Hayes and Garber - Cucurbit Breeding

INTRODUCTION 9
strengthened and developed. Likewise, without use it was weakened.
The supposed inheritance of these acquired characters
was the basis of the production of the numerous species.
The term species was first applied to animals and plants by
John Ray (1628-1705) who used it to refer to a group of organisms
with similar characteristics and which freely intercrossed.
Many of
the experiments of this period dealt with the question
of species.
The Doctrine of the Constancy of Species. Linnaeus (1707-
1778) adopted a more strict definition although he was not always
consistent in his use of the word. The doctrine adopted was that
of the separate creation of fixed entities which were called species.
Lamarck denied this theory and outlined his evolutionary
hypothesis. Most naturalists of this period believed in the
immutability of species.
It is thought that the work of Lyell (1797-1875), an eminent
geologist, had a marked effect on that of Charles Darwin, who was
his intimate friend. Lyell insisted upon the continuity of the
earth's history and the uniformity of agencies which wrought
such profound changes upon the earth. This theory was in
opposition to that of Cuvier, who believed that the earth's history
was a series of times of destruction followed by periods of tranquillity
("catastrophism"). After each such destructive period
it was believed that new creation took place.
Darwin's Theory of Natural Selection. The most influential
worker in the history of development of the evolutionary conception
was Charles Darwin. He and Alfred Russel Wallace
independently developed a theory for the origin of species and
united in presenting a preliminary paper in 1858.
The publication of Darwin's " Origin of Species" in 1859
gradually brought about a belief in evolution. The work of Lyell
had helped materially to develop a belief in the orderly progress
of the world and assisted in preparing the way for the masterly
presentation of Darwin. Darwin presented such a mass of
evidence from widely different fields that the entire thinking
world was compelled to accept evolution as a fact. The evidence
was grouped under such headings as organic relationship, comparative
anatomy, embryology, paleontology, and domestication.
The fact of evolution is indisputable. The explanation
is even yet not entirely satisfactory. Darwin's theory is founded
upon a series of facts as follows :