ON THE DEVELOPMENT Of TUBULIPORA. 143 



phore is seen to be considerably lobed in a more or less palmate 

 way. The proximal part is cylindrical, and occupies the cavity 

 which represents the fertile zocEcium before it became an ovi- 

 cell. This part, together with the greater part of the digitate 

 lobes, is practically solid; and consists, as in Crisia and 

 Lichenopora, of a reticulum of nutritive tissue, containing a 

 very large number of secondary embryos in all stages of devel- 

 opment. The distal ends of some of the lobes can be seen to 

 be hollow, although the thickness of the colony makes it im- 

 possible to make out all the details. The ooeciostome is at the 

 end of the lobe marked o., and this is hence the axial lobe. 

 The greatest length of the solid part of the embryophore, from 

 the proximal end to the distal tip of the most projecting lobe, 

 is 2'5 mm. 



Sections through ovicells in this stage are readily intel- 

 ligible by comparison with stage F. A comparatively young 

 ovicell, which had a transverse diameter of about 1"5 mm. 

 (measured in the sections), had a five-lobed embryophore. 

 The middle lobe was in connection with the vestibule, and the 

 two lobes of each side had resulted from the bifurcation of the 

 primary lateral lobes. The distal end of each of the five lobes 

 of the embryophore was hollow, while the proximal part was 

 filled up with a mass of young secondary embryos. Excretory 

 vesicles were numerous in the growing edge. 



The fertile brown body can still be discovered, lying freely 

 in the cavity of the embryophore, in some of the earlier ovicells 

 belonging to this stage. 



The mass of embryonic tissue increases very greatly, and in 

 the younger ovicells it is easy to see that embryonic fission is 

 or has recently been taking place. In the most satisfactory 

 series I possess illustrating this point, the ovicell contained 

 (in addition to numerous young secondary embryos) an embry- 

 onic mass, elongated in the direction of the axis of the ovicell, 

 and measuring about 160 fx in length. This mass was very 

 similar to the corresponding structure which I have described 

 at the beginning of embryonic fission in Crisia (15, pi. xxiii, 

 fig. 11). Karyokinetic figures were clearly seen in a large 



