Correspondence. 153


Personally speaking, I do not believe (my opinion being based on the

microscopic examination of scores of feathers from different birds) that,

when once the pulp has wholly disappeared from the base of the calamis of

any feather, it ever again breaks through the dried septa or 'caps,' and

infuses new life or colour into the interior of the rhachis or barbs. Never-

theless in my work I have tried to approach the subject in an impartial

way, ready at an}' time to be convinced by the evidence of my senses.

The high standing of the ornithologists defending each side of the question,

left no other satisfactory way.


But I am thoroughly convinced that no good can come of reiterated

assertions, which in the present state of our knowledge can lead only to

useless and endless altercations.


What is needed in each case, is a continuous series of observations

made on the living bird in the hand, correlated with accurate microscopic

work. Attacked in this manner, the problem becomes a simple one, and no

ornithologist who has access to a Zoological Garden or a private aviary

need depend upon other than his own observations.


Mr. Bonhote acknowledges the spring moult of Larus, so that needs

no further discussion. The only point now at issue (I am confining my

remarks to this certain specific case!) is concerning any change in the

appearance of the old winter feathers, before they are replaced by the new

ones.


Now before Mr. Bonhote has any right to claim actual color change

in these feathers, he must demonstrate two things : first, that there is

actually a renewal of growth, — a re-opening of vital communication with

the cells of stratum Malpighii (as we are dealing with a pigment not a

structural color) ; and second, that the white tips of the winter feathers

receive a new supply of pigment from the rhachis and do not merely

become worn away and disappear, leaving exposed the dark proximal

portion of each feather.


In the collection of the New York Zoological Park we have two healthy

specimens of Larus ridibundus, brought last year from Europe, and I shall

at once begin to watch their spring changes, as the date of this letter

(Jan. 20th) is well ahead of the time which Mr. Bonhote sets ("February

and March "). My mode of procedure will be as follows and I trust that

Mr. Bonhote will perceive in it more of a desire for the truth and less of

"bluster" than he seemed to discern in my article under discussion.


To prove the first proposition, one has simply to pull out and at once

examine with the microscope a few of the winter feathers during the "ten

days or fortnight " when the " whole change " is taking place. Even a tyro

with the microscope can section the calamus or rhachis, and by an

examination of the very base, can tell whether there is any change going

on within the shaft.


In regard to the white tips,— if a number of feathers, say thirty or



