172 REPORT OF THE BUEEAU OF ANIMAL INDUSTRY. 



more usual to find the parasites of various sizes, indicating a con- 

 tinuous infection. The retention of food and liquids for some little 

 time in the rumen and reticulum may account for this in part. 

 These varying sizes continue from May until December. Sheep ex- 

 amined in May presented various sizes, and indicated infection in 

 former months. No other data showing infection during winter 

 months were obtained. The smallest tseniae are found in the duode- 

 num ; those found in the gall ducts are larger. Tsenia less than 

 2 mm long have been found in the duodenum after the gall duct has 

 become completely packed by the parasites. The adult worms have 

 embryos in their most distant segments, which are ready to be set free.- 

 These embryos escape from the host with the f eces. Until they re- 

 appear, in the duodenum of another sheep, a quarter of an inch in 

 length, their history is unknown. 



A tsenia 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. 



PATHOLOGY. 



The influence that the presence of Tcenia 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 during 

 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 taenige are present in 

 considerable 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 ought. Later in the fall the symptoms increase. In November 

 the lambs, which are by this time thoroughly infected with a num- 

 ber of strong, tenacious parasites, show the disease quite plainly. 



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

 ritation 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 irrita- 

 tion caused by the growth of the parasite and an accession of other 

 parasites, finally excites chronic catarrhal inflammation of the duo- 

 denum and biliary 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 

 post 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 appear- 



