Apkil 4, 1913] 



SCIENCE 



586 



indicating oscillatory movement is more re- 

 mote, and more easily detached from the sen- 

 sation. This detachment was diiEcult for W., 

 in the case of the tuning fork, because it was 

 for him principally an instrument for the in- 

 scribing of curves for time-measurement: the 

 sound of the fork signified its motion in space, 

 and the intensity signified the amplitude of 

 the sinusoidal line it could trace. This ob- 

 servation was made by W. and reported in 

 practically the words I have used. 



The results of observations made by several 

 other subjects give about the same threshold as 

 my own observations. One graduate student, J., 

 perceived no beats at c'-gS (56), obtaining per- 

 fect fusion at that point, although in audi- 

 tory experiments the fusion was not complete 

 until 64 was reached. This subject at no time 

 had tendency to confuse the sensation and the 

 motion. He is quite musical. 



Another graduate student, B., reported that 

 he was constantly troubled by the " visualiza- 

 tion " of the tuning-fork curve. He perceived 

 clearly the discreteness of the beats up to 

 e'-fS (78 -|-), but beyond that point was un- 

 able to decide whether the sensation was or 

 was not continuous. 



D., an undergraduate student with previous 

 training in palmesthetic work, and in dis- 

 crimination of rates and in certain other sorts 

 of psychological observation, obtained clear 

 fusion at c'-fS (78^) and undoubted discrete- 

 ness at c'-a (42§). Between these points, 

 there was doubt, and variation in his judg- 

 ments. 



It should be noted that the differential sensa- 

 tion (above about 80) is perceived as exactly 

 like that due to the addition of a third fork, 

 even by subjects who judge it to be a matter 

 of discrete phases. The problem is, therefore, 

 not to decide as to the character of the differ- 

 ential sensation merely, but concerns any 

 vibration of the same rate. 



The differential, when faint, may be made 

 perceptible in a way quite similar to that in 

 which the auditory differential is brought out, 

 namely, by stimulating with the lower of the 

 two forks alone for a moment, and then add- 

 ing the higher ; the resultant drop in the pitch 



of the clang is paralleled by the corresponding 

 change in the felt vibration. 



In the tests described herein, the forks were 

 not audible, they being weakly excited, and 

 used at a sufficient distance from the sub- 

 ject's head — at arm's length. In fact, they 

 were scarcely audible when brought up to half 

 the distance from the head. 



After making these observations, I am com- 

 pelled to view with suspicion the results of any 

 simple observations on the threshold of dis- 

 creteness and fusion in the palmesthetic or 

 haphic realms (and, indeed, in the auditory 

 realm also). I include my own observations 

 in this suspicion, along with others, for while 

 I may say that my observations have been very 

 careful, they can not do more than establish a 

 presumption. Mere observation (" introspec- 

 tion " in the sense of the word now happily 

 becoming obsolete) is productive of no certain 

 results; the measurements I have been de- 

 scribing are excellent vehicles for the demon- 

 stration of the fact, and I strongly recom- 

 mend them to any one who is inclined to rely 

 on the results of simple observation. These 

 observations are not experimental in the 

 proper sense of the word ; but fortunately it is 

 possible to apply experimental methods to the 

 problem upon which they bear. 



The palmesthetic difference sensation can 

 not be wholly without significance for the 

 theory of auditory perception. Although I 

 have a bias against the " telephone " theory, 

 I must admit that the perception of a differ- 

 ence in vibration rate by dermal or subdermal 

 nerves, and the detection of a differential rate 

 by these same nerves, seems to support 

 strongly the assumption that differences in 

 pitch of sound are not essentially connected 

 with differences in peripheral nervous ele- 

 ments, but that the same cochlear nerve termi- 

 nations may mediate different pitches, and the 

 same pitch be mediated by different termina- 



*'°^®- Knight Dunlap 



echinodehm hybridization 

 It is my purpose to call attention in this 

 note to certain facts, the consideration of 

 which may do something toward bringing 



