Collecting is an important means of ecological study. This is particularly true in the early stages of such study, but as the student becomes familiar with species and comes to know many of them at sight, less collecting will be necessary, except in the case of very small species and in those studies which depend upon the total catch as a means of securing data, as, for example, the case of plankton organisms. On account of the large number of species, very few students will be able to determine them at sight, but this does not disqualify a student for beginning ecological study. The greatest aid in handling such a varied population is a numbering of the individuals, or lots of specimens, consecutively and recording the full data for them in the notebook. The question arises at once as to how many specimens are to be assigned to _one_ number. No rigid rule can be followed, but in general it is safe to assign a single number to all specimens which agree in _all the fundamental data_, as date, place of capture, and exact habitat. And for my own part I number all individuals taken, upon which any special observations are made, as when a Phymatid is taken with a dying or dead honeybee, or a dragon fly is taken from the web of an _Argiope_. In this way the confusion which is particularly liable to creep into one’s work, where he deals with a large number of species, and before familiarity with them is acquired, may be reduced to the minimum. For small animals I have found useful a very liberal use of vials, into which field numbers, corresponding to numbers in the field notes, are placed _immediately upon capture_ of the specimens, and not minutes or hours later when the vials have become mixed, and recollection is less sharp. Specimens which have been thoroughly numbered may thus be sent to specialists for determination. This method uses up many numbers, but, fortunately, the supply is unlimited, and it gives greater precision to one’s notes, and encourages detailed observations on individual animals. In the eyes of many the determination of specimens is such a formidable task that they are at once repelled from any subject which involves numerous species. But as we have previously remarked, there are phases of ecological study which involve only a minimum amount of such work. On the other hand, one may readily have an undue fear of numerous species, but no one can doubt that the smaller number of species found upon mountains or in the far north gives to a beginner certain advantages for study. But if one’s studies are confined to the more restricted habitats, the number of species involved is comparable to the more favored localities mentioned.