USTILAGO. 281 



Knowles/ Cugini,^ and Wakker^ have investigated the 

 anatomical changes produced by this fungus. The latter 

 investigator found that the xylem -elements with unlignified 

 walls remain incompletely developed, and have a peculiarly 

 twisted course ; that normal sieve-tubes are absent ; that the 

 cells of parenchyma undergo secondary division, and give rise 

 to a new tissue, provided with little fibrovascular bundles, and 

 rich in starch-contents, in other words, a nutritive tissue to be 

 used up in the spore-formation of the smut. 



The disease may be found wherever maize is cultivated, 

 and often causes a very serious diminution in the harvest. 

 It may be combated by early removal and destruction of the 

 smut-galls. As a preventive measure, the treatment of seed-corn 

 with copper sulphate solution* is recommended. The avoidance 

 of fresh manure is also advisable, since conidia capable of germi- 

 nation may be lodged in it. 



The following are the results of an experiment carried out 

 at my instigation by Professor Wollny in his experimental 

 plots at Munich. Three plots were selected distant from each 

 other about 70 metres. On 2nd May, 1893, these were marked 

 out in rows 40 centimetres apart, in which maize was sown at 

 intervals of 50 cm. The grain was previously mixed with 

 smut-spores obtained from the Tyiol in autumn, 1892. Plot 

 No. 1 was left without manure. No. 2 was treated with old. 

 No. 3 with fresh cow-manure. Maize had never been grown 

 in the vicinity, so that no infection could result from external 

 sources. The results were : 



Ustilago Schweinitzii Tnl. from Carolina U.S.A. is probably identical 

 with Ust. maydis. 



Ust. Fischeri Pass.^ This smut, observed in upper Italy, 



iKnowles, E. J., Amer. Journal of Mycology, Vol. iv., 1889. 

 ^Cugini, "II carbone del grano turco," .SoK. dell. stat. Agrar. di Modsiia, 1891. 

 ^Wakker, Pringsheim's Jahrbuch, Bd. 24, 1892. 



^See "General Part," chap, vi., and also " Vergleichende XJntersuuhungen 

 lib. Flugbrandarten." P. Herzberg in Zopf's Beitrdgen, 1895. 

 ^Passerini, Just's botan. Jahrbuch, 1889, p. 123. 



