50 



SCIENCE 



[N. S. Vol. XXVI. No. 654 



of the arthrodira, points out similarities in 

 dental plates, but these might ally them as 

 well to chimseroids as to dipnoi — in the shape 

 of the caudal fin and its supports, which are 

 scarcely more dipnoan than shark-like (pleura- 

 canth) or ganoidean — in persistent notochord, 

 which might be as well shark-like, dipnoan or 

 ehimseroid, — in piinctation of dental plates, 

 which is a character by no means exclusively 

 dipnoan. So that one may, I feel, hardly con- 

 clude with Eastman that the lung-fish (Neo- 

 ceratodus) recalls " in its entire organization, 

 save for the absence of dermal trunk-armor- 

 ing, the principal features of the arthrodires," 

 or that there are present between the modern 

 lung-fish and the ancient arthrodire, " such 

 intimate structural resemblances [that they] 

 can not be explained by parallelism but point 

 plainly to common descent." Eastman is will- 

 ing to admit, on the other hand, that the 

 evidence is questionable that arthrodires had 

 a vestige of ventral limbs, and that they are 

 unlike dipnoans in possessing a shoulder- and 

 ventral-armoring. But even if we can picture 

 such a paleozoic descendant of primitive lung- 

 fishes, can we still imagine one which lackcj 

 also pectoral limbs, and opercular bones, and 

 which possessed on the other hand shoulder 

 joints rendering possible a curious dorso- 

 ventral movement of the headf Certain it is 



^ Eastman can answer these objections only by 

 minimizing their value, as when he maintains that 

 the operculum is represented in the rudimentary 

 spine of Dhiichthys, and that the movable attach- 

 ment of the rib to the cranium in Neoceratodus 

 is comparable to the intermovement of head and 

 trunk in the arthrodira. In his comparison of 

 the gnathals of arthrodira with the splenial of 

 dipnoans, he calls attention to a fleck of cartilage 

 fossilised on the outer (ectal) face of a gnathal 

 of Dinomylostoma as evidence of its attachment 

 to a meekelian cartilage; but this evidence, even 

 if accepted, would be as readily ganoidean as 

 dipnoan. It may be remarked, however, that the 

 structure in question is too obscure to warrant a 

 definite judgment as to its nature, and the fact 

 that the ectal surface of such a plate is sometimes 

 known to bear tubercles quite like those of the 

 usual head plates does not make the assumption 

 probable that the gnathal plates were placed far 

 from the surface of the head. 



that the resurrected doctrine of the kinship of 

 arthrodira and lung-fishes finds little support 

 in the recent studies of Hussakof and others, 

 which have shown that the gap between the 

 arthrodira and the pterichthyids is by no 

 means as wide as we have hitherto taught. 



Bashfoed Dean 

 Columbia Univebsity 



EVOLUTION theories: static, determinant, 



KINETIC 



In Science for December 7, 1906, Dr. Ort- 

 mann presents another of his series of reports 

 upon the kinetic conception of evolutionary 

 processes. It is very gratifying, of course, 

 that my suggestions are receiving so much 

 valuable time and attention, and the more to 

 be regretted that unfortunate methods of 

 study still interfere with the success of so 

 persistent an inquiry. 



Would it not be better, for example, to 

 simplify the issues by omitting the discussion 

 of the novelty or antiquity of the ideas, or 

 at least by postponing it until the ideas them- 

 selves have been clearly perceived? It will 

 then become evident to Dr. Ortmann that Dar- 

 win and many others have entertained kinetic 

 views of evolution, though not bringing them 

 to the point of definite formulation. 



In estimating the value of an interpretation 

 which differs from our own it is well to 

 suspend or lay aside temporarily the opinions 

 we have been entertaining, in order to see how 

 the alternative theory accommodates tlfe facts. 

 But instead of making a personal inspection 

 of the kinetic premises, Dr. Ortmann ties 

 himself fast by italics of certitude to his 

 static dogma: "If the environment remains 

 uniform, perfect uniformity of individuals 

 will result." This keeps him far outside of 

 the subject upon which he continues to inform 

 the readers of Science. 



Viewed at the long range imposed by this 

 fictitious barrier, many things look quite the 

 same which would be found very different on 

 closer inspection. Thus it appears to Dr. Ort- 

 mann that symbasis is the same as amphi- 

 mixis, whereas the two processes are on dis- 

 tinct lines and work in different directions. 



