Passerini (1891) found traces of boron in the stems of chickpea plants, while in 1892 Brand determined boric acid in the ash of beer. In consequence of this various samples of hops were ashed without the addition of any alkali, and then the ash was distilled with sulphuric acid and methyl alcohol. When tested all the hops showed relatively large quantities of boric acid in comparison with beer, hence he argued that the boric acid in beer is derived from the hops. Boron was discovered in various parts of the hop plant--in the clusters, leaves, pedicels, and stems. Jay (1895) analysed many plants and plant products grown in various soils and waters, and arrived at the conclusion that boron is of practically universal occurrence in the plant world. Of all vegetable liquids wines are the richest in this constituent, the amount varying from ·009 gram to ·33 gram per litre. He confirmed Hotter’s statement as to the richness of fruits in this substance, finding from 1·50–6·40 grams in 1 kgm. of ash. Chrysanthemums and onions, amongst other plants, are well off in this respect, containing 2·10–4·60 grams per kgm. of ash. Jay also found that the plants vary in their capacity for absorbing boric acid, those which do so the least easily being Gramineae (as wheat, barley, rice), mushrooms and watercress, the quantity in these plants never exceeding ·500 grams per kgm. of ash. Of all the workers upon boron, Agulhon has done the most to extend and concentrate our knowledge of the subject. He used the most refined, up-to-date methods for the detection and estimation of boric acid, and so determined its presence in many plants, including angiosperms, gymnosperms, ferns, algae, and fungi. Tobacco is so rich in boron that it can be detected in the ash of one cigarette. Among the plants tested, the highest percentages of boric acid were found in _Betula alba_ (1·175% of ash) and _Laminaria saccharina_ (·682% of ash), the lowest in _Cannabis sativa_ (·123% of ash). Generally speaking annual plants and parts of plants seem to have the least boron in the composition of their ashes. In one and the same plant the durable parts like bark and wood are richer than the leaves, even in evergreen trees. He indicated that plants seem to have a great affinity for boron, as even when plants are grown on soils in which the boron is practically indetectable they always seem to extract an appreciable quantity of the element.