September 21, 191 1] 



NATURE 



401 



depicted for recent plants in his account of the " Strati- 

 fication in the Vegetation of a Marsh." 



The development of a mesophytic vegetation in the shelter 

 of the marsh xerophytes makes it unnecessary to postulate 

 an obscuration of the intense sunlight by vapours, as was 

 done by Unger and Saporta for the Carboniferous period. 

 'lii'- assumption of a variety of conditions of plant life 

 within the same area helps materially to clear up the 

 difficulties presented by the somewhat incongruous occur- 

 rences met with in the petrified plant-remains. The 

 presence of fragments of Cordaites, mixed with those of 

 Catamites and Lepidodendra, in the coal-balls cannot 

 always be explained either by a drift theory or by con- 

 ceiving the fragments to be wind-borne ; but, given an 

 area of retrogressive peat above the ordinary water-level, 

 even so xerophytic a plant as Cordaites might well 

 establish itself there, its mycorhiza-containing roots being 

 well adapted for growth in drier peat. The curious occur- 

 rence of more or less concentric rings in the secondary wood 

 of the stem and roots of Cordaites may represent a 

 response, probably not to annual variations of climate, but 

 to abnormal periods of drought, which would affect the 

 upper-peat layers, but not the water-logged soil in which 

 were rooted the Calamites and Lepidodendra. 



If, as I suspect, we had in the peat deposit of the coal- 

 seam a succession of associations, we ought to find its 

 growth and history recorded by the sequence of the plant- 

 remains, very much as Mr. Lewis has discovered with such 

 signal success in our Scottish peat-bogs. That some differ- 

 ences occur in the plant-remains building up a seam can 

 be noted by a microscopic examination of the coal itself, in 

 which, as Mr. Lomax tells me, the spores of Lepido- 

 dendra occur in definite bands. But no systematic attempt 

 has as yet been made to investigate from this point of 

 view the seams charged with petrified plant debris. Before 

 tfie Shore pit, which was reopened last summer through 

 the renewed generosity of Mr. Sutcliffe, was finally closed 

 down, I obtained two series of nodules, ranging from the 

 floor to the roof of the seam, and have had these cut for 

 detailed examination. I should not, however, like to make 

 any generalisation from these isolated series, but intend, 

 during the coming winter, to investigate in the same 

 manner further series taken from large blocks of nodules, 

 which have been removed bodily so as to retain the posi- 

 tion they occupied in the seam. Though at present the 

 data are only fragmentary, there seems to be some indica- 

 tion that the plant-remains are not without some relation 

 to their position in the seam. Of course, Stigmarian 

 rootlets are ubiquitous, and in the nodules of the lower 

 part of the seam predominant, but other plant-remains 

 appear to be more frequently found at one level of the 

 seam than another. The problem, however, is very in- 

 volved, and it has become apparent that it is as important 

 to study the fine debris in which the larger fragments are 

 embedded as the distribution of these latter. Moreover, 

 attention must be paid to the stage of decomposition pre- 

 sented by the particles forming the matrix of the nodule, 

 as this varies in the lower and upper parts of a seam, very 

 much as in a peat-bed we can distinguish the lighter- 

 coloured fibrous peat from the darker layers at the base 

 of a peat-cutting. Mr. Lomax, who has a unique 

 experience of these coal-balls, informs me that he can tell 

 whether a nodule is from the top or bottom of the seam 

 by the lighter or darker colour of the matrix. The import- 

 ance of applying the methods which have been so successful 

 in elucidating the history of modern peat-deposits to the 

 investigation of the coal-seam will be clearly appreciated 

 both by palasobotanists and ecologists, and this particular 

 problem offers a striking illustration of the interdepend- 

 ence of various branches of botanical investigation. It is 

 fortunate, indeed, that the two fields of work, Paleo- 

 botany and Plant Ecology, though they have been subjected 

 to fairly intensive cultivation, have not become exclusively 

 the domain of specialists. The strength and progre-- of 

 modern Botany have been due to the close collaboration 

 of workers engaged in different branches of botanical 

 science, and the fact that British ecologists have combined 

 to attack a series of the problems from verv diverse points 

 01 view leads one to hope that, with a continuance of 

 that intimate cooperation which has characterised their 

 work so far, and with the added stimulus of the friendly 



NO. 2l86, VOL. 87] 



visit of our distinguished colleagues from abroad, con- 

 siderable progress may be expected in the future in this 

 branch of botanical study. Privileged as I have been to 

 assist at the deliberations of the British ecologists, with- 

 out as yet having taken any active part in their work, I 

 feel myself at liberty to point with appreciation to the 

 excellent beginning they have made of a botanical survey 

 of Great Britain and Ireland, as well as to the more 

 detailed investigations of special associations and forma- 

 tions, such as the woodlands, the moorlands, the fens, the 

 broads, salt marshes, and shingle beaches. I am glad to 

 think that our foreign visitors have been able to see these 

 interesting types of vegetation under the guidance of those 

 who have made a special study of these subjects. 



The importance to ecologists of an up-to-date critical 

 Flora was dwelt upon by my predecessor in this presi- 

 dential chair, and this obvious need may be regarded as a 

 further illustration of the inter-relationship of the various 

 aspects of Botanical Science. Though it has been obvious 

 to all that the swing of the pendulum has been for a long 

 time away from pure systematic botany, I am convinced 

 that the great development of plant ecology, of which we 

 have many indications, will not merely lessen the 

 momentum of the swinging pendulum, but will draw the 

 latter back towards a renewed and critical study of the 

 British flora. That a revival of interest in systematic 

 botany will come through the labours of those who are 

 engaged in survey work and other forms of ecological 

 study, is foreshadowed by the fact that Dr. Moss has 

 undertaken to edit a " New British Flora," which will, I 

 believe, largely fulfil the objects put forward by Prof. 

 Trail in his Presidential Address. I trust, however, that 

 in addition to the ecologists, those botanists who are 

 interested in genetics will contribute their share towards 

 the completion of our knowledge of critical species, varie- 

 ties, and hybrids, all of which offer such intricate problems 

 alike to the systematist and to the student of genetics. 



De Vries prefaced his lectures on " Species and Varie- 

 ties, their Origin by Mutation." with the pregnant sentence : 

 " The origin of species is an object of experimental in- 

 vestigation," and this is equally true of the study of the 

 real and presumptive hybrids of our British flora, which 

 may be investigated either synthetically or, when fertile, 

 also analytically, as in some cases their offspring show 

 striking Mendelian segregation. Some good work has 

 already been accomplished in this direction, but more re- 

 mains to be done, and we have here an important and 

 useful sphere of work for the energies of many skilled 

 plant-breeders. 



I would therefore like to plead for intimate collabora- 

 tion between all botanists, hopeful that, as progress in the 

 past has come through the labours of men of wide sympa- 

 thies, so in the future, when studies are bound to become 

 more specialised, there will be no narrowing of interests, 

 but that the various problems which have to be solved 

 will be attacked from all points of view, the morpho- 

 plogical, the physiological, the ecological, and the 

 systematic. Thus by united efforts and close cooperation 

 of botanists of all schools and of all countries we shall 

 gain the power to surmount the difficulties with which our 

 science is still confronted. 



SUB-SECTION K. 



AGRICULTURE. 



Opening Address by W. Bateson, M.A., F.R.S., 

 Chairman of the Sub-section. 

 The invitation to preside over the Agricultural Sub- 

 section on this occasion naturally gave me great pleasure, 

 but after accepting it I have felt embarrassment in a con- 

 siderable degree. The motto of the great Society which 

 has been responsible for so much progress in agricultural 

 affairs in this country very clearly expresses the subject of 

 our deliberations in the words " Practice with Science," 

 and to be competent to address you, a man should be well 

 conversant with both. But even if agriculture is allowed to 

 include horticulture, as may perhaps be generally conceded, 

 I am sadlv conscious that my special qualifications are 

 much weaker than you have a right to demand of a 

 President. 



The aspects of agriculture from which it offers hopeful 



