New York AGRICULTURAL EXPERIMENT STATION.+ 181 

Sa 
——4 
Fig. 6. From deeper lying portions of the same sections as Fig. 5. 
(x 375). The cells here were smaller and thicker walled. In a, the 
bacteria were abundant in the intercellulars and the middle lamellae partly 
disssolved; b, from a little deeper, showed less advanced action, the walls 
swollen and laminated but still cohering. 

Fig. 7. Cell mebrances from the central part of* the same sections 
(x500). The earliest stages of bacterial invasion along the plane of the 
middle lamellae are shown in a and b, while e shows the action upon the 
walls in advance of invasion. The -laminated structure appears both in 
the swollen inner lamellae and in the undissolved portions of the middle 
iamellae which occur at the angles of the cells. 
lamellae also becomes less refractive, though not softly trans- 
lucent, as do these adjacent inner layers, and soon begin to 
melt away in the thinner portions. The middle lamellar sub- 
stances, as already explained, usually form thicker masses at 
the angles of the cells, often triangular as seen in optical 
section. As the thinner parts dissolve, these heavier portions 
remain isolated. There are now distinct openings between 
the adjacent cells in most places and the swelling of the walls 
has reached its maximum. Tapping on the cover glass, tear- 
ing with needle point or other mechanical test, will show that 
