19G BEPORT ON THE PENNATL'LIUA. 



lar;t;e and evident geinninal vesicle containing one or more large spher- 

 ical genninal spots. 



Ova occur in all tlie leaves of the female specimen except the very 

 youngest ones, those at the bottom of the rachis, and as a rule in each 

 component polype of the leaf. They are far more abundant in all 

 stages of development at the lower or basal end of the polypes, where 

 they often form compact masses completely filling up the polype 

 cavities, than at the upper ends. 



The ripe eggs are found in small numbers near the upper part of 

 the polypes, and, as Johnston has pointed out, " by a little pressure 

 can be made to pass through the mouth." * Lacaze-Duthiers holds 

 that fertilization and the earliest stages of development are effected 

 within the body of the parent, the embryo escaping as a ciliated 

 plauula, which, after swimming freely for a time, fixes itself, grows 

 up and developes by repeated budding into a, Pennatiila; and Dalyell's 

 description of the process as observed by himself in Virriularia strongly 

 supports this view.f 



The male reproductive organs are very similar to the female ones. 

 They develope in exactl}' the same situation, and in a very similar 

 manner. When adult, they are alixiost identically the same size as the 

 ova, and have very much the same appearance, even under moderately 

 high powers of the microscope. So close is the resemblance, and so com- 

 pletely do the spermatospheres or spherical masses of spermatozoa 

 (Figs. 3, 4, 5, ts) counterfeit the ova of the female, that nothing could 

 be easier than to mistake the males for females. 



We ourselves fell into this error at first, and for some time were 

 under the impression that our male specimen was, from the apparently 

 obvious eggs that it contained in such large numbers, really a female ; 

 and it was only after cutting sections of these supposed eggs and 

 examining them with high powers [^^ in. and jj^iu.), that we discovered 

 their real nature. 



Like the eggs in the female, the male organs are developed on the 

 edges of the septa, which bear, higher up, the short, thick^ mesenterial 

 filaments. So far as we have been able to determine only four of these 

 six septa bear these organs, namely, the dorsal and ventral pairs of 

 each polype cavity, the pair belonging to the under surface of the leaf 

 being, as a rule, if not indeed constantly, sterile. 



As in the female the reproductive organs are borne by all the leaves 

 except the very youngest, and by all the polypes of each leaf, being far 

 more abundant in all stages of development at the basal ends of the 

 polypes than towards their free extremities. 



In the earliest stages of development that we have noticed, the 

 male organs (Figs. 4 and 5, ts) are small knobs composed of spherical 

 nucleated cells, surrounded by a capsule of flattened e]3ithelial cells, 

 and attached to the edge of the septum by a short stalk. 



In the next stage, the spermatosphere, as we may call it, has 



* Jolmstou : " British Zoophytes," vol. i., 2ud Ed., 1847, p. 159. 



i Dal yell ; '" Hare and Hemarkable Auiuials of Scotland," 1848, vol. ii., p. 188. 



