ritter: astragalus mollissimus. 205 



but the long terminal cell wall only stains violet, while the cavity- 

 looks clear. 



Loco weed leaves (dried) absorb 9.24 per cent of water, drops of 

 water disappear when placed on them, and colored solutions (saf- 

 ranin, heematoxylin, eosin, and methylene blue) easily penetrate 

 to the cell cavity. Haberlandt says that when such structures are 

 present and the leaf is capable of absorbing much water (by 

 weight) or drops of water when put on them, or there is quick 

 penetration of colored solutions, "it is fairly safe to conclude that 

 the hairs in question represent water-absorbing organs." There- 

 fore I have concluded that these hairs function for the absorption 

 of water in the form of dew or rain. The long cell gathers the 

 moisture, the irregularities on its surface serving to keep the drop- 

 lets from running off, then the middle cell with its contents con- 

 ducts it towards the cells of the mesophyll. This middle cell has 

 very dense contents, protein especially. The water may be taken 

 along the terminal cell by imbibition, then drawn by osmosis 

 through the middle cell into the leaf. 



Cross sections of the leaflet show little difference in the upper 

 and lower halves. The hairs and stomata (about thirty per square 

 millimeter) are as numerous on one side as on the other. (Figs. 3, 

 4, and 5.) Palisade cells are arranged on either side of the central 

 portion of the mesophyll, which contains the vascular tissues. It 

 appears that the reflection of the sim from the ground is strong 

 enough to stimulate the formation of palisade tissue on the under 

 side of the leaf as well as to give light enough for the chloroplasts 

 there to function. The terminal tracheids often have enlarged 

 ends, which may serve for water storage. (Figs. 3 and 4.) A 

 section of leaf seen through a microscope with a polarizer attach- 

 ment shows only the cell walls of the hairs to look bright; nothing 

 else can be seen in the dark field, and no crystals are in this way 

 demonstrated in the leaf. The upper part of the basal cell and all 

 of the outer cell walls of the epidermis are heavily cutinized. 

 (Fig. 4.) A multiple epidermis is shown in a few places. The 

 mid vein of the leaflet consists of bast, phloem and xylem. 



The petiole has numerous bundles which supply the leaflets 

 (fig. 6), one going out of the petiole into each petiolule. 



There is a layer inside the walls of the bast fibers which stains 

 reddish violet with chloroiodide of zinc, and yellow with potassium 

 iodide-iodine. The lignified walls with both are yellow. With 

 phloroglucin these linings stain red, but a little lighter than the 

 walls. Methylene blue showed no mucilaginous modification. 



