May 1,1925 Necrosis, Hyperplasia, and Adhesions in Tomatoes 
875 
markings without the blister effect 
(pi. 2, A) and in some cases the entire 
surface of the fruit is involved, a 
condition associated with early abscis¬ 
sion or invasion by rot-producing or¬ 
ganisms. The discoloration may some¬ 
times be internal and deep seated so 
as to show through the outer peri¬ 
carp layers as an evident darkening of 
the underlying tissues (pi. 3, B). 
The surface lesions may become 
hard, dark brown scabs which inhibit 
the symmetrical growth of the fruit 
and as a result produce marked mal¬ 
formation, as is shown in Plate 2, C. 
Often the brown necrotic lesions in¬ 
volve the pericarp so deeply that, after 
the affected tissues collapse, the weak¬ 
ened areas are ruptured by the growth 
pressure of the interior tissues, and large 
irregular openings are produced in the 
pericarp exposing the seeds and placen¬ 
tal matrix to the drying effects of the 
air (pi. 2, B and D). In fruits thus 
affected when very young, as shown in 
Plate 2, A, mere shreds of the pericarp 
may remain as is shown in Plate 3, C, 
or deep cracks may result as shown in 
Plate 3, D. 
When the fruit is cut across it is 
found that brown necrotic regions 
usually occur throughout the interior 
tissues if there are any external lesions 
on the specimen (pi. 3, A) and in cases 
of extensive surface discoloration all 
or considerable portions of the interior 
may also be similarly discolored. 
Ordinarily, however, the internal ne¬ 
crosis occurs in the form of scattered 
strips, pockets, or thin lasers, not 
continuous or connected with each 
other nor, as a rule, sufficiently ex¬ 
tensive to completely inhibit the en¬ 
largement of the fruit, although its 
normal development may be seriously 
interfered with. The necrotic regions 
occur most abundantly in the placental <• 
matrix that fills the locules, and the 
most prevalent type consists of rather 
extensive necrotic planes parallel to and 
in rather close proximity to the locule 
walls. These necrotic regions are 
usually but not always surrounded or 
bounded by zones of rather firm, glassy 
or translucent tissue. In young ovaries 
many of the ovules are entirely necrotic 
and atrophied. This occurs usually in 
only part of the locules and often 
involves only part of the ovules in the 
locule. Many mature seeds show 
brown spots. 
Examination of razor sections of the 
young fruits with a hand lens reveals 
very clearly the necrotic regions and 
the translucent zones associated with 
them and also shows rather extensive 
cavities associated with the necrosis of 
the distal portions of the placental 
matrix. These cavities may be en¬ 
tirely surrounded by a brown necrotic 
lining as is the small one in Plate 4, A, 
or may occur between the necrotic 
placental surface and the locule wall 
as in Plate 1, E. Furthermore many 
of the seeds may be displaced or ab¬ 
normally located and oriented in the 
placenta, and the normal arrangement 
of the placental matrix as shown in 
Figure 1 is very generally interfered 
with to a greater or less extent. It is 
plainly evident also that necrosis often 
occurs within the seeds, that some 
ovules are affected more than others, 
and that various degrees of retarda¬ 
tion in the development of the seeds 
and the placental matrix occur in the 
same fruit and even in the same locule. 
For example, certain 'ocules in fruits 
5 mm. and 7 mm. in diameter showed 
necrotic atrophy of the ovules and 
complete suppression of any develop¬ 
ment of the placental matrix beyond 
the stage shown in Figure 1, A. 
NECROSIS, HYPERTROPHY, AND 
HYPERPLASIA 
Microscopic examination of un¬ 
stained sections shows that the surface 
blisters are produced by a compact 
muriform cushion of meristematic cells 
which have pushed up the epidermis 
(pi. 1, A). Epidermal pustules or 
intumescences of all sizes are found, 
the smaller ones being papillate rather 
than flat-topped. In the incipient 
stage of a blister, necrosis of the 
epidermal cells is visible and the 
hyperplasia is seen to originate in the 
first and second subepidermal cell 
layers (pi. 5, A). The translucent 
quality of the blisters is very evidently 
attributable to the lack of intercellular 
spaces in this hyperplastic tissue 
(pi. 5, B). 
Zones of brown necrotic cells of 
varying shape, extent, and orientation 
are of common occurrence at varying 
depths in the pericarp, producing, as a 
result of collapse of the necrotic cells 
(pi. 6, B and C), dark sunken pock¬ 
marks on the exterior of the fruit. 
Such zones often involve the entire 
thickness of the pericarp and, as a 
result of early atrophy of the tissues 
(pi. 6, A) or collapse of the necrotic 
cells (pi. 3, E; pi. 6, C), produce weak¬ 
ened places in the pericarp which are 
easily ruptured by growth pressure. 
This results in such fruits as are shown 
in Plate 2, B and D, and Plate 3, G and 
D. Similar necrotic regions occur 
scattered promiscuously through the 
locule walls and the placental tissue, 
