748 



SCIENCE 



[N. S. Vol. XXXI. No. 802 



attempt to discover whether similar phenomena 

 occur in the smuts. It also aimed to find the 

 relationship of the group from their finer struc- 

 ture. 



It has been found that the mature teleutospore 

 of all smuts is uninucleated, but that there are 

 two nuclei in the younger one in the TiUetiacese 

 and possibly so in the Ustilaginaceae. The my- 

 •celium of. the former group shows many binu- 

 cleated cells, like the rusts, but in the latter 

 group it is multinucleated. This would seem to 

 indicate that the smuts of the Tilletia group are 

 more nearly related to the rusts than those of 

 the Vstilago group. 



The complete life history of the oat smut ( U. 

 levis) was traced. It was found that the pro- 

 mycelial cells were uninucleated, the conidia uni- 

 nucleated, but that they became multinucleated 

 immediately after putting out a germ-tube. In- 

 fection occurred in three to five days and the 

 entire tip of the seedling was full of the inter- 

 cellular mycelium. The entire mycelium breaks 

 up into spores at the time when the rudiments 

 of the flowers appear. 



Life History of Melanops quercuum (Sohw.) Rehm 



forma vitis Sacc: Dr. C. L. Shear, Bureau of 



Plant Industry. 



The fungus under consideration has had a great 

 variety of names applied to it in its different 

 stages. The ascogenous stage is best known in 

 Europe under the name Botryospharia Berengeri- 

 <ma de Not. In America it has been frequently 

 •called Botryosphwria fuliginosa (M. &N. ) E. & E. 



Various surmises have been made as to the 

 pycnidial form of this fungus, but all have here- 

 tofore been based upon the close association of 

 perithecia and pycnidia on the same specimen. 



Pure cultures made from carefully isolated 

 single ascospores have produced pycnidia which 

 at first discharged hyaline, non-septate spores of 

 the Macrophoma or Dothiorella type. Later the 

 spores borne in the pycnidia became brown and 

 many of them uniseptate, corresponding exactly 

 with Sphceropsis viticola Pass and S. Peckiana 

 Thiim, whicn were also found associated with the 

 perithecia on the specimen from which the cul- 

 tures were made. They also agree in all morpho- 

 logical characters with Sphceropsis malorum Peck 

 and Diplodia pseudo-diplodia Fckl. The ascogenous 

 stage is frequently found on the apple and a great 

 variety of other trees and shrubs and has generally 

 been regarded by mycologists as one and the same 

 species, though Saccardo treats some of the speci- 

 mens on different hosts as forms. In a few cases 



another form of pycnospore was found in the 

 same pycnidium with the Sphceropsis spores, the 

 sporophores being intermingled and clearly arising 

 side by side from the wall of the pycnidium. These 

 spores were small, hyaline, cylindrical and 2-3 X 

 1 fi. These were found on the hosts and not in 

 the cultures. The fungus is not known at present 

 to cause any serious injury to the grape, but the 

 form on the apple causes the well-known " black 

 rot," leaf spot and canker. 

 The Chestnut Bark Disease: Dr. Haven Metcalf 



and Professor J. Fbanklin Collins, Bureau 



of Plant Industry. 



The active parasitism of Diaporthe parasitica 

 Murrill has been verified by nearly five hundred 

 successful inoculations. Lesions may occur on 

 any or all parts of a tree above ground, and may 

 girdle anywhere. Most common places are 

 crotches, base of trunk, and ultimate twigs. 

 Roots and first-year wood are rarely, if ever, 

 attacked. Sprouts are regularly formed below 

 girdled points. Inoculations may take effect at 

 any time of year, but the progress of the disease 

 is most rapid in the spring months. A debilitated 

 tree is no more subject to attack than a healthy 

 one. Dry weather checks the disease by sup- 

 pressing spore production. The parasite can enter 

 without visible breaks in the bark, but wounds 

 form the usual means of entrance. Of these the 

 commonest are tunnels of bark borers. Winter 

 injury is not common over the whole range of the 

 bark disease, but may be locally important in 

 producing lesions through which the parasite 

 enters. Winter injury bears no other relation to 

 the bark disease. The presence of Diaportlie para- 

 sitica Murrill forms a sure basis for distinguish- 

 ing whether any given case is the bark disease or 

 winter injury alone. The bark disease shows no 

 definite relation to the points of the compass, the 

 position of lesions being determined by the posi- 

 tion of the wounds through which the fungus 

 gained entrance. The present range of the bark 

 disease is from Saratoga County, N. Y., and Suf- 

 folk County, Mass., on the north and east, to 

 Bedford County, Va., on the south, and Green- 

 briar and Preston Counties, W. Va., and West- 

 moreland County, Pa., on the west. 

 Bacillus phytophthorus Appel: Dr. Eewin F. 

 Smith, Department of Agriculture. 

 We owe the name and our first accurate in- 

 formation respecting this organism to Dr. Otto 

 Appel, of Berlin. The following statements are 

 the result of three years of study of this bacillus, 

 cultures of which were received by me from Berlin 



