LIGHT AND MOVEMENT 



51 



II 



Fig. 23. — Klinotaxis in a Crawling Organism. 



The maggot is photo-negative and crawls away from the hght (below). 

 From the initial position, 1, it contracts into 2, elongates into 3 and contracts 

 again into 4, each time swinging its head across to one or other side. So long as 

 the sides of the head are equally illuminated its path is straight. At 3, the 

 lower light is switched off and the side light switched on ; the organism 

 immediately swings violently into position .5. Thereafter it contracts to 6, and, 

 having swaing in the opposite direction to 7, again receives preferential illu- 

 mination on the side. It therefore swings again violently to 8 and, having 

 contracted to 9, proceeds again, as before, directly away from the light (10) 

 (after Mast, 1911). 



away from the light (Fig. 23). If a hght is persistently flashed on the 

 same side on each deviation of the head, a circus movement is produced, 

 and if two directed lights are simultaneously employed the animal 

 crawls away at a direction half-way between the two beams if they are 

 equal, or proportionately more nearly in line with the brighter beam if 

 they are unequal (Patten, 1914). 



Bancroft. J. exp. ZooL, 15, 383 (1913). 

 Buder. Jb. wiss. Bot., 58, 105 (1917). 

 Ellsworth. Ann. entom. Soc. Amer., 26, 



203 (1933). 

 Herms. J. exp. ZooL, 10, 167 (1911). 

 Holmes. J. comp. Neurol., 15, 98, 305 



(1905). 

 Jennings. Publ. Carnegie Inst., Wash., 



No. 16, 256 (1904). 

 Loeb. Studies in General Physiology, 



Chicago (1905). 

 The Dynamics of Living Matter, N.Y. 



(1906). 

 Forces, Movement s,Tropis7ns and Animal 



Conduct, Phila. (1918). 

 Mast. J. exp. Zool., 3, 359 (1906). 



Light and the Behavior of Organisms, 



N.Y. (1911). 

 Biol. Zbl., 34, 641 (1914). 

 Z. vergl. Physiol., 5, 730 (1927). 

 Biol. Rev., 13, 186 (1938). 

 Mast and Cover. Biol. Bull., 43, 203 



(1922). 

 Mast and Johnson. Z. vergl. PliysioL, 16, 



252 (1932). 

 Patten. J. exp. ZooL, 17, 213 (1914) ; 20, 



585 (1916). 

 Pouchet. Rev. mag. ZooL, 23, HO, 129, 



183, 225, 261, 312 (1872). 

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studien, Jena (1889). 

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