624. MR. W. H. HUDSON ON THE HABITS OF HERONS. [Nov. 16, 
condemned by the imperfections of their organs to a perpetual 
struglge with misery and want. 
Much as the different species vary in size, from the Ardea cocoi 
to the diminutive Variegated Heron of Azara (Ardetta involucris), 
no bigger than a Snipe, there is yet much sameness in their confor- 
mation, language, flight, nesting and other habits. They possess a 
snake-like head and neck, and a sharp taper beak, with which they 
transfix their prey as with a dart—also the serrate claw about 
which so much has been said, and which has been regarded as an 
instance of pure adaptation. A curious circumstance has come under 
my observation regarding Herons. Birds in poor condition are very 
much infested with vermin ; whether the vermin are the cause or effect 
of the poor condition, I do not know; but such is the fact. Nowin 
this region (the Argentine Republic) Herons are generally very poor, 
a good-conditioned bird being a very rare exception ; a majority of 
individuals are much emaciated and infested with intestinal worms ; 
yet I have never found a bird infested with lice, though the Heron 
would seem a fit subject for them, and in the course of my rambles [ 
have picked up many individuals apparently perishing from inanition. 
I do not wish to insinuate a belief that this immunity from vermin 
is due to the pectinated claw; for though the bird does scratch 
and clean itself with the claw, it could never rid the entire plumage 
from vermin by this organ, which is as ill adapted for such a purpose 
as for “giving a firmer hold on its slippery prey.” 
The Spoonbill has also the serration, and is, unlike the Heron, an 
active vigorous bird, and usually fat; yet it is much troubled with 
parasites, and I have found birds too weak to fly and literally 
swarming with them. 
I merely wish to call the attention of ornithologists to the fact that 
in the region where I have observed Herons, they are exempt in a 
remarkable degree from external parasites. 
Much has also been said about certain patches of dense, clammy, 
yellowish down under the loose plumage of Herons. These curious 
appendages may be just as useless to the bird as the tuft of hair on 
its bosom is to the Turkey-cock ; but there are more probabilities the 
other way, and it may yet be discovered that they are very neces- 
sary to its well-being. Perhaps these clammy feathers contain a 
secretion fatal to the vermin by which birds of sedentary habits are 
so much afflicted, and from which Herons appear so strangely free. 
They may even be the seat of that mysterious phosphorescent light 
which some one has affirmed emanates from the Heron’s bosom when 
it fishes in the dark, and which serves to attract the fish, or to render 
them visible to the bird. Naturalists have, I believe, dismissed the 
subject of this light as a mere fable without any foundation of fact ; 
but real facts regarding habits of animals have not unfrequently been 
so'treated. Mr. Bartlett’s interesting observations on the Flamingoes 
in the Society’s Gardens, show that the ancient story of the Pelican 
feeding its young on its own blood is perhaps only a slightly embel- 
lished account of a common habit of the bird. The story of the 
scorpion “girt by fire” turning its weapon upon itself, may also be 
