Physiology of some Zoophytes. 399 



the cilia were acting very languidly. I saw another while swim- 

 ming about become entangled by its cilia to the setse projecting 

 from the body of a small annelidc. During the movements of 

 the annelide, the hairs on the prolonged anterior extremity came 

 in contact with some small fragments of sea-weed, and the an- 

 nelide after some struggles detached itself from the ovum, which 

 continued to adhere to the sea-weed. In all of these I never 

 observed the least movement of the hairs attached to the anterior 

 extremity. I was not able to ascertain that the smaller portion 

 of the ovum left in the capsule underwent any change, as I pre- 

 sume it does, before it escaped from its interior. Several bodies, 

 having one portion of their surface ragged and devoid of cilia, 

 and in every other respect resembling the smaller portion of the 

 ovum, and also other bodies exactly similar to the entire ovum, 

 were observed swimming about; but as ii, all these cases the 

 portions of the polypidom had been injured immediately before, 

 and some of the ovary-capsules broken, it was presumed that 

 these had been mechanically displaced from the capsules. The 

 larger portions of the ova were, like the entire ova, composed of 

 minute nucleated cells, and did not, as far as I could discover, 

 possess any internal cavity. 



In several specimens of Cellularia reptans and C. scruposaj and 

 one specimen of C. avicularis procured at the same time, the 

 ovary-capsules were filled with ova ; in the two former of a deep 

 orange colour, composed of nucleated cells, having the same 

 number and arrangement of membranes and provided with cilia 

 as in Flustra avicularis. Some of these ova were in rapid rota- 

 tory motion ; others, as in Flustra avicularis, were motionless, 

 though the cilia were acting, being kept quiescent by the more 

 close apposition of the inclosing membrane. I did not succeed 

 in observing the escape of any of these ova from their capsules. 

 In many of the polype-cells of all of the above-mentioned 

 polypes, dark red bodies composed of nucleated cells inclosed in 

 a membrane were present. These nucleated cells are generally 

 considerably larger than those entering into the formation of 

 the ova in the ovary-capsules. The greater number of polype- 

 cells contained one only of these bodies, and it was connected 

 to the inner surface of the cell by a membrane having a num- 

 ber of detached nucleated cells of a light colour adhering to it. 

 These bodies occupied dificrent positions between the bottom 

 and aperture of the cells, but in none were distinct ciliary mo- 

 tions observed. These bodies are also probably ova, and it is 

 possible that more extended observations may enable us to de- 

 tect cilia on their surface at a more advanced stage of develop- 

 ment, though none in the present case were seen even on those 

 lying at the aperture of the polype-cells. I have satisfied my- 



