ae 
BRIEFER ARTICLES, 
THE “SOFT SPOT” OF ORANGES. 
(WITH PLATE VII) 
In almost any box or lot of oranges in our markets there may be 
found some specimens which have begun to decay. This decay always 
begins and proceeds in a definite and characteristic manner, and is 
common in oranges everywhere, but so far as I can find out its cause 
has never been determined. 
The first sign of the rotting is a slightly discolored spot on the 
rind, which becomes soft and pulpy at this point. This spot rapidly 
increases in extent, so that finally the whole orange is reduced to a 
rotten, mouldy mass, the decay also often extending to other oranges, 
if they be packed close together. The decayed area is at first but little 
different in appearance from the unaffected, but soon it becomes cov- 
ered with a downy, mold-like covering which is white at first, later 
becoming an olive brownish color. After the orange has reached an 
advanced stage of decay various molds appear upon it and produce a 
variety of colors. The rotting affects principally the rind and also the 
central core-like portion. It does not extend deeply into or proceed 
rapidly in the fleshy portion, but produces in it a bitter flavor. 
To ascertain the cause of this decay flasks of orange gelatin, prune 
juice, and prune bread were inoculated with small pieces of the decay- 
ing rind taken from the inner portion which had not been exposed to 
the air. In each case a mold-like mycelial growth was rapidly produced 
from the point of infection, which soon covered the whole nutrient 
substance. This mycelium was at first white, changing later to olive 
brown. Microscopic examination showed that this mold was evidently 
a species of Penicillium, but not the ordinary P. g/aucum. It ditfered 
from the latter in color, and also in the size and shape of the spores, 
those of P. glaucum being spherical and about 4 p in diameter, while 
these were elongated and 10-13 X 6m. The described species nearest 
to this form seems to be P. digitatum Fr., Saccardo’s description of 
1897 ] 103 
