60 



THE EYE IN EVOLUTION 



Silver-fish 



Mosquito 



Gonodactylus 



number of species by numerous observers.^ If the insect is illuminated 

 from in front, it steps forwards using all its legs ; if from the side, the 

 front legs on both sides step towards that side even if one eye only or 

 parts of the eye are functional (Fig. 34) ; and if the front leg on one 

 side is removed, on lateral illumination the front leg of the other side 

 is extended towards the light, pulling the animal round towards the 

 normal or, if necessary, the mutilated side so that it can orientate 

 nearly as precisely as a normal insect (Mast, 1923-24) (Figs. 35 and 36). 



scoTOTAXis (oKOTos, darkness) is a term sometimes employed to describe 

 the habit of some organisms, particularly insects, to travel towards a dark 

 object : thus insects such as the silver-fish, the caterpillar, the ant, the mosquito 

 and the louse ^ will travel towards a dark screen ; if such a screen and a light 

 are exposed, some will go directly away from the light (negative phototaxis) 

 and some towards the dark screen (scototaxis).^ The stomatopod, Oonodactylus, 

 which becomes more active in darkness, will always seek a dark shelter rather 

 than a bright object even althovigh it has to swim towards the light to get there 

 (Bolwig, 1954). It is jorobable, however, that in most cases such behaviour can 

 be included within the concept of negative telotaxis, althovigh occasionally the 

 form of a dark object may be important in the orientation. 



Alverdes. Z. wiss. ZooL, 137, 403 (1930). 

 Bauers. Z. vergl. Physiol., 34, 589 (1953). 

 Bolwig. Brit. J. anim. Behav., 2, 144 



(1954). 

 Buck. Physiol. ZooL, 10, 412 (1937). 

 v. Buddenbrock. Wiss. Meeresuntersuch. 



N. F. Abt. Helgoland, 15, 1 (1922). 

 v. Buddenbrock and Schulz. Zool. Jb. 



Abt. Zool. Physiol., 52, 513 (1933). 

 Carpenter. J. co7np. Neurol., 18, 483 



(1908). 

 Chapman. Brit. J. anim. Behav., 2, 146 



(1954). 

 Clark. J. exp. Zool., 51, 37 (1928). 

 Dolley. J. exp. Zool., 20, 357 (1916). 

 Dolley and Wierda. J. e.rp. Zool., 53, 129 



(1929). 

 Fraenkel. Z. vergl. Physiol., 6, 385 (1927). 



Biol. Rev., 6, 36 (1931). 

 Franz. Internat. Rev. Hydrobiol. {Biol. 



Suppl.), 3, 1 (1911). 

 Garrey. J. gen. Physiol., 1, 101 (1918). 

 Gotz. Z. vergl. Physiol., 23, 429 (1936). 

 Holmes. J. cojnp. Neurol., 15, 305 (1905). 



Kennedy. Proc. Zool. Soc. Lond., 109A, 



221 (1939). 

 Klein. Z. wiss. Zool, 145, 1 (1934). 

 Mast. J. anim. Behav., 2, 256 (1912). 

 J. exp. Zool., 38, 109 (1923). 

 Amer. J. Physiol., 68, 262 (1924). 

 Meyer. Z. wiss. Zool., 142, 254 (1932). 

 Minnich. J. exp. Zool., 29, 343 (1919). 

 Radl. Utitersuchungen iiber den Photo- 



tropismus der Tiere, Leipzig (1903). 

 Rao. J. exp. Biol., 24, 64 (1947). 

 Richard. C. R. Acad. Sci. (Paris), 226, 



356 (1948). 

 Santschi. Rev. suisse Zool., 19, 117 (1911). 

 Schulz. Z. vergl. Physiol., 14, 392 (1931). 

 Urban. Z. wiss Zool., 140, 299 (1932). 

 Wellington. Nature (Lond.), 172, 1177 



(1953). 

 Weyrauch. 



(1936). 



Zool. Am., 113, 115 (1936). 

 Wigglesworth. Parasitology, 33, 67 (1941). 

 Wolf. Z. vergl. Physiol., 3, 615 (1926) ; 



6, 221 (1927) ; 14, 746 (1931). 



Rev. Suisse Zool., 43, 455 



MENOTAXIS 



So far we have considered orientations either directly, or relatively 

 directly, towards or away from a source of light ; it is obviously of 

 greater biological importance if, in addition, an animal can travel at an 



1 P.adl (1903), Santschi (1911), Wolf (1927-31), Fraenkel (1927), Schulz (1931), 

 v. Buddi'nbrock and Schulz (1933), and others. 



2 ir./v-ma— Meyer (1932) ; Vanessa— Gotz (1936) ; Los ms— Weyrauch (1936) ; 

 Aedes — T, imedy (1939) ; Culex, Ano2}heles — Rao (1947) ; Pediculus — Wigglesworth 

 (1941). 



3 For iZa— Klein (1934). 



