Vol. Xm. No. 317. 



THE AGRICULTURAL NEWS. 



19.5 



opposing factor of desiccation is a progressive one: but 

 the best results of all are produced by a combination 

 aiming at the conservation of moisture, together with 

 the production of plants which make the lowest 

 demands upon this water-supply whilst giving 

 a maximum yield of high quality produce. 



THE RELATION BETWEEN RAINFALL 

 AND VEGETATIVE REST. 



Ill tempt late regions it is well known that prriods of 

 vegetative rest occur as a whole, and are largely due to the 

 effect of the low temperature which prevails during winter 

 time. In the Tropics seasonal cbange.s which occur, prin- 

 cipally in connexion with alternations of drought and rainfall, 

 render periodic variation less obvious, and induce resting 

 periods only for certain functions rather than periods of 

 rest for vital processe.s as a whole, though a dry sea.son in 

 a measure has a similar effect to the winter temperatures of 

 a cold country. In a nearly uniform climate like that of 

 the West Indies internal causes are mainly or solely respon- 

 sible for the alternation of rest and of activitj . 



The truth of this circumstance has recently been very 

 clearly shown in Barbados during the long prevailing 

 drought which h;i8 characterized the climatic conditions this 

 year. The behaviour of most of the chaiacteriatic trees has 

 afforded interesting evidence of the remarkable independence 

 of rain to the coming into leaf and flower of the plants in 

 question. 



The rainfall in the neighbourhocd of Bridgetown 

 during the first five months of the year has been only 

 about 5 inches; but still the Frangipani trees have come 

 into flower in May in full profusion without any evidence of 

 being retarded or the flowers being sparse for lack of 

 moistwre. Similarly the Mahogany trees have shed their 

 old leaves and put out new ones with, apparently, no inter- 

 ruption on account of the drought. 



The Flamboyant trees, which form a striking feature of 

 Bridgetown and its suburbs, are flowerint; profusely early in 

 June and under conditions where it does not appear that 

 the roots of the trees can be receiving any appreciable 

 supply of water. 



These remarks are general, but they are supported 

 by many observations of particular instances. For example, 

 the Mahogany trees in the grounds of Government 

 House, and young trees of the same species in the 

 gardens of neighbouring houses on the Pine Hill, sit- 

 uated in positions where the soil is shallow and where 

 no water appears to reach the roots, have gone 

 through- the usual leaf-fall and renewal. Note has been 

 made of a clammy cherry tree (Cordia coUoi'rn) on the 

 Pine pasture a few yards from the entrance to Bishop's 

 Court; this tree is growing on a ridge of hard coral rock in 

 extremely scanty .soil: to the eastward there is a cleft or 

 gully about 15 feet deep, effectively preventing access of 

 water from that side; while on the other side there is a dry 

 fragment of pasture with the coral rock showing through at 

 very frequent intervals, and no evidence of any water supply. 

 "N et this tree is now in full leaf and flower and young 

 fruit. 



Instances of this kind could be multiplied indefinitely, 

 but the most striking instance of the seasonal flowering of 

 a tree independently of rainfall or other surrounding con- 

 ditions is exemplified by a case recently reported. A branch 



having three bud ends was cut from a Frangipani tree in 

 February and fell over a wall on to a dry rock under 

 a Terminalia CoAappa in such a position as to be effectively 

 protected from any rain, though very little fell: the situation 

 is such that the rock falls away rapidly and there is no 

 indication of surface water having reached the severed branch. 



At the beginning of June, it was observed that the 

 branch was blossoming freely, one end having fully devel- 

 oped flowers and the others two prominent bud clusters. 

 On all three ends the leaves had started to develop. At this 

 time the parent tree is approaching full bloom. 



It is interesting to note that the cut end of the branch 

 is dry and shrunken, showing no evidence of having received 

 moisture. It was noticed that the whole structure was some- 

 what shrunken with the exception of the upper 6 or 8 inches 

 of each one of the ends. 



This affords a striking illustration of the fact that 

 seasonal flowering is due to internal causes and is independ- 

 ent of external stimulus. 



SUGAR INDUSTRY. 



SYRUP TREATMENT. 



In the manufacture of white sugar it is very essential 

 to have the syrup which is taken into the pan as clear and 

 free from suspended particles as possible. A clarified juice, 

 cirried slightly acid, which has been very caiefuUy filtered 

 before evaporation, will give a syrup which is very fairly 

 free from su.«pended impurities. This is a generally recog- 

 nized fact in Louisiana, and our experiments have confirmed 

 the view. It is therefore extremely desirable to make the 

 clarification and filtration of the juice as perfect as possible, 

 especially if the facilities of the factory do not allow of 

 adequate treatment and manipulation of the syrup. 



In houses where the whole juice is not filtered at least 

 once, the syrup is likely to be fairly clouded with suspended 

 matter, at least now and then, and this will undoubtedly be 

 detrimental to the quality of the sugar obtained. It would 

 appear, therefore, that in the endeavour to turn out the 

 highest grades of sugar the removal of mechanical impurities 

 from the syrup would be essential where juice filtration is 

 not carried out, and often beneficial where this practice 

 obtains. 



A series of experiments was planned to determine how best 

 to remove the suspended matter in syrups. Sjrups from juices 

 clarified by double carbonatation or a thorough single carbonat- 

 ation were found to filter well through bags or other mechanical 

 filters. Sulphitation juices, on the other hand, yielded 

 syrups which, while more in need of filtration than those 

 from carbonatation, it was not possible to filter successfully. 

 Settling had therefore to be resorted to. Experiments 

 showed that even this operation was very difficult if the 

 syrup was more concentrated than about 26" Beaumc. It 

 was, moreover, easier to settle the syrups the higher 

 the temperature to which thej' were heated before settling. 

 In our experiments the syrups were heated to at least 

 70°C., and suitably .small portions of various settling agents 

 added, allowing the syrup to settle during a limited time. 

 The results indirated that most success was obtained with 

 common sodium phosphate, using 1 or 2 parts (dissolved Ie 

 a small quantity of water) to 100,000 of syrup. The syrup 

 thus treated settled well, usually within three or four hours. 

 The scums were mixed in with the raw juice, thi-. being 

 found to be the best way of disposing of them. (Fiom 

 Louisiana Agricultural Experiment Statiov Bulletin, 

 No. 14 4.) . . 



