OLFACTORY REACTIONS OF MARINE SNAILS 183 
TABLE 1 
Showing the distances in centimeters moved by mud snails and their arrivals up and 
down stream, when started midway between two lines 150 cm. apart 
in acurrent with and without food juices 
IN CURRENT WITHOUT FOOD JUICES IN CURRENT WITH FOOD JUICES 
ANIMAL | TRIAL Distances moved Arrivals Distances moved Arrivals 
NUMBER |NUMBER 
Up Down Up Down Up Down Up Down 
stream stream stream stream stream | stream | stream | stream 
1 75 0 + 80 5 + 
1 2 0 75 =F 75 0 + 
3 0 ao =e Wo 0 = 
4 0 75 “fF 81 6 + 
1 0 + 75 0 + 
fs 2 90 Bol) 2e 117] 42 | + 
z 3 120 45 AF 119 44 Le 
4 51 126 a 134 59 =F 
1 18 93 aF 75 0 + 
3 2 116 Al + 1173 37 — 
3 0 75 cs 63 | 138 ea 
4 of 82 + 173 98 + 
il 0 75 +f 61 136 a 
4 2 75 0 =F 4 79 
3 0 75 +. 80 5 Hie 
4 15 90 oe 10 85 
1 530 a = Tiana au 
: 2 632 | 0 -- 75 0 = 
3 87 12 a 75 0 J 
Ane 0; nce =: 75 O: | ee 
Mgal.:...) -770 1 toa lee 12 | 1636| 736 | 16 4 
1 Closed trial with snail resting at 53 em. line. 
? Closed trial with snail resting at 63 em. line after starting it once by touching 
it. 
Of the twenty preliminary trials in the current alone, there 
were eight in which the snails either arrived at the seventy-five 
centimeter line upstream, or showed a marked tendency to 
move against the current. The number of arrivals upstream 
was doubled, however, when the fish were placed near the head 
of the current. The five snails traveled 770 centimeters against 
