MALTA FEVER, MALARIA, YELLOW FEVER 137 



" At the time this work began, everybody sup- 

 posed that Malta fever was due to effluvia, that it 

 was due to this minute micro-organism finding its 

 way into the air of wards from the sick, or into the 

 air of rooms from drains, sewers, etc., and so 

 causing infection. . . . At one time it was thought, 

 for example, that the Grand Harbour of Malta was 

 the breeding-place of this fever." 



Many researches, therefore, were made on 

 hospital-air, on the Harbour-water, on dust, and 

 so forth : 



" It was found, from these experiments, that the 

 micrococcus was not conveyed either by the air, or 

 from the effluvia, or from the Harbour- water ; nor 

 from dust collected in suspicious places where one 

 might hope to find it, contaminated places ; nor 

 from the air and dust, for instance, of fever wards, 

 or of rooms where cases of the fever had occurred, 

 and so on. All these experiments were negative." 



Then began the gradual tracking-down of the 

 infection to the goats' milk : 



" It was discovered, by animal experiment, that 

 infection could be conveyed by the mouth. This 

 discovery came, as it were, by an accident, at the 

 end. In an investigation of this kind, you naturally 

 examine all the animals round about, in order to 

 find out if any of them harbour the disease. The 

 goat was looked upon by us as the most refractory 

 and the most unsusceptible animal we could 

 imagine. We do not consider that the goat is 

 readily susceptible to human diseases ; it does not 

 even take tuberculosis, which is such a common 



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