以前作此实验多采用女贞,但效果不理想,近两年来,我改用叶球甘蓝作实验材料,效果较好。具体作法是: 课前半天从地里采回甘蓝,削去根部,剥除老叶,露出白嫩的叶,随即将此叶球甘蓝的茎插入盛有红墨水的容器中。上课时即可看到叶球呈猪肝色,近看,叶表有许多如毛状“毛细血管”即被染红的导管。横切叶 In the past, we used privet more for this experiment, but the effect was not satisfactory. In the past two years, I switched to Cabbage for experiment, which is better. The specific practice is: half a day before the class back to take the cabbage from the ground, cut off the roots, stripped of the old leaves, revealing white and tender leaves, then the cauliflower stem into the container filled with red ink. You can see the ball was pig liver color during the class, near the leaf table, there are many, such as hair-like “capillaries” that is dyed catheter. Cut the leaves