Neither Risso, in his excellent monograph of _Citrus_, nor modern authors, as Brandis and Sir Joseph Hooker, have been able to discover any other character than the taste to distinguish the sweet orange from more or less bitter fruits. This difference appeared to me of such slight importance from the botanical point of view, when I studied the question of origin in 1855, that I was inclined, with Risso, to consider these two sorts of orange as simple varieties. Modern Anglo-Indian authors do the same. They add a third variety, which they call _Bergamia_, for the bergamot orange, of which the flower is smaller, and the fruit spherical or pyriform, and smaller than the common orange, aromatic and slightly acid. This last form has not been found wild, and appears to me to be rather a product of cultivation. It is often asked whether the seeds of sweet oranges yield sweet oranges, and of bitter, bitter oranges. It matters little from the point of view of the distinction into species or varieties, for we know that both in the animal and vegetable kingdoms all characters are more or less hereditary, that certain varieties are habitually so, to such a degree that they should be called races, and that the distinction into species must consequently be founded upon other considerations, such as the absence of intermediate forms, or the failure of crossed fertilization to produce fertile hybrids. However, the question is not devoid of interest in the present case, and I must answer that experiments have given results which are at times contradictory. Gallesio, an excellent observer, expresses himself as follows:—“I have during a long series of years sown pips of sweet oranges, taken sometimes from the natural tree, sometimes from oranges grafted on bitter orange trees or lemon trees. The result has always been trees bearing sweet fruit; and the same has been observed for more than sixty years by all the gardeners of Finale. There is no instance of a bitter orange tree from seed of sweet oranges, nor of a sweet orange tree from the seed of bitter oranges.... In 1709, the orange trees of Finale having been killed by frost, the practice of raising sweet orange trees from seed was introduced, and every one of these plants produced the sweet-juiced fruit.”[897]