442 THE POFULAR SCIENCE MONTHLY 



we are justified in speaking of the response as an undoubted reaction 

 of anaphylaxis. The three conditions necessary for the employment 

 of this word are fulfilled, and we are dealing with the same phenomena 

 or group of phenomena which the older observers noted and which they 

 called hypersensitiveness, Theobald Smith's phenomenon or anaphy- 

 laxis. If these considerations are followed a field of investigation with 

 sharply defined borders is opened up, and every observer is enabled to 

 judge whether or not his particular patch lies within this territory. 



These criteria yield a sharply circumscribed mass of phenomena 

 which are undoubtedly caused by the same general process, and which 

 may now be further analyzed without any doubt, whether or not they 

 are of anaphylactic origin. The more obvious signs and symptoms 

 have already been established in dog, guinea-pig and rabbit, which are 

 the animals usually employed in laboratory investigation. But it must 

 be continually borne in mind that the characteristic anaphylactic re- 

 sponses of these three species are characteristic only when they are 

 obtained after the second injection of a soluble proteid; the profound 

 drop in blood pressure in the dog, the large immobilized pale lungs in 

 the guinea-pig and the loss of irritability and contractility of the heart 

 muscle in the rabbit, do not occur when a harmless soluble proteid like 

 horse serum is injected for the first time; they only appear when the 

 injection is repeated after the period of incubation, and this peculiarity 

 characterizes them as anaphylactic and differentiates them at the same 

 time from similar reactions which occur on first injection of a large 

 number of substances. 



These considerations render clear, perhaps, why it is not justified 

 at present to admit that those cleavage products of proteids which cause 

 a similar disturbance on first injection really produce true anaphylaxis, 

 for as soon as this assumption is granted the three characteristic condi- 

 tions of anaphylaxis which give this symptom complex an independent 

 existence by delimiting it from similar complexes, is obliterated. More- 

 over, the clean and outspoken functional responses found in the three 

 animal species in anaphylaxis lose their diagnostic character and inde- 

 pendence, and fall back into the ruck, indistinguishable from a mass 

 of similar reactions. This is surely a heavy price to pay for an exten- 

 sion of the meaning of anaphylaxis, especially as this extension is not 

 necessary. Even when true anaphylatoxins are isolated, no such broad- 

 ening of the term will be necessary, for only those substances can be 

 considered true anaphylatoxins which are isolated biologically from the 

 tissues and circulatory juices of a case of true anaphylaxis; and these 

 substances must practically not be present in normal animals, but when 

 injected into these normal animals the anaphylactic symptoms and 

 signs characteristic for the species employed must be obtained. Such 

 substances may be the product of proteid cleavage, but they will bear 



