PIIANEROGAMIA : AXIAL ORGANS. 235 



dition, while one or more of the lowest lateral buds grow on, and 

 horizontally beneath or above, the surface of the soil, without ever 

 erecting themselves, the axes proceeding from their lateral buds alone 

 rising up free into the air. These horizontal axes proceeding from 

 lateral buds, I name, exclusively, root-stocks or rhizomes (rhizoma). 

 Examples are found in Pteris aquilina, Equisetum arvense, Phr ay- 

 mites communis, Carex arenaria, Gratiola officinalis (?), Dentaria 

 lulbifera (?), &c. 



The buds have to be treated at length hereafter ; here merely the for- 

 mation of axes was in question. On the relation of lateral parts (here 

 the secondary axes) to an axis (here the main axis), what is requisite 

 has already been stated and remarked in the General Morphology, as the 

 forms arising out of it denote nothing exclusively botanical. Here it was 

 merely necessary to mention what laws of development the varieties may 

 depend upon. Very important it was, accurately to define the concep- 

 tion of a true rhizome, since, heretofore, the word has been so played 

 with, that pretty nearly every possible part of a plant that ever is subter- 

 raneous has been understood by it, and at last no one knows what a rhi- 

 zome really is, although the word is in general use. I think it is conve- 

 nient to define and restrict the expression as in the paragraph. By this 

 we shall have a name for a definite peculiarity in the mode in which 

 many plants survive for a number of years, which certainly deserves a 

 special name. The development of the rhizome is easiest to trace in 

 germinating Asparagus. The systematists will object that they cannot 

 begin with such distinctions in their dried plants. I cannot help them. 

 The living plant is the object of our science, not the hay which we pre- 

 serve as a miserable make-shift in our blotting paper ; and a living, 

 scientific principle, like the history of the course of development, can 

 alone give Botany a value. Many, indeed, there may be to whom Botany 

 is nothing but the science of the Herbarium : with these I have no 

 concern. 



d. Of the Structure of Axes. 



129. Like all other parts of a plant, every axis, in its earliest 

 condition, is composed of cellular tissue ; in this are gradually 

 formed the vascular bundles, closed or unlimited (see 26.). This 

 is common to all Phanerogamia. I know of no Phanerogamous 

 plant (except Wolffia Hork.*) without vascular bundles (even if 

 without vessels. 26.). 



Besides these, are formed, in different arrangements in different 

 plants ( 27.), liber-cells, sometimes as bundles, sometimes as a 

 closed ring, or scattered singly in the parenchyma, intermediate 

 forms between liber and parenchyma ( 27.), sometimes isolated, 

 sometimes in bundles ; milk-vessels ( 27.), and reservoirs for pe- 

 culiar secretions ( 24.), spiral-fibrous and porous cells ( 18.), in 

 groups or scattered; lastly, air canals and cavities ( 24.), the 

 former frequently regularly arranged, especially in aquatic and 

 bog plants, the latter mostly occupying the axis of the internodes, as 



* JFolffiii Mlclich'i mihi = Lemna arrhiza Micheli. W. Deliki tnihi = Lennirt Jti/nJlna 

 Delile. 



