294 BOTANICAL GAZETTE [ APRIL 



approaching each other until there is eventually, in the mature fruit. 

 a distinct zone of stone cells surrounding the inner tissues. Thi 

 stone-cell layer is not quite continuous, the groups being separated in 

 many places by a few cells which retain their thin cellulose walls and 



* 



afford easy communication between the hypoderm and middle 

 mesocarp (x). The inner contour of the layer is very irregular. 



4. Middle mesocarp (mes). — The cells are thickened, pitted, and 

 gradually increase in size from the small outer layers inward. 



5. Inner mesocarp. — This layer is the great central mass of pink 

 (or yellow) tissue. The cells are of enormous size, often 1 . 25 ram in 

 diameter, and, as previously stated, they can be easily distinguished 

 with the naked eye. The walls are thin and are separated at the 

 angles by intercellular spaces. A sweet, watery liquid fills the cavity. 



Bundles, sieve tubes, and latex tubes are found scattered through- 

 out the mesocarp. 



6. The endocarp consists of one layer of small, very thin-walled, 

 elongated cells as in C. sativus. 



(fig- 25).— This coat, consisting of the usual number 



of layers, is thin but very firm. 



1. 



Epidermis (ep) .—Prismatic cells form 



with a thick cuticle, which occasionally reaches a thickness of 35 M- 

 The outer and inner walls have wavy contours, that of the inner wall 

 being much more pronounced. Each radial wall, which is thicker 

 than in the species previously described, has one thickening in the 

 form of a straight rod pointed at the outer end. Occasionally it 

 branches once dichotomously, the two branches running straight 

 out to the cuticle. These rods are sclerenchymatized, responding to 

 the test with iodin and sulfuric acid. In the colored seeds the brown 

 or mottled appearance is due to the colored contents of the epidermal 

 cells. 



2. The subepidermal layer (sub) consists of a number of layers < 3» 

 sclerenchymatized cells, increasing in number over the edges. 1 ^ 

 outer cells are small and isodiametric; those of the middle layer- 

 large and radially elongated; while the inner cells are noticeabl) 

 small. The cell walls increase in thickness from without in**** 

 those of the inner layer having scarcely any cell cavities. All oi 



wa 1 1 



s are sinuous and deeply pitted. 



