Is it dividing?
Several sizes of diatoms are living in Hirose River. This is one of the largest, and we can see two cells are surrounded by a membrane. Each cell is covered with a hard siliceous cell wall. The two cells may be in the process of division. Larger brown structures as well as small particles are moving inside the cytoplasm of the diatoms.
Commentary by Prof. Yuji Tsukii, Hosei University
The yellowish-brown structure in one of these diatom cells may be a chloroplast losing its shape.
The organism seems not to be in the process of division, rather already dead. If the organism is alive and dividing, the brown structure (chloroplast) should be equally spread in both cells.
We cannot see one of them, and the remaining one is shrinking. These show that both cells are alreday dead.
This diatom may be in the genus Surirella.
Sampling Date : 03 July 2009
Sampling Site : Hirose River B Google Map