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 condition 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 characteristic 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