Phytophthora citricola constituted about 70% of all Phytophthora isolates recovered from rhododendron leaves used as baits for detection of that group of organisms in water. The species was found in 4 rivers, 2 hardy nursery water reservoirs and nursery drainage canal from May to October, 2006. Analysis of spots’ number on rhododendron leaf baits as a measure of P. citricola density showed that place of holding baits had a significant influence on the species occurrence. Significantly more spots, especially in July survey, were observed on baits held in Skierniewka and Zwierzynka rivers swimming through agricultural and forest area than in Ner, the river of horticultural area. Significantly more spots/rhododendron leaves were observed when they were held in rivers downstream of nursery and in the middle of hardy nursery borders. In nursery water containers and drainage canal higher Phytophthora density was recorded in August than in other periods of surveying. Using water from reservoir for sprinkling of Picea omorika nursery trees caused the development of tip blight and from diseased twigs P. citricola was isolated.

Canal connecting Elbląg with Ostróda was built in the XIX century to transport corn to the port of Elbląg. Due to economic and political changes it never played its economic function. Now it is a tourist attraction. The canal is thus of some tourist value which is difficult to assess. Tourist value of the Elbląg Canal was assessed with the travel cost method (TCM) within the study carried out in 2003. The study allowed for estimating the object’s value based on its usefulness expressed by inclination to payment. Three groups of users were distinguished when analysing the demand for recreational canal’s services: tourists using ships of the Elbląg–Ostróda Navigation Company, individual sailors and anglers. Total tourist value of the canal calculated as NPV of the annual value of canal’s services depends on adopted interest rate. At a rate of 3.2% the value is 328 thous. PLN (73.9 thous. euro), at a rate of 4% – 282 thous. PLN (63.5 thous. euro), while at 8% interest rate it decreases to 160 thous. PLN (36.0 thous. euro).

The abducens nerve is characterized by a long intracranial course and complex topographical relationships. Anatomical knowledge may help to understand both the etiology and clinical symptoms of abducens nerve palsy. Typically, the single trunk of the abducens nerve travels on both sides. However, occasionally different variants of unilateral or bilateral duplications of the abducens nerve may be observed. Th e presented paper is a detailed anatomical description of bilateral duplication of the abducens nerve, with atypical appearance of the nerve in the cavernous sinus and normal distribution within the lateral rectus muscle on both sides of one cadaver. On the right side both trunks of the abducens nerve fused within the subarachnoid space and pierced the dura mater together. On the left side both trunks of the duplicated abducens nerve pierced the dura mater separately, entered the petrous apex separately and fused just below the petrosphenoidal ligament. Within the cavernous sinus the nerve divided once again into two filaments, which reunited into one trunk aft er crossing the horizontal segment of the intracavernous part of internal carotid artery. Th e orbital segments of the abducens nerve showed a typical course on both sides. Duplication of the abducens nerve is anatomical variation which should be taken into account during diagnostic and surgical procedures performed within the petroclival region and cavernous sinus.

For the last few decades there have been reports not only of the occurrence of new invasive species of European water-courses, but also their increasing expansion. One of such species is the Amur sleeper (Perccottus glenii). The present work contains assessment of age and length distribution, condition as well as growth rate and analysis of the parasite fauna of theAmur sleeper from the waters of the Vistula River tributary in its middle course (the Habdziński Canal). During the catch performed in 2017 and 2019, the total of 177 Amur sleepers were recorded in the studied watercourse and a statistically significant sex structure disproportion was observed. Among the specimens caught in 2017 dominant were fishes with lengths of 50.1–60.1 mm whereas in 2019 the majority of the Amur sleeper specimens measured 30.1–50.0 mm.Six age groups were recorded among the caught fish with a clear prevalence of specimens aged 1+ (70.06%). The most frequently recorded parasite of P. glenii was non-quantifiable Trichodina rostrata ciliate for which the Amur sleeper from the Polish waters appeared to be a new host. Moreover, the presence of an acanthocephalan Acanthocephalus lucii, not recorded in Poland in this host before, was observed in the chyme. Also, accidental presence of larvae of the Opisthioglyphe ranae tre-madote, which is a parasite typical of amphibians, was also recorded. Despite unfavourable habitat conditions and in-creased volumes of biogenic substances in the waters of the Habdziński Canal, the Amur sleeper found convenient condi-tions to reside in this small watercourse.

O b j e c t i v e s: To identify tooth diseases as potential causative factors in the development of maxillary sinus lesions, with the aid of clinical examination combined with Cone Beam Computed Tomography (CBCT), in the patients with persistent sinus-like ailments, unresponsive to routine treatment offered by otolaryngologists.

M a t e r i a l s a n d M e t h o d s: In 44 patients with suspected odontogenic maxillary sinusitis, a dental examination with tooth vitality test was carried out, in conjunction with CBCT. The study involved 29 women and 15 men (age range 19–69 years, mean age 43 (SD = 13.9) years).

R e s u l t s: In 15 (34.1%) patients the odontogenic lesions were encountered in maxillary sinuses. A total of 33 causative teeth were identified, of which 13 (39%) were after root canal treatment (RCT). Only one of the teeth had a properly reconstructed crown, and only one tooth had the root canals properly filled-in. Most frequently, the lesions in the sinuses were attributed to the inflammation of periapical tissues; the first molar having been established as the most common causative tooth.

C o n c l u s i o n s: A detailed dental examination, pursued in conjunction with CBCT analysis, allow to diagnose odontogenic maxillary lesions. The incidence of long-term ailments originating in the maxillary sinuses should prompt a detailed assessment of the teeth, especially those after RCT.