在初一生物（上）实验七中，有观察《叶片的结构》的分组实验，其中有观察叶的下表皮结构内容。书中指出可用蚕豆叶片做实验材料，原因是蚕豆叶片下表皮气孔多，但由于蚕豆叶片薄，下表皮不易撕下，对于初一学生来说，操作有一定困难。我们通过几年的教学实践证明，以下两种材 In Experiment No. 7 (above) Experiment No. 7, there were grouped experiments for observing the structure of “leaves,” which included observing the contents of the lower epidermis structure of the leaves. The book pointed out that it can be used as an experimental material for broad bean leaves. The reason is that there are many stomata in the lower epidermis of broad bean leaves. However, due to the thin leaves of broad beans and the lower epidermis is not easy to tear off, it is difficult for junior students to operate. We have proved through several years of teaching practice that the following two materials