Most of our knowledge concerning assimilation has been gained from observations and experiments on Dicotyledons. Sachs’ work on the rôle of starch in the leaf referred to such Dicotyledons as Helianthus , Phaseolus , and Cucurbita , which are great starch-formers. In Monocotyledons, however, it is the exception to find starch in the mesophyll -just the reverse of what occurs in Dicotyledons. Böhm noticed as far back as 1856 that there are certain Monocotyledons e. g ., Asphodelus luteus , Allium fistulosum ,and Orchis militaris , the chloroplasts of which are incapable of manufacturing starch, and A. Meyer in 1885 published his elaborate investigations on the occurrence of starch in various foliage leaves, and stated as a general conclusion that Dicotyledons store starch plentifully in their leaves, while Monocotyledons store little or none. He attempted to explain the absence of starch in these plants, and considered that it might be due to too rapid translocation of the assimilated products from the mesophyll as compared with the energy of assimilation. Experiments were made by exposing detached leaves to the most favourable conditions for assimilation, in order that the products might accumulate in the leaf, but the leaves of plants which did not form starch under ordinary circumstances also failed to do so here, with only two exceptions, viz., Hemerocallis flava and Muscari moschatum . He considered, therefore, that the temporary reserve in the leaf assumes some other form. Meyer also attempted to investigate the nature and amount of sugars in such Monocotyledons as well as in some Dicotyledons, and obtained results indicating the interesting fact that the leaves of plants which store starch abundantly, contain comparatively little of the reducing and non-reducing soluble carbohydrates, whilst those which form no starch, such as Iris germanica , Allium Cepa, Asphodelus luteus, &c., accumulate large quantities of soluble reducing substances, probably hexoses. The appearance and disappearance of these carbohydrates seem to depend on the same causes which regulate the appearance and disappearance of starch in other leaves. Another important discovery made by Meyer is the occurrence of a fructose-producing carbohydrate, which he termed Sinistrin, in the leaf of Yucca filamentosa , and which is probably an Inulin.