title: [Reaction of Philophthalmus rhionica (Trematoda, Philophthalmidae miracidia to light].
abstract: 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 thepopulation. 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 the "+" 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.
mesh_terms: D000375:Aging; D000818:Animals; D004307:Dose-Response Relationship, Radiation; D007814:Larva / Q000528:radiation effects; D008027:Light; D009068:Movement / Q000528:radiation effects; D010775:Photic Stimulation; D014200:Trematoda / Q000528:radiation effects*
vernacular_title: Reaktsiia miratsidiev Philophthalmus rhionica (Trematoda, Philophthalmidae) na svet.