54 



tions in the center of the coiiceptacles or PerWiecia of the fungus ; 4, a 

 longitudinal section of the black-knot and branch of a cherry tree, in 

 which sections of the Perithccia are exhibited highly magnified, while 

 the woody fiber is represented of the natural size, as seen by the naked 

 eye; in its advanced stages its woody structure appears as if it had 

 been broken np into shreds or burst asunder, and its interstices filled 

 with a ver}' porous bark-like substance, which is again interspersed with 

 a very tine transparent thread-like mycelium ; I have no evidence, how- 

 ever, that this mycelium lias any direct relation to the black-knot fun- 

 gus ; 5, a typical representation of the Perithecia ; 6, a very highly mag- 

 nified transparent view of a Perithecium. The structure is cellular as 

 exhibited, and of a dark amber color. Each top surface-cell of the Per- 

 ithecia generally contains two or more very minute spore-like bodies ; 

 frequently the bottom cell of the mycelium contains these spores also. 

 Perfected fruit will doubtless yet be found on the mycelium, which is joint- 

 ed and branched, and resembles verj' much in structure the fruited black- 

 orange mycelium, described in my last report, except in color. I have 

 found floating in the gum solution, when examining the mj'celium of 

 the black-knot, several Perithecia without stalks having the same color 

 as the mycelium ; but further observations are necessary to demonstrate 

 their relationship. Further investigations will have to be made before 

 •any suggestions can be published in relation to the prevention of black- 

 knot as a result of the work already prosecuted. 



Onton-rust. — In a recent experiment, made for the purpose of de- 

 stroying fungus on the onion, the following mode has proved very suc- 

 cessful : Some specimens were obtained in the market, covered with 

 amber-colored fungus. 1 secured one of them in an inverted glass 

 receiver, wliich 1 placed over a beaker filled with nitrous acid". The 

 fumes arising from the acid, without the application of heat, enveloped 

 the onion, and soon dissolved and destroyed the fungus covering its 

 surface. In order to ascertain whether the life of the plant had been 

 destroyed, I placed it in a bulb-glass filled with water. It sprouted in 

 a few days, and is now in htailthy growth on my desk. It has numer- 

 ous leaves, which have attained a length of (3 to 12 inches ; thus show- 

 ing conclusively that, in some cases, fungoid growths may be eftectually 

 destroyed without injury to the plants on which they grow. 



This principle admits of many important applications. In some dis- 

 eases of the potato the surface alone appears to be affected, and the 

 same is true in regard to certain diseases affecting the tubers, roots, 

 fruits, and grains of various other plants, any of which may be readily 

 exposed in large quantities to the fumes of nitrous acid. As nitrous 

 iicid has the power of depriving organic bodies of their oxygen, its 

 destructive action on fungus is probably due to this property. The 

 extent to which this treatment may be safely applied to the vsmaller 

 grains will be tlie subject of future experunent. 



THE PHYLLOXERA IN AMERICA. 



It is known that M. Planchon, a distinguished scientist, was delegated 

 by the Agricultural Society of Herault, in France, to visit the United 

 States during the last summer for the purpose of investigating the 

 character and habits of the insect which has for several yeans past been 

 so terriblv destructive to the vineyards of Europe, and the ravages of 



