October i8, 1900] 



NA TURE 



61 



General. 



Prof. Bower, F.R.S , gave an account, illustrated by several 

 excellent photographs, of sand-binding plant as seen in the dunes 

 on the Scotch coast in the neighbourhood of North Berwick. 



British sylviculture, by Samuel Margerison. In this commu- 

 nication atteniion was called to the large importation of foreign 

 timber, and the urgent need of Government aid in the produc- 

 tion of British timber. The author spoke of the existence of 

 much land in this country at present unproductive, or only 

 slightly productive, which is suitable for giving a native supply 

 of timber. He compared the results of Continental and British 

 sylviculture, and pointed out that in Britain the natural condi- 

 tions are not less favourable, but the management is generally 

 inferior. The author urged the importance of encouraging 

 forestry schools which should afford opportunities for detailed 

 research and teaching, with equipment, scientific and practical, 

 worthy of the subject. 



The great smoke-cloud of the North of England and its in- 

 fluence on plants, by Albert Wilson. The author spoke of the 

 extent of the great smoke-producing district of the North of 

 England and the miserable condition of the vegetation in some 

 parts of the area. Among the various points dealt with in the 

 paper, the following may be mentioned, the long distance 

 reached by the smoke of large towns ; the discoloration of rain- 

 water ("black rain ") ; the effect of smoke on mosses and 

 hepatics as compared with that on higher plants ; the threat- 

 ened extinction of Ulota and Orthotricha ; the influence of 

 smoke on sunshine and air-temperalure in calm summer 

 weather and in anti-cyclonic weather during autumn or winter. 



Embryonic tissues, by Prof. Marshall Ward, F.R.S. The 

 author urged the advisability of improving the current termin- 

 ology with regard to the nature and growth of the tissues termed 

 embryonic. Sachs termed all the tissues of the growing-points, 

 cambium, pericycle, &c., embryonic tissues. Prof. Ward would 

 restrict the term embryonic tissue to that of the embryo alone 

 before the desmogen strands are developed, the other tissues 

 being designated derived ox secondary tissues. The tissues of the 

 growing-points are derived from embryonic tissue, and differ 

 from it in that, instead of being capable of developing all or any 

 part of the plant, they are more or less restricted to the power 

 of developing shoots, leaves, &c., or only roots. The pro- 

 posed classification would apply equally to the lower organisms ; 

 some of the Algas and Schizomycctes appear to be always in the 

 embryonic stage. Prof. Ward also urged the desirability of 

 distinguishing between iht as si mtlatory gjov/ih of true embryonic 

 tissues and the vacuolar p-owth of the derived tissues. 



Physiology. 



Dr. F. F. Blackman and Miss Matthaei communicated the 

 results of their recent work on the effect of the closure of stomata 

 on assimilation ; Dr. Blackman also gave an account of his 

 investigations on the so-called optimum strength of COg for 

 assimilation. 



Formation of starch from glycollic aldehyde by green 

 plants, by Henry Jackson. Glycollic aldehyde has lately been 

 isolated in a crystalline state, and more recently it has been 

 shown by the author that this substance, under the influence of 

 dilute alkalis, very quickly condenses to two synthetic hexoses. 

 Leaves of Tropaeoluin and clover, which had been depleted of 

 their starch by growing in the dark, were floated in a three per 

 cent, aqueous solution of diose, control experiments being made 

 with cane-sugar, glycerine and distilled water, the whole series 

 being kept in the dark for six days. They were then tested by 

 Sach's method ; those floating in pure water were quite starch- 

 less, those in glycerine almost so, but those growing in diose 

 had accumulated starch in the tissues, though not to the same 

 extent as those placed in cane-sugar. 



On the effect of salts on the COj assimilation of Ulva 

 latissitna, L., by E. A. Newell Arber. It was found that an 

 inhibition of the power of COj assimilation could be caused by 

 the presence or absence of certain salts in the medium. Ulva 

 was obtained free from starch and exposed to light in various 

 media. In distilled water only a very small amount of starch 

 was formed, while in tap-water containing traces of nutrient 

 salts the inhibition was only partial. The presence of NaCl in 

 the medium was found to be essential in order to obtain the 

 maximum of COj assimilation. A total or almost total absence 

 of NaCl caused a very marked inhibition, and no other salt could 

 be found to replace NaCl in regard to CO.2 assimilation. The 

 absence from sea-water of any one of the following salts, 



NO. It) 1 6 VOL. 62I 



MgCLj. MgSOj, CaSO^, or KCI, did not inhibit the assimila- 

 tion. The presence of a nitrate in appreciable quantity in the 

 medium caused an inhibition. 



The sea-weed Uiva latissima and its relation to the pollution 

 of sea-water by sewage, by Prof. Letts and J. Hawthorn. For 

 a number of years past a very serious nuisance has arisen from 

 the sloblands of the upper reaches of Belfast Lough during the 

 summer months, "the stench at low-tide being quite overpowering, 

 and the air heavily charged with sulphuretted hydrogen. 



The nuisance is caused by deposits of the green sea-weed, 

 Ulva latissima, which in the two localities mentioned grows in 

 abundance, and during high winds or gales is washed ashore. 

 In Belfast Lough the quantity thus deposited is enormous. 

 Once deposited, these layers of sea-weed often remain more or 

 less stationary for months in the shallow bays or pools of the 

 neighbourhood, and in warm weather rapid putrefaction occurs, 

 and a perfectly intolerable stench arises, which is perceptible 

 over a wide area and seriously affects, not only the comfort of 

 the inhabitants of the district, but also the value of their property. 



The evidence which the authors have collected tends to the 

 conclusion that the occurrence of Ulva latissima in quantity in a 

 given locality is an indication of sewage contamination, and 

 there can be no doubt as to the power which the weed possesses 

 of absorbing nitrogen compounds from polluted sea-water. 

 While thus acting as scavenger it may itself give rise to a very 

 extensive nuisance. 



Further investigations on the intumescences of Hibiscus 

 vitifolius, L., by Elizabeth Dab. In a previous paper (/Voc. 

 Phil. Soc. Camb. vol. x. 1900, p. 192) the author gave the 

 results of some experiments, which pointed to the conclusion 

 that the conditions determining the formation of the outgrowths 

 were moisture, warmth and light. More recent work has given 

 the following results: (i) In a moist atmosphere, bright sun- 

 light and a high temperature, large numbers of intumescences 

 were formed m two or three days ; (2) outgrowths were pro- 

 duced under red, yellow and white- washed glass, but not under 

 blue or green glass ; (3) the distribution of outgrowths is 

 dependent upon that of the stomata ; (4) the checking of 

 transpiration in a damp atmosphere is one cause of the develop- 

 ment of the outgrowths, but this in itself is insufficient. There 

 is further evidence that an altered course of metabolism is also 

 involved. 



Anatomy, Pal^^jobotany, &c. 



On a fourth type of transition from stem to root-structure 

 occurring in certain monocotyledonous seedlings, by Ethel 

 Sargant. Van Tieghem dercribed three types of transition from 

 a stem to a root-structure ( 7>aiVi/ fl?'^ Botanique, 1891, p. 782). 

 Miss Sargant found a fourth type in certain monocotyledonous 

 seedlings. The best example is Anemarrhena asphodeloities, 

 but there are very clear traces of the same structure in some 

 allied genera. In Anemarrhena asphodeloidcs there are two 

 bundles in the cotyledon which pass downwards through the 

 hypocotyl into the primary root. During the transition each 

 phloem group divides into two. Each xylem group branches in 

 three directions. It sends a group of protoxylem elements to 

 divide its own two phloem groups from each other. Two 

 lateral protoxylem groups are also formed from the xylem of 

 each bundle in the space dividing the bundles from each other. 

 The four lateral protoxylem groups thus formed are reduced to 

 two by the fusion of adjacent groups in pairs. In the end, 

 there are four phloem groups and four protoxylem groups in the 

 root-stele. 



On the presence of seed like organs in certain Palaeozoic 

 lycopods, by Dr. D. H. Scott, F.R.S. Specimens discovered by 

 Messrs. Wild and Lomax in the Lower Coal-measures of Lan- 

 cashire prove that the seed-like bodies described by Williamson 

 under the name of Cardiocarpon anomahim were borne on 

 strobili, agreeing with Lepidostrobus. Each megasporangium, 

 which was seated on the upper surface of the sporophyll, became 

 enclosed, when mature, in an integument springing from the 

 tissue of the sporophyll-pedicel. The integument closed in over 

 the top of the sporangium, leaving only a narrow crevice or 

 micropyle, which differed in its elongated, slit-like form from the 

 more or less tubular micropyle of an ordinary seed. Within the 

 megasporangium four megaspores were produced, one of which 

 occupied almost the whole of the sporangial cavity, while the 

 other three remained small, and were evidently abortive. The 

 integumented megasporangium, containing the single functional 

 megaspore or embryo-sac, became detached, together with the 

 remains of its sporophyll, from the cone. It appears to have 



