Pammel — Anatomical Characters of Seeds of Leguminosae. 127 



stem. The mucilage produced at the tip of the aerial roots 

 of corn DO doubt helps to fasten them to the ground (367). 

 In none of these cases can the mucilage be compared with 

 that found in Leguminosae. It has been suggested that the 

 mucilage in Loranthus and Viscum is a water reservoir (400, 

 85). That it may also serve the same purpose in leguminous 

 seeds can hardly be doubted. When once the water passes 

 the Malpighian cells and reaches the endosperm the latter has 

 a great affinity for it and additional amounts are taken up 

 readily. In this respect it may be compared with the muci- 

 lage cells of succulents (452. 463). After the endosperm 

 has taken up water the aleurone layer secretes a ferment 

 which dissolves the cell-walls, and the soluble material is 

 conveyed to the embryo. 



Embryo. 



The embryos of the seeds of our Leguminosae are extremely 

 variable from a structural standpoint. In the common food 

 Leguminosae, e. ^., Pisum, Vicia, and Phaseolus, the outer 

 row of cells is somewhat elongated. The outer walls are 

 thickened and with no intercellular spaces between the cells 

 of the first row. The cells below are larger, with small inter- 

 cellular spaces at their angles. In Phaseolus multijlorus the 

 structure is essentially the same except that the cell-walls of 

 the interior are provided with pores. The intercellular spaces 

 are large. In many of the Phaseoleae there are several rows of 

 elongated, palisade-like cells on the superior face. In Pisum 

 they are absent from both the inferior and superior faces. 

 In others the cells below are spongy. The spongy structure 

 makes the seed light so that it can easily float (Buchwald 35). 

 Van Tieghem (274. 275) also cites similar cases. In Astra- 

 galus canadensis the outer row of cells is considerably smaller, 

 the outer walls are thickened, the cells within are much 

 longer with small intercellular spaces. The character and 

 form of these cells are shown in Table G. The micro- 

 chemical reactions of cell-walls and contents are shown in 

 Table E. 



The reserve material varies not only in tribes but in related 

 genera. In general, however, tribes are quite constant. In 



