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JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



of the inheritance of acquired somatic characters, experiments are not 

 wanting to show what are the causes which have brought about the 

 natural peculiarities of wild plants growing in distinct environments. 

 Thus M. Lesage has proved by experiments that the fleshiness of so many 

 maritime plants, as the Samphire, is directly due to salt. 



M. Bonnier, by cultivating lowland plants at Paris, &c, upon high 

 altitudes in the Alps, proved that they all more or less acquired the dwarf 

 form and peculiar anatomical structure of the leaves, &c, characteristic of 

 alpine plants, as well as the intensified coloration of their flowers. 

 Conversely, normally high alpine plants cultivated at low levels did not 

 change so rapidly, but required some years to do so. 



M. Eberhardt carried out experiments to contrast the effect of an 

 excessively dry air with those of a very moist one. The results were 

 that the external forms and internal anatomy agreed precisely with those 

 of dry alpine desert plants, and other localities noted for drought, on 

 the one hand, and with the anatomical details of plants growing 

 normally in very moist situations on the other, the structure of the latter 

 being in the same direction as the anatomy of aquatic plants. Lastly, to 

 test the question whether the finely dissected type of leaf in submerged 

 dicotyledonous plants was due to the water, Mr. McCallum experimented 

 with Proserpinaca palustris, a plant of the United States, which bears 

 fully developed leaves in air, but dissected ones under water.* 



Assuming, as a "working hypothesis," that the submerged leaves 

 owed their forms to a surcharged protoplasm, which, by being saturated 

 with water, was too weak, so to say, to produce full-sized leaves, he charged 

 the water with certain nutritive salts. This set up osmotic action in the 

 plant, and withdrew the excess of water from the protoplasm ; whereupon 

 the plant forthwith formed full- sized leaves under water. 



We have thus now an abundance of proofs, both by induction and 

 experiment, that the form and structure of the organs of plants are due to 

 the immediate response of the living protoplasm to the influences of the 

 environment, and that it, or rather the nucleus, builds up just those cells 

 and tissues which are in adaptation to the conditions of life. Then, after 

 a few years, they become hereditary and so fix the varietal or specific 

 characters by which botanists recognise and distinguish plants in nature. 



Whenever these specific characters arise in the vegetative organs, they 

 have been acquired by them, i.e. the soma, long before any reproductive 

 organs were in existence, and therefore before germ-plasm could be 

 present — at least, presumably in sufficient quantity to receive impressions 

 from without ; unless, as already stated, it be as universally distributed 

 through all the vegetative organs as protoplasm itself. But this suppo- 

 sition at once does away with the necessity for it, for protoplasm and the 

 nucleus are quite able to do all the work required. 



If it be further asked, " How can any impression be conveyed from the 

 circumference, where it is received from external impulses and irritations, 

 to the embryo-sac ? " the reply seems to be that it may be conveyed thereto 

 by protoplasmic continuity. There is at least a machinery which it is con- 

 ceivable may be capable of conveying vibrations to the germ-cells when 

 these latter come into existence. But as to the nature of this inherent. 

 * Botanical Gazette, xxxiv., Aug. 1902, p. 93. 



