DAY: PIGMENT-MIGRATION IN EYE OF CRAYFISH. o20 
TABLE II. 
Intensity (i. e. distance) varied. 
Time of exposure constant (10 minutes). Evaluations were made with 
reference to a single arbitrary standard of medium migration. Last two 
columns give distances corresponding to equivalent migrations for red and 
blue-violet as deduced from the assigned evaluations. (Evaluations in paren- 
theses were ignored in making the deductions, because they represented 
migrations after the eyes had deteriorated in value.) From averages of these 
distances was computed the relative intensity of BV in terms of R, given in 
Equation I. Equation II was obtained after rejecting dubious cases. 
mee Blue-Violet ae tere riled 
ode ho Ai 50 | 100 | 150} 200 | 150 | 200 | 250 | 300| 400 || R. BV. 
Animal cm. cm. 
O. 2 Bele: Be ee 3 fly 0 150 250 
50 200 
Gi? 2 2 0 100 200 
my? C1) HO BOY 2 ea aa 150 200 
L 9 (apr) Mt 3 | 4 Fa 100 200 
150 300 
19 9 4 | 4 100 200 
20 9 Die) 90 Ac hs3 150 300 
229 | 4/3 | 2 5 | 4 150 | 250 
24 9 2 | 2 4 4 100 | 300 
20 9 2 0 1 4 f 50 250 
100 200 
28 9 eo LY 5 ra ae P50 200 
100 300 
150 400 
35 8. ui 0 1 en \G 150 300 
100 150 
36 4'gs 1 1 150 400 
38 9 4(3) | 2 1 3 i 0 50 150 
150 200 
- mx) vee mere 
Av.|| 107.5 | 247 
BV | 247 
R = 107.5 72-29 in terms of distance. 
BV = (2.29)? R in terms of intensity, or 
Equation I: BV=52R 
Equation II: BV = 5.6 R after eliminating G, K, 24, 25, 35 and 36, whose 
records were less easily compared. 
