604 



Transactions. 



in the anther-sac. They are three-sided in cross-section, and have, 

 when ripe, a pale-yellow colour. The external wall is marked by regular 

 sculpturings, in addition to three prominent longitudinal ridges. The cells 

 bordering the connective tissue and the epidermis do not form mother cells, 

 but form the tapetum — a layer which becomes disorganized, helping in 

 the development of the pollen-grains. Each pollen-grain consists of two 

 cells, with clear nuclei, which can occasionally be seen through the walls. 

 Development here is the typical development of a dicotyledon. In the 

 male flowers the anthers are yellow, but in the female flower the staminodes 

 never lose their greenish colour. The anthers become broken off, and often 

 all that is left is a portion of the thickset filament alternating with the 

 petals. 



Stigmas. 



The stigmas are bifid, the outer surface of each lobe being protected 

 by a continuous epidermis. The inner surfaces, however, on diverging, 

 present a slightly papillate stigmatic surface (fig. 2). The cells immediately 

 below the stigmatic surface are vertically long and narrow, with thin walls, 

 and are ioosely packed. In many sections this tissue tended to break down, 

 owing to its delicacy. It thus facilitates in every way the entrance of a 

 pollen-tube ; yet in no case was one seen, even when pollen-grains were ob- 

 served on the stigma. The style-arms, still in their divergent position, 



Fig. 2. — Stigmatic surfaces and tissue of style of mature fruit. X 175. 

 Fig. 3. — Longitudinal section of portion of young fruit, showing X -sna P ec ' mass of 

 thick -walled tissue at the base of the style. X 28. 



persist through the formation of the fruit, but are, of course, relatively 

 much smaller. The tissues of these arms, surrounding the central column 

 of long cells, comprises a cylinder of loose irregular cells. In some cases 

 the tissue below the style was of thick-walled regular cells, the thickening 

 being of cellulose. The characteristic shape of this mass of tissue was that 

 of an inverted stool, the disc extending towards the funicles of the ovules. 

 This tissue was not observed till after the earliest stages in the development 

 of the endosperm (fig. 3). 



Ovary-wall. 



Very shortly after the male flowers have all fallen the ovary of the 

 female flower begins to increase greatly in size, and microscopic examination 

 showed that the cavity of the ovary is lined in the young flowers and buds 



