Abstract: In the karyotype of Paris cronquistii,the variations of chromosome structure and a series process of B-chromosomes produced by break kage of secondary constriction of satelite chromosome were found.These interesting phenomena were received by observation of experiment. The occurrence,accumulator and transmittal of B-chromosome are discussed in this paper. The author recognizes that the breakage of secondary constriction of satelite chromosome has relation to origin of B-chromosome.

Key words: P.cronquistii

摘要： 对同一居群不同个体的凌云重楼（Paris cronquistii)的染色体进行了观察，发现核型结构和B染色体有一系列的变异。据此，作者对其B染色体的起源进行了分析，认为凌云重楼的B染色体是随体在次缢痕处断离后衍生。

关键词: 凌云重楼, 核型, 细胞型, B染色体起源