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为了便于考过的同学认证 我copy出来了 谢谢楼主啊 非常感谢 嘿嘿
Blaustein and his colleagues tested whether or not UV-B could be a factor in lowering the hatching rate of amphibian eggs. At two field sites, they divided the eggs of each of three amphibian species into three groups (Figure 3.6). The first group developed without any sun filter. The second group developed under a filter that allowed UV-B to pass through. The third group developed under a filter that blocked UV-B from reaching the eggs. For Hyla regilla, the filters had no effect, and hatching success was excellent under all three conditions. For Rana cascadea and Bufo boreas, however, the UV-B blocking filter raised the percentage of eggs hatched from about 60% to close to 80%.
The environmental programs of experimental embryology were a major part of the discipline when Entwicklungsmechanik was first established. However, it soon became obvious that experimental variables could be better controlled in the laboratory than in the field, and that a scientist could do many more experiments in the laboratory. Thus, field experimentation in embryology dwindled in the first decades of the twentieth century (see Nyhart 1995). However, with our increasing concern about the environment, this area of developmental biology has become increasingly important. Other recent work in this field will be detailed in Chapter 21. |
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发表于 2010-10-26 07:18:34
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