348 BIOLOGY AND HUMAN LIFE 



Overwork 

 Alcohol 



Activity of parasites that exhaust without themselves break- 

 ing out in an acute disease 



3. Reaction of organisms to parasites 



Phagocytosis (white corpuscles swallow invading bodies) 

 Chemical response (the formation of neutralizing or counteract- 

 ing substances ; antibodies) 

 Antitoxins (poison neutralizers) 

 Cytolysins (cell dissolvers or bacteria destroyers) 

 Agglutinins (glue or clot up invading bodies) 

 Precipitins (throw out foreign proteins etc. as solids) 

 Opsonins (modify foreign bodies so that white corpuscles can 

 swallow them) 



4. Uses made of specific reactions 



Tests 



Widal test for typhoid 



Schick test for diphtheria susceptibility 



Tuberculin test for tuberculosis 



Tests for hay fever 



Dick test for scarlet-fever susceptibihty 



Agglutinin and precipitin tests for specific sources of blood 

 stains and other organic materials 

 Vaccinations 



Smallpox 



Cultivated on healthy calves 



P f h -p] I Of ten used together as "triple vaccine" against 



Tx J. I intestinal disorders 



Dysentery j 



Whooping cough 



Boils and pimples 



Common colds 



Diphtheria (toxin-antitoxin) 



Rabies 



From spinal cord of rabbits inoculated with hydrophobia 



5. Measurement of results 



Decline in sickness rate and mortality rate of diphtheria 

 Since discovery of germ 

 Since discovery of antitoxin 

 Since general use of antitoxin 

 Since application of Schick test 



