PLATE 2 
EXPLANATION OF FIGURES 
7 Photograph of a normal ray (not the subject of an experiment), showing 
in side view, the attitude of repose which is normal in these animals. 
8 A photograph of the subject of experiment 31, showing a reaction affect- 
ing the tail only. *, indicates the region of the incision. 
9 A photograph of the subject of experiment 68, taken about two hours after 
the operation. (Cf. figure 13, a photograph of the same specimen taken half 
an hour earlier. ) 
10 A photograph of a normal ray (not the subject of an experiment), show- 
ing the natural position of the snout in the ray when at rest. 
11 A photograph, taken several hours after the operation, of the subject of 
experiment 30. This ray was one which, while it occasionally showed the typical 
reaction, rested for the most part in the attitude shown. 
12 A photograph, taken a quarter of an hour after the operation, of the sub- 
ject of experiment 70. The head is seen well raised but the tail appears unaf- 
fected. 
13 A photograph of the subject of experiment 68, taken an hour and a half 
after the operation. The tail is seen, somewhat indistinctly, well raised and 
turned to the left. 
14. A photograph of the subject of experiment 56, taken half an hour after 
the operation, showing an extreme reaction, the body being raised completely 
from the floor and supported only upon the lateral border of the pectoral fins. 
15 A photograph of a ray (XXXIII), not the subject of an experiment, but 
in the attitude which results from the breaking and retraction of Reissner’s 
fiber. This photograph was taken after the ray had been kept for four days 
under observation. 
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