ORGANS OF NUTRITION. 121 



young by a modified epidermis Avithout stomata, which, as we have 

 seen, is sometimes called epiblema (p. 41). Tliis epiblcma, in 

 the process of deAclopment, is also furnished with hair-like pro- 

 longations, which are commonly termed fibrils ox fibrillce (fiy. 

 232). This term fibril is, however, applied by Lindley and 

 some other botanists to the minute subdivisions of the root. 

 These fibrils (which appear to be actively engaged in the 

 process of absorption, as will be afterwards seen) are especially 

 evident upon young growing roots, and as these advance 

 in age they perish, while the tissue from which they were 

 prolonged at the same time becomes harder and firmer, so as to 

 form a more or less impermeable layer of cells. 



Roots have no leaves, and usually no buds, hence they have 

 as we have seen no provision for regular ramification , but they 

 appear to divide and subdivide according to circimistances, with- 

 out any order; while the branches of the stem have a more or less 

 symmetrical aiTangcment as already described. 



The branches of the root are thus merely repetitions of the 

 original axis from which they are developed, and grow in a 

 similar manner, and like it, are commonly furnished with no 

 other organs, — such as buds and leaves for instance, as is the 

 case Avith those of tlie stem. To this, however, there are many 

 exceptions, for although the root has no poAver of forming regu- 

 lar buds, yet adventitious buds may be formed upon its surface, 

 in the same manner as Ave huxe seen that under certain circum- 

 stances they may be produced from any parenchymatous tissue. 

 The power Avhich the root thus possesses of forming adventitious 

 buds may be obsei-^^ed in the Plum-tree, the Pyrus japonica, 

 the Moutan Paony, the Japan Anemone {Anemone japonica), 

 and many others. The latter plant exhibits this tendency to a 

 remarkable extent. Thus, if the root be observed after floAvering, 

 it Avill be found to be coAxred Avith a number of little Avhite coni- 

 cal projections, Avhich are buds in a rudimentary condition; so 

 that it may be then diA^ded into a number of pieces, each of AA-hich 

 Avill give rise to a ncAv plant if placed under faA^ourable circum- 

 stances. Again, if the trunk of a young A'igorous Poplar or 

 Apple-tree be cut across near its base, at certain seasons Avhen 

 vegetation is actiA'c, tlie roots near the surface Avill produce buds, 

 from Avhich branches Avill be ultimately formed. 



From the aboA-e general description Avhich has been giA-en of 

 the groAvth and structure of the root, Ave find that the chief 

 distinctive characters betAveen it and the stem may be summed 

 up as folloAvs: — 1st, Its tendency at its first formation to 

 dcA'elope in an opposite direction to the stem, and thus 

 withdraAv from the light. 2nd, The root does not groAV 

 throughout the entire length of its newly formed parts like a 

 stem, but only by additions near its apex. 3rd, The root of 

 Dicotyledonous Plants under ordinary circumstances has no 



