DISEASES OF PLANTS. . 469 



A''/. /, /'/'. I''>7, /'!S, Ji(/x. .J). — A report is given of ;i disease wliicli attackeil and 

 destroyeii many y< unit: ]»ine and spruee seedlings which were growing in pots. The 

 fungns cansing tin- tn>nl>lc was isolated and cnltivated. Inoenlation e.xi)eriinents 

 wt're condncted and it was found that a species of Fusoma, which is as yet nndeter- 

 mined, was the cause of the disease. 



Infection experiments with .fficidium strobilinum, ('. von TruKiyK [Arh. K. 

 (ii'siiii<llicils(iiiitc, Biol. AliL, J {1901), Xo. 1, pp. 164-107, _1i(jx. .>) . — A report is given 

 of inoculation experiments with the jccidial si)ores taken from cones of a spruce, 

 upon I'ici'd e.m'lxd, I'riuiiin pndn.'<, various species of Campanula, Betula, lOpilohiuni, 

 Tussilago, and Carex, and upon tSalij: purpurea, >S. caprea, and Sorbwn aucupurUi. 

 The infections were successful only upon Prnnus padus, upon tlie leaves of which 

 uredo- and teleutospores were formed^^ showing that the alternate generations of this 

 fungus were spent upon the spruce and this species of Prunus. 



Infection experiments -with the rust of white pine, C. von Tuhkui'' {Arh. K. 

 (u'simdhriLviiiitc, Biol. Aht., J {1901), No. 1, pp. 173-175). — An account is given of a 

 numher of experiments conducted Ijy the author and others, in which the relation- 

 ship between iVr/f/r'/VA(m;y< .sfroZ/i, the rust of the white pine, and that occurring on 

 various species of Ribes, is shown by inoculation experiments. 



Concerning Tuberculina maxima, a parasite of the leaf rust of w^hite pine, 

 C. VON Ti-HKi-F {Arl>. K. <hxiiii<llu'it>i(tmti', Biol. Ahf., J {1901), Xo. 1, pp. 1H9~173). — 

 A brief review is given of the literature of the genus Tuberculina, and the systematic 

 position of T. mariiixi, a j»arasite of the rust fungus of white pine, is discussed. 



Infection experiments with Gymnosporangium juniperinum from the 

 leaves of Juniperus communis, C von Tubeuf {Arb. K. Gentiwllwitxcuutc, Biol. Aht., 

 2 {1901), No. 1, }>p.l77, 17S). — Infection experiments upon a number of i)lants are 

 rei)orted, in which it was shown that the Rrestelia stage of Gymnosporangium jimi- 

 jH'ri)iu)n occurs on Sorhus avcujxtria and upon Amelanchier rotundifolia; and the same 

 stage of <him)Kj!<poran(jiimi tremelloides is found upon Fijnu inalus, Sorhun aria, and *S'. 

 cliainxnii.'ipihof. 



Further investigations on the abnormal outgrowi;hs of Hibiscus vitifolius, 

 Elizabeth Dale {Bot. ('cnihL, ^5 {1901), No. 11, pp. S72-37o). — Experiments were 

 undertaken to determine the cause of the formation of outgrowths upon this jilant. 

 The outgrowths consisted chiefly of greatly enlarged epidermal cells, with very thin 

 walls. Sometimes the underlying parenchyma was also affected. The cells con- 

 cerned were always in the immediate vicinity of stomata so that the guard cells were 

 lifted up as the outgrowth developed. Experiments were conducted to test the 

 effect of moisture, temperature, and light in favoring the growth of these swellings. 

 Most of the experiments were made in the open air, as the occurrence of the out- 

 growths is very common on plants growing in greenhouses. Various combinations 

 of dry and damp air, and soil, were investigated, with the result that outgrowths 

 were always formed in damp air, provided there was sufficient light and heat, while 

 damp soil had no effect. The effect of light upon their production showed that' out- 

 growths were developed upon plants under clear glass, and under red and yellow 

 glass, but not under blue or green glass, in i)oor light, or in darkness. The forma- 

 tion of outgrowths was found to ])e favored by increased temperature, when the 

 other nece.ssary conditions were favorable. The innnediate effect of damp atmos- 

 phere is to check transpiration, and the swellings were only produced where trans- 

 piration was reduced. They occur only in plants in which there is an accumulation 

 of starch. The formation of the outgrowths was accompanied by the produi-tion of 

 oil, not found in normal leaves. It is considered probable that these outgrowths are 

 due to the local accumulation of osmotically active substances produced under abnor- 

 mal conditions, such as redu(!ed transpiration, and consequent lack of minerals, while 

 carl )oh yd rates are developed in excess. In addition to the experiments made upon 

 the Hibiscus, similar observations were made upon Jpoma:a woodii. 



