ON THE DEVELOPMENT OF TUBULIPORA. 155 



Fig. 10. — T. plumosa. Ovarian egg, in follicle (stage A). 



Fig. 11. — T. plumosa. Stage B, the embryo consisting of two blasto- 

 raeres. The caecum of the fertile polypide (whicii has not yet degenerated) is 

 seen ; /, and the corresponding structure to the left are probably the degene- 

 rating follicles of eggs which are not developing. 



Fig. 12. — T. phalange a. Degeneration of the fertile polypide (stage B). 

 The tentacles, which are better seen in neighbouring sections, have lost their 

 distinct outlines, and are obviously degenerating. AB = 300 fi. 



Fig. 13. — T. phalangea, stage B. Three blastomeres are seen in the 

 follicle-cavity, wiiich also contains a spermatozoon. The brown body still 

 shows traces of the alimentary canal of the fertile polypide. 



Fig. 14.— T. phalangea. Early stage D. A B = 165 /i ; C B = 75 //. 



Fig. 15.— T. plumosa. Early stage U. AB = 200 /*. 



Fig. 16. — T. phalangea. Late stage D, as shown by the considerable 

 development of the cellular investment of the brown body, and particularly by 

 the development of the nutritive tissue on the proximal side. The terminal 

 membrane is deeply invagiuated, and the vestibule is visible. A B = 250 /x ■ 

 CB = 110/i. 



Fig. 17. — T. phalangea. Late stage D; obliquely longitudinal section 

 of the distal end of the ovicell, to show the oblique, constricted junction of the 

 vestibule with the embryophore. The invagination of the terminal membrane 

 is not cut so as to show its opening to the exterior. 



Fig. 18. — T. plumosa. Rather early stage D, with very numerous excre- 

 tory vesicles. The vestibule is small. The cellular investment of the brown 

 body is thickened distally (X). There is at present no nutritive tissue. 

 A B = 225 /u, C B = 85 ju. 



Fig. 19. — T. plumosa. Early stage E. The nutritive tissue is largely 

 developed, and the embryophore is becoming vacuolated. The embryo has 

 increased in size. The section passes on one side of the median invagination 

 of the terminal membrane. A B = 460 /x, C B = 165 fi. 



Fig. 20. — T. liliacea. Early stage E. The embryophore is longer than 

 in the other species, y. Plug of cells between vestibule and embryophore 

 (see p. 148). A B = 630 //, C B = 255 /i. 



Fig. 21. — T. liliacea. Younger ovicell (late stage D). The embryophore 

 is much elongated, as in Fig. 20. 



Fig. 22.— T. plumosa. Ovicell at middle of stage E. y, corresponding 

 with the similarly lettered part in figs. 20 and 25, has now acquired a lumen. 

 A B = 960 /i, C B = 355 ix. 



