XLII 



NOTE ON THE REPRODUCTIVE ORGANS OF THE 

 CHEILOSTOME POLYZOA. 



Quart. Journ. Microsc. Sci., vol. iv-, 1856,//. 191-192. 



Obvious as are the ovicells and partially-developed ova of the 

 cheilostome Polysoa, the precise position of their ovaria and testis has 

 not yet been determined ; the general idea that the ova are developed 

 within the ovicells being wholly an assumption. The investigation 

 of the question is not without difficulty, on account of the delicacy of 

 the ova in their young condition, the greater or less opacity of the 

 ectocyst, and the obstruction offered by the other viscera if the cells 

 be viewed in any of the positions which they ordinarily assume, lying, 

 that is, on their front or back faces. By tearing up a polyzoarium, 

 with needles, into single series of cells, and causing one of these series 

 to lie upon its side, I found the process of examination much 

 facilitated. 



In the younger cells oi Bitgula avicularis, I find that, as in many 

 of the hippocrepian Polyzoa, there is a cord, or funiculus, connecting 

 the extremity of the stomach with the bottom of the cell, and attached 

 to this I found, close to the stomach, a single small pale ovum, 

 commonly possessing a double germinal spot. At its lower attach- 

 ment, on the other hand, the funiculus is surrounded by a mass of 

 minute, pale, spherical corpuscles. In these cells, no ovicells were as 

 yet developed ; but in older cells they make their appearance as 

 diverticula of the ectocyst and endocyst, having their internal cavity 

 continuous by a narrow neck with that of the cell. A valvular 

 aperture eventually becomes developed at the lower part of their 

 anterior face. 



In such older cells, the ovicell is at first empty, and we find the 

 ovum attached to the funiculus increasing in size, and acquiring a 



