220 THE AMERICAN NATURALIST. | [Vor. XXXVI. 
vary from yellow to crimson. There is no blue rose, but a 
white variety of Rosa rugosa from Japan has a bluish tinge. 
Blue does not, indeed, occur in this family. While red is 
common, none of the Rosacez are adapted to Lepidoptera. 
The visitors are a miscellaneous company of flies, beetles, 
and Hymenoptera. 
This family exhibits a marked tendency in stem, leaf, bud, 
flower, and fruit to develop reddish coloration, — a tendency 
which is probably due to the chemical constitution of the sap. 
The smaller and less specialized Rosaceæ are yellow and white, 
and are visited by a variety of short-lipped insects. The increase 
of the white flowers in size and conspicuousness is usually 
attended by red coloration. Owing to the chemical constitution 
of the nutritive fluid, probably to its acidity (for when the petals 
of a rose are treated with ammonia they become blue), there has 
been no opportunity for the development of blue coloration by 
insects. With the enlargement of the perianth and the increased 
flow of sap, red tints have tended to appear by process of oxida- 
tion. The correlation of red coloring with an increased flow of 
the sap is well illustrated by the galls of the wild rose tree, 
which are often “as rosy as the rosiest apple." An abnormal 
flow of sap is caused to the part stung by the insect, and red 
coloration is due to the action of light, for it is of no service to 
the plant. Again, when the flowers of Crat@gus coccinea are 
stung by the gallfly the different organs all become red, and the 
change in coloring is accompanied by an increase in size. In 
some instances, according to Darwin, red colors indicate greater 
vigor on the part of the plant, and I have also observed that the 
dwarfing of red flowers under cultivation may cause them to 
revert to white. © 
There is nothing more beautiful in the vegetation of the tem- 
perate zone than an orchard laden with expanding blossoms. 
The great quantities of flowers form billowing banks of white- 
ness, tinged with rose and flecked with the vivid green of the 
unfolding leaf buds, from which exhales the well-known’ sweet 
fragrance of the: apple blossom. Of the Pomacez, or apple 
mol twenty-seven species. are white and five red or partially 
are reg and usually clustered. — 

