Study on Metagonimus yokogawai(Katsurada, 1912) in KoreaI. On the metacercaria, its distribution in the second intermediate host and the development in the final host

The metacercariae of Metagonimus yokogawai were isolated from the sweetfish Plecoglossus altivelis, clollected at Hwagae, South Kyongsang Do, one of the newly known endemic foci of metagonimiasis in Korea. The body structure of metacercaria of M.yokogawai was described and the measurements of the excysted metacercaria were also made. In order to know the distribution of metacercariae within the host, the rate of infection and the intensity of infection, a total of 10 sweet fishes was examined and it was found all infected, from which a total of 38,511 metacercariae was isolated. The number of metacercariae in a fish varied from 219 to 14,427. The average number of metacercaria per fish was 3,851. The distribution of metacercariae in the four divided parts of fish was observed in the following order; number of metacercaria in the muscles; 2,417 (62.8%), in the subcutaneous tissues; 1,126.9 (29.3%), and on the scale; 291.9(7.7%). The development of the metacercaria of M. yokogawai in the mouse host was experimentally traced every day for 10 days after infection . In an earlier period of infection, the growth rate of the genital primordia was distinctly high, particularly in the testes. The seminal receptable and seminal vesicle became clearly recognized in measurable size at 4 days after infection. The vitelline follicles and their ducts were also first visible in the living specimens at 6 days after infection. The oral sucker was larger in size than the ventral sucker in an early stage of the worms, however after 7 days after infection it reversed. The posterior part of body began to extend since two days after infection. Fully matured worms were able to collect only after 7 days after infection. At this stage, the body of worm became 0.7 mm long and 0.3 mm wide. The first positive appearance of eggs in the uterine tubule and in feces was on the 6th day and 10th day of infection, respectively. In an earlier stage of infection, the worms were found mostly in the upper portion of small intestine and the recovery rates of the worms were high, however according to the course of infection in later stage they were seen rather in the lower part of the intestine and the recovery rate also decreased.

Studies on the parasitic helminths of Korea III. Nematodes and cestodes of rodents

A survey for nematode and cestode parasites of rodents in Korea has been carried out at the areas of Chulwon, Kumwha, Pochon, Paju and Chungpyong, Kyunggi-Do. A total of 300 rodents of seven species was examined, comprising of 219 A. agrarius, 33 R. norvegicus, 8 R. alexandrinus, 14 Mus musculus yamashinai, Microtus fortis pellceus, 21 Crocidura russula and a Cricetulus trition nester. The following fifteen species belonging to thirteen genera were identified: NEMATODA: Heterakis spumosa, Syphacia obvelata, Nippostrongylus muris, Protospirura muris, Capillaria hepatica, Capillaria sp., Heligmosomum sp., Heligmosomoides sp., Rictularia sp. and Gongylonema sp. CESTODA: Hymenolepis nana, Hymenolepis diminuta, Raillietina coreensis, Paranoplocephala sp. and Cysticercus fasciolaris(the larva of Taenia taeniaeformis).