CALCAREOUS SKELETON OF THE ANTHOZOA. 545 



PLATE 41. 



Figs. 13 — 25. — Heliopora cocrulea, Pallas, ca. Calicoblast. ca. i. 



Internal layer of calicoblasts. ca. e. External layer of calicoblasts. iiij. 



Alesogloca. en. Endoderni. dc. Desmocytc. ov. Ovoid bodies, zo. 

 Zooxanthetiiv. 



Fig. 13. Portion of a section tlirougli the growing point of Heliopora, 

 showing the external and internal calicoblast layers, m. I. Limiting 

 membrane formed outside the internal calicoblast layer. Zeiss, -^^ 

 horn, inim., c. oc. l. 



Fig. 14. Ovoid bodies, showing nuclei and vacuoles. 



Fig. 15. Early stages iu the formation of dcsmocytes. A striated body, 

 stained blue by picro-nigrosin, is contained within a much vacuolated 

 cell. 



Fig. 16. Further stages in the development of desniocytes. 



Fig. 17. A desmocyte is becoming attached to the mcsogltica by a 

 process, p. m. I. Limiting membrane. 



Fig. IS. Uesmocyte iu course of formation, attached by several bands to 

 the mcsoglaa. 



Fig. 19. A fully formed desmocyte, showing the characteristic cupped 

 shape, m. I. External limiting membrane. 



Fig. 20. A group of calicoblasts, some of which arc undergoing dis- 

 integration. 



Fig. 21. Calicoblasts stained with cosin, showing the cosinophilous 

 granules, gr. ci\ys. f. Groups of crystalline fibres adherent to a mesh- 

 work of organic lilamcnls. Zeiss, ,\ lioni. iinni., c. oe. i. 



Fig. 22. Growing edge of a eivneneliymal spine, showing the manner lu 

 which it is built up of numerous crystals. Zeiss D, oc. 4. 



Fig. 23. Surface view of jiart of a partition wall of a cocncncliynial 

 tubule from the growing edge of Heliopora. The component crystals 

 are arranged pell-mell in no dt-linite order. Zeiss D, oc. 1. 



Fig. 21. Isolated crybtaliine elements from the same preparation as 

 Fig. 23. Zeiss, ^^ horn, imni., c. oc. 4. 



Fig. 25. Portion of a transverse section taken about 2 mm. below the 



growing edge of a frond of Heliopora. a. a. Centres of calcilicatioii, 



from which crystalline fibres diverge to meet those of adjacent systems 



at the sutures h. h. ct. Ccenenehymal tubes. 



Fig. 26. — Surface view of the flattened endoderm cells forming part of the 



investment of a septum of Caryophyllia Smithii. f. Flagella, each arising 



from a clear space closely contiguous to the nucleus. The clear spaces are 



iu the centres of small asters, and apjjcar from their position to be related to 



the ecutrosome. The astral rays were stained as figured by safranin, but the 



fligella arc represented in red only for clearness' s;ike. 



