82 presidential address section d. 



Paragonimiasis. 



'i'he lung riuke, Pantgonimns icestcriiunii, is the cause of 

 human puhnonary distomiasis accompanied by haemoptysis in 

 the East, and has been reported from North America and from 

 South America. 



Parugonimus westermani is a small, somewhat oval fluke, varying 

 from 8mm. to 16mm. in length, by 4mm. to 8mm. broad, and 3mm. to- 

 4mm. thick. Its colour is reddish brown. The whole cuticle is covered 

 with scale-like movable spines. The oral sucker is spherical and terminal, 

 very slightly smaller than the acetabulum. The alimentary canal consists- 

 of a short oesophagus which branches into two sinuous caeca. The small 

 genital orifice opens near the margin of the ventral sucker. There are 

 two testes, arranged laterally, one slightly anterior to the other, lying 

 just behind the branched uterus. The ovary is opposite and slightly 

 posterior to the uterus. The yolk glands are lateral and almost meet 

 dorsally, but on the ventral side they only extend as far as tlie intestinal 

 caeca. The excretory system is well developed, and extends from the 

 pharynx backwards. 



The life history of Paragonimus has been worked out mainly 

 by Japanese investigat-ors, chief among whom may be mentioned 

 Nakagawa, Kobayashi and Sadao Yoshida. It may be mentioned 

 that Nakagawa and Yoshida worked independently of each other, 

 but published their results about the same time, and that each 

 worker came to the same conclusions. 



It was ascertained and published about 1916 that the encysted 

 stages of Paragonimus westertnani had been found in certain river 

 crabs. By feeding laboratory animals such as rats and cats with 

 these crabs, adult Paragonimus were obtained. Nakagawa (1916) 

 in Formosa found that the " red " crab, Gcothclphusa (Pofainoii) 

 obtusipes Simpson, the " dung " crab Geothelphusa (Po/inKo//) 

 dehaanii White, and the " 'hairy " or " fur " crab, Eriochcir 

 japnnicus de Haan, were the hosts of the encysted cercarite of 

 P. ivestermani. Kobayashi has found that Astacus japonicus also 

 harbovirs the agamodistomes in certain parts of Korea. Fresh 

 raw crab is used by the Koreans as an antipyretic and diarrhoea 

 remedy. 



In these Crustacea, the encysted larval flukes occur in the 

 liver, the muscles and the gills. The thickwalled cysts are 

 rounded to oval, and measure about 0"3 mm. to 0"4 mm. in 

 diameter. The larva has a short, thick body, and lies straight, 

 not twisted, in the cyst. The body is covered with short spines. 

 The oral sucker is about 0"08 mm. to 0"11 mm. in diameter, 

 the ventral svicker being 0"07 mm. to 0'12 mm. in diameter. The 

 short cBsphagus leads to a bifurcate, thick, undulating intestine 

 that lies parallel to the long, thick, excretory vesicle. 



Nakagawa (]916) found that in Formosa the primary hosts 

 of the lung fluke Avere the snails Melania lihertiiia and M. 

 ohliqucgranosa. Kobayashi (1919) found that in Korea Melania 

 pancicincta and M. gottschei harboured the cercariae. He also 

 has bred the ccrcariai from the miracidia in these snails. 



The miracidia, on being liberated in water from ova contained 

 in sputum, penetrate species of Melania and each develops 

 beneath the skin of the snail into a sporocyst, within which a 

 redia is produced. This redia migrates into the liver of the snail,. 



