Pammel — Anatomical Characters of Seeds of Leguminosae. 115 



thickened. The arillate rim in Mucuna pruriens consists of 

 thick-walled sclerotic cells which graduallv mero;e into the 

 thinner-walled epidermis. Between the epidermal cells and 

 the parenchyma sheath occur thin-walled parenchyma cells 

 somewhat elongated in the direction of the vascular bundle. 



Before maturity the epidermal cells contain a nucleus, 

 cytoplasm with its chlorophyll grains, starch, sugar and aspar- 

 agin. Dahmen found calcium oxalate rather common, and 

 according to his observation it is rather intimately connected 

 with the formation of cellulose. It accompanies or occurs in 

 combination with a salt of calcium, e. g., calcium glycose. 

 Asparagin is common during the ripening process of the seed 

 in the parenchyma cells of Mucuna. 



The funiculus is the channel through which the ovule and 

 the developing seed receive their nutrient material, but the 

 vascular elements, according to Dahmen, are not the only 

 channels, as this function may be carried on by the spongy 

 parenchyma and the epidermis. From the funiculus the elab- 

 orated products are conducted into the seed by way of the 

 tracheid island. That these substances also pass laterally 

 through the undeveloped Malpighian cells is highly probable. 

 From the tracheid island they can readily pass down, and then 

 tangentially towards the nutrient layer. The elongated, 

 thin-walled parenchyma cells lead directly to the nutrient 

 layer. 



The functions of the different parts of this region in the 

 mature seed have been made the subject of papers by Matti- 

 rolo and Buscalioni (174), and Pfaefflin (199), who have 

 shown that water passes through the hilar groove; but the 

 latter has found this to be limited. Water passes in readily 

 through the micropylar opening. The Pfaefflin experiments 

 show that the Malpighian cells next to the micropyle take up 

 the greatest amount of water. It seems pretty well demon- 

 strated from the above experiments that the micropyle is 

 hygroscopic in its character, opening and closing according to 

 external conditions. The hilar groove is also hygroscopic. 

 The radicle occurs in a pocket, and is in close proximity to the 

 micropyle. Exchange of gases is accomplished more readily 

 through the micropyle than through the tracheid island. 



