ALMOND. 13 



aleurone cells are usually slightly smaller than those of the almond 

 and the cell walls do not swell noticeably when treated with chloral 

 hydrate. 



In a transverse section the parenchyma layer is found to be thicker 

 than in the almond, while the perisperm is comparatively thin. The 

 endosperm consists of a single layer of cells about 20 p in thickness. 

 The cells of the embryo vary from 15 to 60 p in diameter. The 

 aleurone grains are roundish and granular looking, averaging 8 to 

 10 (ji in diameter but sometimes reaching a diameter of 15 yi. 



PEACH KERNEL. 



(Amyffdalus persica L.) 



The peach kernel is more elongated than that of the apricot, being 

 elliptical rather than circular in outline (fig. 1, D). It is also com- 

 paratively thin, with a rather sharp edge. It resembles the apricot 

 kernel in flavor. According to Rabak the peach kernel comprises 

 only from 6 to 12 per cent of the weight of the peach pit. 1 



Histology. The epidermis of the integument resembles that of the 

 almond more closely than does that of the apricot or prune. The 

 numerous stone cells, arranged singly or in groups, are extremely 

 variable in size, reaching a maximum diameter of 300 JJL. According 

 to Hannig 2 these cells form a continuous layer at the hilum, thus 

 serving to distinguish the peach from the almond, in which these 

 cells are scattered at the hilum as elsewhere. Groups of very small 

 stone cells are common and highly characteristic of this species. 

 They are especially numerous along the vascular bundles, where they 

 often form long chains of cells quite different from anything found 

 in the almond or apricot (PL I, fig. 5). These cells are sometimes 

 15 (JL or less in diameter, although cells 50 [JL in diameter are more com- 

 mon and may be considered about the average. Their height is but 

 little greater than their diameter. As a rule the upper part of the 

 stone cell is much narrower than the base and the outer wall is more 

 thickened than in the almond. 



The parenchyma layer is rather thin and often contains rosette 

 crystals. The endodermis consists of brownish cells averaging 15 

 to 20 [L in diameter which are more easily seen as a rule than in any 

 of the related species. 



In cross section the endodermis appears as a lighter brown layer 

 underneath the darker layer of parenchyma cells. The perisperm is 

 quite noticeable, being in some places 12 to 15 JJL thick. The endo- 

 sperm consists of two distinct portions, the outer part, composed of 

 four to six layers of aleurone cells, which is about 80 JJL thick, be- 

 coming thinner near the edge of the kernel, and the inner portion 



1 Rabak. Loc. cit., p. 28. = Zts. Nahr. Genussm., 1911, 21: 584. 



