LYCOPERSICUM ESCULENTUM 567 



There appears to be no direct relation between chlorophyll forma- 

 tion or decomposition and the lycopene content of the fruit, as 

 Smith was able to obtain lycopene from mature fruit which had 

 been grown in complete darkness. Furthermore, he found no 

 evidence of lycopene in plastids or of crystals formed from plastids 

 as a result of plastid decomposition; and he was able to demon- 

 strate that there are numerous lycopene crystals in the epidermal 

 cells which are plastid free. Carotene was found in granular form 

 inside plastids as well as after their decomposition, and it also 

 occurs in crystalline and globular forms. 



Structure and Development of Fruit. — Structurally, the 

 fruit consists of the pericarp, placental tissue, and the seeds. The 

 skin of the pericarp has been studied by Groth (11). In all types, 

 it consists of an epidermal layer within which are three, occa- 

 sionally four, well-defined layers of collenchymatous tissue. The 

 epidermis is covered by a relatively thin cuticle; and the polyhedral 

 cells never have sinuous outlines as do those of the leaf epidermis. 

 The number of epidermal cells does not increase greatly with 

 growth of the fruit; and, in consequence, the epidermal cells in 

 mature fruit are much larger than those found in young ones. 

 Except in currant tomatoes, the epidermis develops hairs and 

 glands that are shed as the fruit matures. The hairs are un- 

 branched and consist of three to five cells, while the glands have a 

 unicellular basal stalk and a top of two to four cells. Rosenbaum 

 and Sando (i6) observed that the cuticular layer increased in 

 thickness as the fruit aged, and also noted a complete absence of 

 stomata in the epidermis of both young and old fruits. 



The major portion of the pericarp is composed of large thin- 

 walled cells with numerous intercellular spaces; and, at the time 

 of differentiation of the megaspore mother cell, it is about 8 cells 

 in thickness. According to Smith and Cochran (x9), it continues 

 to thicken, being 14 layers in thickness 60 hours after pollination, 

 and xo layers thick 34 hours later. Two weeks after pollination, 

 when the fruit is about ix mm. in diameter, the pericarp is i8 to 

 30 cells thick. The cells enlarge enormously during development, 

 and this is more significant in the growth of the fruit than the 

 increase in number of cells. As the fruit matures, some of the 

 cells of the inner and central portion of the carpels may partially 

 disintegrate. 



As the ovules develop, there is an outward growth of the paren- 



