PAPERS ON BOTANY 219 
In the more advanced stages the red color usually increased 
and the size of the hard brown spots became larger. The sur- 
face was in many cases slightly depressed and the round of the 
apple would be changed showing that there had been a stoppage 
of the growth of the cells on that side. 
The outline of the spots in the later stages became definite, 
usually round (Plate II.) The color was then almost black 
with a brilliant red surrounding it. This was brightest at the 
border and radiated out over a large part of the apple, some- 
times covering half of it, becoming less and less bright, and 
usually ending in a mottling or striping. 
The size of the spot varied from 2 millimeters to about 3 cen- 
timeters in diameter. The progress of the fungus is very slow. 
Two apples were marked on the twelfth of November, and on 
the twelfth of March there was not more than 2 mm. of 
growth on the blackened portion of one, the reddened part 
apparently remaining the same, and no change at all in the 
other. The growth probably takes place in the orchard, as the 
truit develops. 
STRUCTURE IN CROSS SECTION 
The fungus in the deepest spots observed penetrated only 
about 3 mm. deep. The average was from 1 to 2 mm.. Plate 
I, Figs. 1, 2, 3, 4, 5,, give an idea of the appearance of the 
spot in cross section, 
The growth of the mycelium into the tissue caused the flesh 
tc turn brown, the cells becoming corky and hard, and they 
were filled with a large quantity of starch (Plate I, Fig. 6). 
Starch was not present in the healthy cells, (Plate I, Fig. 7). 
The fungus appeared to be present only in the brown areas, 
In the very early stages no infected cells were seen but from 
such spots Alternaria was isolated. The depth of the diseased 
tissue varied with the degree of darkness of the epidermis. 
The tissue was slightly bitter to the taste, and hard to chew as 
compared with the healthy flesh. 
The mycelium of the fungus can plainly be seen in the cells 
of the infected tissue (Plate I, Fig. 6). Under the very dark 
portions of the skin the mycelium was abundant, while under 
the lighter colored areas it was more difficult to find. Under 
the reddened portion of the skin radiating from the spot, none 
was apparent, and no culture was produced from this region. 
