PRESIDENTIAL ADDRESS — SECTION D. 85 



infection. In about 10 days, the rediae reach the livers of the 

 snails, and are then about 0'5 mm. long. After about 35 days, 

 daughter redite and cercarise are produced. Each redia contains 

 from four to seven cercarise, which are simple-tailed, have a body 

 measuring 0'21 mm. to 0'23 mm. long and from 0"1 mm. to 

 0'15 mm. broad. The oral sucker is slightly larger than the 

 ventral. The cercariae leave the water ultimately and encyst on 

 vegetation, forming a somewhat flattened disc-shaped cyst. 

 When such cysts were fed to clean pigs fully grown specimens 

 of Fasciolopsis were found at the autopsy. 



Several species of Fasciolopsis have been described, and 

 opinions differ considerably as to whether all the species are 

 valid. Ward considers that F. buski, F. rathousi, F. fullehorni 

 and F. goddardi are distinct species, basing the species on 

 differences in the spines of the cirrus sac. Odhner, on the other 

 hand, considers that the various species should be merged into one. 



The interesting small fluke, H&terophyes heterophyes is 

 known as a parasite of man in Egypt, Anglo-Egyptian Sudan, 

 and China. It also occurs in cats and dogs in these countries. In 

 1915, Onji and Nishio described a second species, H. nocens, 

 from man. So far, it has only been reported from the south-west 

 part of the largest of the Japanese islands, but between 20 per 

 cent, and 30 per cent, of the inhabitants are infected. 

 Heterophyes nocens resembles H. heterophyes, but is even 

 smaller, being only 0'9 mm. to 1*1 mm. long. Its extra genital 

 sucker has some 60 rodlets, while H. heterophyes has from 60 

 to 75. Infection is contracted by eating the raw flesh of the fish 

 Miujil japonicus, in which encysted larvae of the fluke occur. 

 The source of infection of the fish is unknown. When clean dogs 

 are fed on infected Mugil capito (a " harder ') eggs of the fluke 

 appear in the faeces 7 to 8 days after the infective feed, so 

 that the development of the parasite in the vertebrate host is 

 rapid. 



Echinostomes in man have been known for some time. Thus, 

 Echinostoma ilocanum was reported from the intestine of 

 Filipinos in 1908 and E . malayanum from the intestine of Malays 

 in 1911. The life-history of the human fluke remained unknown 

 till it was recently worked out by Ciurea in Eoumania on 

 Echinochasmus perfoUatus, though it is of interest to recall that 

 one of the earliest Trematode life-histories to be worked out was 

 that of the Echinostome of the duck. Ciurea fed clean cats and 

 dogs on various cyst-infected Danube fishes, such as Idus idus. 

 Tinea tmca, Scnrdinius erythrophthalmus, Abramis abramis, 

 Esox lucius, Aspius aspius and Blicca bjorkna, and found adult 

 Echinochasmus perfoUatus in them. The encysted larvae occurred 

 in the fish only along the lateral line. They were minute, being 

 only about 0*197 mm. long and 0'147 mm. broad. Some of the 

 encysted larvae were covered with fine spines. The oral sucker 

 was slightly larger than the ventral adoral disc, which bore a 

 series of 27 spines. The molluscan or other first host in which 

 the parthenita and cercariae are produced is not yet known. 

 Ciurea believed that infection of man with Echinostoma ilocanuvi 

 and E. malayanum is probably due to eating raw infected fish. 



