Diseases of cattle, sheep, goats Diseases of cattle, sheep, goats and swine diseasesofcattle00mous Year: 1920 CHAPTER II. PHTHIRIASIS. The term plithiriasis is applied to infestation of the sldn with lice. Causation. These diseases are due to the presence of various para- sites which live by destroying the epidermic scales, or by piercing the superficial layers of the skin. They are of a greyish-yellow colour, and belong to the genera Hcematopinus and Tricliodrctes. The Hfematopinus forms have pointed heads, and are equipped for

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