468 



NA TURE 



[March 29, 1877 



the remains of an untnown inscription represented by only a few 

 of its numerous letters, each of which occupies its proper rela- 

 tive position to the known and unknown letters of the inscrip- 

 tion. This is hardly a happy simile as the relative ages of the 

 beds and strata containing vegetable remains, scattered over the 

 world, are certainly very far from settled, and their correlative 

 sequence is in numerous instances still the subject of great dis- 

 cussion. The relative position of these letters is therefore at 

 present but vaguely known. 



Haeckel supposes " that the sub-marine forests of the primor- 

 dial period were formed by the huge brown algee or fucoidse." 

 In the 70,000 feet of sedimentary rocks, from the Laurentian to 

 the Devonian, beds of carbon ard graphite are abundant ; the 

 only known vegetation throughout that period is of algae. So far 

 only Mr. Carruthers agrees with Haeckel ; from this point his views 

 diverge. During the period of the deposition of these 70,000 

 feet, time enough surely elapsed (if time only be required) for the 

 evolution of vascular cryptogams from algte. In the Silurian had 

 vegetation been equally fitted to resist decay, we should probably 

 have had plant evolution indicated side by side with that of 

 animals. liefore leaving the subject of algce, we must differ from 

 Mr. Carruthers, who says that if rich floras had existed, the lime- 

 stones of the Llandovery rocks at Malvern would have preserved 

 them. In these marine rocks at the most sea-weeds could be 

 expected, and limestone of whatever age do not usually preserve 

 such traces ; but we know that floras existed by the carbon and 

 graphite before-mentioned. 



Mr. Carruthers urges what he considers as fatal objections to 

 the doctrine of evolution ; his arguments may be briefly stated 

 as follows : — 



1. The simultaneous appearance of the three principal groups 

 of vascular cryptogams, even in a more highly organised condi- 

 tion than their living representatives. 



2. The early appearance of gymnosperms and the want of con- 

 necting links between these and the lycopods from which they 

 are supposed to have been developed. 



3. The early appearance of monocotyledons. 



4. The sudden appearance of dicotyledons, not only in the 

 lower form as Apetalse, but also as Dialypetalse and Gamopetalse. 



5. The persistence in specific character of Salix polar is from 

 the glacial period until now and over a wide range. 



Let us now see on what facts these objections are founded, 

 and whether the facts are not open to other interpretations. 



1. The evolution theory requires that lower groups have de- 

 veloped until the amount of organisation was reached required 

 to enable them to fulfil the conditions under which they live, 

 and to occupy vacant ground in the economy of nature. This 

 required amount of development may be more or less quickly 

 attained, and the development of the organism then remains 

 almost stationary. Side by side with this development, other 

 development goes on unceasingly, leading to the gradual evo- 

 lution of entirely different and more highly organised forms. 

 The cryptogams are paralleled amongst vertebrates by the early 

 and specialised development of reptilia ; amongst Crustacea by 

 trilobites, &c. In like way the tetrabranchiate cephalopods, 

 the brachiopods, and numerous other mollusca,- whose hard 

 shells resisting decay, have enabled us to trace their life history, 

 have come down to the present time, just as these vascular crypto- 

 gams have, not in their most complex and differentiated forms. 

 We do not expect to find sustained progressive development in 

 the lower animal and vegetable groups, and are not surprised at 

 evidence of actual reversion. 



2. On their first appearance "the Gymnosperms do not," Mr. 

 Carruthers says, "present a generalised type, but a remarkable 

 variety of genera and species, all as highly differentiated as any of 

 the existing forms." Now if this is absolutely the case, and their 

 Hrst appearance in life is coincident with their first appearance in the 

 fossil record, there is no doubt that they were specially created, and 

 there is no need of further argument. But the point not yet proved 

 is that the two are coincident. The occurrence of coniferse in the 

 Devonian is only known by wood with coniferous structure. 

 The fruit and foliage, if known, might possibly afford an indica- 

 tion of the mode in which their course of evolution, as suggested 

 by Haeckel, had taken place. Unger has described anomalous 

 woods from Thuringian recks of Devonian age. " Had these 

 been of earlier age than Miller's Cromarty wood they might h:.ve 

 been looked upon as one of the steps leading up to the true 

 Coniferous structure." These may yet be looked on as steps, 

 for the relative age of these Devonian rocks is still to be fixed. 

 This occurrence of anomalous wood is at all events not to be 

 overlooked, if, as is stated, the gymnosperms both structurally and 



embryologically form the transition group from ferns to angio- 

 sperms. The occurrence of Coniferous wood in Devonian rocks 

 rather shows how great are the gaps to be filled up, and that the 

 evolution of the gymnosperms commenced at an earlier period than 

 was supposed, during the formation of the great carbon layers 

 of the older rocks, and side by side with the development of ferns 

 and lycopods. The common ancestors of the spore-producing 

 lycopod and the seed-bearing gymnosperm are to be sought in 

 remoter times even than the Devonian. There is no evidence that 

 the Devonian woods were those of the higher and dioecioug 

 conifers and that conifers first appeared in this form. Little is really 

 known of the earlier coniferje, but the cycads — the lowest form, 

 and most nearly allied to ferns — were far more abuadant formerly 

 than at present. Schimper writes as follows : — " What form the 

 prototype of our conifers took in carboniferous times is not satis- 

 factorily settled, neither fruit nor foliage having been discovered 

 which could be placed in any order with certainty. The few 

 fragments placed in Abietinse may belong to Lepidodendron."^ In 

 the Permian rocks conifers are abundant. 



3. Concerning the appearance of Monocotyledons at the base 

 of the Tiias, the first true monocotyledon, Mr. Carruthers states, 

 is the stem and spike of an aroideous plant from the lowest carbo- 

 niferous strata near Edinburgh. 2 Recently a number of addi- 

 tional specimens have come to light, but Mr. Etheridge, 

 junior, who is referred to by Mr. Carruthers as having found 

 them, does not we believe regard them to ba monocotyledons 

 at all ; and in this view, although we have not examined 

 them, we are inclined to concur, because it seems unlikely 

 that so many spikes should be found without foliage. In the 

 Transactions of the Botanical Society of Edinburgh, vol. xii. 

 p. 152, Mr. Etheridge points out that the stem of Pothocites was 

 branched, and what was thought by Paterson to be the remains 

 of a deciduous spathe was one of a series of small enlargements 

 which " occur along the course of the stem at regular intervals, 

 jutting out one on each side opposite one another." This addi- 

 tional information throws still greater doubt on the correctness of 

 the determination. At Bournemouth, where aroids are abundant, 

 leaves only have been found without a single spike. This is not 

 the first time monocotyledons have been supposed to be present 

 in the Carboniferous ; for example, Cordaites, a plant now acknow- 

 ledged to be a gymnosperm — but whether a cycad or conifer is 

 still, according to Schimper, a matter of doubt — was formerly 

 supposed to be a palm, and subsequently a Yucca or Dracaena. 

 The curious twisted bodies called Spirangium are assumed to be 

 monocotyledons on very slender grounds, their affinities, accord- 

 ing to high authorities, being completely unknown. Neverthe- 

 less we find Mr. Carruthers, referring to the Carboniferous, 

 says : — " Including these fruits there are probably eight species 

 of monocotyledons in the later Palaeozoic rocks." But excluding 

 them there is but one, and that, as just shown, of an extremely 

 doubtful nature. Monocotyledons occur doubtfully in the Trias 

 as Yuccites, and in many forms in the Lias, agreeing so far with 

 Hacckel's table of their pedigree. They gradually increase in 

 number until the present day. Although we question the reality, 

 we think the early appearance of a monocotyledon, even if it had 

 occurred, would no more invalidate the theory of evolution 

 than does the equally unlooked-for occurrence of mammalian 

 remains in secondary rocks, invalidate the theory in reference to 

 animal remains. 



4. The next point Mr. Carruthers brings before us is the ap- 

 pearance of dicotyledons, and as their testimony for or against 

 evolution is very important, this testimony deserves examination 

 at some length. Mr. Carruthers regards, as the most fatal objec- 

 tion to the evolution theory, the supposed fact that representatives 

 of all the three great groups appear simultaneously in the Upper 

 Cretaceous rocks. Dicotyledons have been found as low down 

 as the Neocomian, and their discovery in rocks of this age is 

 quite recent. Still the evidence that this is their earliest ap- 

 pearance is purely negative, and no hypothesis is satisfactory 

 which is based entirely on negative evidence. It is probable - 

 that dicotyledons may be found in yet earlier rocks — perhaps .| 

 quite early, although playing an extremely subordinate part. 

 The Wealden has yielded no monocotyledons, yet we know that 

 they must have existed ; may not then the earlier forms of 

 dicotyledons also have existed ? We may parallel the case of the 

 mammals from the Purbecks. The Purbeck fauna was considered 

 to show no trace of mammals until the examination of a particular 



' Pinus anthracina, Lindley and Hutton, is " certainly a fragment of 

 Lepidodendroid fruit." — Carr., Geo!. Mag., vol. ix. p. 58. 



- Pothocites grantoiti, Paterson. Trans. Bot. Soc. Edinb., vol. i. p. 45, 

 pi. 3, f. 1-3. Not mentioned by Haeckel or Schimper. 



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