[188] It is a matter of regret to the writer that owing to the long distance intervening and the difficulty of securing competent and sympathetic observers for such work, it has not been possible for him to secure photographs of the tree-forms here discussed. At the time his own observations were made, photography was practically unavailable as yet, and the figures given are therefore based upon sketches made at the time, and partly upon recollection. They represent types rather than definite individuals, which were however described when fresh in mind, in the Report on the Agriculture and Geology of Mississippi, 1860, pages 254 et seq.
[189] It has been already, and doubtless will be again and increasingly, attempted to make distinct “species” of these widely different forms of trees. But this is simply begging the question. Mere external diagnostic marks will not avail here; it would have to be shown that the seed of these different forms do not produce the other forms under changed conditions. Until this has been done, the number-less transition forms which he that runs may observe in the field, throw upon the species-makers the onus of proof of differences of specific value—if it be possible to define such value.
[190] Rep. of Geological Reconnaissance of Louisiana; New Orleans, 1873, p. 27.
[192] Hence perhaps the vernacular name “gumbo” for heavy, adhesive clay soils in the north central states; which may also, however, be derived from a comparison with the “gummy” pods of the cultivated okra or gumbo plant.
[193] See Plant Life of Alabama, by Charles Mohr, Vol. VI. Contr. U. S. Nat. Herb., U. S. Dep’t Agr.; Alabama Ed. of Same, Ala. Geol. Survey, 1901.
[194] See “Final Report of a Geological Reconnoisssance of Louisiana,” published by the New Orleans Academy of Science in 1871.
[195] In view of its specific designation and the reputed poverty of New England soils, this is rather unexpected.
[196] Essai de Phytostatique appliquée à la chaine du Jura et aux contrées voisines. 2 vols. 8vo. Berne, 1849.
[197] Annales de Chimie et de Physique, 4me série, tome 29; ibid. 5me série, Tome 2. Also, ibid, tome 18, 1879.