Items related to Botany for agricultural students
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1919 Excerpt: ... reveals. Scientists believe that the living forms have come from previously existing forms and hence are related through a common ancestry. They have originated through the process known as evolution, which assumes that the first plants on earth were extremely simple and from these simple forms the more complex forms arose. In response to a changing environment or due to changes arising wholly within, the simple forms gave rise to more complex forms, which in turn gave rise to forms still more complex. Thus through slow changes involving millions of years the highly developed forms were evolved. Evolution has generally been progressive, giving rise to forms with higher organization, greater perfection of parts, and increased efficiency of function. Sometimes, however, evolution has been retrogressive, and forms have been reduced to simpler forms, through becoming more simply organized and less efficient in function. For example, in this way the Fungi are supposed to have arisen from the Algae. Progressive evolution has not been direct from the simplest to the highest organisms, but has been along many lines which, although usually progressive, have been more or less divergent and this accounts for many kinds of organisms among both plants and animals. Animals and plants can be distinguished in their higher forms on the basis of locomotion, methods of getting food, character of the skeleton, and so on, but in their simpler forms animals and plants are not easily distinguished, and this fact suggests that plants and animals arose as diverging lines from the same preexisting organism. A diagram of evolution in plants looks like a tree with many branches. The trunk represents the main line and the branches the diverging lines of evolution. The lowest branches ...
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- PublisherRareBooksClub.com
- Publication date2012
- ISBN 10 1151927430
- ISBN 13 9781151927439
- BindingPaperback
- Number of pages170
(No Available Copies)
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