18 



STUDY OF NUTS MICROSCOPIC IDENTIFICATION. 



in breadth. The guard cells are horseshoe-shaped, not so thick as 

 those of the Persian walnut. As a rule, the ends fit together squarely, 

 so as to inclose an opening four or five times as broad as it is long. 

 One guard cell often remains but slightly developed, and in some 

 cases both guard cells appear shriveled. As seen in the section (fig. 

 3, B), the outer tissue consists in general of a single layer of cells 

 25 to 30 |x thick, while the inner tissue is not noticeably different from 

 that of the Persian walnut, though sometimes only 15 (A thick. 



The endosperm is from 40 to GO \L thick and consists of from one 

 to three layers of cells. It has a thick hyaline outer wall, which may 



A B 



FIG. 3. Butternut: A Epidermis of integument (X175); B Section of integument 

 and superficial tissues of kernel ( X175). 



possibly be regarded as the perisperm. The embryo has the same 

 structure as in the last described species. The aleurone grains aver- 

 age 7 to 8 [x in diameter and seldom exceed 12 pi. 



BLACK WALNUT. 

 (Juglans nlgra L.) 



Up to the present time the native black walnut has been of greater 

 importance as a timber tree than as the source of a food product. 

 The nuts, however, are placed upon the market each year, and while 

 they have not as yet met with great demand, the uses to which they 

 may be put are now on the increase, and the demand is proportion- 

 ately greater. The shell of the black walnut is usually thick and the 

 kernels are not always plump. The flavor is quite distinctive, being 

 greatly relished by some and disliked by others. 



The black walnut is approximately spherical, slightly flattened 

 at the sides and usually somewhat prolonged at the ends. The sur- 

 face is roughened, but to a less extent than in the butternut. Accord- 

 ing to Lazenby, 1 the proportion of kernels varies with the size of the 



1 Composition and Waste of Fruits and Nuts. Froc. Soc. From. Agr. Sci., 1903, p. 101. 



