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The relationships that now occur between ixodid ticks and agents of salmonelloses have been analysed. The paper presents the material on the spontaneous infection of ixodids, experimental data on the preservation of salmonellae in these ticks, their interaction and a mechanism of the agents transmission to warmblooded animals during bloodsucking of the parasites. On the basis of the observations conducted it was inferred that the relations between ixodid ticks and salmonellae are young from the evolutionary point of view.

The fleas of X. cheopis and C. tesquorum were found to be capable of laying eggs during the whole physiological active period without recurrent fertilization. The recurrent mating and fertilization occur in these species of fleas independently of their age and favour the rise in the abundance of their progeny.

In the valley of the Enisei (140 km from the town of Abakan up to the river) C. sinanoensis and C. sanguisuga are mass bloodsuckers while C. chiopterus and C. filicinus occur in small number. Data on the age composition of attacking females confirm the autogeny of C. filicinus and suggest the presence of autogeny in C. chiopterus. C. sinanoensis and C. sanguisuga can have two generations during the period of their activity. The emergence of the 1st generation takes place in the IInd—IIIrd decade of June, the emergence of the 2nd generation — at the beginning of August. The 2nd generation is so small, as a rule, that its appearance does not practically affect the abundance of attacking females. C. sanguisuga is less sensitive to light and attacks at a somewhat higher temperature as compared to C. sinanoensis. As a result, a morning peak of abundance of C. sanguisuga takes place in 1—2 hours after the peak of abundance of C. sinanoensis while the evening peak is 1—2 hours prior to it. The daily period of activity of C. sanguisuga is usually longer than that of C. sinanoensis.

Three new species of black flies of the genus Schoenbaueria are described which differ morphologically from other species of this genus. The new species were found in drying up brooks that also differs them from the species of the genus Schoenbaueria which develop mainly in large rivers. Material was collected in the Komsomolsk and Furmanov regions of the Ivanovo district.

It was established that the fecundity of females of different generations of C. p. punctatus, which are at the 1st gonotrophic cycle, is unequal. There was noted a decrease of the per cent of realisation of potential fecundity in females of the summer-autumn generation. The dependence of the virtual fecundity on the day length and temperature was studied. The differences in ther effect of these factors on the fecundity of females of the spring-summer and summer-autumn generations were found.

The conditions of the increase in the virulence of toxoplasms lines of the Czech low-virulent strain obtained by means of the infection of mice or chicken embryos with one cyst washed three times in physiological solution were investigated. It has been shown that all the 12 were potentially virulent since in the process of frequent (in each 7 days) passage through sensitive animals (bredless mice) they increased their virulence. The lines of toxoplasms passed only one time through chicken embryos increased their virulence quicker (1 to 10 passages) than lines passed only through mice (18 to 22 passages). At the simultaneous passing of toxoplasms of the same line through sensitive animals (bredless mice) and through more resistant ones [mice of lines AKR and BALB/c] toxoplasms increased their virulence during the 4th passage and did not change it up to the 25th passage, respectively.

Adult white rats were immunized by numerous subcutaneous injections of antigenes obtained from the cultures of В. coli and B. suis. After the rats were sensibilized they were infected with cultural forms of Balantidium. 75% of infected rats were found to have ciliates in the lumen of the large intestine. In the tissues of the intestinal wall up to the muscular layer there were observed certain pathomorphological changes such as hyperemy, oedema, haemorrhagia and ulcers. By means of the macrophaga migration test it was established that in rats during their immunization and following infection appear lymphocytes which are sensibilized in relation to the balantidial antigene that points to the formation of slow allergy in their organisms.

The cercaria of D. commutatum from the mollusk Radix ovata is described. Data on the biology and development of the cercaria up to the metacercarial stage are given. Gercariae of D. commutatum differ from all known species of the genus Diplostomum by a characteristic cuticular armament.

Experiments were conducted on the duration of life in sea water of three species of cystophorous cercariae from the Barents sea. The expenditure of reserve nutritive substances (glycogene) in the process of the vital activity of cercariae was followed. The life duration of cystophorous cercariae is considerably longer than that cited in literature for other groups of cercariae that is associated with their morphological and biological peculiarities.

In the biocoenosis of the Lake Tengiz (Central Kazakhstan) Eucypris inflata (0.3— 11%) was found to be spontaneously infected with the larvae of cestodes-hymenolepidids (6 species) and dilepidids (1 species). The nesting flamingos and moulting grebes from the same water body were also infected to a great extent with these cestodes. Figures and morphological description of cysticercoids (7 species) and scolex of mature cestodes of Parabiglandatrium phoenicopteri are given.

The formation of cysticercoids of the diplocyst type in three species of cestodes of the genus Aploparaksis: A. bulbocirrus Deblock et Rausch, 1968, A. furcigera (Rud., 1819) and A. groenlandica (Krabbe, 1869) at the experimental infection of oligochaetes (Lumbriculus sp.) is described. The development of diplocysts is characterized by two invaginations. The first invagination occurs at an early developmental stage when non-differentiated anterior part of the larval body submerges into the external cyst which is formed by the walls of the primary cavity displaced toward the hind end. The second invagination of the fully formed scolex and neck into the cavity of the internal cyst completes the formation of the diplocysts.

The crossing of stem eelworms of onion and red clover with these from Cirsium setosum and Taraxacum officinale resulted in the fertilization of females, egglaying arid embriogenesis. However, the hybrid eggs died, as a rule. Only in one experiment a large population developed up to F₅ but few hybrids survived to F₁₀. The studied stem eelworms of weeds are genetically non-compatible with Ditylenchus dipsaci of onion and red clover and are distinct species.

The fine structure of the brain and ventral nerve cord ganglia neurons has been studied in two subspecies of Chaetogaster lymnaei, one of them being a commensal and the other the kidney endoparasite. The nerve cells of parasitic forms are characterised by the presence of a whole set of structural simplifications. These are the poorer development of endoplasmic reticulum, the greater number of free ribosomes in the cell and the less number of mitochondria with certain alternations in the ultrastructure. The given features are suggested as criteria when studying the influence of parasitic mode of life upon the ultrastructural organization of the cells.

Eight year observations on the autogeny of С. p. molestus have shown that the per cent of autogenous females decreased from 87% (1968) to 25.6% (1976). The population of C. p. molestus from basement apartments of Leningrad can be expected to receive a replenishment from free-living C. pipiens.

The pupa of Toxorhynchites christophi Portschinsky is first described from the territory of the USSR.

The infection of larvae of Culex pipiens molestus, C. vagans and C. tritaeniorhynchus (the vector of the virus of Japanese encephalitis) with the entomopathogenic fungus Coelomomyces iliensis from Kazakhstan was carried out in the Primorje Territory in 1973 — 1974. At the infection of larvae of C. tritaeniorhynchus with the suspension of infected larvae the mortality was recorded only from 60% of individuals, while at the infection with a content of sporangia — from 36.6% of larvae. Somewhat less mortality (27.5%) was observed among larvae of C. pipiens molestus and C. pipiens. In control the mortali larvae did not exceed 5%.

An operation is described on the bringing out of the fistula from the blind appendage of chicks. It is reported that at hybridization of intraspecies strains of E. tenella with equal virulent properties the resulting virulence of coccidians increases 2.5—3 times.

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