552 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



phoriis. It was at once evident and certain that they were distinct 

 fungi. Although the spore measurements varied considerably 

 when the fungus was grown on different media, yet, on the whole, 

 it agreed well with Spondylocladium atrovirens Harz. Careful 

 studies of the fungus Phellomyces sclerotiophorus revealed some 

 very interesting things. It was found that while the fungus 

 produced an abundance of sclerotia which are plainly visible to 

 the naked eye, yet under the microscope they are seen to be 

 provided with setae (fig. 19). These setae were first thought to 

 be abortive conidiophorcs of Spondylocladium atrovirens. How- 

 ever, further studies showed hyaline one-celled spores, sparingly 

 formed, in typical acervuli but not on the sclerotia (figs. 20 and 

 21). This would place the fungus in the genus Colletotrichum. 



It may be contended that the fungus Phellomyces sclerotiophorus 

 was not pure and that in our culture it was merely contaminated. 

 In order to settle this, dilution cultures of the spores were made. 

 In three to eight days, typical colonies of the Colletotrichum sclero- 

 tium-producing fungus appeared (figs. 7 and 9). In manner of 

 growth, these isolation colonies were identical with the sclerotium- 

 producing fungus obtained from the spots of silver scurf of the 

 white potato (figs. 8 and 10). Cultural work carried out in the 

 fall of 1914 and 191 5 duplicated the results obtained the previous 

 year. This proved conclusively that Spondylocladiw7i atrovirens 

 was in no way connected with Phellomyces sclerotiophorus, and 

 that the genus Phellomyces was not valid. Recently O'Gara (25) 

 described a new species of Colletotrichum which he isolated from 

 portions of underground stems of the white potato, and which 

 he named C. sola?iicolum O'Gara. Dr. O'Gara was kind enough 

 to send me a pure culture of his new Colletotrichum as well as 

 sectioned and stained slides of the fungus, as it appears natural 

 on the host and in pure culture. The writer observed at once 

 the resemblance of Dr. O'Gara's Colletotrichum to the Colleto- 

 trichum-Vike fungus isolated from silver scurf spots. Cultures of 

 our strain were submitted to Dr. O'Gara, who pronounced it the 

 same or similar to his new Colletotrichum solanicolum. • 



It will be remembered that Frank (5), in describing Phellomyces 

 sclerotiophorus did not carry out pure cultures of his new genus 

 and species. It should further be added that the sclerotia on the 

 living host often fail to produce setae, and that in pure culture 



