HISTORY. 

 THE EARLIEST WORKERS. 



The earliest workers in any field of science deserve special consideration. They are 

 like pioneers in a new country, and are usually poorly equipped for their task. If, under 

 such circumstances, a man makes substantial additions to human knowledge, he deserves 

 corresponding credit. Such a man is what we might call a born investigator. He is able 

 not only to see his problem as a whole, but also to see it in its parts, and to determine 

 their interrelations. 



The earliest investigators in the field of plant-diseases due to bacteria were Burrill, 

 Prillieux, Wakker, Comes. These men wrought independently — the first in the United 

 States, the second in France, the third in the Netherlands, and the fourth in Italy. All 

 are yet living. To these names I would add that of Woronin, whose one contribution was 

 the discovery of bacteria in the root-nodules of the Leguminosae. 



Burrill's principal contribution consists in the discovery of the bacterial origin of pear- 

 blight. The disease had been known in the United States for a hundred years and at times 

 had been very destructive. A multitude of hypotheses had been propounded to explain 

 the mysterious phenomenon, none of which really explained. Into this obscurity and con- 

 fusion Burrill let a flood of light by addresses and papers published between the years 

 1878 and 1883. So far as this country is concerned, he may be said to have won over the 

 public in 1881. Many things yet remained to do — things afterwards done by Arthur and 

 Waite — ^but on the main proposition, namely, that pear-blight could be attrijauted only to 

 bacteria, Burrill's experiments appeared to be conclusive. Burrill's work was done at the 

 University of Illinois, located at Urbana, where he holds the chair of Botany. Burrill 

 subsequently published short papers on several other bacterial diseases, i. e., potato-rot, 

 disease of maize, and disease of broom-corn. But to none of these subjects does he seem 

 to have been able to give his undivided attention, most of the conclusions depending in 

 part at least upon the work of students. He Hkewise published papers on fungi, notably 

 the Uredineae of Illinois, in connection with Seymour. 



PrilUeux published his first paper on a bacterial disease of plants in 1879. This con- 

 sisted of an account of a microscopic examination of wheat-kernels in which he found 

 clouds of a micrococcus-like organism eroding the interior into distinct cavities. This is 

 generally known in literature as the rose-red disease, or Micrococcus disease, of wheat- 

 kernels. Prillieux did not make any pure cultures or inoculations, and the disease seems 

 to be a rather uncommon one, so that no one has been able in recent years to control his 

 observations, but the account of his microscopic examination is explicit and his figures are 

 not obscure. Subsequently, Prillieux published on various other diseases of plants ascribed 

 to bacteria, e. g., on the olive-tubercle and the Aleppo pine knot, but most of his energies 

 have been given to the elucidation of diseases of a fungous nature. His text-book on 

 diseases of plants is well known. He is professor at I/'Institut National Agronomique and 

 was formerly in charge of the plant pathological laboratory. No. 1 1 Rue Alesia in Paris. 



Wakker published his first paper on the yellow disease of hyacinths in 1883. Subse- 

 quently he published four other papers on this disease, the last in 1889. For a long time 

 his statements, mostly in Dutch, were overlooked or not generally accepted as conclusive, 

 but none of the early work was better done, and numerous experiments made by the writer 

 have shown that he was entirely right in his main contentions. The yellow disease of 

 hyacinths is a genuine bacterial disease and can be induced in the bulb by inoculating the 



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