GID OR STAGGERS. 



TAENIA CCENUKUfc?, Kiieb. 

 Plato XI, Figs. 1 to 4. 



The disease wbicli is popularly known as gid, sturdy, staggers, or 

 turusick in sheep, is caused by the ])resence of»a i)arasite living iu the 

 brain. This parasite is closely related to T(mia marginata. It lives iu 

 about the same way, but differs from it in detail. It is known as T. 

 cceimrusm its adult state, and as Gu-nurus ccrcbralis in its cystic state — 

 the stage in which it infests sheep. 



Method of infection. — Sheep become infected with this dangerous para- 

 site while pasturing or drinking where dogs liave scattered the eggs iu 

 their wanderings through the country. In the West the eggs may also 

 be scattered by the wolves, coyotes, and foxes, which may harbor the 

 adult parasite. 



Life history. — The eggs of Tania ccenm'us, after being taken with the 

 food or drink, are hatched within the stomach of the sheep and make 

 their way through its walls. They then migrate either actively, by 

 forcing their way through the connective tissues, or passively, as is 

 generally believed to be the case, by getting into the circulatory system, 

 and are carried from thence into various portions of the body. Those 

 arriving in the spinal canal and cranial cavity seem to thrive and grow, 

 while the others, which may have reached the heart, lungs, and dia- 

 phragm, grow for a 1;ime and then perish. 



Description of cystic stage. — Having arrived iu the brain cavity, the 

 young embryo migrates upon the surface of the brain much as the em- 

 bryo of Tccnia onarginata does through the liver substance. The gal- 

 leries it makes are sinuous. They begin at a point and slowly increase 

 with the growth of the parasite and run in any direction. In from two 

 to three mouths after the lirst invasion of the brain the cysts have 

 grown as large as a hazel-nut, or about a half inch in diameter. When 

 examined closely they will be fouud incased in a thick outer skin, a sac 

 made by the membranes ot the brain. Out of these sacs the parasites 

 may be loosened, and these resemble the cysts of T. marginata. It 

 differs, however, in a very important particular — instead of having a 

 single knob attached, tens or hundreds of these knobs may be seen as 

 little dots hanging from the inner surface into the fluid of the cavity, 

 (see Figs. 3 and 4). Each of these dots can evert itself, or push its head 

 out, and will then be seen by the aid of a glass to be a perfectly dc- 



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