366 



KNOWLEDGE. 



September, IQIO. 



is possible, however, that this may be due to the formation of 

 gallic acid by fermentation from the cUagitaniiic acid and 

 the results of some experiments made by the writer support 

 this view. 



THE INK-PL.\NT.— By a slip, the illustration of Coriana 

 myrtifolia in the last issue, was described as the " ink-plant," 

 whereas the name should have been restricted to the other 

 member of the family. C. thyinifoUa. 



ACTION OF SULPHURETTED HYDROGEN ON 

 WHITE LEAD. — It is a matter of conunon laiowledge that 

 white lead paints exposed to the air of towns darUen, owing to 

 the action of the sulphuretted hydrogen, derived mainly from 

 the smoke from coal. Experiments recently made by Mr. J. 

 Sacher [Clieni. Zeit., 1910, .14. 647) show that only the lead 

 atoms attached to the hydroxy! group in the white lead re-act 

 with the gas to form lead sulphide. Thus, if the absence of 

 lead hydroxide or of basic lead carbonate from white lead 

 could be ensured, the pigment should not become discoloured. 

 In an experiment in which a current of sulphuretted hydrogen 

 was passed through absolute alcohol in which white lead was 

 suspended, only two per cent, of sulphur was absorbed, the 

 product ha\ing a composition agreeing with the formula 

 4PbCOa, PbS, Pb(OH)2. On the other hand, when the white 

 lead was suspended in hot water and the gas passed through 

 the liquid, the product contained five per cent, of sulphur, 

 owing to the formation of basic lead carbonate, PbCOa, 

 Pb(OH)-2, by the action of the water on the normal carbonate, 

 and the interaction of the resulting (OH) group with the 

 sulphuretted hydrogen. It was found that the brown lead 

 sulphide formed in these experiments was not bleached after 

 being exposed to sunlight for three years in a sealed glass tube. 



ECONOMIC BIOLOGY. 



By W.Sii.TER E. CoLLiNGE, M.Sc. F.L.S., F.E.S. 



WEEDS. — The subject of weeds and their control is one 

 that must ere long receive more than passing attention. The 

 manner in which Urban and District Councils, Railwav 

 Companies, and Land Owners permit weeds to grow and 

 flourish upon their land is one that calls for very drastic steps, 

 for the losses to farmers and horticulturalists through the 

 neglect of such land must be enormous. Unfortunately, in 

 this country, we have no law which makes it incumbent upon 

 the people mentioned above to destroy the weeds, which 

 flourish upon their land and spread their seeds on to neigh- 

 bouring cultivated land. Hitherto the farmer has looked on 

 in silence, but there are signs that he is beginning to realize 

 that a plague of weeds is as bad as or worse than a disease 

 amongst his live-stock, and very soon he will demand that 

 those who have the control of land adjoining his shall at 

 least keep it free from plants which rob him of part of his 

 crop, that encourage injinuous insects, fungi, etc. 



DISADVANTAGES OF WEEDS.— In a recent paper. 

 Dr. W. J. Real iMicli. Agric. Exp. Station. Bull. 260) points 

 out in a very pertinent manner the disadvantages of weeds. 

 That they r >b cultivated plants of nutriment and injure crops 

 by crowding md shading is generally appreciated, but they 

 also retard the work of harvesting by increasing the draft, and 

 extra wear of machinery. The increased labour of threshing 

 and the cleaning of seed are also points to be considered. 

 Very few weeds are of any value as food for domestic animals, 

 whilst many are injurious, especially those having barbed awns 

 and those that contain strong acid or other objectionable 

 contents which injure the (juality of dairy products and the 

 taste of meat. Some, of course, are distinctly poisonous. 



Amongst the few advantages, ho mentions that they induce 

 more frequent and more thorough cultivation, which benefits 

 crops, and in occupying the soil after a crop has been removed 

 they prevent the loss of fertility by shading the ground, whilst 

 if ploughed under they add some humus and fertility to the soil. 



THRIPS. — The increased interest that has been taken in 

 economic biology of recent years has indirectly been the means 

 of directing attention to some of the minute and less known 

 animals and plants, such, for instance, as the Protozoa, Ticks, 

 Springtails and Thrips. The latter insects we are pleased to 

 note are recei\ing very thorough and careful treatment at the 

 hands of Mr. R. S. Bagnall. a number of whose recent writings 

 are before us. As is frequently the case with neglected orders 

 or families, the points of interest zoologically and economically 

 are almost endless, and the careful study Mr. Bagnall is 

 making of these insects is bringing to light many of far-reaching 

 importance. 



ANAPLASMOSIS OF CATTLE.— The disease of cattle 

 known as anaplasmosis is due to the presence of a somewhat 

 remarkable protozoon I Aiiaplasnia marginalc I. which, so far, 

 has no simile in protozoology, so Dr. Theiler informs us in a 

 most valuable article in the last issue of the Transvaal 

 Agricultural Journal. This protozoon consists of only a 

 chromatic substance — a nucleus, without the surrounding 

 protoplasmic body. Occasionally around the parasite there 

 can be seen a paler zone, the globule apparently not staining 

 here as well as the rest. Reproduction takes place by fission. 

 They multiply rapidly and in susceptible animals invade and 

 destroy a large percentage of the red blood corpuscles. .\s a 

 rule the parasites are situated on the periphery of the 

 corpuscles, but they are also found in the centre of the 

 corpuscles. The disease is found all over Africa and has also 

 been described from North .America and the Transcaucasus. 

 No experiments have yet been made with the modern drug 

 " Trypanblaii." which seems to have a beneficial influence in 

 allied diseases. 



GEOLOGY. 



By G. W. TvRRELi.. A.R.C.S., F.G.S. 



CARBONIFEROUS GLACIAL BOULDER - BED IN 

 WEST AUSTRALIA.— An addition to the already long list 

 of Palaeozoic boulder-beds has been made in West Australia 

 by the Government Geologist, A. Gibb Maitland. It occurs 

 among the Basal Beds of the Carboniferous in the Gascoyne 

 River Valley. The best sections, however, are exposed in the 

 .\rthur River, where the boulder-bed, whose thickness is not 



mentioned, rests on sandv and flag 



limestones, and is 



overlain by a limestone conglomerate. The matrix is a very 

 calcareous clay, which is crowded with beautifully striated 

 boulders. The boulder-bed is seldom seen in place, although 

 its presence is always indicated by the heterogeneous collection 

 of boulders resulting from its weathering. It forms a valuable 

 stratigraphical horizon, which may be followed across country 

 for scores of miles. The occurrence is described in the 

 recently issued Bulletin, No. 3J. of the Geological Survey of 

 West Australia. 



NEPHELINE SYENITES OF EASTERN ONTARIO.— 

 The enormous areas of nepheliue syenite in Ontario, said to be 

 the largest development of this rock in the world, have been 

 recently described by Messrs. .•\dams and Barlow in the 

 Transactions of the Royal Society of Canada. These rocks 

 ha\e attained a considerable economic importance on account 

 of the abundant development of corundum. The magma was 

 apparently supersaturated with alumina, which, crystallizing 

 out as corundum, has given rise to several new rock types. 

 The rock is further remarkable for its extraordinarily perfect 

 gneissic structure, which, combined with a banding due to 

 original heterogeneity of the magma, causes an extreme and 

 rapid Nariation of composition and a great diversity of types 

 within a short distance. The nepheliue syenites form part of 

 the Precambrian complex of the Canadian Shield, and occur 

 along the borders of batholiths of Laurentian gneiss, where 

 these cut the crystalline limestones of the Grenville series. 



"THE IRON ORE RESOURCES OF THE WORLD."— 

 This magnificent work in two volumes, with an atlas, has just 

 been issued under the auspices of the Eleventh International 



