54<> MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



Stimulus of fertilization. The wall of the ovary develops as 

 two distinct layers. The inner, or endocarp, composed of rela- 

 tively few cells, becomes firm and leathery or, as frequently de- 

 scribed, cartilaginous. The outer, consisting of mesocarp and 

 exocarp remains soft and pulpy, and is traversed by numerous 

 small libro-vascular bundles. The innermost edges of the carpel- 

 lary wall come together forming a drupe-like suture, while the 

 outer tissues lose their identity and become indistinguishable 

 from the torus. Thus the conditions of a drupe are fulfilled and 

 if the ovary of the apple were superior, developing free from the 

 torus, the resulting fruit would be a close approach to a true drupe. 

 As it is, the ovaries are inferior and are embedded in the torus 

 which grows with the carpels. This is shown in the three sections 

 of fruits in figures 2, 4, and 9, plate 39. The demarcation of 

 the various tissues can be seen in figure 2 with the exception of 

 the endocarp, which is only distinguished as the darkened border 

 of the ovarian cavity. The exocarp is limited by the series of 

 small fibro-vascular bundles appearing in the figure as a row of 

 small dots. The tissue next in position extending from the 

 exocarp to the primary vascular bundle is conspicuous by the 

 absence of all vascular tissue. This zone of tissue may be called 

 the pith of the apple and is continuous with the pith of the stem. 

 The cortex or remaining tissue is separated from the pith by ten 

 primary vascular bundles. 



The vascular structure of the apple has long been studied. 

 Ten primary strands are described in Miller's (45) Garden 

 Dictionary as occurring very regularly in the apple, one at the 

 point of each cell of the "capsule" and one in the middle between 

 the other five. Loudon (9) makes a somewhat similar statement, 

 adding that the bundles tend toward the calyx. Decaisne (11) 

 in a figure of a longitudinal section of the apple shows the primary 

 vascular strand with the dorsal strand of the carpel arising from it. 

 Recently ^IcAlpine (46, 47) has worked out the fibro-vascular 

 system of the apple and pear. In the apple jMcAlpine shows ten 

 primary vascular bundles supplying the "flesh" and secondary 

 branches sui)plying the "core." In the pear, he states that as 

 each one of the li\e primary bundles approaches its corresponding 

 carpel, it gives rise to an internal branch which passes along the 

 dorsal or outer face of the carjK'l, while the main portion of each 



