Feb., 1923] BARTHOLOMEW AND OTHERS— INTERNAL DECLINE 
69 
Internal Symptoms. The first internal symptoms are usually found near 
the vascular bundles in the “nipple” of the peel at the stylar end of the 
lemon. Small cylindrical openings are found arranged in a circle within 
the ring of vascular bundles. It is evident that these openings have been 
produced by the collapse of the parenchymatous cells. A little later in the 
development the vessels themselves appear to be clogged with a pinkish to 
rust-brown deposit of gum. At this stage the vessels and the surrounding 
tissues often begin to break down, and finally the central portion of the peel 
of the stylar end of the lemon becomes a mass of gum having the character¬ 
istic pink to rust-brown color. In other cases the vessels are clogged with 
gum but there is very little indication of collapse in these or adjoining tissues. 
This is true for the examples shown in Plate VII. In conjunction with 
these conditions, pink to rust-brown splotches frequently appear at one or 
more places within the adjoining tissues (see c, PI. VII). The tissues in 
these splotches, at this time, usually have a glossy appearance due to the 
formation of gum. At this stage the cells and the juice sacs of the pulp 
adjoining the peel at the stylar end of the lemon become affected, lose 
water, and collapse (see b , PI. VII). There is very little or no discoloration 
of these tissues at this time. In comparatively rare cases the vessels in 
the center of the lemon are discolored and filled with gum all the way 
through to the stem end. This is usually as far as the trouble has progressed 
in lemons that are picked while light or dark green in color. 
Silver Fruit 
External Symptoms. Internal decline is not easily detected by external 
signs at this stage of development of the fruit. In many cases the more 
intensive coloring of the peel at the stylar end of the lemon is an indication 
that the abnormal breaking down of the internal tissues has begun. How¬ 
ever, as is true with the green fruits, this indication often may be misleading. 
Internal Symptoms. The loss of water and the collapse of the pulp cells 
and juice sacs at the stylar end continue. The progress is more rapid near 
the center of the lemon than out near the peel. It is especially rapid in 
the pithy core (placenta) that runs through the center of the lemon (see 
PI. VII). As the fleshy pulp tissues dry out they may retain their normal 
color, but more often they assume a pinkish or light-brown color. In this 
stage of growth of the lemon it is found that, in those having internal 
decline, the breaking down of the tissue has progressed so far as to involve 
parts of the inner portion of the peel and perhaps a fifth of the adjoining 
pulp at the stylar end. 
Yellow (Tree-ripe) Fruit 
External Symptoms. Here again the signs are far from being infallible. 
The more intensive yellow or orange-yellow coloring of the stylar end, 
which may occur while the remainder of the fruit is still green, persists 
