44 EEPORT ON THE PENNATULIDA. 



membranous sheath, aud later ou by a second outer, very thick and 

 strong capsule, formed by the surrounding epithelial cells. During the 

 greater part of their development the ova are attached by short stalks 

 to the edges of the septa, and project freely into the body-cavity of the 

 polype. 



When ripe the ova become detached from the stalks and lie freely 

 in the polype-cavity. Each ripe ovum is a spherical body about 0-015 

 in. diameter, consisting of a very dense pigmented outer capsule of 

 great strength and considerable thickness, with its surface marked as 

 in Funiculiiia by an irregular network of low ridges, and i^resentiug at 

 one spot a very conspicuous aperture or micropijle for admission of the 

 spermatozoa ; within this capsule is a second inner and much thinner 

 membrane, inside which is the ovum itself ; this consists of granular 

 protoplasm imbedded in which, iisually close to one side, is a very 

 large and evident germinal vesicle containing one or niore lai'ge spher- 

 ical gemiinal spots. 



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

 youngest ones, those at the bottom of the rachis, aud 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 completeh' filling up the polype- 

 cavities, than at the upjDer ends. 



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

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

 can be made to pass through the mouth."* Lacaze-Duthiei's holds 

 that fertilisation and the earliest stages of development are effected 

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

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

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

 description of the process as observed by himself in Virrjularia strongly 

 supports this view.f 



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

 They develope in exactly the same situation, and in a very similar 

 manner. When adult they are almost 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 



* Johnston : " British Zoophytes," vol. i., 2nd Ed., 1847, p. 159. 



1 Dalyell "Karc and Remarkable .\uiuials of Scotland," 184ti vol. ii. p. 188. 



