STRUCTURE. 93 



and madagascariensis show an inclination to the formation of ridges as in 

 the second type, with a reduction of the hairs. 



The outer coat of N. flava is peculiar in several points. It is cov- 

 ered with long, slender, appressed hairs just visible to the naked eye, 

 springing from all sides of the cells. It thus combines the characters 

 of the third and fourth types of Weberbauer. The cells are extremely 

 wavy superficially, and so irregular in shape as to render the longitudinal 

 rows obscure. They differ from those of all other species investigated in 

 being nearly twice as deep as wide. A great amount of induration of the 

 outer walls leaves the lumen as a small pear-shaped space at the inner 

 end of the cell. This is a striking approach toward 

 the narrow columnar structure of the hard layer of 

 Victoria and other genera of Nymphaeaceae. I find 

 that N. tetragona belongs plainly to the first type of : 

 seed coat according to Weberbauer, and N. clegans to 

 the fourth type. 



The inner seed coat is pressed to a thin layer, 

 except at the tip of the nucellus. The walls are Fl ^.-Distribution of 



vascular bundles from the 



thickened on the inner side, but as it approaches the ctmiaza, m seed coat of iv. 



,,,.,. alba. After Chifflot. 



micropyle the thickening extends up the side walls, 

 until at the micropyle only the outer walls are unthickened. With this 

 thickening there is an increase in the height and sinuosity of the side 

 walls. The micropyle is closed by slightly thickened rounded cells and 

 a layer of thinner cells overlying the inner coat (cf. Fig. 44). A vascular 

 bundle passes along the raphe, and spreads in the seed coat irregularly 

 (Fig. 43), as figured by Chifflot (1902). 



Nine-tenths of the space of the seed is occupied by perisperm 

 (nucellar tissue). This consists of large, thin-walled polyhedral cells (Fig. 

 44, p*), densely packed with starch. The outermost cells of the nucellus 

 are shriveled and compressed together into a thin membrane, which is 

 thickest between the embryo and the seed coat. The outer food-storing 

 cells are small and somewhat flattened, but in most of the nucellar tissue 

 they are elongated and disposed somewhat in lines (Leitungsbahnen of 

 Weberbauer) running obliquely upward toward an air-space beneath the 

 embryo. The central axis of the seed is filled with looser, thin, elongated 

 starch-laden cells. The nuclei of the cells, where distinct, are pressed 

 over against one wall. The starch is in simple or compound granules, 

 and these, in N. gladstoniana and odorata, are aggregated into spherical 

 masses. The grains are very small, and the spherical masses are not 



