Pigott. — Notes on Nothopanax arboreum. 



605 



of both male and female plants by transversely elongated cells, rectangular 

 in longitudinal section. These cells are at first from five to nine layers deep, 

 but the number of rows increases with further development, extending almost 

 to the axial bundle in the fully grown fruit. In the young buds and flowers 

 the carpels are seen to be oval in cross-section. Soon, however, this shape 

 is altered, owing to the appearance of longitudinal ridges traversing the 

 cavity on both sides near the middle. The cavity is thus almost divided 

 into two compartments, and presents a dumb-bell shape in cross-section. 

 In the male flower this wall does not achieve any great thickening of its 

 cell- walls, although the ridges are formed (fig. 4). In the female flower 

 the ovarv-wall gradually thickens its cell-walls, which later become ex- 

 tremely hard and wooden (fig. 5). The cells are fairly regular in shape 

 and position, being arranged in rows. In the thin-walled stage they have 

 protoplasmic contents, and usually a single nucleus, though occasionally 

 two or more have been noticed. The end walls of these cells are at right 

 angles to the lateral walls, although, at the curves in the ovary-wall, from 



fv.b. 



Fig. 4. — Longitudinal .section of ovary-wall in young male and female flowers with 

 unthickened cell-walls, x 175. 



Fig. 5. — Longitudinal section of ovary-wall in mature fruit with much-thickened cell- 

 walls. X 175. 



Fig. 6. — Cross-section of developing ovary-wall, showing frayed cell-walls and multi- 

 nucleate cells. X 175. 



the irregular manner in which the cells here fit into each other, the ends 

 appear to be more or less tapering. These long cells of the wall are inter- 

 rupted by columns of parenchyma cells at the outer edges, and at the axis 

 connecting the two carpels, running between the two branches of the axial 

 fibro-vascular bundle. Near the top these parenchyma cells extend right 

 to the cavity of the ovary, but for the greater part of the length of the ovary 

 at least one layer of woody cells is continuous. As the cavity enlarges, 

 the inner layers of cells become stretched to their utmost capacity, and 

 are often frayed in the process (fig. 6). In the mature ovary the only dis- 

 continuity in this wall is seen at the origin of the funicle and arillus, where 

 their place is taken by large-celled parenchyma. 



