129 



larva ; fourth, fifteen to tweuty cercarite, developing troiu each redia 

 and escaping from the snail; fifth, the encysted cercarijB, which after 

 having been swallowed by a lamb develop into adult tiukes. 



This life history is fully as wonderful as any occuriug in nature. Ac. 

 cording to it, at least seventy-five young flukes under favorable sur- 

 roundings could develop from a single egg. As the proper conditions 

 are scarcely' ever fulfilled, there are but few of those which meet with 

 all the requirements for develoi)ment. 



The disease created by these peculiar parasites is known by many 

 names, the most popular of which is Liver Rot, a term expressive of the 

 chief patholdgic symptom. Aqueous Cachexia, Rot, Rot Dropsy, Sheep- 

 Rot, Liver-Disease, Liver Fluke, Jaundice, Yellows, Verminous Phthisis 

 of the Liver and Ictero-Verminous Cachexia, are other names for the 

 disease, each being expressive of some of its symptoms. 



The, symptoms, according to Neumann {Maladies Parasitaires), to whom 

 the writer is indebted for the greater part of this article, may be divided 

 into four periods, viz : 



(1) Period of immignitio7i.— This is the period in which the parasite 

 invades the liver. In this stage the flukes are small and do not cause 

 excessive disturbances. This period lasts from four to thirteen weeks. 

 It is probable that it lasts as long as tlie weather remains favorable 

 for the development of young flukes and sheep are kept on Infested 

 pastures. 



(2) Period, of anmnia. — This ordinarily coincides with the months of 

 November and January, or after the lapse of thirteen weeks from infec- 

 tion. The sheep are less lively ; the mncous membranes about the eyes, 

 the nose, and the gums, the internal surface of the ears and the skin, are 

 all paler than in well sheep. The appetite is still good, and the animals 

 have a tendency to fatten, caused, according to Simouds, by a bett-T 

 assimilation of food from the increased flow of bile stimulated by the 

 young flukes. This fattening stage has been taken advantage of in 

 England by a dealer (Bake well), who purposely exposed the lambs he 

 wished to market early to the disease, that he might send fat lambs into 

 the market fiv^e or six weeks ahead of his neighbors. Sometimes the 

 appetite diminishes, thirst increases, and rumination is irregular. The 

 conjunctiva, the mucous membranes of nose and mouth, and the skin 

 are white, slightly tiuged with yellow. There is a slight oedema (puf- 

 finess); the skin is looser, feels pasty and soft to the touch wiiere bare; 

 the conjunctiva is infiltrated and puffy and the eye partially closed ; 

 the* wool becomes dry and brittle, is easdy ijufted oft', and sometimes 

 falls oft' of itself. Weakness appears more and more marked. There 

 is sometimes fever and quickened breathing. Palpation and percussion 

 indicate ascites. The dro[)pings are normal, but contain at the end of 

 this period numerous fluke eggs. Death may result in this stage from 

 apoplexy. 



23038 A p 9 



