The Primary Factors Of Organic Evolution Author:Edward Drinker Cope Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: its parts." On an earlier page of the same chapter, Lamarck thus formulates the laws of organic evolu-. tion, to which his name has been attached. First law. ... more »" In every animal which has not passed the time of its development, the frequent and sustained employment of an organ gradually strengthens it, develops and enlarges it, and gives it power proportional to the duration of its use ; while the constant disuse of a like organ weakens it, insensibly deteriorates it, progressively reduces its functions, and finally causes it to disappear." Second law. "All that nature acquires or loses in individuals by the influence of circumstances to which the race has been exposed for a long time, and in consequence of the influence of the predominate employment of such an organ, or of the influence of disuse of such part, she preserves by generation, in new individuals which spring from it, providing the acquired changes be common to both sexes, or to those which have produced new individuals." We have here a theory of the origin of characters; viz., of the increased development of loss of parts as a result of use or disuse. We have also the theory that the peculiarities thus acquired are transmitted to the succeeding generation by inheritance. The next formal statement of the efficient cause of organic evolution was presented by Messrs. Charles Darwin and Alfred R. Wallace in I859-1 The cause assigned is natural selection, and Mr. Darwin thus states what is meant by this expression in his work The Origin of Species."1 " If under changing conditions of life organic beings present individual differencesin almost any part of their structure, and this cannot be disputed ; if there be, owing to their geometrical rate of increase, a severe struggle for life at some age, season, or year,...« less