This parasite makes its appearance earlier than the others mentioned 

 above, viz., just before and during the flowering period, and attacks, as far 

 as known, only the leaves, which, where abundant, it kills, and thus crip- 

 ples the plant : it is also found, though rarely, on petioles and peduncles. 

 Dr. "Wislizenus informs me that it attacks indiscriminately all grape varie- 

 ties, but more the lower leaves of a stock than the upper ones ; while he 

 finds the Phylloxera galls on the uppermost not yet full grown foliage. 



I present to you another fungus, on oak-leaves, which show the same 

 yellow decayed spots; but here you have to look for the perithecium, the 

 fruit, if we maj- call it so, of the fungus, to the lower side of the leaf, and 

 it is not a black gobule as in the grape-leaf, but a brown elevation, little 

 darker than the surrounding spot. I find no pore at the top, but suppose 

 that it emits its spores through a rent. These are very different from the 

 spores of the Depazea, being elongated, usually curved and septate, or 

 forming three or four distinct compartments; the spores are a little longer 

 than those of the grape spots, the perithecium is twice as large as that of 

 the grape. 



The septate spores indicate that it belongs to the genus Septoria, and 

 the fungus may bear the name of Septoria querci. 



It is necessary to remind you, that, though we know a great many forms 

 of fungi, we know the life history of only a very few. It is certain of some, 

 and very probably of many, that they constitute transition states of other, 

 more highly developed fungi, and only when we shall have become ac- 

 quainted with the different phases of their development shall we be able 

 to appreciate their importance and counteract perhaps their destructive 

 action. 



Mr. Riley remarked on the above communication, that, with 

 regard to Peronospora viticola, according to his experience, it 

 came much later in the season, and did not attack the fruit ; and 

 cited as corroborative a recent paper by Prof. W. G. Fallow, 

 published in the Bulletin of the Bussey Institution, where the 

 ground is taken that by shriveling up the leaves, and permitting 

 the fruit to ripen, the fungus is actually beneficial. This singular 

 opinion of Prof. Farlow may hold good in the more Northern 

 States, where the fungus is only moderately abundant ; but in this 

 latitude the fungus has just the contrary effect, and, by prematurely 

 robbing the vine of its leaves, prevents the maturing of the fruit. 

 Acres of Delaware failed to ripen fruit from this cause last year. 



The fungus, described as Defazea Labruscce, suddenly ap- 

 peared after the few cold days that succeeded unusually warm 

 weather toward the end of May. It did most injury by attacking 

 the petioles and peduncles, making thereon darker spots than 

 on the leaves, and often cauterizing the parts. As suggested by 



