Academician K. I. Skrjabin was an outstanding Soviet scientist-helminthologist who greatly contributed to the advance of biological, veterinary and medical sciences.

The degree of resistance acquired by Schistosoma mansoni-infected mice against homologous challenge has been determined by perfusion of the animals within three weeks of the challenge, at which time the challenge-derived organisms were morphologically distinguishable from the primary infection which induced the resistance. The method has been compared with assays based on determination of the number of organisms migrating through the lung, and with perfusions at a later time when the challenge has matured. The results obtained with the three week perfusion method, showing that resistance was acquired by eight weeks after a primary infection, were confirmed by the longer survival of, and reduced egg excretion rates and tissue egg burdens in the experimental animals relative to respective challenge control animals. However, some discrepancy in challenge-derived worm numbers was found between animals perfused three weeks after challenge and those autopsied at later times. The possible reasons for this difference are discussed. The degree of resistance that was acquired was to some extent dependent on the size of the challenge infection.

Mice developed a partial resistance against homologous challenge with Schistosoma mansoni as early as two weeks after primary infections of 35 to 75 cercariae, and the degree of protection increased to an apparent maximum by 6 weeks. Animals given a primary infection of only 25 cercariae required a longer period to acquire maximum resistance.

Different groups of mice were infected with various single or repeated doses of larvae of Ancylostoma caninum. Considerable loss of larvae occurred in the immunised groups when compared with their counterpart unimmunised groups. Larval migration and distribution in the different tissues was less in immunised mice, as most larvae were expelled from the gastrointestinal tract. This resulted in a poor onward larval migration to liver, lungs, brain and muscle regions in immunised groups. The heavily immunised group infected five times was most affected and a significant lesser larval distribution in various organs and muscle region observed.

Balanotaenia newguinensis sp. n. is described from Tandanus brevidorsalis from Papua New Guinea. It differs from B. bancrofti from Australia primarily in being much smaller, having the testes and vitellaria beginning at the same level, and in having the gonopore posterior to the ovarian commissure. On the basis of this new species and B. bancrofti a new family of the order Caryophyllidea is described. Unlike any of the other three families the vitellaria and testes are in the cortical parenchyma. Drawings of the new species, comparative muscle distribution within all families of the Caryophyllidea, and photographs of the inner longitudinal muscles of B. bancrofti complement the description.

Mathevotaenia paraguayae sp. n. is described from Euphractus sexcinctus. It differs from M. didelphidis (Rud.) in having a transverse cirrus pouch anterior to the vagina. Monoecocestus mackiewiczi sp. n. was found in Phyllotis sp. It differs from M. parcitesticulatus Rego in having a much smaller scolex, a poral ovary, and a cirrus pouch 360 to 440 μm long. Other species reported are Taenia macrocystis, Taenia omissa, Spirometra mansonoides, Spirometra gracilis, Spirometra longicollis, Diphyllobothrium trinitatis, Atriotaenia parva, and Mathevotaenia tetragonocephala.

Allohymenolepis palawanensis sp. n. from a yellow-breasted sunbird, Nectarinia jugularis, in Palawan, Republic of the Philippines, is characterized by possessing a sucker diameter of 52–56 μm, a scolex of 120 × 157–166 μm, ovary 25–40 × 71–90 μm, and a vitelline gland of 17–25μm

A new genus of nematode (Paratrichosoma crocodilus) is described from Crocodilus novaeguinae. Adults have typical trichuroid features but elongated stichocytes (over 1 mm in female). Males are one third to one half as long as females and have no spicule or sheath.

The scanning and infective capacity of Schistosoma mansoni and S. haematobium miracidia were tested under limited exposure times in small volumes of water, and under increasing mutual dispersion in vessels of different sizes also over increasing horizontal distances, and under different flow rates of water. It was found that the miracidia of both species retained their infective capacity for up to 1 hour in the presence of susceptible snails. The infection rates decreased with decreasing miracidial densities but was still over 50% at 0.4–0.8 miracidia per litre. Both species of miracidia produced high (36–44%) infection rates in host snails situated at a distance of 5 m and equally high infection rates (39–40%) in snails placed in water flowing at a rate of 12–15 cm/sec.

The application of any of these physical factors in the control of schistosomiasis is discussed.

Stibocaptate (Astiban, Hoffman - La Roche) killed third stage larvae of Brugia pahangi in vitro at 50 p.p.m. but had no effect on microfilariae at 1 × 104 p.p.m. No larvae developed in infected mosquitoes fed 1% stibocaptate in 10% sucrose. It was neither micro-nor macrofilaricidal in neither jirds or cats but did affect embryogenesis.

Only five of the eight species assigned to the genus Paracooperia are considered valid and are redescribed. P. petrowi Memmedov, 1961 and P. indiana Ali and Deshpande, 1970 are considered synonyms of P. nodulosa (Schwartz, 1928) Travassos, 1937 and the synonymy of P. matoffi Le Roux, 1950 with P. nodulosa is confirmed. A key to the species of the genus is given and their hosts and geographical localities are listed.

The life cycle of Genarchopsis goppo a hemiurid trematode found in the stomach of Channa punctata has been worked out in detail. The egg contains a fully developed miracidium at the time of liberation. The miracidium contains a ciliated covering, a long apical gland and a crown of spines at the anterior end. The snail Amnicola travancorica acts as the first intermediate host inside which the miracidium passes through sporocyst and redial generations. The cercaria is of cystophorous type and is identical to Cercariae Indicae Sewell XXXV. Metacercaria occurs in the ostracods Stenocypris malcolmsoni and Eucyoris capensis. The fish Aplocheilus panchax serves as the paratenic host. The entire developmental cycle from egg to egg producing adult takes 3 months.

Two new genera, Gedoelstascarisand Ortleppascaris, are proposed for species of ascaridoid nematodes occurring in crocodilians and previously included in Dujardinascaris. Species included in Gedoelstascaris are vandenbrandeni Baylis, 1929 as type species and australiensis Baylis, 1931 (= salomonis Kreis, 1940). These species occur in Crocodylus spp. in Africa and Australia respectively and are characterised by lips with a rostral plate, without interlocking processes or dentigerous ridges, with well-developed interlabia, lobulated ventriculus, and excretory pore in front of the nerve ring. Species included in Ortleppascaris are: nigra Gedoelst, 1916 (= tasmani Ortlepp, 1932) as type species; alata Baylis, 1947; antipini Mozgovoy, 1950. These species occur in Crocodylus, Caiman and Alligator and are characterized by flat lips with alate margins, without anterior rostral plate, interlocking processes or dentigerous ridges, with weakly developed interlabia, by an irregular-shaped ventriculus, excretory pore behind or between the subventral lips, and by the presence of lateral alae or cuticular thickenings in the oesophageal region. The significance of this proposal is discussed in relation to the radiation and dispersal of ascaridoids of crocodilians.