30 STUDY OF NUTS MICKOSCOPIC IDENTIFICATION. 



to 12, is doubtless subject to some variation. The procambium 

 consists of a layer about three cells thick composed of thin-walled 

 cells about 16 to 20 pi in cross section. They are elongated in the 

 direction of the long axis of the embryo. The medullary tissue is 

 composed of parenchyma cells rather more compactly arranged than 

 in the cortex ; they are also more angular in outline than the cortical 

 cells, often radially elongated, and so arranged that the radial rows 

 of cells, united end to end, may be traced for some distance through 

 the tissue. Their diameter averages 50 to 60 pi, while individual cells 

 occasionally reach a length of 100 [A. The vascular bundles, already 

 mentioned, occur at rather wide intervals, and are very slightly devel- 

 oped. They usually contain two or three spiral vessels about 8 pi in 

 diameter. 



The arrangement of the various tissues is shown in the section 

 in Plate III, fig. 2. 



The cotyledons of the Brazil nut are very small and are located 

 about 5 mm from the distal end of the kernel. They can sometimes 

 be found with the aid of a lens after soaking the kernel in water. 

 In a longitudinal section they appear closely appressed to the side 

 of the kernel underneath the endosperm and measure about 750 by 

 175 pi. At the base of the cotyledons the cells of the cortex become 

 reduced in size and for a short distance it is no longer differentiated 

 from the medullary tissue, but continues above the base of the cotyle- 

 don as a thinner layer of tissue. 



The reserve food stored in the kernels consists of oil globules and 

 aleurone grains. The latter are irregular in shape, of large size, 

 often 30 pi in length, and contain a large crystalloid and one or more 

 globoid bodies. 



The sapucaia nut (LecytMs usitata Miers) is very similar in struc- 

 ture to the Brazil nut. The cortex is somewhat thicker, equaling 

 the diameter of about 14 cells. The endosperm consists of but a 

 single layer of cells and the inner integument is very thin and con- 

 tains rosette crystals. 



PISTACHIO NUT OB GREEN ALMOND. 



(Pistacia vera L., Family Anacardiacece.) 



The pistachio nut is the seed of a tree native to the Mediterranean 

 region and introduced sparingly into this country. It is, however, 

 too tender for cultivation except in California and the southern 

 States. The fruit, which is produced in clusters, is of the nature of 

 a drupe with flesh that becomes dry at maturity, and a smooth stone 

 or pit which separates easily into two valves. The seed roughly re- 

 sembles in shape an elongated buckwheat grain ; that is, it is approxi- 

 mately though irregularly triangular in cross section, blunt at one 



