530 GILBERT C. BOURNE. 



bourhood of the nucleus. On focussing carefully the promi- 

 nence exhibits radial striae, as shown in the figure, surrounding 

 a central clear space, and the flagellum seems to end in a 

 minute granule in the midst of the clear space. The cytoplasm 

 of the cells is much vacuolated, but usually there is a mass of 

 deuser protoplasm round the nucleus in which the star-shaped 

 structure is situated. The invariable proximity of the star- 

 shaped body to the nucleus suggests that the flagellum is con- 

 nected with the centrosome. If this is so it has the same 

 relations as the flagella of the spermatids of Elasmobranchs 

 described by J. E. S. Moore. I was unable to find any example 

 of these cells in course of division. 



These endoderm cells are placed upon an exceedingly delicate 

 lamina of mesoglcsa, so delicate that it is easily overlooked, 

 but it may be made evident by picro-nigrosin. On the other 

 side of the mesogloea — that is to say, next to the corallum — are 

 a number of nuclei, round and clear in appearance, staining 

 with great difficulty, and showing no chromatin network, but a 

 single nucleolus. 



Surrounding each nucleus is a thin layer of finely granular 

 protoplasm, connected by fine processes with adjoining cells of 

 the same character. This is all that represents the calicoblast 

 layer over the greater part of the corallum, and so thin and 

 delicate is it that it is hardly to be distinguished in transverse 

 sections. But at the edge of a septum, where the sheet of 

 tissue is folded over it, the calicoblast layer in the angle of the 

 fold assumes more definite characters. It is still exceedingly 

 thin, but the cytoplasm surrounding the nuclei increases in 

 bulk, and exhibits a distinct vesicular structure in addition to 

 the coarser vacuoles which are abundantly developed in it. 

 The nuclei also show chromatin networks. Sections made 

 through a Caryophyllia which has been killed in a mixture of 

 8 per cent, formol in sea water, to which is added about 3 per 

 cent, of saturated solution of corrosive sublimate, and after- 

 wards carefully decalcified in weak acetic acid, show the same 

 results, and also that the calicoblast layer is more definite in 

 the immediate neighbourhood of the mesenteries, both in the 



