44Q • THE POPULAR SCIENCE MONTHLY 



pig which succumbs acutely to an intravenous injection of horse serum, 

 and which are diagnostic, when properly considered, of true anaphylaxis 

 in this animal. These lungs owe their state to a tetanic contraction of 

 the bronchial muscles, so that the enclosed air is imprisoned in the 

 alveolar sacs and can not escape even when the lungs are completely 

 excised (see Fig. 1). Now, any adequate stimulus which causes an 

 enduring contraction of these muscles while respiration goes on will 

 produce a greater or less approximation to the lung picture of ana- 

 phylaxis. Such adequate stimuli are furnished by a large number of 

 substances, of which we may mention muscarine, eserine, pilocarpine, 

 digitaline, veratrine, morphine barium chloride and the salts of many 

 heavy metals (Dixon and Brodie). Nobody, however, would state that 

 the substances cause anaphylaxis, that they are anaphylatoxins, even 

 though they do produce apparently a lesion of anaphylaxis, for it is 

 perfectly obvious to every one that it is inadmissible to conclude from 

 the identity of reaction produced (in the example chosen, the anaphy- 

 lactic lung) an identity of the causative agents, as this leads to the 

 ridiculous conclusion that eserine, muscarine, etc., are identical. The 

 same reasoning is applicable to the degradation products obtained by 

 chemical or biological means from proteids. It is not surprising that 

 decomposition products of the infinitely complex proteid molecule should 

 yield substances which are toxic to an organism, and which produce 

 anatomical and functional changes similar to those observed in ana- 

 phylaxis, but this does not permit the conclusion that the same decom- 

 position products are formed and exert their actions in true ana- 

 phylaxis ; such reasoning commits the same error which was mentioned 

 before. It must be insisted that an identity in the biological response 

 caused by a variety of substances permits only the conclusion that these 

 substances are functionally identical, not that they are chemically or so 

 to say, morphologically identical. This confusion is widespread, and 

 at present dominant; it is especially due to the per se valuable and 

 interesting contributions of Friedberger and his colaborers. Fried- 

 berger is convinced that the poisonous mixture which he produces by 

 biological methods in vitro is identical with the causative agent or 

 agents in true anaphylaxis, and in most of his recent work the symptom 

 complexes studied were not true anaphylaxis, but the symptoms pro- 

 duced on first injection by his anaphylatoxin. 



The question has probably occurred to the reader why this problem 

 was not approached directly, why, for example, the serum of animals 

 in anaphylaxis was not examined for the presence of these degradation 

 products which are said to play such an important role. The test can 

 easily be made, for the split products of proteids which have an albu- 

 mose or pepton character give the biuret reaction. But no investigator, 

 as far as I am aware, has been able to obtain more than a very feeble or 



