July i8. 1918] 



NATURE 



385 



LETTERS TO THE EDITOR. 

 [The Editor does not hold himself responsible for 

 opinions expressed by his correspondents. Neither 

 can he undertake to return, or to correspond vnth 

 the writers of, rejected manuscripts intended for 

 this or any other part of Nature. No notice is 

 taken of anonymous communications.] 



Weeping Forms of Trees. 



I.\ Natcre for July ii, on "Weeping Forms of 

 Elm," Mr. W. H. Shrubsole refers to \\vo distinct 

 factors: (i) the "weeping" of the shoots, and (2) the 

 peculiar contorted appearance of the older branch- 

 systems. A fine specimen of the weeping ash, 

 grafted, as usual, standard high on a common ash 

 stock, in the Oxford Botanic Garden, shows a clear 

 • umbrella" of weeping branches, while the head of 

 the tree is a similarly twisted and contorted mass of 

 large boughs. 



The weeping effect is due to weak geotropic sensi- 

 tivity, but to a greater extent to congenital enfeebled 

 response to the action of light. The weeping shoots 

 on bending branches grow out in the direction im- 

 pressed on them in the bud, without any attempt at 

 correqtion, and thus pass out and down, almost ver- 

 tically, as sub-etiolated shoots with very long inter- 

 nodes (a foot or more), the shoot of the current year 

 being as much as 6 ft. long. It is obvious that they 

 cannot go on for ever, as they soon touch the ground, 

 whife they receive the less illumination as thev pass 

 down from the crown of the tree. 



But not all the branches are of this type, as in other 

 freak-forms the normal type of strongly positively 

 heliotropic shoot with erect habit and short inter- 

 nodes (6 in.) is still freely produced. Since these get 

 into the more illuminated regions they progress, after 

 all, better than the others ; and as they twist round 

 on the drooping branches to straighten up, the sur- 

 viving branches of the tree ultimately consist only of 

 such "contorted" shoots, and the central trunk-system 

 takes on the peculiarly twisted mass of boughs. " 



The effect is, however, only an exaggerated expres- 

 sion of the same causes which produce the erecting 

 curvatures in a tree formed of branch-svstems bending 

 down under the weight of their foliage ; and all 

 weeping trees tend to show it more or less, the 

 weeping ash, with decussate foliage and long annual 

 sHbots, perhaps most clearly. To make a more 

 shapely " umbrella," the non-weeping shoots may be 

 cut out, but the tree continues the space-form by 

 natural causes." A. H. Chirch. 



Botanical Laboratory, Oxford, July 15. 



The Mineral Wealth of Germany. 



In Nature of July 4 Prof. Louis criticises my 

 paper, " Germanv's Natural Wealth," which appeared 

 in the Fortnightly Review of June. In that paper 

 I pointed out that the wealth of Germany in coal, 

 iron -ore, and potash amounts to at least 

 240,000,000,000^., taking the value of coal and of 

 potash at Jos. per ton and that of iron-ore at 5s. per 

 ton. Prof. Louis, on the other hand, tries to show 

 that the value of Germany's three principal minerals 

 comes only to 700,000,000/., and asserts that I have 

 overstated Germany's mineral wealth more than three 

 hundred times. 



With all respect to the scientific eminence of Prof. 

 Louis, I am afraid that he has made a great mistake. 

 The value of a nation's natural resources can be 

 estimated either from the point of view of the 

 capitalist, who wishes to exploit mines, etc., for his 

 personal profit, or from that of the nation as a whole. 

 NO. 2542, VOL. lOl] 



A nation has two characteristics. In the tirsL pl.nx, 

 it must be considered practically inimortal. in die 

 second place, it consists not merely of a few capitalists, 

 but of the whole population. From the point of view 

 of the company promoter, the capitalist, or the share- 

 holder the value of a ton of coal in situ is, of course, 

 not los., but only a few ptnct- which form the 

 capitalist's margin of profit, proxided the coal be 

 immediately available, and merely a small fraction of 

 a penny if it be available fifty years hence. Every 

 child knows that. On the other hand, from thr pi)int 

 of view of an undying nation the valur if a ion of 

 coal in situ is, of course, lo*., or wliatever is a fair 

 average price at the pit's mouth; for although 9s. 6d. 

 may be required in wages and expenses to extract 

 that ton of coal, this 9s.. 6d. goes to the nation. 

 Therefore a ton of commercially e.\ploitable coal in 

 situ is worth los. from the national point of view, 

 whether it will be extracted in the present 3e ir (ir a 

 century hence. The same reasoning applies, of coium , 

 to iron-ore and potash. 



My article dealt exclusively with Germany's national 

 wealth from the national point of view. I did not 

 even mention the profit of capital, which is a minor 

 consideration. While Prof. Louis's estimate capi- 

 talises and sums up the immediate value of the profits 

 of capital, my estimate of the value of Germany's 

 minertil resources is taken from the point of view of 

 the nation. Of course, it is absolutely non-per- 

 missible to say, as Prof. Louis does, that the value 

 of a ton of coal is 6d, because that is the capitalist's 

 profit. If coal-mining in Great Britain would return 

 only sufficient to pay expenses, cost of management, 

 etc., the British coalfields, the basis of the country's 

 wealth, would, according to Prof. Louis, be worth 

 exactly nothing, while by my calculation they would 

 be worth ioo,ooo,ooo,oooL 



In view of the probable increase in the price of 

 coal, iron-ore, and potash in the future, my estimate 

 of the value of Germany's minerals was probably a 

 great understatement. Politicis. 



July 6. 



The above comments of " Politicus " are marred by 

 two notable fallacies. In the first place, he holds 

 that my valuation of the minerals is based upon the 

 profit to be derived from mining them. This is quite 

 wrong; my valuation of the coal, etc., in iiiw is 

 based upon the only true criterion of value, namely, 

 the price which it will fetch in the ordinary open 

 market, the sum which those who wish to mine the 

 coal are prepared to pay for that coal in its unsevered 

 condition, i.e. in this country the average royalty 

 which the coalowner can get for it. The profit which 

 those who mine it can make out of it has nothing 

 whatever to do with the valuation, except indirectly, 

 in the sense that coal which cannot be mined at a 

 profit is unsaleable, and therefore has no value. The 

 other fallacy is, perhaps, best shown by pointing out 

 that, according to " Politicus," the unsevered coal in 

 the bowels of the earth is worth as much as the 

 same coal at bank, so that in his view the nation gets 

 the labour and materials expended on raising the coal 

 for nothing! It is surely obvious "that if coal at 

 bank, after gs. 6d. per ton has been spent upon 

 getting it, is worth los. per ton, it cannot be worth 

 10s. before anything has been spent upon it, and that 

 this is equally true whether such expenditure be 

 looked upon as national or as individual. 



The further contention that money realisable in 

 fifty years is worth as much as money realisable to- 

 day is surely not worth discussion ; nations as well 

 as individuals have to pay interest on their loans. 

 According to "Politicus," the i^s. 6d. war savings 



