PiiTHYBEiDGE — Experiments with Phijtophthora. 27 



discussed, little harm would be done. But where matter of tliis kind is 

 incorporated as established beyond doubt into text-books written for the 

 information of students and others, the case becomes more serious, owing to 

 tlie danger of non-critical readers being misled. 



There is no evidence at prasA"! existing to show that the attack of the 

 potato-crop as a whole with blight occurs otherwise than by aerially borne 

 " spores," if we except the few diseased plants from diseased tubers which 

 do undoubtedly occasionally occur, but wliich can scarcely be regarded as 

 being part of the general crop. Whether the sources of these " spores " at 

 present known are sufficient to account for the annual recurrence of the 

 blight, and particularly for the time of its appearance each year, are questions 

 which must be left for future work to decide. 



Bibliography. 



1. Pringshhim, N. — Ueber die Kartoffelkrankheit. Vierter Bericht d. 



Ceutralkommission f. d. agrikultur-chem. Versuchswesen. Land- 

 wirthschaftl. Jahrb., Bd. 5, 1876. 



2. Smith, Wokthington, Gr. — Diseases of Field and Grarden Crops, 



London, 1884, pp. 295 et seq. 



3. [Board of Agriculture]. — Report on recent experiments in checking 



Potato Disease in the United Kingdom and abroad. London, 

 1892, p. 56. 



4. Massee, Gr.— a Text Book of Fungi.— London, 1906, p. 210. 



5. Perpetuation of " Potato Disease " and Potato " Leaf Curl " by 



means of hybernating mycelium. Kew Bulletin, No. 4, 1906, 

 p. 116. Reprinted in Journ. Bd. Agric, vol. xiii., 1906, p. 233. 



6. Anonymous, — The spread of fungus diseases by means of hybernating 



mycelium. Journ. Bd. Agric, vol. xiii., 1906, p. 257. 



7. Massee, Gr. — Diseases of cultivated plants and trees. London, 1910, 



p. 125. 



SCIENT. PROU. K.U.S., VOL. XIU., NO. II. 



