184 I-ERTILISERS FROM THE OCEAN. 



7. Rytiplductt Pinastroides. — In the Atlantic Ocean. 



8. Fiicus Crispus. — Throughout the Atlantic. 



He gives* some interesting- analyses : — 



Water. Nitrogen Ash. 



Fucus Vesiciilosiis 7^-57 3- 5-37 



Fucus Nodostis 74-3i 28 4-89 



Laminaria Digitata 88. 6g 15 5.46 



Furcellaria Fastigiata 80.44 45 10-31 



The ashes of these sea plants contained : — • 



Li Mi:. Potash. Oxide. 



Phosphoric 



Fucus Vesiculosus 8.92 -o-75 2.14 



Fucus Nodosus 9.60 20.03 ^•7'' 



Lamiriaria Digitata 7.21 5.55 2.42 



Furcellaria Fastigiata ... 7-7-\ 20.24 1.72 



The author adds ; — 



"These analyses prove that the manurial value of these plants is very con- 

 siderable. They are distinguished by the large amount of Potassic Oxide and 

 Nitrogen, whilst the quantity of Phosphoric O.xide is somewhat low, for this 

 reason it is advisable to use broken bone or bone-meal together with the sea-weed 

 in order to supply the soil with these three essential constituents of plant food in 

 the proper proportion." 



All plants require as plant food the following- substances : — 

 Sulphuric Oxide. Carjjon Dioxide. IMag-nesic Oxide. 



Phosphoric Oxide. Water. Calcic Oxide. 



Nitrogen. Potassic Oxide. Ferric Oxide. 



Of these, Phosphoric Oxide, Nitrogen and Potassic Oxide are 

 not present in sufficient quantity in the soil, and must therefore be 

 supplied as manure. For the coast districts of the Western Pro- 

 vince the quantity of Lime is of special importance, as the soil is 

 singularly deficient in this essential constituent. It may not be 

 amiss here to enumerate briefly the more important functions that 

 these important constituents perform in plant life. 



Phosphoric Oxide. — This constituent is found in all soils, 

 and a soil is said to be rich in Phosphoric Oxide if it contains as 

 little as . I per cent. From the lowest to the highest class of plants 

 all contain Phosphoric Oxide. It participates in the formation of 

 albuminoids, and as these are formed in the young leaf it is 

 evident that the young leaf contains more Phosphoric Oxide than 

 the old leaf, and hence requires when young a source of this con- 

 stituent to draw upon. At a later stage the Phosphoric Oxide 

 passes from the leaves to the stem and seed of the plants and is 

 replaced in the leaves by Silica. This explains the fact that seeds 

 of plants are richer in Phosphoric Oxide than any other part. 

 Phosphoric Oxide has a distinct ripening effect, and besides this 

 it stimulates the development of seedlings in young plants. As 

 an example of the amount of Phosphoric Oxide required hx plants 

 \ e give the following : — 

 From 1 acre of land Wheat takes in the seed and straw 21 lbs. 



of Phosphoric Oxide. 

 From I acre of land Potatoes take in the seed and straw 29 lbs. 

 of Phosphoric Oxide. 



* Op. cit., page 417. 



