192 T. C. STEPHENS 



out in the laboratory be subject to verification? And is not the 

 knowledge derived in the field by the process of observation or 

 experimentation also open to verification? 



The successful pursuit of scientific knowledge depends upon 

 the investigator's ability to observe and interpret; which, in 

 turn, is largely a matter of training. Whether the observer 

 sees through the lens of a microscope, the field glass, or with 

 the naked eye, matters little. He is just as liable to err by 

 the one as by the other, unless he is trained to recognize the 

 avenues of error. Various technical equipment may be called 

 to the aid of the observer, but, fundamentally, credibility is 

 determined by the student's capability and honesty. 



A given method of study must be appropriately used, and 

 its limitations recognized. The microscope is to enlarge an 

 object which is too small for direct observation. The field 

 glass, in effect, is to bring the object closer. Both are for the 

 purpose of rendering vision more distinct. It seems, therefore, 

 that the field glass is as legitimate an instrument for research 

 as the microscope. Its usefulness, however, is in the field. 

 The extent to which it may be applied is a detail. In the 

 identification of birds its use may be legitimate when the species 

 possesses marks by which the identification may be thus deter- 

 mined. When specific differentiation is based upon minor 

 variations in dimensions, the field glass becomes inadequate, 

 and it must be so recognized. On the other hand, is there not 

 also a danger that the taxonomist may go too far with his 

 millimeter rule in the differentiation of species and subspecies? 



It may be admissible to again raise the question whether, 

 in the long run, science is advanced by the excessive multiplica- 

 tion of named forms which are based upon such minute structural 

 details that the methods at the disposal of the field student 

 become inadequate. 



The tendency toward species ' ' splitting ' ' under the technical 

 term of ' revision ' ' does not seem to be waning, and its bear- 

 ing upon the field zoologist is so pertinent that the mention 

 here may not be out of place. 



Those ornithologists who are interested in the subject from 

 the practical, or economic standpoint are concerned chiefly with 

 the various problems which grow out of the question of the food 

 of different species. Usually, the end in view, from this stand- 

 point, is to determine the relation of birds, and of any given 



