The Loss of the Eye-pigment in Gammarus cheureuxi. 
A Mendelian Study. 
By 
E. J. Allen, D.Sc., F.R.S., 
Director of the Plymouth Laboratory, 
AND 
E. W. Sexton, F.L.S. 
With Plates I to VII at the end. 
CONTENTS. 
PAGE 
Section I. ALprino ImMpERrect KyYE ‘ 7 ; 274 
Cross A. Albino Female AC x Red Male R.2. Plate I PRG) 
Cross B. Albino Female AC x Black Male K. A. 278 
Constitution of Blacks II, III, 1V and V 278 
Ei Reds IT, III, IV and V 284. 
35 F, Albinos 286 
Section IJ.’ ALL-wHiItE PERFECT EYE . : 
Cross C. Albino Female AB x White Male R.1. 
(0 4) 
J 
bob bh bo 
io.) 
~I 
Hypotheses I and II 88 
Constitution of Blacks VI, Cross C . 4 ; > 2 9ill 
Cross-matings is on es s - ; : P ; 4 - 18x08: 
Constitution of Reds _ ,, te ae : : : : ; : Od 
sp Albinos ,, 5 : : 5 ; : 3 ; 5 7 
Experiments with the Original Stock : ? ; d : : mood 
The Part-White Eye . é : : ‘ : : : : 5 a) 
Section II]. No-wuirr Hye. VII ; : : : ; : : gu BAD 
Section IV. CoLouruess Eyer : j : : ; : : : 5 Bail) 
Cross between Coloured No-white and Albino . 4 330 
Independent Origin of Coloured No-white and Albino No-white or Colourless 
eyes : : 5 . . . . : : : : . 336 
Constitution of the Colourless eye . 6 : ; : : ; . 338 
Section V. OneE-Stpep NO-wWHITES : 5 ; : : ; ‘ 5 BB!) 
SUMMARY ‘ 2 ‘ 3 F : : ; . : ‘ . eros. 
GENERAL CONSIDERATIONS : 5 : : 3 : ; : ; 5 > ats} 
EXPLANATION OF PLATES z ; ; L : eee oe : 2 pe a) 
In a paper by Sexton and Wing (Journ. M.B.A., Vol. XI, No. 1, 
pp. 18-50) a mutation occurring in the Amphipod Gammarus chevreuri 
Sexton, was described and figured (PI. I, Fig. 3) in which the usual black 
NEW SERIES.—VOL. XI. NO. 3. DECEMBER, 1917. ae 
