3o3 



SCIENTIFIC NEWS. 



[Mar. 30, 1888. 



engine, working with low-pressure steam, it worked 

 with remarkable economy of fuel. The next step in 

 advance was the compound differential engine invented 

 by Mr. Henry Davey, which worked as economically as 

 the Cornish engine, but without the excessive strains on 

 the pitwork which had hitherto been unavoidable, and 

 which automatically pulled up in case of a sudden loss of 

 load. Numerous attempts had from time to time been 

 made to convey power from a steam engine on the sur- 

 face to pumps placed in the mine at a distance from the 

 shaft, compressed air, or water under pressure, being 

 the agents mo=t frequently adopted. As the very low 

 rate of efficiency olstained from compressed air pro- 

 hibited its use for pumping purposes, except in very 

 special cases, hydraulic power had been largely em- 

 ployed. This w.^s of special value in mines liable to 

 flooding, as the hydraulics worked equally well, though 

 buried in water. Mr. Meysey-Thompson exhibited a 

 model and drawings of the arrangements recently 

 patented by Mr. Davey, which enables direct-acting 

 steam pumps to be worked with a high degree of ex- 

 pansion, and consequent economy of fuel, without the 

 necessity of using fl5'-wheels and similar devices. 



ROYAL HORTICULTURAL SOCIETY. 

 At the meeting of the Scientific Cornmittee on March 13th, 

 a new species of strophanthus (S. tnadagascariensis) 

 was exhibited. The genus is African, of the order 

 Apocynaceas, or ''Dogbanes," the name being derived 

 from the cord-like appendages to the corolla. It is re- 

 markable for the structure and poisonous properties of 

 the seed. The latter somewhat resembles that of the 

 Dandelion, but is larger, and has the silky hairs distri- 

 buted down the greater part of the shaft. The natives 

 crush the seeds, from which a red oily mass is obtained, 

 with which they smear their arrow points. Several 

 varieties or species are known, but more material is re- 

 quired for an accurate discrimination of them. As a 

 drug, the active principle Strophanthin, is found in all 

 parts of the pod as well as the seed, and is a very 

 powerful poison, one-fiftieth of a grain killing a large 

 dog. It seems likely to prove to be a valuable remedy 

 for deranged action of the heart. 



Mr. T. Christ^' sent a specimen of Manaca or Mcrciirio 

 Vegetal root, the medicinal root of Franciscca uniflora, 

 the bark of which contains the active principle Francis- 

 ceine. The root is of a woody nature, tapering, of a 

 light-brown colour externally, of a cinnamon-brown 

 within. From Dr. J. Hutchinson's experience it would 

 appear to be a valuable new remedy for rheumatism, 

 especially of a certain type. 



Mr. Henslow explained the cause of so many Pears 

 being unsymmetrical about their axis. This was only 

 the case when the stalk was not vertical and the want of 

 symmetry increased with its obliquity. He attributed 

 the growth to the effort of the Pear to meet the strain 

 imposed upon the stalk as the fruit increased in weight. 

 The two forces to which it is subjected are gravitation, 

 or the weight acting in a vertical direction, and the 

 tension along the stalk. The resultant of these two 

 forces tended to wrench the fruit from the latter at its 

 point of insertion at the base of the Pear. To meet this 

 strain the fruit thickened in the opposite direction, so that 

 the " hump " is always at the base and on the outer or 

 opposite side of the fruit. The effect often extends over 

 the whole of the outermost half of the Pear, so that a 



vertical plane at right angles to the one in which the 

 stalk lies cuts the Pear into two very unequal portions. 

 When the stalk hangs vertically, as is more usually the 

 the case in apples and oranges, there is little or no 

 obliquity, so that the fruit grows symmetrically round 

 all points of its axis, the radii of the circular transverse 

 sections being all equal. 



LIVERPOOL GEOLOGICAL SOCIETY. 

 At the meeting on March 13th, Mr. T. Mellard Reade 

 described the large greenstone boulder which has just 

 been placed in the quadrangle of Owens College, Man- 

 chester. It was found about 30 ft. below the surface of 

 Oxford-road, Manchester, during the formation of a 

 drain. It weighed between twenty and thirty tons, and . 

 was about to be blasted when the Owens College authori- 

 ties heard of it, and had it brought out as a geological speci- 

 men. The large boulder in Sefton Park, which was 

 found at St. Ann's Church, Edgehill, only weighs about 

 seven tons, so that the Manchester specimen is a giant 

 compared to it. This boulder was found in the boulder 

 clay, and therefore had probably been deposited by a 

 glacier which brought it from the Lake District, when 

 the climate of this country was very different from what 

 it is now. 



♦-J»t^<^5<^ 



THE FORMATION AND FUNCTIONS OF 

 STOMATES.— I. 



IF the skin of the under side of the leaf of a land plant 

 be stripped off and exam.ined by transmitted light 

 under the microscope with a power of about 300 dia- 

 meters, a plate of flat, whitish, transparent cells (very 

 small bladder-like structures) v.'ill then be displayed to 

 the view. In this plate of tissue there will be observed, 

 situated at more or less regular intervals, certain little 

 structures which differ from the surrounding cells by 

 their smaller size, their generally roundish or elliptical 

 shape, and by their being divided in half by a line 

 which swells in the middle into a clear, narrow space. 

 They differ still further by possessing minute grains of 

 chlorophyll — the substance which gives the green colour 

 to trie stems and leaves of plants — of which the other 

 cells of the epidermis, or the skin of plants is usually 

 destitute. The small clear spaces in the middle of these 

 structures are openings, and, as will be afterwards ex- 

 plained, it is by means of such openings, known as Sto- 

 mates or Stomata, that very important work is done in 

 the plant, whilst the two parts of the divided oval cell 

 enclosing the opening forms the two guard-cells which 

 by their expansion and collapse regulate the opening and 

 closing of the stomate. A rough resemblance to the 

 arrangement thus produced, would be made by cutting 

 an oval-shaped piece of paper, and then drawing a line 

 over its longer diameter to represent the cell-wall or 

 partition, and finally by cutting out an oval space in 

 the centre to resemble the stomate or orifice ; the two 

 portions of the black line then left between the ends of 

 the opening and the margin of the paper would repre- 

 sent the two portions of cell-wall by which the guard- 

 cells are attached. The surface of the whole stomal 

 apparatus, however, is not flat like the paper but roun- 

 dish, or otherwise, according to the species of the plants 

 bearing them. These stomates arise late in the deve- 

 lopment of the epidermis, sometimes n&t until after 

 the expansion of the bud. Their arrangement on the 

 epidermis differs greatly and is dependent upon the 



