WHAT MEDICINE HAS DONE AND IS DOING FOR THE RACE 439 



disease. Its adoption against infection with enteric (typhoid 

 and paratyphoid) fever, due to the work of Almroth Wright, 

 was as already mentioned, crowned by phenomenal success 

 in the Great European War (1914-1918) and has been 

 employed in other diseases. 



Prophylactic or protective serums render the individual 

 into whom they are hypodermically injected immune to the 

 diseases caused by the viruses which have set up changes 

 in the animals from which the serum is obtained. The blood 

 serum of the animals thus treated contains so-called 

 antibodies which antagonize the toxins or poisons pro- 

 duced by the viruses; in this way passive immunity is 

 produced, and contrasts with the active immunity which 

 results when vaccines or emulsions of dead viruses are 

 injected, the tissues of the person so vaccinated being thus 

 stimulated to produce the specific (i.e. corresponding to the 

 particular virus) antibodies. Antidiphtheritic and anti- 

 tetanic serums are well-estabhshed examples. Various other 

 serums have been used in the same way (see Chap, xvii). 



An important step is the method of being able to determine 

 whether or not an individual is susceptible to certain 

 infections, and therefore hkely to contract them when 

 exposed to them. This immunological reaction is in practical 

 use in diphtheria (the Schick test) and in scarlet fever 

 (the Dick test), and can be applied to the inmates of schools; 

 those children who are thus found to be unprotected against 

 either of these two diseases can then be injected with 

 antidiphtheritic or antiscarlatinal serum, and so rendered 

 immune to these infections for a time. In this way epidemics 

 in schools can be prevented. • 



Curative Antitoxic Serums. The cure of diphtheria by the 

 subcutaneous injection of the blood serum of an animal, 

 usually the horse, previously immunized or rendered 

 insusceptible to the bacillus of diphtheria, has largely 

 robbed the disease of its terrors. This remedy was the 

 result of careful bacteriological research involving animal 

 experiments by Behring. Antitetanic serum, produced in an 

 analogous way by Kieasato, is the best method of treating 

 tetanus. Cerebrospinal fever (meningococcic meningitis) and 

 one form of pneumonia (that due to type i pneumococcus 



