12 J. E. WODSEDALEK 



These results seem to indicate that the nymphs formed few, 

 if any, associations with pain resulting from a single daily dis- 

 turbance. For the specimens disturbed once in three days 

 there was even less evidence. Their behavior was almost iden- 

 tical with that of the undisturbed group, of which, during two 

 months, one manifested signs of fear only twice; another three 

 times; and four never stirred when I appeared or moved my 

 hand over the dish. In the forms disturbed several times each 

 day, however, even after making liberal allowance for acci- 

 dental movements, there remains abundant evidence that the 

 nymphs learned to associate my presence with discomfort. 



FORMATION OF ASSOCIATIONS IN FEEDING 



Training nymphs to come for food is a tedious task. This 

 is due to many reasons, the most obvious of which appear to 

 be: (i) The fact that in their natural environment they always 

 feed attached to the under side of stones with their dorsal side 

 downward; (2) they are moderate feeders and can go a long 

 time — as long as two months — without food; (3) they are strong 

 in their thigmotactic response, and great care must be exercised 

 in dealing with the specimens in order to avoid fear reactions. 



Six active specimens were selected and placed in separate 

 dishes without food, in a compartment of the room employed 

 in the experiments on fear. Daily observations were made as 

 regards the position of the nymphs, and considerable time was 

 spent each day in attempting to induce the different individuals 

 to follow food to the end of the dish nearest to me. 



At first a piece of alga w r as brought near the antennae of 

 the nymphs with a pair of forceps. Within a few days prac- 

 tically all of the individuals ate the offered particle. A number 

 of trials showed that only a small morsel of food was necessary 

 each day to insure the proper response the succeeding day. 

 As the nymphs would cling to the piece of alga with their fore 

 claws I would hold on to the food with the forceps and turn 

 the nymph so that it always faced me. This had to be done 

 with considerable care in order not to dislodge the insect or 

 interfere with its feeding. Then I would pull on the piece of 

 food, endeavoring to induce the nymphs to follow. At first 

 they would not move any great distance, but would plant them- 

 selves firmly and, if the pull was continued, the particle of 



