ccxv 



June 5, 1876. 



C. V. Riley, President, in the chair. 



Twelve members present. 



The Corresponding Secretary read a letter from Prof. Hinrichs, 

 of Iowa State University, acknowledging his election as Corre- 

 sponding Member, and presented to the Academy 19 pamphlet 

 publications of Prof. Hinrichs. 



Dr. Geo. Engelmann read the following communication on 

 certain fungi of the Grape and Oak, specimens of which were laid 

 before the Academy : 



OAK AND GRAPE FUNGI. 



Some fifteen years ago I presented to the Academy an account, with 

 microscopic drawings, of two of the most destructive fungi of our grape- 

 vines. One of them is the "Mildew," a downy white coating on the under- 

 derside of the leaves, the peduncles of the just forming fruit and the very 

 young berries themselves causing the leaves to wither and the young fruit 

 to shrivel and fall ofi". That fungus was classed as Botrytis, and is now 

 known as one of the PeronosporcB, another one of which constitutes the 

 potato disease. This appear? at the time of flowering or soon afterwards. 



The second, and, I believe, more common and more destructive fungus, 

 attacks the full-grown, yet green berries, and destroys them. After pene- 

 trating the tissue with its mycelium, it appears on the surface of the berry 

 as a minute discolored spot, always on the side, which enlarges, and pro- 

 duces black pustules visible to the naked eye, which at last kill the berry 

 and cause it to dry up, emitting at the same time their millions of spores. 

 This fungus, described as Pkoma viticola, makes its appearance in the 

 latter part of July and in August. 



I exhibit to you, to-day, another grape fungus which is new to me, and 

 seems to have been unknown to those grape growers with whom I have 

 conversed. A yellowish-brown spot, a few lines in diameter, appears on 

 the leaf, on the upper side of which a good eye, or a glass, will discover a 

 number of very minute black specks. These are little globules, 0.13-0.15 

 line in diameter, which have a little opening at the top from which they 

 emit their microscopical spores by the thousand. These oblong or oval 

 spores are one-celled, and have a diameter of 0.013 or 0.014 line. 



This fungus belongs to the family of Coniomycetes, and to that group 

 which live on decaying vegetable matter. Those yellow spots are the de- 

 caying substance, but their vitality has been destroyed by the mycelium of 

 the fungus ; those still more minute threads which penetrate the tissue in 

 every direction, exhaust and kill it, and thus form what we may call their 

 fruit, the perithecia, which when mature emit the spores. It belongs to the 

 genus Depazea, of which many species, mostly leaf-inhabiting, are de- 

 scribed and it may be called Depazca Labruscce — Grape-leaf Spot. 



