Stakman * Scientific and Social Development of the World 157 



men in the second half of the 18th years of experimentation and studv. 



century: M. Tillct, Felice Fontana, and The component particles of the smut 



Giovanni Targioni Tozzctti. dust were the contagion, not merely the 



Brilliant pioneers though they were, carriers of it; Prcvost proved that they 



these men were not the fathers of plant were the propagative bodies of the 



pathology, but they deserve almost microscopic plant that causes the dis- 



more credit for having been its grand- ease. 



fathers. It was they who started the Provost undertook to find a remedy 



revolution that eventually modernized for bunt or stinking smut of wheat, 



plant pathology. They substituted sys- a vulgar subject and an unworthy ob- 



tematic observations and experimenta- ject in the ejes of many of the purer 



tion on diseases for scholastic argu- scientists of that time. The methods 



mentation about them. One small but used for controlling bunt were not ef- 



important fact, however, eluded them, fective, so Prevost set out to find a 



By epoch-making experimentation better one. He succeeded, and there 

 Tillet proved conclusively that bunt of is a tablet to his memory in Montau- 

 wheat was contagious, and he demon- ban, France, honoring him for it. But 

 strated that the smut dust, the spores, that is not honor enough. For his ex- 

 carried the contagion, but the nature of perimentation with preventatives drove 

 the contagion which they carried de- him to more basic research on the 

 fied his understanding. Both Fontana nature of what he was trying to prevent, 

 and Targioni said categorically that He found the preventive in copper sul- 

 wheat rust was caused by a microscopic phate and demonstrated that it pre- 

 parasitic plant, but they did not demon- vented the development of a micro- 

 strate it; they inferred it. They could scopic parasitic fungus. In commenting 

 not quite get the idea, sharply percep- on the fact that Tessier regarded fogs 

 tive though they were, that the spores as the cause of rust— a widely prevalent 

 which they observed so carefully and view— Prevost asserts that it is now 

 described so accurately were the repro- proved that they are no more the cause 

 ductive bodies of the rust plant in- of rust than of bunt, for "How could 

 stead of the rust plant itself. fogs be the cause of a plant?" Which 



There was just one more little hill was a very pertinent question. 



to climb, and they did not quite get Was not Benedict Prevost the pio- 



over the top. But they did succeed in neer in establishing the germ theor\' of 



changing man's way of looking at disease? He clearly demonstrated that 



things, and that is one of man's great- a microfungus caused a plant disease, 



est accomplishments, if the new look thus establishing the principle of 



is better than the old. In this case it pathogenesis. 



was. Targioni's comprehension was As a science, plant pathology is 



truly remarkable; and it would have scarcely a hundred years old. It now 



been completely amazing if only he comprises not only a coherent pattern 



could have comprehended the true na- of activities but also a reasonably co- 



ture of spores instead of postulating hesive group of scientists. The early 



that they produced myriads of invisible plant pathologists emerged largely from 



infectious particles. botany and gradually coalesced into 



What is the contagion in smut and groups with a core of common purpose. 



how is rust contagious? These were the A pioneer concrescence, of the massive 



questions provoked by the work of the type, was the American Phytopatholog- 



great triumvirate. Prevost answered the ical Society, 



first part of the question in 1807, after The American Phytopathological 



