24 DEVELOPMENT OF BACTERIOLOGY 



If there were any doubts left in the minds of the scientific world 

 as to the fallacy of the theory of spontaneous generation, after the 

 work of Pasteur, they were dispelled by the work of Tyndall. 

 Tyndall proved that in an atmosphere devoid of dust, as on the 

 tops of mountains and in some ingeniously constructed- boxes used 

 by him, perishable substances, such as beef tea, if sterile when placed 

 in such an atmosphere, will keep for an indefinite period. 



Smallpox. Smallpox was formerly looked upon as practically 

 unavoidable by all members of the human family, as is seen from a 

 popular saying current in Germany in the eighteenth century: 

 "von Pocken und Liebe bleiben nur wenige frei," from smallpox and 

 love few remain free. 



Concerning smallpox Macaulay wrote in referring to the death of 

 Queen Mary from the disease in 1694: "The havoc of the plague 

 had been far more rapid; but plague had visited our shores only 

 once or twice within living memory, and the smallpox was always 

 present, filling the churchyards with corpses, tormenting with 

 constant fears all whom it had not yet stricken, leaving in those 

 whose lives it spared the hideous traces of its power, turning the 

 babe into a changeling at which the mother shuddered, and making 

 the eyes and cheeks of the betrothed maiden objects of horror to the 

 lover." 



For the different condition which exists today in civilized countries 

 where the fear of smallpox is nearly as remote as that of leprosy, 

 Edward Jenner (1749-1823) is chiefly to be thanked. His attention 

 was at first directed to the subject by the remark of a young girl: 

 "I cannot take smallpox for I have had cowpox." After consider- 

 able labor and opposition he developed arid gave to the world, 

 without monetary consideration, his vaccine which has all but 

 banished from the w r orld the dreaded disease smallpox. 



Anthrax. As early as 1863 investigators had seen in the blood 

 of some animals that had died of a disease known as anthrax, a very 

 small rod-like organism which permeated all the capillaries. Their 

 experiments showed that the blood from such an animal, when 

 injected into the veins of a second animal, caused it to die of the 

 same disease. But they found that there were times when the organ- 

 ism could not be discovered in the blood of the dead animal, although 

 injection with blood from this animal would cause the death of 

 another. This fact left a doubt in the minds of thinking men as to 

 whether this rod-shaped organism was the cause of the animal's 

 death or whether it was "some invisible element in the blood." 

 Not until thirteen years later was this fully settled by the work of 

 Robert Koch. He not only saw the rod-shaped organism, but 

 obtained it free from all other substances, and proved that it was the 

 specific cause of the disease. This was followed by many other dis- 

 coveries, until today it is known that practically all diseases are due 



