THE 



POPULAR SCIENCE 

 MONTHLY 



MAY, 1913 



A PROBLEM m EVOLUTION 



By Professor WILLIAM PATTEN 



DARTMOUTH COLLEGE 



I. The Scope of Morphology 



WHEN evolution became the accepted doctrine of the natural 

 sciences, it was incumbent on the zoologists to construct a 

 genealogy, or phylogeny, of the animal kingdom, one that would reveal 

 the great highways of evolution and disclose the historic sequence in 

 the rise of new kinds of animals, from the dawn of life to the present 

 time, from the protozoon to man. 



A complete genealogy of the animal kingdom, or even one as nearly 

 complete as the biologist may reasonably hope to produce, would be of 

 great value. It would represent the measure of our evidence that 

 animal evolution had taken place. It would constitute the framework 

 of the entire science of zoology, for at the root of every problem in 

 anatomy, embryology, physiology and paleontology is the question of 

 origin. It would be a moving historic picture of evolution, exhibiting 

 the successive stages of the process and the creative value of the accom- 

 panying conditions. 



The experimental methods of the laboratory and breeding-pen may 

 measure the pliability of life under the momentary stress of artificial 

 conditions, but only the phylogenetic history of large groups of animals, 

 extending over immeasurably long periods of time, under various 

 environments, can indicate the manner in which evolution actually did 

 take place; whether it was slow or rapid, uniformly progressive or 

 spasmodic, direct or tortuous; whether it drifted with the ebb and flow 

 of circumstance, or opportunely threaded its way through an unyield- 

 ing, but slowly changing, environment. And the manner in which 



VOL. LXXXII. — 29. 



