Identifier: journalofexperim31harr (find matches)
Title: The Journal of experimental zoology
Year: 1920 (1920s)
Authors: Harrison, Ross G. (Ross Granville), 1870-1959 Brooks, William Keith, 1848-1908 Wistar Institute of Anatomy and Biology American Society of Zoologists
Subjects: Zoology
Publisher: (New York, etc.) Wiley-Liss (etc.)
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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ough the water of the aquariumin which the animals were placed. The stand on which theaquarium rested was of the same height as a microscope stage,so that in carefully observing the path of an animal a microscopewith a camera-lucida attachment could be substituted for thestand. When a microscope with a camera lucida was used, asmall drawing-board was placed beside the microscope (fig. 1, C),and illuminated by a small light which was so secured that nolight could strike the animals under observation. In tracingthe paths of specimens with a microscope and camera lucida, itwas found advisable to use very low magnifications. The use ofvery low objectives (; inch) and eyepieces not only permittedthe observation of specimens over a greater range, but it also REACTIONS TO LIGHT IN PLANARIA MACULATA 67 obviated the necessity of providing any vertical illumination forthe microscope, the horizontal beam of light used in the experi-ment being quite sufficient. Had it been necessary to use verti-
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Fig. 1 Diagram of apparatus for observing reactions of Planaria to a hori-zontal beam of light. A, aquarium; B, lamp boxes which can be moved towardand away from the aquarium; C, position of drawing-board when camera-lucidais used; K, double-throw, double-pole knife switch; L, 125-Watt gas-filled lamp; *S,screen; T, wires to wall tap; W, distilled water. cal illumination, it might have introduced an extraneous factorin these experiments. The aquaria in which the animals were observed were rectan-gular. They were made of plate glass and Kotinsky cement. 68 W. H. TALIAFERRO The use of such aquaria is essential, as it is practically impossibleto control the path of the rays of light after being refracted bythe irregular curved sides of the ordinary aquarium. All obser-vations were made in a dark room and, as far as possible, allapparatus was painted dull black so as not to reflect light. The apparatus used for measuring the rate of movement inspecimens was essentially like that of Walter

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