CHAPTER XVI [528] 



HISTORICAL SKETCH OF OUR KNOWLEDGE 

 ON IMMUNITY 



Methods used by savage races for vaccination against snake venom and against 

 bovine pleuropneumonia. Variolisation and vaccination against small-pox. 

 Discovery of the attenuation of viruses and of vaccinations with attenuated 

 micro-organisms. Theory of the exhaustion of the medium as a cause of 

 acquired immunity. Theory of substances which prevent the multiplication 

 of micro-organisms in the refractory body. Local theory of immunity. Theory 

 of the adaptation of the cells of the immunised organism. 



Observations on the presence of micro-organisms in the white corpuscles. History 

 of phagocytosis and of the theory of phagocytes. Numerous attacks upon this 

 theory. Theory of the bactericidal property of the body fluids. Theory of the 

 antitoxic power of the body fluids. Extracellular destruction of micro- 

 organisms. Analogy between bacteriolysis and haemolysis. Theory of side- 

 chains. 



Progress of the theory of phagocytes. Attempts to reconcile it with the humoral 

 theory. Present phase of the question of immunity. 



As protection against disease is one of the most important amongst 

 those questions which are engrossing the attention of humanity, it is 

 natural that very great attention should have been devoted to it 

 from the most remote times. We see primitive races, the ordinary 

 layman, medical men, legislators and even the most subtle thinkers 

 devoting their energies to the solution of the problem of immunity 

 against poisoning and against infections. Historical science will 

 never reveal to us the earliest sources of our knowledge on this 

 question, so remote are their origins. The wide distribution of 

 several methods for protecting man and cattle against certain diseases 

 clearly proves that the origin of this practice dates from a very early 

 period. 



The frequency of venomous snakes in many countries has inspired 

 a dread of these reptiles, and this must have led to the search for 



