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or indirectly, by planting them on unfavourable sites which allow their growth, but not the na- 

 tural development, of which they might otherwise be capable. So far as our knowledge of the 

 influence of chemical composition upon wild vegetation extends, we have only the fact before 

 us that certain chemical elements act injuriously upon certain plants, while to others they are 

 a newssity. The substances which especially influence vegetable growth are lime, silica, 

 alumina, common salt, sal-amouiac, alkalies, and possibly iron (in laterite), and still more so (as 

 fichleiden has pointed out) water. The influence of these (water excepted) only becomes con- 

 Upiouous, if present in large quantities and distributed over a large tract of land. The above 

 named ingredients in connection with a greater or lesser degree of permeability, will form the 

 basis of all questions in forestry relating to soil. Perennial, and more especially woody, vegeta- 

 tion is more affected by these than herbaceous growth ; but a change through decomposition may 

 produce apparent exceptions which are not always easy to understand.* Then we have before 

 us the fact that by far the greater number of plants mayf grow on almost every substratum, 

 without being peculiar to it, or being permanently settled on it Hence it is difficult 

 to a mathematically trained mind to conceive the practical importance of this ques- 

 tion, which is not so much concerned with the possibility of making a plant grow 

 on a certain soil, as with the prevalence of the plant and the healthiness or luxuriance of its 

 growth on such a soil, on a peculiar soil, as iu its prevalence or better growth on 

 such soil. The soil question is, in my opinion, of great importance to a practical forester.' 

 For instance the " sha" {acacia catechu) tree occurs in Burma on alluvium, is found sparingly 

 on silicious sandstone and forms whole forests in good condition on calcareous sandstone : the 

 natural lesson to be learnt from such a distribution would be to plant sha on calcareous sand- 

 stone, but not on alluvium, although it may, and really does, grow ou it. According to Dr. 

 Brandis, the sal-tree grows best on permeable (coarse-grained ?) sandstone ; if we wish there- 

 fore to have fine-grown sal-timber we should select such a substratum as just named. 

 Or take the case of the Eng tree, which I found growing plentifully ou laterite, sparingly on stiff 

 clay, and calcareous sandstone, but more especially on its ferrugineous decompositions, while a 

 few trees were observed on calcareous alluvium resting on a bed of quartz gravel. It would be 

 very doubtful whether Eng planted on deep alluvium, would succeed there, and if it did 

 grow, it would in a short time lose its power of bearing seeds, and would not, if left alone, be 

 able to maintain itself. 



Unfortunately botanists in India, much to the disadvantage of science, have utterly neg- 

 lected this, and generally the whole soil-question. Climate and geological structure are related 

 to one another to an extent* which still requires to be explained. Under such unfavourable 

 circumstances we have in future to look to the Indian forester for the elucidation of the sub- 

 ject. A wide field it is that spreads itself out before him, one full of interest and practical use- 

 fulness. The scientific spirit which has developed itself amongst foresters in several parts of 

 India, leaves little doubt that we shall soon be as familiar iu India with silica, limestone, etc. 

 loving plants, as people are in Europe, and we shall then discontinue establishing timber 

 plantations on a priori unfavourable substrata. 



Garden and arable soil possess the wonderful quality of absorbing and fixing just those ele- 

 ments most important to plant-life, viz. potash, ammonia, phosphoric acid, and silicic anhydride. 

 Bain is the principal if not sole fertilizer in nature; it contains besides salts, small quantities of the 

 above named substances so necessary for the metamorphosis of otherwise insoluble salts in the soil, 



* An instructive field for illustration of this subject is the calcareous sandstone formation of the Prome district, 

 consisting probably of about 60 per cent, of silica and 35 percent, of carbonate of lime. When in its natural state, 

 it is an impermeable rock, bearing chiefly lime-loving trees of stunted growth, but the same when decomposed, loses 

 all carbonate of lime and becomes a coarse highly permeable siliceous sandstone, bearing silica and lime-loving 

 trees according to the degree of decomposition. The confused distribution of tree-vegetatiou in such a district 

 can easilv be imagined, but is quite explainable. 



t ^^6 cultivate numerous species in our gardens under soil-conditions often diametrically opposed to their 

 natural habits; and theT/ groiv, but every gardener is aware of the number of species that he yearly loses, or which 

 die out, although they did well often for years, thus shewing that not climate but soil is the cause of their decay. 



J 1 will adduce only a single example to illustrate this. The climate of Sindh has always been looked upon 

 as abnormal, when compared, for instance, with that of Lower Bengal. We come across more such drj' districts on 

 the continent often perfectly surrounded by damp regions, such as Prome and Ava, and certain parts of lower 

 Siam. Even in the Indian Archipelago we find the Eastern parts of Java drier than the Western, and Balie, 

 Lombok, Sumbawa, and Timor, excessively dry. Dry winds from Australia are said to cause this, but this cannot 

 be the case. If however we consult the geology of these countries, we find that they consist chiefly of calcareous 

 strata, and the problem therefore approaches solution. 



Dr. Brandis' Rain-map of India (Ocean Highway for October, 1872,) has brought to light the curious fact that 

 the rainless regions of India by no means stand iu direct connection with prevailing air-currents, but form so to 

 gay centres round which zones of increasing humidity are concentrically placed. The moisture of the S. W. 

 winds may really be absorbed by the high Nilghiri hills and cause the dryness of the Hindostau arid centre, but 

 guch would not explain the aridity of Sindh, a chiefly calcareous and saline country. I think, therefore, that 

 the absorbing qualities of salty soils and limestone and their great retentiveness of moisture must be brought 

 into account here. Had Dr. Brandis extended his map eastwards, more such arid centres, from which hot winds 

 arise (with concentric moister zones) would have turned up in Burmah, Siam, and the Indian Archipelago. 

 Capt. Maury (Physical Geography of the sea) docs not take such relations into account. 



