H THE POPULAR SCIENCE MONTHLY. 



CLEWS IN NATURAL HISTORY. 



By Dr. ANDREW WILSON. 



IN the exercise of his scientific attainments, there is one aspect in 

 which the naturalist of to-day bears a certain likeness to the de- 

 tective officer. The latter is perpetually endeavoring to " strike the 

 trail " of the offender through his dexterity in the discovery of clews 

 to the movements of the pursued, and attains his end most surely and 

 speedily when the traces he has selected are of trustworthy kind. The 

 naturalist, on his part, has frequently to follow the history of an animal 

 or plant, or it may be that of a single organ or part in either, through 

 a literal maze of difficulties and possibilities. His search after the rela- 

 tionship of an animal may be fraught with as great difficulty as that 

 which attends the discovery of a " missing heir " or lost relative in 

 actual life ; and his success in his mission is found to depend, as does 

 that of the detective's work, simply on the excellence and trustworthi- 

 ness of the clews he possesses, and on the judicious use to which he 

 puts his " information received." It can not be denied, however, that 

 modern aspects of science and present-day tendencies in research have 

 largely increased the resemblance between the enforced duties of the 

 criminal investigator and the self-imposed task of the biologist. When, 

 formerly, the order of nature was regarded as being of unaltering kind 

 and of stable constitution, naturalists regarded animals and plants sim- 

 ply as they existed. There was of old no looking into the questions of 

 biology in the light of " what might have been," because the day was 

 not yet when change and evolution were regarded as representing the 

 true order of the world. When, however, the idea that the universe 

 both of living and non-living matter had an ordered past dawned upon 

 the minds of scientists, the necessity for tracing that past was forced 

 upon them as a bounden duty. With no written history to guide them, 

 the scientific searchers were forced to read the " sermons in stones " 

 which Nature had delivered ages ago. " Without clear and unmistaken 

 records to point the way, they had to seek for clews and traces to na- 

 ture's meaning in the structure and development of animals and plants; 

 and, as frequently happens in commonplace history, the earnest searcher 

 often found a helping hand where he least thought it might appear, and 

 frequently discovered an important clew in a circumstance or object of 

 the most unlikely kind. 



Readers whose tastes are not materially scientific have doubtless 

 heard much of " missing links " of nature, especially in connection with 

 the gaps which exist between the human territory and ape-land. Indeed, 

 the phrase has come to be understood as applying almost entirely and 

 specifically to the absence of connecting forms between man and the apes 

 forms for which, in one sense, no necessity exists, inasmuch as Mr. 



