1884. ] Botany. 823 
a little shower of pollen which is prevented from spreading by 
the fringe of hairs on the lower edge of the anther, and thus falls 
on to the head of the bee, at the very spot which a moment before 
had touched the stigma, and which will again touch that of the 
next flower she visits.” 
The “ path-finders” of the flowers of this genus have been de- 
scribed by Dr. Kerner in his interesting treatise on “ Flowers and 
their Unbidden Guests,” although he makes no mention of P. can- 
adensis, The inside of the lower part of the corolla is studded 
by numerous short, sharp bristles toward the mouth of the cor- 
olla. These form an effectual barrier against any insect passing 
its tongue to the nectar via the short route; were it not for this 
the fertilizing mechanism would be but seldom utilized, as the 
humble bees could reach the nectar without poking their heads 
between the sides of the hood. Ants and other undesirable visi- 
tors are excluded by long hairy trichomes pointing outward. 
There is a point in the structure of the flowers of 2 canaden- 
sis of which I find no mention as occurring in the European spe- 
cies. It is the curvature of the hood of the corolla; a device 
which materially aids the bee in reaching the nectar. Supposing 
a person standing with his back to the stem of the plant, the 
hood, in the great majority if not all cases, curves to the left. In 
l instances observed, the bees took advantage of this and lit 
upon the left. 
e flowers are more largely visited by species of bumble-bees 
(Bombus) than any other insect. It is by them that the most of 
the flowers are fertilized. In one instance observed, a single bee 
visited one hundred and forty-four flowers in succession, and 
er observation convinced me that this was less than the 
usual number visited at one time. As the flowers are arranged 
spirally on the stem of the plant, the bee usually alights upon 
e lower flower and follows the spiral upward. In some cases a 
bee would come to a plant just after another had left it, but would - 
seldom try more than one or two flowers. Finding the nectar 
gone from these, it seemed to realize that all on the plant had 
been plundered, and left for greener pasu res s 
e next most numerous visitors are butterflies of the family 
Hesperidæ, which during the later portion of the flowering sea- 
son visit it freely. It is doubtful, however, to what extent they 
aid in fertilization, as in many cases they do not bring the fertili- 
zing mechanism into use. The same doubt exists as to the fer- 
tilizing benefit of the humming birds which visit it to a ag 
extent, Probably in the case of the latter the prickly areal 
ers are of but little use. Besides the Hesperide a few Cai 
lodice were observed. , isd 
In the Popular Science Review for 1870, p. 41, Dr. Ogle e 
ibes the manner in which humble bees rob the pim of the 
cow-wheat by biting through the calyx, and adds; “The very 
