



fciiv* 





4# 





7. Photomicrograph. Embryo 409 ( /6 mm.). Cross-section 10-2-5. X 10. This figure illustrates the symmetrical positions occupied 



by the lateral (c /) and mesial (c m) cavities. Larger reproductions of them are shown in Figures 8 and 9. 



8. Photomicrograph of the cavum mediale corporis striati. X 200. The smooth-walled space is parked with macrophages. An engorged 



blood-vessel (b v) forms its lateral boundary. The position of this illustration is indicated in Figure 7. 



9. Photomicrograph of the cavum laterale corporis striati X200. Some of the nerve-cells are growing across the cavity. The position is 



shown in Figure 7. 



10. Photomicrograph of a section through the corpus striatum of a chicle (121 hours incubation). X 7'<. The cavities (<: s) in the 



striate body are unusually large. 



11. Geometrical projection of a model made at 50 diameters. Embryo 460 (21 mm.). X6J£. The cavum laterale (c / ) and cavum 



mediale (c m) are shown on the right side. 



12. Macrophages indicated in Figure 6 X 1000. (Drawn by J. F. Vidusch.) 



