108 JOURNAL OF THE [October, 



of the cleft, filled with the brown cellular tissue. In germination 

 the embryo issues from the little depression (Fig. 5), the root 

 descends into the soil, the plumule rises with its successive leaves, 

 but the extremity of the single seed leaf remains within the stone. 

 The entire mass of the stone, excepting the firm brown coating, 

 the embryonal cavity, and the cellular structure of the cleft, is 

 a remarkably uniform, bluish-white endosperm, without flaw or 

 blemish, nearly as hard as bone. The cells of this endosperm are 

 of various sizes and forms, but many of them are long spindles, 

 and the "grain" of the entire inner structure, caused by the 

 adjoining rows of cells, considering their longer diameters, always 

 lies in the direction of radii, converging from the hard outer coat 

 toward a longitudinal axis, lying within the cellular structure of 

 the cleft. Therefore the sections must lie in the planes of these 

 radii, or in planes perpendicular to the radii, to avoid the con- 

 fusion resulting from cutting the cells obliquely. 



All the sections exhibited are taken at the middle of the stone, 

 slightly below the position of the embryo. The transverse section 

 extends entirely across the solid substance of the endosperm from 

 the hard outer coating to the soft tissue of the cleft. The longi- 

 tudinal-radial section extends in the plane of one of the radii^ 

 running from the hard coat to the long axis. And the longitudinal- 

 tangential section lies in a plane perpendicular to such radii. 

 These last sections were obtained by shaving off the hard coat 

 longitudinally for only a slight depth. Deeper cutting, of course,, 

 gradually approaches the position of a longitudinal-radial section. 

 In preparing the sections the stone was split open by the blow 

 of a hammer on a knife blade, applied longitudinally and trans- 

 versely, and the pieces were macerated for a few days in cold 

 water, with one drop of carbolic acid solution to the ounce to 

 prevent putrefaction, or in a moderately strong solution of caustic 

 soda. Either process will soften the stone sufficiently for cutting, 

 but the soda more rapidly disintegrates the layers of the outer 

 brown coating, thus preventing the view of these cells in their 

 natural position. The sections were cut free-hand with a razor. 

 The necessarily varying thickness of such a section is very 

 instructive. In the thicker portions of the section the relations 

 of the cells to each other will be seen, where they lie in several 

 layers; while the internal structure of the several cells will be 



