44^ H. S. yennings. 



I. CHANGES IN BEHAVIOR DUE TO VARYING STATES OF 

 METABOLISM. 



Nagel ('92) and Parker ('96) have shown that the food reaction 

 of actinians toward weak stimuh becomes changed on repetition 

 of the stimulation. A Metridium or an Adamsia at first readily 

 takes filter paper soaked in dilute juice of crab meat. But after 

 this has been fed several times in alternation with pieces of meat, 

 the reaction to the filter paper becomes slower, and finally ceases, 

 while the meat is taken as readily as before. Torrey ('04) shows 

 that in Sagartia the state of hunger or satiety determines largely 

 the reaction to small solid bodies. A very hungry Sagartia 

 readily swallows inert bodies, such as filter paper and sand 

 grains, while a fairly well fed one rejects these, though it takes 

 meat. Has this effect of hunger and satiety any connection with 

 the changes observed by Nagel and Parker, or are these of a 

 different character.? What relation have they to the changes 

 due to experience in higher animals.? The whole problem of the 

 changes induced in behavior by changing metabolic states is one 

 of the greatest importance for an understanding of the adjust- 

 ment or regulation produced in behavior. I have attempted to 

 study this matter carefully in a number of sea anemones, and to 

 distinguish modifications due to this cause from those which 

 result from other factors. 



Stoichactis Helianthus. 



This large sea anemone has often a disk 10 to 15 cm. in diameter. 

 This is covered closely with short tentacles of uniform size, about 

 8 mm. in length.^ Stoichactis is voracious; it is usually when 

 captured ready to take large quantities of crushed crab appen- 

 dages. To three specimens I fed piece by piece nearly all of 

 three good sized ghost crabs (Ocypode). The food reaction 

 depends on contact with the meat itself — that is, on chemical 

 stimuli in combination with contact. Hard parts of the crab, 

 or other indifferent objects, are usually not taken, though in rare 

 cases even filter paper is swallowed. 



Food is taken in the following way: If a piece of crab's leg, 

 with some of the flesh exposed, is placed on the disk of a hungry 



'For photographs of the disk of Stoichactis, see Duerden, 1902, PI. I. 



