264 THE GREAT BARRIER REEF. 



for the adhesion of the spat. Such collectors are consequently well adapted for employment on 

 mud flats, where there is much sedimentary deposit, and under conditions in which other forms 

 of collectors would be useless. 



The " split-paling " collectors, first introduced by the author in the colony of Tasmania, as 

 the nearest approximate substitute for tiles, have, as explained in a previous paragraph, proved in 

 all ways equal to the latter as spat collectors ; and in various other directions they possess distinct 

 advantages. Their price of los. per i,ooo renders them cheaper for the purpose than any article 

 previously emploj^ed. With attached wire handles, they are more convenient for handling on the 

 exposed banks, and can, in addition, be easily deposited in or raised from water of a fathom's 

 depth. Their individually larger superficial area entails a considerable saving of labour in their 

 manipulation; while, as indicted on a preceding page, the circumstance of the cemented surface 

 being raised by the attached bricks or stones some few inches off the ground, secures to the 

 young oysters an immunity from the attacks of crabs, whelks, star-fishes, and other enemies, to 

 which they are exposed when the cemented surface, as in the case of tiles, is in immediate contact 

 with the sea bottom. 



The " split-paling " type of spat collector has, in fact, after an experiencce of its successful 

 application under a variety of conditions, proved to be the most convenient and economic form to 

 employ in Australian waters, and it may be characterised as an essentially Australian implement. 

 Sawn boards may, as a matter of course, be fashioned into collectors of identical form and effi- 

 ciency, but at many times their cost — the relative price of the respective materials averaging 20 

 feet for id. for the split palings, and i\A. per foot for the sawn wood. In practical use, the split 

 palings are further found to possess an advantage over the sawn material, as the roughly parted 

 natural grain of the wood furnishes a more favourable base for the attachment of the cement. 

 When split to order, for this purpose, they should average at least an inch in thickness, and 

 have as rough a surface as it is possible to obtain. Where split palings are not procurable, 

 rough discarded rails or boarding of any description, such as are usually abundant around every 

 settlement, may be pressed into service and be made to do good duty, before final condemnation 

 as firewood. In the preparation of these collectors, the palings or boards should be soaked for a 

 day or so in water, in order that the grain may swell to its full extent before the application of 

 the cement. Should this precaution be neglected, the cement will not adhere to the wood. Salt 

 water is as good as fresh for mixing the cement, and, as the process may be most conveniently 

 performed at the water's edge, in the immediate neighbourhood of the beds under cultivation, this 

 proves a distinct advantage. From experience gained by the use of these collectors in Queens- 

 land waters, it may be observed that about half-tide mark represents the zone within which the 

 most abundant harvest of spat can be gathered, and this at all times of the year, though the 

 months of February and August are more especially propitious for the purpose. 



On their first attachment to the cemented collectors, it will be found that the young oysters 



