28 STUDY OF NUTS MICROSCOPIC IDENTIFICATION. 



25 \L in diameter. The tissue of the cotyledons consists of paren- 

 chyma cells with thinner walls than those of the endosperm, varying 

 in diameter from 20 pi in the outer part to 50 to 75 \L in the interior. 

 Intercellular spaces, though present, are very small. These cells con- 

 tain oil and spheroidal aleurone grains up to 20 [A in diameter, the 

 structure of which has been described by Hanausek. 1 The arrange- 

 ment and relations of the various tissues are shown in Plate II, 

 figure 4. 



PINE NUT OB PINON. 



(Pinus sp., Family Pinacece.) 



The large edible seeds of a number of species of pine are employed 

 as food, both in this country and in Europe. The American Indians 

 in particular formerly made great use of the seeds of Pinus edulis 

 Engelm., P. cembroides Zucc., P. Monophylla Torr. and Frem., and 

 others. In some parts of the West at the present day the Indians 

 collect pine nuts in considerable quantities, both as food and for sale. 

 The pines of Europe producing edible seeds are P. cembra L. and 

 P. pinea L. 



It is necessary to collect and roast the cones in order to cause the 

 scales to spread apart, after which the seeds are easily dislodged. 

 Pine nuts are prepared for market by cracking, after which the deli- 

 cate, loose-fitting inner integument is easily rubbed off, only traces 

 of it being found in the samples examined. These were of the kinds 

 offered by dealers, and it was not possible to determine the species. 

 The structure of the various kinds is, however, very similar. 



The kernel is irregularly long-ovoidal in form, white, oily, and 

 of a delicate, often slightly resinous aromatic flavor. The thick 

 endosperm surrounds a cylindrical cavity containing the straight 

 embryo, which consists of a rather large radicle bearing at its extrem- 

 ity a whirl of cotyledons inclosing the growing point of the embryo. 

 Woods and Merrill 2 report about 60 per cent of kernels and a chemi- 

 cal composition varying considerably with the species. 



Histology. The pine nut is simple in structure and lacks charac- 

 teristic features. The kernel is covered by a thin brown membrane 

 composed of large cells commonly varying in the nuts examined from 

 400 to 600 [L in length and from 60 to 80 ^ in breadth. (PL III, fig. 1.) 

 The walls are thin and the cells as a rule have a more or less collapsed 

 appearance. 



The endosperm consists of thin-walled parenchyma cells varying 

 in diameter in different parts, but averaging about 40 JJL. The cells 

 of the embryo are similar, but somewhat smaller. The reserve food 



a Ref. by Winton in Microscopy of Vegetable Foods, 1906, p. 311. 

 2 Loc. cit., p. 83. 



