MAYER: DEVELOPMENT OF WING SCALES. 227 
of Noctuideo, Geometride, and Sphingide among moths, also consists 
of a derivative of uric acid, to which he gives the name “ lepidopteric " 
acid, and assigns the empirical formula C,,HjAzgNg0o. By prolonged 
boiling in HCl it is converted into uric acid, 
Urech ('91) demonstrated that in a large number of Lepidoptera the 
color of the urine that is voided upon emergence from the chrysalis 
is Similar to the principal color of the scales. 
Landois (64) many years ago made a careful study of the constitution 
of the blood of several species of beetles and butterflies. He found that 
when the blood is allowed to evaporate in the air crystals separate out. 
He also found that the blood consists chiefly of egg albumen, but that 
globulin, fibrin, and iron are also present. He called attention to the 
fact that the freshly drawn blood of the larvee of Lepidoptera is usually 
light in color, but that when it is allowed to dry in the air it generally 
becomes brownish or yellowish ; and further, that while the colors of the 
bloods are different for different species, it is very remarkable that 
the color which is assumed by the dried blood is apt to be similar to 
the ground color of the wings of the mature insect from which the blood 
is drawn. 
As before stated, I believe that the pigments of the scales are derived 
from the hemolymph or blood of the chrysalis, and my chief reason for 
believing this is that I can find no evidence that there is anything but 
hemolymph within the scales during the time when the pigment is 
formed. In considering the phenomena of pigmentation, therefore, it is 
important to know as much as possible about the physical and chemical 
properties of the hamolymph of the pupa. Accordingly, 1 have devoted 
some time to a study of the properties of the pupal hamolymph of the 
large Saturnideo, Samia cecropia, Callosamia promethea, and Philosamia 
cynthia, The hemolymph is under considerable pressure in the chrysalis, 
and when an incision is made near the shoulders of the wing cases it 
spurts out in large drops. I have made a chemical analysis of it, and find 
that its chief constituent is egg albumen, but that globulin and fibrin are 
also present. When the hemolymph is agitated with ether, the proteid 
substances are coagulated, and a clear amber-yellow solution is left. 
This amber-yellow solution may then be decanted off from the congealed 
proteids. When thus isolated the proteids are slightly yellowish, but 
they soon dry into a drab-colored mass, very much as the hemolymph 
itself does upon exposure to the air. Spectrum analysis shows that the 
clear amber-yellow solution owes its yellow color to xanthophyll. It 
will be remembered that Poulton (85) found that the green and yellow 
