is impossible, therefore, to demonstrate trans-specific variation by any evidence that Palæontology can supply. The palæontologist (_pace_ Osborn) is utterly incompetent to pass judgment on the problem of interspecific relationship. As Bateson remarks: “In discussing the physiological problem of interspecific relationship evidence of a more stringent character is now required; and a naturalist acquainted with genetical discoveries would be as reluctant to draw conclusions as to the specific relationship of a series of fossils as a chemist would be to pronounce on the nature of a series of unknown compounds from an inspection of them in a row of bottles.” (_Science_, April 17, 1922, p. 373.) “When the modern student of variation and heredity,” says T. H. Morgan, “looks over the different ‘continuous’ series, from which certain ‘laws’ and ‘principles’ have been deduced, he is struck by two facts: that the gaps, in some cases, are enormous as compared with the single changes with which he is familiar, and (what is more important) that they involve numerous parts in many ways. The geneticist says to the palæontologist, since you do not know, and from the nature of your case can never know, whether your differences are due to one change or to a thousand, you cannot with certainty tell us anything about the hereditary units which have made the process of evolution possible.” (_Op. cit._, pp. 26, 27.) And without accurate knowledge on this subject, we may add, there is no possibility of demonstrating specific change or genetic relationship in the case of any given fossil.