PHYSIOLOGY — PSYCHOLOGY. 381 



PHYSIOLOGY. 



Reichert, E. T., University of Pennsylvania, Philadelphia, Pennsylvania. 

 Continuation of study of differentiation and specificity of corresponding 

 vital substances. (For previous reports see Year Books Nos. 9-12.) 



During the past year further improvements have been made in the 

 methods of investigation. The work has been limited almost to the 

 study of the starches and certain other products of parent stock and 

 offspring, and the results have been qualitatively and quantitatively 

 entirely satisfactory. It is expected that this investigation will be 

 completed some time during the coming spring. 



PSYCHOLOGY. 



Watson, John B., Johns Hopkins University, Baltimore, Md. Research 



Associate of the Department of Marine Biology. (For previous reports 

 see Year Books Nos. 6, 9, 11, and 12.) 



During the summer of 1914 the experiments on the acquisition of 

 skill in archery, begun in Tortugas in 1913, were completed by Dr. K. 

 S. Lashley, of the Johns Hopkins University. An archery range 

 (40 yards) w^as constructed in the open. The specific object of the 

 experiment was to test the effect upon the acquisition of skill of different 

 amounts of daily practice. Twenty untrained subjects were divided 

 into three groups. One group shot 5 arrows with the English longbow 

 per day; another, 20 shots per day; and the third, 40 shots. 



The results of the experiments show quite conclusively that the group 

 shooting only 5 times per day improved in accuracy with less expendi- 

 ture of time in practice than was required by either of the other two 

 groups for the same amount of improvement. No appreciable dif- 

 ference appeared in result of practice distributed in 20 or 40 shots per 

 day. The relatively greater efficiency of short periods of practice 

 continuing for many days is in accordance with the results of the study 

 of animals and of speech habits in man, and indicates that in training 

 to muscular feats, both animals and man, the length of practice periods 

 required is usually too great for maximum efficiency. 



Professor Watson is continuing work on the homing pigeon along 

 two lines: First, the sensitivity of the pigeon to infra-luminous rays 

 is being tested by a method similar to that employed with the chick, 

 only in this case the method has been refined (see 1913 report of investi- 

 gations from the Marine Biological Laboratory) . In the second place, 

 the sensitivity of the homing pigeon to differences in (a) pressure, (6) 

 temperature, and (c) moisture of two air columns is being tested by a 

 physiological method. The pigeon is saddled comfortably in such a 

 way that respiration can be graphically recorded. Changes in the 

 rate, amplitude, and form of respiration are used as indicators of 

 sensitivity to the stimuli employed. In order to make the respiratory 

 curve stable, decerebrated pigeons will be used as controls. 



