His passive attitudes consist of standing, sitting and lying. He stands little, sits more, and lies for a great part of each day. The standing habit has, of course, no influence upon his hair. In sitting he rests the chief weight of his body on the rounded, bursa-covered surfaces of his tuberosities of the ischium, in which there is nothing peculiar to himself. His fore legs are planted nearly upright on the ground and his hind legs doubled under him or projecting slightly to one or other side, as we saw in the case of the cow. The fore legs are obviously in no way affected as to the direction of the hair in the sitting posture, and the hind legs, being doubled up and subject to the direct downward weight of the body, are also free from the _sliding pressure_, which we shall see affects the fore limb when the dog lies prone. Thus of the three supports, fore legs, hind legs and tuberosities of the ischium, two are necessarily unaffected in their patterns of hair. The anatomical conditions of his tuberosities are very different in this respect. They are covered with a large slippery bursa just beneath the thick skin, and the slightest movement of this alert and restless animal, even of his head, conveys to this region a small change of position. He is virtually like a sick person on a water or air cushion, and we all know how very small movements of the body are felt in a slight stirring of the supported parts by these. The effect of this is that the hair over these bursæ is seldom at rest from external or extraneous forces, to say nothing of its own imperious constant growth of one inch in two months. In Fig. 38 one sees the hair-stream curving round the buttocks towards the region of these bursæ, and trying to reach the middle line. It meets with so much opposition that the very conditions for producing a reversed area are present and the result is just what one would expect to find. The pattern is formed exactly over the bursæ limited to this area, and it does not expand anywhere because there is no need for it to do so. So when one observes on the surface just below the tail a pattern, often in a black-and-tan terrier marked by a tan patch of hair, one reads the record of the long time spent by the dog in sitting as he meditates on some fresh or past escapade of “A Dog’s Day.” The statement just made that the hind leg does not share in the effects of pressure is not strictly correct; it applies to the _leg_ properly so called. But the upper part of the thigh exhibits a very clear reversal of hair due to the weight of the body acting here against the streams from the side of the thigh, which are seen endeavouring to make their way to the inner side. They are arrested by a long ridge of hair which marks the obstacle presented by the weight of the body acting here. This completes the story of the way in which sitting affects the hair of the dog, and is shown in Fig. 38. Lying Attitude.