i8g 3 . BIOLOGICAL THEORIES. 279 



by any evidence of any kind in support of it. In a healthy community 

 of students, such statements would do no harm, for only a morbidly- 

 credulous person unfit for scientific work would accept the state- 

 ment as true, on the authority of even the greatest anatomist living. 

 For an honest record of mere fact, we are often compelled to rely 

 upon the accounts given by others — we do not all have the opportunity 

 of dissecting Nautilus and other rare animals, and we none of us have 

 time to dissect one-hundredth part of the animals of which specimens 

 are easily obtainable. We are therefore compelled to rely upon each 

 other, and so glaring a falsification as that shown in the Steinmann- 

 Doderlein figure is, fortunately, not common. The discrepancy between 

 the description and the figure (in Zittel, for instance) would, moreover, 

 show any careful reader that either description or figure was false, if 

 not both. 



For facts, then, we must rely upon others, but must exercise 

 judgment in doing so. 



For opinions it is otherwise. To take another man's opinion 

 and accept it untested — as has been done in the case of the bird's 

 wing— is a sure way to something worse than mere error. Darwin 

 was one of the greatest men who have lived, and his opinion is worth 

 more than that of most other men. To accept even his opinion, 

 however, except after examination of the argument upon which it 

 rests, is evidence that the man so accepting it is unfit for scientific 

 work. He will probably gain applause from " a popular audience" 

 (just as a good encyclopaedia may gain approval), but if he holds 

 opinions otherwise than as the result of conviction he is only a walk- 

 ing encyclopaedia, and not nearly so good a one as the " Britannica." 

 So long as teachers continue to regard, as many do now regard, the 

 "passing" of their students as the object of their work or of their 

 students' work, so long will the "cramming" system continue to 

 convert men into walking encyclopaedias, stocked with second-hand 

 ideas, and incapable of either creating new ideas or of judging of the 

 value of the old ones. 



In a paper by Morse (7) the view that the bird's wing-digits are 

 II, III, and IV is put forward on the strength of the existence of a 

 supposed vestige of another digit on the radial side. Granting his 

 facts, such a vestige might be a vestige of a pre-pollex, so his 

 contention does not prove even that the usual view is erroneous, 

 though it lessens its apparent probability. It of course does not in 

 the least affect the view I have put forward, for he makes no attempt 

 to prove that the digits are II, III, and IV, but only that they are not 

 I, II, and III. The possibility of their being III, IV, and V 

 seems not to have occurred to him or to those who have adopted his 

 view. What W. K. Parker (8) regarded as a vestige of the digit 

 IV appears to me to be os pisiforme. 



Zittel (9) gives a figure described as " nach Owen." Owen's 

 figure shows four digits. Zittel has eliminated the innermost. It 



