120 Vniversltij of California Puhlications in Zoology. [^'ol. 4 



came to rest. Meanwhile, the other starfish, which had been for 

 a long- time in the jar, had seemingly become quite reconciled to 

 it ; it did not move about save when roused by special stimulation. 



The behavior described above is typical; I have observed it; 

 in many cases. It takes place in the same way whether the jar 

 to which the starfish is removed has fresh sea water running 

 through it or not. The varied changes in behavior are clearly 

 not due to corresponding changes in the external conditions. 

 They are of course determined in some way, as are the varied 

 activities of man and other organisms. Changes in the internal 

 condition of the organism set in operation changes in the ex- 

 ternal activity. 



It is clear then that the starfish does not always react in the 

 same way to the same external stimulus. It reacts, as does a 

 higher animal, not exclusively to one particular present agent, 

 but to the situation as a whole, including past external factors 

 as well as present ones. These past factors of course produce 

 their effect through the modifications they have induced within 

 the organism. 



The Righting Reaction. 



The foregoing pages have dealt with the behavior of the 

 starfish in regulating the income of material for carrying on its 

 life processes (food and oxygen), and in finding the proper en- 

 vironmental conditions, — avoiding those that are injurious and 

 seeking out those that are favorable. We now take up a matter 

 that is of equal importance with these, though serving to regu- 

 late the life processes in a somewhat more indirect way. The 

 starfish is so formed that its life activities can be well carried 

 on only when it is resting on its ventral surface. When turned 

 over, on its dorsal surface, locomotion is impossible, the finding 

 and capture of food must stop, the delicate gills are pressed 

 against the bottom, injuring them and impeding respiration, and 

 displacements of the internal organs must occur, that may be 

 harmful to their proper functioning. We find, as might be an- 

 ticipated, that there is a regulation of these bad effects by move- 

 ment ; the starfish turns itself again on its ventral surface. The 

 process of turning is known as the righting reaction. 



