Bacteriology, 8. 52 (1902). 



2 Bordet : Ann. de VInst. Pasteur , 18. 593 (1904) ; Bordet and Gay : ibidem, 

 20. 467 (1906). 



