328 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
TABLES IV AND V. 
Time of exposure varied. Distance constant at 150 cm. Evaluations made 
with reference — 
Table IV — to a single standard condition of medium migration,— 
Table V — to three graded migrations exhibited by animal 22. 
IV. V. 
Color. Red. BY. Red. YG. BY. 
Dist 
rags 150 50 | 150 150 50 | 150 | 150 
ee 20. Odea seo weo || 20: | 30 | 45.) bal ieae 
| 
Animal BP ah 
39. 9 5 3 
SONS 21) 27h ACS Aoi 2092. [26 18 2.5 
400 1 IN) sah 08 3521.3 15°) 48 1 |2.5| 399 2.5 oye 
A eS SRN Se S.BON 2 -| 2.5.) ave ei 
Amer tet S| ee A 12. | 0.5.) 1 |) 2.54 3.5. eee 
460 ie) | Be 315) Bio) 3, || 0.5|2 | -2.5 2. bale 
Ao Nes sie) 4 935 || 1 (| 2.2'| 2S 8 8 Se 
Ae | ah Bre 5) 3 |! 0:3 | 2/5 '| 3.35 a Reta 
pore || HORI 3 3 |) 25 oe 2.5 
aio: |) BC O05 | 83 3 eh) Sees 3 
Total {13.0 |23.0 |36.0 [30.0 |30.0 || 9.3 |19.4 [26.2 [21.0 |13.2 |23.2 
Average | 1.4 | 2.5 | 3.6 | 4.3 | 3 1 | 2.15) 2.9 | 3.59) 2 2a 
A computation from the average evaluations for R at 30 minutes and 45 
minutes and with reference to that of BV at 5 minutes yields by interpolation: 
From Table IV, BV at 5 minutes = R at 36.8 minutes 
a “© V, BV at 5 minutes = R at 39.0 minutes 
Av. = 37.9 minutes 
or BV = 7.6 R in terms of time of exposure required. 
In Tables IV and V are given also a few evaluations for exposures 
to red at 50 cm. for five minutes. When the average of these is 
compared with the average of the exposures at 150 cm. for forty-five 
