S54 



THE inOPiCAL AdRteULTURi8T« [jtsm h x8S^ 



. ■■■~'---^yJ,i' ,i M-rH | -| ^ii l TIn 



Caoutchouc is much more Widely diffused in the 

 vegetable kingdom than many are aware of. An idea 

 bxi'<ts that any plant which yields a lactescent juice 

 contains caoutchouc. There is an error in such a 

 preposition being too generally accepted, because of 

 the disappointment which follows an unfavourable 

 report ; still, it would be very unwise to assume that 

 any plant yielding a lactescent juice is unworthy of a 

 careful examination for caoutchouc. There seems to 

 me a great want of a reliable method for examining 

 the juices of plants for caoutchouc. It cannot be too 

 forcibly impressed upon those who are interested in 

 this matter, that the recently-drawn sap of a plant 

 should be examined, if po-^sible ; even experienced 

 people consider that caoutchouc is too permanent in 

 its character to alter. When caoutchouc is isolated 

 from resins, oils, and similar principles, it may be 

 kept for a long time, but it would be quite another 

 matter if these were left together for some time. 

 The elaboration of certain principles, or secretions, 

 by liiHiif/ plants, points conclusively to an idiosyn- 

 crasy in plant life which we ought not to ignore. 

 We know that vitality interferes with chemical 

 affinity, by preventing changes due to mere chemical 

 action. 



A few years ago my attention was directed to the 

 curious changes which took place in the medicinal 

 activity of certain plants under cultivation, as com- 

 pared with the same plant growing as it were on its 

 own natural soil. Chemical analysis of the soil and 

 plant revealed the fact that nitrogenous matter was 

 wanting. The mineral ash of a plant gives a fair 

 idea of what is required in the soil so as to be favour- 

 able for its growth, but we must look to the sap of 

 the living plant to know how far climate and other 

 meteorological surroundings are suitable for a healthy 

 and vigorous growth. An abnormal development 

 of any part of a plant must be avoided if we wish to 

 maintain its original integrity. 



Warm climates are more favourable to the pro- 

 duction of milky juices than cold climates. From 

 this we may conclude that, in order to arrest rapid 

 evaporation from the plant, which would of course 

 involve exhaustion, certain principles are developed 

 whose function is by its emulsive action to retain the 

 water, or to impede its evaporation, we must not 

 overlook the fact that excessive evaporation, per se, 

 is injurious to a plaut, but the cooling action due to 

 rapid evaporation, has the same influence as tran- 

 sferring a plant to a cooler region. 



lu such cases, currents of dry air are productive of 

 muoh mischief; moist air has httle or no effect on 

 evaporation. When the cultivation of india-rubber 

 plants was first mooted, the idea was to work on the 

 plaut yielding Para-rubber, and considering the state 

 of our knowledge at that time, the error of judgment 

 was pardonable, still it is by no means improbable 

 that the effort to raise the Para-rubber yielding plant 

 may be again attempted. 



I have often been struck with Faraday's analysis 

 of India-rubber juice, which was, I believe of Indian 

 origin. The omission of ammonia, if present, could not 

 have been passed over by such a careful observer.. 

 More recently, in examining india-rubber juices, I 

 find that ammonia is by no means a constant in- 

 gredient in these juices. When a Juice has been 

 coagulated, the caoutchouc which separates out cannot 

 be 'redissolved, but if ammonia be added previously, 

 the caoutchouc remains blended in an emulsive form. 

 If the juices become acid in anyway, the cautchouc 

 separates out. The only juice I have examined which 

 contains a large quantity of free ammonia is that 

 obtained from the Syphonia dastica, grown in Para, 

 and it would be extremely interesting to know 

 whether, when the plant is raised elsewhere, this 

 ammonia is present. The juice of the Masaranduba 

 (Cow-tree), although as rich in caoutchouc as the 

 Syphonia dastica, 'and quite as good as regards 

 quality, is not only free from ammonia, but remained 

 for some months quite fluid. This juice wan also 

 gathered at Para. A point of singular importance 

 connected with the cultivation of the f^yphunia dastica, 

 is the fact of its juice being 90 rich in a uitrogeu 



compound, when we know that the soil itself 

 is neither manured nor supplied with nitrogen 

 in any form, so far as we can tell. AVe are driven 

 to the conclusion that the atmosphere contributes 

 nitrogen to the plant. 



This brings us to the consideration of the meteor- 

 ological conditions under which the Para india-rubber 

 plant grows, and will help u.s to explain why it is 

 that this plant will not grow productive of caout- 

 chouc, even when transplanted to the same parallel 

 of latitude. During the evening, and greater part 

 of the night, it is curious to note the vivid lightning 

 which plays almost incessantly among the trees along 

 the Para river; there is a decided absence of that 

 violence which characterises a thunderstorm ; in fact 

 if rain sets in, it is almost invisible. Do these 

 silent elective discharges in warm, damp air, assist 

 in generating ammonia y If it is impossible to trans- 

 plant the Si/phonia dastica to a suitable climat«, 

 with the meteorological accompaniment as found at 

 Para, we are certainly justified in trying an experi- 

 ment by supplying it with ammonia in some form, 

 so that under the influence of vegetation, it may 

 approach the assimilative action of what nature 

 supplies to the Para plant. I am comvinced that iu 

 some parts of our colonies, we may reasonably expect 

 that rubber cultivation can be successfully carried 

 out. 



The Mangabeira (Mango -tree) and Masaranduba 

 (Cow-tree), are worth experimenting on, as their 

 cultivation do not require anything particularly 

 special but what an ordinary grower can supply, 

 of course a suitable climate being granted. 



Analyses and general descriptions of the soils on 

 which caoutchouc producing plants are grown, are 

 indispensable, as from them any soil to which a 

 plant may be transferred for cultivation, can be 

 selected or made up so as to represent the natural 

 soil on which it previously grew. This assistance 

 would help to relieve an intending cultivator from 

 the onus of delay iu fruitless experimental trials and 

 expense. 



Tnis would be a very simple matter, as our 

 foreign Consuls would have no difiiculty in procur- 

 ing authentic samples of the soil and of the wood 

 of the rubber plant raised on it. — Journai of the 

 Society of Arts. 



♦ 



MOTHER-OF-PEAEL FISHERIES IN THE 

 RED SEA. 



Consul Jago, of Jeddah, says that the mother-of- 

 pearl fisheries extend the whole length of the Eed 

 Sea, from El Wedj on the Xorth, to Aden on the 

 South. The principal grounds are in the neighbour- 

 hood of Suakim, Massowah, and the Farsan Islands. 

 About 300 boats are employed, the majority belonging 

 to the Zobeid Bedouins, a tribe of Arabs inhabiting 

 the coast line between Jeddah and Yambo. 

 About fifty boats belong to Jeddah, and two or three 

 to Confida, Cameran, and Loheiha, They are open, 

 undecked boats of between eight and twenty tons 

 burden, carrying a large lateen sail, manned by 

 crews varying between five and twelve men, and each 

 provided with a number of small canoes, which are 

 imported specially from the coast of Malabar, There 

 are two fishing seasons during the j'ear, one of four 

 months and one of eight monthsj during nearly the 

 whole of which the boats keep the sea, the crews 

 living on board, returning to their homes for short 

 periods of two to four weeks. The crews, composed 

 priucipallj' of black slaves, are paid by share of the 

 produce of their fishing, the owner of the boat taking 

 one-third, the remaining two-thirds being divided 

 among the former, after deducting the cost of food 

 consumed by them during the voyage, and which 

 consists of ilhourra, rice, and fish, with sometimes 

 a little ghee and dates as a luxury. Fatal accidents 

 are said to be unknown, and the men are remark- 

 able for their strength and good health. They dive 

 betw>. u the ages of ten and forty, and the practice 

 is said to have no ill effects. The fishing takes 

 place iu the neighbourhood of reefs, the boat an- 

 choring at a certain spot^ wbecce the crew proceed 



