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pieces of stems, branches, &c., in large, darkened jars, 

 the air in which was kept constantly moist by a lining of 

 ■ivet filter paper. The cuttings were suspended both in 

 the normal position — that is with the upper end upwards 

 — and also upside down. Vochting found as a geiK-ral 

 result that there is a strong tendency for the roots to 

 appear at the basal end,' and the branches to be deve- 

 loped at the apical end, whether the cutting had been 

 hung ape.x upwards or downwards in the glass jar. 



Vochting believes that the growth of roots at the base 

 and of branches at the apex of a cutting are determined 

 chiefly by an innate, inherited, growth-tendency. When 

 the knife divides a branch into two cuttings it separates a 

 mass of identically-constituted cells into two sets, one 

 which form part of the apex of the lower cutting, and 

 another set which form part of the base of the upper 

 cutting. And under appropriate circumstances one of 

 these sets of cells might develop into roots, the other 

 into adventitious buds. Vocht holds that it is the 

 morphological positions of these sets of cells (the fa' t of 

 one being at the base and the other at the apex of a 

 cutting) which chiefly determines the course of their sub- 

 secjuent development. The idea may be expressed some- 

 what familiarly by saying that each cutting into which a 

 branch is divided is able to distinguish its base from its 

 apex, and can tell where to produce roots and buds, by 

 means of an internal impulse or morphological force 

 which is independent - of the external forces, gravitation 

 and light. 



The theory which Sachs has brought forward in his 

 paper on "Stoff und Form der Pflanzenorgane " ("Arbei- 

 ten des bot. Inst. Wiirzburg," iSSo, p. 452) is entirely 

 opposed to that of Vochting. Sachs conceives that 

 Vochting's morphological force is not an innate heredi- 

 tary impulse, but a tendency produced by the action 

 of external forces during the growth of the formative 

 cells. Thus Sachs believes that the force of gravity 

 acting on the developing cells of an organ produces in it 

 a "predisposition" or enduring impulse which manifests 

 itself in the results which Vochting ascribes to a heredi- 

 tary force- The mode in which Sachs believes gravita- 

 tion to act is interesting, not only in itself but also as a 

 modification of a theory of Du Hamel's. It is assumed 

 that difference of material is a necessary concomitant nf 

 difference of form, and that accordingly the materials 

 from which roots are formed are chemically (used in a 

 quahfied sense) different from those which supply the 

 branches. Sachs' theory supposes that the grovth of 

 roots or buds at a given place will be determined 

 by the distribution of the root- and branch-forming 

 materials, and that the distribution of these materials i^ 

 regulated by the force of gravity. The root-materi d i, 

 in a certain sense geotropic and flows downwards, the 

 branch-inaterial having the opposite tendency. But they 

 are not supposed to be simply geotropic, the tendency of 

 the root-material to flow towards the base of a branch is 

 continued after the branch has been made into a cuitin^> 

 and hung upside down, so that the root-material flows 

 upwards towards the base of the cutting, because that end 

 was originally downwards, and vice vcrsA with regard to 

 the branch-forming matter. 



The observations on the bramble, which form the 

 subject of the present paper, were carried out with the 

 object of deciding how far the natural growth of roots in 

 the bramble agrees with Vochting's or Sachs' theories on 

 the growth of cuttings. 



The long sterile shoots of the bramble are well 

 known to possess the power of rooting at their end-. 

 The terminal bud is thus protected during the winter, 

 and the store of nutriment contained in the club-li e 



' The basal end is that end of a cutting nearest to the parent plant: ilie 

 apical, is the opposite end. 



° Vochting states distinctly that gravitation and light do affect the p si- 

 tions in which organs are developed in cuttings, but he considers the iriteni.il 

 impulse as the stronger deler]iiinin» causr. 



thickened end of the branch forms a starting-point for 

 new growth in the spring. It is commonly the long 

 pendant branches growing vertically downwards which 

 reach the ground and form roots. It might therefore be 

 supposed that gravitation determines the growth of roots 

 at the lower end of the branch, just as in a cutting made 

 from an erect w-illow branch the roots grow at what was 

 originally the lower end. But observations made on 

 brambles under certain circumstances show that this is 

 not the case. When brambles grow on a steep bank the 

 majority of the branches grow down hill at once, or else 

 straggle more or less horizontally along the bank and 

 finally turn downwards. But a certain number of 

 branches grow uphill, and some of these take root at 

 the apex. When therefore we find on the same indi- 

 vidual plant some branches forming roots at the physi- 

 cally lower, and others at the upper end, we may 

 feel sure that the distribution of root growth in the 

 bramble is not determined by gravitation. We mus 

 believe that there is a morphologically directed impulse 

 which tends to the production of roots at the apex of the 

 branch, wlicther tlie direction of its growth has been 

 upwards or downwards. It is true that in the observed 

 cases the extreme end of the branches was bent so that 

 from I to 9 inches was inclined at from 1° or 3° to 5° 

 below the horizon, but it can hardly be imagined that this 

 fact influences the growth of roots at the apex ; and 

 experiment shows that it is not necessary that even a 

 single inch shoifld be inclined below the horizon. A 

 bramble branch was tied, apex upwards, to a vertical 

 Stic'-;, and was surrounded by damp moss and covered 

 with waterproof cloth ; under these circumstances a plen- 

 tiful crop of roots sprang from the terminal part of the 

 branch. This result combined with the observations 

 made with brambles growing on a steep bank seem to 

 show that an internal impulse or morphological force 

 regulates the growth of roots in the bramble. 



When a cutting is made from a bramble the only 

 development that takes place is the growth of the axillary 

 buds at the apical end of the cutting. Under certain 

 circumstances these side shoots take on a root-bearing 

 function. They are stunted in growth, being, it may be, 

 10-12 mm. in length and 3 or 4 mm. or more in breadth ; 

 they assume a peculiar club-like form, being thicker at 

 the ape>c than at the base, and are clothed with rudi- 

 mentary scale-like leaves, from among which a number 

 of relatively large roots spring forth. 



In order to determine whether the production of this 

 root-bearing type of root is determined by gravitation or 

 by a "morphological force," cuttings were made from 

 branches whose direction of growth was above the 

 horizon. Such cuttings were hung apex upwards, and it 

 was found that the most apical buds were capable of 

 developing under these circumstances into the root-bear- 

 ing type of branch. Similar rooting side-shoots are 

 produced by cuttings made from branches which have 

 grown beneath the horizon, it is therefore clear that 

 t;ravitation is not the chief determining force in this 

 form of root production. 



When the end of a branch is injured, which often 

 occurs when a bramble grows along the ground near a 

 p ithway, the most apical bud or buds grow out into 

 branches ; these may be ordinarv branches which ulti- 

 raatelv take root. Under certain circumstances, the 

 stunted club-shaped root-bearing side-shoots may be 

 developed whose whole formation is devoted to the 

 bearing of roots. It is therefore clear that the produc- 

 tion of such rooting shoots in cuttings is the same pro- 

 cess that occurs in branches iniured in a state of nature ; 

 a I rocess which enables the branch to perform the function, 

 the normal performance of which had been interfered 

 with. And this fact enables us to see in what way a 



