An animal or a plant must be studied from several points of view before its manner of life can be understood in any real sense. It must, for example, be regarded, first, as a complicated piece of machinery, every part of which is beautifully fitted for the performance of a special duty; it must also be considered as an individual, having likes or dislikes—or at least tendencies—which are to some extent peculiar to itself; finally, it must be considered in its relation to other animals and plants, and to its surroundings. Field-work is especially concerned with the last of these methods of study—the observation of living things under natural conditions,—and this ought constantly to be borne in mind. To make nature-study a pretext for uprooting locally-rare plants and robbing birds’ nests is indefensible. The commonest plants are usually the most instructive, and afford ample material for the beginner’s experimental work; while the pleasure of finding and describing (perhaps photographing) a bird’s nest, and of keeping the eggs and young under observation, is something unknown to the mere collector of eggs. The life of both plant and animal is sacred in the eyes of every nature-student worthy of the name. At the same time, no [Pg 389] sentimentality ought to prevent the destruction of undoubtedly noxious insects and weeds. In general, however, specimens should be killed only for the purpose of a leisurely examination of structure, which would otherwise be impossible, or to make needed additions to the teaching-collection of a school museum. Generally speaking, collecting is of very doubtful value, except to experts. Insects and common plants may, however, be collected without scruple by the beginner, though it is worth remembering that the most perfect specimens of butterflies and moths are those reared in captivity from the eggs, larvae, or pupae.