276 J. F. SHEPARD AND F. S. BREED 



the method devised to test the effect of maturation apart from 

 practice. The feeding reaction in its first intent being a response 

 to an optical stimulus, it was thought feasible to prevent prac- 

 tice by keeping the animals in darkness prior to their first tests. 

 To protect the chicks from light from the first, the incubator 

 door was opaquely sealed before the date of hatching, and 

 when the hatch was considered finished the animals were re- 

 moved from the incubator to a dark-box during the night while 

 the single window in the incubator room was shaded as a further 

 precaution. The dark-box was lined with dull black cotton 

 cloth and covered with the same material. In this box the 

 chicks were transferred to a dark-room and kept therein, under 

 a dark-curtained indoor brooder which had been made ready 

 in advance. This brooder was heated by a system of galvanized 

 sheet iron pipes which led from an oil lamp outside the dark- 

 room to the brooder radiator and thence returned to the out- 

 side. No light from the heating apparatus was evident in the 

 dark-room. The room in which the chicks were thus kept was 

 entered through an adjoining dark-room so that light might 

 not be admitted with the going and coming of the experimen- 

 ters. The dark-room conditions having been satisfactorily ar- 

 ranged, a greater difficulty was confronted — that of artificially 

 feeding the animals during the period of dark-room confinement. 

 It was soon found futile and seemingly unnecessary to attempt 

 feeding during the first twenty -four hours of this period. The 

 chicks, as a rule, did not react positively to food on the first 

 day. On the second day of the period, however, they usually 

 began to take active part in the operation and made the attempt 

 at feeding a much more successful one. The food in this case 

 consisted of the regulation chick food, corn meal, and bread 

 crumbs, all slightly moist. The chicks were taken from the 

 dark-box one at a time, the body of an animal was clasped 

 over the back in the hand of the experimenter, the bill was 

 held open between the thumb and forefinger of this hand, and 

 the food inserted in the mouth by the hand that was free. The 

 chicks, when not taken too early, readily sw r allowed food thus 

 administered. The amount supplied was regulated by the felt 

 protrusion of the crops. Water was administered by a pipette 

 gently introduced into their mouths. In this manner the chicks 

 were fed and watered in the dark-room twice daily. The time 



