June 17, 1898.] 



SCIENCE. 



833 



lectures on optics, as shorthand names for the 

 processes in question. Precisely the same terms 

 have recently been coined by Hering and Hess 

 (Untersuchungen an total Farbenblinden, Pfl. 

 Arch., LXXI., Heft 3 and 4 ; March 2.5, l898). 



2. I spoke of Koenig's ' shift of excitability. ' 

 Mrs. Ladd Franklin rejoins that Helmholtz 

 and Fick had a shift of excitability. Of course. 

 If I had not known this from Hermann's Hand- 

 buch and the Oplik, at least I should have known 

 it from Mrs. Ladd Franklin's paper in Mind 

 (N. S., n., p. 478 ; Oct., 1893), in which the 

 facts are fully set forth. I wrote of Koenig's 

 shift, and not Fick's, because it was Koenig's 

 work, and not Fick's, that I wished to call at- 

 tention to. I was referring to current theories, 

 and had in mind the elaborate paper by Koeuig 

 and Dieterici, Die Grundemfindungen in normalen 

 und anomalen Farbensystemen und Hire Intensi- 

 idtsvertheilung im Spektrum (published in com- 

 plete form in the Zeifschrift, IV., p. 241 ; 1893), 

 and the pages in the Optik that rest upon the 

 authors' experiments (2d ed., pp. 366 ff.). 



3. On this basis — on the basis of a sheer mis- 

 statement, and of misapprehension of a position 

 that should have been clear from the context — 

 Mrs. Ladd Franklin charges me with concealing 

 under an ex cathedra manner a ' rather unusual 

 degree of ignorance.' The dogmatic manner of 

 my previous letter I explained and apologized 

 for : Professor Stevens accepted the apology in 

 the spirit in which it was offered. As for the 

 ignorance, the facts are these : 



No professor of a total subject — physics or 

 physiology or psychology — can keep adequately 

 abreast of every line of work in his science in 

 any given year. One has to 'keep up,' in a 

 rough way, with most things, and to devote 

 oneself in successive years to the detailed study 

 of a succession of single things. This year has 

 happened to be my optics year. I spent the 

 summer vacation of 1897 and the spare time of 

 the academic year 1897-8 upon optics. When 

 Professor Stevens' letter appeared I felt that I 

 was, perhaps, at the moment, better qualified 

 than most of my colleagues to give him the 

 bird's-eye view he asked for ; it seemed to be a 

 matter, if not of scientific duty, at least of 

 scientific courtesy, to pen a brief statement in 

 reply. Mrs. Ladd Franklin's sarcastic remarks 



about ' renewing my study,' etc., would apply, 

 I take it, equally well — or badly — to every pro- 

 fessor of every science in the country. Yet 

 science manages to get on. 



4. My position with regard to new theories is 

 misrepresented by Mrs. Ladd Franklin. See 

 my first letter, p. 605. 



5. I said that Mrs. Ladd Franklin's theory 

 had had ' grave experimental objection urged 

 against it.' It was open to the author of the 

 theory to call for proof of this statement. She 

 has preferred to give it a flat denial. ' " There is 

 no experimental evidence against my theory " 

 (p. 775). Fortunately, the literature is still ex- 

 tant. 



6. Mrs. Ladd Franklin concludes with an 

 attack on the color theory of my Outline of Psy- 

 chology. I would point out, in the first place, 

 that my last chance for corrections was Feb- 

 ruary 9, 1897 (see Preface to third ed.), whereas 

 the last installment of Muller's paper is dated 

 May 8, 1897. Should the book ever come to a 

 fourth edition, Hering and Mitller will be in 

 it, unless the optical situation changes. Sec- 

 ondly, as regards the confusion of the theory, 

 I did my best with the materials existing : I 

 took Wundt's theory and, under the influence 

 of Hillebrand's well known paper (fje&er die 

 specifische Helligkeit der Farben : in the Sitzungs- 

 ber. d. k. Akad. d. Wiss. in Wien, Feb., 1889), 

 carried the brightness side of it to its logical 

 conclusion. My position may have been over- 

 cautious, over-sceptical ; but I was trying to 

 write a scientific book. I can see no ground 

 for the charge of confusion. 



I fear that the above remarks contribute 

 nothing at all, directly, to science. I feel, how- 

 ever, that they should in justice be made, since 

 Mrs. Ladd Franklin has been allowed to run 

 amok through my previous letter. Indirectly 

 they may be of service, if they show Mrs. Ladd 

 Franklin that it is necessary to read before you 

 criticise, and that there are amenities to be 

 observed even in scientific controversy.* 



E. B. TiTCHENEK. 



*A small point, but typical. In the first five lines 

 of p. 774 Mrs. Ladd Franklin manages to misquote 

 me and to misname Bering's work. The Zur Lehre 

 is a collection of six papers, and we have two spe- 

 cifically theoretical papers from the year 1874. 



