perianth; pl, p2, p3, perianth segments; c, cavity left between the three pressed anthers; pol. pollen cylinder. × 40. Fig. 48. H. ovalis. Transverse section of central portion of perianth lobe showing internal rib. × 200. Fig. 49. H. ovalis. Transverse section of margin of perianth lobe. × 200. Fig. 50. H. ovalis. Transverse section of single anther cell; i, limiting layer. × 100. Fig. 51. H. oralis. Portion of pollen cylinder. Fig. 52. H. ovalis. Pollen cells united in a chain. men in glycerine. × 400. × 40. Fig. 53. Diagram of female flower from a shoot turned to the right; 7, subtending foliage leaf; v' v2, spathe leaves; p, perianth segments; sq. squamulæ intravaginales.' Fig. 54. H. ovalis. Female flower isolated, still enclosed in spathe v, through which the ovary with its beak is seen; the beak projects beyond the spathe leaves and bears the perianth segments p, and the styles st. × 4. Fig. 55. H. ovalis. Ovary with beak removed from spathe. The perianth segments seen at apex. × 10. Fig. 56. H. ovalis. Apex of beak showing perianth segments p, alternating with styles st, on which the bases of the grooves are Greatly magnified. seen. PLATE XII.-FIGS. 57-90. Figs. 57-61.-H. Ovalis. Fig. 57. Male flower on its pedicel, perianth segments closely imbricate on anthers. Magnified. Fig. 58. Male flower with perianth segments expanded. Anthers appressed. Magnified. Fig. 59. Male flower with anthers separated. Magnified. Fig. 60. Fruit enclosed by spathe. Magnified. Fig. 61. H. stipulacea. Spathe leaf. Magnified. Figs. 62-89.-H. Ovalis. Fig. 62. Transverse section of young fruit. Magnified. Fig. 63. Transverse section of pericarp. × 60. Fig. 64. Transverse section of beak of ovary. × 200. Fig. 65. Apex of beak with perianth segments p; st, styles, one is removed. Stigmatic papillæ are seen bounding the groove on the styles. Magnified. Fig. 66. Portion of tissue of style from margin of groove; t, papillæ. × 200. Fig. 67. Transverse section of style; t, stigmatic papillæ; g, × 200. groove. Fig. 68. Ovules on placenta. Magnified. Fig. 69. Ripe seed; r, raphe; ch. chalaza. x 25. Fig. 70. Vertical section of seed; ch. chalaza; pl. plumule; hyp. hypocotyledonary axis; cc, basal shooting portion of cotyledon; c c', coiled portion of cotyledon; fub. rudimentary fibrovascular bundle. × 25. Fig. 71. Embryo; hyp., hypocotyledonary axis; c, cotyledon. × 25. × 400. Fig. 72. Portion of testa. Surface view. Fig. 73. Vertical section of seed-coat; ol. outer cellular layer; cl. cuticular layers; end. endopleura; emb. cells of embryo. x 400. Figs. 74-83 Illustrate Development of Floral Axis and Flower. Fig. 74. Young lateral shoots with floral axis developing; n, scaleleaf, in axil of which shoot a rises; 112, foliage-leaves at base of shoot; bl. floral axis in axil of l1. x 200. Fig. 75. Further stage of floral axis. leaves. x 200. × 200. v2, beginning of spathe Fig. 77. Young male flower; vv, spathe leaves; p, perianth lobes; st, indications of stamens. × 80. Fig. 78. Same, more advanced; sq, 'squamulæ intravaginales.' × 60. Fig. 79. Same, in vertical section. Fig. 80. Same, farther advanced. × 60. × 25. Fig. 81. Young female flower; vv, spathe leaves; P, perianth lobes. × 70. Fig. 82. Female flower of an older stage; st. styles. × 60. Fig. 83. Section of female flower to show style jointed at the base. × 25. Fig 85. Nearly mature embryo; hyp. hypocotyledonary axis; c, cotyledon sheathing at the base around the plumule pl. Magnified. Fig. 86. Embryo having been treated with potash and the cotyledon removed; ax, apex of plumule; n, n, first leaves on plumule; through one is seen a tubercle marking apparently a branch of the plumule. Magnified. Fig. 87. Young seed with young embryo in situ seen through the seed-coat. Magnified. Fig. 88. Embryo removed; c, cotyledon as yet not much curved. Magnified. Fig. 89. Vertical section of young seed with embryo in situ, a little older than that of fig. 88; c, cotyledon now beginning to curve on itself; s, suspensory cells. Magnified. Fig. 90. Semi-diagrammatic projection of apex of primary axis, such as is presented in figs. 8 and 9. Only the three uppermost lateral shoots are here represented, but the lettering corresponds with that on those figures. XXVII. Note on the Effects of Soot on some Coniferæ.-BY DR T. A. G. BALFOUR, President. (Read July 1878.) I fear that the heading in the billet may have misled some as to the nature of the communication which I propose to make. It does not refer to the general action of soot on conifers, but has a much more limited range, which I shall best explain by mentioning the circumstances which led to the experiments being undertaken. At one of our most popular spring meetings, when the subject of the influence of soot on forest trees was incidentally brought before the Society by Mr Sadler, Dr Aitken made a statement to the effect that a German professor had proved that soot was quite innocuous to arboreal vegetation, by enveloping a tree in that substance without interfering with its vitality. So astounding was the announcement that I suggested that the soot could not have been applied to the under surface of their leaves, else the stomata must have been occluded, but I was informed that the experiment was so conducted that that portion of the leaf could not have escaped from being covered with soot. My special object then was to ascertain whether or not the free application of soot or other substances so as to cover the stomata, &c., was unattended with injurious results; and it is in this point of view alone that my experiments can be of any value. A second preliminary consideration to which I would allude is that the experiments are liable to objection in consequence of my having been unable to give the time necessary for close and continuous observation of the results, and still more from the fact that the experiments were not. crucial ones, seeing that different kinds of plants were made the subjects of them. But, as I feared from the first that the issue would be disastrous, I felt reluctant to ask for any plants for experimental purposes other than those which. were kindly supplied to me; but still even this circumstance, though prejudicial in one respect, may have its advantages in another. To a third preliminary point I should like to direct your attention, viz., to this, that questions such as those which were brought before us by Mr Sadler can only be satisfactorily answered by experiments on a large scale, and where all the circumstances in connection with it are in every respect similar to those in the case in dispute,—thus, for instance, the kind of coal employed, the amount of iron pyrites in the clay or blackband ironstone being calcined, the distance from the plantation at which the calcination is effected, the general direction of the winds in the district, and the frequency and amount of rain which falls, must all be taken into account, and would require to be imitated as exactly as possible before reliable experiments could be adduced. These considerations, taken in connection with the subject of smoke, to which I shall shortly refer, are sufficient to show that my experiments can have only a most distant and indirect bearing on the important general question which was before us at our previous meeting. The substances used in my experiments were only three-soot, lamp-black, and whitening. Sand was used in one instance, but it proved so heavy that it weighed down the plant inconveniently, and was therefore discarded. Now soot, as every one knows, varies in its composition according to the nature of the coal from which it is derived, and as it is the result of imperfect combustion of organic matters, even the height and nature of the chimney must exert an influence upon its composition. The better quality of the Bristol soot over that of Gloucester is said to be owing to the greater length of the chimneys. The analysis of Braconnot seems clearly to indicate from the presence of acetates that the combustion had been unusually deficient in the supply of oxygen, which would otherwise have changed them into carbonates. Analysis of Soot by M. Braconnot. Ulmic acid (a substance resembling that portion of the vegetable A reddish brown soluble substance containing Carbonate of lime with a trace of magnesia, pro bably partly derived from sides of chimney, Acetate of lime, 302.0 200.0 5.0 146.6 56.5 But yet there is an average composition, which, from the analysis of Dr Völcker, may be stated to be as in the following tables :— Analysis of House-Coal Soot by Dr Völcker. • From ảo Boλn, soot, is a substance analogous to hamus or ulmic acid, but contains nitrogen. |