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true ovary and ova we are at once led to expect the co-exist- 

 ence of a male organ. That a testis is present in all the spe- 

 cies of fresh-water polyzoa there can, I think, now be little 

 doubt. In most of the genera I have met with an organ 

 which I have little hesitation in viewing as a testis, though, 

 with the exception of Paludicella, the demonstration of such 

 an organ is somewhat obscure. In this genus, however, I 

 have had the most satisfactory demonstration of both testicle 

 and ovary, the one loaded with spermatozoa, the other 

 with ova. 



" The ovary and testis in Paludicella articulata are both 

 found in the same cell. The former is an irregularly shaped 

 body adherent to the inner surface of the internal tunic, to- 

 wards the upper part of the cell. About the end of June, when 

 I discovered this organ, it was loaded with ova of various 

 sizes, some so small as to require for their detection a high 

 power of the microscope, while others were almost visible to 

 the naked eye, and seemed ready to burst the restraining 

 membrane of the ovary, and escape into the cavity of the cell. 

 Attached by one extremity to the external surface of the sto- 

 mach, near the commencement of the intestine, and by the 

 other apparently in connexion with the ovary, is a cylindrical 

 flexible cord which obeys all the motions of the stomach. Of 

 the nature of this appendage, which thus brings the ovary into 

 connexion with the stomach, I have been unable to arrive at 

 any satisfactory conclusion ; it can scarcely be an oviduct 

 communicating with the cavity of the stomach, and thus 

 affording through the latter organ a way of egress to the ova ; 

 for even though it be tubular, a condition not by any means 

 apparent, it is evidently too narrow to receive the mature ova, 

 even supposing it to undergo as much dilatation as would seem 

 possible with such an organ. 



" The testicle is an irregularly lobed mass, attached, like 

 the ovary, to the inner surface of the lining membrane of the 



c 2 



