108



Correspondence.



The best remedy is to soak the foot in warm water until quite clean and then

dip into a sulphate of zinc solution (5 gr. to an ounce of water), and this should

be done twice daily until the cure is complete.


I cannot say I have ever tried this remedy myself, but then I never had occa¬

sion to do so. It seems a lot of trouble to take over a bird of which I used to breed

dozens at one time, [but then even the commonest birds are difficult to get nowadays^


- A. G. Butler.


THE EVOLUTION OF FEATHER-PATTERNS.


Dear Dr. Renshaw,— Herewith I enclose article, and hope it will prove

satisfactory.


My idea is that originally a bird’s plumage was simply ornamented with

shaft-streaks more simple in pattern than in the Greenland lalcoiq, possibly, at

an earlier stage, even these did not exist.


That the development started froi a simple fusiform streak to the hastate

type i , then to the sagittate A , next to , this form which subsequently

gave rise to submarginal or marginal borders, the shaf ;treak sometimes persisting,

but frequently disappearing by absorption.


However, you will see what I say about en colour is growing in the


breast and throat feathers of the Grey Cardins s, tarts at the shaft,



and so daily extends until the buffish feathers have become entirely crimson (or

black). I watched similar growth of coiour in Pyromelana when assuming the

summer plumage (the greater part of the plumage is not moulted out in the spring,

whatever some excellent ornithologists may believe. In the first volume of the ‘ Emu,’

p. 71, E. M. Cornwall mentions the case of a Galah Cockatoo which injured its wings

when flapping, am<‘ the whole of one side of his plumage became darker and the pink

of the injured side became dark red.” He remarks : “The vane of a feather is usually

regarded as physiologically dead, but this occurrence, though an exceptional one,

seems to strengthen the argument of those who contend that it is possible for

colouring matter to pass from the basal gland throughout the whole structure.”

That this is so is evident in the case of Turacus, in which the scarlet colouring in

the wings is soluble in water, gets washed out in heavy r-ains, but is gradually

recovered when dry weather supervenes.


A very common type of pattern in birds is one in which the head, breast,

collar, rump, and sometimes vent are each sharply defined in colour: then you have

combinations of two or more of these characters, but the general design is far less

varied than is the case with lepidopterous insects; but of course the beauty of

many birds is much enhanced by secondary sexual characters.


These matters interest me far more than classification. I suppose the

interesting conversations which I used to have in my youthful days with Darwin,

Bates, Trimen, and others roused a spirit of questioning the cause of things in my

mind, and it still sticks to me even now at the age of 78. Will it continue to the

end if I attain to my father’s age, 97? Believe me,


The Lilies, 124, Beckenham Road, Yours very sincerely,


Beckenham, Kent; November 29th, 1917. A. G. Butler.


[Dr. Butler’s article which accompanied the letter is of great interest and

value, and we hope to publish it at an early date. — G. R.]



