4O LULU F. ALLABACH. 



Parker's experiments, I fed in one case six successive regions of 

 the disk, each till it had rejected food ; the next would then take 

 it as readily as at first. This refusal then cannot be due to a 

 general lack of hunger, and we must examine the other explana- 

 tions that have been given. 



2. "Judgment." If the animal comes to reject paper through 

 experience of the fact that the paper is not good for food, there 

 must be some way in which this experience is obtained. It 

 might be supposed that this comes through swallowing the food ; 

 being indigestible, its effect after swallowing might cause the 

 animal thereafter to reject it. This was tested by preventing the 

 swallowing of the paper. The animal was fed meat and paper 

 in alternation, as in Parker's experiments. But after the paper 

 had been carried to the mouth and was passing down in the 

 oesophagus, it was removed with a fine pair of tweezers. This is 

 easily done without disturbing the animal. Thus the bits of 

 paper never reach the digestive cavity. Yet the animal comes 

 to reject them as quickly as before. After a few alternations of 

 meat and paper, only the meat being completely swallowed, the 

 animal ceased to take the paper, while it still accepted the meat. 

 Hence the effect of the paper after it reaches the digestive cavity 

 is not the cause of its rejection. 



Furthermore, nothing like a contrast or comparison between 

 the meat and the filter paper is necessary in order to induce the 

 rejection of the paper. If successive pieces of paper were fed 

 alone to the anemones, they soon came to reject these as before. 

 In such cases it is noticeable that the animal takes a larger num- 

 ber of pieces of paper than when the paper is fed in alternation 

 with meat. The number of pieces required is about the same 

 as the number of pieces of meat and paper together that result in 

 rejection of the paper when the two are given in alternation. 

 This fact throws some light on the cause of the rejection, as we 

 shall see later. 



3. Repetition of Weak Stimuli, till Effect Fails. Is the loss 

 of the positive reaction to the paper due to the general fact that 

 weak stimuli, when repeated, gradually lose their effect ? This 

 was tested by excluding this factor from the experiments, in the 

 following way. A given specimen was first tested and found to 



