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TEE POPULAR SCIENCE MONTHLY 



to five minutes after the injection respiration ceases and the animal dies 

 of asphyxia. The heart keeps on beating for many minutes after all 

 respiration has stopped. Inspection of the lungs shows a remarkable 

 picture; on opening the thorax, the lungs do not collapse as normal 

 lungs do, but remain fully distended and form a cast of the thoracic 

 cavity (see Fig. 1). Their color is pale bluish pink and the lungs are 

 light in weight. The same lung picture was obtained with equal 

 promptness when the vagi were cut or when the central nervous system 

 was destroyed, thus demonstrating that this lung condition was of 

 peripheral origin and independent of the central nervous system for 

 its production. On the basis of experimental evidence which need not 

 be detailed here, Auer and Lewis conclude that this striking lung con- 

 dition is produced by a tetanic contraction of the muscles in the finer 

 bronchial tubes. On the basis of this, atropin was used prophylactically 

 with good results, 72 per cent, of the treated animals recovered, while 

 75 per cent, of their untreated mates succumbed (Fig. 1). The blood- 

 pressure curve in these fatal cases does not resemble that seen in dogs, 

 nor does the blood show a strongly increased coagulation time. 



Fig. 1. The large inflated lungs were obtained from a typical fatal case of 

 horse-serum anaphylaxis in a guinea pig. The small collapsed lungs belonged to an 

 anaphylactic guinea pig of the same lot which was saved by the injection of atropin. 

 This animal seemed normal when killed. The picture shows strikingly the character- 

 istic lung picture of anaphylaxis and the remedial effects of atropin. 



The right vagus nerve had been resected in each guinea pig thirteen days before 

 the toxic injection. 



It will be observed that the important functional disturbances differ 

 in the three species of animals which have been considered above: in 

 the dog, the main noticeable effect is a profound, lasting drop in blood 

 pressure associated with a great increase in the time necessary to cause 

 coagulation; the lungs show no lasting inflation. In the rabbit, the 

 heart stops beating and the cardiac muscle exhibits a total or almost 



