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ANNALS NEW YORK ACADEMY OF SCIENCES 
cation, in 1862, of liis book on that subject, and in it his detailed observations 
are recorded. Some of his closest observational work was done on this 
subject of cross-pollination, and he examined a great many species and 
grew thousands of plants from seed, reaching the broad generalization that 
cross-fertilization is beneficial to a species and self-fertilization is injurious. 
The phenomena do not now, however, appear to have as important a relation 
to evolution as they were formerly supposed to have, and Darwin later 
expressed regret that he had not given more attention to the processes of 
self-fertilization. 
His interest in showing that cross-fertilization was beneficial led him to 
investigate closely the various structural features of flowers which necessitate 
this process to a greater or less degree, such as dioecism, monoecism, poly¬ 
gamy and heterostyly; his observations and speculations are presented in 
the volume entitled “Different Forms of Flowers and Plants of the Same 
Species,” published in 1877. He records that making out the meaning of 
heterostyled flowers gave him very great pleasure. A chapter of the book 
is devoted to eleistogamic flowers, which are necessarily self fertilized and 
produce seed abundantly. This work is largely a revision and rearrangement 
of several papers previously published in the Journal of the Linnoean Society. 
“The Variation of Animals and Plants under Domestication,” Darwin’s 
largest work, appeared in 1868, published in two volumes. As bearing on 
this topic, he had studied, among plants, for many years, the cereal grains, 
garden vegetables, edible fruits, ornamental trees and ornamental flowers. 
In the preface he again discusses natural selection and defines it as “This 
preservation, during the battle for life, of varieties which possess any ad¬ 
vantage in structure, constitution or instinct,” noting that Herbert Spencer 
had well termed the same process “The Survival of the Fittest.” But the 
bulk of the work is given to the consideration of selection by man — arti¬ 
ficial selection, by which races useful to us, economically or esthetically, 
have been preserved and modified, some of them having originated in very 
remote times and been taken advantage of by uncivilized man. A chapter 
is devoted to the phenomena of bud-variation, in which many cases of 
branches of plants different in one respect or another from other branches 
on the same plant are described in detail. Many of these have been taken 
advantage of by horticulturists for the propagation of valuable races. He 
did not reach any definite conclusion as to the cause of these interesting 
occurrences; but recently acquired knowledge of mutation seems to indi¬ 
cate that they are of that category, differing from seminal mutations in 
that a cell in the axil of a leaf is affected rather than a germ-cell. In these 
volumes we find Darwin’s most detailed discussion of heredity, of variability 
and of hybridism and the last chapter outlines his provisional hypothesis 
