. Genetics in relation to agriculture. Livestock; Heredity; Variation (Biology); Plant breeding. VARIATION 25 (d) Moisture and Plumage Color.—Beebe experimented with the pigeon, Scardafella inca. This species, as found in North and Central America, is very constant in color of plumage, but in the moist tropics the following darker colored forms occur: in Honduras, dialeucos; in Venezuela, ridgwayi; in Brazil, hraziliensis; and these differ in the amount of pigment in the feathers. By subjecting birds of the northern type to an especially moist atmosphere, Beebe caused them to be so influenced
. Genetics in relation to agriculture. Livestock; Heredity; Variation (Biology); Plant breeding. VARIATION 25 (d) Moisture and Plumage Color.—Beebe experimented with the pigeon, Scardafella inca. This species, as found in North and Central America, is very constant in color of plumage, but in the moist tropics the following darker colored forms occur: in Honduras, dialeucos; in Venezuela, ridgwayi; in Brazil, hraziliensis; and these differ in the amount of pigment in the feathers. By subjecting birds of the northern type to an especially moist atmosphere, Beebe caused them to be so influenced that with each new moulting, whether natural or artificially induced, they always de- veloped darker feathers. Thus a wild bird having pigment in per cent, of its area, would have after the second moulting under experimental conditions, 38 per cent, and after the third, per cent. Thus during the experiment the typical form assumed the appearance of the three other forms and finally developed plumage markings which have never been seen in nature. Fig. 8 shows the type form, inca, the three geographical variants, and the darkest artificially produced Fig. 9.—Plants of Scilla, started alike but the pot on the right was kept in a dark room. {From Ganong.) 2. Enviromnent Conditions Development of Inherited Characters.— (a) Light and Metabolism.—In a general sense light conditions life in all normally green plants. It certainly conditions normal development in such plants. Potatoes sprouted in a dark room develop no chlorophyll in the stems and the rudimentary leaves are abortive. In many bulbous plants, however, the influence of moisture and heat are sufficient to induce leaf growth and even development of the inflorescence, but it is all done at the expense of the food stored up in the bulb as is shown in Fig. 9. Digitized by Microsoft®. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readabili
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