SECTION III 
CHAPTER XXVII 
DISEASES OF UNKNOWN CAUSATION 
Smallpox 
Smallpox, the most virulent of all infectious diseases, 
used to be a veritable scourge, but today is practically 
subdued, thanks to the epoch-marking discovery of 
Jenner, who, in 1798, introduced vaccination for small¬ 
pox and thus conferred an everlasting obligation upon 
mankind. The vaccine is prepared from the infectious 
material taken from the calves which have been inocu¬ 
lated with the material from human smallpox. 
Measles 
Measles is essentially a disease of childhood. Nothing 
definite is known about the organism causing it. 
Mumps 
No specific organism has been discovered for mumps. 
Scarlet Fever 
Scarlet fever is also essentially a disease of childhood. 
Several investigations have claimed to have discovered 
the specific organism, the last one being Mallory, of 
Boston, but so far no definite conclusions have been 
drawn. 
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