THE MIGRATION OF INLAND BIRDS. 183 



refractive object. The reader will note that not only the details of 

 the markings are greatly changed, but the very outline of the figures. 



The fact that the most skillful microscopists of the age all differ upon 

 the true appearances of a common and not very minute object, and the 

 mici'oscope itself presenting to the vision the most opposite appear- 

 ances of one and the same object, should act as a caution to those who 

 accept too readily theories based upon microscopical research ; and 

 suggests that, in the cause of justice, when life is at stake, single- 

 handed evidence relating to the microscopical examination of ap- 

 parent blood-stains should be verified at least by a second person 

 before being accepted. 



Thus we see that the so-called revelations of the microscope are 

 but hieroglyphics, needing the interpretation of a mind of the highest 

 culture, and that while the microscope is a good servant it is a bad 

 master mighty in the hands of a Huxley, but as useless to a man 

 without the powers of discrimination as the chisel of Michael Angelo 

 would be in the hands of a Modoc. 







THE MIGRATION OF INLAND BIRDS. 



By CHAELES C. ABBOTT, M. D. 



AS understood by us, the migration of a bird is simply the deser- 

 tion of a given locality by that species for a certain, and always 

 the same, portion of each year. As an example, the common house- 

 wren {^Troglodytes cudon) is migratory, in that it remains in New Jer- 

 sey * only from late in April until late in September, having left its 

 Southern home for six months. 



Before endeavoring to determine the causes of this movement on 

 the part of some birds, we must first note the various features charac- 

 terizing the movement itself; for it may safely be asserted that no two 

 birds migrate alike, although the similarity is marked among the 

 various species of the same family. The most marked feature in 

 migration is the apparent uniformity in the time of its occurrence, 

 i. e., of the dates of the arrivals in spring, and of the departures in 

 autumn. Is this arrival in spring as regular as claimed by some, and 

 supposed by most people ? To the casual observer, and, indeed, to 

 many who have for years noted the first appearances of our various 

 birds, the ai-rival seems to be quite regular ; and, curiously enough, 

 we find many such observers insisting that, however late a bird may 

 be any one season, he is never earlier than a given date. Thus we 



* The observations upon which this essay is based were made by the author during 

 the past sixteen years, while residing at Trenton, New Jersey, and the dates of arrival 

 and departure of the various birds that we give refer solely to them, as seen in that 

 locality. 



