432 



LESLIE B. AllET 



rod-visual coll between the rod nucleus and the external reticular 

 layer was believed to cause these changes. Angelucci ('90) 

 made shnilar observations on the salamander, as did Garten 

 ('07) on Triton. 



Changes in the cylindrical outer member (figs. 1 and 2, prs.dst. 

 bac.rb.) have also been reported. Ewald und Kiihne ('78) first 

 observed a swelling of the outer member of the frog's rod as the 

 result of strong illumination. That Lederer ('08) obtained 



prs. dst. bac. vr 



prs. dst. con 



-prs. dst. bac. rb. 



mb. Iim. ex< 



Fig. 1 From a dark-adapted retina of tlie frog, Rana pipiens, showing the 

 positions assumed by the rods and cones. X 1130. ell. bac.rb., ellipsoid of red 

 rod; ell.bac.vr., ellipsoid of green rod; ell.con., cone ellipsoid; gtt.ol., oil globule; 

 mb.lim.ex., externa limiting membrane; my.bac.rb., myoid of red rod; my.bac.vr., 

 myoid of green rod; my.con., cone myoid; prs. dst. bac.rb., outer member of red 

 rod; prs.dst.bac.vr., outer member of green rod; prs.dst.con., outer member of 

 cone; ^t.nl.ex. external nuclear layer. 



results, the exact opposite of those reported by Ewald and 

 Kiihne, is assumed from the context of the previously cited 

 quotation (p. 431), and from his illustrations. 



Angelucci ('84) measured the length of the outer member of 

 the frog's rod and found it shortens in the hght; later ('90) he 

 confirmed this result by measurements of the large rods of the 



