ANTI-BODIES 149 



infection is conveyed in some special way, e.g. by 

 mosquitoes in malaria and in yellow fever. Nor is 

 infection necessarily confined to one mode of entrance ; 

 in plague, for example, infection by the skin is com- 

 monest in some epidemics, but it is not infrequent by 

 the respiratory, and may occur by the digestive, tract. 

 The infecting agent may remain localised, giving rise to 

 a local infection, or it may be widespread through the 

 body, a septiccemia 1 or general infection. The absorption 

 of chemical products from a local site of infection may 

 produce general symptoms ; this is intoxication, as occurs 

 in cholera, in which the microbe is limited to the bowel, 

 in the early stage of diphtheria, in which the diphtheria 

 bacillus is limited to the membrane, and in a local abscess. 

 Fever is usually one of the results both of intoxication 

 and of general infection. 



Infection, if recovery ensues, is usually followed by 

 remarkable alterations in the blood and tissues. One 

 of these is the production of immunity or insusceptibility 

 to the same infecting agent ; this will be considered later 

 (p. 195). Agglutinins, substances which cause clumping 

 of the infecting organism, are also generally produced 

 (p. 185). 



Anti-Bodies 2 



Another remarkable property, and one of considerable 

 importance in immunity, conferred by the injection into 

 an animal of complex substances, such as bacterial toxins, 

 bacteria, blood- corpuscles, cells and cellular proteins, 

 ferments, etc., is the development of anti-bodies. Thus 



1 " Septicaemia " and " a septicaemia " have different meanings. The 

 former is applied to a general infection with the so-called septic 

 organisms, the latter to a general infection with any organism. 



2 All the subjects dealt with in the subsequent portion of this chapter 

 are discussed in detail by Emery, Immunity and Specific Therapy, 

 1909. 



