细胞学家。浙江镇江人（今宁波市）。1921年毕业于同济医工专门学校医预科。1928年获德国土滨根大学自然科学博士学位。中国科学院生物物理研究所研究员、名誉所长。在丰年虫中间性的性转变过程中，观察到细胞重建现象；对鸡胚早期发育、小鼠造血系统（骨髓）、根瘤菌和沙眼衣原体进行了细胞重建的研究；特别是在丰年虫和鸡胚早期发育中，证明以卵黄颗粒为基础或细胞质为基地，重建为细胞，是客观存在的现象，并从卵黄颗粒中提取出染色质。早年对线虫生活史、个体发育、细胞常数、再生、染色体结构和行为，甲壳动物色素细胞在不同温度和不同浓度眼柄激素影响下的活动情况，摇蚊幼虫变态过程中咽侧体和心侧体结构与功能变化以及环节动物再生、再生与自然分裂关系、不同温度下分裂与解体关系进行了研究。

1955年被选聘为中国科学院院士（学部委员）。

Cytologist. Born in Zhenhai, Zhejiang Province, Graduated from the premedical course of Tongji Medical and Tcchnical College in 1921. Received Sc.D. from Tuebingen Uneversity, Germany in 1928.Research professor and honorary diredtor, Institute of Biophysics,Chinese Academy of Sciences.

During the intersex changing of Chirocephalus, Bei observed the phenomenon of cell reformation and investigated cell reformation in early development of chick embryo, hemopoietic system of mice (bone marrow), nodule bacteria and Chlamydia trachomatis. He proved that the existence cell reformation is an objective reality, especially in the yolk granules and cytoplasm of early development of Chirocephalus and chick embryo and extracted chromatin from yolk granules.Formerly, he studied the life history, development, cell-constancy,regeneration, structure and behavior of chromosomes of nematode. He also studied chromatophore activity of crustacean in relation to different temperature and different concentrations of Eyestalk-extract, structural and functional changes of Corpus allatum and Corpus cardiacum of Chironomus larvae during metamorphosis, and annelid regeneration,relation between regeneration and natural fission, relation between fission and disintegration at different temperatures, etc…

He became Member of the Chinese Academy of Sciences in 1955.