Dec. I, 1885.] THE TROPICAL AGRICULTURIST. 



2^7 



HOOT STKUOTTTKE. 

 The variation iu the appearance of roots accortUnjj 

 as tliey grow below the surface, in the air, or in 

 water, is well known. Latterly M. Constauiiu has 

 pushed the in»|uiry further and has examined the in- 

 ternal structural mollifications which accomi»any the 

 more obvious external changes. M. Coustantiu examined 

 the structure of the root in terrestrial and in epiphy- 

 tal Orchi.is respectively, and also made comparative 

 experiments by causing aerial roots to grow under- 

 ground, and othei-s exposed to light or immersed iu 

 water, and so forth. M. Coustantm's general conclusions 

 are as follows ; — 



The growth of roots in the air — 1, diminishes the 

 bark, and, on the contrary, increases the pith ; 2, causes 

 an increase in the fibrous system of the bark, as well 

 as of the centre ; 3, causes an increase in the number 

 of ligneous vessels; 4, renders the endodcrmic cells 

 liarder aiul more impermeable. 



When, on tlie contrary, the root developes in water, 

 the following results are apparent: — I, increase in the 

 size of the spaces between the cells; 2, diminutions 

 of the pith; 3, reduction of the fibrous and vascular 

 systems. 



These observations show plainly that the roots adapt 

 themselves in the same manner as do the stems when 

 under different condition*. 



Like the aerial stem, the serial roots are character- 

 ised by the great development of the central cylinder, 

 of the fibrous and vascular systems. 



Like the rhizomes, the subterranean stems are dis- 

 tinguished by the great thickness of their rind, the re- 

 duction of the pith, and the small importance of their 

 fittres and vessels. 



Like aquatic stems, the roots produced under the 

 water are similar in structure to subterranean organs, 

 but dilTer in haviug interceliular spaces, and in the 

 lesser development of the vascular elements. 



The analogy remains even when blancheil stems are 

 compared with roots, which have grown in air and 

 obscurity, the rind and ligneous .system being of less 

 importance than in subterranean organs. The root is 

 therefore as liable to modification as the stem, and 

 if its organisation seems very uniform it is because 

 it is most often developed under the ground. It is 

 to the influence of the medium, terrestrial or aquatic, 

 that we must attribute the feeble development of the 

 pith of roots. The absence of this tissue consequently 

 does not serve to characterise the root anatomically. 

 The most striking result of these experiments upon 

 the ro-jt as well as ou the stem, is that the woody 

 matter is formed with relative difhculty under the 

 ground, iu water, and in darkness. The consequences 

 of this are very important, as the functions of the 

 fundamental tissue and of the endoderm, are tluis 

 found to be entirely altered. — Ganhneis' Clu-vnide. 



ftREEN MANURE. 



TO THE f:DITOK Ol' THE " MADIiAS TIJtKS." 



Sir,^Iu your issue of yesterday you say : " Of the 

 dry coast lands, some we may consider deficient in- 

 deed iu organic matter » » « #^ 

 IJut not all the dry lands in the plains along tlie 

 coast may be deemed deficient in organic matter and 

 re<iiiire green manure." If there is any class of 

 soils in the plains of India which contain more or- 

 ganic matter than others, it is the black cotton 

 soils, as everybody knows. Even these do not contain 

 as much of organic matter as would satisfy an Kng- 

 li.=h or American farmer. A soil containing all the 

 elements of fertility in xery fair proportions should 

 contain about 12 per cent of organic matter at least, 

 and a moderately fertile soil, not less than 5 per 

 cent. Soils containing less than 5 per cent of or- 

 ganic matter are considereil but poor in it in England 

 ami America. In the " Standing Information regarding 

 Administration of the Jladra.s Presidency," riih page 

 204, it has been very rightly remarked of the black 

 soil that '■ it contains very little organic matter, 

 usually not more than 4 per cent." Can there be 

 any doubt, then, that the other kinds of soils contain 



but far less? When I wrote that the black soils 

 are ricli in organic matter, I meant, of course, tliat 

 they are so in comparison with other kinds of soils 

 met with in the plains. The prevailing soils iu this 

 Presidency are light-coloured, which are, of course, 

 extremely deficient in organic matter. It cannot be 

 disputed that in a tropicil climate like this, 

 there is greater need of organic matter in the soils 

 than in England. It nuist also be borne in mind 

 that, while the organic matter in the soils of the 

 Indian plains is uaurally liable to be slowly dissipated 

 by the great heat jirevailing there, the ryot makes 

 matters worse by burning all things which would in 

 England and America go to form vegetable compost 

 anil thus add organic matter to the soil, tlreen- 

 nianuring is really quite as beneficial to the black 

 cotton soils a.s to others which are very poor in 

 organic matter. A vci-y serious defect in the black 

 soils is excessive stillness. One of the best and 

 simplest means of impro\'ing them is greeu-manuring. 

 15y this, very stiff soils, it is well known, are ren- 

 dered looser, and very loose soils, on the other 

 haiul, more stiff. 



If horse gram is to be treateil as a food-corn 

 crop, the best time for sowing it is towards the 

 cessation of the heavy monsoon rains, for instance, 

 about the end of November in flladras and a little 

 earlier in the interior parts. It not sown in its proper 

 seed-time, it cannot mature satisfactorily enough, 

 and is then best tn^ated as a fodder or green-manure 

 crop. It is, ou till- wholly preferable indeed to use 

 the catch-crop for fodder, proxided the ryot eon- 

 serves the dung anil urine of his cattle properly 

 and applies them to his land. But sin<-e the tenqjt- 

 ation to use cattle-dimg as fuel, either through 

 pressure of poverty or through ignorance, is too 

 great for the ryot, green-manuring may be specially 

 reconiraended. In most jiarts of the Presidency, 

 scarcely 5 per cent of the cultivated dry land carries 

 two Ciops in the year, and consequently the ryots 

 and their cattle are idle during a great part of the 

 year. I have shown how the ryot might find useful 

 work for himself and his trattle by growing catch- 

 crops of horse gr.im for fnddi'r or green manure at 

 times when his land woulil otherwise lie idle. 



('. K. SuHu.v R.\o. 



A M.'VLAYAN FOllEST. 



Tropical forest would be a better term than 

 jungle, and less likely to be misunderstood ; for it 

 is a forest of noble trees, mingled with .saplings, 

 tall and slender, growing as closi- as may be. M'hen 

 one tries to analyze the constituents of the mass, 

 the eye soon loses itself in the confusion of stems, 

 vines, branches, and foliage. There are, however, 

 three kinds of tree conspicuous, that is, tall saplings, 

 shorter trees as tall and straight, a. foot or so in 

 diameter, with a green or grey smooth bark ; and 

 finally the large brown heavy stems with ^rugged 

 scaly bark (Dipferocarpus and Dammar Pines). Prom 

 the latter hang loose swinging vines of every size, 

 from the thickness of twine to stout hawser, some- 

 times leafy, sometimes like loose cordage, or the 

 tangled rigging of a ship. Then the leaves are of 

 every shape — minute or immense, opening like huge 

 und)rell!is, or spreading in feathery sprays like a 

 mist over the water. 



I must not omit to mention that .several of the 

 fruits are very ornamental. The crin\son Modecca 

 is just like a large Capsicum ; the fruit of a Dysoxylon 

 like an Orange, whilt: the open seod-pods of some 

 Pithecolobiums equalled any flower in brilliancy. 

 The i\Ialays biought us iu wild fruit such as Mango- 

 steens, Lunsats, and some wild Orapes, but none 

 very savoury ; indeed, some of the party suffered 

 nuich from a burning throat and tongue after eating 

 the Grapes. 



I'or vegetables we had Yams (Dioscorea) and the 

 white inner leaves of a Cabbage Palm, which was 

 very agreeable when cooked, besides the stalks of 

 the Begonia leaves already inferred to. AU the 



