LIGHT AND MOVEMENT 47 



migrate downwards to starvation if illuminated from below (Loeb, 1918 ; 

 Lammert, 1925 ; v. Buddenbrock, 1930) ; while, provided the stimulating light 

 is sufficiently bright, the negative phototaxis of the larva of the bluebottle, 

 Calliphora, will induce it to approach a source of ammonia of lethal concentra- 

 tion (Hurst, 1953). 



Andrews. Physiol. ZooL, 25, 240 (1952). Claus, Grobben and Kiihn'a Lhb. der 



Armstrong. Anat. Rec, 105, 515 (1949). ZooL, Berlin (1932). 



Bolwig. Brit. J. anim. Behav., 2, 144 Lammert. Z. vergl. Physiol., 3, 225 



(1954). (1925). 



V. Buddenbrock. Z. vergl. Physiol., 13, Loeb. Forced Moveinents, Tropisma and 



164 (1930). Animal Conduct, Phila. (1918). 



Clark. J. exp. ZooL, 51, 37 (1928) ; 58, 31 Lowe. J. Anim. EcoL, 21, 275 (1952). 



(1931) ; 66, 311 (1933). Lynch. JSioZ. JSmZZ., 97, 302 (1949). 



Fox. Proc. Carnb. philos. Soc. biol. Sci., Mast. Light and the Behavior of Organisms, 



1,219(1925). N.Y. (1911). 



Fraenkel. Z. vergl. Physiol., 5, 585 (1927). Biol. Rev., 13, 186 (1938). 



Goustard. C. R. Acad. Sci. (Paris), 227, Mast and Pusch. Biol. Bull., 46, 55 



785 (1948) ; 228, 864 (1949). (1924). 



C. R. Soc. Biol. (Paris), 144, 485 (1950). Matthews. J. exp. BioL, 30, 268 (1953). 



Grave. J. Morph. Physiol., 4i9, 355 {1930). Medioni. C. R. Soc. Biol. (Paris), 148, 



Gunn, Kennedy and Pielou. Nature 2071 (1954). 



(Lond.), 140, 1064 (1937). Payne. Biol. Bull., 18, 188 (1910) ; 21, 



Harper. Biol. Bull, 10, 17 (1905). 297 (1911). 



Henke. Z. vergl. Physiol., IZ, 53'^ (\930). Richard. C. R. Acad. Sci. (Paris), 226, 



Hurst. AWwre (Lond.), 171, 1120 (1953). 356(1948). 



Jack and Williams. Bull. ent. Res., 28, Ruppell and Schein. Vogelzug., 12, 49 



499 (1937). (1941). 



Kiihn. Die Orieyitierung der Tiere im Viaud. C. R. Soc. Biol. (Paris), 143, 534 



iJaum, Jena (1919). (1949). 



Bethea Hb. norm. path. Physiol., 12 (I), Viaud and Medioni. C. R. Soc. Biol. 



17 (1929). (Paris), 143, 1221 (1949). 



The Types of Phototactic Response 



We shall now proceed to exemplify the various types of phototactic 

 responses ; but, as we have just seen, it is to be remembered that 

 animals usually orientate themselves in more than one way depending 

 on the circumstances prevailing. It is less correct to say, for example, 

 that an animal is telotactic than that it may exhibit a telotactic 

 reaction. Thus, as we shall see, some ciliated Protozoa or worms show 

 an undifferentiated photokinetic response with one stimulus and a 

 klinotactic or tropotactic response with another, while in its complex 

 but very efficient mechanism of orientation, the honey-bee combines 

 tropotaxis, telotaxis and menotaxis with mnemotaxis. 



KLINOTAXIS 



The most primitive directed orientation to light is by klestotaxis 

 whereby turning movements, normally alternating regularly, are specific- 

 ally orientated with respect to the light. This is well exemplified in the 

 behaviour of flagellated or ciliated Protozoa or the maggot larvae of 

 certain common flies. Each of these shows a different type of response. 

 The Protozoa orientate themselves as a result of successive stimuli 

 falling on a photosensitive organ periodically exposed as they rotate 



