42 



connected by prolongations of their substance through small 

 conduits in the bone called the Haversian canals. Their func- 

 tion is to give support to the bone within and without, and to 

 furnish a bed whereon the nerves, blood-vessels, and absorbents 

 can ramify. Bones are most amply supplied with nutrient 

 materials by these means, and their disintegrated particles 

 probably carried away by the absorbents. I say, probably, be- 

 cause some physiologists consider it doubtful, at least, whether 

 absorbent vessels exist in bone. The coronal and navicular 

 bones present nothing exceptional as regards their periosteal 

 coverings, but there is a very remarkable peculiarity concern- 

 ing the periosteum of the coffin-bone which I think throws 

 much light upon the constitution and functions of the sensitive 

 laminae, a just appreciation of which has a most important 

 bearing upon the question of shoeing, either in health or 

 disease. Microscopic " anatomy, physiology, and pathological 

 experience," perfectly harmonize in the views I have taken 

 upon this master question of the foot, and the practical meas- 

 ures I have based upon them. 



THE SENSITIVE LAMINAE. 



Mr. Spooner says : " The sensitive laminae are somewhat 

 similar in appearance, but very different in structure to the horny 

 laminae, with which they are connected by a dove-tailed union, 

 each horny plate being received between two sensible plates, 

 and vice versa. They are firmly attached by means of elastic (?) 

 membranous structure to the irregular surface of the os pedis ; 

 and are also continued on the lower position of the side car- 

 tilages, where they correspond to the horny laminae, on the 

 inside of the bars of the foot. The sensitive laminae, as their 

 name imports, are extremely sensitive and vascular, and as Mr. 

 Percival says, are composed of a double transparent ?nembrane, 

 plaited as it were around the bone, so that one of the sides of 

 each laminae is in close contact with another, and the other 

 side opposed to a horny lamina. The sensible laminae used to 

 be considered as highly elastic, and writer after writer having 



