plant. It is an element vastly important in every department 

 of biology, since the nucleoproteins which constitute so large a 

 part of the nucleus of every living cell are rich in phosphorus, 

 and it is also an essential ingredient of lipoid, which recent 

 research has shown to be so important a component of all living 

 tissue. Lilienfeld and Monti discovered pliosphorus in bacteria, 

 and analyses of dry bacteria have shown the percentage of 

 PoO,; to be greater than that of any other ash constituent 

 (1). For example, in 100 parts of dry substance of Bacillus pro- 

 digiosus the total ash = 13.47, K,0 = 1.55, Na.p = 3.93, CaO 

 = .56, MgO = 1.05, PA = -^-l^, CI = .66, NaCl = 1.08, SiO, 

 := .07. In 1796 Westrumb demonstrated presence of phos- 

 phoric acid in the beer yeast, almost half of the pure ash 

 being phosphoric acid. Yeast placed in a sugar solution bereft 

 of all salts can not bring forth fermentation to any appreciable 

 degree. Mayer placed phosphoric acid in the list of the salts 

 necessary for growth of the yeast jjlant. 



It is a significant fact that all tissues provided for the main- 

 tenance of the young are rich in phosphorus. Thus not only 

 eggs and milk, but plant seeds, are rich in this constituent, the 

 percentage of P.jO.- in the ash of ripe seeds is seldom below 

 25, and may reach 50 (2). [See analyses of Wolff, Kellner, 

 Lehmann, Presse and Stansell, etc.] Where the phosphorus 

 poor tegument is included in the analysis the results are of 

 course lower. Most of the phosphorus in seeds is in organic 

 combination, such as glycerophosplioric acid or pliytovitellinin. 

 The phosphoric acid content in the ash of the underground 

 food reservoirs of the plant is usually markedly lower than in 

 seeds, viz., about 15 per cent., but is very variable. The supply 

 of phosphoric acid has a noteworthy effect on the storing of 

 sugar in storage roots, a rich supply of phosphoric acid causing 

 an increased sugar content in the root (3). Also in the wood 

 of trees, in the sap wood more than in the heartwood, and 

 more in the upper actively growing parts of the tree than in 

 the lower parts ; in the bark and in the leaves we find phos- 

 phoric acid, in various kinds of combination, as a necessaiy 

 constituent. 



Of essentially animal tissues it forms, in combination with 

 calcium and magnesium, as phosphate, some 85 per cent, of the 



10 



