54 



to the fuiH'lion of the ocecia. He has seen the formation of the egg in the 

 zocecinm and while the ooecium originally was empty he found it at a certain 

 lime containing an egg, without heing able to ascertain how it came there. He 

 expresses the following supposition: »wahrscheinlich zwangt sich das Ei durch 

 den hohlen Stiel der Ovicelle und tritt durch eine OefFnung, welche ich an der 

 Stelle, wo die beiden Blasen zusanimenhangen, gelegcn vernuillie, in den Raum 

 zwischen den beiden Blasen." Nitsche tries to explain Hincks' different view, 

 that the eggs are formed by a granular mass in the ooecium in the following way, 

 that the egg after its transference to the ooecium instead of developing further, 

 sometimes dies away and dissolves into a shapeless mass. Finally, he states that 

 the supposed eggs, wliich Hincks has observed in zocccia without polypide, are 

 only peculiar bodies which liave arisen from a retrogressive metamorphosis of 

 the polypide. 



In ^Contributions to the liistory of the Polyzoa«, where Hincks* introduces 

 the new name »o(rcium«, he admits the correctness of Nitsche's assertion, fliat 

 the supposed eggs, which he had discussed earlier, are really the so-called » brown 

 bodies<s and he assents to Huxley's view of the ociccia as marsupial chambers. 

 He adheres liowever to the idea, that eggs can now and then be formed in I he 

 ocecia and maintains the correctness of the observations which he fornierly made 

 on this subject in a few Biigiila species and Bicellaria ciliata. In his later published, 

 principal work- he definitely expresses the view that the ooecium has an internal 

 connection with the zoax'ial cavity ('>its interior is in direct communication with 

 the perigastric cavity«), but otherwise there is no further information on the 

 structure of the ooecia. They are indicated as prominent*, "sul)immerse(l < and 

 »immersed< {Fliistra, Cellaria), according as they are more or less prominent on 

 the surface of the colonj' or hidden within this. 



Vigelius-' in his investigations on Fliistra inembrnnaceo-lnincala has given a 

 description of the structure and develo]Hncnt of the on>cia in this species. While 

 the oa'cium and its operculum in BicclUirid ciluita arise as two outpushings from 

 the frontal wall of the zooecium, the ooecium in this species arises as an inva- 

 gination from this wall, a short way dislally to the operculum and it thus conies 

 to protrude into the zoa'cium as a hollow bladder, the interior part of which 

 enters into connection with the distal wall of the zooecium, which is here formed 

 in a peculiar way. It consists namely of a horizontal, under part, which oi'igi- 

 nally reaches right to the frontal wail of the zoa'cium and of a distally and 

 slightly basally inclined part, which grows together with the ooecial bladder. 



» 38; « 22; ' 105, p. 



