xix. THE BLOOD OF THE PASCHAL LAMB. 333 



undertaken with some reasonable prospect of suc- 

 cess. 



In conducting experiments that have yielded such 

 satisfactory results to the scientific theorist and the 

 practical physician who has to fight against disease, all 

 kinds of substances have been used in all possible con- 

 ditions. One experiment is of special interest in con- 

 nection with our present subject. Infusions of various 

 materials carrots, apples, and leaves of various plants 

 have been made, and placed in bent and rounded 

 tubes, through which atmospheric air, that had been 

 made to pass over pieces of pumice-stone steeped in 

 fresh blood or in a solution of gelatine or sugar, was 

 forcibly drawn by a special pump. It was invariably 

 found that the infusion which had received into it the air 

 that had passed over the blood, continued longer fresh 

 and sweet than the infusions which had received their 

 air through the sugar or gelatine. The fresh blood 

 seems to have attracted the germs that were floating up 

 and down in the air of the room more powerfully than 

 the gum or the sugar, in spite of their adhesive proper- 

 ties, and thus prevented these germs more effectually 

 from reaching the infusions in the glass tubes and 

 setting up a process of putrefaction in them. The con- 

 clusion from this experiment was irresistible that fresh 

 blood has a peculiar attraction for germs floating in the 

 atmosphere, which cannot be accounted for on the 

 mere ground of its glutinous character. It has long 

 been well known that butchers and those who are 

 engaged in the slaughter of animals, and are therefore 



