February 9, 1922] 



NATURES 



189 



■*HE Edinburgh meeting will be long remem- 



bered among botanists as that at which a 



nsideration of the oldest land flora, namely, that of 



e Rhynie Chert beds, took a prominent place. This 



bject bulked largely in the president's address; it 



rmed the basis of a series of papers presented to a 



joint meeting of the Sections of Botany and Geology, 



and it was fully illustrated by a marvellous series of 



microscope preparations demonstrated by Dr. Lang 



and Dr. Kidston in the laboratory of the Royal 



Gardens. 



The Rhynie Chert beds of Devonian age contain 

 identifiable remains of algee, fungi, and bacteria, but 

 the chief interest attaches to the forms which, though 

 classified as vascular cryptogams, present in many, 

 respects little more differentiation than a seaweed, 

 and, indeed, show many resemblances to some of the 

 higher seaweeds of the present day. They are leafless 

 and rootless forms bearing sporangia scarcely differen- 

 tiated from the vegetative portion of the axis. Never- 

 theless, they are undoubted land plants, as shown by 

 "the presence of water-conducting tissue and stomata 

 and by manifestly air-borne spores." The function 

 of roots was apparently performed either by root- 

 hairs or by special branches of the rhizome. The 

 spores were usually borne on terminal sporangia 

 which were evidently fertile branch endings. 



Dr. Lang described the plant remains found in these 

 beds, and more particularly those of the vascular forms 

 constituting the family of the Rhyniaceas, viz. a fila- 

 mentous alga probably allied to' the modern blue- 

 greens ; another form which appears to be connected 

 with the Characeas; and a fragment of the supposed 

 seaweed Hematophyton, showing for the first 

 time its external characteristics, together with 

 several members of the fungi. The Rhyniaceae include 

 Rhynia major and R. Gwynne Vaughanii, Hornea 

 Lignieri, and Asteromyelon Mackei, the latter with its 

 small investing leaves being the most complex. The 

 vascular tissue is of a very simple order, the water- 

 conducting elements being 'spirally thickened and the 

 phloem elements large and thin-walled with oblique 

 ends. The latter tissue is continuous with a central 

 column in the sporangial heads, recalling the 

 columella of the mosses. 



The vertical distribution of the various forms in the 

 peaty beds of the chert indicates that petrifaction 

 occurred in the lower parts of the bed while plants 

 were still growing on the higher parts. Probably the 

 irritating action of vapours from a volcanic fumarole 

 in the neighbourhood caused the necroses and swell- 

 ings observed on the plants. 



Dr. Home stated that recent work pointed to the 

 Continental origin of the deposit and indicated that 

 the Rhynie plants actually grew where thev were pre- 

 served. 



Dr. Kidston concluded that if Asteroxylon were 

 flattened out and preserved as an impression it would 

 resemble very closely the middle Devonian species 

 called Thyrsophyton Millcri, and he believed that the 

 fact afforded some indication of the Middle Old Red 

 Sandstone age of the Rhynie bed. 



Several of the later speakers directed their remarks 

 more^ to the theoretical importance of these dis- 

 coveries and their relation to modern theories of 

 evolution. This had been dwelt upon at some length 

 by Dr. Scott, who emphasised the present-dav lack 

 of unanimity with regard to the nature and 'extent 

 of variation as the material upon which evolution 

 NO. 2728, VOL. 109] 



Botany at the British Association. 



works. Dr. Lotsy pointed out the dilemma summed 

 up in the phrases "like breeds like" and "like may 

 breed unlike." He thought that the great phyla were 

 widely separated, and had possibly separate origins, 

 and while for classes of plants, as generally con- 

 sidered by the palaeobotanist, the first phrase em- 

 phasised the truth, when the smaller units or species 

 were considered it was clear that frequently "like 

 breeds unlike." 



(&) Forestry and its Problems. 



A whole day was devoted to forestry, the Botany 

 and Zoology Sections holding joint session 

 during the part of the programme concerned with 

 insect problems. Mr. J. Sutherland, Assistant Com- 

 missioner for Forestry in Scotland, gave a very com- 

 plete account of the past and present position of 

 forestry in Great Britain, and enumerated in an ex- 

 haustive manner the advantages of a consistent State 

 policy of extended afforestation. The new forestry 

 poHcy now provides that the 3,000,000 acres of 1914 

 shall be increased during the present century by 

 1,750,000 acres of coniferous trees, and that two-thirds 

 of the programme shall be completed during the next 

 forty years. This programme cannot, however, be put 

 into actual effect without the co-operation of land- 

 owners and State. A large proportion of money ex- 

 pended in forestry becomes available as wages, and 

 consequently it provides a great stabilising influence 

 in keeping workers in rural areas. He quoted the 

 increase of population from 69,000 to 289,000 which 

 has taken place in the Landes Department of France 

 as a result of afforestation. He further indicated the 

 immense importance of forests in time of war. 

 _ Prof. Stebbing traced the history of Indian forestry 

 since 1850, when a committee of the British Associa- 

 tion was set up at the instigation of Dr. Cleghorn 

 "to consider the probable effects from an economic 

 and physical point of view of the destruction of 

 tropical forests in India." The result of the efficient 

 management of the Indian Forest Department shortly 

 afterwards set up has been a plentiful supply of 

 forest products and a considerable annual revenue. 



Dr. Borthwick and Prof. Henry both urged the 

 importance of selecting the varieties most suitable to 

 the climatic conditions found in the country, and 

 expressed the opinion that the State might reasonably 

 undertake the protection of forests from devastating 

 fires. 



(c) Quantitative Analysis of Plant Growth. 



The discussion on "The Quantitative Analysis of 

 Plant Growth " was introduced by Dr. Lawrence 

 Balls, who illustrated his points largely by reference 

 to the cotton plant. The problem of plant growth is 

 a physico-chemical one, and therefore must be ex- 

 plored by quantitative methods and checked by statis- 

 tical treatrnent. Dr. Balls hinted at the possibility 

 of elucidating geometrical constructions in the ceil 

 parallel to those established by Dr. Church for ex- 

 ternal form. This would furnish developments akin 

 to those which the study of atomic structure has 

 brought to the physicists. The recent advance in 

 physiological thought as well as in actual technique 

 gives us reason to expect rapid increase of knowledge 

 even in so intricate a problem as that of growth. 



Contributions to this discussion were made by 

 Messrs. Briggs, Kidd, and West on "The Quantita- 

 tive Study of the Growth of Helianthus annuus,^^ and 

 by Prof. Priestley and Miss Evershed on " A Quantita- 

 tive Studv of the Growth of Roots." 



