188 SIDNEY F. HARMER. 



than before; the brown body has diminished in size, but the 

 embryo is not greatly changed. The most noticeable difference 

 between this and the earlier stage is in the embryophore, the 

 proximal part of which is much more developed than before. 

 The nutritive tissue is, in fact, now much increased in amount, 

 and the embryo is thereby further removed from the brown 

 body. 



The nutritive tissue is becoming vacuolated in fig. 19, and 

 further spaces are originating between it and the outermost 

 wall of the embryophore. This leads to the condition of 

 fig. 23, a considerably older stage (of the same species) drawn 

 to the same scale. 



Fig. 22 is from a distinctly bilobed colony, each lobe of 

 which contains an ovioell in stage E. The two ovicells con- 

 verge proximally, as can be seen from the sections, which are 

 parallel to the basal lamina of the colony. Their proximal 

 ends extend far down into the part of the colony which is 

 common to the two lobes, so that it is clear that the colony 

 was in an unlobed state when the development of the ovicells 

 commenced. 



The most important difference between fig. 22 and fig. 19 is 

 that the part of the embryophore containing the nutritive 

 tissue consists in the former of a long, cylindrical, thin-walled 

 portion, containing a loose inner mass of cells which do not 

 nearly fill its cavity. There is still no great increase in the 

 development of the embryo. 



Fig. 20 is a section of an ovicell of T. liliacea in the same 

 stage, and it confirms the conclusion drawn from fig. 21 that 

 T. liliacea is characterised by the great length of its embryo- 

 phore. The ovicell here figured is about as much developed as 

 fig. 19 (T. plum OS a). The distance of the brown body from 

 the embryo is very different in the two cases. 



The condition of the ovicell towards the end of this stage is 

 illustrated by fig. 25, representing an ovicell, probably of T. 

 phalangea, cut horizontally, as is shown by its considerable 

 breadth. The embryo has now enlarged to a marked extent, 

 and measures 80 fx in its greatest length, which is about three 



