. The Journal of experimental zoology. Fig. 4 Camera-lucida drawing of the path of a Planarian, showing the rela-tion between changes in the direction of illumination and the direction of locomo-tion. C-E, path of specimen; R, point at which wandering reflex took 1 to 6 indicate successive directions of rays of light. Dotted lines extend-ing from the arrows 2 to 6 indicate the position of the planarian on its path whenthe direction of the rays was changed. 74 W. H. TALIAFERRO that the planaria practically always turned directly from thelight without trial movements. 1. Extraneous
. The Journal of experimental zoology. Fig. 4 Camera-lucida drawing of the path of a Planarian, showing the rela-tion between changes in the direction of illumination and the direction of locomo-tion. C-E, path of specimen; R, point at which wandering reflex took 1 to 6 indicate successive directions of rays of light. Dotted lines extend-ing from the arrows 2 to 6 indicate the position of the planarian on its path whenthe direction of the rays was changed. 74 W. H. TALIAFERRO that the planaria practically always turned directly from thelight without trial movements. 1. Extraneous reflexes during orientation. After a given speci-men is oriented and is proceeding away from the source of illum-ination there are a number of different motor activities that canbe noted. Two of these, although they do not seem to play any. Fig. 5 Diagram representing orientation to light in normal specimens andwandering reflex. The arrows x and y indicate the direction of the rays oflight. A, B, and C, indicate path of specimen. 1, 2, 3, 4, and 5, successive posi-tions of specimen; w, point of beginning of wandering reflex. When specimenreached position 2 the light y was intercepted and light x turned on. significant part in the normal process of orientation, will be de-scribed here because they later become of great interest in otherreactions to light. The first of these I have designated thewandering reflex. After an animal is oriented, it takes a fairlystraight course for a certain distance (1 to 4 cm.), then it beginsto wander toward the right or left. If the animal in this wander-ing turns far enough to allow the rays of light to enter the pig- REACTIONS TO LIGHT IN PLANARIA MACULATA 75 ment-cup of the eye, it suddenly reorients and again proceedsdirectly from the source of stimulation as represented in figure4, R.
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectzoology, bookyear1920
