FITZIPYGRJM'S TREATISE. 5SS 



Speaking of the admirable arrangement of the crust-fibres 

 for sustaining the weight by their almost perpendicular di- 

 rection, 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, t/iei/ 

 are placed in layers in a horizontal position. The sole, 

 therefore, from its construction, is unable to sustain freight 



or pressure Whilst the structure of the crust is in 



fibres, standing with their ends on the ground, the struc- 

 ture of the sole consists of fibres placed in layers hori- 

 zontally. The difference in power of sustaining weight, 

 which arises from this difference in the position of the 

 fibres, will be easily seen. Anything standing perpen- 

 dicularly 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 im- 

 portant, on account of its position, that no undue weight 

 should be put upon it. . . . The fibres of the insensitive 

 sole mav be compared to layers of fibres of hay, placed 

 horizontally. These will necessarily crush in under a com- 

 paratively 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 miscon- 

 ception 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 con- 

 siderable share of the animal's weight, as well as contact with 

 the ground. This is a fact worthy of bearing in mind ; as 



