SPECULATIVE ZOOLOGY. 195 



or common origin. Nor is it an unfortunate circumstance that coal- 

 tar can not be used as a substitute for bitumen, since the former con- 

 tains many constituents that are more valuable for other purposes, 

 while Trinidad offers an inexhaustible supply of the latter. 







SPECULATIVE ZOOLOGY. 



By Professor W. K. BEOOKS, 



OF JOHNS HOPKINS UNIVERSITY. 



AT a time when most naturalists who venture at all beyond the facts 

 of life-science are busied with the attempt to trace the relation- 

 ship between the various groups of living things, and to express this 

 relationship in a tree-like system of classification, it is startling to hear 

 from one of the highest authorities on life-science the statement that 

 " the time for genealogical trees is past. ... It seems hardly cred- 

 ible that a school which boasts for its very creed a belief in nothing 

 which is not warranted by common sense should descend to such 

 trifling." * 



It is true that the context seems to show that the author does 

 not visit all attempts at phylogenetic classification with the sweep- 

 ing condemnation which the passage quoted seems to imply, yet the 

 fact that a high authority upon the subject has made such a statement 

 at all is a sufficient reason why those who believe that the status of 

 modern morphology is not without a basis of common sense should 

 carefully revise their grounds for this belief, in order to decide for 

 themselves how far, and in what shape, such speculations upon the 

 relationships of organisms are admissible, and favorable to the progress 

 of science. 



The belief that the present life of the globe is only a very small 

 part of its total fauna and flora is hardly more firmly fixed in the 

 minds of the present generation of naturalists than the belief that the 

 recent species are the modified descendants of those which are extinct; 

 and there are few who would not acknowledge that their conception 

 of the origin of life would be fairly illustrated by comparing the living 

 things of the past and present to a great, many -branched tree, buried 

 in the ground so that only a few scattered groups of twigs are exposed 

 to our direct observation, although these groups show by their ar- 

 rangement a vague and indefinite relation to the branches below the 

 ground. The twigs which are exposed are the living things which now 

 people the earth, and those twigs and branches and larger trunks which 



* " Embryology and Paleontology," by Alexander Agassiz. Address before the 

 American Association for the Advancement of Science. 



