PLATE XXXIX 



Fig. I.— A rotting area in an overripe fruit of S. D. No. 3. In the healthy portion 

 at the right the middle lamella is still intact, while in the rotted portion the cells are 

 free. This is a resistant variety. X 216. 



Fig. 2. — ^Tip of hypha in Opata plum. The middle lamella is being split slightly 

 ahead of the hyphae. This is apparently not due to mechanical pressure, as the walls 

 in contact with it are collapsed. X 200. 



Fig. 3. — The edge of a rotting spot in a green fruit of Opata plum. The middle 

 lamella is dissolved in advance of the penetration of the hypha. This is a susceptible 

 variety. X 216. 



Fig. 4. — Tissue of apple infected with Penicillium expansum. A short piece of 

 hyphae may be seen in the center of the figure. The middle lamella is completely 

 dissolved. X 156. 



Fig. 5. — Cross sections of hyphae in tissue of Opata plum 18 hours after inoculation. 

 The dark areas are collapsing cell walls. The hyphae are entirely intercellular. X 400. 



Fig. 6.— Portion of the rotted area of an Opata plum 18 hoiu-s after inoculation. 

 Although only few hyphs are present, the middle lamella is completely dissolved. 

 X 200. 



