136 K. S. LASHLEY AND JOHN B. WATSON 



Fourth week. Play rapidly changed from simple pushing and 

 grasping to the more complicated stalking and capturing of 

 objects in the cage. This was closely connected with his in- 

 creased interest in scraps cf solid food, as he first attempted 

 to eat at this time. The scratching reflex was perfected. The 

 very complex behavior of the adult appeared suddenly com- 

 plete. There is some evidence to show that he recognized food 

 by sight within a few days after he first tasted it. 



Fifth week. Apposition of the thumb and fingers was first 

 observed, muscular co-ordination spreading peripherally. Crude 

 experiments on his sensations of smell and taste indicated at 

 least a discrimination of stimuli as indifferent and unpleasant. 

 He attempted to draw the mother into his play. 



Sixth week. The adult expression of anger or impatience, 

 shaking his support violently, appeared suddenly. The thumb 

 was used much more in grasping. 



Seventh week. The first definite signs of interest in his own 

 body were observed. 



Eighth week. The use of the cheek pouches was acquired 

 during this week. 



Ninth week. Different vocal sounds w T ere first distinguished. 

 The method by which they were learned is not known, but from 

 their sudden appearance they seem to have been instinctive 

 rather than imitative. The first sexual activity was noted 

 during this week. 



By the ioth week the young monkey had become mature in 

 all but the sexual activities. He was lacking chiefly in muscular 

 control. 



Fifteenth week. From the ioth to the 15th week the progress 

 made was almost entirely motor. Play activities were still 

 very marked and unadaptive movements persisted. 



BEHAVIOR OF THE ADULTS 



The maternal instinct in these animals seems to be limited 

 to carrying and protecting the young one, permitting him to 

 nurse and keeping him clean of parasites. Within these limits 

 Dolly's care and' watchfulness are unceasing, but beyond them 

 she treats the baby much as she does the adults in the cage. 



