126 SIDNEY F. HARMBB. 



shows no sign of alteration; or it might be a centrosorae, a 

 view which hardly appears likely, frona the fact that it stains 

 readily with hjematoxylin. I have not discovered the nature 

 of this body. 



In stage B (fig. 13) I have seen what I believe to be sperma- 

 tozoa in the follicle cavity ; but I have not observed the ferti- 

 lisation of the egg. 



I have never found a testis in an ovigerous zocecium, contrary 

 to what may happen in Lichenopora. The testes appear in 

 the majority of zooecia, and usually in all those which produce 

 no eggs, in the same position as the ovaries of the female 

 polypides; the colony being thus monoecious. The young 

 testis is distinguishable from the young ovary owing to the 

 fact that it consists of a small group of nuclei at the proximal 

 apex of the caecum of the polypide. The testes grow con- 

 currently with the polypide to which they belong, and they 

 occur at all stages of the development of the ovicell. Owing 

 to the great size they reach, they form a very conspicuous 

 feature of sections, and can readily be seen in colonies mounted 

 whole. They fill up the proximal end of the zooecia with a 

 great mass of developing or mature spermatozoa, and they may 

 reach the length of 670 fx (T. plumosa). When the testis is 

 mature, the ripe spermatozoa may be seen extending up the 

 side of the polypide, and may even be massed between its 

 tentacle-sheath and body-wall. I have not ascertained the 

 mode of escape of the spermatozoa. 



The testes are thus produced in the great majority of the 

 zooecia, while ovaries are developed in but few, and an embryo 

 in an extremely restricted number. This seems to make it 

 probable that cross-fertilisation takes place, the great number 

 of spermatozoa that are produced being probably in some way 

 discharged into the surrounding water before fertilisation is 

 effected. 



The occurrence of large testes had no relation to the age of 

 the corresponding ovicell ; whilst in Lichenopora (16, p. 

 127) there was evidence of the disappearance of the testes 

 with increasing age of the ovicell. The apparent difference 



