1887. ] BOTANICAL GAZETTE. 217 
epidermal surfaces are smooth, without appendages of any 
ind. As the fibro-vascular bundles are little affected in 
the diseased leaf it is not thought necessary to describe their 
structure. 
The fungus was found to be fully matured at the first date 
of gathering. It makes its appearance very early in the de- 
velopment of the leaf, and in most cases seems to start some- 
where in the upper half, as a small puff or swelling in the 
tissue. This spreads until in many cases it affects nearly the 
whole leaf. The fungus stimulates the growth of the paren- 
chyma, giving rise to cell-division and thus to a greatly 1n- 
creased area of the surface. Fig. 2 shows two cells, @ and 6, 
in process of division. Attention was called to them by the 
fact that they were full of protoplasm while the sauna es 
much altered, as may be seen in fig. 3, in which @ 1s the 
upper and 6 the lower surface, corresponding to @ and 6 in 
fig. 1. The epidermal cells have changed in form and their 
walls are much thicker. The long. narrow palisade cells 
*Kryptogamen-Flora, Ascomycetes, p. 6. 
