176 



NATURE 



[May I, 1919 



abstracts in German, French, or . English, 'Jhese 

 memoirs are profusely illustrated, and replete with 

 statistics, tables, diagrams, and maps. 



To the British forester the most interesting of these 

 studies is the monograph on the cultivation of the larch 

 in Sweden by Prof.. Gunnar Schotte, which takes up 

 pp. 529-840, followed by twenty-six pages of biblio- 

 graphy, enumerating the books and articles on the larch 

 in various languages. The botanical part is excellent, 

 but the great merit of the work lies in the admirable 

 account of the sylviculture of the three species which 

 are grown in Sweden. Of the European larch forty- 

 two experimental plots have been exhaustively studied, 

 and most of the conclusions arrived at are applicable to 

 British conditions. Prof. Schotte only approves of pure 

 woods of this species on exceptionally good soils. He 

 recommends a mixture of European larch with pine or 

 with beech on moderately good to medium soils, and is 

 convinced that larch should never be planted on poor 

 ground. For the prevention of canker due to Peziza, 

 which is the scourge of this species in Sweden as well 

 as in England, he advocates early, frequent, and heavy 

 thinnings, with the object of removing the feeble and 

 suppressed trees, which are liable to be attacked by 

 the fungus. The Siberian larch, which is comprehen- 

 sively treated, is successful in Sweden, but quite 

 unsuitable for our climate. Sample plots of Japanese 

 larch in Sweden are still young, but so far this tree is 

 extremely vigorous and immune from disease. Prof. 

 Schotte 's' article, which is accompanied by an abstract 

 in English, is followed by a report (pp. 841-922) of 

 an elaborate investigation by L. Mattsson on the form 

 of the stem of the larch. The results, which are 

 highly technical, are also given in an English abstract. 

 A similar investigation (pp. 9-1 10) by Nils Sylven 

 of the variety of the common pine which is in- 

 digenous in northern Sweden is of considerable 

 interest. This tree, distinguished by some botanists 

 as a separate species, Tinus lapponica, differs mainly 

 in its more slender pyramidal crown of foliage and in 

 its thinner bark. The plate showing the variations in 

 the form and colour of the seeds and cones of this 

 variety and of the common pine is beautifully drawn. 

 The germination of the seed of the northern pine is 

 dealt with by E. Wibeck in a memoir (pp. 201-34). 

 The insects which attack the cones of the pine and 

 of the spruce as well, and the peculiar fungus, 

 Melampsora pinitorqua, are dealt with in separate 

 articles (pp. 1077-1204). 



The composition of forest soils and the formation 

 of humus have been investigated by H. Hesselman 

 (pp. 297-528 and 923-1076). Mr. Hesselman distin- 

 guishes mild humus usually found in broad-leaved 

 forests, and raw humus characteristic of most coni- 

 ferous forests. In the latter no nitrification ordinarily 

 takes place, and natural regeneration is rendered 

 difficult by the feeble growth of the seedlings in the 

 absence of nitrates. He also points out the measures 

 which can be adopted to transform the raw humus, 

 such as partial felling, which admits light on the 

 ground and brings about a radical alteration in the 

 bacterial f^ora. The change undergone by the 

 humus is accompanied by an alteration in the ground 

 vegetation. When the nitrogen is transformed into 

 nitrate, plants like raspberry, Epilobium angusti- 

 folium, Senecio sylvaticus, etc., appear. In the 

 absence of this transformation, Aira flexuosa is the 

 predominant plant in the clearings of the forest. 

 Hesselman 's investigations are of considerable interest 

 to ecolojjists. 



The fifteenth volume of the memoirs, just received, 

 contains a number of miscellaneous articles : on a 

 new plough designed by Mr. Widen ; on the seed crop 

 of the principal trees of Sweden during 1917; on the 

 attacks of the more important insects and of the 

 NO. 2583, VOL. 103] 



fungus Melampsora pinitorqua during the same 3'ear; 

 and on a new method of ascertaining the form' and 

 volume of single stems of spruce. The programme 

 of the investigations to be carried out by the institute 

 during the triennial period, 1918-20, is also given. 



M 



PLANTATION RUBBER RESEARCH. 

 ESSRS. EATON, GRANTHAM, AND DAY 

 have published (Department of Agriculture, 

 tederated Malay States: Kuala Lumpur) an account 

 of important researches carried out in Kuala Lumpur, 

 Malaya, during the last three and a half years in con- 

 nection with the preparation and vulcanisation of 

 plantation rubber. The Bulletin runs into 398 pages, 

 and gives one .of the most detailed accounts of rubber 

 research in Malaya yet published. The authors point 

 out that they, as Government officials, are working 

 under difficulties in so far that, whereas they give full 

 publicity to their methods and results, they are pre- 

 cluded from gaining knowledge of the methods 

 adopted or apparatus used by other technologists in 

 Malaya and London who are carrying on similar 

 experimental work with rubber. It is clear that the 

 policy of secrecy adopted by companies and associa- 

 tions which privately employ chemists and mycologists 

 in the East is open to very grave objection. The 

 policy of secrecy is not only against the true scientific 

 spirit, but must also, in the long run, seriously reduce 

 the value of research even to those who privatelv 

 employ their own technologists. All scientific work 

 should be open to criticism based upon knowledge of 

 the method and apparatus employed. The present un- 

 satisfactory arrangement may work well enough for 

 privately employed technologists who have the advan- 

 tage of studying detailed accounts of methods em- 

 ployed by Government officials ; the reverse, however, 

 is obviously not the case. 



Considerable energy appears to have been thrown 

 into the researches on variability of plantation rubber, 

 a subject which raises hostility among owners of 

 plantations who consider that their finished product 

 cannot be improved upon. We have never agreed 

 with those plantation producers who refuse to believe 

 in the variability of plantation rubber, and the fact 

 that they have introduced the word "uniformity" in 

 a comparative sense does not blind us to the real 

 position. 



The authors, as a result of their work, believe that 

 the ordinary forms of smoked sheet and crepe, now 

 so common in the markets of the world, will be super- 

 seded by a new type of rubber turned out in "slabs." 

 If it is true that the rubber prepared in slabs is 

 superior to the common forms now produced, a great 

 advance will have been made. 



The problem of vulcanisation has been investigated 

 in an unusual direction. It is claimed that in con- 

 nection with organic vulcanisation accelerators a dis- 

 covery has been made which ranks only second with 

 the original discover}' of vulcanisation by Goodyear and 

 Hancock. The authors have demonstrated that valuable 

 vulcanisation accelerators are present in Hevea latex, 

 andean be formed by special treatment of the coagulum. 

 A number of vulcanisation accelerators were sent bv 

 the present writer to these investigators in 1915 ; 

 they appear to have led to an interesting line of 

 research which should have far-reaching results. The 

 discovery of the vulcanisation accelerators in Para 

 rubber was made prior to the authors' knowledge of 

 the discovery and use of patent organic accelerating 

 agents. The accelerator found in rubber is said to 

 be produced by the decomposition of the proteins, and 

 td consist probably of an amino-acid or amine. The 

 substances found in plantation rubber are responsible 



