Abstract:
[a] Experimental Taxonomy.
The process of evolution will not be fully understood until the nature and causes of organic variation are known. The importance thus assigned to the variation of taxonomic entities would find favour with most botanists of the post-Darwinian period, but one has only to refer to the writings of the early 19th. century to find a very different attitude prevailing. At this, and earlier times, the different "kinds" of organisms were regarded as clearly delimited, unchanging entities which came into being as a result of separate acts of creation. Linneaus writes--"Species are all those diverse forms which the infinite being produced in the beginning. Each of these forms has produced, in accordance with the laws of generation, more like unto itself. Hence there are as many species as there are at the present day different forms and structures." It was not until Darwin's theory of evolution, published 1859, that this belief in "the constancy of species" was seriously questioned and the problem of variation fully disclosed. This change in outlook was largely due to Darwin's basic claim that present biological entities are not unchanging units but are merely stages in a continuing process. In the years that followed, this new concept had a gradually increasing influence in all fields of Botany. Morphological facts were described and compared from this point of view, and by the end of the century a general scheme of evolution for the kingdom had been postulated.
