No. 423+] NORTHERN. POLYPETALOVS FLOWERS. 209 
as the pigments have been deposited .in the sepals, petals, or 
stamens: But while insects have been instrumental in develop- 
ing bright coloration, the particular colors of the different species 
have been very largely determined by other conditions. The 
yellow of Caltha palustris and Ranunculus has probably been 
preceded by no other color than. green. These flowers are 
visited by numerous flies, beetles, and the less specialized bees. 
Syrphida are abundant, a family of flies with many species, 
characterized by yellow markings, which would indicate that 
yellow was especially attractive to them. Müller states that he 
has seen Eristalis intricarius hover over the yellow flowers of 
Caltha, as the males hover over the females, then suddenly settle 
to suck honey or feed on the pollen. He also suggests that 
their love of yellow may have arisen from their visiting flowers 
of this color, and that sexual selection may have been guided by 
this taste. The white flowers of Batrachium have evidently 
passed through a yellow stage, but in other genera white or 
purple has been developed directly from the primitive green, as 
in Clematis. The blue flowers of Hepatica, Aquilegia, Delphi- 
nium, and Aconitum, which are very attractive to bees, appear 
to have passed through a yellow or white stage. The organs of 
the flowers of the Ranunculacez, according to Masters, more 
frequently revert to leaves than do those of any other family 
except the Rosacec. = . 
The Berberidaceze, Menispermaceze, Calycanthacez, and Lau- 
racez contain but few species. The "shrubs of Berberis, or 
barberry, have the wood as well as the calyx and corolla yellow. 
The flowers are attractive to bees and flies. The foliage in 
autumn is yellow‘and crimson. ` The three white-flowered species 
of the Berberidacez occur in woodlands and bloom in May. The 
Menispermaceze are woodland vines with small white flowers in 
panicles, or green in Calycocarpum, where the petals are wanting. 
The small flowers of the Lauracez are apetalous, but the calyx 
is yellow. The species are aromatic shrubs and trees. 
The original color of the Papaveracez, or poppy family, was 
probably yellow. The sap also of many genera is yellow or red. 
The beautiful flowers of Papaver are yellow or scarlet, with 
a darker center. If the flowers contained nectar, this central 
