588 THE STRUCTURE OF ECONOMIC PLANTS 



emergences. The young fruits of practically all varieties bear 

 hairs of one or more kinds which may or may not persist until 

 maturity. The skin may be white, green, yellow, red or, in some 

 cases, variously spotted and striped. 



ANATOMY 



Anatomy of the Fruit. — Despite the pronounced variation in 

 shape, size, and color, the anatomical characters are fairly constant; 

 and Barber (z) has pointed out that a generalized description of 

 the fruit coat can be given for C. Pepo and C. maxima which 

 closely resemble each other in structural detail. At maturity, 

 the rind of the fruit is hard, while the central hollow portion 

 contains a mass of slimy fibers among which are the numerous 

 flattened seeds. The pericarp and undi verged tissues of the 

 receptacle constitute the bulk of the fruit, including the rind and 

 fibers, and the connecting parenchyma disintegrates before the 

 complete maturation of the fruit. 



Barber (i) has divided the pericarp into six distinct regions. 

 The outermost zone (i) consists of prismatic cells that are polyg- 

 onal in surface view and form a palisade layer, having greatly 

 thickened outer and radial walls with a heavy striated cuticle. 

 The characteristic white spots on the surface, about which the 

 cells are elongated and curved, are stomata from which rows of 

 tangentially elongated cells radiate. The distribution of the 

 stomata is not uniform and occasionally two may be surrounded 

 by the same group of radiating cells. Yasuda (41) has reported a 

 frequency of 44 stomata per square millimeter for C. Pepo. Two 

 types of hairs are produced on the epidermal surface, both having 

 basal cells that are somewhat more rounded than the adjacent 

 epidermal cells. These hairs do not persist, but dry up while the 

 fruit is small, leaving the basal cell intact. The large, jointed 

 type is tapering, conical, and multicellular, frequently attaining a 

 length of i}'i to ^ mm The other is smaller and capitate, con- 

 sisting of a jointed structure of four or five cells, and a large globular 

 head of one or more cells. (Fig. 308, B.) 



The hypodermal zone (x) consists of many layers of small, 

 thick-walled, isodiametric cells with small intercellular spaces. 

 The outer mesocarp (3) lies immediately within the hypodermis 

 and is comprised of cells of graded size, intermediate between those 

 of the hypodermal region and the larger ones of the middle meso- 



