October i, 1896] 



jVA TURE 



5o0 



the vestiges of priniajval intercourse witli the valley of the Nik-. 

 There more clearly than in any other area wc can watch the 

 continuinis development of the germs which gave birth to the 

 higher .Kgean culture. There before the days of Phoenician 

 contact a system of writing had already been worked out which 

 the .Semite only carried one step further. To Crete the earlie-st 

 CIreek tradition looks back as the home of divinely inspired 

 legislation and the first centre of maritime dominion. 



Inhabited since the days on the first (ireek settlements by the 

 same race, speaking the same language, and moved by the same 

 independent impulses, Crete stands forth again to day as the 

 champion of the European spirit against the yoke of Asia. 



SECTION K. 



IiOT.\NV. 



QpivMNd .•\ddre.ss by D. H. Scoit, F.R.S., Honorary 



KkICI'EROFTHE JODREI.I. LaHORATORY, KOYAL GARDENS, 

 Kkw, I'RESinENT OF THE SECTION. 



Present Position of Morphological Botany. 

 The object of modern morphological botany (the branch of 

 our science to which I propose to limit my remarks) is the 

 accurate comparison of plants, both living and extinct, with the 

 object of tracing their real relationshi|)S with one another, and 

 thus of ultimately constructing a genealogical tree of the vegetable 

 kingdom. The problem is thus a purely historical one, and is 

 perfectly distinct from any of the questions with which physiology 

 has to do. 



Yet there is a close relation between these two branches of 

 biology ; at any rate, to those who maintain the Darwinian 

 position. For from that point of view we see that all the 

 characters which the morphologist has to compare are, or have 

 been, adaptive. Hence it is impossible for the morphologist to 

 ignore the functions of those organs of which he is .studying the 

 homologies. To those who accept the origin of species by 

 variation and natural selection there are no such things a.s 

 morphological characters pure and simple. There are not two 

 distinct categories of characters — a morphological and a physio- 

 logical category — for all characters alike are physiological. 

 " According to that theory, every organ, every part, colour, and 

 peculiarity of an organism must either be of benefit to an 

 organism itself, or have been so to its ancestors. . . . 

 Necessarily, according to the theory of natural selection, 

 structures either are present because they are selected as useful, 

 or because ihey are still inherited from ancestors to whom they 

 were useful, though no longer useful to the existing representa- 

 tives of those ancestors." (Laiikester, "Advancement of 

 Science," p. 307.) 



The useful characters may have become fixed in comparatively 

 recent times, or a long way back in the past. In the latter case 

 the character in question may have become the property of a 

 large group, and thus, as we say, may have become morpho- 

 logically important. 



Kor instance, parasitic characters, such as the suppression of 

 chlorophyll, are equally adaptive in Dodder and in the Fungi. 

 In Dodder, however, .such characters are of recent origin and of 

 little morphological importance, not hindering us from placing 

 the genus in the natural order Convolvulacet^ ; while in Fungi 

 equally adaptive characters have become the common property 

 of a great class of plants. 



Then, again, the existence of a definite sporophyte generation, 

 which is the great character of all the higher plants, is in certain 

 h'ungi inconstant, even among members of the same species. 



.Although there is no essential difference between adaptive and 

 morjihological characters, there is a great difference in the 

 morphologist's and the physiologist's way of looking at them. 

 The physiologist is interested in the question how organs work ; 

 the morphologi.st asks, what is their history? 



The morphologist may well feel discouraged at the vastness of 

 the work before him. The origin of the great groups of plants 

 is perhaps, after all, an insoluble problem, for the question is 

 not accessible either to observation or experiment. 



All that we can directly observe or experiment upon is the 

 occurrence of variations — perhaps the most important line of 

 research in biology, for it was the study of variation that led 

 Darwin and Wallace to their grand generalisation. Many 

 observers are working to-day in the spirit of the great masters, 

 and it is certain that their work will be fruitful in results. It is 



NO. 1405, VOL. 54] 



evident, however, that such investigations can at most enly throw 

 a side light on the historical question of the origin of the existing 

 orders and classes of living things. The morphologist has to 

 attack such questions by other methods of research. 



The embryological method has so far scarcely received justice 

 from botanists. A great deal of what is called embryology in 

 botany is not embryology at all, but relates to pre-fertilisj>tion 

 changes. Of real embryology — that is to say, the development 

 of the young plant from the fertilised ovum — there is much less 

 than we might expect. Thus no comparative investigation of 

 the embryology of either Dicotyledons or Monocotyledons has 

 ever been carried out, our knowledge being entirely based on a 

 few isolated examples. 



In the cases which have been investigated perhaps excessive 

 attention has been devoted to the first divisions of the ovum, the 

 importance of which, as Sachs long ago showed, has been over- 

 rated, while the later stages, when the differentiation of organs 

 and tissues is actually in progress, have been comparatively 

 neglected. 



The law of recapitulation (or repetition of phylogeny in onto- 

 geny) has been very inadequately tested in the vegetable kingdom. 

 Whatever its value may be, it is certainly desirable that the 

 development of plants as well as animals should be considered 

 from this point of view ; and this has so far been done in but 

 very few cases. M. Massart, of Brussels, has made some 

 investigations with this object on the development of seedlings 

 and of individual leaves. He is led to the conclusion that 

 examples of recapitulation are rare among plants. ("La 

 Recapitulation et I'lnnovation en Embryologie Vegetale," Bull, 

 lie la Soc. roy. de Bot. de Bclgiqtie, vol. xxxiii. , 1894.) 



.So far, at least, embryological research has only yielded certain 

 proof of recapitulation in a few cases, as in the well-known 

 example of the phyllode-bearing acacias, in which the first leaves 

 of the seedling are normal, while the later formed ones gradually 

 assume the reduced phyllode form. 



A less familiar example is afforded by Gunnera. Here, as is 

 well known, the mature stem has a structure totally different 

 from that of ordinary Dicotyledons, and much resembling that 

 characteristic of most Ferns. In most species of Gunnera there 

 are a number of distinct vascular cylinders in the stem, instead 

 of one only, and there is never the slightest trace, so far as the 

 adult plant is concerned, of the growth by means of cambium, 

 which is otherwise so general in the class. The seedling stem, 

 however, is not only nionostelic below the cotyledons, but in 

 this region, though nowhere else, shows distinct secondary 

 growth. Thus, if we were in any doubt as to the general 

 affinities of Gunnera, owing to its extraordinary mature structure, 

 we .should at once be put on the right track by the study of the 

 embryonic stem, which alone retains the characterislic dicotyle- 

 donous mode of growth. 



It is only in a few cases, however, and for narrow ranges of 

 affinity, that the doctrine of recapitulation has at present helped 

 in the determination of relationships among plants. Beyond 

 this, conclusions based on embryology alone tend to become 

 merely conjectural and subjective. In fact, all comparative 

 work, in so far as it is limited to plants now living, suffers under 

 the same weakness that it can never yield certain results, for the 

 question w-hether given characters are relatively primitive or 

 recently acquired is one upon which each naturalist is left to form 

 his own opinion, as theorigin of the characters cannot be observed. 

 To determine the blood-relationships of organisms it is neces- 

 sary to decipher their past history, and the best evidence we can 

 have (when we can get it) is from the ancient organisms them- 

 selves. The problem of the morphologist is an historical one, 

 and contemporary documentary evidence is necessarily the best. 

 It is paleontology alone which can give us the real historical 

 facts. 



Anatomical Characters. 



In judging of the affinities of fossil plants we are often com- 

 pelled to make great use of vegetative characters, and more 

 particularly of characters drawn from anatomical structure. It 

 is true that in many cases we do so because we cannot help 

 ourselves, such anatomical features being the only characters 

 available in many of the specimens as at present known. But 

 the value of the method has been amply proved in other cases 

 where the reproductive structures have also been discovered, and 

 are found to fully confirm the conclusions based on anatomy. I 

 need only mention the great groups of the Lepidodendreo; and 

 the Calamites, in each of which the anatomical characters, when 

 accurately known, put us at once on the right track, and lead to 



