Cytological Studies on Spirogyra I

1. In this report, a cytological study was made on six species of Spirogyra. Their chromosome number were as follows:Species name Chromosome numberSpirogyra teodoresci 2S. weberi 2S. cylindrica 2S. setiformis 4S. peipingensis 4S. fluviatilis 242. The chromosome number n=2 of Spirogyra teodoresci, S. weberi and S. cylindrica is the lowest chromosome number which is observed for the first time. The basic chromosome number of Spirogyra is thought to be x=2.3. In three species of Spirogyra which have the basic chromosome number n=2, there is only one chloroplast band in one cell of gametophyte, and in species of polyploidy n=4 there are more chloroplast bands, i.e. two to six. In the two species having chromosome number n=4, the cell width of the gametophyte and the zygospore size are larger than that of the three species of n=2, but in S. fluviatilis (n=24) they are smaller than that of n=4.