82 THE PALEONTOLOGIC RECORD 



proper detail. Dr. Dall has already traced more or less completely the 

 genealogy of some of the species, and I have noticed certain series of 

 species the group of Corbula fossata, C. oniscus, C. wailesiana, etc., 

 being one of them deserving thorough study, but the paleontologic 

 work known to me has not as yet been done with the requisite detail to 

 form the basis of an opinion. The principal contribution to our gen- 

 eral knowledge of the evolution of organisms that paleontology can 

 make, however, is, I believe, in tracing out phylogenetic lines, and I 

 believe the discovery of the processes and causes of evolution must rest 

 with the experimental biologist. During the past few years very im- 

 portant experimental investigations have been made by several men, 

 and I venture to refer to their results, as I regard paleontology as only 

 an aspect of biology, and think the students in that field should utilize 

 the information gleaned in others. 



In the study of variation it has been shown that the selection of 

 fluctuating variations does not carry the species beyond a certain limit, 

 or the extent of the variation is limited, leading to the conclusion that 

 new species can not be produced by this method. I may here refer to 

 ecological surveys and the unreliability of conclusions reached by such 

 researches. Dr. Merriam several years ago presented a paper " Is Mu- 

 tation a Factor in the Evolution of the Higher Vertebrates ?" in which 

 he announced the conclusion that it was not. A critical examination of 

 Dr. Merriam's data showed he had not sufficient information on which 

 to base such a conclusion. His data possess value for the study of evo- 

 lution in that they indicate material that may be profitably investigated 

 by the experimental method. Attention should also be called to the 

 probable insufficiency of conclusions reached by studying material from 

 successive geologic horizons. For instance, suppose that two usually 

 distinct forms are connected by intermediates. There are no means of 

 ascertaining whether the intermediates represent transition stages be- 

 tween the two forms or are examples of blended hybridism. 



That new species may originate through saltation is rather definitely 

 proved ; but that it is the only process is not established. 



To consider the causes of the origin of new forms : That new forms 

 should originate from the old without the action of some new influence 

 seems to me impossible. The circle of possible combinations of already 

 existent characters could not be transcended, and there would result by 

 crossing only all the combinations possible within definite limits; this 

 would be especially obvious if the de Vries hypothesis of unit-characters 

 be true. Many experiments to determine the influence of various phys- 

 ical factors on individuals showed only somatic changes not of heritable 

 nature and the data accumulated seem definitely to prove that somatic 

 changes, or acquired characters induced through the soma, are not in- 

 herited. 



