MORPHOLOGY OF THE SEEDLING 31 



Transfer the plants to moist blotting paper under a bell-glass or 

 an inverted battery jar and examine the roots at the end of twenty- 

 four hours to see along what portions their length has increased; 

 continue observations on them for several days. 



42. Root-Hairs. — Barley, oats, wheat, red clover, or 

 buckwheat seeds soaked and then sprouted on moist 

 blotting paper afford convenient material for studying 

 root-hairs. The seeds may be kept covered with a watch- 

 glass or a clock-glass while sprouting. After they have 

 begun to germinate well, care must be taken not to 

 have them kept in too moist an atmosphere, or very few 

 root-hairs wEl be formed. Examine with the magni- 

 fying glass those parts of the root which have these 

 appendages. 



Try to find put whether all the portions of the root are 

 equally covered with hairs and, if not, where they are 

 most abundant. (See also Sect. 63.) 



The root-hairs in plants growing under ordinary condi- 

 tions are surrounded by the moist soil and wrap them- 

 selves around microscopical particles of earth (Fig. 11). 

 Thus they are able rapidly to absorb through their thin 

 walls the soil-water, with whatever mineral substances it 

 has dissolved in it. 



43. The Young Stem. — The hypocotyl, or portion of 

 the stem which lies below the cotyledons, is the eai'liest 

 formed portion of the stem. Sometimes this lengthens but 

 little ; often, however, as the student knows from his own 

 observations, the hypocotyl lengthens enough to raise the 

 cotyledons well above ground, as in Fig. 10. 



The later portions of the stem are considered to be 

 divided into successive nodes, — places at which a leaf (or 



