Several species of Momordica, cultivated by us, like other Indian vegetables, in close stoves, have frequently borne female flowers; which, although at first very vigorous, after a short time have constantly faded and turned yellow, without perfecting any seed, till I instructed the gardener, as soon as he observed a female flower, to gather a male one, and place it above the female. By this contrivance we are so certain of obtaining fruit that we dare pledge ourselves to make any female flowers fertile that shall be fixed on. The _Jatropha urens_ has flowered every year in my hot-house; but the female flowers coming before the males, in a week’s time dropped their petals and faded before the latter were opened; from which cause no fruit has been produced, but the _germina_ themselves have fallen off. We have therefore never had any fruit of the Jatropha till the year 1752, when the male flowers were in vigour on a tall tree, at the same time that the females began to appear on a small Jatropha which was growing in a garden-pot. I placed this pot under the other tree, by which means the female flowers bore seeds, which grew on being sown. I have frequently amused myself with taking the male flowers from one plant, and scattering them over the female flowers of another, and have always found the seeds of the latter impregnated by it. Two years ago I placed a piece of paper under some of these male flowers and afterwards folded up the pollen which had fallen upon it, preserving it so folded up, if I remember right, four or six weeks, at the end of which time another branch of the same Jatropha was in flower. I then took the pollen, which I had so long preserved in paper, and strewed it over three female flowers, the only ones at that time expanded. The three females proved fruitful, while all the rest, which grew in the same bunch, fell off abortive. The interior petals of the _Ornithogalum_, commonly but improperly called _Canadense_, cohere so closely together that they only just admit the air to the germen and will scarcely permit the pollen of another flower to pass; this plant produced every day new flowers and fruit, the fructification never failing in any instance; I therefore, with the utmost care, extracted the antheræ from one of the flowers with a hooked needle, and as I hoped, this single flower proved barren. This experiment was repeated about a week after with the same success.