170 MR, A. TV. WATERS ON 



and in this protoplasmic reticulum there are a number of large 

 isolated cells, suggestive of" ovarian cells ; but at first I could not 

 find proof of this, though ultimately some groups of these cells 

 were found so closely resembling the ovaria of yarious Bryozoa as 

 to leave no doubt that we have here ovaria formed in or on the 

 border of the protoplasmic reticulum. 



In the Chilostomatous Bryozoa the position of the ovaria 

 difiers according to the species, and the position may often turn 

 out to be a specific character of some importance : sometimes 

 it is at the side of tbe zooecium, sometimes, in fact frequently, 

 it is close to the base of the caecum, but in all cases attached to 

 the parenchym-tissue. The protoplasmic network spreads to all 

 j)arts of the zocecium, but is usually abundant at the base of tbe 

 caecum, so that some authors have spoken of a funiculus where 

 it does not exist. Figures are given, for comparison, of an 

 Alcyonidmm (PL 20. figs. 8, 9, 10) in which the ovarium occurs 

 close to the caecum, and grows within a separate protoplasmic 

 network, with large nucleated ova (see p. 180). 



It would thus seem as if, while the differences are very great, 

 there are some points of comparison between the formation of 

 the ovarium within the ovicell of S. liclienoides and within the 

 zooecium of some Chilostomata and Ctenostomata ; but there 

 are important questions which my sections do not answer: — Are 

 the ova fertilized by the spermatozoa within the ovicell? and in 

 w'hat way is there a connection between the originating zooecium 

 and the ovicell ? 



Until more sections have been made it must remain an open 

 question, whether this continuous growth of ovarian cells within 

 the protoplasmic network is supplementary to " embryonic 

 fission," or in what way it is related to it, for it does not seem to 

 me to entirely fall in with the description given by Harmer *. 



The calcareous wall of the ovicell is formed by tbin vertical 

 bars between the outer and inner surfaces, enclosing spaces ; but, 

 being rather fragile, it is difficult to make sections. The figures 

 given by Smitt of the dorsal surface of H. liclienoides are very 

 characteristic, but in dried or incinerated specimens the rows of 



* Harmer says: — "The primary embryo consists of a mass of embryonic 

 cells (or rather, nuclei imbedded in continuous protoplasm) which are obscurely 

 differentiated into outer and inner cells (or nuclei). The whole function of this 

 embryo is to act as an embryogenic organ, or producer of secondary embryos." 

 — Quart. Journ. Micr. Sci. n. s. vol. xxxiv. p. 209. 



