95 



sail duct has become completely packed by the parasites. The adult 

 worms have embryos in their most distaut segments, which are ready 

 to be set free. These embryos escape from the host with the feces. 

 Until they reappear in the duodenum of another sheep, a quarter of 

 an inch in length, their history is unknown. 



A twnia infecting a lamb two months old, the youngest stage noticed, 

 is about a half inch long ; as the season advances it is joined by others, 

 and these increase in size. Four or five months afterward it is found 

 to be 4 or 5 inches in length, showing a monthly rate of growth of about 

 1 inch. From this time it gradually increases in size until the following 

 spring, when it becomes adult and capable of furnishing embryos for 

 infection of other animals. These embryos escape from the sheep, and 

 while many are destroyed a few- arrive at their destination in a second 

 animal. 



Disease. — The influence that the presence of Twnia fimbriata has on 

 the life and health of its host is not inconsiderable. The ultimate loss 

 is seen when lambs which should be fat and strong are not, and die dur- 

 ing the colder weather while the fatter ones survive. This loss, where 

 the hosts do not die, can not perhaps be accurately estimated, but is 

 nevertheless present, for thin, hide-bound, dwarfed sheep are not 

 valuable for mutton, nor do they produce as much wool as they other- 

 wise would. 



So slowly are the parasites hatched, so slowly do they grow, and so 

 gradually do the symptoms develop, that the tceniai are present in con- 

 siderable numbers and size before systemic disturbances in the lambs 

 present themselves. An experienced ranchman will probably notice 

 towards September that some of the lambs are not growing as they 

 should. Later in the fall the symptoms increase. In November the 

 lambs, which are by this time thoroughly infected with a number of 

 strong, tenacious parasites, show the disease quite plainly. 



The disturbances finally shown are induced at first by the local irrita- 

 tion produced by the worms attaching themselves to the villi of the 

 intestinal walls and causing a greater secretion through their strong 

 vermicular action. A continuance and increase of this irritation caused 

 by the growth of the parasite and an accession of other parasites, 

 finally excites chronic catarrhal inflammation of the duodenum and bil- 

 iary duct. To these disturbances we must add those arising in the liver 

 from a plugging of the duct by the parasites, which grow so large that 

 they distend it to a comparatively large size. 



Dr. George C. Faville, in a report of the veterinary' department of the 

 State Agricultural College of Colorado for 1884, describes the J>os^ 

 mortem appearances of these animals as follows : 



, Organs of thorax were normal. In the abdominal cavity I found the stomach filled 

 with a mass of semi-digested loco leaves. The liver Was normal in appearance ; gall 

 bladder filled with greenish-colored bile. In the duct running from the gall bladder 

 to the small intestines, I found a mass of tapeworms {Tmnia expansa). The small in- 

 testine I found filled with a mass of these worms, varying in length from 6 inches to 



