Fig. 16. Fig. 17. Fig. 18.
[Fig. 26] ([page 141]) represents the crystal when complete; the drawing was made by ourselves, and gives with great exactitude the figure of the needles, which, it will be observed, diverge from the main stem uniformly at an angle of 60°. The position maintained by them around the centre of the crystal is beautifully adaptive, and well worth examination.
It is not always that the primitive spiculæ are divergent in groups of six. At times they arrange themselves irregularly in clusters, and crystallization proceeds with results of a character
Fig. 19. Fig. 20. Fig. 21.