350 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
fertility produced by those manures is soon shown by the appearance of 
the tree, whose briUiant dark green foliage raises great hopes. 
The nitrogen of the sulphate of ammonia excites the movement of 
the sap and directs its action to the green organs of the plant, producing 
the growth of the wood and foliage. But at the same time that this 
nitrogen is absorbed there is also absorbed, although more slowly, the 
phosphoric acid of the superphosphate, and this phosphoric acid is con- 
centrated in the vessels which afterwards produce the flower buds. 
Phosphorus attracts nitrogen ; therefore the phosphoric components of 
the plant tend to unite with nitrogenous components, and in this way 
nitrogen, which naturally prefers to remain in the leaf organs, passes on 
to the flower buds, contributing in union with phosphorus to nourish 
the incipient organs. Potash gives consistency to these organs and 
regulates, like phosphorus, the process of their formation. 
After the absorption of these elements of fertility there is in the 
interior of the plant, movement, work and effort, which cause a kind of 
collapse, a failing of the organic functions, in the same way that animals 
suffer from a prostration of the vital forces after a nervous crisis or the 
excessive use of any particular organ. What contributes to this faintness 
of the plant is the fact that the nitrogen, invited by the phosphorus, 
abandons its position in the green organs and goes to the floral vessels to 
assist with the other elements of fertility in giving splendour to the 
feast of flowers. The sweet caresses of the sun announce the spring- 
time, and the tree prepares to honour nature with its offering of flowers 
and scent ; an offering which, though repeated yearly, always appears new, 
always varied, and always grand. Amongst the foliage, with its depth of 
different shades of green, appear white garlands and little branches of 
Orange blossom, which, bursting with pride, show the golden stamens 
imprisoned within them. To the feast of flowers succeeds that of love ; 
the Orange blossom celebrates its nuptials caressed by the ardent and 
voluptuous kisses of the spring sun. The sexes assert themselves and 
fecundation takes place ; the plant has fulfilled Nature's law for the 
reproduction of the species. 
When manures are applied in the proper proportion and at the time 
mentioned, first the flowering, then the fecundation of the flowers, and 
lastly their fructification, all take place under healthy conditions, and the 
tree produces an excellent crop. In the contrary case there is much risk 
of losing the crop. If the fertiliser is applied later than I have mentioned 
its effects coincide with the flowering, the sap rises with hasty and 
impetuous ardour, the generating organs obtain an unequal or dis- 
proportionate growth, and the fecundation is bad or else non-effective. 
Consequently the flowers prove abortive. 
There is still another point. The minute grains of pollen are formed 
of two cells : one of them fecundises the nucleus of the embryonic sac and 
produces the embryo or germ of the seed ; the other cell, heavily charged 
with phosphorus, fecundises the matter surrounding the egg and gives 
birth to the albumen, the food which is provided for the use of the embryo. 
One cell therefore nourishes itself at the expense of the other. If the 
tree has not before flowering absorbed sufficient phosphates, of the two 
twin cells of the pollen grain, one will keep its power of fecundity, but 
