ON THE DEVELOPMENT OF TUBULIPORA. 133 



numerous. In the section drawn they form a large axial 

 mass, lying in the solid tissue on the distal side of the brown 

 body. The details of this tissue are not shown, but it does 

 not differ in any essential respect from the similar region of 

 fig. 16. 



Two embryonic cells are seen, the two large nuclei shown 

 to the right of the follicle-cavity probably belonging to the 

 original egg-follicle. While in tlie younger ovicells shown in 

 figs. 14 and 15 the follicle is in the immediate neighbourhood 

 of the brown body, it is here separated from it by some inter- 

 vening tissue, the existence of which, and the occurrence of a 

 definite cellular investment to the brown body, arer indications 

 that the embryophore is more advanced in its development 

 than was that of the former figures. 



The investment of the brown body has in fact become a 

 perfectly definite structure, sharply marked off from the sur- 

 rounding tissues. The part of it which lies distally to the 

 brown body has become thickened, and the nuclei are here 

 arranged in several layers, while they occur in a single layer 

 at the sides of the brown body. Distally to the thickened 

 part is a slit-like cavity, which will be termed the vestibule. 

 The morphology of these parts will be considered in the final 

 part of the paper. 



Fig. 16 is a still later stage (T. phalangea), as is shown 

 by the more advanced development of the embryophore and of 

 the embryo. The latter now consists of a considerable number 

 of cells, still lying in a follicle- cavity. The embryophore is 

 rather longer than before, and the investment of the brown 

 body is now thickened laterally and proximally, as well as 

 distally. A special growth of the investing tissue is taking 

 place proximally to form the "nutritive tissue,^' destined 

 hereafter to form the reticulum in which the secondary 

 embryos lie. As it appears probable that this reticulum is 

 directly or indirectly concerned in the nutrition of the rapidly 

 growing mass of embryos, the term here suggested may con- 

 veniently be used for descriptive purposes. The investment 

 of the brown body in fig. 16 shows some signs distally of 



