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A short critical revew of modern literature on tick's pheromones is given. Correlation between the type of pheromone system and biological features of the main systematic groups of ticks is proposed.

Two types of granulosecreting alveoles were found in salivary glands of hungry females by means of electron microscopy of ultrafine sections. Alveoles of the IInd type occur in the anterior helf of the gland. They are not numerous and consist of three types of secretory cells (А, В, С) surrounding the inneralveolar cavity. The secretory cells are separated from each other and from the basal membrane by the strands of the epithelial cells P. Three types of spherical inclusions were found in the secretory cells. They differ in size, electron density and intensity of staining of half-fine sections with toluidin blue. The apical cytoplasmatic membrane of secretory cells bears numerous microvilli. Alveoles of the IIIrd type, which constitute the main mass of the gland tissue, have a narrow slit-like inneralveolar cavity. The basal part of the alveole is formed by 3—4 large cells filled with large spherical electron-transparent vacuoles of the secretion. The apical part of the alveole is occupied by 9 to 11 cells E, whose cytoplasm is filled with numerous flat cisternae of granular endoplasmatic reticulum and small and medium secretory vacuoles of different electron density. Alveoles of the IInd andIIIrd type of I. persulcatus are not identical with those of Hyalomma asiaticum, Boophilus microplus and other members of the subfamily Amblyomminae.

A mineral components concentration in the haemolymph of the Ilnd- and Illrd-stage larvae of Oedemagena tarandi depends on the physiological state of parasites. Metabolism of mineral components is most intensive in a young actively growing organism and during moulting. The moulting is characterized by the decrease in the concentration of inorganic phosphorus and potassium and by the increase of calcium, magnesium and natrium.

A series of laboratory experiments has shown that the feeding of X. cheopis infected with В. pestis on great gerbils exposed to anticoagulants, derivatives of indandion (diphenacin, phentolacin) results in the inhibition of protein formation in vectors. Due to supposed antiepizootic effect of these zoocides they are suggested to be tested in natural nidi of plague.

The omentum of 8 white mice was examined 24—96 hours after the intraperitoneal infection. Endozoites are capable of intensive intrusion not only into phagocytizing cells (hystocytes, peritoneal macrophages) but also into the cells which are not phagocytes (mesothelium). Just after the intrusion metabolism of the host-cell intensifies and in it are formed special structures which facilitate metabolic processes between the cell and the parasite (microvilli on the membrane of the parasitophore vacuole). At the final stage of the interaction with the cell endozoites cause the lysis of the membrane of the parasitophore vacuole that facilitates their transition into new cells. The ability to intrude into the cells, which are not phagocytes, and to cause the lysis of parasitophore vacuole is a factor of pathogenicity of virulent strains of toxoplasms which determines the generalized character of the infection caused by them.

Broiler 7-week old chicks were infected with E. tenella (150 000 oocysts). The contents of aminoacids of muscular tissues of femur and liver as well as combined aminoacids of femoral muscles were investigated. It has been established that the total amount of aminoacids of muscular tissues increases on account of free aminoacids while the contents of combined aminoacids decreases. In the liver of infected chicks there was observed an increase of alanine and a decrease of histidine, arginine and of total quantity of non-substituted aminoacids. Coccidial infection causes pathological changes in the organism of birds thus reducing their food value.

The paper concerns the toxonomic position of the species Diplozoon bychowskyi, D. ctenopharyngodoni and D. strelkowi. As far as there are no serious morphological differences between them the first two species are reduced to synonyms of D. strelkowi. Despite the great similarity between D. diplodiscus and D. strelkowi some characters do not allow to consider them synonyms. On the basis of new data the descriptions of D. diplodiscus and D. strelkowi are given.

The consecutive development of the genital organs in proglottides of the mature strobile of Passerilepis crenata was studied. The organs of the male and female genital systems, excluding testes and efferent ductules, are laid as a common genital anlage, which later become subdivided into three departments. On the basis of the degree of development of the genital organs zonation of the worm's strobile has been specified.

The light response of miracidia was studied by means of several original methodics. The heterogeneity in the character of light response between various larvae of the same age population was determined in the course of experiments. It was shown that a part of miracidia possesses the strict positive phototaxis. Moreover, in their movement to the light the larvae seem to orientate themselves on the light intensity gradient. Not all the miracidia possess the positive phototaxis ("+" miracidia). Some of them ("—" miracidia) leave for the dark side of camera under the influence of direct ray of light. There are also larvae indifferent to the light conditions in the population. They can move in different directions in spite of the light ray direction ("0" miracidia). The number of "+", "—' and "0" miracidia in the population is inconstant. The number of the negative phototactic larvae grows with age and respectively the number of "+" miracidia decreases. It is obvious that "+" miracidia can transform into "0" or "—" forms, while there is no opposite transformation. The reasons of differences in the movement character of "+" and "—" miracidia are under discussion.

The species composition of tabanid flies from the southeastern part of the Khanty-Mansijsk territory (the river Vakh basin) was studied. 15 species belonging to 4 genera were found as follows: Chrysops, Atylotus, Haematopota, Hybomitra. The duration of flight, abundance of tabanid flies and the periods of their damaging activities were established.

22 species of fleas have been found on five species of jerboa in southern Pribalkhashje. Of them 8 species are parasites of jerboa, 13 — of gerbils and one — of birds. Most abundant are three species of fleas of jerboa: M. lenis, M. eucta and O. volgensis. Of gerbils' fleas representatives of the genus Xenopsylla were dominant on jerboa. The greatest indices of abundance have been reported for A. severtzovi, A. elator, A. acontion. The gerbils' fleas are more abundant on D. sagitta than on the other species.

A new species of myxosporidians, Myxobolus musseliusae sp. n., from gill filaments of the young of Cyprinus carpio from ponds of the Angelinsk fishfarm, Krasnodar territory, is described.

The break in sporogony of Th. fibrata, parasitic in larvae of O. ornata, is described. The break is caused by low temperatures of water body in winter when preimaginal stages of black flies develop.

On the basis of the material collected in the Red Sea and the Indian Ocean four new species of trematodes are described: Bucephalopsis pseni sp. n., Diploproctodaeum chelonodoni sp. n., Bucephalus neoscombropsi sp. n., Phyllodistomum sobolevi sp. n. Anatomical and morphological characteristics of the above species as well as original figures of the trematodes are given, their taxonomic position is discussed.

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