THE FUNDAMENTAL TISSUE. lO:? 



the fibro-vascular bundles often contain parenchyma also, and -vice I'ersa, the fundamental 

 tissue is not always parenchymatous but sometimes distinctly prosenchymatous. We 

 have, moreover, to deal here not with forms of cells, but with the contrast of different 

 systems of tissue, each of which may contain the most various cell-forms. I must com- 

 pare somewhat more closely my description and use of terms with those of Nageli. It 

 might be supposed that Nageli's Protenchyma is synonymous with my fundamental tissue- 

 but this is not the case; the protenchyma of Nageli is a much more comprehensive idea' 

 everything which I call fundamental tissue is protenchyma ; but all protenchyma is not 

 fundamental tissue.^ Nageli ^ says, for example, that he would call the primary meristem 

 and all parts of the tissue which arise immediately from it (/. e. only through the medium 

 of secondary meristem, but not of cambium) Protenchyma (or Proten) ; the cambium 

 on the other hand, and everything which directly or indirectly originates from it Epen- 

 chyma (or Epen). When Nageli thus defined these terms, he was dealing with a de- 

 scription of fibro-vascular bundles, and it is intelligible that he on this occasion included 

 everything which does not belong to the fibro-vascular bundles under one common name 

 (Proten). But our business is to give a uniform description of the various differentiations 

 of the tissues of plants ; and there is no reason for bringing into prominence only the 

 contrast between fibro-vascular and non-fibro- vascular masses (Epenchyma and Proten- 

 chyma), and for considering as less important the other differentiations ; the proten- 

 chyma of Nageli therefore splits up, according to me, into three kinds of equal value 

 with his epenchyma. The primary meristem is as completely opposed to the fibro- 

 vascular masses as to the epidermal and fundamental tissues, for the three systems of 

 tissue arise by differentiation out of the still undifferentiated primary meristem. The 

 conception of Proten, after the primary meristem has been eliminated from it, might be 

 applied equally to the epidermal and the fundamental tissues ; but I see no reason which 

 compels us to bring into prominence this contrast alone ; nature rather indicates that the 

 differentiation between epidermal and fundamental tissues is as essential as that between 

 fibro-vascular bundles and fundamental tissue. From all this it follows that primary 

 meristem, epidermal tissue, fibro-vascular bundles, and fundamental tissue are concep- 

 tions of equal value ; in each of the three differentiated tissues we find the most various 

 forms of cells; and secondary meristem may also arise in each. Tn the fibro-vascular 

 bundles the cambium is of this nature, the whole of the young epidermis is a generating 

 tissue in as accurate a sense as the cambium ; if this latter forms vessels, wood, bast, 

 &c., the former produces hairs, stomata, prickles, &c. The phellogen, belonging to the 

 epidermal system, arises still more decidedly as a generating tissue ; finally even in the 

 fundamental tissue a portion may persist for a considerable time as generating tissue, 

 or may subsequently produce such a tissue [e. g. the meristem of the stems of Dra- 

 caena), which brings about its increase in thickness and thus forms new fibro-vascular 

 bundles. 



(b) Examples. The relationship of the three systems of tissue may be observed very 

 simply and undisturbed by subsequent new formations in the foliage-leaves of Ferns and 

 of most Phanerogams ; in these the fundamental tissue is generally the prevailing system, 

 and is developed into different cell-forms. Isolated fibro-vascular bundles separated by 

 the fundamental tissue traverse the leaf-stalk, and are distributed through the blade ; in 

 the former they are generally surrounded by a broad-celled thin-walled parenchymatous 

 fundamental tissue extended axially ; this also forms sheath-like envelopes around the 

 stronger bundles of the blade, which are conspicuous on the under-side of the leaf as the 

 Veins ; but the finer branches, and the finest of all, run through the so-called mesophyll, 

 i. e. a peculiar form of the fundamental tissue distinguished by containing chlorophyll and 

 by its thin cell-walls. Not unfrequently single cells of the fundamental tissue of the leaf- 

 blade assume very peculiar forms {e. g. the larger stellate cells in the leaf of Camellia 



^ See his Beitriige zur wissenschaftlichen Botanik, Heft i, p. 4. 



