150 OKIGIX OF NATURAL IMMUNITY, 



but probably none so clearly as Madsen and Arrhenius, who, 

 while showing that the union is like that of a strong base with a 

 weak acid, such as boric, have cleared the path of certain of 

 Ehrlich's degraded toxines that served only to obscure the view. 



Associated with immunity there is a phenomenon known as 

 agglutination, which, like toxine immunity, obeys the laws of 

 chemical combination. The immobilisation of the bacteria by 

 an agglutinating serum is caused by the formation of a precipitate 

 between the bacterial product and agglutinine under the influence 

 of the residual affinity of a flocculating salt or other substance. 

 Peculiarities in the flocculating action have lately been noted by 

 Dreyer,* who, while comparing some of the actions with those 

 exhibited by chemical substances, such as the combination of gum 

 mastic and ferric chloride, at another place speaks of a destruc- 

 tion of agglutinine by caustic alkalies, which is restored by acids. 

 This is an example of the tendency shown, even among those 

 investigators who incline to the chemical nature of the phenome- 

 non of agglutination, to regard it sometimes in a chemical light 

 and sometimes as a mysterious something with laws of its own. 

 Flocculation has not been deeply studied, especial]}'- with regard 

 to the precipitation of the weak organic acids and bases, but 

 when it shall have been, there can be no doubt that parallels will 

 be found to show that agglutination and precipitation are one 

 and the same thing. 



But in returning to the origin of immunity, it will be necessary 

 to consider the possibility of bacteria passing from the intestine 

 into the tissues. 8chott,t in reviewing the literature of the sub- 

 ject up to 1901, concluded that we w^ere not justified in assuming 

 that pathogenic or non-pathogenic bacteria could pass through 

 the wall of the uninjured alimentary canal. Rogozinski; found 

 that the mesenteric glands always contained bacteria, while the 

 chyle, liver and spleen were free. Falting found that bacteria 



Brit. Med. Journ. Sept. 10, 1904. No. 2280, 564. 

 + Cent. f. Bakt. 1, xxix. 289. 

 : Cent. f. Bakt. 1, Kef. xxxiv. 323. 

 § Cent. f. Bakt. 1, Ref. xxxi. 544. 



