p 



THE FUNDAMENTAL TISSUE. 121 



(a) The whole course of my description of tissue-systems necessitates the in- 

 troduction of the idea of a Fundamental Tissue. It has, in fact, long been required ; 

 it was often necessary, in anatomical descriptions of tissues which are neither epi- 

 dermal nor fibro-vascular, to distinguish them by some common term. Many writers 

 employ the term Parenchyma in this sense, in opposition to the fibro-vascular bundles 

 and the epidermis ; but this usage is not scientific ; the fibro-vascular bundles often 

 contain parenchyma, and, 'vice 'versa, the fundamental tissue is not always paren- 

 chymatous 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 compare some- 

 what more closely my description and use of tei*ms 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 tissues which arise immediately from it 

 (/. e. only through the medium of secondary meristem, but not of cambium) Prot- 

 enchyma (or Proten) ; the cambium, on the other hand, and everything which 

 directly or indirectly originates from it, Epenchyma (or Epen). When Nageli gave 

 these definitions, he was treating 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 plant-tissues; and there is no reason 

 for bringing only into prominence the contrast between fibro-vascular and non- 

 fibro-vascular tissues (Epenchyma and Protenchyma), and for considering all other 

 differentiations as less important ; the protenchyma of Nageli therefore includes, accord- 

 ing to my use of terms, three kinds of tissue each of equal value with his epenchyma. 

 The primary meristem is not more opposed to the fibro-vascular (epenchyma) than 

 to the epidermal and fundamental tissues ; for the three systems of tissue equally 

 arise by differentiation from it. The term Proten, after distinguishing from it the 

 primary meristem, might be applied collectively to the epidermal and fundamental 

 tissues ; but I see no reason for bringing into prominence this contrast alone ; 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 epidermal 

 tissue, fibro-vascular bundles, and fundamental tissue are conceptions of equal value ; 

 in each we find the most various forms of cells ; and secondary meristem may also 

 arise in each. In 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, xylem, phloem, &c., the former produces hairs, stomata, 

 prickles, &c. ; the phellogen, belonging to the epidermal system, arises still more de- 

 cidedly 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 Draccena, 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 readily, and undisturbed by subsequent 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 petiole, and are distributed through the 



^ Beitrage zur wissenschaftlichen Botanik, Heft i, p. 4. 



2 Since the publication of the ist edition of this work, the classification of tissues here proposed 

 has been generally adopted, especially by younger botanists ; as also in the main, with some 

 deviations in particular points, by Russow, Unters. liber die Leilbiindelkryptogamen, Petersburg 1873. 



