Adjustment of the Gray Snapper to its Food. 305 



smooth, jelly-like masses without tentacles or other projections, and on one 

 h-urface of each the epithelium with its nettle-cells remained intact. These 

 pieces were stained blue and thrown to the Laboratory colony of gray 

 snappers alternately with blue atherinas, in the manner shown in table 14 

 at the left. 



After 3 normal atherinas, 7 blue atherinas and 7 cassiopea pieces were 

 thus thrown at noon. The atherinas were all taken at once ; 4 of the cas- 

 siopea pieces were taken but rejected, while 3 remained untaken. These 3 

 sank among the snappers and remained on the bottom. At i'' 30" p. m. 

 8 more blue cassiopea pieces were thrown, alternately with blue atherinas 

 and following 3 normal atherinas. The atherinas were again all taken, 

 while 7 of the 8 cassiopea pieces were refused and i was taken and then 

 rejected. On the following day (July 16) at 11 a. m. blue cassiopea and 

 blue atherinas were again offered, 8 of each, and with the result that but i 

 cassiopea piece was taken and this was afterward rejected (table 14, at 

 right). At times the snappers showed no reaction toward a cassiopea piece. 

 At other times they swam slowly toward the piece as though to take it, but 

 stopped when within a varying distance, never less than 6 or 8 inches, and 

 then turned away. Usually the movement toward the piece was but 2 or 3 

 mches; often there was no forward movement. The atherinas, on the other 

 hand, were seized with a rush and unerringly at the first rush. The attempt 

 was repeated forty-five minutes later (at 11'' 45'" a. m.), but with this dif- 

 ference : that after 4 blue atherinas and 4 blue cassiopea pieces had been 

 thrown, the remaining 4 of each thrown were red (table 14, right, below). 

 Both blue and red atherinas were at once taken, but all the cassiopea pieces 

 were refused. Although none of the cassiopea pieces were taken the snap- 

 pers rushed at the first piece thrown and nearly seized it. They behaved in 

 the same way toward the second and third pieces, but with each succeeding 

 piece their interest lessened, until they paid little attention to the last two or 

 three. In this experiment the atherinas and cassiopea pieces were handled 

 and thrown by dift'erent individuals so that there was no transfer of the odor 

 or taste of one to the other. 



During the 3 days this colony, consisting at this time of about 100 snap- 

 pers, actually swallowed 2 pieces of cassiopea and 2 of cassiopea combined 

 with atherina, while they took into the mouth and rejected 6 other cassiopea 

 pieces. In addition to this they examined, without touching, many of the 

 other pieces of cassiopea. As the result of this brief experience the last 13 

 cassiopea pieces remained untaken, while the percentage taken and rejected 

 declined from 57 at the beginning through 12.5 to 6.25, as shown in table 14. 

 The colony thus adjusted itself with great rapidity to a new possible-food 

 element, of unfamiliar color and form, but with the familiar unpalatable 

 <iualities of the medusa.' In doing this the individual snappers showed con- 



*That in this adjustment some of the snappers profited by the experience of 

 others is likely. We have here probably a form of imitation — a following instinct^ 

 but the data at hand do not warrant a critical discussion of the sul)ject. 



