6o6 THE POPULAR SCIENCE MONTHLY. 



clay for their labors. Later, when the rains come, they serve as 

 drains to carry off the water which might threaten to invade the 

 dwelling. 



Comparative anatomy has long since removed the barriers, 

 once thought impassable, raised by human pride between man 

 and the other animals. Our bodies do not differ from theirs; 

 and, moreover, such glimpses as we are able to obtain allow us 

 to conclude that their psychic faculties are of the same nature 

 as our own. Man in his evolution introduces no new factor. 



The industries in which the talents of animals are exercised 

 demonstrate that, under the influence of the same environment, 

 animals have reacted in the same manner as man, and have 

 formed the same combinations to protect themselves from cold 

 or heat, to defend themselves against the attacks of enemies, 

 and to insure sufficient provision of food during those hard 

 seasons of the year when the earth does not yield in abundance. 



It must only be added, to avoid falling into exaggeration, that 

 man excels in all the arts, of which only scattered rudiments are 

 found among the other animals ; and we may safeguard our pride 

 by affirming that we need not fear comparison. If our intelli- 

 gence is not essentially different from that of animals, we have the 

 satisfaction of knowing that it is much superior to theirs. 



THE ORIGIN OF RIGHT-HANDEDNESS. 



BY J. MARK BALDWIN, 



PROFESSOR OF EXPERIMENTAL PSYCHOLOGY IN PRINCETON UNIVERSITY. 



question "Why are we right or left handed ?" has exer- 

 cised the speculative ingemiity of many men. It has come 

 to the front anew in recent years in view of the advances made in 

 the general physiology of the nervous system ; and certainly we 

 are now in a better position to set the problem intelligently and 

 to hope for its solution. Hitherto the actual conditions of the 

 rise of "dextrality" as the general fact of uneven-handedness 

 may be called in young children have not been closely ob- 

 served. It was to gain light, therefore, upon the facts themselves 

 that the experiments described in the following pages were car- 

 ried out. 



My child H was placed in a comfortable sitting posture, the 



arms left bare and free in their movement, and allowed to reach 

 for objects placed before her in positions exactly determined and 

 recorded by a simple arrangement of sliding rods. The experi- 

 ments took place at the same hour daily for a period extending 

 from her fourth to her tenth month. These experiments were 



