272 BOTANICAL GAZETTE [NOVEMBER 
enveloped with a layer of endosperm 4o to 50 uw in thickness, and 
as reported by YouNG (35) is ‘‘plainly differentiated into cortical 
and medullary tissues separated by a layer of procambium along 
which rudimentary vascular bundles are arranged at intervals.” 
There is a single, somewhat irregular layer of epidermal cells just 
beneath the endosperm, and within 5 mm. of the distal end are the 
two very minute, unequal cotyledons which “‘measure about 750 
by 175 #” (1, 25). The cortical and medullary cells are similar 
in shape and size, and are largely filled with oil and proteid bodies. 
The endosperm cells, arranged with the long diameter at right 
angles to a median plane, are especially rich in proteids (28). The 
procambium cells with the long diameter at right angles to that of 
the endosperm cells contain few or no proteid grains (fig. 1). 
The outer seed coat or shell is made up of two layers; the outer 
with its crinkled surface is light brown and softer in texture than 
the inner layer, which is dark brown and has a glazed inner surface. 
In the angles of the shell this layer seems to be of two layers which 
divide, leaving spaces filled with still another tissue that is lighter 
in color and softer in texture than the outer of the shell layers. In 
the micropylar angles of the seed is a narrow cavity. Such cavities 
are termed by BERG (1) the “‘loculi spurii in testa,” and extend the 
entire length of the shell. This open channel probably serves as 
the usual entrance of the parasites of the nut (fig. 1). 
The tissues of the seed, taken in order, beginning with the shell 
are: (1) outer seed coat in two distinct layers, with a softer tissue 
filling the triangularly prismatic corners; (2) the thin inner seed 
coat which may or may not adhere to the kernel; (3) the endosperm 
layer, two cells thick; (4) epidermis, a single-celled layer; (5) cor- 
tex, of large storage cells; (6) procambium layer, generally three 
cells thick; (7) the medullary tissue, of large storage cells. 
Diseases of the Brazil nut 
1. BLACK CRUST 
GENERAL DESCRIPTION.—Fully 5 per cent of all diseased Brazil 
nuts are affected with black crust, but there is no external indica- 
tion of their condition, since the shells are normal in color and the 
