SCIENCE 
NEw SERIES 7 0 SINGLE CoPIEs, 15 CTs. 
VoL. XXXV. No. 897 FRIDAY, Marcu 8, 1912 ANNUAL SUBSCRIPTION, $5.00 
The Evolution of the Vertebrates 
and Their Kin 
By WILLIAM PATTEN, Ph.D. 
Professor of Zoology and Head of the Department of Biology in Dartmouth College, Hanover, N. H. 
EXTRACT FROM PREFACE 
It is not fifty years since the doctrine of evolution has been generally recog- 
nized, and during the latter half of that period surprisingly little persistent, or con- 
certed work has been done on the larger problems of phylogeny, and there is but 
little to justify the too common attitude that the possibilities of morphology are 
exhausted. Much disconnected fragmentary work has been done, but how little is 
known about the evolution of any one organ or system of organs; how very few 
animals, if indeed there are any, whose structure, development, and paleontological 
record are known with even approximate fullness or accuracy. What large class of 
animals is not separated from its next of kin by a gap too wide to be bridged by any 
known forms? Are these gaps due merely to a hiatus in the available records, or 
in our knowledge of them, or are they realities, representing periods of unusually 
rapid transformation due to sudden changes in the methods, or conditions of 
growth? If the gaps between the vertebrates and ostracoderms, and the ostraco- 
derms and arachnids appear to be wide ones, are they really any wider than those 
between the fishes and amphibia, the reptiles and mammals, or the cclenterates 
and arthopods ? ? Are not the evidences of genetic relationship of the same nature 
and value in one case as in the other? Is not the paleontological record more pre- 
cise and complete than we havesupposed? Will not embryology be less enigmatic 
under a new interpretation? If the arachnids are indeed the next of kin to the os- 
tracoderms, and through them to the vertebrates, is that after all so incredible? 
With this gigantic column in position, will not the remaining branches readily fall 
into their natural positions and the entire genealogical tree of the animal kingdom— 
take onthe convincing symmetry and coherency of reality, of a living, grow 
organism that contains the story of its own creation ? { = 
These are some of the problems bound up in the evolution of the vertebrates. 
Clearly it is not merely a question of constructing a convenient and more or lese 
satisfactory genealogy of the animal kingdom. The whole philosophy of creativs 
evolution is involved in the answer. 
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