MAYER: COLOR AND COLOR-PATTERNS. 227 
pupa. The pupal blood of the Saturnidae is a proteid substance 
containing egg albumen, globulin, fibrin, xanthophyll, orthophos- 
phorie acid, iron, potassium, and sodium (p. 176). 
(4) In Callosamia promethea and Danais plexippus the pupal 
wings are at first perfectly transparent, then white, then impure 
yellow, excepting upon those portions which are destined to remain 
white in the mature wing. The mature colors then begin to appear 
near the central areas of the wings and between the nervures. Last 
of all, the nervures themselves become tinged with the mature 
colors. The central portions of the wings acquire their mature 
colors before the outer and costal edges, or the root of the wing 
adjacent to the body (p. 178, Plate 3). 
(5) The white stage in the development of color in the pupal 
wings represents the condition in which the scales are perfectly 
formed but lack the pigment which is destined to be introduced 
later (p. 178). (See, also, Mayer, ’96, p. 230.) 
(6) Dull ocher-yellows and drabs are, phylogenetically speaking, 
the oldest pigmental colors in the Lepidoptera. The more brilliant 
colors, such as bright yellows, reds, and pigmental greens, are 
derived by complex chemical processes and are, phylogenetically 
speaking, of recent appearance (p. 178). (See, also, Mayer, °96, p. 
232.) 
(7) While the number of species of Papilio in South America 
is 9 times as great as in North America, the number of colors which 
they display is only twice as great. Hence the greater number of 
colors displayed by the tropical forms may be due simply to the 
far greater number of the species, and not to any direct influence 
of the climate (p. 191). 
(8) The following laws control the color-patterns of butterflies 
and moths: (a) Any spot found upon the wing of a butterfly or 
moth tends to be bilaterally symmetrical, both as regards form and 
color; and the axis of symmetry is a line passing through the center 
of the interspace in which the spot is found, parallel to the longi- 
tudinal nervures (p. 183). (b) Spots tend to appear not in one 
interspace only, but in homologous places in a row of adjacent 
interspaces (p. 1883). (¢) Bands of color are often made by the 
fusion of a row of adjacent spots, and, conversely, chains of spots 
are often formed by the breaking up of bands (p. 183). (d) When 
in process of disappearance, bands of color usually shrink away at 
one end (p. 184). (e) The ends of a series of spots are more 
