686 SUMMARY OF CURBENT RESEARCHES RELATING TO 



parasitic on the cucumber, causing rapid destruction of previously 

 sound leaves, which turn entirely yellow from the apex downwards, at 

 length completely destroying the plant. The hymenium is abundantly 

 produced on the surface, where the mycelium has completely permeated 

 the tissue of the host. 



Exoascus of the Cherry.* — Following out Eathay's observations 

 on Exoascus Wiesneri,'\ which he considers identical with E. cerasi 

 rkl., D. Kutsomitopulos states that in all the cases where the cherry 

 is attacked by the malformation known as " witch-broom," all the 

 branches arc plentifully permeated with the mycelium of the parasite. 

 This is the case even in the inflorescence, which seldom reaches 

 maturity ; it could be traced in the pedicels, calyx, stamens, ovary, and 

 style, permeating the parenchymatous fundamental tissue, but without 

 any perceptible effect on the organs, the petals only seeming to be 

 completely free from it. In the infected wood the author found the 

 medullary rays to be from 4 to 8 cells wide, and each about 66 /a 

 in diameter, while in the healthy wood the rays are only 2 cells wide, 

 and each only 27 /x on an average in diameter. The woody bundles 

 of the sound part are about 60 fj. wide, and contain no parenchyma, 

 while those of the diseased part average about 30 /x in diameter, and 

 contain much parenchyma in addition to the fibrovascular bundles. 

 These facts account for the much greater looseness of the tissue of the 

 diseased portions of the wood. 



Hyacinth-diseases.J — J- H. Wakker has investigated the "yellow 

 disease " to which hyacinths are subject. An examination of infected 

 bulbs in the autumn shows that the vascular bundles are permeated or 

 even replaced by a yellow slime, in which are immense quantities of a 

 bacteriimi which he proposes to call Bacterium Hyacinthi, very closely 

 resembling B. Termo. While imbedded in the slime it is motionless, 

 but when removed soon commences a lively motion, and begins to 

 divide. In the spring the same slime thronged with bacteria is found 

 in the vascular bundles of the leaves. 



The " black smut " (^der schwarze Botz) of hyacinths is due to the 

 attacks of an ascomycetous fungus closely resembling Peziza ciborioides 

 Fr., parasitic on clover, the sclerotia of which are found in the under- 

 ground parts, from which the aerial parts, with the asci, can be 

 developed by placing the diseased bulbs in a pot and copiously 

 watering. 



Identity of Oidium monosporium "West, Peronospora obliqua 

 Cooke, and Ramularia obovata Fkl. § — C. A. J. A. Oudemans 

 clearly identifies these fungi, described as three distinct species. 

 Rejecting the inappropriate specific name "monosporium," and 

 adopting that of Cooke, the author proposes to call the fungus 

 Ovularia obliqua, being clearly distinguished from Peronospora by its 

 much-septated hyphae. 



* SB. Phys.-med. Soc. Erlangen, 1882. See Bot. Centralbl., xiii. (1883) 

 p. 373. 



t See this Journal, iii. (1880) p. 835. 

 X Bot. Centralbl., xiv. (1883) pp. 315-7. 

 I Hedwigia, xxii. (1883) pp. 81-6. 



