no DISCOVERY REPORTS 



The figures given here (Plate XXXII) of zooids from the above-mentioned material support in an 

 indisputable way the view of the hermaphroditism of//, cylmdrica. As is shown in Plate XXXII, fig. i, 

 illustrating an individual from a colony collected by the Discovery Expedition, in January, the female 

 and the male reproductive organs are both present. They are situated on the right side of the body, 

 on the bend of the intestine. The testis is placed to the side of the ovary. A large brood-pouch is 

 developed on the dorsal side of the thorax. 



In the zooid figured the ovary consists of two large eggs. In some zooids two to three large eggs 

 have been observed at the same time. The oviduct is thin-walled, long and broad, running along the 

 ascending part of the intestine. The distal part is narrow. In the figure the oviduct is seen entering 

 into the brood-pouch with its distal narrow part. As mentioned above, the brood-pouch is well 

 developed. It is in the form of a large rounded sac. 



The testis is well distinguished, though not very much developed in the individual in question. It 

 consists of small rounded glands, which seem more or less emptied of their contents. The vas deferens 

 is represented by a wide duct of considerable length and with several windings. It is situated on the 

 external side of the oviduct and runs up along the intestine and the rectum. It opens at the side of the 

 anus, and its distal part is seen in the figure given. 



The individual illustrated in Plate XXXII, fig. 2, is from a colony dredged by the British Graham Land 

 Expedition at Stella Creek, in December. In this zooid the male reproductive organs are in a highly 

 developed stage. The testis consists of a great number of glands, of rounded or oval shape, forming 

 a large mass of mulberry-like aspect. The vas deferens is still a narrow tube, sinuous, but shorter, 

 being without the deep windings seen in the Discovery sample described above. It accompanies the 

 ascending branch of the intestine. 



Of the female reproductive organs, however, only rudimental traces are to be seen. Three small 

 follicles of whitish colour situated on the external side of the testis (cf. Plate XXXII, fig. 2) represent no 

 doubt the ovary. The oviduct could not be distinguished. A rudiment of the brood-pouch is distinctly 

 to be seen, though it is only little developed. 



The facts pointed out above prove that H. cylindrica is hermaphrodite. The colonies and the zooids 

 are not either male or female, as is the view of several previous authors. But whether the male and 

 the female reproductive organs attain their full development at the same time or at different seasons 

 is another problem. 



If we consider the states of maturity of the reproductive organs in the zooids figured and the 

 difference in season when the material was collected, certain conclusions may be justified. 



The zooid shown in Plate XXXII, fig. 2, is from a colony taken in December, the last month of the 

 year, i.e. early in the Antarctic summer. The zooid shown in fig. i is from a colony taken in 

 January, the first month of the year, i.e. in the full summer in the Antarctic region. 



In the first-mentioned individual the male reproductive organs are highly developed, and the testis 

 seems to have attained its full maturity. The vas deferens is a long sinuous tube. The female repro- 

 ductive organs are in a rudimentary stage. The ovary is represented by three small ova, and the 

 oviduct is not to be seen. The rudiment of the brood-pouch is in the form of a small vesicle. 



In the individual from the colony dredged in the Antarctic summer the female reproductive organs 

 are in their full development. The ovary consists of large ova, the oviduct is distinctly differentiated, 

 and the brood-pouch is represented by a large rounded vesicle attached to the body by means of 

 a narrow neck. The male reproductive organs seem to be in a reduced stage. The testis consists of 

 a small number of thin follicles lying at the side of the ovary, but the vas deferens is still a duct of great 

 length and width, winding up along the intestine and the rectum. 



From the state of maturity of the reproductive organs mentioned above it is apparent that the male 



