THE COMPOUND EYE 176 



the retinular cells act as differentially orientated detectors ^ was based 

 on differences in the electrical response with variations of the direction 

 of polarization of the incident light. Such a suggestion, however, is 

 difficult to accept if it is agreed that the individual cells are not 

 furnished with corresponding axonal transmission ^ ; the theory could 

 not be made to adapt itself to the proven single impulse transmitted 

 from each entire ommatidium in the eye of Limulus (Waterman, 1950; 

 Waterman and Wiersma, 1954) ; moreover, such a change does not 

 seem to be invariable.^ It has also been suggested that the ultra- 

 structure of the rhabdome with its composite laminated and fenestrated 

 bodies, could provide a physical basis for this faculty (Fernandez- 

 Moran, 1956). An alternative hypothesis is that the responsible 

 structure is the corneal facet with its chitinous covering which is 

 birefringent, rather than any structure within the ommatidium 

 (Waterman, 1951 ; Berger and Segal, 1952). Wolsky (1929) and 

 Stockhammer (1956), however, were unable to detect any optical 

 mechanism which could act as an analyser in the entire dioptric 

 apparatus in the insects which they studied, and concluded that this 

 mechanism resided in the visual cells. It is obvious that further 

 research is required on this problem, and it may well be that more than 

 one mechanism is operative, differing in different species, or a mecha- 

 nism as yet unsuspected. 



Alverdes. fii'o?. Z6Z., 43, 577 (1924). Biitschli. Vorlesungeniiber vergl.Anatomie, 

 Ast. Zool. Jb., Abt. Anat., 41, 411 (1920). Berlin, 872 (1921). 



Autrum. Exjjerientia, 7, 271 (1949). Cajal and Sanchez. Trab. Lab. Invest. 

 Autrum and Gallwitz. Z. vergl. Physiol., biol. Univ. Madrid, 13, 1 (1915). 



33, 407 (1951). Rev. chil. Hist, nat., 25 (1921). 



Autrum and Stumpf. Z. Xafurjorsch., 5b, Chun. Bibl. Zool., 7, 193, 213 (1896). 



116 (1950). Claus. Manuale de Zool., Milano (1879). 



Baumgartner. Z. vergl. Physiol., 7, 56 Collins. J. ex;;. Zoo/., 69, 165 ( 1934). 



T, , ^ J" • rr r nr, ,,-,,n,,^ Comeli. Zool. Jb., Abt. Anat., 46, 573 

 Bedau. Z. wiss. Zool, 97, il~ (1911). (19->4) 



Bennitt. Physiol. Zool., 5, 49, 65 (1932). j^ ^-J ^^^^ gg^ 075 (1941). 



Berger and Courrier. C. B. Acad. Sci. t^ ,, pfif.aers irrh aes Physiol 12q 



(Pans), 234, 1208 (1952). 461 {\S) ^nyswi., i^y, 



Berger and Segal. C. R. Acad. Sci. „ , j, " !',. , , o-v c-i /ir^nr>\ 



(Pans), 234, 1308 (1952). ^"i./^y ^^p/"" " 3 ,^^^ //q^i^,^ = 



Bernhard. J. NeurophysioL, 5, 32 (1942). i^^'-^^f^J.^r ' ^°' ^ ^ ' 



Bernhards. Z. it'fss. Zoo/., 116, 649 (1916). ^'^■^' .'^^^ ^^"^^-'- , , , , ., 



Bott. Z. Morphol. Oekol. Tiere, 10, 207 ^^^ Sinnesorgane der Arthropoden ihr 



(1928). 



Bau und ihre Funktion, Braun- 



Brink. S. African J. Sci., 47, 162 (1951). schweig (1917). 



Brown. Quart. Rev. Biol., 19, 32 (1944). Dethier. J. cell. comp. Physiol., 19, 301 



von Buddenbrock. Grundriss der vergl. (1942) ; 22, 115 (1943). 



Physiol, Berlin (1937). Dietrich. Z. wiss. Zool, 92, 465 (1909). 



Bugnion and Popoff. Arch. Anat. micr., Doflein. Wiss. Ergebn. Dtsch. Tiefseeexp. 



16, 261 (1914). Valdivia, 6, 141 (1914). 



Burtt and Catton. J. Physiol, 125, 566 Edwards and Bouvier. Ann. Sci. Xat. 



(1954). (Zool), 13, 185 (1892). 



* Autruin and Stumpf (1950), Menzer and Stockhammer (1951) in the bee ; Stock- 

 hammer (1956) in Diptera and Hymenoptera. 

 2 p. 158. 

 ^ de Vries et al. (1953), in the blowfly, Calliphora. 



