10 VACCINE AND SERUM THERAPY. 



or another of these conditions. Resultant of this tendency of 

 microorganisms to produce particular kinds of conditions, the 

 prognosis for infections varies with the species of microorganism 

 producing the lesions or condition. 



The same species of microorganism will not always be distri- 

 buted in an identical manner; the location of the lesion and the 

 condition produced varying with the properties of the particular 

 strain in question and the particular part of the body infected. 

 The appearance of general symptoms will vary greatly with the 

 rapidity of the absorption of the toxin. Experimentally, intra- 

 venous and intraperitoneal injections of microorganisms are fol- 

 lowed by symptoms earlier and more consistently than are sub- 

 cutaneous injections. 



The number of bacteria invading the tissues is of some im- 

 portance. If few bacteria are present they may die without 

 producing -infections, while if larger numbers are present some 

 of them will be likely to grow and produce disease. 



At the point of infection, or portal of entry, the effects pro- 

 duced will vary with the infecting organism, some producing 

 specific forms of inflammation along with those common to many 

 bacteria. Even with the same species of microorganism the 

 reaction will vary with the prevalence and virulence of the invad- 

 ing organism and with the anatomical structure of the part of 

 the body involved. The local reaction, however, is not only pro- 

 duced when the bacteria enter the tissues of the body but also 

 when the "toxins produced by the microorganism are present in 

 the tissues. The most commonly seen reaction at the portal of 

 entry is that which results in pus formation, in which, due to 

 chemotaxis, leucocytes accumulate. While a local reaction is 

 usually produced at the portal of entry of bacteria, the reaction 

 at times may be slight or absent entirely. A local reaction when 

 produced is generally regarded as of importance in the protection 

 of the body against the invasion of bacteria. 



Besides the local reaction, general reactions usually follow 

 in all severe infections. General reactions occur as a result of 

 the action of toxins produced by the microorganisms when they 

 are absorbed by body tissues. The general symptoms produced 

 vary according to the location of the primary lesion, the extent 

 of the process, the peculiarities of the organism, and the resistance 



