r.ErOIiT OF CHEJIICAL LAECrATOKY 225 



" Excessive moisture in soil, otherwise suitable, appears to prevent the production of Conditions 

 eum. Near Agari, where the Khor Agari loses itself in the sandy soil, there is a good f^*™'''"" ?>"" 



" ^ o J ' >D production 



growth of Hashal), but on these trees no trace of gum was found, though on either side 

 there is good gum producing Geneina. Trees on such moist soils preserve their leaves, 

 and it seems probable that shade is in such cases, the main cause preventing the formation 

 of gum, just as the flush of new leaves, when the rains commence, stops the further 

 production of gum for the season, on gum bearing trees. 



" Protection from fire is essential to success. Burnt Geneina is unproductive for the 

 rest of the season. This is known, and acted on by the people, who are extremely cautious 

 in the use of fire, so that although they do not take more active measures of fire protection 

 only a comparatively small area of burnt Geneina was seen. 



" The main causes of such fires as do occur, seem to be the careless burning of grass 

 on the paths by camel men, and malicious firing by gum pickers (living in villages not 

 frequented by gum merchants) of Geneina, near the villages at which the merchants reside 

 during the gum season ; the object being (by lessening the supply of gum at the latter 

 places) to induce the merchants to move on to the other villages. 



" The clearing of fire traces would safeguard the Geneinas from accidental fires, and 

 would render the detection of malicious firing less difficult, as incendiaries would have to go into 

 the Geneinas to set fire to them, instead of merely lighting the grass to windward at a 

 distance. Adequate punishment in proved cases of malicious firing is the only means of 

 stopping the offence. Regarding the age of gum producing trees 3 to 15 or 20 years may 

 be taken as the limits ; the lower limit is essentially one of size rather than age. Young 

 Ha»hah 8 to 10 feet high, with a girth of 6 to 8 inches, will produce gum. 



" From an examination of trees in various localities which were producing little or no 

 gum, and in Geneinas considered past bearing, it appears that at about 12 to 15 years of 

 age the Ilashah tree forms a dark brownish black heartwood, and thereafter the production 

 of gum diminishes, and subsequently ceases. Probably trees of 8 to 12 years yield the 

 best return of gum. 



" Much might be done to increase the production of gum by filling up blanks in Geneinas. 

 It would be easy to collect seeds from the other trees in the Geneina, and drop them 

 about at intervals of six yards in the blank spaces. Such sowing had best be made just 

 when the rains commence, so that the seeds may germinate as soon as possible after 

 sowing — if made earlier many of the seeds would be eaten by rats. 



" Crowding of trees in a Geneina is not desirable, as it is gum, and not timber, that is the 

 marketable produce. A complete canopy would give too much shade and lessen the exudation 

 of gum, also a much-branched tree has a proportionately greater gum-bearing surface. 



" A stock of 18 to 100 trees per acre would be dense enough, and sowings as indicated 

 above would (allowing for failures) produce sufficient seedlings. 



" In addition to the advantage of maximum yield obtained by having a fully stocked 

 Geneina, the risk of serious damage by fire is much less than where trees are scattered, and 

 the absence of shade allows a thick growth of grass to spring up. 



" As population increases, areas of Wady will come to be treated as Geneina, yielding 

 a purer gum and more of it. 



" The management of Geneinas is best left in private hands, the operator is then directly 

 interested, and uses all care in the barking of the trees and the collection of gum. 



" The present needs are more people to take up Geneina, and wells to enable them to 



