SCIENCE AND THE EMERGENCE OF MODERN AMERICA 



probably identical with those seen by Stiles in 1869, but probably unlike 

 those of Babes (1888) because the latter claimed to have succeeded in 

 cultivating the organism he had observed. In the longer report of 1891 

 Smith, with Kilborne, reported on a more extensive and thorough series 

 of transmission experiments in which four animals were infected by the 

 direct application of ticks. Further, they had placed southern cattle in 

 pens with northern stock — in some cases after the removal of ticks, 

 while in other enclosures the ticks were left on the infected animals. 

 Also, native cattle were kept in fields in which infected ticks had been 

 scattered on the ground. The report which is one of the classics of medi- 

 cal literature, established beyond question the role of the tick as the car- 

 rier of the disease. And not the least of the achievements of these 

 experiments was the observation that the infection could pass, in ticks 

 from mother to offspring, a new and extraordinary phenomenon of 

 parasitism which has found its analogy in tick infection with the Rickett- 

 sia of Spotted Fever. It is certainly not a disparagement of Smith's 

 greatness to correct the erroneous impression created in some popular 

 accounts which belittle the merits of his associates, by stating that these 

 fundamental discoveries were in fact collaborations between a group of 

 well-trained and intelligent men, rather than entirely the work of Smith 

 alone. In doing so it is quite certain that we are stating the case in the 

 manner in which he would have wanted it told. Moreover, from what 

 we know of him and his experimental acumen, it seems more than likely 

 that his was the leading spirit in this collaboration by which, for the 

 first time, the complete cycle of transmission of disease by insects was 

 established. It is true, of course, that as early as 1877, Manson had dis- 

 covered that embryo filaria, taken up from the blood of infected men 

 by mosquitoes, developed in the insects into the final larval stages. But 

 Manson's studies did not show how the filaria again reached man. . . . 

 The investigations of Smith and his collaborators were, therefore, the 

 first to establish the complete cycle of transmission by arthropod vectors 

 — a discovery which represents one of those fundamental steps forward 

 that alter the entire course of a science, and which has practical conse- 

 quences of inestimable and permanent importance. We have presented 

 this particular work with a certain degree of emphasis upon the parts 

 played by others than Smith and upon the significance of earlier dis- 

 coveries which undoubtedly helped to shape Smith's thoughts and ex- 

 periments. 



D. 



THE SHIFT TO THE PROBLEM APPROACH- 

 CHARLES W. DABNEY 



CDuring the 1880's and 1890's the Department of Agriculture went 

 through a distinct evolution in its organization. In place of the divisions 

 representing academic scientific disciplines, the Department developed 

 new bureaus around distinct problems. Scientists of more than one dis- 



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