188 NUCLEIC ACIDS AND THE NITROGENOUS BASES 



logical saline solution and perfused through excised bloodvessels the 

 muscle-fibers of the vessels contract, causing a decrease in their 

 diameter, but when er gamine is injected intravenously, the effect 

 upon the majority of the vessels in situ is just the reverse, and the 

 blood-pressure undergoes a profound decrease due to their dilation. 

 The vessels of the lungs, heart and kidneys, however, are constricted. 

 An exceptionally interesting action of ergamine is that of inducing 

 spasmodic contractions of the Bronchioles when administered in 

 relatively large doses. Thus 0.5 milligrams of ergamine intra- 

 venously injected will kill a guinea-pig in a few minutes, and the 

 cause of death is asphyxiation, which is due to closure of the bron- 

 chioles, preventing the passage of air into or out of the lungs. Post- 

 mortem examination shows that the lungs are permanently dilated 

 (Emphysema). Now this is the condition which, in a milder degree, 

 is responsible, in human beings, for the respiratory distress in Asthma. 

 It may further be brought about by peptone-poisoning or by inducing 

 Anaphylactic Shock. 



When a non-toxic foreign protein, for example egg-white, is injected 

 hypodermically or into the circulation of an animal, if the first dose is 

 followed within a few days by a second, that in a like period by a 

 third, and so forth, no harmful results ensue, and the animal gradually 

 acquires Immunity to the protein. If, however, after the injection 

 of the first dose of protein a considerable period, e. g., three weeks, be 

 allowed to elapse before the second is administered, if the second 

 dose be sufficiently large, a condition of " anaphylactic shock" is 

 induced which is frequently fatal. The cause of death is asphyxiation 

 due to spasmodic contractions of the bronchioles and it is believed that 

 the preliminary " sensitization" of the animal has endowed its tissues 

 with the ability to so rapidly decompose the foreign protein that upon 

 injection of the second dose dangerous quantities of toxic peptones or 

 other products of protein decomposition are rapidly formed. The 

 resemblance between the symptoms of ergamine poisoning, peptone 

 poisoning, asthma and anaphylactic shock is so striking as to suggest 

 a common cause and the view has been advanced that all of these 

 phenomena are attributable to the liberation of j8-iminazolyl ethyl- 

 amine in the blood or tissues, the source of the substance being the 

 Histidine radical in proteins or peptones. On the other hand it has 

 not been conclusively shown that peptones themselves or peptide- 

 derivatives of /3-iminazolyl ethylamine may not produce like effects. 

 At any rate a part of the symptoms of anaphylactic shock are not 

 attributable to ergamine, because this substance does not render 

 blood incoagulable, while incoagulability of the blood is one of the 

 symptoms of profound anaphylactic shock and of peptone poisoning. 



The possibility of the formation of /3-iminazolyl ethylamine from 

 proteins in the lower intestine by the action of fecal bacteria may 

 enable us to trace certain forms of asthma to an intestinal source. 

 The majority of cases appear, however, to be undoubtedly anaphy- 



