./ 11 tiniiiKj-Color Reaction E.vpcriincntally Established. 293 



contact with the tentacles. It was carried a little way, protruding from the 

 mouth, and then slowly swallowed. After approaching an atherina and 

 jerking back from it one or more times it often happened that a snapper 

 swam away. The atherina might then be approached by many snappers in 

 turn before being finally taken. The time taken by one or more snappers 

 in approaching an atherina and retreating from it is that which appears in 

 the record as " hesitation." 



Early in a series many snappers rushed toward each tentacled red as it 

 was thrown. Later in the series the number of snappers that responded bv 

 a rush grew progressively less, until toward the end of the scries no snap- 

 pers rushed forward when a tentacled red was thrown (evidence that the 

 splash of the falling atherina is not a sufficient stimulus to cause the rapid 

 approach of the snappers). The atherinas that were taken late in the red 

 series were taken by the few snappers that happened to be nearest the point 

 at which the fish struck the surface of the water. There was no general 

 rush toward that point. The nearest snappers approached slowly and be- 

 haved in the manner already described. In short, the extent to which the 

 individuals of the colony take part in the rush at any atherina appears to be 

 determined by the behavior of those snappers that happen to be nearest the 

 atherina when it strikes the water. If these nearest snappers rush vigor- 

 ously there is general participation by the other individuals of the colony. 

 If the nearest individuals approach more slowly, no such general participa- 

 tion takes place. A localized stimulus applied to one of the higher animals 

 may, if weak, produce only localized response, but may, if strong, throw 

 the entire organism into vigorous response. Similarly the vigor with which 

 a colony of snappers responds to an atherina appears to depend on the 

 extent to which the atherina serves as a stinuilus to the individuals nearest 

 to it. 



(c) Formalin reds folloiving formalin tentacled reds. — These were 

 treated precisely like tentacled reds. Probably the snappers would have 

 behaved no differently had all the reds been tentacled. 



{d) Formalin normals foUozving formalin reds (tentacled or unten- 

 tacled). — The behavior of the snappers is best shown by an extract from my 

 notes on scries I. " The change in the behavior of the snappers was most 

 marked. All of them rushed at once at each fish, so that the water fairly 

 boiled. A moment earlier very few snappers had paid any attention to the 

 reds and those that were taken were taken usually by the snapper that hap- 

 pened to be near." Sometimes when a change is made from reds to formalin 

 normals the first few of these are taken by the nearest snappers and with 

 slight hesitation. This hesitation rapidly disappears as more normals are 

 thrown, and the rushes quickly become as vigorous as possible and are 

 Iiarticipated in by the whole colony. The increasing vigor with which 

 the nearest snappers respond to successive atherinas makes itself rapidly 

 felt in the rest of the colony. 



Experiment _?J. — .As a control on experiment 32. in which the laboratory 

 colony was used, the following experiment was tried on July 19, 1907, at 

 jh .^gm p j^ ^ Q^ ^j.,g ^^,p5t lighthouse colony, which was without experience 

 of tentacled fi.sh. Atherinas were offered as follows: (i) 12 formalin nor- 

 mals; (2) 44 formalin reds; (3) 30 formalin tentacled reds; (4) 30 forma- 

 lin normals. All were taken at once without hesitation. No difference 



