JdKC. 1, 1BH6.J fUn rnOPtCAL AGRICULTU^ISf„ 



407 



which is boiled in its own husk with so much Aji 

 aud surpass iu flavour and jjleasantncss any vugo 

 tablc curry of the Kast. The CJourds of Aji when 

 thoroughly ripe are cleansed of their coating of clay, 

 tied up in suitable leaves, well secured by the fibre 

 of the Aloe, and which much resembles when ready 

 for market reeves of large onions, a dozen Gourds 

 making up one reeve of Aji. The cost of these iu 

 the good old times was 15d. for a dozen Gourds ; 

 what the price may be now is only known on 

 the Exchange." From the references made iu the 

 preceding passage to the pods and seeds beiug ground 

 to constitute the Pepper, it will be readily guessed 

 that it is the produce of a species of Capsicum, not- 

 withstanding that the writer of the article says it is 

 " not the Capsicum baccatum, nor the C. fruticosum, 

 nor the C. annum." In the Kew Museum are 

 numerous varieties of the fruits of Capsicum annum, 

 all bearing the name of Aji, and the museum also 

 contains specimens of the small Gourds filled with 

 Capsicum Pepper as described by our contemporary; 

 so that the " Aji-Aji" of the Saturday Beview is clearly 

 the produce of Capsicum annum. — John R. Jackson, 

 Curator, Museum, Eoyal Gardens, Kew. — Gardeners' 

 Chronicle. 



BOOTS. 



{Co/tduded froiib p. 388.) 



Many plants flourish in an open soil with plenty 

 of sand in it, but will not grow in a stiff wet soil. 

 This is not necessarily because the heavier soil does 

 not contain the right food materials, but because 

 its particles are so small, so closely packed, and 

 so retentive of moisture, that the root-hairs do not 

 obtain sufficient oxygen : moreover, the very dimp 

 state of the soil does not favour the development 

 of the numerous root-hairs necessary, as we have 

 seen. Nor is this all — though I cannot here enter 

 at length into this point — root-hairs and roots cannot 

 grow or act unless the temperature is favourable, 

 and we have plenty of evidence to show that a close 

 wet soil may be too cold for the roots at a time 

 when an open drier soil (exposed to similar con- 

 ditions as regards sunshine, &c,), would be of a tem- 

 perature favourable to their growth. Many a pot- 

 plant receives an overdose of water because it is 

 drooping from the roots, being too cold to act 

 properly. The opening up of stiffer soils by means 

 of the spade or plough, or by the addition of other 

 kinds of soil, such as sand, burnt lime, &c., or by 

 means of drainage of various kinds, is thus to be 

 regarded as a means of letting in air, and therefore 

 oxygen, to the roots. " Sweetening the soil " is an 

 expression one hears used by planters and others ; this 

 is often no doubt their way of expressing the fact 

 that the air thus let in does so much to turn the 

 noxious substances which have accumulated into other 

 substances which the root-hairs of the plant can 

 take up with profit. The exposure of certain soils 

 to sharp winter frosts in part benefits the plants 

 subsequently grown in it, because air can make its 

 way into the cracks produced as the particles crumble : 

 there are other advantages also due to the" weathering" 

 of soils, of course, as also to the addition of lime, 

 &c„ but I am purposely abstaining from referring 

 to points concerning the nutrition of plants as generally 

 understood. 



Let me shortly call your attention to a few other 

 practical applications of the knowledge briefly summed 

 up above, It is well known that a good deal of 

 experience has been brought to bear on the question 

 of what trees are the best to plant iu or near large 

 towns: there are very many facts to be considereil. 

 It is not sufficient to find a tree which will accommo- 

 date itself to the possibilities of the annual rainfall, 

 or a diminished supply of sunlight throughout the 

 year, and so on; nor is the problem solved when a 

 tree is found that will put up with traces of acid gases 

 in the atmosphere, and, as may follow, the accunud- 

 atiou of acids in the soil, and consequent alteratious 

 in its chemical composition. In many cases trees 

 bare beeu fouud to die as tbey grew oldgr becauise 



the pavement or asphalt over their spreading root- 

 system prevtnted proper ac'iatiuu and a proper supply 

 of aerated water to their root-hairs ; imagine the 

 elfect of a few days' hot summer sunshine on roots 

 just beneath the pavement of an exposed street ! 

 it is true the cover may prevent rapid evaporatiou, 

 but it also shelters the soil from the well aerated 

 raindrops ; moreover, such sheltered roots will at 

 certain seasons grow up to the surface of the soil 

 and in contact with the lower surface of the pavement. 

 Then thtire is the question of drainage. If the water 

 which does find its way in slowly accumulates and 

 becomes stagnant, the results are as disastrous or 

 even more so ; yet it is obviously a difficult matter 

 so to arrange things that the accumulated surplus 

 water of certain seasons shall pass away below, acting 

 like a suction-pump and drawing in air after it, and 

 still fulfil the other requirements hinted at above. 

 I leave out the question of exhaustion of the soil — 

 the dead leaves, &c., being carefully removed. Can 

 we wonder that there are so few trees to choose 

 from that will stand such treatment? The fact that 

 there are some only accords with what has been 

 already stated — that plants vary iu their requirements 

 and powers ; and no one doubts that the variations 

 have been influenced by variations in the environment. 



We have now seen to a certain extent how variations 

 of a particular kind may affect a plant. The plant 

 responds to a certain extent — it is, as some people 

 say, "plastic" — but if the limits are reached and 

 s'ightly overstepped, the variations on the part of 

 the plant become dangenus to its existence, and 

 the plant becomes diseased and may die. 



Not to dwull upon hypotheUcal matters, I will 

 content myself with saying, in conclusion, suppose a 

 variety of a given plant grows in damp places and 

 has roots which form few or no root-hairs, and suppose 

 an individual of that plant to become transferred 

 to a more open soil ; I have shown you reasons for 

 regarding it as probable that the latter individual 

 might produce more root-hairs and thus adapt itself 

 to the altered conditions. If such a case happened, 

 it is by no means improbable, but the contrary, that 

 other circumstances co-operating or adverse would 

 decide certain problems of importance to the existence 

 of that particular indiviLJual. 



But the main oliject of this lecture has been to 

 show you how very complex the conditions may be 

 which bring about a " tliseased " condition of the 

 roots. It is no uncommon event to see a tree flourish 

 for years and then die slowly off from " some- 

 thing at the roots ; " examination shows that the soil 

 still contains the necessary foods, the water-supply 

 is constant and good, the tree is exposed to no ob- 

 vious adverse influences, and yet with steps so low 

 that they are scarcely noticeable, the tree begins 

 to die off before its time. In some cases this is 

 probably because the root-hairs are not receiving 

 their proper supply of atxuospheric oxygen, and this 

 may be due to very slight changes in this structure 

 (not the chemical composition) of the soil: a very 

 slight diminution in the activity of the root-hairs 

 may cause a diminution in the nupply of water to 

 the leaves at seasons when they rtquire much, and 

 this mems lessening their supply or food-materials. 

 If the leaves are placed on short comraous they 

 cannot form wood, and so the next season's supply 

 of nutritive solutions may be cut short; moreover, 

 fewer root-hairs will be formed. No doubt differ- 

 ences will appear in different years or seasons ; but 

 if the tendency on the vvhole is in the above direction, 

 the life of the tree is already limited — it may drag 

 on for years as an object, which can scarcely bo 

 termed a t^ee, however, but its doom is sealed. 



The difSculty of placing one's hand on an exactly 

 illustrative case is due to the fact that other causes 

 are usually at work after a short time. I have 

 purposely avoided any reference to the changes brought 

 about in the chemical nature of a soil by the addition 

 or cutting off of air, &c., ; and for the same reason 

 — to keep your attention directed to the root-hairs 

 as living cells exposed to the influence of a defi- 

 uite environment— I have left out of account soni^ 



