EEPOET OF THE BUREAU OF ANIMAL INDUSTRY. 



The symptoms and pathologic lesions are those of innutrition, and 

 aside from the lesions of the duodenum and liver are not materially 

 different from the systemic lesions caused by other parasites, or from 

 innutritions food, or from any cause that would prevent the animals 

 obtaining and assimilating nourishing food. A variety of other 

 causes would produce the same lesions. 



The parasites may produce their evil results as follows : Their 

 vermicular actions cause increased secretion of the intestine where 

 they are lodged, both by direct irritation and sympathetically, i. e., 

 the adjacent intestine secretes more than it ordinarily would by act- 

 ing in sympathy with the infected portion. This hyper-secretion 

 soon becomes abnormal, and the secreting membranes become so 

 changed that they can no longer .act physiologically. Its best pur- 

 pose is in furnishing the parasite with more nutritious fluid. The 

 plugging of the gall ducts not only stops the gall from flowing at 

 proper times, but dams back that which is secreted during digestion, 

 and allows it to slowly ooze out after it is needed. When the ducts 

 are unobstructed the bladder and ducts are emptied at their proper 

 times, and any interference with this flow deranges healthy digestion. 

 The damming back of the gall reacts on the secretion in the smaller 

 ducts, and this in its turn reacts on the physiological functions of 

 the liver cells. 



The disturbance of digestion due to this impairment of the func- 

 tions of the liver and duodenum has not a merely local effect. In 

 the upper parts of the small intestine important digestive changes 

 take place, and the disturbance of any of these prevents the proper 

 preparation of food for its assimilation through the intestinal wall, 

 resulting in a loss to the animal of nutrient material. The duo- 

 denum is held to be a very irritable organ, diseases in it causing 

 reflex disturbances of various kinds. These reflex actions also lead 

 to many systemic disturbances. Now these disturbances are each 

 slight, but when combined and continued through weeks and months 

 they cause the results just described. To one seeing a half dozen 

 or more worms taken from the intestine of a sheep, the worms 

 do not seem to be a sufficient cause of disease. The disturbance 

 caused by one worm in man gives rise to even greater systemic de- 

 rangements. The non-assimilation of food and reflex irritation pro- 

 duced by the tape-worms seem to me to be the chief causes of the 

 impoverished condition of the infected animals. From these causes 

 proceed the mal-nutrition of the various organs and the dropsical 

 effusions resulting therefrom. 



From this state of mal-nutritlon all of the systemic disturbances 

 can result. The staggering gait may arise from the weakened mus- 

 cular system; the absence of fat from non-deposition of more and the 

 consumption of that heretofore deposited; the serous effusions from 

 the weakened condition of the system; and the foolish actions from 

 the long-continued mal-nourishnient of the brain. 



Sheep do not die from the tape-worm disease alone. The greatest 

 losses are, the ranchmen say, among the lambs and yearlings. The 

 majority may die during cold storms, either from freezing or from 

 suffocation while piling upon each other for warmth. They may 

 starve to death either from inability or lack of desire to eat. They 

 may die from other diseases. The tape-worm disease appears to ren- 

 der them more liable to other affections and less able to withstand the 

 inclement season. It is, therefore, indirectly chargeable with the loss. 

 Were the infected sheep not to die, the parasite is still a cause of pe- 



