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In the cysts of S. fusiforrnis and S. gigantea parasites from oesophagi of buffaloes and sheep the increase in the deoxyribonuclease II activity during aging of cysts of both species has been established. It has been found that in all age groups of S. fusiforrnis cysts the activity of this enzim is greater than in the corresponding age groups of S. gigantea.

The relation between host cell (oocyte and muscular cell) and plasmodia of Myxosporidia Henneguya oviperda and Kudoa quadratum was studied by means of electron and light microscopy and cytochemistry. The absence of parasitiphorous vacuole and capsules of any kind around plasmodia has been established. The more rapid accumulation of yolk in infected oocyte has been demonstrated. The data on metabolism of Myxosporidia in question are discussed.

In oocytes of the Volga and Don sterlet (Acipenser ruthenus L.), 107 specimens of unicellular stages and 64 specimens of cleavage stages of Polypodium were studied with the light microscope. The entire embryonic development of this parasite occurs inside acipenserid oocytes. The stages of development of the parasite correspond to stages of the host's oogenesis. The embryonic development of Polypodium lasts several years and is probably the slowest among the coelenterates. Polypodium has the smallest eggs as compared with other representatives of the same animal phylum. The eggs of Polypodium develop without fertilization inside a nutritive cell, the trophamnion, which separates as early as at the II meiotic division of the oocyte. The cleavage is total and includes a long-lasting morula stage. Gastrulation occurs by morular delamination. The inversion of the germ layers is likely to take place at the same time. The blastomeres and the trophamnion have large nucleoli in their nuclei and actively synthesize RNA. The embryonic development of Polypodium displays some features typical of the class Hydrozoa.

Data were obtained proving the presence of the system of glucose active transport in E. rugosum. Transport kinetic characteristics were estimated and their dependence on the incubation temperature was shown. Heterogeneity of strobila with respect to transport processes was found.

A description of the consecutive stages of ripening of ovary cells of early fission and gastrulation of T. pisiformis and T. hydatigena, peculiar to the common type of fission of Cyclophyllidea is given. The fission has signs of double spiral fission which takes place in primitive Turbellaria. The primitiveness of early embryogenesis is reflected in early determination of macromeres, in the absence of strict regulation in the location of blastomeres, in the formation of blastula and unipolar gastrulation with the absence of morphological differentiation of ectoderm and mesenchyme.

Rediae and cercariae of Acanthoparyphium macracanthum sp. n. were found in the hepatopancreas of Batillaria cumingii (Gastropoda, Potamididae) inhabiting the muddy seashores of the Vostok Bay (Sea of Japan). Encysted metacercariae of the new species develop in the pelecypods Ruditapes philippinarum and Nuttallia olivacea living in the same habitat. These metacercariae were obtained under laboratory conditions after infection of Ruditapes and Protothaca euglypta by the cercariae from B. cumingii. The adults were found in the intestine of 48-day-old chickens 5 days after their feeding with tissues of infected Ruditapes. The morphology of the life cycle stages of the new species was examined.

The simple eye of the human louse consists of two apparatuses: dioptric and light sensitive. The dioptric apparatus contains only a biconvex lens, which represents local thickening of the cuticle. The eye lacks the cristal cone (Semper cells) and special pigment cells. The light sensitive part of the eye contains about 130 photoreceptor cells. Each photoreceptor has rhabdomere which consists of numerous microvilli. The pigment granules are located only in the photoreceptory cells.

The date of the beginning of mating behaviour in males and females, the rate of insemination and the increasing of bloodsucking activity of females were studied in natural environments. Over 80% of females mated on the 3-4th day after emergence; after fertilization their behaviour changed from looking for males for coupling to looking for ones for a prey. The male swarming began on the 5th day after emergence and simultaneously the appearance of inseminated females was observed. The places of mating of males and females were investigated. It was established that coupling took place in swarms with swarming males and out of swarms with freely flying males.

The paper considers diseases of marals and axis deer caused by warble flies as one of the factors affecting the deer-breeding productivity. Data on the infection rate of marals with larvae of Hypoderma diana and Pharynomyia picta and axis deer with H. diana are given.

A new species of Myxosporea, Sinuolinea sakinachanumae sp. n., is described and figured. The species was found in gall-bladder of Syngnathus nigrolineatus caspius Eichwald from the Caspian Sea.

A new species of furcocercariae from the freshwater mollusc Anisus kamtschaiicus (West.) found on Kamchatka is described.

The fauna of Myxosporea from Beryx splendens Lowe (Berycidae) from different parts of the Atlantic Ocean is described. 7 species of Myxosporea were found. Coccomyxa ovale, Ceratomyxa delicatula, Pseudalataspora beryxi are new species. Beryx splendens is a new host for Myxidium procerum and M. bajacalifornium. M. bajacalifornium was found in the Atlantic waters for the first time.

A description of a renicolid cercaria found in Prosobranch Neptunea borealis from the southeastern part of the Barentz Sea is given. On the basis of a detailed analysis of the morphology of the related forms the found cercaria is considered as a new species.

A comparative hystochemical study for the presence of reserve nutrients (glycogen, fat) in tissues, organs of parthenits (sporocysts, rediae) and larvae (miracidia, cercariae, adolescariae) of Fasciola hepatica from liver of sheep and cattle was carried out. The glycogen amount prevails at all developmental stages of Fasciola from sheep as compared to those from cattle. Fat was found in tissues and organs of parthenits and larvae of this trematode in equal amount. Its reserves are obviously smaller than those of glycogen.

To determine seasonal dynamics of abundance of Ixodes persulcatus P. Sch. by standard methods the ticks collected on flag were marked with a non-repeated group mark and returned into the registration route. As a result it was established that during the season of ticks' activity in the biotope of shrub meadows 26%, in the biotope of cluttered up glades 14.4% and in the biotope of aspen young forest 13.8% of marked ticks were repeatedly found. Of all considered factors affecting repeated occurrence of ixodids on a registration route their transfer by wild animals, which use this route in their movements, may play an important part.

A key for identification of species of the genus Phoretodagmia is given. Lectotype and paralectotypes of the species Ph. ephemerophila (Rubzov) are designated. The species-name obicumbensis Rubzov is considered as a junior synonym of the species-name ephemerophila (Rubzov).

A description of a new parasitic isopode Syscenus atlanticus n. sp. (Isopoda, Aegidae) from the Atlantic is given.

Summary is absent.