40 FREDERICK S. BREED 



side with Morgan here and insist that the pecking reaction 

 improves in accuracy after birth. Whether, now, this is a case 

 of perfecting through habit, involves a still further problem, 

 that of the relation of habit to the instinct. One sometimes 

 speaks of the modifiability of an instinctive action like that 

 of pecking, but wherever this term has been employed in this 

 paper in connection with instinct no more has been implied than 

 the objective fact of improvement in accuracy, an increasingly 

 successful adjustment of parts in a more comprehensive func- 

 tion. The problem still remains, Is this development dependent 

 upon practice, or is it the natural functional correlate of struc- 

 tural maturation independent of practice ? Swallows are reported 

 to be able to fly without previous practice. If the pecking of 

 chicks could be successfully inhibited for a week's time without 

 doing violence to the normal physical condition of the animals, 

 would the accuracy of the reactions at the end of that time 

 average 36.67 on a scale of 50, the average for our lot of twenty- 

 one? There is evidence in support of the belief that such chicks 

 would very quickly be pecking with average efficiency, without 

 anything like the amount of practice chicks would have had 

 by this time when growing naturally. In other words, improve- 

 ment does not depend entirely upon practice. How much of 

 the improvement does depend upon practice? All of it, one is 

 led to believe from Morgan's pages. " Steadying of the inherited 

 organic apparatus " through preparatory efforts means improve- 

 ment through habit. Besides, overestimating, as he did, the 

 degree of perfection of the instinct at birth, he has left less 

 room for maturation and the effects of practice than there really 

 is. So far as the facts are concerned, the most one can say 

 is that the development of the pecking instinct proceeds some- 

 what without practice and is hastened by it. Maturation and 

 use run along in time together. No means has yet been devised 

 of measuring the amount either factor apart from the other 

 contributes to the development of the pecking reaction. 



The importance attached to individual acquisition as a factor 

 in development seems on the whole to become increasingly 

 restricted. The theory of the non-transmission of acquired 

 characters enormously narrows its scope in phylogenetic develop- 

 ment. Perhaps we shall discover its lesser importance in onto- 

 genetic development. The drinking reaction, for example, is 



