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the sex organs in different flowers on the same growth. In the great 
majority of instances both organs are found in the same flower. No 
matter what the arrangement may be it is absolutely necessary that 
the pollen grains from the anther or the male part of the blossom reach 
the pistil, the female part of another. In some flowers the anther 
reach maturity and throw out the pollen before the seed chamber is de- 
veloped or the stigmas receptive. In the willow bush we find a good 
example of this condition. In other plants the pistils mature before 
the anthers ripen as in the common figwort and the horse chestnut. 
Again we have flowers whose anthers and pistils mature at the same 
time, but because of their relative position self-fertilization is impos- 
sible. Other arrangements might be mentioned showing the impos- 
sibility of self-fertilization and nature’s demand for cross-breeding. 
All of this also tends to confirm the popular belief in the danger of 
close in-breeding in animals as well as in plants and the desirability 
of cross-breeding in stock and cross-fertilization in plant life. 
Fic. 583—Perrecr PoLLinaTION Fic. 54—IMpPErFect POLLINATION 
A German writer by the name of Sprengel published a book in 
1793 on “The Secret of Nature in the Form and Fertilization of Flow- 
ers Discovered,” in which he claimed the independent creation of 
species through self-fertilization. Later on other investigators reach- 
ed different conclusions; among them was Andrew Knight, whose ex- 
periments proved to him that in no plant does self-fertilization occur 
for an unlimited number of generations. It was not until after the 
appearance of Darwin’s “Origin of Species” that Knight’s theory was 
emphasized in a general law of nature. In Darwin’s second work, en- 
titled “Various Contriyances by Which British and Foreign Orchids 
Are Fertilized by Insects,’”’ he sums up his work by stating that “Na- 
ture abhors perpetual self-fertilization.” ; 
The pollination or fertilization of plants is brought about in two 
ways: first, by the wind; second, by insects. Plants whose flowers 
are small and inconspicuous, as the willows, pines, oaks and birches, 
