1857.] Tie Mildew and iJie Rot in tJie Grape. 499 



the white pine of our forest. The branches when full grown are 

 numerously subdivided and beset with myriads of mycroscopic spores, 

 or germs, which are readily detached by the wind and fill the air 

 with invisible but reproductive elements. 



The malady well known among cultivators as the black rot, and 

 which has proved even more destructive to the grape than the mil- 

 dew, makes its appearance at a later period, and in a more insidious 

 manner, in the form of a black speck on the surface of the berry 

 which sometimes is quite limited, but oftener spreading and soon in- 

 volving the whole berry in its destructive grasp. This disease has 

 always succeeded the mildew, but has more frequently made its 

 appearance in our vineyards, without that sure precurser, rapidly 

 spreading, and often destroying almost the entire crop, especially 

 in unfavorable locations. This appears to be produced b^' the same, 

 or another species of fungus at a later period, after the cuticle has 

 become so much thickened and condensed as not to allow the ready 

 attachment of the spores, and growth of the fungus upon the sur- 

 face, but may here be seen in the form of a white thread-like mycel- 

 ium in the interior of the berry, interwoven among the cells, which 

 in consequence soon become disorganized and broken down, first be- 

 coming brown, then black, and either fall off or dry up and remain 

 attached to the stems. 



The presence of this internal fungus is generally indicated by a 

 bluish tint on the surface of the grape, the destruction of which is 

 sure to follow ; in many cases this fungus may be seen filling up and 

 growing out of the stomates, or breathing pores of the stems, and 

 pedicels of the fruit, and if the pedicel be divided lougituclinally, 

 with a sharp knife, these white thread-like fibers may be seen under 

 the microscope, running among the cells quite into the berry itself, 

 and its effects are equally fatal whether in the stem or the fruit. 



The source from whence the spores or germs, of these fungi orig- 

 inate is at present involved in obscurity, and may long remain a sub- 

 ject of conjecture and speculation. They are probably floating in 

 the atmosphere like the germs of the fermenting fungus which when 

 admitted in contact with the transparent filtered juice of ripe grapes 

 has been known to commence its growth in one hour after being 

 pressed, rendering the fluid cloudy and thick, and giving off bubbles 

 of gas, and in three hours to form a considerable layer of a greyish 

 yellow substance on the surface called yeast. This substance when 



