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At present still is lacking the general theory capable to explain the essence of factors determining the nature of relationships between the parasitic organisms and higher plants. This is associated with the crisis of the dominant theoretical system which suggests that plants possess active protective reactions to definite species and races of parasites having developed in the process of the evolution. Heuristic analysis of various conceptions and hypotheses has shown that the general theory of parasite resistance of plants can be based only on the ecological conception of parasitism and Y. P. Efroimson's theory of uncomplete medium.

A new six-graded scale is suggested instead of five-graded one proposed earlier (Kunitskaya, 1960). Analysis of the reproduction and age composition of the natural population of X. gerbilli with a use of the suggested scale enabled the authors to find out regularities in the reproduction, senescence and change of generations of these insects in South Pribalkhashje. It was established that one complete, one incomplete and possibly third partial generation develop in this region for a year.

Metacnephia pamiriensis Petrova, sp. n. in its genitalia is similar with M. pallipes. It differs in the number (16 rather than 30—60) and branching (arranged in three bundles) of respiratory threads and a peculiar structure of pupal cocoon. Diploid number of chromosomes is 6 (n=3). Chromosomes are submetacentrical. The peculiarities of polytenic chromosomes are described and results of karyological comparison with M. pallipes given.

For 6 years 16 species of the genus Aedes were recorded from the territory of Leningrad. To judge by the per cent ratio between mosquitoes and their larvae, such species as A. caspius dorsalis and A. flavescens suck blood of man unwillingly and A. cantans and A. cinereus attack man in general. The abundance of Aedes population within the territory of Leningrad was estimated on the number of pupae per 1 m² in various types of water bodies for the whole reproduction season by means of multiplication of the number of pupae per 1 m² by the whole area where aquatic stages of mosquitoes were observed.

Females of I. persulcatus and D. silvarum are very sensitive to baytex, the value of LD₅₀ for both species are similar. The development of injury after exposure to baytex proceeds very quickly and the subsequent stages of injury development correspond to those caused by DDT (Uspensky and Levikov, 1974). The overcoming of baytex poisoning during the sucking of the host's blood is possible only at the initial stage of the injury. The simultaneous feeding on the same rabbit of ticks treated with baytex and control ones has shown a system effect of baytex on the second group of ticks.

I. pavlovskyi is absent from the eastern macroslope of Sykhote—Alin, rare in the central part of the ridge and is quite common in western Sykhote—Alin where it accounts for no more than 10% of total collections with I. persulcatus. An average density of ticks in forests of western Sykhote—Alin is 50 to 80 active adults per hectare, maximum density — 150 specimens. Larvae feed on various small mammals and birds, nymphs — on birds and mammals larger than Sibirian chipmunk. Adults feed on hedgehogs, hares and birds, preferrence being given to hazel hens.

The paper presents the materials on the identification and study of the developmental forms and morphology of B. colchica and P. bigeminum in eggs of Hyalomma anatolicum. The description of developmental forms of В. colchica in eggs of Boophilus calcaratus is given for the first time. P. bigeminum and P. beliceri were detected in eggs of B. calcaratus and H. anatolicum from the first day of egg production up to the emergence of larvae while B. colchica was found beginning from the 4th—5th day of egg production up to the 5th—7th day before larvae emergence. The invasion rate of eggs of B. colchica is considerably smaller than that of B. bigeminum and P. beliceri. In piroplasmids and babesians there were observed sigar—like, roundish, amoeba-, pear-, rod-shaped and oval forms. Some individuals of piroplasmids had projections of cytoplasm of different size. Individuals of B. colchica are smaller than those of P. bigeminum and P. beliceri that enables an easy differentiation of babesians from piroplasmids.

Описывается морфология копеподитной стадии паразитического веслоногого рачка Dichelesthium oblongum, найденной на коже белуги в северной части Каспийского моря.

Studies were undertaken of the fine structure of microsporidian, schizont, sporoblast and spore of Nosema diplostomi Schigina et Grobov, 1972 parasitic in metacercariae of fish eyes. The spore wall with outer membrane of the nuclear substance, polar filament, pola-roplast, sporoplasm and rough endoplasmic reticulum are described. The diameter of a partially ejected filament is larger than the polar filament inside the spore.

Mortality of pelyad (Coregonus peled) caused by Tetraonchus alaskensis took place in winter 1973 in the Voikara and Syn rivers (the Ural tributaries of the Lower Ob) during anadromous and catadromoiis migrations. The highest infection rate was observed in older fishes. Up to 2330 specimens of the parasite were recorded from the gills of one pelyad. A low infection rate with T. alaskensis was recorded from Coregonus nasus, C. lavaretus pidgian and Stenodus. The mortality coincided with the period of the greatest abundance of the Ob pelyard stock.

The anatomy of the nervous apparatus of Triaenophorus nodulosus at all stages of its life cycle was studied by means of Zherebtsov's hystochemical method. Judging by the cholinesterase activity the mass of nerve cells is situated in the oncospheres of the coraci-dium. At the procercoid stage the ortogonal nervous system arises with three pairs of the longitudinal nervous trunk. In plerocercoids the number of longitudinal trunks increases up to 7 pairs, the rough nervous plexus and inner plexus develop too. In mature cestodes only secondary changes take place associated with the development of the genital system. Both in larvae and adults all longitudinal trunks are situated at the same level, on the border of the cortical and medullary parenchyma, and only the inner nervous plexus first described by the authors from cestodes passes through the medullary parenchyma. The arrangement of all elements of the nervous apparatus at the same level corresponds from the authors point of view to the most primitive state of the nervous system in the order Pseudophyllidea.

Experimental infection of roach with cercariae of Diplostomum spathaceum has shown that the penetration of larvae into the eyeball proceeds in hematogenous way. Metacercariae are localized in the cortical layer of the crystalline lens thus causing destructive changes of its fibres and the dimness of the lens. The appearence of the dimness of the lens carries out without any apparent reactive changes in its epithelium. This enables to distinguish a parasitic cataract from all other varieties of cataracts.

In the lower Amur (the Khabarovsk region) 25 females, 20 males and 3 nymphs of Ixodes lividus were collected from 15 inhabited nests of Riparia riparia.

The genus Lacertacarus g. n. is close to Neotrombicula differing from the latter in lanceolate dorsal setae, wide shield and other characters. Lacertacarus includes two new species, L. similis sp. n. and L. latus sp. n., and Trombicula callosa Schluger, 1966 described earlier. Descriptions and key to species of the genus are given. Larvae were collected from lizards in the Krasnodar territory, Georgia.

The work was conducted with a typical strain of the plague agent, which is virulent to white mice and little virulent to guinea pigs (subcutaneous infection), and with C. fasciatus. The fleas of this species can be infected, form the block of proventriculus within 4 to 35 days, transmit the agent during bloodsucking to healthy animals and cause the death both white mice and guinea pigs.

A new species of the microsporidia Th. volgensis is described. The species was found in larvae of four species of bloodsucking mosquitoes from Middle Povolzhje.

A new species of microsporidians, Thelohania assovi sp. n., was found in population of larvae of Odagmia sp. inhabiting mountain rivers of Tien-Shan and south-eastern Kazakhstan. The infection of larvae with this species varies from single individuals to 18—20% while pupae are infected only with single specimens. The species differs from all known members of this genus in a number of characters. Size of 50 measured spores varied from 4.4—7.0x2.5—3.8 in live specimens to 3.8—6.4X2.3—3.8 mem in fixed ones. The parasite causes patho-morphological changes in injured tissues.

206 birds of 11 species were examined. The variational and statistical analysis has shown the dependence of the infection rate of birds and the helminth fauna diversity on the dryness or degree of humidity of biotopes, on the «specific weight» of animals-invaders in the food of birds and on the accumulation of some helminths in birds, definitive hosts, as compared to invaders.

11 species of monogeneans were found on Schizotorax intermedius from the Kafirnigan river during investigations conducted in 1972. Their seasonal dynamics has a typical biapical curve of the parasites number.

In Upper Priamurje domestic and wild mammals were examined for the infection with Clonorchis sinensis. It was found that in the south—eastern regions of the Amur district 45.8% of cats were infected with Clonorchis sinensis. In wild carnivorous animals this desease is very rare. Among 109 examined raccoon dogs the infection with Clonorchis sinensis was recorded only from two animals.

Summary is absent.