DISEASE OF THE VINE. 241 



decomposed cells of the epidermis. It is therefore most natural 

 that the filaments in lengthening should follow the direction of 

 spots where they find -a nutritive fluid. This fluid must be in an 

 exceedingly ininute quantity, for when the Grape bursts, the 

 fungus never spreads or penetrates into the interior, where it 

 might be supposed to find in greater abundance, and to absorb 

 more readily, the fluids it requires. 



As I have mentioned the bursting, the final destruction of the 

 Grape, I will add the manner in which I account for it. In the 

 circular field of the microscope, I counted up the number of 

 angular cells on the surface of the portion of the epidermis 

 comprised within it. Having subjected to the same test green 

 and ripe grapes of various sizes, I always found that the number 

 of cells contained in the same visible surface corresponded very 

 nearly in an inverse ratio to the squares of the diameter of the 

 Grape. From this I conclude that the Grape in enlarging in size 

 does not increase the number of its cellules, but that these are 

 distended in proportion. Now if by the effect of the disease or 

 from any other cause, the cellulose, as it happens in this case, 

 loses its life and consequently the faculty of distending, it is 

 evident that the growth of the internal unaffected parts would 

 cause a pressure, and force the epidermis to burst. 



I will not enlarge further on this disease of the Vine. This 

 subject, deserving the most serious study, cannot be better 

 investigated than by your commission, which has been charged 

 to collect all facts and reports relating to it, to which commission 

 the illustrious President Marchese Ridolfi* has done me the 

 honour to associate me, together w r ith my colleague the Cavaliere 

 Parlatore. By connecting our different observations and re- 

 searches, and discussing the subject together, we may possibly 

 attain the object which the Academy is desirous of reaching. 



My Memoir was already in print when I received a letter 

 which Professor Savi has done me the honour to address to me. 

 T rejoice in being yet in time to publish it here : — 



To MY COLLEAGUE, PROFESSOR GlO. BaTTISTA AmICI. 



I must, in the first place, thank you for the politeness 

 with which you have been pleased to enable me to repeat your 

 observations on the cryptogam now devastating our Vines, which, 

 by a singular and fortunate combination, has manifested itself to 



