PHYSIOLOGY OF THE COCO-NUT 13 



ditions. Observations made by a different method, 

 which was calculated to show at each time the trans- 

 piration in full sunshine, gave figures from which the 

 calculated daily loss of water from the whole tree is 75 

 litres. If we use the lowest figure based on a full set 

 of observations, that is, 28 litres a day, the annual 

 transpiration would be 10,220 litres. 



In this water the plant takes up the mineral food 

 to be used in its permanent growth, and enough in 

 addition to cover the annual loss in the nuts and in 

 the leaves which are cast. The amount of mineral food 

 permanently bound up in the growth of the stem and 

 roots cannot be very considerable, and that in the roots 

 which die is already in a place where it can be absorbed 

 again. The average dry weight of a fallen leaf may be 

 put roughly at 3 kilograms, of which 8*5 per cent is 

 ash and nitrogen. Allowing a fall of sixteen leaves 

 per annum, the loss of matter taken up in solution by 

 the roots is 4080 grams. In each nut the tree loses 

 ash as follows : 



Grams. 



In the husk . . . 33 '84 

 In the shell . . . 3*36 

 In the copra . . . 13 - 83 

 In the milk . . . 5*97 



57-00 



If the tree produces but twenty nuts per annum, 

 the loss of mineral matter in these is 1140 grams, and 

 the total loss in leaves and nuts 5220 grams. If this 

 were absorbed in 10,220 litres of water, as already 

 calculated, the concentration of the solution taken up 

 by the roots would be 0*051 per cent. This is con- 

 siderably above the average concentration to be found 

 in ground water, as - determined by analyses of water 

 in wells and springs ; but the water which roots absorb 

 from any but the wettest soil, being in immediate 

 contact with the soil particles, is sure to be more 

 concentrated than that which would run freely from 



