CHAPTER III. 



GENERAL PHYSIOLOGICAL AND ANATOMICAL 

 OBSERVATIONS 



The matter embraced by the heading of this chapter will 

 offer for discussion many subjects of great interest to the 

 veterinary surgeon. Around some of them debate has for 

 many years waxed more than keen. Of the points in 

 dispute, some of them may be regarded as satisfactorily 

 settled, while others offer still further room for investi- 

 gation. 



In this volume we can only hope to deal with them in 

 brief, and must select such as appear to have the greatest 

 bearing on the veterinarian's everyday practice. 



Always prolific of heated discussion has been one ques- 

 tion : 'Are the horny laminae secreted by the sensitive?' To 

 answer this satisfactorily, it will be best to give a short 

 account of the mode of production of the hoof in general. 



A. DEVELOPMENT OF THE HOOF. 



Starting with the statement that it is epidermal in origin, 

 we will first consider the structure of the skin, and follow 

 that with a brief description of the structure and mode of 

 growth of the human nail, a short study of which will 

 greatly assist us when we come to investigate the manner 

 of growth of the horse's hoof. 



The Skin is composed of two portions, the Epidermis 

 and the Corium. 



The Epidermis is a stratified epithelium. The super- 



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