CLIMBING PLANTS. 685 



and revolves in the manner described above. That which is performed by the 

 naked protoplasm of a cilium may also be accomplished by the association of 

 protoplasmic masses in the simple cell-filament of an oscillatoria-thread, and 

 nothing contradicts the supposition that also in those extensive cell-aggregates 

 which compose the shoot of a twining plant, the progressing, opposed strains, 

 which appear as revolving movements in the shoot, occur in like manner. Why 

 should not one portion of the masses of protoplasm, associated together and 

 co-operating harmoniously for the welfare of the whole plant, perform that work 

 which is accomplished in minute unicellular plant-organisms by an extended 

 protoplasmic thread? Is it not simplest to suppose that the living protoplasm 

 of certain rows of cells on the circumference of the shoot should effect the 

 elongation and contraction, the advancing opposed strains above described, in a 

 word, the twining movement of the whole shoot-apex? What it is that impels 

 the protoplasm to this work is just as puzzling as the stimulus to the production 

 of partition- walls in the interior of a cell, or the motive to those wonderful ac- 

 cumulative and divisional processes in the protoplasm of the Myxomycetes described 

 on p. 572. We know, indeed, that these processes, which depend on the dis- 

 placement of the ultimate particles of the protoplasm, are possible only under 

 certain external conditions, but it cannot be asserted that external conditions 

 definitely shape and direct the work done by the protoplasm. 



In a number of twining plants, e.g. the Hop, Honeysuckle, and the twining 

 Polygonum {Hwmulus Lupulus, Lonicera caprifolium, Polygonum convolvidui^), 

 the shoots turn round from the east through the south towards the west, 

 which is termed turning to the right (dextrorse or clockwise). Others, again, as, 

 for example, the Scarlet-runner, the bindweeds, and various species of birthwort 

 (Phaseolus muUiflorus, Convolvulus sepium, Aristolochia sipho), turn round 

 from the east through the north towards the west, and this is termed turning 

 to the left (sinistrorse or counter-clockwise). External conditions have no 

 influence on the maintenance of these directions. It is a matter of indifference 

 to the direction of these movements whether we allow light, warmth, and 

 humidity to operate on this side or that; the particular species always twists 

 in the same direction, the Hop towards the right, the Scarlet-runner towards the 

 left. More than this, even if the twining portion is continuously bound in an 

 opposite direction, the result is all the same; the plant cannot be coerced into 

 any other path, and will not depart from the direction peculiar to it. It continues 

 to twist and twine according to an innate tendency inherited from generation to 

 generation, and we can only refer the different directions of twisting to internal 

 causes, to the peculiar constitution of the living protoplasm in each particular 



plant. 



However puzzling the ultimate causes of this torsion may be, the end to be 

 attained by these revolutions of growing shoots is patent enough. That it may 

 twine upwards a shoot requires an erect support, with which it must come into 

 contact almost at a right angle. If such a support exists in the immediate neigh- 



