290 Papers from the Marine Biological Laboratory at Tortugas. 



much hesitation. They are treated Hke tentacled reds. Thev are followed 

 in turn by formalin normals and these are all taken at once precisely as at 

 the beginning of the series. 



In series II formalin normals offered at the beginning are all taken 

 at once. These are followed by formalin reds, a large number of which 

 are taken at once, more especially in the first half of the series. Nearly 

 all those taken with hesitation are in the second half of the series. Few 

 are taken with great hesitation, and none are refused. Formalin normals 

 offered at the end of the series are all taken at once. No tentacled fish were 

 offered in this series and it has little bearing on the general result. 



In series III formalin normals and formalin reds were both taken at 

 once at the beginning. These were followed by formalin tentacled reds, 

 only 8 of which were taken at once and these all in the first 15. Those 

 after the first 15 were taken with hesitation, which increased as the series 

 lengthened. All but 2 of the last 50 were either taken with great hesitation 

 or refused. The last 16 were refused. Formalin reds offered immediately 

 after the tentacled reds were all refused, while formalin normals following 

 these were all taken at once. The behavior of the snappers toward red and 

 white fish, which diff'er from each other only in color, is thus in striking 

 contrast at the beginning and at the end of series III. At the beginning 

 of the series the formalin reds are taken as readily as the formalin normals 

 (white), but at the end, after the snappers have had experience of ten- 

 tacled reds, formalin reds (untentacled) are refused, while formalin normals 

 (white) are still taken. The fact that formalin normals are taken at once 

 at the end of the series shows that any hesitation shown toward formalin 

 tentacled reds earlier in the series is not due to loss of appetite. The snap- 

 pers were hungry throughout each series. My notes record that formalin 

 normals were taken at the end of series I, "and with the greatest avidity." 



If either the first or third series could have been carried through on a 

 single snapper, then presumably all the tentacled red fish taken would have 

 fallen at the beginning of the series, the hesitation would then have graduallv 

 increased, and all the tentacled fish refused would have fallen at the end of 

 the series. In an experiment dealing with a large number of snappers ten- 

 tacled fish may be taken in any part of the series by snappers that have not 

 yet had experience of them. Nevertheless, as shown in table 11, tentacled 

 fish taken at once fall in the first part of each series. Thus in series I, all 

 but one of the tentacled atherinas recorded as " taken at once " are in the 

 first fourth of the tentacled part of the series. In series III. all the tentacled 

 fish recorded as " taken at once " fall in the first tenth of the tentacled fish. 

 On the other hand, tentacled fish " refused " fall chiefly near the end of each 

 series. Thus in series I eleven fifteenths of those refused fall in the second 

 half of the part of the series which they compose, \vhile in series III about 

 one-third of those refused fall at the end — a most significant fact. 



