602 IMMUNITY 



hence the reaction is accelerated as compared with the reaction 

 after the first injection. 



Practical Eesults — Desensitisation. — In view of the common 

 use of curative serum, anaphylaxis has come to have considerable 

 practical importance, especially in connection with intravenous 

 injection, as by this route the dangerous dose is a fraction of 

 that by subcutaneous injection. With regard to the possibility 

 of there being a primary or natural supersensitiveness, inquiry 

 should be made as to tendency to asthma or hay fever, or sensi- 

 tiveness to the presence of horses in the vicinity, as these have 

 been found to be associated conditions, and the existence of 

 Graves' disease has been recorded as another. Then with regard 

 to the acquired variety, information should be obtained as far as 

 possible regarding previous serum injections. The existence of 

 supersensitiveness can, however, be demonstrated by the test for 

 skin "allergy." A small quantity, say '25 c.c, of sterile horse 

 serum is injected by a hypodermic needle into the dermis — not 

 subcutaneously. The minute local swelling which results from 

 the presence of the fluid soon passes off. But in the case of a 

 positive reaction there occurs, usually within five to thirty 

 minutes, an urticarial patch, which may be followed by a 

 distinct vesicle and is often surrounded by an erythematous 

 area, an inch or more in diameter. If no reaction occurs within 

 forty minutes the absence of supersensitiveness may be inferred. 

 If a positive reaction is obtained, means must be taken to de- 

 sensitise the patient, i.e., to produce anti-anaphylaxis ; and this 

 is accomplished by introducing initial small and then gradually 

 increasing doses of serum. In the hospital of the Rockefeller 

 Institute, where large intravenous doses of serum are given in 

 the treatment of pneumonia, the initial desensitising dose is 

 •025 c.c. given subcutaneously, and this amount is doubled 

 every half-hour. If no reaction follows the administration of 

 1 c.c, the subsequent doses are given intravenously, commencing 

 with "1 c.c. and doubling the dose every half-hour till 25 c.c. 

 in all have been given in these small doses. Such a method, 

 however, takes a considerable number of hours and is not justifi- 

 able in a case of tetanus, where a large amount of serum should 

 be given intravenously or intrathecally as soon as possible. The 

 following method, given in the War Office memorandum, should 

 be followed : 5 c.c. of the anti-serum are diluted with 50 c.c. 

 of normal salt solution. Of the mixture 1 c.c. is injected intra- 

 venously ; this is followed four minutes later by 3 c.c, two 

 minutes later by 10 c.c, and two minutes later again by 25 c.c. 

 Then after ten to fifteen minutes the full dose may be given 



