The great aim to be kept in view in collecting is to obtain as perfect and comprehensive a specimen as possible; that is, one showing every part of the plant--root, leaves, flowers, and fruit. It is not always practicable to show all these upon one specimen, and in such cases such a number must be selected as will carry out this plan. The wretched scraps with which some collectors content themselves are not only useless to their owners, but annoyances to everyone who has to do with them, or who is requested to pronounce an opinion upon them. Anyone who has had anything to do with naming plants for 'Science Gossip' or any other journal, which in this manner supplies information to its subscribers, will be able to testify to the large number of persons who do not scruple to send for determination single leaves, or a terminal shoot of a flowering plant, or a pinnule of a fern without fruit; a proceeding which is unfair to those to whom they are submitted, inasmuch as they either have to risk their reputation for accuracy, or to appear uncourteous by refusing to have anything to do with such specimens. [Illustration: Fig. 32. Lime (_Tilia Europæa_).] [Illustration: Fig. 33. Beech (_Fagus sylvatica_).] [Illustration: Fig. 34. Sycamore (_Acer pseudo-platanus_), showing cotyledons and first and second pair of leaves.] To begin at the beginning, How rarely do we find the embryo of any species represented in a collection of dried plants? It ought to be there, not only as essential to the complete presentment of the history of the species, but as in certain cases indicating relationships which are not apparent when the plant is more advanced. Those who have not observed them would be surprised to find how much variety of form exists in the cotyledons alone, from the fleshy cotyledons of many of the Leguminosæ, the horse-chestnut, &c., to the foliaceous ones, or seed-leaves, of other plants. Among the latter may be noted and compared the lobed or palmate cotyledons of the lime (Fig. 32); the glossy dark green, somewhat kidney-shaped ones of the beech (Fig. 33); and the pinnatifid ones of the common garden cress (_Lepidium sativum_); the obcordate ones of the mustard or radish; the long, narrow, thin ones of the sycamore (Fig. 34); the sinuous or corrugated and bilobed ones of the walnut, and many more which will occur to the observant reader, or which may be collected by anyone who will take the trouble to watch the germination of plants. And by making such collections, unexpected discoveries may arise, which will yet further confirm what has been said about the variety in form and structure even in these beginnings of growth. Plants which are, on account of their general affinities, reckoned among the dicotyledons, may be found on investigation to have but one cotyledon, as Dr. Dickson observed to be the case with two of our butterworts, _Pinguicula vulgaris_ and _P. grandiflora_, the third species, _P. lusitanica_, being