OCCURRENCE OF CESTODES IN DOMESTIC ANIMALS.[103]—Among domestic animals, the dog is, undoubtedly, the most frequently attacked by Taeniae. Six species of _Taenia_ (_T. serrata_, _marginata_, _coenurus_, _echinococcus_, _krabbei_, and possibly _T. serialis_), _Dipylidium caninum_ (the commonest form), _Mesocestoides lineatus_, and three or four species of _Bothriocephalus_ have been found in the dog. The table of life-histories (p. 83) shows that sheep, rabbits and other Rodents serve as the intermediate hosts, in which the cystic stages of the species of _Taenia_ are found. Hence the prevalence of _T. serrata_ in a given locality is connected with the abundance there of the rabbit and hare, in which the larva (_Cysticercus pisiformis_) occurs. _Bothriocephalus cordatus_ develops from the young stage present in the fish which the Icelanders give to their dogs. In Iceland and certain parts of {82}Australia _T. echinococcus_ infests one-third to one-half the number of dogs examined; a fact connected with the frequency of _Echinococcus_ 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 35 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, Roe, Antelope, Reindeer, Dromedary—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.