THE AMERICAK MONTHLY 



[January, 



Thomas Taylor, Microscopist of the 

 Department of Agriculture, read a 

 paper relating to the moi"phology of 

 the fungus known to botanists as Oidi- 

 um Tuckeri. He said : This fun- 

 gus was first observed in England as 

 a mildew on the foliage of the Euro- 

 pean grape-vine by a gardener named 

 Tucker, but its form and place in bot- 

 any was first made known by the Rev. 

 M. J. Berkeley, of England. The 

 vineyards of France were soon after 

 invaded by this fungus ; from thence 

 the spores were distributed over Eu- 

 rope, destroying the vintage for a term 

 of years and causing serious financial 

 disaster to those engaged in grape 

 culture. 



At an early period of its history it 

 was observed by Mr. Berkeley that 

 the Oidium-ioxvix was but one of the 

 stages of the fruiting of this fungus, 

 and that its higher form of fruit was 

 probably an erysiphoid, but up to this 

 date, 1883, no erysiphoid has been 

 found on the vines of Europe, al- 

 though it is stated that a form of fruit 

 named pycnidia has been obsei-ved 

 growing on the same mycelium with 

 the Oidizim^ and fashioned somewhat 

 in its outward shape like the Oidium 

 but differing from it in bearing ovules 

 and sporidia. The mildew, as seen 

 on the foliage, consists of very minute, 

 interlacing, white threads, felted, joint- 

 ed, and branched, from which arise 

 pedicels or stalks, on which are borne 

 a series of oblong spores joined end 

 to end. The latter constitute the 

 Oidium. For many years past, and 

 prior to the discovery of the vine- 

 Oidium of Europe, a similar Oidium 

 bearing an erysiphoid form of fruit 

 was observed on the native vines of 

 this country, and has been described 

 at various times by Curtis, Howe, 

 Peck, Farlow, Berkeley, Cooke, and 

 others as an Uncinula spiralis. In 

 the year 1870 I first observed, on the 

 foliage of several native species of 

 vines growing on the grounds of the 

 Department of Agriculture, not only 

 the Oidiu?n-^or\n.i but also the higher 

 fruit Uncinula spiralis. I have not, 



thus far, observed pycnidia associated 

 with the so-called Oidium or grape- 

 vine disease of this country. During 

 the summer of 1870 I made an inves- 

 tigation of a mildew observed on the 

 foliage of the foreign vines cultivated 

 in"the hot-house of the Department of 

 Agriculture, and found it to consist 

 of mycelium (spawn) , bearing coni- 

 dial spores. On comparing this inil- 

 dev\^ and its Oidium spores with the 

 drawings of the vine- Oidium describ- 

 ed by Mr. Berkeley, I found the two 

 to be identical in structure. In the 

 fall of the same year I discovered also 

 on the foliage of these vines (one hun- 

 dred varieties in all) little dark specks 

 hardly perceptible to the naked eye, 

 but in great profusion. By the aid of 

 the microscope their true character 

 was at once discovered. One seemed 

 to me to be an Erysiphe., the other a 

 species of Uncinula spiralis., the lat- 

 ter resembling the highest stage of 

 fruit found on the American vines. 

 Subsequent observations, however, 

 demonstrated that the two forms ob- 

 served, belong to Ufzcimda spi- 

 ralis., although it is plain that the 

 cell-structure of the appendages of 

 the two forms seen, differ very much 

 from each other, and this, too, when 

 it is evident that both specimens are 

 equally matured. In this matter fur- 

 ther investigation is needed. 



In the year 1871 the same vines 

 were again affected with this fungus, 

 but since then the higher fruit, U?i- 

 cinula spiralis^ has not appeared on 

 these vines vmtil this year (1883), al- 

 though I have carefully watched for 

 it each year. The Oidiwm stage has 

 been seen more or less every year on 

 these vines since 1871. During the 

 early part of November of this year 

 I observed that these vines were again 

 covered, as in 1870 and 1871, with 

 the perithecia of Uncinula spiralis., 

 specimens of which have been for- 

 warded to several of the leading mi- 

 cologists of America ; specimens were 

 also sent to Cooke and Berkeley of 

 England. The last-named gentle- 

 man has taken marked interest in the 



