6 SIDNEY F. HARMER. 



the condition of the branch when the growing-point was at the 

 level of that line. It follows from the shape of the ovicell, 

 that an ovicell which is half grown will have the form of a 

 wide-mouthed funnel, as shown in the figures of Smitt and 

 others. But although it is easy to recognise a young ovicell 

 at this stage, it is anything but an easy matter to distinguish 

 the ovicell while it is still a sub-median member of the 

 growing-point. 



The ovicell is indeed merely a modified zooecium, as is 

 shown by the method of its development, as well as by its 

 internal structure. Further evidence for this statement is 

 afforded by the occasional occurrence of abnormal units of the 

 colony, intermediate in form between the zooecia and ovicells 

 (17, pi. xii, fig. 12). 



In PI. Ill, fig. 19, the proximal portion of the ovicell is 

 already developed. The first, second, and third units of the 

 internode are zooecia, the fourth being an immature ovicell. 

 The growing-point is formed, on the right side, by the base of a 

 lateral branch, which would have been borne by the fifth 

 member of the internode. There follow, in order from right 

 to left, the fifth unit, the actual growing-point capable of pro- 

 ducing fresh zooecia, the sixth unit, and the ovicell. The last 

 occurs at the left side of the growing-point ; but while its 

 proximal end is in the same plane with the zooecia of the inter- 

 node, the open end of the funnel is already projecting forwards 

 (i. e. in the direction of that surfaceof the internode on which 

 the zooecia open). This condition becomes more prominent at 

 a later stage, so that the ovicell, in its most swollen portion, 

 projects considerably beyond the level of the general surface 

 of the internode. 



By referring to pi. xii, fig. 11, of my former paper (17) it will 

 be seen that the zooecium "5" (in fig. 19) would have formed 

 its aperture at the level of the middle of the ovicell, while "6" 

 would have completed its growth at a very short distance 

 above it. 



The young ovicell has, at first sight, the appearance of an 

 open funnel. This is not really its condition, since its end is 



