BOTANICAL SUBJECTS. 187 



much as possible to the light, this being of the utmost importance 

 to their function. In other words, the leaves have inherited the 

 habit of avoiding each other's shade by the twisting of the stem 

 into a spiral. Naturally, this is only when the stem and branches 

 are erect, for when they are horizontal or otherwise situated, the 

 disposition of the leaves is much modified.* 



The soil branches or roots are given off irregularly because 

 their function, although on the whole similar to that of the leaves, 

 is minus the influence of light. 



The root fibrils are leaf veins, minus the mesophyl, or chlorophyl 

 cells, which are supposed to have a function connected with light. 



Root hairs absorb water, just as the hairs of the aerial parts of 

 f)lants absorb vapours of water and gases. It is more than pro- 

 bable that the pores of the soil are often filled with gases, so that 

 in this case the hairs of the roots would often come in contact 

 with gases also. 



In certain aquatic Ranunculi, we have roots proper function- 

 ing in one medium — the ooze of the bottom of the pond ; then we 

 have the root-like submerged leaves, functioning in another medium 

 — the water ; and, finally, leaves proper, functioning in a third 

 medium — the air. All three appendages are homologous. They 

 are sucking organs. 



It is not easy to escape from the conclusion that a rootlet is to 

 the main root what the petiole is to the main stem, and that the 

 sub-divisions of the rootlets correspond to the nerves and veins of 

 the leaves. In other words, as I said, we might consider the roots 

 as underground leaves, and the leaves as above-ground roots, both 

 being modified to suit the medium they grow in, and for sucking 

 in materials from those media. 



Buds are given off by -both the stem and the root. The so- 

 called flowers are not produced directly by the root, because they 

 have become organs suited to surroundings which are only found 

 in the air, and in the light, such as wind, insects, &c. Therefore, 

 they are only produced on root-buds when these come to the 

 surface and become aerial stems. 



* It is not impossible that botanists have made too much of a " fetish " of 

 phyllotaxis. 



