160 THE BOOK OF THE ROSE chap. 



The spores or seed are set free from their winter 

 resting places by the heat of early summer, and float 

 in the air, some at least commencing to germinate and 

 throw out roots even before they alight. Like other 

 parasitical fungi-spores, a certain condition of the 

 atmosphere and also of the leaves on which they fall 

 is necessary for the actual development of the fungus 

 growth ; when these are present the first visible sign is 

 a spot or curl on a young leaf, which is raised or 

 depressed according as the mildcAV has attacked the 

 upper or under surface. 



It should be noticed, as an important thing to 

 remember, that the mildew is always worst on the 

 under side of the leaf, and is often found there alone. 

 For this at once puts aside as useless the merely 

 dredging the affected parts with sulphur, as this 

 cannot touch the worst places ; and it is evident that 

 it must be puffed from below as well as from above, 

 and that in all swinging with liquid the under surfaces 

 of the leaves must have even more attention than the 

 upper. 



The first thing the mildew spore does when it begins 

 to groAv on the Rose-leaf, is to form the mycelium — 

 the tiny white threads which are common to all fungus 

 growth from mildew to the mushroom of the fields. 

 This, when woven closely together in masses, forms the 

 spawn, and then the white efflorescence is seen on the 



leaf. 



The leaf breathes through pores on the under surface : 

 these are choked by the woven mass of mildew spawn, 

 which also pierces the membranes and lives upon the 

 juices. The leaf may thus be said to be suffocated and 

 bled to death at the same time. 



At such a time — the first appearance— ^^Ae time for 



