THE VlNE-MlLDEW. 2?1 



visible in the still closed fruit, although they were already 

 present, as was demonstrated by the ruptured sporangium after 

 the escape of the spores. The process of the formation of these 

 spores, and of the cells, did not come under observation. The 

 form and size of the spores is by no means constant ; sometimes 

 they are oval, sometimes more cylindrical, sometimes straight, 

 sometimes curved, and their major axis, which on an average 

 equals -g-t-^ of a line, sometimes is as little as -j-^-g- line, while it 

 occasionally reaches —5- ^^^Q- A little nucleoid dot as observed 

 by Amici exists at either extremity, the size of which is too 

 minute to admit of any investigation of its nature. 



Globose fruit also occurs but rarely, devoid of hairs, and similar 

 to the intermediate form described in the Hop-mould. 



Unfortunately I was not able, though with a lens in my hand I 

 searched through many a vineyard, to discover the Erysiphoid 

 fruit ; everyone, however, will be convinced from the perfect 

 resemblance which the Vine-mildew exhibits in every other 

 respect to Erysiphe, that under favourable circumstances this 

 form also must be developed. So long as this remains undis- 

 covered, we must postpone the assignment of the plant to a 

 distinct genus, the formation of a diagnostic character, and tlio 

 establishment of a name. 



Are then the bodies in the Cicinoboloid fruit spores capable of 

 germination ? To this I can make no distinct answer, since the 

 efforts to induce germination, which so readily succeed in the case 

 of the elliptic couidia, remain without any result. If, however, 

 this function belongs to them, as is not improbable, this disastrous 

 plant has a capability of propagation which is absolutely frightful. 

 Apart from the conidia, which perhaps possess the power of 

 propagation only during the summer, if 200 spores only be 

 reckoned to each fruit, and on each square line of the surface of a 

 berry only 100 fruit, which in moderately- fertile individuals is far 

 below the reality, a berry five lines in diameter would furnish 

 about ]^ million of spores,* and consequently we can form no 

 imagination of the quantity which even a small vineyard would 

 afford. 



How do the spores pass the winter '? Probably on the earth, 

 where they are cai'ried by the rain which dissolves the cirrhi. If 

 we reflect that the same mode of fructification belongs to the 



* This quantity may at first sight seem excessive, but if we reflect ou 

 the dimensions given above, from accurate admeasurement with a screw 

 micrometer, v/e shall find that it requires 27 millions to cover a square inch. 



