“观察植物细胞有丝分裂”是高中生物的一个重要实验。通过实验,学生对细胞分裂的过程和染色体的概念有了一个感性的认识,初步掌握了制作洋葱根尖有丝分裂装片的技术和绘制生物图的方法。但该实验如果按照教材中洋葱根尖的培养方法,药品浓度的配制,以及实验步骤中的操作过程,要想获取较好质量和数量的洋葱根尖是很难的,而且实验的成功率较低,实验现象也不明显。在多次实验摸索后,笔者发现以下几点尤为重要。一、实验材料的选择按课程进度该实验一般安排在每年的9～10月份。所以6月下旬就要到市场去采购,此时也是采购洋葱的最佳 “Observing plant cell mitosis” is an important experiment in high school biology. Through experiments, students have a sensible understanding of the process of cell division and the concept of chromosomes. They have mastered the techniques of preparing the root tip mitotic patch and the methods of drawing biological figures. However, according to the teaching method of onion root tip training methods, the preparation of drug concentration, and the experimental steps in the process of operation, in order to obtain better quality and quantity of onion root tip is difficult, and the success rate of the experiment Low, the experimental phenomenon is not obvious. After many experiments to explore, I found the following points is particularly important. First, the choice of experimental materials according to the progress of the course The experiment is generally arranged in the 9 ~ October each year. Therefore, it is necessary to go to the market in late June to buy at this time is also the best procurement of onions