Tot. XII. Xo. 284. 



THE AGRICULTURAL NEWS. 



91 



apple. This insect differs from the lime twig borer in the 

 important particular of the manner in which the twig is 

 girdled. 



The egg is laid in a small Kranch, as is that of the lime 

 twig liorer. The young larva eats out thi^ small branch, and 

 soon after entering the larger one, girdles it in sivh a manner 

 that it breaks otf and falls to the ground,. The larva is in the 

 fallen portion: this coming in contact \vlth the moist condi- 

 tions on the ground begins to decay and the larva feeds on 

 decaying wood tissue. 



In a recent number of the Ayriculfural yew.< (see Vol. 

 XI, p. '2-50) an account was given of the twig girdlers of the 

 genus Oiicideres, 0. umputatjr being the West Indian form. 

 In the case of these insects, the girdling of the twig is accom- 

 plished by the parent female beetle in such a way that the 

 portion in which the egg is laid will fall to the ground, and 

 the larva in this case feeds from the beginning of its life on 

 dead and decaying vroody tissue. 



The lime tree bark borer (LeptoUijlus praemorsns) 

 ditfers from the lime twig borer in habit and manner of 

 attack. The twig borer, as already explained, attacks the 

 Swigs and branches of the lime, whilst the bark borer begins 

 its attack in patches of dead bark on the main stem of the 

 tree which are often occasioned by wounds from implements 

 ysed in tillage, or by bad pruning. The larvae feeding at the 

 junction of dead and living tissue hastens the death of the 

 bark and soft sap wood, and, when the attacks are suffi- 

 ciently severe, the entire tree is sometimes killed from 

 a point near the level of the ground. 



TBE nature; of cacao 



FERMENTATION. 



Recently communicated to the Chemical Society and 

 published in their journal for Xovember 1912, is an important 

 paper by Bainbridge and Davies (of Messrs. Rowntree it Co., 

 Ltd.) entitled The Essential Oil of Cocoa. 



Much of the information it contains is purely of scientific 

 interest, but those matters dealt with, which are likely to 

 prove useful and interesting to the cacao grower have been 

 abstracted as follows. 



The essential oil was obtained in the investigation by the 

 distillation of cacao nibs. It possesses an intense odour of 

 cacao, and the flavour was clearly perceptible in a dilution of 

 1 in 50 million parts of dilute syrup. The flavour is most 

 nearly akin to that of coriander oil. It is pointed out that 

 • in the method of preparing cacao beans in the Tropics by 

 fermentation and slow drying, a number of possible ethereal 

 substances are added naturally to the crude oil. To explain 

 this,adescription is given of the different fermentation changes, 

 as investigated by one of the authors in the West Indies 



The first runnings from the fermenting box contain 

 alcohol, invert sugar and tartaric acid. Part of this liquor 

 penetrates into the beans, but the shell membrane is fine 

 enough to prevent the microorganism*, which lead to the pro- 

 duction of these substances, from percolating to the kernels. 



During the first twenty-four hours of fermentation the 

 temperature rises to 3.5°(J. or 40'C., varying with the exact 

 position of the box. Within forty-eight hours it rises to 

 40°C. to 45°C., and if the fermentation is continued for five 

 or six days, the temperature will be found to rise to 

 a maximum of 4-^ C. to -50 C. Higher temperatures are 

 occasionally noted when the fermentation is continued for 

 an exceptionally long period, for instance, ten to eleven days, 

 as in Trinidad. In this case, however, the temperature will 

 'fall towards the close. 



The biochemical nature of the different changes i* 

 explained as follows: — 



(1) A large growth of Sacckaromt/cefei apiculafua ('yeast') 

 together with small quantities of S. anonialus, doubtless 

 derived from the surface of the pod husks. This stage lasts 

 about twelve hours. 



(2) As in .spontaneous wine fermentation, an enormous 

 development of true Sac<:/tarovi;/cc/(fK occurs. If the tempera- 

 ture rises there will be no formation of new cells after tha 

 first forty-eight hours. The alcohol produced soon arresti 

 the growth of .*?. apirulatus and the 'wild' yeasts. A quantity 

 of alcoholic liquor drains away. 



(3) Acetic acid fermentation occurs. This is caused by 

 Bacillus accli brought in great numbers by swarms of tha 

 'vinegar fly' (Drosophila). If the temperature does not risa 

 above .50° C, the acetic bicteria continue to grow during 

 the remainder of the fermentation. 



(4) Finally, if the fermentation is prolonged beyond 

 eight days a growth of spore-bearing bacilli of the Bacillui 

 subtilis type will take place. 



In continuation the authors state: 'It is obvious that 

 a number of the products resulting from these complex fer- 

 mentations will percolate into the bean, and of these the lesa 

 volatile constituents will remain on the dry kernel. Conse- 

 quently we shall e.xpect to find that the true essential oil of 

 cocoa is accompanied by a certain number of esters and higher- 

 alcohols, analogous to those produced in other spontaneous 

 fruit fermentations taking place at comparatively high tem- 

 peratures in presence of a free supply of air.' 



After describing the chemical and physical properties of 

 the essential oil and other volatile products of cacao, the paper 

 concludes with a summary, part of which i.s reproduced >is 

 follows: — 



'(1) The aromatic principle of the cocoa bean is aa 

 essential oil. (2) Two thousand kilos, of cocoa nibs (deprived 

 of some cocoa butter) gave a yield of 24cc: of purified oil 

 with a very powerful aroma and flavour of cocoa. (3) The 

 oil was fractionally distilled three times and the third distil- 

 lation yielded seven fractions. (4) The early fractions were 

 rich in esters, derived in all probability from the fermentation 

 of the cocoa bean. (5) The middle fractions were rich ia 

 rf-linalool, corresponding closely with coriandrol. The tota! 

 linalool represents more than .^0 per cent, of the cocoa oil.'" 



Co-operation in St. 'Vincent: Report on tha- 



Agricultural Bank. — A copy <jf the Annual Report of thi 

 Board of Directors of the St Vincent .\gricultural Credit anil 

 Loan Bank, Ltd., has lately been received from His Honoilr thi* 

 Administrator of St. Vincent. The Company is incorporated 

 under the Companies Act and appears to be in a very 

 Hourishing condition. Owing to demands from shareholders 

 for loans, the management deemed it expedient to borrow 

 •f 400. Notice of this was given in the local papers in th* 

 month of May. The amount was immediately suliscribed an 1 

 on December 31, ><200 of the amount had been repaid. 

 Aa an outcome of the support of His Honour the Adminis- 

 trator and of the Imperial Commissioner of Agriculture^ 

 a further loan of .*!960 was obtained from the Britislk. 

 Cotton Growing Association for five years at 3 per cent, 

 per annum. The balance sheet for the past year shows new- 

 creditors, and records general progress. The bank's accounts, 

 by the courtesy of the < Jovernment, have been examined by 

 the Official Accountant. After making provision tor trans- 

 ferring $200 to the reserve fund, the lloard have reconi^ 

 mended that a dividend of 6 per cent, be declared on tha 

 inve.sted shares. 



