97 



coats of the abdomen, and otber spaces where serous membrane par- 

 tially or entirely surrounds an organ are noticeably infiltrated. 



These conditions hold in lambs and older sheep. Between the worst 

 aUected and entirely healthy individuals there are many grades. The 

 syujptoms and pathologic lesions are those of malnutrition, and aside 

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

 from the sjstemic lesions caused by other parasites, or from innutri- 

 tions food, or from any cause that would prevent the animals obtaining 

 and assimilating nourishing 4'ood. A variety of other causes would 

 produce the same lesions. 



The parasites may produce their evil results as follows : Their vermic- 

 ular actions cause increased secretion of the intestine where they are 

 lodged, both l)y direct irritation and sympathetically, /. e., the adjacent 

 intestine secretes more than it ordinarily would by acting in sympathy 

 with the infected portion. This hypersecretion soon becomes abnormal, 

 and the secreting membranes become so changed that they can no 

 onger act physiologically. Its best purpose is in furnishing the para- 

 site 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 

 lemptied at their proper times, and any interference with this flow 

 deranges healthy digestion. The damming back of the gall reacts on 

 the secretion in tlie 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 functions 

 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 prei)aration of food 

 for its assimilation through the intestinal wall, resulting in a loss to 

 the animal of nutrient material. The duodenum 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 distvirbances are each slight, but when combined and con- 

 tinued 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 dis- 

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

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

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

 ished condition of the infected animals. From these causes proceed the 

 imperfect nutrition of the various organ's and the dropsical effusions 

 resulting therefrom. 



From this state of mal-nutrition all of the systemic disturbances can 

 result. The staggering gait maj' arise from the weakened muscular 

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

 23038 A P 7 



