THE METAMORPHOSIS OF FLIES. 603 
known circumstance to those persons who inhabit the country, 
however unenlightened ornithologists may be in the matter. It 
furnishes a case parallel with that related by Audubon, of the 
herring gull nesting in communities, in trees. 
I will conclude with an observation on the digestive arrange- 
ments of the sage cock—a bird which I have only lately seen 
alive. It has been repeatedly stated to feed exclusively upon 
sage leaves. All those I shot had the craw full of grasshoppers 
and other insects, and had nothing else in it. It has also been 
asserted that the bird has no gizzard; the gizzard is indeed quite 
thin, so as to appear merely a membranous bag, but for all I 
could see that the disposition of the muscles is the same as that 
obtaining in other gallinaceous birds. The case is simply a 
reduction of the amount of muscle, without any essential change 
in arrangement. At least this is the result of an off-hand dissec- 
tion, such as one would be likely to make in the field. The 
change is an evident adaptation to the soft and succulent or juicy 
nature of the bird’s food —buds, leaves and insects, instead of 
grain. There is another peculiarity of this bird, also dependent 
upon its food, and the nature.of the digestive process. When 
flushed it almost invariably acts in the way which has given the 
green heron (Ardea virescens) its inelegant popular appellation.— 
Milk River, at 49°, July 25, 1874. 
THE METAMORPHOSIS OF FLIES.* I. 
BY DR. AUGUST WEISSMAN. 
: Berore I pass to the general results of the foregoing observa- 
tions a short chronological exhibit of all the processes of develop- 
ment will be useful. 
In agreement with all the earlier observations on the embry- 
ology of other insects it is apparent that during the life of the 
larva, in its outer form as well as the internal organs, only the 
LO MN ; ’s famous work, “ The Development of Diptera,” was published 
long ago as 1864, yet we feel sure our readers will value the translation of a few of 
i viously been rendered into English. The 
chapter is entitled “ View of the Phenomena of Development.”—A. 8. P- 
