June. 1913. 



KNOWLEDGE. 



219 



FAIRY RING FUNGI.— Miss Bayliss (Jourtl. Econ. 

 Biol., Vol. VI) has found that the well-known " fairy ring " 

 fungi Marasmius oreades and Clitocybc gigantea are not 

 saprophytes, but are parasitic on the roots of grasses, which 

 they kill by the secretion of some toxic substance. The same 

 or some other secretion is toxic to the fungi themselves, 

 making them unable to grow in the same soil for three years 

 in succession, and hence producing the well-known develop- 

 ment of yearly widening rings. As compared with the 

 infected grass, that which lies just outside as well as that 

 inside the ring is stimulated into better growth by the greater 

 abundance of nitrogenous food which is made available by 

 the action of the mycelium of the fungi in secreting protein- 

 digesting ferments (proteolytic enzymes). The yearly increase 

 in the radius of the rings was measured — in the case of 

 Marasmius oreades it was found to be from six to fourteen 

 inches. 



CAUSE OF LEAF-FALL. — From experiments made with 

 detached twigs of various deciduous trees placed in water in 

 a saturated atmosphere Varga (Oesterr. bot. Zeitschr., 

 Band 61) has sought to establish a relationship between this 

 familiar phenomenon and the processes of transpiration and 

 photosynthesis influenced by various conditions of light and 

 temperature. He concludes from the results of his experi- 

 ments that (1) any decided checking of photosynthesis, either 

 from light conditions or from a deficiency of carbon dioxide, 

 brings about leaf-fall ; (2) any lowering of transpiration also 

 induces defoliation, but less rapidly than diminished photosyn- 

 thesis; (3) variation in the intensity and quality of the light 

 has no direct specific action upon leaf-fall ; (4) lower tempera- 

 tures are effective in producing leaf-fall through decreased 

 photosynthesis and transpiration only within limits which 

 allow the activities involved in the development of the 

 absciss layer — below these limits the leaves die, but cling 

 rather persistently to the twigs. 



CHEMISTRY. 



By C. Ainsworth Mitchell, B.A. (Oxon.), F.I.C. 



INSTITUTE OF METALS.— At the annual general meet- 

 ing of the Institute, on March 11th and 12th, 1913, the Report 

 of the Council was presented by the President. From this it 

 appears that there has been a steady increase in the number 

 of members, which has risen from three hundred and fifty-five 

 in 1908, to six hundred and fourteen in 1912. 



Six papers were also read on this occasion by Fellows of the 

 Institute. These included a study of the "Corrosion of 

 Aluminium," by Dr. G. S. Bailey, in which it is shown that 

 the results obtained by acting upon the metal with acids or 

 alkalies afforded no definite indication of its behaviour in the 

 presence of water or solutions of salts. In the paper read by 

 Mr. Siemens upon " Metal Filament Lamps," an account is 

 given of the evolution of the processes of preparing the wire for 

 these lamps, descriptions of many of which have been given 

 in these columns. The general conclusion reached, is that it 

 is doubtful whether it will be possible to construct a much 

 more economical glow-lamp than the tungsten lamp, and that 

 further progress must be sought in the directions of the 

 improvement and cheapening of the electric supply. The 

 remaining papers by Mr. Gulliver, Messrs. H. & J. Primrose, 

 Mr. Hudson, and Mr. A. Philip are more purely technical in 

 character. 



NEW GERMAN INK REGULATIONS.— An account is 

 given by Dr. Hinrichsen in the Chemiker Zeitung (1913, 

 XXXVII, 265) of the Prussian regulations for the official tests 

 of writing ink, which came into force last year. In these 

 regulations inks are classified into " documentary " and 

 " ordinary writing inks," and the methods for their analysis 

 and examination are outlined. For example, a " docu- 

 mentary " ink must contain at least twenty-seven grammes of 

 anhydrous gallotannic and gallic acids, with at least four 

 grammes of iron, per litre, and the ratio of tannin to iron must 

 lie within the limits of 4-5:1 and 6-75:1. Ordinary iron- 



gall writing inks may contain less tannin, but must still have 

 the same ratios of tannin and iron. 



Both kinds of ink must show no alteration in the ink-pot for 

 at least fourteen days, must flow readily from the pen, and 

 must give writing which after being exposed for eight days to 

 the air, is deep black, and can be washed with water and with 

 dilute alcohol. 



In testing the permanency-of the writing, pieces of standard 

 paper are stretched in a frame inclined at an angle of 45°, and 

 a definite quantity of the ink is made to flow over this paper 

 from a pipette, which is placed in a rest on the frame, so that 

 it is always at the same angle. Simultaneously, parallel ink 

 bands are made upon the paper with a standard ink of known 

 composition, prepared in a definite manner. 



The paper, with the colour bands of the two inks upon it, is 

 exposed for eight days in diffused daylight, and is then cut 

 horizontally into three strips. One of these is immersed in 

 water, the second in fifty per cent, alcohol, and the third in 

 eighty-five per cent, alcohol. In none of the strips should 

 there be any perceptible bleaching of the ink. 



HARDNESS OF RAINWATER.— Rainwater is commonly 

 regarded as one of the purest forms of natural water, but this 

 is not always the case with the rain that falls in large towns 

 and especially in industrial centres. For example, some years 

 ago it was found that the rainwater in Paris was decidedly 

 hard, and the cause of this was traced to the dust from 

 macadamised roads, the salts in which had been taken up by 

 the rain during its passage through the air. 



Another remarkable instance of hard rainwater has recently 

 been investigated by Dr. S. Wolff (/. Soc. Chem. Ind., 1913, 

 XXXII, 345). The water used in some large works outside 

 Manchester has frequently given trouble on account of its 

 hardness, though consisting largely of rainwater collected from 

 the roofs of the buildings. All the samples of the rainwater 

 examined prior to their entering the reservoir were found to 

 be decidedly hard and to give an alkaline reaction. In some 

 of them the proportion of dissolved calcium salts was so great 

 that a scum could be formed by blowing into the water. 



A specimen of rainwater collected directly from the roof 

 contained one hundred and seventy parts of total solids per 

 one hundred thousand, and had a total hardness of 87-2 and 

 temporary hardness of 15 '75. 



In the discussion upon this paper it was mentioned by Mr. 

 W. H. Coleman that much of the coal used in the neighbour- 

 hood of the works came from the Bradford Colliery, and that 

 this coal was rich in crystallised carbonate, and it was 

 suggested that the smoke from this coal might convey calcium 

 compounds into the air. Apart from this, a considerable 

 quantity of flue dust must be blown up the chimneys into the 

 air, and a considerable quantity of this must settle upon the 

 roofs ; whence some of its soluble constituents would be 

 dissolved by the falling rain. 



GEOLOGY. 



By G. W. Tyrrell, A.R.C.Sc, F.G.S. 



OLD RED SANDSTONE AT SOUTHALL.— The in- 

 teresting discovery of Palaeozoic rocks made by E. Proctor 

 in a boring at Southall is described in the current volume of 

 The Quarterly Journal of the Geological Society. The plat- 

 form of old rocks was struck at a depth of one thousand one 

 hundred and thirty feet, and continued to one thousand two 

 hundred and sixty-one feet, the total depth of the boring. 

 After two hundred and sixty-two feet of gault, the boring 

 entered red and green mottled clays and sandstones, with 

 occasional bands of fine conglomerate. On breaking up the 

 cores remains of fossil fish were found in a marked type of 

 rock occurring in thin bands and consisting almost entirely 

 of organic remains associated with rounded and subangular 

 grains of quartz. The fossils, as determined by Dr. Smith 

 Woodward, consist of scales and teeth of Holoptychius and 

 plates of Bothriolepis, both of which are characteristic of 

 the Upper Devonian or Old Red Sandstone. This discovery 

 creates a probability that other but unfossiliferous Red Rocks 

 found in other borings in the London Basin are of the same age. 



