Then in dioecious and monoecious plants, both male and female flowers must be collected, and in some cases, as in the willows, four specimens are necessary to the complete presentment of the species, showing respectively the male and female catkins, the leaves, and the fruit. Some plants produce two distinct forms of blossom, as is noticeable in the violets and the woodsorrel, one being conspicuous and usually barren, the other insignificant and often apetalous, but producing perfect fruit. The pollen will afford occupation to the microscopist: the researches of Mr. Gulliver and Mr. Charles Bailey have demonstrated that important distinguishing characters are in some instances furnished by it. While on this point it may be suggested that it is convenient in many cases to collect several specimens of the flowers alone, which, when dried, should be placed in a small envelope or capsule, and attached to the sheet on which the plant is represented. In the event of any examination which may be requisite after the plant is dried, these detached blossoms will be found very useful, and will prevent the necessity of damaging the specimen. In the case of such plants as shed their corollas very readily, as the speedwells, it is as well to put them in press as soon as collected; and the colour of many may be retained by the same means. The fruits and seeds of plants are too generally neglected by amateur collectors, but are essential to the completeness of a specimen. It may be found practically convenient to keep these in a separate place, and detached from the plant; and in many cases of dried fruits it is advisable to sort them into their places without previous pressing. By this means the modes of dehiscence will readily be seen: pulpy and succulent fruits should be preserved in spirit. In such plants as the species of sea sandwort (_Lepigonum_), and some Chenopodia, important specific characters are drawn from the seed; as they are from the pods of _Melilotus_ and the fruits of _Agrimonia_. In collecting ferns, well-fruited fronds must be selected, as it is impossible to determine specimens without fructification. Grasses should be selected when in flower and fruit, but must not be allowed to attain too great an age before they are collected.