600 IMMUNITY 



facts can be equally well explained by the combination, which 

 occurs either locally or generally, of the antigen with anti-sub- 

 stance in the serum, which combination when acted upon by 

 complement gives rise to the poisonous substance. At present 

 it is not possible to make a definite statement on the subject. 

 There is no doubt that the supersensitive condition must play an 

 important part in the clinical manifestations of many diseases. 

 For example, the sensitiveness of tubercular patients to tuberculin 

 shows that the symptoms in this disease are evidently produced 

 by the absorption from the tubercular foci of a smaller amount 

 of toxin than would be necessary to produce effects in a normal 

 individual. And the sensitiveness of the conjunctiva in typhoid 

 fever to the products of the bacillus suggests that in this disease 

 also supersensitiveness plays an important part. It is also 

 possible that the repeated absorption of bacterial products may 

 lead to toxic symptoms when tested in the usual manner, whilst 

 . they prove harmless by single injections. There is thus a good 

 deal in favour of Friedberger's view that anaphylaxis corre- 

 sponds to an "acute infection," whereas ordinary infection is of 

 the nature of a gradual and protracted anaphylaxis. The 

 essential factor in antibacterial immunity is a disintegration of 

 the bacterial protoplasm, and the essential agents in anaphylaxis 

 are the split-products of proteins. The toxic agents in many 

 bacterial infections may thus be of common nature ; what con- 

 stitutes their apparently specific characters may depend upon the 

 site of the organisms, the mode of absorption of their products, 

 etc. The phenomena of anaphylaxis may thus in part explain 

 the symptoms of a disease, and may, on the other hand, be an 

 accidental result of the process of immunity. The phenomena 

 of. hay fever probably belong to the same class, being the 

 result of acquired anaphylaxis to a vegetable protein, and 

 some evidence has been brought forward that puerperal 

 eclampsia is produced by the absorption of proteins from the 

 placenta, which have the property of establishing an anaphy- 

 lactic state. 



The Serum Disease in Man. — This is another example of 

 anaphylaxis. There is here also a period of incubation, of eight 

 to twenty days on the average ; after which, in a certain proportion 

 of cases (in about 20 per cent.) after the injection of a fairly 

 large amount of horse serum, a group of characteristic symptoms 

 appear. There may be as prodromal symptoms, swelling and 

 tenderness at the site of injection, and in the corresponding 

 lymphatic glands, and thereafter general exanthemata appear. 

 These are usually of an urticarial type, but may be erythematous 



