September i, 192 i] 



NATURE 



25 



ire quite absent, in the dark. (Dr. Russ's words 

 ire : "I did four tests which seemed to give a posi- 

 ive effect.") 



3. That if a strong beam of Ught be allowed to 

 nil on the suspended system of the instruments 

 he gaze has no longer any effect. 



There are no grounds on which a definite con- 

 Jusion can be based, but I think the inference is 

 hat the effect is an optical one. 



Measurements should therefore be made to see 

 vhat electromagnetic rays are responsible for the 

 sfifects. (i) Are they stopped by a thick slab of 

 ead glass ? If they are, they are probably X-rays. 

 2) Are they stopped by sesculin or by )3 naphthol 

 lisulphonic acid? If they are, they are probably 

 iltra-violet rays. (3) Are they stopped by strong 

 methyl-violet? If so, visual rays may be re- 

 sponsible. {4) Are they stopped by a saturated 

 jolution of ferrous sulphate in water? If so, then 

 icy may be infra- red rays. 



In the next place tests should be applied to see 

 f the rays obey the ordinary laws of (a) reflection, 

 b) refraction, (c) polarisation, (d) inverse squares. 

 in fact, everything should be done to correlate 

 Dr. Russ's observations with known physical 

 aws, before metaphysical explanations are even 

 thought of. Since writing the above I have seen 



letter in the Lancet of August 6 in which Dr. 

 D. Suttie points out that another conclusion 

 Mm be drawn from Dr. Russ's experiments. For 



xample, in the experiment in which he found that 

 the side of the solenoid looked at rotated away 

 From him, what Dr. Russ was really doing was to 

 place the fixation point of his fovea co-ordinate 

 with the side looked at. But Dr. Suttie observes 



that all other parts of the solenoid would be 

 equally co-ordinate with some other part of the 

 retina, and that if all parts of the retina were 

 equally active there is no reason why any move- 

 ment should take place, since the forces on the 

 two sides would balance. Therefore he argues 

 that the effects obtained by Dr. Russ drive us to 

 the conclusion that the fovea is very^ superior to 

 the rest of the retina in the degree of its activity 

 [If it were very inferior, the same explanation 

 would equally hold good. — H. H.], and holds 

 further that the force ("if there be such") "is re- 

 fracted by the optical media of the eye in a manner 

 similar to light." 



Dr. Suttie then goes on to suggest that "the 

 deviation [refraction by optical media?] of the 

 force would supply a valuable clue as to its nature, 

 and that obvious controls would be to test persons 

 whose retinas are inactive through disease, or 

 who suffer from opacity of the eye media {e.g. 

 cataracts)." With these points of Dr. Suttie 's 

 letter I entirely concur. 



In his reply to Dr. Suttie's letter Dr. Russ 

 (Lancet, August 13) writes: "His [Dr. Suttie's] 

 reference to cataracts as controls is surely a feeble 

 suggestion." To me, at all events, it seems clear 

 that Dr. Russ has entirely missed the point of 

 Dr. Suttie's suggestion, viz. that tests on an eye 

 with a cataract would decide whether the effects 

 found by Dr. Russ are due to forces originating 

 from eye structures lying in front of or behind the 

 crystalline lens. Surely not a " feeble " suggestion 

 at all, but a very valuable one ! It seems to me 

 that it is not in regard to this suggestion alone 

 that Dr. Russ has misunderstood Dr. Suttie. 



Obituary. 



Prof. G. T. Ladd. 



been widely used in the universities of the United 

 States and of this country. 



So far back as 1887 Prof. Ladd published his 

 "Elements of Physiological Psychologv," which 

 was based, to a large extent, upon the second 

 edition of Wundt's "Grundzvige," but had 

 distinct merits of its own as an independent com- 

 pendium and discussion of the psychophysical 

 material then available. A revised edition ap- 

 peared in 191 1. . A more important and original 

 work of his is that which saw the light in 1894, 

 " Psychology, Descriptive and Explanatory " — 

 as was said of it at the time : " Literally a weighty 

 production, it turns the scale at three pounds 

 avoirdupois." 



Prof. James Ward's Encyclopaedia article had 

 appeared nine years before, yet Prof. Ladd's 

 volume, in certain respects, broke new ground, 

 to which, however, Prof. Ward's article had 

 obviously prepared the way. In particular, 

 the divisions of the book involved the complete 

 abandonment of the old and vicious doctrine of 

 ."faculties," and in it the conception was con- 

 sistently adopted that the formation and de- 

 velopment of a so-called faculty were themselves 



