393 



CHAPTER XIX. 



Internal Parasites. 



general remarks sketch of the anatomy of the organs of 



digestion leeches bots tape worms worms. 



General Remarks. 



The "General Remarks on Parasites" made on p. 130 et seq., 

 apply equally well to the subjects of this chapter. It would have 

 been more correct thoug'h less convenient when writing in popular 

 language, for me to have put at the head of this chapter, " Non- 

 microbic Internal Parasites." Parasites may be divided into 

 those which are microbes (microscopic organisms), and those 

 which we may see with the naked eye, or with a magnifying 

 glass of low power. In the present chapter, I shall write 

 solely about the latter, and shall reserve for Chapter XXII. 

 any remarks I may have to make about the former with reference 

 to their capacity as producers of infective diseases. Diseases pro- 

 ducing microbes belong, as a rule, to the vegetable kingdom. 



The parasites w^hich I shall consider in this chapter are those 

 of the more common kinds that invade the internal organs of the 

 horse. 



Sketch of the Anatomy of the Organs of 

 Digestion. 



THE DIGESTIVE APPARATUS of the horse, like that of man, consists of 

 the alimentary canal, in which the food is digested ; and various organs which 

 promote the digestion and transit of the contained food. 



THE ALIMENTARY CANAL is formed of the mouth, pharynx, gullet, 

 stomach, small intestine, and large intestine. 



THE MOUTH consists of the lips, cheeks, tongue, hard palate, soft palate, 

 and the surfaces in which the teeth are implanted (dental arches). The lips help 

 to take up solid and liquid food, and to retain it and also saliva in the mouth. 

 The cheeks, conjointly with the tongue, place the food between the back teeth, 

 to be ground up. The tongue also plays a large part in swallowing. The 



