March i8, 1920] 



NATURE 



87 



caused much damage in the East. It rarely attacks 



very young trees, and develops most rapidly during 



periods of heavy rain. Manifestations ot the disease 



are extremely variable, but a common form, viz. a 



ninlv encrustation on the branches or main stem, 



ves the disease its popular name. Once the bark is 



netrated the fungus spreads rapidly, destroying the 



iirtex, and frequently enters the wood, interrupting 



rlie water-supply to the branches, which turn brown 



and die. So far the best treatment has been the 



removal of infected branches, or by treating the 



diseased parts with tar. Except in special cases, 



N])raying is not practicable. 



In the section devoted to fungal cultures and pre- 

 Ijarations,, the following fungi, among others, have 

 been isolated and grown from the trunks exhibited : 

 Cyphella heveae, a cause of "thread blight " disease ; 

 Botryodiplodia theohromae, a cause of "die-back"; 

 Pontes lignosus ; Hyphomycetes associated with 

 Botryodiplodia. In addition to living cultures of 

 these fungi on potato and banana agars, interesting 

 experiments are in progress with the view of ascer- 

 taining the effect of the vitality of the host upon the 

 potency of the parasite. The fungi have therefore 

 been sown (on wounds) on apple-twigs respectively 

 healthy, of low vitality, and dead, and the cultures 

 kept in a saturated atmosphere and at 25° C. 



The third section well illustrates by means of 

 diagrams the important relationship between the 

 .inatomy of the rubber stem and the yield of latex. 

 In high-yielding trees the bark shows a large number 

 (if rings of latex tubes and a high relative proportion 

 of soft bast as compared with hard bast, which_ latter 

 contains abundant groups of stone-cells interrupting 

 ihe rings of latex tubes. In good yielders the stone- 

 tells are more or less confined to the external part 

 of the cortex; in low yielders they are distributed in 

 depth. The well-known superior yield of tapping cuts 

 made from left to right over cuts made from right to 

 left is due to the oblique course of the latex tubes in 

 the bark. This important fact is explained in a 

 large diagram. Mr. H. Ashplant exhibits elaborate 

 ■statistics showing individual daily tapping yields ob- 

 lained by different coolies on one estate over a period 

 of three years. The figures show that highly skilled 

 tappers working a group of trees previously tapped by 

 average or poor tappers may collect from 50 to 

 joo per cent, more latex than the unskilled men. 

 Ihis fact results from the variable depth of the cut 

 made by the inferior tappers, who do not reach the 

 more internal rings of latex tubes. A further 

 interesting point is the favourable influence of a good 

 tapper's work on the yield obtained by an average 

 tapper succeeding him in the same block. 



It is much to be hoped that efforts will be made 

 to maintain and develop the present exhibition as a 

 permanent museum of the economic mycology of 

 Hevea brasiliensis. Such a museum, with its natural 

 complement of an information bureau, would be of 

 the greatest practical value to the home representa- | 

 lives of planting interests and to the industry 

 p nerally. The exhibition demonstrates in the 

 1 1< arest fashion the supreme importance of scientific 

 - -arch in this vital aspect of rubber-planting 

 w diseases are bound to occur in the future, 

 and it may be disastrous to wait until the 

 plantations are seriously affected before taking stens 

 to secure expert advice. Adequate scientific staffs 

 .should be continuously engaged in studying the com- 

 plete biology of Hevea. so that in the advent of a 

 new disease experienced specialists could be detailed 

 at once to. cope with it. It is, houcvrr. tsscnfial that 

 such staffs should be composed of iik n of fiist-ratf 

 ability and trrnning, for where so much is at stake 

 NO. 2629, VOL. 105] 



anything short of the best is worse than useless. 

 Moreover, the best men afford the greatest chance of 

 effecting the desideratum in combating all disease, 

 viz. the stitch in time. The industry must be prepared 

 to pay for such men, but there can be no question 

 that money generously and wisely spent on these lines 

 would be repaid times over. 



The Position of the Meteorological Office. 



Y)R. C. G. KNOTT, president of the Scottish 

 -•-^ Meteorological Society, has sent us a copv of the 

 following resolution passed by the council ' of the 

 society with reference to the present position of the 

 Meteorological Office : — 



"The council of the Scottish Meteorological Soci<'ty 

 have had under consideration the information pub- 

 lished regarding the future status of the Meteoro- 

 logical Office and its relation to various Departments 

 of State. They recognise that an incorporation 

 in one of the great Departments of State is desir- 

 able, and realise that meteorology has much to gain 

 by an intimate connection with the Air Ministry. 

 At the same time they have in view that the State 

 Meteorological Office has many other departments and 

 interests to serve, not the least of which are those 

 of pure research. They feel that any system by which 

 the policy of the Office was directed by the interests 

 of only one Department might in certain circum- 

 stances hamper its proper development. The science 

 of meteorology made notable advances in manv direc- 

 tions under the liberty enjoyed by the Director of the 

 Office with the administrative committee as con- 

 stituted in 1905. The council urge that, whatever 

 constitution it may be convenient to give to the Office, 

 the public, departmental, and scientific interests of the 

 science should be safeguarded by expressly and per- 

 sonally charging the Director with the care of 

 meteorology in all its branches. Under such an 

 instruction the Director could be relied upon to 

 organise the service upon a scientific plan and to 

 build up the administrative elements in accordance 

 with the demands made upon him. The council also 

 feel that any step which will modifv the functions and 

 responsibilities of the Meteorological Committee 

 should be taken onlv after searching inquirv bv a 

 Departmental Committee into the necessity for anv 

 modification, and the probable effect of such modi- 

 fication on the work of the Meteorological Committee." 



Earthworks and Retaining Walls. 



IT is admitted that our knowledge of earthwork 

 problems is far from complete, and the informa- 

 tion given in two papers read at the Institution of 

 Civil Engineers on February 10 forms a welcome 

 addition. Mr. Ponsonby Moore Crosthwaite has made 

 experiments on the horizontal pressure of sand, and 

 finds that the angle of internal friction is much less 

 than the angle of repose. The experiments show that 

 the pressures on a wall, as calculated from the 

 Rankine and Colomb theories, are much too high, 

 especially for surcharged walls. Further experiments 

 show that the wedge theories which take account of 

 the friction between the wall and its backing give 

 correct results if the wall is not surcbnrfed, but break 

 down for surcharged walls. Rv modifvinf* the wxlge 

 theorv so as to neglect the friction on the hw-k of (he 

 wall, and introdiu ini' th»^ Mnjjle of internal frirtjon 

 instead of the angle of repose, marked Pi^reemont "as 

 found with the experiments for surcharged walls. 



