6. The limbs.—How many limbs has the rabbit? Which pair is the longer? Is the difference in length an assistance in leaping? Make out the main divisions of each limb, and, by feeling through the skin, the manner of attachment of its bones to the bones of the body (Fig. 161). 7. The tail.—Notice the length, shape, position, and colour of the tail. The chain of bones inside it is a prolongation of the spine. Methods of studying animals.—In studying animals, methods [Pg 214] similar in principle to those described in previous chapters for plants should be employed. A real knowledge of the habits of animals can only be obtained by watching them as closely as possible in their natural surroundings. It is often very difficult to get sufficiently close to shy animals to see them distinctly without causing alarm, and a good field-glass is a valuable help in such cases. A great deal of first-hand knowledge of wild life can, however, be gained without such aids if the student will learn to move quietly and silently, and to remain motionless as soon as he is in a good position for observation. The books of such masters of woodcraft as Richard Jefferies, William J. Long, Ernest Thompson Seton, and W. H. Hudson give charming descriptions of the methods of tracking and studying wild animals, and should be carefully read by every field-naturalist. Observations made in the field should be at once recorded, with the date, in a note book. Many animals can be kept for some time, without cruelty, in confinement; and a more intimate knowledge of certain of their habits can be thus obtained. The practice of keeping pets is, however, to be encouraged only when every possible care is taken to secure the comfort of the captives. To understand the internal structure of an animal, dissection is necessary. This consists in exposing and separating the internal organs of the dead animal from each other, in order to notice their mutual relation. A careful outline drawing of every dissection should be made and preserved. The student should make it a rule never to kill any animal unless for some useful purpose, and then to do so in the quickest and most painless manner.