ON THE ROLE OP SILICA IN THE WHEAT-PLANT. 347 



to have seen in Britain with that grown on this side of the world, 

 I think they will find a great diiierence, the latter being much 

 softer than the former." 



We fare little better when we come to investigate what is 

 known concerning the physical or chemical nature of the Darling 

 Downs soils. An analysis made in England by T. Hughes, F.C.8., 

 of a soil from Killarney, which the late Mr. R. Daintree described as 

 being " a fair average sample of the black soil " of the Darling 

 and Peak Downs, and of the Volcanic Districts of Queensland 

 generally," showed that this soil yielded on analysis 49.416 per 

 cent of insoluble, and 17.944 per cent, of silica .soluble in alkali, 

 or a total of 67.360 per cent, of silica.* 



Again from analysis made by Mr. K. T. Staiger, of nine 

 samples of what he designates " dark rich chocolate brown soil 



especially adapted for wheat-growing," and pro- 

 cured by this chemist from the northern Darling Downs, near 

 Jimbour, we find that they contain on an average 17.411 percent, 

 of silica soluble in alkalies, and 51.317 per cent of insoluble 

 residue, or a total of 68.728 of silica and clay.f 



According to an analysis made by Professor May, we find, on 

 calculation, that the amount of silica removed from the soil by 

 wheat, taking the average of twenty crops, was 80 per cent, of the 

 total quantity of material obtained by it from this source of 12 

 per cent, more than M. Gueymard (Vide p. 343) stated should be 

 the proper amount of this mineral present in the same cereal. 

 According to investigations of Professor Wilson, to which we have 

 alluded, the state of the division in which the silica exists in soils 

 when testing their capability of growing siliceous, and so perhaps 

 rust resisting wheat becomes a matter of great importance. As far 

 as we are aware no mechanical examination of Darling Downs 

 soils has been made, and in the absence of the information 

 derivable from such examination the mere chemical estimation of 

 its constituent elements becomes of subordinate importance only. 



11.— ON THE NEPHRIDIA OF EARTHWORMS. 



By W. Baldv.in Spencer, B.A., Professor of Biology in the 

 University of Melbourne. 



12.— ON SUCCESSFUL RABBIT-SUPPRESSION IN NEW 

 ZEALAND. 



By Coleman Phillips, of Wairarapa, New Zealand. 



•Analysis of Queensland Wheat and Sugar Soils, with Dr. Volcker's Report on their 

 fertility, 1874. p. 17. 



t Report to Queensland Investment and Land Mortgage Co. Limited, 28th April, 1887. 



