570 PALEONTOLOGY 



tory of one of the great theories of the day. Many years ago, Waagen, 1 

 a German paleontologist, observed that the varieties or minor changes 

 in time (chronological varieties) differ from varieties in space (geo- 

 graphical varieties) ; that the latter have a variable value and are of 

 small systematic importance, while the former are very constant, and, 

 though seen only in minute features, may always be recognized again. 

 These varieties in time Waagen termed mutations. In 1891 Scott 2 un- 

 earthed this distinction of Waagen's and clearly defined it as the hered- 

 itary or phylogenetic change of animals in time. Previous to this, 

 Osborn, 3 without knowing of Waagen's statement, had discussed the 

 same facts of the birth of new characters, describing them as " definite 

 variations." Cope, it happens, did not follow this line of thought at 

 all; but many other paleontologists did, notably Hyatt, 4 whose pecu- 

 liar style and multiplicity of terms obscured his depth of thought and 

 extent of observation. Thus the term mutation acquired a definite 

 significance among paleontologists. 



It happened that De Vries, 5 the eminent Dutch botanist, reading 

 Scott's paper, mistakenly identified these new characters succeeding 

 each other in time with those which he was observing as occurring con- 

 temporaneously in plants, and he adopted Waagen's term for the 

 " mutation theory," which he has so brilliantly set forth, of the sud- 

 den production of new and stable varieties, from which nature pro- 

 ceeds to select those which are fit. 



If paleontologists are correct in their observation, mutations may 

 be figured graphically as an inclined plane, whereas De Vries's phe- 

 nomena in plants represent a series of steps more or less extensive. 

 Scott expressly excluded the element of discontinuity; and I believe 

 there is no ground whatever for the assertion that the phenomena first 

 named mutations by Waagen, and independently observed by many 

 paleontologists, are identical with the phenomena observed by De 

 Vries in plants. 



On the contrary, De Vries's facts accord with the favorite hypo- 

 thesis of Saint-Hilaire. They demonstrate the law of saltation. This is 

 the inevitable interpretation of the expositions of De Vries himself, of 



1 W. Waagen, Die Formenreihe des Ammonites subradiatus, Benecke's Pakont. 

 Beitrage, vol. n, 1869, pp. 179-257. 



2 W. B. Scott, On the Mode of Evolutionin the Mammalia, Journal of Morpho- 

 logy, vol. v, 1891, no. 3, p. 387; On Variations and Mutations, American Journal 

 of Science, vol. XLVIII, Nov. 1894, pp. 355-374. 



s H. F. Osborn, The Paleontological Evidence for the Transmission of Acquired 

 Characters ; American Naturalist, vol. xxm, 1889, p. 562. 



4 A. Hyatt, The Genesis of the Tertiary Species of Planorbis . . . Memoirs, 

 Boston Society of Natural History, 1883; The Genesis of the Arietidae, 1889; 

 Lost Characteristics, American Naturalist, vol. xxx, 1896, pp. 9-17. 



1 Hugo De Vries, Die Mutationstheorie, Bd. i, 1901, Bd. n, 1903; Species and 

 Varieties, Their Origin by Mutation, ed. by D. T. MacDougal, 8vo, Chicago and 

 London, 1905. Since this address was given, De Vries points out that the ootan- 

 ists have a prior claim, since Godron used this term before Waagen. 



