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AGENCY OF INSECTS IN FERTILIZING PLANTS. 
BY W: J. BEAL. 
Mr. CHARLES Darwin and other botanists have proved 
beyond a doubt, that some flowers, in which the pollen 
may easily gain access to the stigma of the same flower, 
are sterile unless fertilized by pollen borne from other 
flowers, while many are much more productive by a cross 
fertilization. 
For information concerning the peculiar manner in 
which fertilization is effected in the Balsam, Wood-sorrel, 
Violets, Dicentra or Dielytra, Corydalis, } Mitchella or 
Partridge-berry, Oldenlandia or Houstonia, Primrose, 
Barberry, Lysimachia or Loosestrife, Orchids, Dutchman’s 
Pipe, and others ; consult the. observations recorded by 
Mr. J.T. Rothrock in the second number of the NATURAL- 
ist, Mr. Darwin’s work on the “Fertilization of Orchids,” 
and seven articles by Dr. A. Gray in the “American Ag- 
riculturist,” beginning in May, 1866. 
With the fact that insects are necessary to fertilize some 
plants, and the theory that all are improved by crossing, 
let us see how this is accomplished in plants which may 
not seem to require the aid of the wind or insects. Plants 
are very rarely found in which the pollen may not, occa- 
sionally at least, get to the stigma of another flower of the 
same, or an allied species. Then if the pollen is “pre- 
potent” or most effective on stigmas when thus transferred, 
a cross is very sure to result, even though much pollen 
comes in contact with the stigma of the same flower. Dr. 
Gray, acquainted with hoier facts, and familiar with the 
structure of the Iris, saw that insects must be needed for 
: the fertilization of this plant also, and without seeing the 
Ip , shrewdly pointed out the manner in which 
