56 



THE EYE IN EVOLUTION 



This type of response is characteristic of a large number of 

 Arthropods, particularly Insects, in laboratory conditions; most of 

 them react in a similar manner.^ Whether flying or walking deprived 

 of their wings, they proceed directly towards a light ; if two lights are 



Figs. 28-29. — Telotaxis in the Bee. 



Fig. 28. 



Fig. 29. 



Fio. 28. — The tracks of two bees in a relatively straight line towards a light 



(indicated by the circle). 

 Fig. 29. — The path taken by a bee in a directive light (indicated by the arrow), 



when the left eye is blackened. There are some circus movements to the 



right initially, whereafter the insect eventually walks directly towards the 



light (Minnich, 1919). 



Figs. 30-31. — Telotaxis in a Two-light Experiment. 



Lz 



Fig. 31. 



Fig. 30. — The tracks of 5 hermit crabs in their taxes towards two lights, L^ and 

 Lz- Each part of the track is directed towards one light only. 1, 4 and 3 

 travel directly to L2. 2 does so mitially and after a short time directs 

 itself towards L^ but rapidly resumes the path straight to L2' 5, after 

 an initial start towards L2, travels straight towards L^ (after von Budden- 

 brock, 1922). 



Fig. 31. — The track of an isopod, Aega. For a time it follows a zigzag course 

 alternating between ij and L^ until it finally makes up its mind to travel 

 straight towards L^ (after Fraenkel, 1931). 



^ The blow-fly, CalUphora vomitoria — Radl (1903) ; the aquatic nepid, Ranatra 

 — Holmes (1905) ; the fruit-fly, Drosophila — Carpenter (1908) ; the butterfly, 

 Vanessa — Dollej- (1916) ; the robber-fly, Erax rufibarbis — Garrey (1918) ; the honey- 

 bee, Apis — Minnich (1919), Clark (1928), Urban (1932) ; the drone-fly, Eristalis—M&at 

 (1923), Dolley and Wierda (1929) ; the flesh-fly, Sarcophaga—W eWington (1953) ; the 

 locust, Locusta nngraforia, in the hopper stage — Chapman (1954) ; and others. 



V 



