182 THE PLANT WORLD. 



A FEW OBSERVATIONS OF ROOT-HAIRS. 



By W. J. Beal. 



THE Yoot-lmhs of Ag?'ostenima Githar/o Z., and Silene nocf iff oj'a Z., 

 seem to come in vertical rows from the roots. Between each 

 two rows of hairs, there are two to three rows of cells that are 

 destitute of hairs. Two of the first crop of hairs as seen on Agrostemma 

 are here represented in Figure 1. At a later period or farther back 

 from the root-tip appear from other cells root-hairs that are fully 

 twice the distance of those of the first crop. Figure 2 illustrates four 

 hairs in a row mao-nified to the same extent as those in Fitjure 1. 

 These are about one-sixth as long as the narrow hairs in the same 

 vicinity. , 



On roots of Agrostemma the hairs spring each from the outer or 

 lower end of a cell as shown in Figure 3. This seems to be the rule 

 in most plants examined though the hairs on roots of Leonurus Car- 

 diaca Z., spring from the middle of the cell instead of the lower end. 

 (Figure 4.) 



The moving contents of the hairs of Zeonurus are thin and clear 

 with small, distinct grains, while that of Agrostemma is much denser 

 with a motion like thin flowing wax. 



Root-hairs are extremely delicate and sensitive, easily affected by 

 change of temperature, moisture and contact with foreign substances. 

 This is a fact well-known. In my brief and interrupted observations, I 

 could not help being impressed with the thought that where some par- 

 ticular conditions had caused one or two hairs to assume a particular 

 shape, others in the immediate vicinity were likely to closely resemble 

 them. Here on roots of wheat are numbers of hairs near each other 

 much the shape of a stocking, (5) and in another place, they are wavy 

 for most of their length, (6) and in another place groups are found 

 that are enlarged or swollen near the base (T). 



On one side of the root of Rumex C7'ispus Z., 4 mm. long, I counted 

 fourteen hairs with tips having a spherical expansion at the apex, (8) 

 and several hairs on another root were of the same shape, while others 

 were found one to three in a place like those illustrated in Figure 9. 



Roots of Plantago lanceolata Z., were seen with many many hairs 

 the shape of stockings. Some roots of Chenopodlum hyhrldmn Z., had 

 groups of hairs with expanded spherical tips. 



Root hairs of wheat are occasionally found forked, branching with 



