554 Crown Gall-Animal Cancer Analogy 



man is caused by a coccus conveyed in milk from diseased goats ; the spiro- 

 chaete of African relapsing fever is transmitted by a tick; the cause of 

 undulant fever, another spirochaete, is carried in the body of a louse and 

 is transmitted by scratching; and so on. The list is a long one. Referring 

 again to the Rocky Mountain spotted fever, transmitted by infected ticks, 

 Spencer and Parker of the Hygienic Laboratory, have discovered a pro- 

 tective vaccine. . . . 



Smith concluded his elaboration of this subject by the paragraph 

 on " carriers of plant parasites," quoted in the last chapter. 



His proximity to the Hygienic Laboratory of Washington 

 enabled him to keep in close contact with the progress made 

 there in medical studies. Practically all of our knowledge of 

 tularemia came from this laboratory,^* and at least once Dr. 

 Edward Francis, surgeon of the United States Public Health 

 Service, consulted with Smith. On January 24, 1921, Smith in 

 his diary described their conference: 



He brought slides of a pathogenic organism (schizomycete) for me to 

 photomicrograph. He has obtained it from the Deer fly fever of Utah. 

 This also attacks jack rabbits and can be inoculated into guinea pigs. It 

 attacks the spleen of jack rabbits and if the cut spleen of a diseased rabbit 

 is rubbed on the shared skin of the pig it contracts the disease through 

 the lymphatics. He himself contracted the disease during his two year 

 study. 550 rabbits were shot and dissected and the disease found in 18. 



According to Smith, Dr. Francis, during 1919-1920, had isolated 

 in Utah Bacterium tularense from seven human cases and seven- 

 teen jackrabbits, and called the disease " Tularemia." In 1921 

 he and Dr. Mayne "" proved the deer-fly {^Chrysops discalis^ to be 

 a transmitter of the infection of Tularemia to laboratory animals " 

 and by 1926 this fever had been found in man in the District of 

 Columbia and thirty-one states.®^ Among the list of animal dis- 

 ease carriers, the other transmitters were mentioned; and in Chap- 

 ter X a reference to Director McCoy's discovery in 1911 of Bac- 

 tenum tularense in ground squirrels dead of an epidemic disease 

 resembling plague appeared. 



The foregoing paragraphs indicate what Smith believed. The 

 reader is cautioned not to regard their factual content as complete 

 condensations of the knowledge to the present time. Since those 



**The National Institute of Health, Science 107: 615, June 11, 1948, in which 

 many other scientific achievements of the Institute are listed. 

 ^^ Fifty years of pathology, op. cit., 40-41. 



