43 



It is doubtful whether the disease mentioned here as canker bears any 

 resemblance to the outgrowths at present called canker. It is certain, how- 

 ever, that woody excrescences were also observed. If actual canker swell- 

 ings are not concerned here, yet the phenomena may well have been 

 meant, which we would now call knarls. Theophrastus found this kind of 

 swellings in olive trees and called them nails or scurf (loxas-lopas) because 

 they represent bowl-shaped nails on the trees. Sprengel says of these nails, 

 that they have occurred recently very abundantly on the olive trees in Italy. 

 They appear as round, warty outgrowths of the bark, depressed in the centre 

 like a bowl. Among them may also be found similar swellings of the wood 

 body. 



It is scarcely credible that the points of view expressed by closely ob- 

 servant scholars of Aristotle, concerning the phenomena of disease here men- 

 tioned, changed essentially in the course of the following centuries, for other- 

 wise the celebrated encyclopaedist Plinius Secundus'. who lived from 

 23 to 79 A. D. and who possessed a wide knowledge of literary sources, 

 would have brought forward further material at the time he recorded scien- 

 tifically the statements of Cato (de re rustica) and others as to the influence 

 of the stars and the death of trees resulting from cold, heat, unfavorable 

 position, soil, fertilization, incorrect pruning and the like. The discoveries 

 set down in his "Natural History" contain much worthy of notice regarding 

 the influence of atmospheric factors, cultural mistakes, circumstances pre- 

 disposing to disease etc. 



In the edition of the "Romischen Prosaiker" by Osiander and Schwab, 

 the translator of PHny (Kiilb) has given a summary of Pliny's sources and 

 special remarks on the authors instanced in his "Natural History." There 

 is rich material here for a complete history of phytopathology. We must 

 content ourselves with a reference to these carefully collected Greek and 

 Roman sources and perhaps show by only a fev/ more quotations what exten- 

 sive discoveries had been made at the beginning of our era. According to this, 

 there may be found in the seventeenth book of Pliny's "Natural History," 

 Part XXXVII., his statement of the action of frost. He says, "Not the weak- 

 est trees are endangered by frost, but the largest ones, and, therefore, when 

 they do sufifer, the highest tips become blasted, because the sap arrested by 

 the cold can not reach that point." We find the following note about the 

 phenomena, which we would now call "frost blight," — "The evil influence of 

 the stars depends entirely on the Heavens ; on this account there must also be 

 included among these efl^ects, hail as well as blight and the injury 

 caused by white frost. The blight especially attacks tender plants if, enticed 

 by the warmth of spring, they venture to break through the ground and it 

 singes the juicy buds of germinating plants. In blossoms this is called 

 blasting." 



In regard to carefully cultivated grape vines, one reads — "Another bad 

 influence of the stars (atmospheric factors) is the covering with dew 



Plinii Secundi naturalis Historiae libri XXXVII edit. Janus. Book 17, Chap. 37. 



