587 
There is little doubt that the wind exerts a great influence upon the 
‘fertilization of some of our cereal crops, though botanists are not unan- 
imous on this point. It would appear from recent researches on this 
subject (see Monthly Report for May and June) that some of the grains 
are subject to close-fertilization, and others to cross-fertilization, in either 
ease the occurrence of violent storms of wind or rain at the season of 
flowering might operate injuriously upon the fertilization, and thus jus- 
tify the anxiety which farmers are said to possess as to the occurrence 
of favorable weather at this season. 
In the majority of flowers, however, the structure of the pollen, or the arrangement 
relative to one another of the pistil and stamens, is such that fertilization could not be 
.effected by the wind alone. Sometimes the pollen-grains themselves are too large and 
heavy to be thus conveyed, or they are united together by fine threads or even in 
dense masses; or the position of the stigmatic portion of the pistil is evidently not 
adapted for the pollen to reach it in this way, and nature then employs as the agent in 
fertilization insects or other small animals.; This opportunity is afforded by the visits 
of insects to the flowers in search of the honey, or nectar, which forms an important 
portion of the food of many classes. The mode of attraction to the flowers which serve 
them as food is mainly two-fold, scent and color. 
Nature is always economical of her resources, and accordingly we do not generally 
find that strong scent and brilliant variegation of color are bestowed on the same 
flower. Those which are most prized for the power or delicacy of their scent, have, as 
a rule, flowers either inconspicuous or, if large and conspicuous, of uniform unvariegated 
color; as, for instance, the mignonette, primrose, sweet violet, lily of the valley, honey- 
suckle, linden, and many others, while the most brilliantly variegated flowers are com- 
paratively or quite scentless, as the fritillary, Pelargonium, Tropeolum, Mimulus, Ranun- 
-culus, pausy, &c. 
One of the largest of scented flowers, the evening primrose, blossoming only in the 
night, is fertilized by night-flying moths, which probably require the large sulphur- 
yellow flowers, as well as the scent, to guide them from a distance in the dim light. 
American naturalists state that many of the largest and most gorgeous flowers of the 
western continent, such as the Bignonias, or trumpet-flowers, are fertilized by hum- 
ming-birds. Another mode in which insects assist in the fertilization of flowers is by 
‘the voluntary deportation of pollen; and this is chiefly effected by Hymenoptera be- 
longing to the class Aphidw, which includes the hive and humble-bees that build nests 
in which they store up large quantities of food for their young while in the larva state. 
This bee-bread, as it is termed, with which the thighs of homeward-bound bees are 
seen to be heavily laden, consists almost entirely of innumerable pollen-grains robbed 
from the flowers, which the little depredators may be seen to despoil in a very scien- 
tific manner. Though the greater quantity of this pollen is carried home, small quan- 
tities of it are unavoidably left behind here and there on the stigmas of the flowers, 
quite sufficient to ensure the fertilization of the ovules. 
We mentioned at the outset that though the large majority of flowers are cross- 
fertilized, yet there are exceptions to the rule. There are not a few flowers which 
never or scarcely ever completely open their petals so as to allow either the entrance 
-of an insect or the escape of the pollen. 
In many plants belonging to widely separated natural orders, either intermixed with 
the ordinary conspicuous flowers, or appearing at a different time of the year, there 
are peculiarly-shaped flowers, called cleistogamous, which are self-fertilized. Among the 
natural orders in which these flowers have been found are Violacew, Cistacew, Oxali- 
dacee, Balsaminee, Polygalacee, Caryophyllacew, Leguminose, Campanulacee, Convolvu- 
lacew, Acanthacec, Labiatw, and Commelynacee. The two species of Impatiens or Touch- 
me-not, which grow wild in this country, Impatiens Noli-me-tangere, and I. parviflora, as 
well as a North American species, J. fulva, which is fully naturalized in some places, 
have closed, imperfect, self-fertilized flowers intermixed with the showy yellow ones. 
The most easily observed instances are, however, in the case of our common wild 
violets, the sweet violet, (Viola odorata,) or the various forms of the dog violet, ( Viola 
canina.) The existence of these flowers in Viola was known as long ago as the time of 
Linnzeus, who states that the flowers of Viola mirabilis produced in the spring are often 
barren, while the later ones, which have no corolla, are fertile. The cleistogamous flow- 
-ers of the violet appear long after those that are familiar in the spring, and may be 
found in abundance in July and August, very small, but still not difficult to make out. 
These closed summer flowers produce an abundance of seed. In accordance with the 
ordinary practice of economy by nature, the amount of pollen in the cleistogamous 
flowers is generally very much less than in the open ones, since it has very little 
‘chance of being wasted. 
More detailed examination of these closed flowers in different plants will doubtless 
yield interesting and important results. 
