542 THE POPULAR SCIENCE MONTHLY 



sented these considerations in a masterly manner. But there was no 

 time in the history of paleontology when they were not extremely obvi- 

 ous and familiar considerations. Chambers, in replying to his critics, 

 had fallen back upon the argument from the inconclusiveness of nega- 

 tive evidence. Even Hugh Miller, without greatly profiting by his own 

 precept, had pointed out " how unsafe it is for the geologist to base 

 positive conclusions on merely negative data." 32 And Spencer, in a 

 brilliant article written in 1858, 33 and published in the Universal 

 Review** in July, 1859, had urged that " along with continuity of life 

 on the earth's surface, there not only may be, but must be, great gaps 

 in the series of fossils;" and that "hence these gaps are no evidence 

 against the doctrine of evolution." He concluded : 



It must be admitted that the facts of Palaeontology can never suffice either 

 to prove or disprove the Development Hypothesis; but that the most they can 

 do is, to show whether the last few pages of the Earth's biologic history are or 

 are not in harmony with this hypothesis. 



In its later development, it is true, paleontology has been able to 

 produce some striking supplementary evidences of evolution. In a lim- 

 ited number of cases, approximately complete and closely graduated 

 series of forms of single orders or families can be exhibited in due 

 stratigraphic superposition. But all the elaborate and impressive 

 " form-series " have been worked out since 1859. Darwin himself made 

 no original discoveries in this field; and as late as the sixth edition of 

 the " Origin " the best evidence of the sort he presented from other 

 writers is, I believe, summed up in these two sentences : 



Several cases are on record of the same species presenting varieties in the 

 upper and lower parts of the same formation. Thus Trautschold gives a number 

 of instances with Ammonites, and Hilgendorf has described a most curious case 

 of ten graduated forms of Planortis multiformis in the successive beds of a 

 fresh-water formation in Switzerland. 



Of the two instances cited the first is vague — the great studies of 

 Waagen (1869) and of Neumayr (1871-5) in the Ammonites were still 

 to come; and the observations of Hilgendorf seem already, by the time 

 the sixth edition of the " Origin " was prepared for the press, to have 

 been shown to be erroneous. 35 The best known example, to English 

 readers, of a form-series is that of the Equidse. But Biitimeyer's 

 " Beitrage zur Kenntnis der fossilen Pferde " appeared only in 1863 ; 

 and Huxley's researches in this field, which were the consequence, not 

 the cause, of his acceptance of the theory of descent, were first pre- 

 sented to the public in his presidential address before the Geological 

 Society in 1870. 



6. The Argument from Persistent Types. — If good cases of gradu- 



82 "Footsteps of the Creator," p. 32. 



83 " Life and Letters of Herbert Spencer," II., 332. 



34 Reprinted in "Illustrations of Universal Progress," 1868, pp. 361, 376. 



35 Cf. O. Schmidt, " Descent and Darwinism," 1873, English tr., 1896, p. 96. 



