444 TEE POPULAR SCIENCE MONTHLY 



toms either develop after a few hours, the " immediate reaction," or 

 after a few days, the " accelerated reaction." As the time interval 

 between the injections increases the " immediate reaction " no longer 

 appears, but the " accelerated reaction " still occurs and has even been 

 noted when the second injection followed seven years after the first. 

 The symptoms which characterized the " accelerated " reaction are 

 similar to those already described, with this difference that they occur 

 suddenly, and disappear swiftly within approximately a day. The 

 " immediate " reaction is somewhat different and characterized by a 

 local edema at the site of injection which slowly increases and reaches 

 its maximum within about twenty-four hours, and disappears within 

 two to five days. Associated with this local reaction there is high 

 fever, and the skin shows crops of transitory eruptions of varying char- 

 acter. In a small proportion of all cases the immediate reaction shows 

 a grave picture, there is nausea and vomiting, and at times even collapse. 



The similarity between serum disease and anaphylaxis was early 

 noted by v. Pirquet and Schick. The specific local edema, for example, 

 is exactly analogous to Arthus's phenomenon in rabbits; the non-fatal 

 collapse cases also are similar to the results which Arthus obtained in 

 rabbits where he noted a strong drop in blood pressure. 



There is another class of severe reactions, fortunately rare, which 

 occur suddenly when a patient is injected for the first time with serum. 

 The symptoms bear a striking analogy to those observable in lethal 

 anaphylaxis in guinea-pigs and rabbits. Some individuals show a 

 marked respiratory distress of an asthmatic type with cyanosis, similar 

 to guinea-pigs, and others again show symptoms where the respiratory 

 involvement is not so pronounced, but where cardiac weakness predom- 

 inates. These cases often end in death. Examination of the history 

 of such individuals often shows that they were subject to asthma, or 

 possessed a peculiar idiosyncrasy to the odor of horses which brought 

 on the symptoms of hayfever and asthma. Cases of this kind are 

 probably examples of anaphylaxis in spite of the apparent absence of 

 any sensitizing injection, for this state of sensitization could easily be 

 attributed to inheritance or to a gradual sensitization via the lungs or 

 the stomach. It is well-known, for example, that a sensitized guinea- 

 pig will transmit this property to her offspring, and we may assume 

 that this also plays some role in human cases; moreover Eosenau and 

 Anderson have shown that sensitization may be accomplished in guinea- 

 pigs by feeding raw horsemeat, and more recently Eosenau and Amoss 

 reported that they were able to sensitize guinea-pigs for human serum 

 by injecting the infinitesimal amount of organic material found in the 

 expired breath of human beings. These experimental facts render it 

 quite probable that all these cases where the first injection of horse 

 serum produced alarming symptoms or even death, were sensitized in 



