424 TRANSACTIONS AND PJtOCEEDINGS OF THK [Sess. lxviii. 



but concealing within it a small budding shoot, the tip of 

 which just touched its lower end. 



If we conceive the plant of Di'osera as consisting essentially 

 of an axis bearing numerous nodes which give origin to 

 organs variously modified according to their position on 

 the axis, we see in the cauline type a great elongation of 

 the internodes, through which the true leaves are removed 

 from the surface of the ground and distributed at wide 

 intervals along the stem. This arrangement of the leaves 

 is in strong contrast with that seen in the rosette-forms 

 with bulbs in which the axis is so contracted that all the 

 leaves lie spread out flat in close contact with the ground. 

 It may be supposed to be advantageous to the plant to 

 have its leaves exposed in this way, whether for the 

 exercise of the ordinary functions of the leaf, or for the 

 capture of insects ; while a converse advantage is secured 

 by the use of the leaves as prehensile organs, through 

 which it adheres to the branches of other plants, supporting 

 its weak stem by that means, as in D. macrantha, for 

 example, which is sometimes to be seen rearing its raceme 

 of large white flowers erect above shrubs several feet high. 

 An advantage of even greater importance, in a climate 

 subject annually to a long dry season, is gained in 

 the extension of the root downwards, which gives to the 

 plant additional security against drought. This is effected 

 by an expansion of the internodes of the shoot sent down 

 from the rootstock for the regeneration of the bulb, as 

 described above, the short pedicel of the rosette-forms 

 being extended into an organ that places the new bulb in 

 a deeper position, where it will be less exposed to the 

 chance of desiccation. The habit of prolonging the axis 

 downwards in this way is mostly seen in the cauline type, 

 but not exclusively so ; while, on the other hand, in the 

 climbing D. macrantha, the new bulb is formed separate 

 from the old, and diverging at an angle, as is the case 

 in the Orchidcie. 



