THE SERUM DISEASE IN MAN 601 



from the placenta, which have the property of establishing an 

 an aphy lactic state. 



The Serum Disease in Man. This condition, which is 

 intimately related to supersensitiveness, includes the phenomena 

 which have been observed after the injection of anti-diphtheric 

 and other sera. The real factor is the introduction of foreign 

 protein into the human tissues. As in the case of anaphylaxis, 

 described above, there is here also a period of incubation, of eight 

 to twelve 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 

 or morbilliform. There is usually moderate pyrexia of a 

 remittent type, and sometimes oedema and slight albuminuria 

 are present ; occasionally there are pains in the joints ; there is 

 also often leucopenia, due to a fall in the number of polymorpho- 

 nuclear leucocytes. These symptoms last for a few days and 

 then disappear. Such are the phenomena of the serum disease 

 after a single injection of the foreign serum. There are, however, 

 two other types of reaction described by v. Pirquet and Schick, 

 namely, the immediate and the accelerated reactions. The im- 

 mediate reaction is seen when a large dose of serum has been 

 administered and then after a certain interval of time another 

 dose of serum is injected. This interval is usually from twelve 

 days to eight weeks, though sometimes as long as six months. 

 The symptoms of the immediate reaction, which appear shortly 

 after the injection, or at least within twenty-four hours, are an 

 intense oedema locally, general exanthemata and pyrexia, though 

 the general phenomena are often little marked. The symptoms 

 pass off comparatively quickly, usually within twenty-four hours. 

 The accelerated reaction is also seen after a second injection, 

 and it may occur from six weeks up to many months after the 

 first injection. In the case of the accelerated reaction there is 

 an incubation period, but it is shorter than in the case of the first 

 injection, being usually from five to seven days ; the symptoms 

 resemble those in the ordinary reaction as described above, but 

 are of rather more acute onset and last a shorter time. In the 

 interval from about the sixth week to the sixth month, there 

 may occur both the immediate reaction, and also a few days 

 later an accelerated reaction. 



The phenomena of the serum disease in all probability depend 



