370 Hihhi, Kiiicaid: 



bone ash. In muscle the predouiinatinji' salt is i)t)tassiiim phos- 

 phate, the percentage of P/l, in the ash being- roughly 35. 

 Brain and nervous tissue are rich in P./'.,, the ash containing 

 nearly 35 per cent. In lungs and bronchi again the predomi- 

 nating constituent of the ash is pliosphoric acid, obtained for 

 the most part from organic combinations (4). The Liver, Spleen, 

 Thymus, also, being rich in cellular elements, have a high per- 

 centage of phosplu)rus in organic combination. 



From the time of Liebig attention has been centred on nitro- 

 gen as the food element of living things most liable to fluctua- 

 tion or deficiency; but it must be remembered that nitrogen 

 is in reality air-borne, and an increased demand for this element 

 can be met by increasing the facilities for trapping the air 

 nitrogen. With phosphorus, however, the case is different. It 

 is a constituent of soil or is water-borne, and may be described 

 as the one element about which plants are conservatiA'e. Thus 

 it has been shown that the leaves of deciduous trees before 

 being allowed to fall from the j^lant have practically all the 

 pliosphorus extracted from them (5). In much the same way 

 we find animials to be conservative of this element, so that in 

 the young animal where much phosphorus is needed for the 

 growing skeleton the amount excreted is very low. Tiie same 

 is the case during the processes of dentition and lactation. 



The widespread distribution of this element in all living 

 things makes it desirable that there should be in soils a large 

 quantity available to plants. That soils may contain a low 

 percentage of available phosphorus is unfortunately well exem- 

 plified in many regions of Australia. This lack of pliosi)horus 

 has been generally recognised for some time, and is indirectly 

 proved by the excellent results following the use of phos- 

 phatic fertilisers. Analyses by agricultural experts in the State 

 of Victoria may be found in the Agricultural Journal of Victoria, 

 1907, comparing the Victorian clay soils with American clay 

 soils. The clay soils are given because they contain a higher 

 percentage of phosphorus than other soils. Thus giving the 

 pliosphorus in terms of phosphoric acid, in 100,000 parts of 

 Victorian clay soil we find only 63 parts of phosphoric acid of 

 against 207 parts of phosphoric acid in the same amount of 

 American clay soil. The difference in the sub-soils is not quite 



