Plate 8, Figs. 15 and 16 are two of the experiments made in the month of April,1927. In Fig. 16 the photograph has been taken after the forms had fully matured,in Fig. 15 the photo was taken at an earlier stage; thus, we still can see the subtle radiating structure, although the forms which will appear later are already faintly indicated. Compared with the previous month, it seems as if the forms are more powerful.