ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 129 



disease is propagated, the ejection taking place in wet weather only. 

 Gnomonia furnishes another example of sexual reproduction among the 

 Pyrenomycetes, the author having distinctly observed the production of the 

 perithecia as the result of the impregnation of a trichogyne by spermatia 

 in the same way as in Polysiigma. The spermogonia are formed in the 

 spongy parenchyma, the spermatia having the form, as in Polystigma, 

 of long slightly curved threads. Several spermatia appear to impregnate 

 a single trichogyne. The spores germinate at once, perforate the cuticle, 

 and, penetrating the epidermal layer of cells, develope into a mycelium 

 in the intercellular spaces of the mesophyll. By the infected leaves 

 remaining on the trees after being killed by the fungus, the spread 

 of the parasite is greatly promoted. 



Orange-leaf Scab.* — Mr. F. L. Scribner describes the above disease, 

 and suggests various remedies for arresting the malady. It first makes its 

 appearance as small wart-like excrescences on the upper or under side of 

 the orange-leaves. These excrescences increase in number and size, until 

 the whole surface is covered, the vitality of the leaf becoming destroyed. 

 Upon some of the diseased specimens there was discovered a species of 

 Fusarium, believed to be identical with F. sareochroum Desm., the tubercles 

 being apparently caused by the mycelium of this fungus. The hyphse and 

 spores are present in greater or less abundance on all the more developed 

 excrescences. 



Peronospora viticola.f — Dr. P. Baccarini describes a peculiar disease 

 which has recently attacked vineyards in the south of France, known as 

 " negrone " or " negrara," and manifested in the drying up of the berries 

 which still remain attached to their stalks. He attributes the malady to 

 a peculiar development of Peronospora viticola and not, as has been generally 

 supposed, to the attacks of the American " black-rot," PJioma uvicola. 



Mode of Destruction of the Potato by Peronospora infestans.| — Mr. 

 E. W. Claypole states that in a potato the vascular layer appears as a 

 semi-transparent line running along the cut surface about 1/4 in. below the 

 cuticle, and rising to the eyes where it meets the layer that represents the 

 bark. At these points the cuticle is exceedingly thin, and here the assault 

 of P. infestans is usually made. Its progress is marked by a black streak 

 advancing from the eye along the layer of vascular tissue. A layer of the 

 bark immediately under the rind is attacked in the same manner. In these 

 two layers the life of the potato resides, and their destruction consequently 

 insures its death. 



"Black-rot" of the ■Vine.§ — MM. P. Viala and L. Eavaz describe a 

 disease which has attacked vineyards in France since 1885, and which is 

 identical with the American " black-rot " produced by Phoma uvicola. It 

 attacks both the leaves and the berries, causing the latter to dry up and the 

 skin to become covered with numerous pustules. These are produced by 

 the conceptacles of the fungus, which are of two kinds ; the larger are 

 pycnidia containing stylospores, the smaller spermogones containing slender 

 spermatia. While the "black-rot" is due exclusively to the attacks of 

 Phoma uvicola, the diseases known in America as " grey-rot," " common- 

 rot," " soft-rot," and " brown-rot " are all caused by Peronospora viticola. 

 " Black-rot " has nothing to do with anthracnose, the identification of 



* Bull. Torrey Bot. Club, xiii. (1886) pp. 181-3. 



f Malpighia, i. (1886) pp. 56-60. % Ball. Torrey Bot. Club, xiii. (1886) p. 191. 



§ Viala, P., et L. Eavaz, ' Mem. sur une nouv. maladie de la vigne,' i pis., Mont- 

 pellier, 1886. See Bull. Soc. Bot. France, viii. (1886) Kev. Bibl., p. 129. 



1887. K 



