646 F.XPKHIMKXT STATION RKC"OHD. 



flow of latex is almost tlu' saiin" tliniuj;ln»ii( tlic morning li<>ufs. The taiipinj; 

 work as a whole iiitlu-ntos lliat iiiulcr ordiuai-y ciiiKlitioiis it will 1k' i)r<ililahl»' 

 to tap trees from daylight until nearly noon. 



A further test was made of rlu? use of water-ba^'s tu wash down the latex. 

 Although it appears that the yield may )><' somewhat iiicrease<l and the flow 

 maintained for a somewhat longer lime by the use of water, the economy of 

 the operation has uot as yet been determined. 



It appears that the flow of latex may be temporarily stimulated by api)ly- 

 ing nitrate of soda. In one case the nitrate wa.s placed in the soil at a dejith 

 of 3 or 4 in. and at some distance from the trunk around each tree where it 

 would most quickly l)econ!e available to the roots. The weight of dry rul)ber 

 from 3 trees which received ; lli. of nitrate of soda each was 2.3 oz., from 3 

 trees receiving I lb. each 1.3 d/,., and from the 3 unfertilized trees 1.2 oz. The 

 effect of the nitrate of soda upon the flow of latex was manife.sted within 4S 

 hours. The test was repeated with similar results. 



Experiments in retapping trees which have recently been tai)ped indicate 

 that the Ceara rubl)er trees in Hawaii may be proHtably tapped about 3 times 

 annually. A study of the distribution of the latex tubes shows the tubes to be 

 found almost exclusively in the bark outside of the cambium, so that it apjiears 

 unnecessary to injure the cambium. The large number of connecting tubes l)e- 

 tween the main longitudinal trunk is couspicuous and accounts for the ready 

 flow of latex from the tapping wounds in any direction. The use of inter- 

 crops, such as corn or soy beans or other legumes while the trees are maturing 

 is advised both from the standpoint of economy and as a means of cultivating 

 the trees. Samples of rubber from the 2 and 3 year old trees submitted to com- 

 mercial firms compared favorably ns to value with prime Para rubber. 



The climatic and soil requirements of Hevea brasiliensis, A. Zimmermann 

 {Pflunzer, 5 {1009), No. 13-U, Pp. 205-211).— A discussion of the climatic and 

 soil requirements of Para rubber based upon data secured from rubber planta- 

 tions in various parts of the Tropics, to which a bibliography of rubber culture 

 is appended. 



The author concludes that Para rubber is adaptable to those regions in the 

 German colonies under 600 meters altitude, with a rainfall of about 2 meters, 

 no long continued dry spells, and fairly moist winds. The soil should be fairly 

 rich in humus. 



On the effect of arsenical and sulphur fumes on veg'etation, with par- 

 ticular reference to the Para rubber tree (Hevea brasiliensis) and Ram- 

 bong (Ficus elastica), B. J. Eaton (Afft: Bui. tStraits and Fed. Malay IStates, 

 f> (1910), No. 2, pp. Ji6-51).— In view of the supposed deleterious effect of the 

 fumes from the Chinese furnaces roasting low grade tin ores, a small furnace 

 was erected in the grounds of the Institute for Medical Research and actual 

 experiments conducted with a number of potted rubber plants. 



The results of the experiment proved conclusively the harmful effect of these 

 fumes. They do not show whether the injury is due to the arsenious acid or 

 to the sulphur dioxid in the fumes, but iu the author's opinion the latter was 

 the more hai-mful. " The first noticeable effect is a spotting of the leaves, 

 yellowish white spots being found on the surface, which gradually spread over 

 the whole surface of the leaves, the latter eventually dropping off. The plants 

 thus become quite defoliated. The leaves naturally grow again if the fumes 

 are stopped, but if the fumes from the furnaces are continuous, as is the case 

 in practice, then complete defoliation would occur, and the plant would 

 subsequently die." 



