519 



In the fall of 1872 I selected several vine-leaves from the foreign 

 Department grapery, having on their surface patches of mildew inter- 

 mixed with ijerithscia of the Erysiplie Tuclceri. Having removed portions 

 of them, I placed them on glass slides and secured them in position with 

 gum-water, over which 1 placed a thin glass disk. While viewing them 

 under a power of about 100 diameters I applied pressure on the disk in 

 order to burst the perithecia. I used great care in my manipulation, but 

 failed to get sporangia out of them. I then laid the leaves aside until 

 November, 1871. In consideration of recent successful experiments on 

 perithecia of black-knot fungus, I resumed my experiments on those of 

 the foreign grape-vine mentioned. I removed a small portion of the 

 leaves procured in 1872, containing the perithecia, placed it in a capsule 

 and poured over it concentrated ammonia with the view of softening its 

 albuminoid matter. To another j)ortiou I added nitro-muriatic acid and 

 neutralized the acid by ammonia. This latter method has the advantage 

 of bleaching the perithecium, which is naturally opaque, but when par- 

 tially bleached is of a translucent Vandyke-brown color. Under either 

 treatment the perithecia become soft and pliable, and the proper degree 

 of pressure may be given during the operation while viewing them under 

 the microscope. In this way I have succeeded in bursting them and 

 forcing out their sporangia in perfect form. I had previously failed in 

 this experiment, probably for the reason tbat the sporangia had not 

 matured sufficiently, and in consequence of the thinness of their cell- 

 walls they burst with slight pressure, and a grumous mass was all that I 

 obtained. The sporangia of perithecia of Microsphwria are easily removed 

 and seem to bear more pressure without breaking the cell-walls of the 

 sporangia than those of the vine, judging from my experience thus far. 



During the last four years I have examined many hundreds of speci- 

 mens of the Oidium form of the vine fungus, but in no case have I seen 

 connected with them pycnidia, forms of a cell described and illustrated 

 by Professor Amice and Doctor Plomley, of Europe, and represented by 

 them as connected in some way with the Oidium. 1 am certain, how- 

 ever, that 1 have found in great profusion, during the summer and fall 

 of both 1871 and 1872, on the vines in our foreign grapery, the true 

 fruit or j)ereithecia of Eryseplie Tucker i. The Eev. M. J. Berkley says : 



It is true that tLe real sporangia of the vine mildew have not yet been observed. 

 * * * We do not doubt, therefore, that at some future period the true sporangia 

 may be found, and vre trust that the little parasite which has been of such unlooked- 

 for importance may still preserve the specific name originally assigned to it, in honor 

 of the meritorious cultivator who first observed it. * * " It may, therefore, be 

 named Erysiphe Tuckei'i, and the name of Oidium Tu-ckei'i should be rejected. 



When Professor Planchon visited this Department last year, I pre- 

 pared for him a microscope-slide containing specimens of the perithecia 

 of Erysiphe Tuclceri, taken from a foreign vine of the Department 

 grapery. 



Should the climatic condition of the summer and fall of 1875 prove 

 favorable for further investigation in this direction, I may be enabled to 

 define more clearly the habits of Erysiphe Tuckeri, on a knowledge of 

 which depends the proper remedies to be applied for its destruction and 

 the consequent protection of the vine. 



FACTS FROM OFFICIAL SOURCES. 



AGtRICultueal and polytechnic institutes. — Mr. Lowndes, of 

 Maryland, in January, 1874, introduced into the National House of 

 Representatives, " a bill to aid in establishing agricultural and poly- 



