Figure 66. — The snow trail as an example of the operation of point to point orientation to vertical objects such as tree trunks. 
Despite a 4'/2-inch snow, the rats duplicated the pattern of the trail (fig. 1 4) previously existing over the ground. The black 
squares in the background under the small pine frees are tags marking passages into the North Alley Burrow. The view 
is that of looking toward the North Alley Burrow from the direction of passage 3. Note how the snow trail passes just 
to left of the tree (No. 5 in fig. 65A) in the left foreground and just to the right of the two trees (Nos. 4 and 2 in fig. 
65 A) in the right background. The snow trail shown here was made on the night of December 24, 1948. However, 
its route is nearly identical with that of January 14, 1948, shown in figure 65C. See figure 67 for companion scene of 
another section of this snow trail. 
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