82 PLATYHELMINTHES CESTODA CHAP. 



Australia T. echinococcus infests one-third to one-half the number 

 of dogs examined ; a fact connected with the frequency of Ecliino- 

 cocous in man in these countries. 



In sheep the most noteworthy and dangerous parasite is 

 Coenurus cerebralis (or the cystic stage of the dog-taenia, T. 

 coenurus), which gives rise to the disease known as " gid " or 

 " staggers." It is found in various parts of the brain or spinal 

 cord, and the symptoms differ according to the position of the 

 parasite. If this presses upon one hemisphere the sheep describes 

 circles and finally falls : if on the optic lobes, the eyes are 

 affected : if the pressure affects the cerebellum the movements 

 of the sheep are uncertain and incoordinated. Four or six 

 weeks after the appearance of the symptoms, death results from 

 cerebral paralysis, or from general debility, and the loss of sheep 

 incurred by this disease (happily less frequent in England than 

 formerly) has been calculated by Youatt at a million for France 

 annually ; at 3 5 per cent of the flocks for England in bad seasons ; 

 and about 2 per cent for Germany. Besides sheep, which are 

 most subject to " gid " during their first year, various ruminants 

 Goat, Ox, Moufflon, Chamois, Eoe, Antelope, Eeindeer, Drome- 

 dary are attacked in the same way. A similar form, Coenurus 

 serialis Baill., is common in the wild rabbit in this country, and 

 in Australia in the hare and squirrel. It forms large swellings 

 in the connective tissue of various parts of the body, but usually 

 does not affect the health of the host. It is not known in what 

 carnivore Taenia serialis Baill. normally occurs. Experiments 

 have, however, shown that it develops rapidly in dogs. 



The preventive measures which are steadily diminishing the 

 prevalence of the Cestode parasites in man in some parts of 

 Western Europe cannot be dealt with here, but it may be 

 noticed that the Jewish observance with regard to swine is the 

 surest preventive measure against taeniasis and trichinosis. 

 Careful inspection of meat and general cleanliness, are the lead- 

 ing measures that in these hygienic matters secure the greatest 

 immunity from disease. 



