Vol. X. No. 251. 



THE AQKICDLTURAL NEWS. 



399 



larly creasoted in many parts of the tropics, and of temperate 

 countries. An instance of the value of creasoting telephone 

 posts, as demonstrated in Antigua, is given in the Agricultural 

 JVeics, Vol. IX, p. 377. There, creasoted telephone posts 

 have been in use since 1896, while at present they numlier 

 over 1,000. Only a few of these have required replacing, 

 while the majority are sound. Untreated posts only last 

 from three to four years. A way of using creasote for pre- 

 serving gate posts, which is under trial in Antigua, receives 

 attention in the Af/rimltural News, Vol. IX, pp. 312 and 

 377, and in the Annual Report of the Botanic Station, 

 Antigua, 190910. Another advantage of protective treat- 

 ment is that inferior timber, as long as it is well seasoned, 

 when treated in this way, may be employed in the place of 

 more e.xpensive material, and will last as long. In view of 

 these advantages it is remarkable that protective methods are 

 not more in vogue in the West Indies, though this may be 

 partly accounted for by the fact that the methods themselves 

 as well as the protective substances are not yet as perfect as 

 they might be. Future work will probably bring about 

 a considerable advance in these respects. 



THE EXPLOITATION OB' 

 MANGROVE BARK. 



An article on this subject appeared in the Agricultural 

 News, Vol. VIII, p. 309. The information contained in this 

 may well be supplemented by part of that which is available 

 in the Journal d' Agriculture Tropicale for September 30, 

 1911, p. 257, which gives attention to work that has been 

 done in relation to the matter in East and West Africa. This 

 states firstly, that the exploitation in the first-mentioned part 

 of Africa commenced on the Mozamljique coast, with Ibo as 

 the place of export. In 1 903 purchase of the bark was begun 

 at Nossi Be, Madagascar, and the prices obtained in Hamburg 

 ranged between £5 13s. and £6 9s. per ton — a rate which, it 

 is considered, should prove of equal advantage for similar 

 exportation from West Africa. The industry has extended, 

 and in 1909 the exports from Madagascar reached 15,295 

 tons. 



The collection of the bark in Madagascar is made under 

 the direction of Europeans, who pay a fee to the Government 

 for the privilege. The bark is dried bj' simply spreading it 

 out on the sandy areas that exist in the mangrove forests. It 

 is worthy of notice that, unlike the varieties in West Africa, 

 the kinds of mangroves in this island are hardly ever found 

 growing in anything but mud. The bark was obtained from 

 the largest trees, at first, and the average tannin content was 

 then 42 per cent.; it has since fallen to 40 per cent., and is 

 now reckoned at 38 per cent., as the best trees have almost 

 all been exploited. 



Numerous applications for concessions for bark-collecting 

 have been made in French Guinea: but little has been done 

 other than the exportation of wood for telegraph posts. The 

 French tanning factories have commenced, although late, to 

 interest themselves in the product from French Guinea; and 

 it remains for the tanning content of this to be determined 

 before it can be decided if the export will be remunerative, 

 especially in the light of recent lowering of prices. 



Attention is drawn to a note in the Kolonial Zeitschrift, 

 in which it is pointed out that the mangrove in the Cameroons 

 has not been exploited, becau.se the bark only contains 25 

 per cent, of tannin, as compared with the tannin content of 

 the East African varieties, which reaches as much as 45 



per cent. Another disadvantage is that the continual wet 

 weather experienced in the Cameroons renders impossible 

 economic drying of the bark, and causes decomposition in 

 the latter during transport. The remedy for this is suggested 

 in the preparation of the extract of the bark in the country 

 itself. 



The value of the wood of various kinds of mangrove 

 differs considerably; a characteristic of that in West 

 Africa appears to be extreme hardne.ss — a property 

 which makes the cutting of the tree a matter of great diffi- 

 culty, and has suggested the employment of the Sautke 

 sy.stem for felling the trees; this consists in encircling the 

 trunk with a metal band which is moved to and fro while an 

 electric current is passed. In the experience of the writer 

 of the article from which this information is being taken, 

 the trunk of the tree .should be supported while it is being 

 felled; and when it has once been cut, it should be placed so 

 as to lie on the roots of neighbouring trees, as otherwise it 

 will sink into the mud, and be lost. The wood of the West 

 African varieties of mangroves, as the consequence of its 

 hardness, appears to be best adapted for making piles and 

 railway sleepers; no information can be given as to its use- 

 fulness for making telegraph posts, as a result of the trials 

 mentioned above is not yet available. In connexion with the 

 employment of the wood for railway sleepers, its weight would 

 appear to make it useful; but the effect of sunlight and heat 

 on the wood has not yet been determined. The largest pro- 

 portion of mangrove wood is of too small a girth for the 

 purposes mentioned, but there are doubtless many ways in 

 which this could be employed, on railways. 



In New Caledonia, applications for mangrove cojices- 

 sions have been made to the Government, but the Chamber 

 of Agriculture has opposed these on account of the fear 

 that the removal of the mangroves from the coasts would 

 promote erosion, and would take away the shelter that they 

 give to the cocoa-nut plantations. At the same time, .success- 

 ful exports of mangrove products have been made from 

 New Caledonia, and it is proposed that a tanning factory 

 .'ihall be erected in the country, the promoters of which will 

 promise to keep the cutting within reasonable bounds, and 

 to plant two trees for e\'ery one taken away. As far as New 

 Caledonia is concerned, it is not expected that the project 

 will go forward, on account of the opposition, mentioned 

 above, of the Chamber of Agriculture. It is pointed out 

 that, nevertheless, there is no reason why mangroves in 

 other countries where they grow in large quantities should 

 not be exploited, through the efforts of the principal buyers 

 and the encouragement of direct sales on the part of the 

 natives of tho.se countries. 



One of the most recent conclusions in respect to the 

 investigation of pellagra is thus stated by .Or. L. W. Sarabon, 

 in the Journal of Tropical Medicine and Hygiene, Vol. XIII, 

 Nos. 18 to 21: 'The many analogies existing between the 

 epidemiology of pellagra and the best known insect-borne 

 diseases; the constant association of the disease with Simu- 

 liuminfested streams; the absence of any other arthropod 

 with similar distribution that might account for it; the 

 striking correlation between the fly and the disease in wide 

 geographical distribution, peculiar topographical exigencies, 

 extraordinary double season activity, the marked influence 

 of temperature, heavy rains, and inundations; are all facts 

 which .strongly point to Simulium as the necessary carrier 

 of pellagra.' 



