ORDER V  .—Tetracotylea (Taeniidae) . Scolex with four suckers, rarely hooked, and with a rostellum . Mostly parasitic in homoiothermic (warm-blooded) vertebrates . Selected forms: Taenia solium, intestine of man (fig . 3, C) . T. saginata (fig . 3) without hooklets on the rostellum; intestine of man . T. murina, in the rat and mouse, the adult in the lumen of the intestine, the larvae in the villi . ,This species therefore undergoes no change of host . Cystotaenia coenurus, intestine of dog and wolf, larva (a coenurus, fig. i i) in the brain of sheep; allied forms occur mature in the dog and larval in the rabbit . Echinococcifer echinococcus, a minute form with only three to five proglottides, in dog, wolf, jackal . Larval stage a multilocular sac (fig .

II B) with many scolices; found in man, ungulates, carnivores, rodents and monkeys . Table of Cestodes found in Man Dibothriocephalus latus (L.) Plerocercoid

Pike, perch, trout, &c . Dibothriocephalus cordalus Unknown (Leuck.) Diplogonoporus grandis (Blanch.) Dipylidium caninum (L.) . Cysticercoid Trichodectes canis; Pulex serraticeps; P. irritans Ilymenolepis dirninnata Cysticercus Asopia far- (Rud.) inalis Anisolabis annulipes Insecta Acisspinosa Seaurus striatus H. nana (v . Sieb.) . Cysticercus Insects and myria- pods Drepanidotaenia lanceolata Cysticercoid Cyclops, Diaplomus (Bloch) Davainea nzadagascarensis Unknown (Day.) Davainea (?) asiatica Taenia solium (L.) . 7'. saginata (Gotze) T. africana (v . Linst.) . T. confusa (Ward) . T. echinococcus (v . Sieb.) . and J .

Hornell, Ceylon Pearl Oyster Report, London, The Royal Society, part ii. p . 77, part iii. p . 449, part v. p . 43, 1903—7; (7) W . B . Spencer " Gyrocotyle=Amphiptyches," Trans . Roy . Soc., Victoria, vol. i . (1889); (8) S . Goto, " Homology of Genital Ducts," Centralbl. f . Bact. u . Parasilenkunde, vol .

14 (1893), p . 797; (9) Mrazek, Archigetes," Verhandl. d. bohm . Akad . Sci . (

Prague, 1897) . Full references to further literature will be found in Braun's works . (F . W . GA.) Medicine.—For practical purposes we have only three varieties of tapeworms to deal with as inhabitants of the human alimentary canal: Taenia saginata, the beef tapeworm; Taenia solium, the pork tapeworm; and Dibothriocephalus latus, the fish tapeworm . The first of these is prevalent in countries where much and imperfectly cooked beef is eaten, and where cattle in their turn are exposed to the infection of the tapeworm ova . Comparatively uncommon in Western Europe, the Taenia saginata is common in Eastern Europe, Asia and South America . It is calculated that in the North-West Provinces of India 5 per cent. of the cattle are affected with cysticerci owing to the filthy habits of the people .

Measly beef (that infected with the Cysticercus bovis) is easily recognized . In

Berlin the proportion of cattle said to be found infected on inspection in 1893 was 1 in 672 . Cold storage for a period of over three weeks is said to kill the cysticercus . The tapeworm most frequently found in man in Western Europe is the Taenia solium, which is constant wherever pork is consumed, and is more common in parts where raw or imperfectly cooked pork is eaten . In North Germany the mature tapeworm was found on post-mortem examination once in every 200 bodies examined, while its embryo, the Cysticercus cellulosae, was found in I in every 76 bodies . In France, Great Britain and the United States the prevalence is not so great . The Dibothriocephalus latus is not generally found except in districts bordering the Baltic Sea, the districts round the Franco-Swiss lakes and Japan . In St Petersburg 15 per cent. of the in-habitants are said to be affected . The eggs are free in fresh-water lakes and rivers, where they enter the bodies of pike, turbot and other fishes, and are thus eaten by man . In many instances the existence of a tapeworm may not cause any inconvenience to its host, and its presence may be only made known by the presence of the proglottides or mature segments in the stools . In the Taenia solium it takes 3 to 32 months from the time of ingestion of the embryo to the passage of the matured segments, but in the Taenia saginata the time is only about 6o days . The segments of the Taenia solium are usually given off in chains, those of the Taenia saginata singly .

In a number of cases there are colicky pains in the

abdomen, with diarrhoea or constipation and more or less anaemia, while the Dibothriocephalus latus is capable of producing a profound and severe anaemia closely resembling pernicious anaemia . The knowledge of the presence of the parasite adversely affects nervous people and may lead to mental depression and hypochondria . Nervous phenomena, such as chorea and epileptic seizures, have been attributed to the presence of the tapeworm . The prophylaxis is important in order to limit the spread of the parasites . All segments passed should be burnt, and they should never be thrown where the embryos may become scattered . Attention should be paid to the careful cooking of meat, so that any parasite present should be killed . Efficient inspection of meat in the abattoirs should eliminate a large proportion of the diseased animals . In the treatment of a case where the parasite is already present, for two days previous to the employment of a vermifuge a light diet should be given and the bowels moved by a purgative . For twelve hours previously to its administration no food should be given, in order that the intestinal tract should be empty so as to expose the tapeworm to the full action of the drug . The vermifuge is given in the early morning, and should consist of the liquid extract of felix mas, male fern, one drachm in emulsion or in capsules to be followed in half an hour by a calomel purgative . Castor-oil should not he used as a purgative . Pomegranate root, or, better, the sulphate of pelletierine in dose of 5 grains with an equal quantity of tannic acid, may be used to replace the male fern .

In from 5o to 8o per cent. of cases the entire tapeworm is expelled . The

head must be carefully searched for by the physician, as should it fail to be brought-away the parasite continues to grow, and within a few months the segments again begin to appear .