Abstract
The number of chromosomes in Brassica has been reported by several authors. Since 1929 present writers also examined the chromosome number in 13 species of Brassica covering about one hundred cultivated varieties as the aid to the genetical work of the senior author.
The plants that provided the materials were raised from the seeds obtained from home and abroad. The smear method and sometimes the paraffin method were used. In the case of smear methed, the staining of BELLING's iron-aceto-carmine and HEITZ's aceto-carmine with acetic alcohol were used. Staining of the chromosomes was satisfactory with these stains.
For permanent preparations, CARNOY's fluids mostly and in a few cases NAWASCHIN's fluid were used as fixing reagent and HEIDENHAIN's iron-alum haematoxylin as stain.
The different varieties within the same species exhibited invariably an identical chromosome number. The haploid number of chromosomes is given as follows:
Brassica nigra, KOCH 8 Brassica arvensis, RABH. 9
B. oleracea, L. 9 B. campestris, L. 10
B. pekinensis, RUPR. 10 B. chinensis, L. 10
B. narinosa, BAILEY 10 B. rapa, L. 10
B. nipposinica, BAILEY 10 B. alba, RABH. 12
B. juncea, COSS. B. napiformis BAILEY 18
(including B. cernua, HEMSL.) 18
B. Napus, L. 19
