86



Correspondence



(1) The crossing of different species may serve a definite purpose in

proving the relationship of certain birds to one another or the origin

of certain forms. For instance the breeding of Pheasants in captivity

has shown that the crossing of any two forms of the genus Phasianus

produces fertile offspring, whereas Phasianus mated to any other

genus of Pheasant results in sterile hybirds. The crossing of various

species of Agapornis also produces interesting results. But at the

same time it is to be feared that many take up hybrid breeding with no

other object than to produce curiosities.


(2) We understand that the Silver Pheasant ( Gennceus nycthemerus),

a common aviary bird, is nearly extinct in the wild state, and the wild

Golden Pheasant ( Chrysolophus pictus) is said to be very rare, while,

to turn to Mammals, the American Bison, Mountain Zebra, Blesbok,

and Bontebok have been saved from extinction by a life in semi-

captivity.


(3) Certainly no species of birds have been rendered extinct owing

to the desires of avieulturists to secure specimens.


(4) We know of no such list. Ed.]



EYE DISEASES


In reply to Mr. Hastings’ letter with regard to the reference, in

my article on Blue-winged Grass Parrakeets, to the susceptibility of

the species to eye disease.


It is a complaint of which, I am thankful to say, I have had, so far,

no personal experience ; partly, perhaps, because none of the Grass

Parrakeets we possess here at the Keston Foreign Bird Farm have

ever arrived previously infected ; and partly because, as I stated in

my article, we give nearly all our Parrakeets a separate aviary to each

pair of birds, thus minimizing the risk of subsequent infection.


The study of the diagnosis, cure, and prevention of the varied,

and, as in the case of Septicsemia, mysterious maladies that afflict

Parrakeets in captivity, and to some extent, according to Dr. Hamilton,

in a wild state also, is, comparatively, in its infancy. I imagine, how¬

ever, that the Xerophthalmia, which, in Mr. Hastings’ letter, he

refers to as being so prevalent among soft-food eaters, is entirely



