412 FIRST FORMS OF VEGETATION. 
development proving unfavourable, it is impos- 
sible to say. Some places now enjoy complete 
immunity from it; and in other places the cultiva- 
tion of the vine, formerly abandoned, is resumed 
with vigour, and with every prospect of success. 
A large percentage of the crop is, however, season 
after season, still lost from this cause ; and pro- 
bably the disease is now so completely established 
that it is vain to hope for its speedy disappear- 
ance. 
The fungus which causes the vine epidemic is 
very minute, covering the affected grape like a 
white cobweb. From its radiating filaments 
several jointed stalks rise vertically like the pile 
of velvet, the upper joints swelling, assuming an 
egg-shape, and giving birth to the reproductive 
spores. It has been proved to be only a stage or 
incomplete state of an Evrysiphe. It makes its 
appearance first as a minute speck on the grape 
when about the size of a pea. It speedily enlarges 
and covers the entire surface of the berry, invest- 
ing it with a net-work of interlacing fibres, ex- 
hausting its superficial juices, and crushing it within 
its embrace. So richly is it furnished with the 
means of propagation, that a succession of seeds is 
developed by the same filament, and three or four 
ripen and are dispersed at the same moment ; 
while, so loosely are they attached to their recep- 
