Speaking of the admirable arrangement of the crust-fibres for sustaining the weight by their almost perpendicular direction, he adds: 'In the sole, on the other hand, all these conditions favourable for sustaining weight are wanting. The fibres are much less substantial than those of the crust, they are not so closely connected together, and, lastly, they are placed in layers in a horizontal position. The sole, therefore, from its construction, is unable to sustain weight or pressure. . . . . Whilst the structure of the crust is in fibres, standing with their ends on the ground, the structure of the sole consists of fibres placed in layers horizontally. The difference in power of sustaining weight, which arises from this difference in the position of the fibres, will be easily seen. Anything standing perpendicularly will sustain a much greater weight without yielding, than it will if placed horizontally. . . Whilst, then, from its construction it is evident that the insensitive sole is not intended to bear weight, it is also most important, on account of its position, that no undue weight should be put upon it. . . . The fibres of the insensitive sole may be compared to layers of fibres of hay, placed horizontally. These will necessarily crush in under a comparatively light weight, for neither by their position nor by substance are they calculated to sustain weight or pressure.'
This is quite a mistake; and is founded on a misconception of the anatomical structure of this part, which was first promulgated by Girard. The horn-fibres of the sole are secreted, and grow in exactly the same direction as those of the crust, and are capable of sustaining a considerable share of the animal's weight, as well as contact with the ground. This is a fact worthy of bearing in mind; as
