122 University of California Publications. [zoology. 



Figs. 9 and 10, which represent serial sections from the growing 

 tip of a female colony, each of which shows the accumulations of 

 modified mesodermal cells in the angles of the branch (ger. els. ) . 

 They are found, too, at a time earlier than that at which the poly- 

 pide bud appears. This is especially clear in PL XII, Fig. 11, 

 representing a section of the bud-forming region of a female 

 colony. At the anterior edge of the tip are the germ cells (ger. 

 els.), while proximal to these is a series of polypide buds in 

 various stages of development. In the oldest bud (pd. bd. l) 

 the cavity of the stomach is visible (sf.). No ova have united 

 with any of these buds, and an examination of older portions of 

 the branch does not reveal their existence in the older zocecia. 

 On the other hand, numberless sections prove that not only are 

 single, detached ova produced at the anterior extremities of the 

 branch, but it is in these places that the ovaries are located. 

 Evidence of this is given in PI. XII. Fig. 12, and PI. XIII, 

 Figs. 13 and 14, consecutive sections taken somewhat obliquely 

 through the germinal region of the tip of a colony. The line 

 of cells (sep.) in the three sections, represents different parts 

 (if the same septum. Fig. 12, the first section of the series, 

 is composed mainly of cells forming the ventral w r all, the heap of 

 cells lying near the septum (pd. bd. 2) representing the outer 

 layer of a polypide bud. Fig. 13 represents the same polypide 

 bud (pd. bd.2), while proximal to it is another (pd. bd . l) . 

 Distal to the anterior bud (pd. bd . l>) in this section, live cells 

 of an ovary are shown, one of which (ov.) has advanced con- 

 siderably in development. Fig. 14 shows an ovum (ov.) from the 

 same ovary, which lies in close proximity to a polypide bud 

 (pd. bd. /). From this point forward there extends to the tip 

 of the branch, an almost unbroken line of ova, constituting an 

 ovary. A similar condition is represented in PI. XIII, Fig. 1.3, 

 a section from another colony, where several ova lie close to the 

 septum (sep.), within the cavity of the branch. These are in 

 close proximity to a mass of small cells (pd. bd. '.'), and consti- 

 tute the older portion of an ovary (orij.), which as succeeding 

 sections show, extends forward to the anterior edge of the branch. 

 Examination of a great number of series reveals the same con- 

 dition, i.e., the formation of groups of ova, or ovaries at the tips 



