24 Trans. Acad, ^'c/. of St. Louis 



always niov(\s ])arallol to a wall and not at riglit anj^^les 

 to it. 



AVali-li tlu' behavior ol' tent caterpillars. They move 

 upward and outward, feeding when tliey lind the proper 

 materials. Later, satiated, they return to the tent. 

 "Negative ^cotropism when hungry, positive geotroi)ism 

 when satiated", some say. Or, take the recessional eater- 

 pillars. They move aloiiii: in a procession with the head 

 of one in contact with the larva Just in front of it. l^ead 

 them to the rim of a bucket and start the procession 

 around the rim. When the circuit has l)een completed, 

 knock aside the superHuous caterpillars and permit the 

 head of the leader to come in contact with the tij) of the 

 abdouuMi of file last meml>er of the ))rocessi(»ii. They 

 will contiiHK' to niai'<'li around llic rini iiour after hour.' 

 *' Positive thi^motropism", you say. Let us analyze the 

 behavior of such caterpillars. Arraii.ii:e a vertical maze 

 consisting of an uj)rii>:ht about one-inch in diameter to 

 which are attached a number of jointed arms. Let the 

 arms be so articulated that they can be bent in a variety 

 of ways. Such a maze contains no succulent buds nor 

 tender leaves for the larvae to nibble; hence there can 

 bo no reversal of tropism due to satiety. A cateri)illar, 

 when placed at the foot of such a maze will exjih)i'e it. It 

 may continue uj) to the center su])i)ort to. the toj) or it 

 may explore one or more of the arms. After a time it is 

 almost certain to descend the nuize to the .irrouud. This ■ 



behavior may be repeated seviM'al tinu's. Tlie ap])aratus m 



may i)e so manipulated that the caterpillar crosses tlie 

 light at several different ani^les, so that it moves toward 

 the wind, from the wind, and at ant;i(>s to it, and so that it 

 moves at times toward the earth an<l at otlier times awa.v 



'Fabrc, J. H.; Tlio Life of tin- Caterpillar, Translated l)y Alexander 

 Tcixcira de Mattos. Dodd, Mead & Co., lUKs i)}). 38-88. 



