Brooks . — Observations on the Biology of Botrytis cinerea. 483 
ascertain how soon after the inoculation with spores, of the leaf just 
beginning to turn yellow, the penetration of the germ-tubes began, the 
following method was adopted : — Leaves just beginning to turn yellow 
were inoculated with spores, and from day to day the areas of the leaves 
on which the spores had been placed, were cut out and fixed in Flem- 
ming’s weaker solution, and afterwards microtomed and stained. Upon 
examination of the sections it was found that the germ-tubes had already 
begun to penetrate the tissues the first day after inoculation. The germ- 
tubes pierce the cuticle and soon ramify in the cells which they have 
destroyed, as will be seen in the accompanying figures. It will be ob- 
served in Fig. 3 that the nuclei of the developing hyphae are extremely 
numerous, but very small. In Fig. 4 the nuclei are seen under a greater 
magnification. 
F is 3 
These yellowing leaves must be considered to be in the incipient stage 
of decay, for they were never observed to recover their normal colour. 
They are by no means c dead ’, however, if the term ‘ death ’ be applied 
to the state when the cells cease to be plasmolysable. These yellowing 
leaves live several days before they become flaccid and collapse. It would 
