THE COURSE OF INFECTION 139 



unless the cells are aroused and stimulated, by judicious administration 

 of bacterial vaccines, to produce an oversupply of antibodies, the host 

 shows progressive emaciation and weakness. 



The Systemic Reaction to Infection. It is not within the scope of 

 this book to discuss the various symptoms of infection, and we will 

 limit ourselves to a brief discussion of the most important, namely, the 

 febrile reaction. 



According to Vaughan, the fever of infection is due mainly to the 

 toxic split protein resulting from the action of the protective proteolytic 

 ferments upon the new bacterial protein. This observer and his asso- 

 ciates were able, by the injection of multiple doses of protein derived 

 not only from the typhoid bacillus but from various vegetable and 

 animal proteins, to reproduce experimentally in rabbits a febrile reaction 

 known as protein fever, and which is not unlike typhoid fever. This 

 induced fever may continue for weeks, and is accompanied by increased 

 nitrogen elimination and gradual wasting; it is followed by immunity, 

 and the serum of immunized animals digests the homologous protein 

 in vitro. As has repeatedly been stated, Vaughan regards the split toxic 

 product as the cause of the general symptoms of infection, the special 

 and characteristic symptoms and lesions of the different diseases de- 

 pending upon the site where the bacterial proteins have been deposited, 

 and where they are,, in large part at least, digested. 



In addition to this toxic action of split protein, fever may be due 

 (a) to the unusual activity of the cells supplying the proteolytic enzymes; 

 and (6) to the cleavage of the foreign bacterial protein by these ferments. 



The fever of infection, therefore, is caused by the toxic action of 

 pathogenic parasites, both bacterial and animal forms, upon the body- 

 cells and heat-regulating centers. It must be regarded by itself as a 

 beneficent phenomenon, inasmuch as it marks a reaction of the body- 

 cells to toxic agents, for the purpose of neutralizing these and, by the 

 development of antibodies, ridding the body of foreign substances. 



