134 CONTEMPORARY SCIENCE 



in man. Because of their size, perhaps for other reasons, 

 human beings even when sensitive react to the parenteral 

 injection of native proteins less severely than the smaller 

 animal species. And yet lamentable instances, if very 

 few in number, of serious or even fatal anaphlyactic ef- 

 fects have been observed in man. These have occurred 

 especially in connection with the therapeutic employment 

 of curative serums derived from the horse. The greatest 

 danger from this source is at the time of the first injec- 

 tion, for while severe effects do sometimes follow upon 

 a second or subsequent injection, they have never been 

 attended by fatal consequences. Luckily, means are 

 known for anticipating these even infrequent accidents, 

 and of guarding against their dangers without at the same 

 time depriving those in need of the benefits of serum 

 protection or therapy. 



Beside the active state of sensitization another is known 

 which may be termed negative. Thus it has been found 

 that when a sensitive animal is given an injection of a 

 protein which produces a certain degree of anaphylactic 

 effect, but not a fatal outburst, the treated animal can 

 for a time be rendered insensitive. And thus human be- 

 ings who are sensitive, say to horse serum, may be desen- 

 sitized by means of successive small inoculations of the 

 diluted serum, and while in the refractory state thus in- 

 duced receive without risk larger injections of the serum. 



On the other hand, lesser states of anaphylaxis in man 

 are by no means infrequent. To them belong the rashes 

 of "serum sickness" following the injection of curative 

 serums which while annoying are not dangerous, and the 

 very disagreeable manifestations of hay fever and its 

 allied conditions, now attributed to the action of vege- 

 table materials, pollens chiefly, upon the sensitized mu- 

 cous membranes of the nose and throat. Recent studies 

 by Auer have shown that animals sensitized with harm- 

 less proteins, such as horse serum, develop severe local 

 inflammations when from any local cause an extrusion of 



