on my yesterday's tour with Bernhard I found at least two individuals showing the anomaly of twin-headed cells. This means, that in one half of the cell the apex is doubled. This phanomenon is known from Euastrum didelta, Micrasterias rotata and Micrasterias papillifera, too. It is not known, whether this an genetic defect or an anomaly that occurs during the asexual cell-division.
a) normal form
b) twin-headed cell no. 1:
c) twin-headed cell no. 2:
