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SCIENCE 



[Vol. XVI. No. 408 



SCIENCE: 



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Vol. XVI. NEW YORK, November 38, 1890. 



No. 408. 



CONTENTS: 



Deaf, 



The lNTERSU||RlAaE OF 



AND THEIR EDUCATION 



E. M. Gallawdet 295 

 wobk at the new york state 

 aokicnltdbal experiment 



Station 299 



Notes and News 300 



Letters to the Editor. 

 Righthanded-ness and Effort 



J. Mark Baldwin 302 



Dull i 



Mount St. Elias. Wm. 

 Annular Phase of Venus 



Leivis R. Gibbes 303 

 A Problem in Physics 



H.A. Hazen 304 

 Children as Teachers 



E. A. KMcpatrick 305 

 Book-Reviews. 

 Civilization: An Historical Re- 

 view of its Elements 306 



AsiONG THE Poblishers 306 



LETTERS TO THE EDITOR. 



*** Correspondents are requested to he as brief as possible. Tlie writer's name 

 is in all cases required as proof of good faith. 



The editor willbe glad to publish any queries consonant with the character 

 of the journal. 



On request, twenty copies of the number containing his communication will 

 be furnished free to any correspondent. 



Right-handedness and Effort. 



Professor James replies in feienee for Nov. 14 to my letter in 

 the ^^sue of Oct. 31. taking exception to my interpretation of my 

 baby's use of her right band only for strong efforts. Without 

 summarizing the points at issue, I may indicate where it seems to 

 me his explanation lacks force. 



In the first place, I agree with him in all that he says about a 

 "natural prepotency in the (brain) paths to discharge into the 

 right arm." This is undoubtedly the explanation of right-hand- 

 edness, as my observations would indicate as far as they go. I 

 also agree with him in casting out the view that brings in con- 

 scious distinct memories and choices. They are a later develop- 

 ment. There is nothing in my letter to indicate such a view. On 

 the contrary, I accept the "semi-reflex" theory of the possibilitj 

 of the use of either hand. But quite apart from these facts of the 

 nervous basis, the question arises: What is the least difference in 

 consciousness required to explain the preferential use of the right 

 hand when effort is involved ? 



Now, Professor James kindly says that my observations " show 

 how strong stimuli may produce more definitely localized re ac- 

 tions than weaker ones. The baby grasped at bright colors with 

 the right hand almost exclusively." So far clear enough. But 

 whenever the same stimulus, say a piece of common newspaper, 

 was used in two experiments, at ten and at fourteen inches distance 

 respectively, the same "more definitely localized reaction" took 

 place in the second case ; but in this latter case the stimulus which 

 produced this "more definitely localized re-action" was fainter, be- 

 ing farther away, and the other conditions being the same in the 

 two experiments. The child always used the right hand for long 

 distances, even wlien the objective amount of stimulus remained 

 the same. The least inference, I think, is that the intensity of 

 tlie stimulus is not, at any rate, the exclusive cause of the more 

 definite re-action. Greater intensity might account for the use 

 of the right hand in some cases, but we certainly cannot hold at 

 the same time that lesser intensity accounts for it in others. 



The new element must represent the influence of former expe- 

 rience. I see no way to avoid this alternative. This is what I 

 meant by " memories," merely some kind of a conscious modifi- 

 cation which alters future re-actions. A purely physical modi- 

 fication would not sufRce, for it would have its fuU force also 

 in cases whioli involved no effort. Now, we may hold that 

 such " memories" are exclusively of afferent nerve processes, or 

 that they involve also a conscious modification due to efferent 

 nerve processes. If the former, we may attribute them to the 

 greater "promptitude, security, and ease" of rigbt-hand move- 

 ments, as Professor James suggests, or to former movements of 

 the eyes, involved in the visual estimation of distance (which I 

 am astonished he does not suggest) The first alternative, which 

 Professor James asks my ground for rejecting, is inadequate for the 

 following reasons. If such memories of afferent processes be of 

 movements with effort, they are already right-handed, and the 

 question is only thrown farther back; but, if they be of effortless 

 movements, then their motor influence would be perfectly in- 

 different, as I said in my former letter. My experiments show 

 this. If there had been differences in " promptitude," etc., the 

 child certainly would have shown preference tor the right hand 

 in effortless movements during the latter six months of the first 

 year. But, on the contrary, it was only when making violent 

 effort that there was any preference at all. Even after she 

 developed such preference in cases of effort, the use of her hands 

 when no effort was required continued to be quite indifferent. 

 Does not this indicate that the traces left by former afferent 

 processes of the same sense are not sufiScient? 



Moreover, in the absence of all feeling of the efferent current, 

 what could sensations of " promptitude," etc., be but the con- 

 sciousness of better adaptation and co-ordination of movements ? 

 But at this stage of life all the child's movements are so ataxic, 

 that there seems to be no practical difference between the two 

 hands in regard to the lack of the tactile delicacy in which path- 

 ological cases show motor ataxy to consist. 



If we seek for the needed " memory " among the sensations of 

 eye-movements in the case where the stimulus is weaker (more 

 distant), it is possible that we may find an afferent element which 

 brings up the intensity of the hand-memories to the necessary 

 pitch. 1 here may be a connection between the centres for feel- 

 ings of eye-movement and feelings of hand movement, so that 

 their united " dynamogenic " influence is the same as the high 

 intensity of the color stimulus. But, while freely admitting such 

 a possibility, it only pushes the question farther back again; for 

 how do we know that these eye- memories do not involve con- 

 sciousness of the efferent process which innervates the eye-centre? 

 And, besides this, there is another element in the hypothesis that 

 afferent elements from other senses may furnish the " kinaesthetic 

 co-efficient" for a given voluntary movement; namely, that such 

 activities of the other senses invoked took place along with move- 

 ments of the attention, which might, and probably do, contribute 

 an efferent element to consciousness. This possibility I have 

 never seen anywhere recognized. 



But in this case my experiments show conclusively that eye-move- 

 ment memories did not re-enforce the intensity of the arm-move- 

 ment memories; for, when the distance was more than fourteen 



