4 BOTANICAL GAZETTE [jm.v 



cells are thin-walled, and are much distorted in shape. The endo- 

 sperm is represented by a thin pellicle, usually two cells in thickness, 

 except at the lower edge of the seed, where it thickens to form a 

 mass of appreciable thickness, which forms a cap over the free 

 end of the hypocotyl. The well developed embryo nearly fills the 

 seed. The two large cotyledons are flat, nearly circular in outline, 

 accumbent, the curved hypocotyl lying closely against the edges of 

 the cotyledons, and being free only at the end. The seed, there- 

 fore, corresponds very closely to that of Dianthera nodosa Benth. 

 & Hook, as described by Schaffnit (8, p. 65). 



The epidermis of the hypocotyl is composed of small cells which 

 are elongated vertically. The cortex consists of about ten layers 

 of cells, radially arranged, and of larger diameter than those of the 

 epidermis. They are flattened vertically, and appear nearly square 

 in cross-section. The innermost layer appears in no way different 

 from the rest of the cortex. One striking feature of this layer, 

 however, is the division of its cells, on each side of the central 

 cylinder between the protoxylem poles, to form two layers (fig. 14) • 

 Schizogenous air cavities, of small diameter, but of considerable 

 length, have already formed between the angles of the adjoining 

 cells. 



The central cylinder is sharply marked off from the surrounding 

 cortex, owing to its greatly elongated cells of very small diameter 

 (fig. 14). Just below the insertion of the cotyledons, the central 

 cylinder divides to form the two procambial cotyledonary traces 



(fig- *3>- 



Germination 



The earliest stages of germination have not been observed in 

 the field. Seeds brought into the laboratory and soaked in water 

 swelled about 0.5 mm. in diameter and about 0.25 mm. in thick- 

 ness. These soaked seeds were then placed in a moist chamber, 



>n wet sand. The testa soon split, the 

 Further growth now forces upward 



hypocotyl pushing through 

 the upper end of the hypoo 



ne or both of the cotyledons. The latter 

 soon become green, continue their growth, and function photo- 

 synthetically for some time. The plumule is rather tardy i n 

 starting its growth. 



