Fhosplionts. 375 



Eucilypfcus ainygdalina or "INIessmate " = 4.456 % 



Eucalyptus hemiphloia or " White Box " = 2.436 % 



Eucalyptus haemostonia or "White Gum" = 2.304 % 



Eucalyptus polyanthemus or "Red Box" = .856 % 



Of these four the messmate is a veiy quick-growing tree, and 



is amongst the highest trees of the world. The Red Box, on 



the other hand, is a slow growing tree, with very hard wood. 



This difference very likely accounts for the diversity of the 



P.2 O.. content of the stems of these two, for wherever active 



gi'owth is going on the P-jO., content is higher than in the 



inactive part, and the actively growing sap wood has always a 



higher percentage than the hard inactive heart wood. 



Czapek (10) gives the percentage of P.,0,-, in the ash of the 

 branch wood of Pinus Silvestris as 11.60; and the percentage 

 in the heart-wood of a beech 220 years old 4.54, and in the 

 sap-wood of the same 13.21 ; in the heart-wood of an oak 50 

 years old 5.88. and in the sap-wood 14.28 ; in the heart-wood 

 of Betula 16.59, and in the sap-wood 13.21. All of these figures 

 are higher than those obtained in the above analyses of the 

 four Australian types taken, which fact again seems to point 

 to an adaptation by plants to a phosphorus-low soil. 



A further indication of adaptation is given by Isopogon cera- 

 tophyllus, a sample of which was kindly supplied by Dr. Cherry. 

 This is a prickly shrub which only grows in poor soils, and on 

 analysis was found to have an exceedingly low phosphorus con- 

 tent, viz.: 0.033/,' in the dried substance of the woody stems, and 

 1.44/^ iu the ash of the .same ; and 0.046% in the dried substance 

 of the leaves, and 2.09% in tiie ash of the leaves. 



B. — ^Experiments with some Human Foods. 



The extraordinarily wide distribution of phosphorus in the 

 body — in bones, neiwous system, all the great gland organs, 

 etc. — makes it an essential ingredient of food. According to 

 Siven (1) the body needs at least .7 to .8 grams daily, and 

 according to Ehrstrom more than this, viz., 1 to 2 arrams 

 daily. Hart, McCollum and Fuller (12) fixed 3 grams of phos- 

 phorus per day as the safe minimal quantity for a pig of 50 

 lbs. weight. The body has a greater power of retaining this 



