Sept. 7, 1876] 



NATURE 



391 



Von Mohl onwards, if they have not succeeded in showing 

 that <?// plant tissues are cellular. Coming to details, it is a 

 little surprising to find (p. 87) sieve tubes {siebrohreti) con- 

 fused with dotted ducts {poren^efassc) ; the two structures 

 are entirely distinct and are characteristic respectively of 

 the " bast " and " wood " tracts of the fibro-vascular 

 bundle. It is remarked that the " latticed cells of some 

 authors are of a similar nature ; " but the real fact is that 

 they are the same thing. Hartig, who discovered the 

 sieve-tube? in Cuctirbita, found the pores open and occu- 

 pied by threads of protoplasm which united that of 

 adjoining cells ; Von MohJ, doubting this, proposed for 

 them the name oi gitierzellen, so as to avoid the implica- 

 tion of perforation. Under the head of substances found 

 in cells, we have, of course, an account of starch, sugar, 

 gum, &c. The very important fact that starch grains are 

 always formed in protoplasm, which is also the agent in 

 their eventual solution, is overlooked. Gum, also, is not 

 usually found in cells at all ; it is the result of a muci- 

 laginous change of the c^-ivalls. 



Next in order would come an account of the principal 

 systems of tissues— epidermal, fundamental, and fibro- 

 vascular. Prof. Balfour treats of the former alone, only 

 recognising a classification of the tissues of the plant into 

 an outer layer bounding an inner mass. This leads him 

 into numerous difficulties. Thus he calls the velamen of 

 the aerial roots of orchids (which is a development of the 

 epidermis), hypoderma, although that is a modification of 

 the fundamental i.e.^ as the name indicates, sub-epidermal 

 tissue. Again, he derives cork from the epidermal layer, 

 whereas it is almost always developed from cortical tissue 

 under the epidermis, which is usually destroyed at the 

 time of its production ; lenticels, also are connected with 

 cork- formation, and not, as Prof. Balfour states, with the 

 development of aerial roots. It may be noted, also, that 

 the popular theory of the action of stomata still keeps its 

 place here, although long ago shown to be as often as not 

 untrue. 



The remainder of the article deals with the morphology 

 of flowering plants with brief and utterly insufficient refer- 

 ences to other groups lumped together under the general 

 head of Cryptogams. Prof. Balfour is equally fond of the 

 classification of plants into Dicotyledons, Monocotyledons, 

 and Acotyledons, of which the value at the present time may 

 be estimated by the fact that it was proposed by Jussieu 

 in 1789, and is about as significant now as a classifica- 

 tion of religions would be into Unitarians, Christians, and 

 Heathen. Neither here nor elsewhere is there any grasp 

 of general principles to relieve the arid monotony of tech- 

 nicalities often unfortunately inaccurate. A few instances 

 of this may be noted : — The rhizome of Solomon's seal 

 (p. 98) is a typical instance of a definite {sympodiitm), not 

 of an indefinite rhizome {monopodiuin) ; the stem of the 

 Shola plant is not wholly composed of pith (p. 100), but of 

 a peculiar kind of wood ; the dark bands in the trans- 

 verse section of the tree-fern (Fig. 89) are not woody 

 fibres, they do not belong to the fibro-vascular, but to the 

 fundamental system ; on p. 92 we are told that the group 

 of Thallogens comprise Algas and Fungi, while on p. 107 

 we find added " and many Hepaticae " — nothing more 

 being really meant than that they have a thalloid habit ; 

 lastly, not to prolong the citations interminably, we are 

 told on p. 119 that "the absorption of carbonic acid 



water and other fluids is carried on by the leaves, chiefly 

 by the stomata," whereas it is pretty generally believed 

 that the business of leaves is to get rid of water, not to 

 take it in. 



One feature of Prof. Balfour's article cannot fail to 

 strike even the most casual reader. This is the extra- 

 ordinary profusion of technical terms made still more 

 repellent by catching the eye, in italics. Here are some 

 specimens : — 



" The names of boihrenchyma and iaphrenchyma have 

 been given to a tissue composed of such cells. Not un- 

 frequently contractions are visible on the outside of the 

 vessel, indicating its formation by coalescence of super- 

 posed cells. To vessels exhibiting contractions of this 

 kind, whether spiral or pitted, the terms motiilifortn or 

 vermifor))i have been applied ; and the tissue composed 

 of these moniliform vessels has been denominated phle- 

 boidal" p. 87. 



^'^ ThQ parenchyma of the leaf is the cellular tissue sur- 

 rounding the vessels, and inclosed within the epidermis. 

 It has sometimes received the names of diachyma, nieso- 

 phyllum, and diploe" p. 108. 



Now it will seem almost incredible to say that all but 

 one of the terms italicised in the passages just quoted 

 are absolutely obsolete. Science is like nature ; each 

 stage in the progress of either is furnished with appro- 

 priate belongings and surroundings, which pass away for 

 the most part, and give place to new. Literature pre- 

 serves their remembrance in the one case as the safe 

 keeping of the rocks does in the other. Science has its 

 fossils as geology has, and if we delve after them into the 

 debris of the past, it is to learn that the history of either 

 has been continuous, and not to inform ourselves of the 

 actualities of the present. But Prof. Balfour's article is 

 like a breccia to which deposits of every age have sent ill- 

 assorted contributions, and the waifs and strays of to-day 

 have to settle down as best they can with the most 

 ancient and singular remains. No botanist who is 

 engaged in solving actual botanical problems — the exist- 

 ence of which readers of Prof. Balfour's article will 

 hardly suspect — talks about phleboidal bothrenchyvia 

 or diploe any more than he thinks of calling a wal- 

 nut a Tryma, or a grape a Nuculanium. Students 

 bent on passing examinations may perhaps persuade 

 themselves, if not their examiners, that in committing 

 such hard words to memory they are making solid addi- 

 tions to their mental furniture. But the real fact is that 

 such things are of no use to anybody, and Mr. Bentham, 

 than whom no living botanist has written more systematic 

 works, has included all the terms — mostly extremely simple 

 — with their definitions which are really needed for the 

 purpose of describing plants, in a short pamphlet of some 

 thirty pages. So that while Prof. Balfour has not suc- 

 ceeded in giving us — what it is the business of an Ency- 

 clopedia article to do — a comprehensive view of the 

 broad facts of Vegetable Histology and Morphology in 

 their present aspect, he has certainly not given an account 

 of their terminology which does the subjects justice, but 

 has produced a sort of terminological cemetery in which 

 all kinds of decaying language have been affectionately 

 embalmed. 



The unfortunate result of this kind of treatment of the 

 subject — and it is but fair to admit that Prof. Balfour is 



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