538 



SCIENCE. 



[Vol.. 11., No. 37. 



fragments of sandslone casts of the exterior surface 

 of the bark^ being very abundant in most of the lead- 

 ing English coal-fields. Corda also figured it- from 

 Kadnitz, confounding it, however, with his lepido- 

 dendroid Sagenaria fusiformis, with which it has no 

 true affinity. Of the smaller plants of which we 

 know the structure, but not the systematic position, 

 I may mention the beautiful little Kaloxylons.'' We 

 have also obtained a remarkable series of small 

 spherical bodies, to which I have given the provis- 

 ional generic name of Sporocarpon.^ Their external 

 wall is multicellular: hence they cannot be spores. 

 Becoming filled with free cells, whicli display various 

 stages of development as they advance to maturity, 

 we may infer that they are reproductive structures. 

 Dr. Dawson informs me that he has recently obtained 

 some similar bodies, also containing cells, from the 

 Devonian beds of North and South America. Except 

 in calling attention to some slight resemblance exist- 

 ing between my objects and the sporangiocarps of 

 Pilularia,^ I have formed no opinion respecting their 

 nature. Dr. Dawson has pointed out that his speci- 

 mens, also, are suggestive of relations with the Khizo- 

 carpae. 



I am unwilling to close this address without mak- 

 ing a brief reference to the bearing of oui subject up- 

 on the question of evolution. Various attempts have 

 been made to construct a genealogical tree of the 

 vegetable kingdom. That the cryptogams and the 

 gymnosperms made their appearance, and continued 

 to flourish on this earth, long prior to the appearance 

 of the monocotyledonous and dicotyledonous flow- 

 ering plants, is, at all events, a conclusion justi- 

 fied by our present knowledge, so far as it goes. 

 Every one of the supposed palms, aroids, and other 

 monocotyledons, has now been ejected from the lists 

 of carboniferous plants, and the Devonian rocks are 

 equally devoid of them. The generic relations of 

 the carboniferous vegetation to the higher flowering 

 plants found in the newer strata have no light thrown 

 upon them by these paleozoic forms. These latter 

 do afford us a few plausible hints respecting some of 

 their cryptogamic and gymnospermous descendants, 

 and we know that the immediate ancestors of many 

 of them flourished during the Devonian age; but here 

 our knowledge practically ceases. Of their still older 

 genealogies, scarcely any records remain. When the 

 registries disappeared, not only had the grandest 

 forms of cryptogamic life that ever lived attained 

 their higliest development, but even the yet more 

 lordly gymnosperms had become a widely diffused 

 and flourishing race. If there is any truth in the 

 doctrine of evolution, and especially if long periods 

 of time were necessary for a world-wide development 

 of lower into higher races, a terrestrial vegetation 

 must have existed during a vast succession of epochs, 

 ere the noble lycopods began their prolonged career. 

 Long prior to tlie carboniferous age tliey had not only 

 made tliis beginning, but during that age tliey had 

 diffused themselves over the entire eartli. We find 



'., pi. ^ 



Memoir i 

 Memoir i 

 ' Memoir is., p. 348. 



Flora der vorvelt, tab. 



, flg. 4. 



them equally in the old world and in the new. We 

 discover them from amid the ice-clad rocks of Bear 

 Island and Spitzbergen to Brazil and New South 

 Wales. Unless we are prepared to concede that they 

 were simultaneously developed at tliese remote cen- 

 tres, we must recognize the incalculable amount of 

 time requisite to spread them thus from their birth- 

 place, wherever that may have been, to the ends of 

 tlie earth. Whatever may have been tlie case witli 

 the southern hemisphere, we have also clear evidence 

 that iu the northern one much of tliis wide distribu- 

 tion must have been accomplislied prior to tlie Devo- 

 nian age. Wliat has become of this pre-Devonian 

 flora ? Some contend tliat the lower cellular forms 

 of plant-life were not preserved, because their delicate 

 tissues were incapable of preservation. But why 

 should this be the case? Such plants are abundant- 

 ly preserved in tertiary strata: why not equally in 

 paleozoic ones? Tlie explanation must surely be 

 sought, not in their incapability of being preserved, 

 but in ths operation of other causes. But the 

 carboniferous rocks throw another impediment in 

 the way of constructors of tliese genealogical trees. 

 Whilst carboniferous plants are found at hundreds of 

 separate localities, widely distributed over the globe, 

 the number of spots at which these ijlants are found 

 displaying any internal structure is extremely few. 

 It would be difiicult to enumerate a score of such 

 spots; yet each of those favored localities has re- 

 vealed to us forms of plant-life of which the ordina- 

 ry plant-bearing shales and sandstones of the same 

 localities show no traces. It seems, therefore, that, 

 whilst there was a general resemblance in the more 

 conspicuous forms of carboniferous vegetation from 

 the arctic circle to the extremities of the southern 

 hemisphere, each locality had special forms that 

 flourished in it either exclusively, or at least abun- 

 dantly, whilst rare elsewhere. It would be easy, did 

 time allow, to give many proofs of the truth of this 

 statement. Our experiences at Oldham and Halifax, 

 at Arran and Burntisland, at St. Etienne and Autun, 

 tell us that such is the case. If these few spots which 

 admit of being searched by the aid of the microscope 

 have recently revealed so many hitherto unknown 

 treasures, is it not fair to conclude tliat corresponding 

 novelties would have been furnished by all the other 

 plant-producing localities, if these plants had been 

 preserved In a state capable of being similarly inves- 

 tigated? I have no doubt about this matter: hence 

 I conclude that there is a vast variety of carbonif- 

 erous plants of which we have as yet seen no traces, 

 but every one of which must have played some part, 

 however humble, in the development of the plant 

 races of later ages. We can only hope that time will 

 bring these now hidden witnesses into the hands of 

 future paleontologists. Meanwhile, though far from 

 wishing to check the construction of any legitimate 

 hypothesis calculated to aid scientific inquiry, I 

 would remind every too ambitious student that there 

 is a haste that retards rather than promotes progress, 

 that arouses opposition rather than produces convic- 

 tion, and that injnres the cause of science by dis- 

 crediting its advocates. 



