This report is intended to simplify the window method for observation of the development of chick embryos. The pointed end of the eggshell was cut off 3 cm in diameter. The open end was covered with transparent wrap film, such as polyethylen wrap. The film was fixed with a hold-ring. The other hold ring was set at the opposite end of the eggshell. Both hold rings were held together with four rubber bands. Main points of improvement were as follows: 1) the eggs with the window were incubated in the plastic box on the shaker at 60 rpm at 38°C The humidity was supplied from the water in the plastic box, and fresh air was introduced into the plastic box by an air pump. 2) About 4 ml of the albumen was discarded from the eggs the third day after incubation. Then the eggs were incubated at 50 rpm at 38°C for 15 more days. Using this simplified window method, about half of the eggs developed for 18 days, which was 3 days before hatching. Possible application of this method to elementary and high school biological education was discussed.

An area for observation was set up on a plot of land (1m × 2m) atrificially denuded in a field at the Chiba College of Health Science (Chiba City). The early stage processes of secondary succession have been observed there for nearly 11 years. It was observed that in the first three years after denuding, the plants which formed a plant community in the plot changed gradually from annual to perenninal types, and that in the tenth year a tree began to put forth its blossoms and bore fruits.

The results of the observation showed that when a plot of land in the college field was denuded, the early stage processes of secondary succession took place there more quickly than expected. also, when two plots of land are denuded at different periods, different stages of succession could be observed at the same time.

The fact that the vegetation in the plot changed from annual to perennial types in the first three years after denuding, indicates that the denuded plot is useful for ecological study in school. The results presented here and in similar studies are valuable for students to construct the concept of secondary succesion in high school biology.