The author, continuing the experiment of spring and autumn, had an experiment on the changes by death, of the vegetative Plankton (diatoms) in the organs of drowned bodies in summar, and has obtained the following results: 1. There were 11 diatoms from the water of the river as well as the experiments of spring and autumn. 2. There were 8 among 11 kinds of diatoms which were found in the lung for three days after death, the utmost limited time for use. 3. There were 3 among 11 kinds of diatoms which were found in the heart, liver and kidney for three days after death, the utmost limited time for use, they are Cymbella parva, Melosira islandica and Cyclotella comta which have been considered to have strength for resisting to decomposition. 4. Among these 11, 5 diatoms such as Cymbella parva, Navicula radiosa, Melosira islandica, Cyclotella comta, and Rhopalodia giba were found in the femur even two months after death. 5. From the experiment above, the author has come to the conclusions. In summar when the progress of decomposition is quick, the organs of drowned bodies melt and it is for use, the diatoms stay in the femur for the long term; this can be said to be the basis in the explanation whether drowning is the cause of death.